Activation of hemostasis after off-pump coronary artery...

Activation of hemostasis

after off-pump coronary artery

bypass graft surgery

Bernard Lo

ISBN-10: 90-9021414-3

ISBN-13: 978-90-9021414-6

Printedby: GildeprintB.V.,Enschede

Cover&layout: Multimedia(EstherBeekman),UMCUtrecht

Activationofhemostasisafteroff-pumpcoronary

arterybypassgraftsurgery

Stollingsactivatienacoronairebypasschirurgiezonderhart-longmachine

(meteensamenvattinginhetNederlands)

Proefschriftterverkrijgingvandegraadvandoctor

aandeUniversiteitUtrecht

opgezagvanderectormagnificus,prof.dr.W.H.Gispen,

ingevolgehetbesluitvanhetcollegevoorpromoties

inhetopenbaarteverdedigenop

donderdag18januari2007desmiddagste2.30uur

door

Bernard Lo

geborenop21februari1974teEindhoven

Promotor

Prof.dr.C.J.Kalkman

Co-promotores

Dr.R.Fijnheer

Dr.A.P.Nierich

Beoordelingscommissie

Prof.dr.Ph.G.deGroot

Prof.dr.J.W.N.Akkerman

Prof.dr.L.vanHerwerden

Prof.dr.L.P.H.J.Aarts

Prof.dr.G.J.Scheffer

TheoriginalOctopus-trialwasfundedbygrantOG98-026fromtheNetherlandsNational

HealthInsuranceCouncil.Additionalfundingforlaboratoryresearchforthisthesiswas

providedbyMedtronicInc.,Minneapolis,USA

Financialsupportforthepublicationofthisthesisisgratefullyacknowledgedandwas

providedby:

DivisionofPerioperativeCareandEmergencyMedicine,UniversityMedicalCenter,Utrecht;

AstellasPharmaB.V.;BayerB.V.;SinarJayaGroup,MedtronicB.V.,LEOPharmaB.V.;

ZLBBehringB.V.;AbbottB.V.;EdwardsB.V.;TycoHealthcareB.V.

Aan mijn ouders

Voor Herny, Patrick & Arlene

Chapter 1 Generalintroduction 10

Chapter 2 Pathophysiologyofthecoagulationsystemincardiacsurgerywith

andwithouttheuseofcardiopulmonarybypass 16

Chapter 3 Activationofhemostasisaftercoronaryarterybypassgraftingwith

orwithoutcardiopulmonarybypass

AnesthAnalg.2004Sep;99(3):634-40 34

Chapter 4 Activationofhemostasisisassociatedwithearlycognitive

declineafteroff-pumpcoronaryarterybypasssurgery

JThrombHaemost.2005Sep;3(9):2114-7 50

Chapter 5 RelativelyincreasedvonWillebrandFactorafteroff-pumpcoronary

arterybypassgraftsurgery

AcceptedbyThrombHaemost.2007 60

Chapter 6 Localanestheticactionsonthromboxane-inducedplateletaggregation

AnesthAnalg.2001Nov;93(5):1240-5 78

Chapter 7 C-reactiveproteinisariskindicatorforatrialfibrillationafter

myocardialrevascularization

AnnThoracSurg.2005May;79(5):1530-5 94

Chapter 8 Generaldiscussion 110

Summary 126

Nederlandsesamenvatting(summaryindutch) 132

Listofabbreviations 137

Dankwoord 138

CurriculumVitae 143

Publications 144

Contents

Chapter one

General introduction 1

IntroduCtIon

Coronary artery bypass graft (CABG) surgery on a beating heart was introduced with suture

techniquesandlocalstabilizationbyKolessovin1967.1However,theoutcomesofthistypeof

surgeryweregenerallyunpredictable,preventinggeneralacceptanceandwidespreaduse.The

useofcardiopulmonarybypass(CPB)andcardioplegicarrest(on-pumpCABG),withitsabilityto

provideaquietbloodlessfieldfortheconstructionofpreciseanddelicatesurgicalanastomoses,

offeredcompellingadvantagescomparedwiththeoff-pumpapproachandrapidlybecamemore

widely accepted.2 In the following decades, there was a tremendous increase in the number

of on-pump bypass procedures, reaching the clinical status of “gold standard” for coronary

revascularization.

Nevertheless, despite extensive research in this area, on-pump (or so-called conventional)

CABG,remainedassociatedwithsignificantmorbidity.3-7NegativesequelaeoftheuseofCPB,

includingactivationofahemostaticandinflammatoryresponse,nonpulsatileflowandpossible

embolization of air or debris could contribute to CPB-related organ dysfunction.3,8,9 This has

ledtoarenewedinterestinbypasssurgeryonthebeatingheart.Theinventionofcardiacwall

stabilizers such as the Octopus Stabilizer made it possible to immobilize and present all the

sidesofthebeatingheart,thusfacilitatingbypasssurgerywithouttheuseofCPB(off-pump

CABG).10

Duringthepastdecade,severalrandomizedcontrolledtrialshavedemonstratedbenefitsofoff-

pumpCABG,includinglowermorbidityrates,reducedlengthofhospitalstay,andlowercosts.11-

14Whetherthisreductioninmorbidityistheresultoflesspronouncedactivationofhemostatic

andinflammatorymechanismsinoff-pumpCABGneedstobedetermined.

The Octopus Study is a multi-center trial comparing cognitive outcome between patients

randomizedtooff-pumporon-pumpCABG.11,12,15Bloodsamplesoftheparticipantsofthistrial

wereusedforthisthesis.

The major goal of this study was to quantify activation of hemostasis and C-reactive protein

(CRP),asamarkerofinflammationinpatientsundergoingCABGwithorwithoutCPBandtheir

relationtoclinicaloutcome.

Chapter2givesashortoverviewofnormalhemostasisandpathophysiologicaleffectsofCPB

onthecoagulationsystem.Inaddition,strategiestoattenuatehemostaticactivationduring

CPBandactivationofhemostasisinoff-pumpcardiacsurgeryarealsodiscussed.Inchapter3of

thisthesis,postoperativeactivationofhemostasisafterthetwotypesofsurgeryiscompared.

Clinical significance of a hypercoagulable state after off-pump surgery is assessed in chapter

4, where associations with postoperative cognitive decline are presented. Activity of von

Willebrand Factor is compared directly after both types of surgery to determine the effects

of CPB and the surgical trauma in chapter 5. High shear forces in the CPB system may play a

chapterone12

role inenhancedvonWillebrandFactorproteolysis,making thismultimericglycoprotein less

effectiveinmaintainingprimaryhemostasis.16Amajorityofthepatientsundergoingoff-pump

surgeryreceivedthoracicepiduralanalgesia.Activationofhemostasismaybeaffectedbythis

assomelocalanesthetics,inconcentrationspresentinbloodduringepiduralinfusion,inhibit

thrombusformationinthepostoperativeperiod.Chapter6outlinesthepossibleeffectsoflocal

anestheticsonthromboxane-inducedplateletaggregation.Inon-pumpCABGpatients,ithas

been demonstrated before that postoperative CRP levels are associated with postoperative

arrhythmiasandthesearerelatedtobaselineCRPlevels.17Inthepresentthesis,associations

betweenbaselineCRPlevelsandstoperativeatrialfibrillationafterbothon-andoff-pumpCABG

arestudiedandpresentedinchapter7.

Finally,chapter8discussesthe implicationsofourfindings inawidercontext, togetherwith

suggestionsforfutureresearch.

13Generalintroduction

chapter114 References

references

1.KolessovVI.Mammaryartery-coronaryarteryanastomosisasmethodoftreatmentforanginapectoris.J

ThoracCardiovascSurg1967;54(4):535-544.

2. Favaloro RG, Effler DB, Groves LK, Sheldon WC, Sones FM, Jr. Direct myocardial revascularization by

saphenousveingraft.Presentoperativetechniqueandindications.AnnThoracSurg1970;10(2):97-111.

3. Butler J, Rocker GM, Westaby S. Inflammatory response to cardiopulmonary bypass. Ann Thorac Surg

1993;55(2):552-559.

4.TumanKJ,McCarthyRJ,NajafiH,IvankovichAD.Differentialeffectsofadvancedageonneurologicand

cardiacrisksofcoronaryarteryoperations.JThoracCardiovascSurg1992;104(6):1510-1517.

5. Roach GW, Kanchuger M, Mangano CM, Newman M, Nussmeier N, Wolman R et al. Adverse cerebral

outcomesaftercoronarybypasssurgery.MulticenterStudyofPerioperativeIschemiaResearchGroupand

theIschemiaResearchandEducationFoundationInvestigators.NEnglJMed1996;335(25):1857-1863.

6. Ascione R, Lloyd CT, Underwood MJ, Gomes WJ, Angelini GD. On-pump versus off-pump coronary

revascularization:evaluationofrenalfunction.AnnThoracSurg1999;68(2):493-498.

7.NewmanMF,KirchnerJL,Phillips-ButeB,GaverV,GrocottH,JonesRHetal.Longitudinalassessmentof

neurocognitivefunctionaftercoronary-arterybypasssurgery.NEnglJMed2001;344(6):395-402.

8. Dixon B, Santamaria J, Campbell D. Coagulation activation and organ dysfunction following cardiac

surgery.Chest2005;128(1):229-236.

9. Abu-Omar Y, Balacumaraswami L, Pigott DW, Matthews PM, Taggart DP. Solid and gaseous cerebral

microembolizationduringoff-pump,on-pump,andopencardiacsurgeryprocedures.JThoracCardiovasc

Surg2004;127(6):1759-1765.

10.BorstC,JansenEW,TullekenCA,GrundemanPF,MansveltBeckHJ,vanDongenJWetal.Coronaryartery

bypassgraftingwithoutcardiopulmonarybypassandwithoutinterruptionofnativecoronaryflowusinga

novelanastomosissiterestrainingdevice(“Octopus”).JAmCollCardiol1996;27(6):1356-1364.

11.vanDijkD,NierichAP,JansenEW,NathoeHM,SuykerWJ,DiephuisJCetal.Earlyoutcomeafteroff-pump

versuson-pumpcoronarybypasssurgery:resultsfromarandomizedstudy.Circulation2001;104(15):1761-

1766.

12.NathoeHM,vanDijkD,JansenEW,SuykerWJ,DiephuisJC,vanBovenWJetal.Acomparisonofon-pump

andoff-pumpcoronarybypasssurgeryinlow-riskpatients.NEnglJMed2003;348(5):394-402.

13.AngeliniGD,TaylorFC,ReevesBC,AscioneR.Earlyandmidtermoutcomeafteroff-pumpandon-pump

surgeryinBeatingHeartAgainstCardioplegicArrestStudies(BHACAS1and2):apooledanalysisoftwo

References 15

randomisedcontrolledtrials.Lancet2002;359(9313):1194-1199.

14.RajaSG.Pumpornopumpforcoronaryarterybypass:currentbestavailableevidence.TexHeartInstJ

2005;32(4):489-501.

15.vanDijkD,JansenEW,HijmanR,NierichAP,DiephuisJC,MoonsKGetal.Cognitiveoutcomeafteroff-

pumpandon-pumpcoronaryarterybypassgraftsurgery:arandomizedtrial.JAMA2002;287(11):1405-

1412.

16.VincentelliA,SusenS,LeTourneauT,SixI,FabreO,JuthierFetal.AcquiredvonWillebrandsyndromein

aorticstenosis.NEnglJMed2003;349(4):343-349.

17.BruinsP,teVH,YazdanbakhshAP,JansenPG,vanHardeveltFW,deBeaumontEMetal.Activationofthe

complementsystemduringandaftercardiopulmonarybypasssurgery:postsurgeryactivationinvolvesC-

reactiveproteinandisassociatedwithpostoperativearrhythmia.Circulation1997;96(10):3542-3548.

Chapter two

Pathophysiology of the coagulation system in cardiac surgery with and without the use of cardiopulmonary bypass

2

chaptertwo18

IntroduCtIon

Normalhemostasis

Hemostasis,thearrestofbleedingatthesiteofvascularinjury,isoneofthemostimportant

host defense mechanisms. It preserves the integrity of the closed, high-pressure circulatory

systembylimitingbloodlossaftertissuetrauma.Undernormalcircumstancesthere isafine

balancebetweentheendogenousanticoagulantsandprocoagulants.Endogenousanticoagulant

activity slightly overcomes the procoagulant activity which is necessary for the continuous

intravascular flow. The smooth surface of the endothelium contributes to the endogenous

activationofthecoagulationsystem.Whenthissurfaceisdamaged,occlusionoftheaffected

vesselwillfollow.Anyinjurytothevesselwallssuchasthoseduringsurgeryleadstoplatelet

plug formation (platelet adhesion and aggregation) and fibrin formation (by activating the

coagulationcascade).

D

Secretion of multimersfrom Weibel-Palade body

VWF multimers(VWF Ag)

ADAMTS-13

Blood flow

Endothelium

Subendothelium

VWF-propeptide

VWF A2

C

A

E

B

Platelet GP1b

VWF activityRistocetin cofactor assayCollagen binding assay

Figure 1.VonWillebrandFactor(VWF)isreleasedfromendothelialcellsasunusuallylargemultimerstogetherwith

itspropeptide.Thesemultimersdif fuseintothecirculation(AorB)oradheretoendothelialcellsurface(C).VWF

also binds to connective tissue exposed at sites of vascular injury. Under conditions of high fluid shear stress,

plateletcanadheretoVWFinsolution(B)oronsurfaces(CandD)throughtheglycoprotein1b(GP1b)receptor.VWF

mayalsorecruitplateletstopreviouslyadheringplatelets(E).ADAMTS-13cleavesVWFintheA2domain,areaction

whichisslowinsolution(A)butoccursrapidlyunderhighfluidshearstressconditionsoronsurfaces(C-E),presum-

ablyasaconsequenceofconformationalchangesinducedbythetensileforceontheVWFmultimer.ActivityofVWF

canbedeterminedbyboththeristocetincofactorassayandthecollagenbindingassay.

Pathophysiologyofthecoagulationsystemincardiacsurgerywithandwithouttheuseofcardiopulmonarybypass 19

First, circulating platelets adhere to the subendothelium that is exposed when the vascular

endothelialliningisbroken.Adhesionofplateletstotheendothelialbedismediatedthrough

the surface proteins that are produced and stored in platelets and endothelial cells such as

vonWillebrandFactor(VWF).Collagenandthefirstthrombinformedattheinjurysiteactivate

platelets.Thisleadstoaseriesofoverlappingeventssuchasplateletshapechanges,assembly

oftheglycoproteinIIb/IIIa(GPIIb/IIIA)receptor,andreleaseofsecondaryaggregatorsasADP

andthromboxaneA2.Hereby,theadhesionofplateletstoeachotherisenhancedandresultsin

furtherconsolidationofthepreliminarylooseplug.

VWFplaysan important role inprimaryhemostasisas it is involved in the initialadhesionof

blood platelets at sites of vascular injury. This multimeric plasma glycoprotein can bind to

bothexposedcollagenandtheglycoproteinIbreceptoronplatelets,herebyallowingplatelet

tetheringatthesiteofinjury.Thisisessentialtoinitiatethrombusformationonvascularsurfaces

exposedtorapidlyflowingblood.1VWFissynthesizedbymegakaryocytesandendothelialcells,

andreleasedintheformofagigantic,multimericproteinof20,000-kDainsize.Theproteolysis

ofthematuremoleculebyADAMTS-13,aplasmametalloprotease,down-regulatesthesizeof

plasmaVWFtoaseriesofmultimersrangingfrom450toover10,000kDa(figure1).2Thissteady

statedistributionofmultimersreflectsanequilibriumbetweenthesecretionoflargemultimers

andtheirproteolysisintosmallerinactivederivatives.BothVWFanditspropeptidearestored

in Weibel-Palade bodies in equimolar concentrations. When released in the bloodstream,

plasmaconcentrationsof theseproteinscanbeusedasamarkerofendothelialcelldamage.

AstheturnoverofVWF-propeptideismuchfasterthanthatofVWF,differentiationcanbemade

betweenacuteandmorechronicendothelialcelldamage.ActivityofVWF(whichincreaseswith

itsmolecularweight)canbedeterminedbyboththeristocetincofactorassayasthecollagen

bindingassay.

At thesametimeofplateletplug formation, thecoagulationsystem isactivated. It consists

of multiple serine protease proenzymes that become enzymatically active in a proteolytic

cleavage by another enzyme (figure 2). The cascade of enzymatic activation initiates via the

so-called extrinsic pathway. As a result of exogenous injury to the vascular endothelium,

tissuefactor(TF)isreleasedfromtheendothelialcells.TFbindscirculatingfactorVIIa(about

1% of circulating factor VII) and the VIIa/TFcomplex consequently activates itsphysiologic

substratesfactorIXandX.ActivatedX(Xa)activatesfactorVII,whichresultsinenhancementof

extrinsicpathwayactivation.TheroleoffactorIXa(togetherwithcofactorVIIIa)istoactivate

factorX,andthiscanalsobeinitiatedwhenbloodcomesincontactwithanegativelycharged

surface.Intheformerreaction,factorXII,highmolecularweightkininogen,prekallikreinanda

negativelychargedsurfaceactivatefactorXI,whichconsequentlyactivatesfactorIX(figure2).

However,thisso-calledintrinsicorcontactpathwayisnotveryrelevantinvivo.Regardlessof

thesource,thefinalstepsofcoagulationarecompletedbyactivationofthecommonpathway.

Activationofcoagulationleadstothrombinformation,whichcanbequantifiedbymeasuring

chaptertwo20

INITIATION OF COAGULATION

FIBRINOLYTIC SYSTEM

(Contact or intrinsic pathway)via HMWK,kallikrein, XIIa and XIa

(Extrinsic pathway)

TFPI

Tissue Factor

Tissue FactorVII

Xa

X

IXa Protein C

Protein S

IIaThrombomodulin

IX

Xa XIa

VIIa

VIIIa VIII

APC

IIa

XIII XIIIa

Fibrin Polymer

Soluble Fibrin

u-PAt-PA

XL-Fibrin

D-dimer

plasmin

plasminogen

α-2 Antiplasmin

IIa

IIa

Fibrinogen

Antithrombin

TAFI

PAI-1

F1.2

Va

II

V

Figure 2. Coagulationcascade

Coagulationisinitiatedbytheextrinsicpathwayviathetissuefactor-factorVIIacomplex,thatleadstoformation

offactorXa.TogetherwithactivatedfactorVaascofactor,factorXaleadstotheformationofthrombin(IIa).Throm-

binactivatesfactorXIandactivatedfactorXIatriggerstheintrinsicpathway.Thiscanalsobeinitiatedbycontact

activationortheintrinsicpathwayoffactorXII,althoughthisisclinicallynotveryrelevant.Theintrinsicpathway

sustainscoagulationviatheformationoffactorXathatleadstoamplif icationofthrombinformation.Thrombinalso

activatesfactorsVandVIII,whichresultsinapositivefeedbackinthecoagulationcascade.Inaddition,thrombin

activates protein C, TAFI, platelets, factor XIII and endothelial cells. Activated protein C inhibits factors Va and

VIIIa, providinganegativefeedbackofthecoagulationcascadeandTAFIpreventsprematuredegradationofthe

f ibrinclot.

IIa,thrombin;APC,activatedproteinC;HMWK,highmolecularweightkininogen;PAI-1,plasminactivatorinhibitor-

1;PL,phospholipidlayer;TAFI,thrombin-activatablef ibrinolysisinhibitor;TFPI,tissuefactorpathwayinhibitor;

t-PA,tissue-typeplasminogenactivator;u-PA,urinary-typeplasminogenactivator;XL,cross-linked;

Arrowsindicateactivation,dottedarrowsindicateinhibition


prothrombin fragment F1.2 (F1.2, a proteolytic fragment of prothrombin) or thrombin-

antithrombin complexes. Thrombin is a strong platelet activator and cleaves fibrinogen into

solublefibrinmonomers.Thesemonomerspolymerizetoaninsolublefibrinnetwork.Interaction

offibrin(ogen)withtheGPIIb/IIIAreceptoronplateletsstabilizesthehemostaticplug,sealing

theinjuredvessel.

Thefibrinolyticsystemisactivatedbyfibrindeposition.Bydissolvingfibrin,thissystemhelps

keep open the lumen of an injured blood vessel. A balance between fibrin deposition and

lysismaintainsandremoldsthehemostaticsealduringrepairofaninjuredvesselwall.Plasmin

is a powerful proteolytic enzyme that catalyzes fibrinolysis and is activated by tissue-type

plasminogenactivator(t-PA)orurinary-typeplasminogenactivator(u-PA).Itcleavesfibrinogen

andfibrinmonomerintofibrinsplitproductsandcross-linkedfibrinintoD-dimers.Thesesoluble

fibrin degradation products are swept into the circulation. In addition, plasmin inactivates

coagulationfactorsVaandVIIIa,andhasdirecteffectsonplateletmembranereceptorssuchas

GlycoproteinIb(whichbindsVWF)andGPIIb/IIIa.Toprotectthefibrinclotagainstdegradation,

thrombin at high concentrations can activate factor XIII and thrombin-activatable fibrinolysis

inhibitor(TAFI).FactorXIIIstabilizesfibrinbytheformationofcross-linksbetweenthevarious

fibrin chains. TAFI interferes with the binding of plasminogen to fibrin resulting in inhibition

of plasminogen activation. Other inhibitors of the fibrinolytic system are α-2 antiplasmin and

plasminogenactivatorinhibitors(suchasPAI),whichdirectlyinhibitt-PAandtheactiveformof

u-PA.

Anticoagulantmechanisms

Thereareseveralregulatorymechanismsthatnormallypreventactivatedcoagulationreactions

from causing local thrombosis or disseminated intravascular coagulation. These mechanisms

includeinhibitionandclearanceoftheactivatedcoagulationfactors,especiallyduringhepatic

circulation. The three major anticoagulant systems are tissue factor pathway inhibitor (TFPI),

antithrombinIIIandtheproteinCanticoagulantpathway(figure2).

WhileTFPIonlyinactivatesfactorVIIaboundtotissuefactor,antithrombinhasseveralpointsof

impact.ItneutralizesfactorXa,thrombin(factorIIa),factorIXaandfactorVIIaboundtotissue

factor.Alltheseactionsarethoughttobeacceleratedwhenantithrombinisboundtoheparin

orvascularheparin-likeproteoglycans.TheproteinCpathwayisactivatedwhenthrombinbinds

tothrombomodulinontheendothelialcellsurface.ThiscomplexactivatesproteinC,which,if

boundtoitscofactorproteinS,proteolyticallyinactivatesfactorsVaandVIIIa.Withoutthese

cofactors,factorXaanIXacannoteffectivelyactivatetheirsubstrates,resultinginashutoffof

thecoagulationcascade.

chaptertwo22

Activation of hemostasis during cardiopulmonary bypass (CPB)

Activationofcoagulationandfibrinolysis

Traditionally, it has been thought that contact activation via factor XII was the trigger for

extensiveactivationofthehemostaticsystemduringCPB.FactorXIIbecomesactivatedwhen

blood interacts with a foreign surface, such as the CPB circuit, thus activating the intrinsic

clottingpathway.However,Boisclairetal.showednochangeinfactorXIIalevelsduringCPB,

despitesignificantthrombingeneration,indicatingthatcontactactivationwasnottheinitial

triggerforcoagulation.3Incontrast,theyfoundalateincreaseinfactorIXactivationpeptide,

probablybysecondaryfeedbackactionofthrombin.Inagreementwiththisresults,Burmanetal.

foundthatFactorX,butnotfactorIX,wasactivated(asmeasuredbytheiractivationpeptides)

in a factor XII deficient patient, undergoing CABG with CPB.4 This activation correlated with

F1.2andthrombin-antithrombincomplexes.Thissuggestsarolefortheextrinsicpathwayas

theprimarystimuluswithsubsequentactivationoffactorIXandtheintrinsicsystemviathe

extrinsicpathway.TheextrinsicpathwayisactivatedwhenfactorVIIbindswithTFresulting

intheactivatedfactorVII(factorVIIa)/TFcomplex.TFisreleasedbytheendothelialcellsdue

to the surgical trauma and the retransfusion of pericardial blood and TF-expression on the

surfaceofactivatedmonocytesarealsosourcesforVIIa/TFactivationduringCPB.5-8Together,

thecontactactivationandtissuefactorpathwayresultintheimmenseformationofthrombin

during CPB. Activation of fibrinolysis occurs simultaneously and by several mechanisms. t-

PAreleasecontributestofibrinolysisand ispromotedbyCPB-mediatedcontactactivationof

factorXII,thrombin,hypothermia,traumatizedendothelialcellsandreturnedbloodfromthe

cardiotomysuction.9,10

Theactivationofthesecascadesmayleadtoaconsumptivecoagulopathy.11Thrombinmediates

the conversionof fibrinogen to fibrin, and also activates factor V, VII, XIII, and platelets. It

alsoactivatescomplementintheinflammatorysystem,whichmayfurtherenhancecoagulation

activation.Ontheotherhand,thrombinalsodownregulateshemostasisbyreleasingTFPIand

in combination with thrombomodulin, it activates protein C, which inhibits the previously

generatedfactorsVaandVIIIa.Thrombinalsoinitiatesfibrinolysisbymediatingreleaseoft-PA,

whichactivatesplasmin.Iftheeffectsofthrombinandplasminarenotattenuated,unrestricted

thrombinandplasminactivitywillleadtoconsumptionofcoagulationfactorsandplatelets(i.e.

adisseminatedintravascularcoagulationstateduringCPB)andthismayresultinbothbleeding

andthrombo-emboliccomplications.

Plateletdysfunction

CPB activates platelets with resultant structural and biochemical changes. Alterations in

plateletcount,clotformationandinteractionswithothercellsaredocumentedandnumerous

factorsassociatedwithCPBcontributetothesechanges.Theseincludephysicalfactors(such


ashypothermiaandhighshearstresses),exposuretoartificialsurfaces,theuseofexogenous

drugs(suchasheparinandprotamine),andthereleaseofendogenouschemicalmediators(such

asthrombin,complement,cytokinesandadrenaline).12-15Thrombocytopeniaiswelldescribedin

associationwithCPBandisnotonlytheresultofhemodilutionbutalsoofmechanicaldisruption

bytheCPBsystemandsequestrationinorgans.Also,severalplateletsurfacemoleculessuch

as GPIb and GPIIb/IIIa are downregulated during CPB, while the expression of P-selectin is

increased.16ThereleaseofsolubleP-selectinintothecirculationbyactivatedplateletsisalso

increasedduringCPB.14Allthesechangescanleadtoboththeformationofplateletconjugates

byactivatedplateletsandhemostaticdefectsduetoimpairedplateletfunction.Also,platelet-

mediatedforcedevelopmentnecessaryforplateletmediatedclotretractiontostrengthenthe

plateletplugissubstantiallylowerafterCPBthanbeforeCPB.17

ProteolysisofVWF

Inearlierstudies,theroleofVWFinCABGwithCPBhasbeenstudiedextensively.Perrinand

colleagues found a clear negative association between on the one hand VWF antigen levels

and VWF activity, and postoperative bleeding. VWF activity, as measured by both collagen

binding and ristocetin cofactor assay increased postoperatively starting 60 minutes after

theprocedure.18Otherstudiesdemonstratedthatthehighest–molecular-weight-multimersof

VWF rose to above normal levels after bypass, regardless if desmopressin acetate or placebo

was administered.19,20 Although previous studies suggested that desmopressin may reduce

postoperative blood loss, this could not be demonstrated in a double-blind, randomized,

placebo-controlledtrial.20However, inallthesestudies,VWFactivitywasonlystudiedinon-

pumppatients,mostlyindicatingthatactivityincreasedaftertheprocedure.Bylackofacontrol

group, no discrimination could be made between effects of the surgical trauma and the CPB

systemitself.ItisconceivablethatthehighshearforcesoftheCPBsystemcaninducestructural

changes in the shape of the VWF molecule, making it more sensitive for ADAMTS-13.21 This is

supportedbyPerutelli,whodemonstratedalimitedproteolysisofVWFduringCPB,asshownby

progressivechangesofmultimericstructureandsubunitcomposition.22Manucciandcolleagues

were the first to study ADAMTS-13 activity in 20 on-pump and 13 off-pump patients in a non-

randomizedfashion.TheyfoundasignificantabsolutedecreaseofADAMTS-13activityafterboth

procedures,whereasVWFantigenlevelsandVWFactivitywerebothincreased.23

Useofheparinandprotamine

TopreventthromboemboliccomplicationsduetottheuseofCPB,heparinisadministered(usually

inafixeddoseregimen)beforethepatientisconnectedtotheCPBsystem.Heparinbindstothe

enzyme inhibitor antithrombin III (AT-III) causing a conformational change which results in

its active site being exposed. This is then available for rapid interaction with thrombin. When

boundtoheparin,therateatwhichAT-IIIinactivatesthrombinandotherproteasesinvolvedin

24

bloodclotting,mostnotably factorXa, increases1000-fold.DuringCPBtheactivatedclotting

time(ACT)isusedtomonitorthelevelofheparin-inducedanticoagulationandatargetACT>450

secondsduringCPBispursued.However,theusefulnessofACTduringCPBhasbeenquestionedas

ACTvaluesdonotcorrelatewellwithplasmaheparinconcentrationsinpatientsonCPB,probably

because of the effects of hypothermia and hemodilution.11,24 Monitoring whole-blood heparin

concentrationstotitrateheparinadministrationduringCPBmaymoreeffectlysuppressexcessive

hemostaticactivation.24Nevertheless,measuringACTcurrentlyremainsthemostcommonlyused

anticoagulationstrategyduringCPBworldwide.

Nexttotheneutralizationofthrombin,heparinalsoleadstoincreasedplasmingeneration.This

resultsinincreasedfibrinolysisandalsoplateletactivation,asplasminbindstotheirsurface.

At the end of CPB, protamine sulfate is used for reversal of heparin anticoagulation. The

administrationofprotaminemayalsocauseatransientthrombocytopenia,whichisassociated

withplateletactivationandtheformationoftransientaggregatesthatappeartosequestratein

thelungs.25,26Protamine-inducedactivationofcomplementmaycontributetothiseffect.

Strategies to attenuate hemostatic activation during cardiac surgery

Numerouspharmacologicalandnon-pharmacologicalstrategieshavebeenproposedasmeansto

attenuatethealterationsinthehemostaticsystemduringCPB.

Pharmacologicalstrategies

Plateletinhibition

The perioperative continuation of aspirin has been warranted due to the fear of increased

postoperativeblood lossandtransfusionrequirements.However,Manganoetal.werethefirst

to demonstrate an effect of early antiplatelet therapy on mortality after CABG.27 In a large

multicenter trial comprising 5065 patients, they found that aspirin therapy started within 48

hoursafter revascularizationwasassociatedwithreducedmortalityandsignificantreductions

intheincidenceofmyocardialinfarction,stroke,renalfailureandbowelinfarction.Inaddition,

there was no increased risk of bleeding in these patients. Nevertheless, the perioperative use

of antiplatelet drugs during cardiac surgery remains controversial. Clopidogrel, a specific ADP-

receptor antagonist, has become the standard of care to prevent thrombotic complications

following cardiological interventions, in particular intracoronary stenting. Recent trials have

demonstratedthattheuseofclopidogrelexposure(withorwithoutconcommitantuseofaspirin)

prior to CABG surgery significantly increases the risk of postoperative bleeding, the need for

perioperativetransfusionandtheincidenceofre-exploration.28-32Incontrast,severalstudieshave

beenperformedexaminingtheefficacyof reversibleplatelet inhibitors inattenuatingplatelet

activationduringCPB.Itisexpectedthatplateletsarethusbeingpreservedpostoperativelyand

thatthismayleadtoreducedbloodlossandtransfusionrequirements.However,theresultsof

chaptertwo

thesestudiesare inconsistent. Inarandomizedtrial,CABGpatientstreatedwithdipyridamole

demonstrated a significant but small reduction in postoperative blood loss and transfusion

requirementscomparedtoplacebo.33Anotherstudydemonstratedthatashort-actingGPIIb/IIIa

antagonistmaypreservehemostasisandplateletsafterCABG.34Incontrast,otherstudiesshowed

similar or even increased blood loss and transfusion requirements in patients receiving these

typesofdrugscomparedtoplacebo.35-37

Fibrinolysisinhibitors

Tranexaminic acid (TA), ε-aminocaproic acid (EACA) and aprotinine inhibit fibrinolysis through

plasmininhibition.TAandEACAaresyntheticagentsthatadheretothelysine-bindingsitesof

plasminogen and plasmin and inhibit plasmin’s ability to digest fibrinogen, fibrin and platelet

glycoprotein receptors. These agents are regularly used during CABG to reduce postoperative

bloodlossandtransfusionrequirements.38-43

Aprotinine is a non-specific protease inhibitor with antifibrinolytic, anticoagulant, antiinflam-

matoryandplateletpreservingproperties.NexttoinhibitingfactorXIIandkallikrein-mediated

conversionofplasminogentoplasmin,italsoinhibitsactivationofboththecontactsystem(by

inactivatingkallikrein)asthetissuefactorpathway(bybindingtissuefactor-VIIacomplex).Studies

have demonstrated that patients receiving aprotinine had reduced thrombin and fibrinolytic

activity compared to placebo-treated patients.38,44 Other hemostatic features of aprotinine

reportedarepreservatedplateletintegrityandfunctionbyinhibitionofproteolyticalterationof

VWF,GPIbandGPIIb/IIIareceptors,inhibitionofproteinCactivity,andattenuationofheparin-

inducedplateletinhibition.45,46Aprotininehasshowntobeequallyeffectiveinreducingbloodloss

aftercardiacsurgeryasTAandEACA,butmightbepreferredbecauseofadditionalantiinflammatory

features.41,43However,arecentobservationalstudyin4374patientsbyManganoetal.describedan

associationbetweenaprotininandseriousend-organdamage(renalfailure,strokeandmyocardial

infarction),whichwasnotfoundwith(thelessexpensive)TAandEACA.47Reconsiderationofthe

safetyofaprotinineamongpatientsundergoingcardiacsurgerymaythereforebewarranted.

Thrombininhibitors

Severalnewlydevelopedantithromboticagentshavebeenstudiedasalternativestoheparin

when heparin cannot be used (eg, heparin-induced thrombocytopenia with thrombosis).48,49

Majorlimitationsofroutineuseofthesenewagentsincludealongpharmacodynamichalf-life

in the setting of no reversal agents, insufficient investigations regarding safety, inadequate

definitionsoftherapeuticlevelsandlackofappropriatemonitoringstrategies.

Non-pharmacologicalstrategies

Modification of techniques or mechanical devices may modify the degree of activation of

hemostasisaftercontactwiththeforeignsurfacesoftheCPBsystem.


26

Heparin-coatedCPBcircuit

AlargenumberofstudieshaveexaminedbloodlossandtransfusionrequirementsinCABGwith

heparin-coatedCPBcircuits,andconcurrentreducedheparindoses.Abouthalfofthestudies

showedareductionintransfusionrequirementswhenheparin-coatedcircuitsareused,while

the other half did not show this effect.11,50Lowering the heparin dose when heparin-bonded

circuitsareusedisnotgenerallyrecommendeduntilefficacyandsafety(lowriskofthrombo-

emboliccomplications)havebeenadequatelydetermined.

Cardiotomysuction

Ithasbeendemonstratedthatbloodinthepericardialcavityishighlyactivatedandcontainshigh

concentrationsofthrombinandplasmin.9Thisbloodisusuallycollectedbycardiotomysuction

andreroutedtothepatientwithoutprocessing.Thisunprocessedbloodcontributeshighlyto

systemicactivationofhemostasisandseveralstudiesshowedthattheuseofcardiotomysuction

results in significant increases in thrombin and platelet activation after on-pump CABG.6,9,51

In addition, cardiotomy suction causes platelet damage due to aspiration of air along with

blood.Intensecardiotomysuctionmayresultinadecreasedabilityofplateletstoaggregate.52

Omission of the use of cardiotomy suction or washing of the collected blood is advocated to

reducehemostaticactivation,butothermotives(e.g.financialconsideration)contributetothe

factthatunprocessedreinfusionofcardiotomysuctionbloodisstillfrequentlyused.

Normothermia

Hypothermic CPB resulted in more pronounced alterations of platelet aggregation and

endothelial cell related coagulation than normothermic CPB.12,53 Plasma levels of soluble

thrombomodulin were more increased in hypothermic than in normothermic CPB indicating

moreextensiveendothelialdamageoractivationassociatedwithhypothermicCPB.12However,

Stensrudetal.demonstratedthatwhentherewasnodifferenceindurationofCPB,normothermic

andhypothermicCPBgroupsdemonstratedsimilarbloodlossandtransfusionrequirements.54

Activation of hemostasis in off-pump surgery

To avoid the use of CPB and its deleterious effects on the coagulation system, off-pump

CABGhasbeenestablishedasanalternativetoon-pumpCABG.Inoff-pumpsurgery,onlythe

surgicaltraumahasaneffectonthehemostaticsystems.However,therehavebeenconcerns

about a more procoagulant activity postoperatively, that may lead to an increased rate of

thromboembolic complications.55-57 Without CPB, off-pump surgery lacks the CPB-dependent

anticoagulant properties such as platelet dysfunction and enhanced fibrinolysis, that may

counteract the procoagulant state induced by the surgical trauma.10,13,15 In addition, heparin

dosesusedintraoperativelyduringoff-pumpproceduresdosesareusuallylowerwhencompared

toconventionalCABG,astherationaleisonlytopreventperioperativegraftclosure.Asurvey

chaptertwo

27

byd’Anconaetal.showedthatonly28%of304surgeonsquestionedusedcomparabledosesfor

intraoperativeheparinizationduringoff-pumpCABG.58Themajority(54%)usedhalfthedose

of heparin during off-pump CABG (with ACT maintained above 300 seconds), while 18% used

onlyathirdofthefulldoseorhadnoprotocolatall.Inaddition,therewasalsonoconsensuson

(partialorfull)heparinreversalbyprotamineattheendofsurgeryandtheperioperativeuseof

antiplateletmedicationsuchasaspirinandclopidogrel.Thesedifferencesinanticoagulation

andantiplateletstrategiesmakeitdifficulttodeterminetheneteffectofoff-pumpsurgeryon

hemostasis.Prospectivestudiesarenecessarytodeterminetheshortandintermediateeffects

ofantiplatelettherapyandheparinizationdosesinoff-pumpCABG.

ConCLuSIon

Excessivethrombingenerationandplateletdysfunctionplayamajorroleinthedevelopmentof

abnormalitiesinhemostasisduringCPB.Numerouspharmacologicalandnon-pharmacological

strategieshavebeenproposedasmeanstoattenuatethealterationsinthehemostaticsystem

during CPB. By preserving hemostatic system components, these interventions may reduce

bleeding complications and transfusion requirements as well as thrombotic complications

in patients undergoing CPB. Off-pump CABG surgery lacks the deleterious effects of CPB on

the hemostatic system, but may be associated with a relatively more hypercoagulable state

postoperatively.

Pathophysiologyofthecoagulationsystemincardiacsurgerywithandwithouttheuseofcardiopulmonarybypass

28 References

references

1. Moake JL, Turner NA, Stathopoulos NA, Nolasco LH, Hellums JD. Involvement of large plasma von

Willebrandfactor(vWF)multimersandunusuallylargevWFformsderivedfromendothelialcellsinshear

stress-inducedplateletaggregation.JClinInvest1986;78(6):1456-1461.

2. Tsai HM, Nagel RL, Hatcher VB, Sussman II. Multimeric composition of endothelial cell-derived von

Willebrandfactor.Blood1989;73(8):2074-2076.

3.BoisclairMD,LaneDA,PhilippouH,EsnoufMP,SheikhS,HuntBetal.Mechanismsofthrombingeneration

duringsurgeryandcardiopulmonarybypass.Blood1993;82(11):3350-3357.

4.BurmanJF,ChungHI,LaneDA,PhilippouH,AdamiA,LincolnJC.RoleoffactorXIIinthrombingeneration

andfibrinolysisduringcardiopulmonarybypass.Lancet1994;344(8931):1192-1193.

5. Chung JH, Gikakis N, Rao AK, Drake TA, Colman RW, Edmunds LH, Jr. Pericardial blood activates the

extrinsic coagulation pathway during clinical cardiopulmonary bypass. Circulation 1996; 93(11):2014-

2018.

6.De SomerF, Van Belleghem Y,Caes F, Francois K,Van OverbekeH, Arnout Jetal. Tissue factor as the

mainactivatorofthecoagulationsystemduringcardiopulmonarybypass.JThoracCardiovascSurg2002;

123(5):951-958.

7.deHaanJ,BoonstraPW,TabuchiN,vanOeverenW,EbelsT.Retransfusionofthoracicwoundbloodduring

heart surgery obscures biocompatibility of the extracorporeal circuit. J Thorac Cardiovasc Surg 1996;

111(1):272-275.

8.ParrattR,HuntBJ.DirectactivationoffactorXbymonocytesoccursduringcardiopulmonarybypass.Br

JHaematol1998;101(1):40-46.

9.TabuchiN,deHaanJ,BoonstraPW,vanOeverenW.Activationoffibrinolysis inthepericardialcavity

duringcardiopulmonarybypass.JThoracCardiovascSurg1993;106(5):828-833.

10.TanakaK,TakaoM,YadaI,YuasaH,KusagawaM,DeguchiK.Alterationsincoagulationandfibrinolysis

associatedwithcardiopulmonarybypassduringopenheartsurgery.JCardiothoracAnesth1989;3(2):181-

188.

11. Despotis GJ, Joist JH. Anticoagulation and anticoagulation reversal with cardiac surgery involving

cardiopulmonarybypass:anupdate.JCardiothoracVascAnesth1999;13(4Suppl1):18-29.

12. Boldt J, Knothe C, Welters I, Dapper FL, Hempelmann G. Normothermic versus hypothermic

cardiopulmonarybypass:dochangesincoagulationdiffer?AnnThoracSurg1996;62(1):130-135.

13.KestinAS,ValeriCR,KhuriSF,LoscalzoJ,EllisPA,MacGregorHetal.Theplateletfunctiondefectof

chapter2

References 29

cardiopulmonarybypass.Blood1993;82(1):107-117.

14. Rinder CS, Bohnert J, Rinder HM, Mitchell J, Ault K, Hillman R. Platelet activation and aggregation

duringcardiopulmonarybypass.Anesthesiology1991;75(3):388-393.

15.WeerasingheA,TaylorKM.Theplateletincardiopulmonarybypass.AnnThoracSurg1998;66(6):2145-

2152.

16.RinderCS,MathewJP,RinderHM,BonanJ,AultKA,SmithBR.Modulationofplateletsurfaceadhesion

receptorsduringcardiopulmonarybypass.Anesthesiology1991;75(4):563-570.

17.GreilichPE,BrouseCF,BeckhamJ,JessenME,MartinEJ,CarrME.Reductionsinplateletcontractileforce

correlatewithdurationofcardiopulmonarybypassandbloodlossinpatientsundergoingcardiacsurgery.

ThrombRes2002;105(6):523-529.

18.PerrinEJ,RayMJ,HawsonGA.TheroleofvonWillebrandfactorinhaemostasisandbloodlossduring

andaftercardiopulmonarybypasssurgery.BloodCoagulFibrinolysis1995;6(7):650-658.

19.WeinsteinM,WareJA,TrollJ,SalzmanE.ChangesinvonWillebrandfactorduringcardiacsurgery:effect

ofdesmopressinacetate.Blood1988;71(6):1648-1655.

20.HackmannT,GascoyneRD,NaimanSC,GroweGH,BurchillLD,JamiesonWRetal.Atrialofdesmopressin

(1-desamino-8-D-argininevasopressin)toreducebloodlossinuncomplicatedcardiacsurgery.NEnglJMed

1989;321(21):1437-1443.

21.TsaiHM,SussmanII,NagelRL.ShearstressenhancestheproteolysisofvonWillebrandfactorinnormal

plasma.Blood1994;83(8):2171-2179.

22.PerutelliP.ProteolysisofvonWillebrandfactorisincreasedduringcardiopulmonarybypass.Thromb

Res2001;102(5):467-473.

23.MannucciPM,ParolariA,CancianiMT,AlemanniF,CameraM.OppositechangesofADAMTS-13andvon

Willebrandfactoraftercardiacsurgery.JThrombHaemost2005;3(2):397-399.

24. Despotis GJ, Joist JH, Hogue CW, Jr., Alsoufiev A, Joiner-Maier D, Santoro SA et al. More effective

suppression of hemostatic system activation in patients undergoing cardiac surgery by heparin dosing

basedonheparinbloodconcentrationsratherthanACT.ThrombHaemost1996;76(6):902-908.

25.KirklinJK,ChenowethDE,NaftelDC,BlackstoneEH,KirklinJW,BitranDDetal.Effectsofprotamine

administration after cardiopulmonary bypass on complement, blood elements, and the hemodynamic

state.AnnThoracSurg1986;41(2):193-199.

26.AlMondhiryH,PierceWS,BasarabRM.Protamine-inducedthrombocytopeniaandleukopenia.Thromb

Haemost1985;53(1):60-64.

30 References

27.ManganoDT.Aspirinandmortality fromcoronarybypasssurgery.NEnglJMed2002;347(17):1309-

1317.

28.EnglbergerL,FaehB,BerdatPA,EberliF,MeierB,CarrelT. Impactofclopidogrel incoronaryartery

bypassgrafting.EurJCardiothoracSurg2004;26(1):96-101.

29. Hongo RH, Ley J, Dick SE, Yee RR. The effect of clopidogrel in combination with aspirin when given

beforecoronaryarterybypassgrafting.JAmCollCardiol2002;40(2):231-237.

30.vonHeymannC,RedlichU,MoritzM,SanderM,VargasHO,GrubitzschHetal.Aspirinandclopidogrel

takenuntil2dayspriortocoronaryarterybypassgraftsurgeryisassociatedwithincreasedpostoperative

drainageloss.ThoracCardiovascSurg2005;53(6):341-345.

31. Chu MW, Wilson SR, Novick RJ, Stitt LW, Quantz MA. Does clopidogrel increase blood loss following

coronaryarterybypasssurgery?AnnThoracSurg2004;78(5):1536-1541.

32.YendeS,WunderinkRG.Effectofclopidogrelonbleedingaftercoronaryarterybypasssurgery.CritCare

Med2001;29(12):2271-2275.

33.TeohKH,FremesSE,WeiselRD,ChristakisGT,TeasdaleSJ,MadonikMMetal.Cardiacreleaseofprostacyclin

andthromboxaneA2duringcoronaryrevascularization.JThoracCardiovascSurg1987;93(1):120-126.

34. Suzuki Y, Hillyer P, Miyamoto S, Niewiarowski S, Sun L, Rao AK et al. Integrilin prevents prolonged

bleedingtimesaftercardiopulmonarybypass.AnnThoracSurg1998;66(2):373-381.

35.LincoffAM,LeNarzLA,DespotisGJ,SmithPK,BoothJE,RaymondREetal.Abciximabandbleeding

duringcoronarysurgery:resultsfromtheEPILOGandEPISTENTtrials.ImproveLong-termOutcomewith

abciximabGPIIb/IIIablockade.EvaluationofPlateletIIb/IIIaInhibitioninSTENTing.AnnThoracSurg

2000;70(2):516-526.

36. Alvarez JM. Emergency coronary bypass grafting for failed percutaneous coronary artery stenting:

increasedcostsandplatelettransfusionrequirementsaftertheuseofabciximab.JThoracCardiovascSurg

1998;115(2):472-473.

37. Gammie JS, Zenati M, Kormos RL, Hattler BG, Wei LM, Pellegrini RV et al. Abciximab and excessive

bleedinginpatientsundergoingemergencycardiacoperations.AnnThoracSurg1998;65(2):465-469.

38.KuitunenA,HiippalaS,VahteraE,RasiV,SalmenperaM.Theeffectsofaprotininandtranexamicacid

on thrombin generation and fibrinolytic response after cardiac surgery. Acta Anaesthesiol Scand 2005;

49(9):1272-1279.

39.RischA,DorscheidE,SteinG,SeyfertUT,GrundmannU.[Theeffectofaprotininandtranexamicacidon

fibrinolysisandthrombingenerationduringcardiopulmonarybypass].Anaesthesist2000;49(4):279-285.

chapter2

References 31

40.CasatiV,DellaVP,BenussiS,FrancoA,GerliC,BailiPetal.Effectsoftranexamicacidonpostoperative

bleeding and related hematochemical variables in coronary surgery: Comparison between on-pump and

off-pumptechniques.JThoracCardiovascSurg2004;128(1):83-91.

41.MunozJJ,BirkmeyerNJ,BirkmeyerJD,O’ConnorGT,DaceyLJ.Isepsilon-aminocaproicacidaseffective

asaprotinininreducingbleedingwithcardiacsurgery?:ameta-analysis.Circulation1999;99(1):81-89.

42.VanderSalmTJ,KaurS,LanceyRA,OkikeON,PezzellaAT,StahlRFetal.Reductionofbleedingafter

heart operations through the prophylactic use of epsilon-aminocaproic acid. J Thorac Cardiovasc Surg

1996;112(4):1098-1107.

43. Casati V, Guzzon D, Oppizzi M, Cossolini M, Torri G, Calori G et al. Hemostatic effects of aprotinin,

tranexamic acid and epsilon-aminocaproic acid in primary cardiac surgery. Ann Thorac Surg 1999;

68(6):2252-2256.

44.MarxG,PokarH,ReuterH,DoeringV,TilsnerV.Theeffectsofaprotininonhemostaticfunctionduring

cardiacsurgery.JCardiothoracVascAnesth1991;5(5):467-474.

45.JohnLC,ReesGM,KovacsIB.Reductionofheparinbindingtoandinhibitionofplateletsbyaprotinin.

AnnThoracSurg1993;55(5):1175-1179.

46. Boldt J, Schindler E, Osmer C, Wittstock M, Stertmann WA, Hempelmann G. Influence of different

anticoagulationregimensonplateletfunctionduringcardiacsurgery.BrJAnaesth1994;73(5):639-644.

47.ManganoDT,TudorIC,DietzelC.Theriskassociatedwithaprotininincardiacsurgery.NEnglJMed2006;

354(4):353-365.

48.KosterA,YeterR,BuzS,KuppeH,HetzerR,LincoffAMetal.Assessmentofhemostaticactivationduring

cardiopulmonary bypass for coronary artery bypass grafting with bivalirudin: results of a pilot study. J

ThoracCardiovascSurg2005;129(6):1391-1394.

49. Kanemitsu S, Nishikawa M, Onoda K, Shimono T, Shimpo H, Yazaki A et al. Pharmacologic platelet

anesthesia by glycoprotein IIb/IIIa complex antagonist and argatroban during in vitro extracorporeal

circulation.JThoracCardiovascSurg2003;126(2):428-435.

50.AldeaGS,DoursounianM,O’GaraP,TreanorP,ShapiraOM,LazarHLetal.Heparin-bondedcircuitswith

a reducedanticoagulationprotocol inprimaryCABG:aprospective, randomizedstudy.AnnThoracSurg

1996;62(2):410-417.

51. Aldea GS, Soltow LO, Chandler WL, Triggs CM, Vocelka CR, Crockett GI et al. Limitation of thrombin

generation, platelet activation, and inflammation by elimination of cardiotomy suction in patients

undergoing coronary artery bypass grafting treated with heparin-bonded circuits. J Thorac Cardiovasc

Surg2002;123(4):742-755.

32 References

52.BoersM,vandenDungenJJ,KarliczekGF,BrenkenU,vanderHeideJN,WildevuurCR.Twomembrane

oxygenatorsandabubbler:aclinicalcomparison.AnnThoracSurg1983;35(4):455-462.

53.SpezialeG,FerroniP,RuvoloG,FattouchK,PulcinelliFM,LentiLetal.Effectofnormothermicversus

hypothermic cardiopulmonary bypass on cytokine production and platelet function. J Cardiovasc Surg

(Torino)2000;41(6):819-827.

54.StensrudPE,NuttallGA,deCastroMA,AbelMD,ErethMH,OliverWC,Jr.etal.Aprospective,randomized

study of cardiopulmonary bypass temperature and blood transfusion. Ann Thorac Surg 1999; 67(3):711-

715.

55. Mariani MA, Gu YJ, Boonstra PW, Grandjean JG, van Oeveren W, Ebels T. Procoagulant activity after

off-pumpcoronaryoperation:isthecurrentanticoagulationadequate?AnnThoracSurg1999;67(5):1370-

1375.

56.QuigleyRL,FriedDW,SalengerR,PymJ,HighbloomRY.ThrombelastographicchangesinOPCABsurgical

patients.Perfusion2002;17(5):363-367.

57.QuigleyRL,FriedDW,PymJ,HighbloomRY.Off-pumpcoronaryarterybypasssurgerymayproducea

hypercoagulablepatient.HeartSurgForum2003;6(2):94-98.

58.D’AnconaG,DoniasHW,KaramanoukianRL,BergslandJ,KaramanoukianHL.OPCABtherapysurvey:

off-pumpclopidogrel,aspirinorboththerapysurvey.HeartSurgForum2001;4(4):354-358.

chapter2

References 33

Chapter three

Activation of hemostasis after coronary artery bypass grafting with or without cardiopulmonary bypass

3

Bernard Lo Md1, rob Fijnheer, Md, Phd2; domenico Castigliego2; Cornelius

Borst Md, Phd3; Cor J. Kalkman, Md, Phd1; Arno P. nierich, Md, Phd4

DepartmentofAnesthesiology1,DepartmentofHematology2,Heart-Lung

CenterUtrecht3,UniversityMedicalCenterUtrecht,Utrecht;

DepartmentofThoracicAnesthesiologyandIntensiveCare4,IsalaClinics,

Zwolle,TheNetherlands

AnesthAnalg2004Sep;99(3):634-40

chapterthree36

ABStrACt

Activationofcoagulation,fibrinolysisandthevascularendotheliumoccursafterheartsurgery

withcardiopulmonarybypass(CPB),buttheeffectsofeliminatingCPBinpatientsundergoing

coronaryarterybypassgrafting(CABG)isunknown.Therefore,wecomparedhemostaticprofiles

ofoff-pumpandon-pumpCABGpatients.Twogroupsofconsecutivepatientsparticipatingina

largertrial(theOctopusStudy)wererandomlyallocatedtoundergoCABGwith(n=20)orwithout

CPB(n=20).PlateletnumberandplasmaconcentrationsofP-selectin,prothrombinfragments

1.2(F1.2),solublefibrin,D-dimersandvonWillebrandFactor(VWF,asamarkerofendothelial

cellactivation)weremeasuredandcorrectedforhemodilution.Comparedtotheon-pumpCABG

group,F1.2andD-dimerlevelsweresignificantlylower(p=0.004andp=0.03,respectively)in

patientshavingCABGsurgeryperformedoff-pump.IntheCPBgroup,F1.2(median(interquartile

range):450%ofbaseline,(233-847%)andD-dimer(538%(318-1192%),peakedintheimmediate

postoperativeperiod,andremainedelevateduptoday4,whileintheoff-pumpgroupF1.2and

D-dimer levels rose more gradually and were highest on day 4 (342% (248-515%) and 555%

(387-882%)respectively).Inbothgroups,VWFconcentrationswereelevateduptoday4(CPB:

308% (228-405%), off-pump: 288% (167-334%)). Despite heparinization, CABG surgery with

CPBwasassociatedwithexcessive thrombingenerationandfibrinolyticactivity immediately

postoperatively. The off-pump group demonstrated a delayed postoperative response that

becameequalinmagnitudetotheCPBinthelater(20and96hours)postoperativeperiod.

Activationofhemostasisaftercoronaryarterybypassgraftingwithorwithoutcardiopulmonarybypass 37

IntroduCtIon

Coronaryarterybypassgrafting(CABG)withcardiopulmonarybypass(CPB)isassociatedwith

intense activation of hemostatic mechanisms.1-3 Both extensive contact between blood and

nonendothelialsurfacesofthebypasscircuitandthereleaseandreinfusionoftissuefactorlead

toincreasedthrombingenerationduringtheCPBprocedure.2-4Thisresultsinfibrinformation,

fibrinolysis and platelet activation despite full heparinization.2,5,6 As a part of the systemic

inflammatory response, hemostatic activation may lead to generation of microthrombi and

maycontribute toCPB-relatedorgandysfunction.7-9Anothermorecommoncomplicationdue

tohemostaticactivationafterCPBisabnormalpostoperativebleeding,asabnormalactivation

ofthehemostaticsystemcanleadtoconsumptionofcoagulationfactors,increasedfibrinolysis

anddestructionofplatelets.5,10

Theperformanceofoff-pumpCABG(OPCAB)mightofferhemostaticadvantageswhencompared

with the need for CPB during routine CABG surgery. Eliminating exposure of blood to the

extracorporealcircuitcouldreducehemostaticdefects.Clinically,reducedpostoperativeblood

loss and lower transfusion requirements have been reported in comparison to conventional

CABG with CPB.11 On the other hand, major surgical trauma may also lead to activation of

hemostasisandrecentstudiessuggestthatoff-pumpCABGsurgerycanleadtoaprocoagulant

state,possiblycontributingtoearlythromboticcomplications.1,12-17

Therehavebeennorandomizedtrialsthatdirectlycomparedperioperativehemostaticvariables

inthesetwotypesofsurgery.Recently,ourhospitalparticipatedinarandomizedtrialcomparing

neurocognitive dysfunction after on-pump and off-pump procedures (the Octopus-trial).18,19

Usingpatientsfromthistrial,wecomparedchangesincoagulation,fibrinolysisandendothelial

cellactivationduringCABGsurgerywithorwithoutCPBinaprospectiverandomizedstudy.

chapterthree38

MetHodS

Patients

Patients with stable angina pectoris (Braunwald Class I-II, a-c) were eligible for the Octopus

Trial,arandomizedtrialcomparingtheeffectsofoff-pumpversuson-pumpcardiacsurgeryon

neurocognitivedysfunction.19Afterobtaininginformedconsent,patientswererandomizedbya

telephonecalloftherandomizationcenteroftheJuliusCenterforGeneralPracticeandPatient

Oriented Research, Utrecht to undergo CABG with CPB or without CPB. For our study, blood

samplesof40subsequentpatientsoftheOctopusTrialwerecollectedandanalyzed(CPBgroup;

n=20,off-pumpgroup;n=20).Thestudywasapprovedbythelocalethicalandresearchcouncil.

IntheCPBgroup,anesthesiawasinducedwithmidazolam(0.1mg/kg),sufentanil(2-3μg/kg)

andpancuronium(0.1mg/kg)andmaintainedwithacombinationofmidazolam(0.1mg/kg.h)

and sufentanil (0.5 μg/kg.h). Anesthetic management for off-pump coronary surgery and the

Octopus-trialhasbeendescribedindetailrecently.18,20Inshort,anesthesiawasachievedwith

sufentanil (2-3 μg/kg at induction and continued at 0.25-0.5 μg/kg.h), propofol (2 mg/kg at

induction and continued at 2-3 mg/kg.h) and pancuronium (0.1 mg/kg). Anticoagulation or

antiplatelettherapywasdiscontinued7daysbeforesurgery.TheCPBpatientsreceived1mg/kg

dexamethasoneafterinductionofanesthesia.Inbothgroups,surgicalaccesstotheheartwas

achievedbymidsternalincision.

In theCPBgroup, theextracorporealcircuitconsistedofamembraneoxygenatoranda roller

pump. Only the oxygenator and the venous reservoir (Baxter Healthcare Corporation, Irvine

CA,USA)werepartiallyheparin-coated.BeforeconnectiontoCPB,porcineheparin(300IU/kg,

HeparinLeo,LeoPharmaceuticalProductsBV,Weesp,theNetherlands)wasadministeredinorder

to achieve an activated coagulation time (ACT) of more than 450 seconds. CPB was managed

accordingtotheα-statprinciple,withaminimalnasopharyngealtemperatureof32oCandCPB

flowratewaskeptat2.4L/min.m2.Myocardialprotectionwasachievedwithcold(4°C)potassium

cardioplegia(Plegisol,AbbottInc,Chicago,IL,USA).DuringCPB,bloodwasrecollectedusinga

suctioncardiotomyreservoir,andwithoutprocessingreinfusedtotheCPBsystem.Attheendof

CPB,heparinwasneutralizedby3mg/kgprotaminechloride(Hoffman/LaRoche,Mijdrecht,the

Netherlands)andadditionalprotaminewasadministereduntiltheACTwasbelow150s.

Intheoff-pumpgroup,coronarybypassgraftingwasperformedonthebeating,normothermic

heart with local cardiac wall immobilization using the Octopus Tissue Stabilizer (Medtronic,

Minneapolis, MN, USA). Before starting the anastomosis, porcine heparin (150 IU/kg) was

administered in order to achieve an ACT of more than 250 seconds. A cell-saver was used to

reducetheneedforbloodtransfusion.Attheendoftheoperation,protamine(25-50mg)was

administeredifanACT>150swasmeasured.

Intraoperativetransfusionprotocolsweredifferentforbothgroups.IntheCPBgroup,hematocrit

waskeptabove22%duringCPB,whileintheoff-pumpgrouphematocritwaskeptabove25%.A


lowerhematocritwasacceptedintheCPBgroupduetothedilutionaleffectoftheprimingofthe

CPBsystem,theuseofcrystalloidSt.Thomascardioplegicsolutionandhypothermiaduringthe

procedure.Postoperativetransfusiontriggerwasahematocritof28%inbothgroups.

Requirementsforintraoperativeandpostoperativeallogenicbloodtransfusionsandtheamount

ofpostoperativebleedinginthefirst12hoursaftersurgerywererecordedinallpatients.Major

complicationssuchasmyocardialinfarctionorstrokewereassessedandhavebeendescribedin

detailrecently.18

Postoperativepatienttreatmentintheintensivecareunitwassimilarforbothgroups.Ifchest

tubedrainagewasmorethan150mL/hinthefirsthouror100mL/hfortwosuccessivehours,

ACT was measured and additional protamine was administered if ACT > 150 s. Hypertension

wastreatedwithnicardipine.Thrombosisprophylaxisconsistedofnadroparin2850IU(Sanofi

Winthrop,Maassluis,theNetherlands)subcutaneouslythedaybeforesurgeryandacetylsalicylic

acid80mgdailywasstartedonthefirstpostoperativeday.

WeusedadifferenttargetACTforbothprocedures,asthereweredifferentindicationsforthe

use of anticoagulation. While in the CPB group heparin was mainly used to prevent clotting

in the CPB system, in the off-pump group it was needed to prevent clotting in the harvested

internalmammarianarteriesandinthenativecoronarysystemduringgrafting.Nevertheless,

thepostoperativeACT(<150s,afterprotamineinfusion)wasthesameinbothgroups.Asthese

factors mostly influence perioperative coagulation and hypothesizing that off-pump surgery

wouldnotinfluencehemostasis,wedecidedtostudyonlytheeffectsafterthesurgery,leaving

outintra-operativedifferences.

Blood Sampling and Laboratory Assays

Bloodsamplesweredrawnatthefollowingintervals:afterinductionofanesthesia(pre-OR),at

theendofthesurgicalprocedureafterreversalofheparinduringwoundclosure(end-OR)and

2,20and96hourslater.Allsampleswereimmediatelycooledoniceandcentrifugedtwiceat

2000*Gfor15minutes.Plasmawasstoredat–80°C.

Platelet counts were determined with an automatic cell counter (Cobas Minos ST, Roche,

Montpellier,France).

ActivationofplateletswasassessedbythereleaseofsolubleP-selectin(sP-selectin),quantified

byELISAwithspecificmonoclonalrabbitantibodies(R&DSystemsLtd,Abingdon,UK).P-selectin

arisesfromalphagranulesandisreleasedwhentheyfusewiththeplateletmembrane.Thrombin

generationwasassessedbythemeasurementsofF1.2(proteolyticfragmentofprothrombin),

analyzedbyELISA(EnzygnostF1.2micro,BehringwerkeAG,Frankfurt,Germany)andsoluble

fibrin (proteolysis of fibrinogen by thrombin, studied by an ELISA technique (Diagnostica &

Analys,Senice,AB,USA)).FibrinolysiswasassessedbythemeasurementofD-dimerformation

(DiagnosticaStago,Roche,Mannheim,Germany).D-dimersarederivedfromthelysisofcross-

linked fibrin in contrast to split products that arise from the lysis of non-cross-linked fibrin.

chapterthree40

ConcentrationsofvonWillebrandFactor(VWF),asamarkerofendothelialcellactivation,were

determinedbyanELISAasdescribedpreviously.21

PrimingoftheCPBcircuitresultsinacutehemodilutionimmediatelyafterthestartofCPB.To

correctforresultanthemodilutionintheCPBgroup,causedbyadministrationofcrystalloidor

colloidsolutionsandCPBpriming,wequantitatedImmunoglobulinG(IgG)byanephelometric

method(DadeBehring,Leusden,theNetherlands).Avolumecorrectionofallobtaineddata(of

bothgroups)wasmadebasedontheratiooftheplasmalevelsofIgG.1Thereafter,thevaluesof

eachparameterweretransformedtopercentageswithrespecttothepre-operativelevel.

Statistical Analysis

(Posthoc)calculationofsamplesize,basedonadesireddecreaseinkeyparametersofthrombin

generation(F1.2)andfibrinolysis(D-dimer)by50%,andapowerof0.9at α=0.05,resultedin19

patientsforeachgroup.Inourstudy,atotalof40patientswereincluded.Alldataarepresented

asmean± standarddeviation(SD)orasmedian(and interquartile range).TheFriedmantest

wasusedtocomparelongitudinalchangesovertimeinbothpatientgroups.Whensignificant

differenceswereobserved,thesewerefurtherevaluatedbyusingtheWilcoxonmatchedpairs

test for comparison between baseline and consecutive time points. A general linear model

for repeated measurements was used to detect overall treatment effects. When significant

differenceswereobserved,thesewerefurtherevaluatedbyusingtheMann-WhitneyU-testto

assessintergroupdifferencesatasinglepredeterminedtimepoint.

While using the repeated measurementsmodel and the Friedman test, a p-value of less than

0.05wasconsideredsignificant.Toaccommodateformultipletestingwithfurtherevaluation,

differenceswereconsideredsignificantatp-valueslessthan0.01.

reSuLtS

Clinical Characteristics

PatientcharacteristicsarelistedinTable1.Demographicoroperativeparametersweresimilarin

bothgroups,exceptfortheuseofheparinandprotamine.Onlyfouroff-pumppatientsreceived

protamine (25-50 mg) at the end of the procedure. There were no significant differences in

postoperative parameters at discharge such as mediastinal drainage, use of blood products

and hemoglobin concentration. None of the patients received desmopressin acetate or anti-

fibrinolytic medication. There were no perioperative deaths or major complications such as

myocardialinfarctionorstroke.

TheabsoluteplasmalevelsofIgGandthehemostaticvariablesaresummarizedinTable2.The

volumecorrected,relativevaluesofF1.2,solublefibrinandD-dimersaredisplayedinFigure1.


Activation of Coagulation

We could demonstrate an overall significant difference over time for F1.2 concentrations

betweenthetwotreatments(P=0.03)butnot forsolublefibrin.IntheCPBgroup,F1.2 levels

peakedto450%(233-847%)intheimmediatepostoperativeperiodandstayedelevatedupto

day 4 (P<0.001 at all time points compared to baseline), whereas in the off-pump group F1.2

levels were significantly elevated from 2 hours after surgery (308% (168-485%); P=0.006

comparedtobaseline)andmeasuredhighestonday4(342%(248-515%);P<0.001comparedto

baseline)(Figure1).Levelsofsolublefibrinweresignificantlyelevateduptoday4inbothgroups

comparedtopreoperatively(CPB:160%(69-398%);P<0.001,off-pumpgroup:198%(122-309%);

P=0.002)(Figure1).

Activation of Fibrinolysis

IntheCPBgroup,wecouldshowadifferentchangeinD-dimerlevelsovertimethanintheoff-

pumpgroup(P=0.004).IntheCPBgroup,plasmaconcentrationsofD-dimerspeakedimmediately

postoperatively(538%(318-1192%))andremainedelevateduptoday4,whereasintheoff-pump

grouplevelsincreasedgraduallyfrom137%(118-199%)immediatelypostoperativelyupto555%

(387-882%)onday4(Figure1).Inbothgroups,postoperativeD-dimerslevelswereelevatedat

alltimepointscomparedtobaseline(P<0.001,Figure1).

Platelet Activation and endothelial Cell Activation

SolubleP-selectinconcentrationswerecorrectedforthenumberofcirculatingplatelets.22Asan

indicatorofplateletactivationandrelease,nodifferencescouldbedemonstratedinP-selectin

concentrationsbetweenthetwogroups.Inbothgroups,sP-selectinlevelswereelevatedwith

apeakof187%(96-261%)at2hourspostoperativelyintheCPBgroup,andapeakof133%(96-

195%)intheoff-pumpgroup.Atday4,levelshadreturnedtobaselineinbothgroups.

Immediatelyaftersurgery,thenumberofplateletshaddecreasedto60%ofbaselinelevelinthe

CPBgroup.Whencorrectedfordilution,however,plateletcountsweresimilartotheoff-pump

group.Atday4,thequantityofcirculatingplateletshadincreasedsignificantlytoapproximately

130%inbothgroups,withoutintergroupdifference.

TherewerenodifferencesinpostoperativelevelsofVWFbetweenthegroups.Inbothgroups,

plasmaconcentrationswereelevatedcomparedtobaselineduringtheentireobservationperiod,

reachingmaximumlevelsatday4aftertheoperation(CPBgroup:308%(228-405%);P<0.001

comparedtobaseline,off-pump:288%(167-334%);P<0.001comparedtobaseline).

chapterthree42

dISCuSSIon

In this prospective, randomized study of off-pump versus on-pump coronary artery bypass

surgery we found two temporally different patterns: the CPB group had a significantly more

pronounced activation of coagulation and fibrinolysis in the immediate postoperative period,

whereastheoff-pumpgroupdemonstratedadelayedpostoperativeresponsethatbecameequal

in magnitude to the CPB group in the later (20 and 96 hours) postoperative period. Levels of

VWFwereelevatedfromthefirstpostoperativedayafterbothsurgicalproceduresandpeaked

at high levels on the fourth postoperative day. Further research is needed to determine what

perioperativeanticoagulationregimenismostappropriateforbothon-andoff-pumpsurgery.

Cardiopulmonary Bypass response

Despite the use of commonly accepted methods of anticoagulation and heparin reversal, we

foundevidenceofmarkedincreasesinthrombin(F1.2)activityintheearlypostoperativeperiod

in patients undergoing CABG surgery with CPB. The demonstration of significant elevations

in fibrinolytic activity (D-dimer levels) at the same time suggests that this may be, in part, a

response(secondary)toexcessivethrombinactivity.DuringCPB,thrombinisgeneratedviathe

contactsystemactivationaswellasviatheliberationoftissuefactor.2,3,5Thelatterisreleased

bythecuttingofbloodvesselsorintroducedbyreinfusionofcardiotomysuctionbloodduring

bypass.2Activatedmonocytesinthewoundbloodhavebeenshowntoexpresstissuefactoron

thesurfacewhenexposedtothepericardialcavity.3Consequently,unprocessedpericardialblood,

thatisroutedbacktothebypasssystem,ishighlyactivatedandcouldproduceaprocoagulant

state.3Washingthecollectedbloodbymeansofacell-savingdevice,willreducetheamountof

proinflammatorycytokinesandtheprocoagulantpropertiesofthereturnedblood,althoughit

cannoteliminateitentirely.4

Our findings are in accordance with other studies showing massive activation of hemostasis

duringandearlyaftercardiacsurgeryperformedwiththeuseofCPB.1,12Theonlyrecentstudy

that compared coagulation and fibrinolysis in on-pump and off-pump CABG directly was a

nonrandomizedtrialbyCasatietal.whichshowedasimilartransientincreaseinD-dimerlevels

immediately postoperatively in the CPB group compared to off-pump.1 However, the authors

only measured up to 24 hours postoperatively. In contrast to our study, they also found that

CPBwasassociatedwithlowerplateletcountsandlowerplasminogenlevels.Althoughwecould

demonstratemarkedplateletactivationdirectlypostoperatively,asdemonstratedbyplasmaP-

selectinperplatelet,itwasnotsignificantlydifferentbetweenbothgroups,norcouldwedetect

apostoperativedecreaseinplateletnumberaftercorrectionforhemodilution.

Theactivatedstateofhemostasisimmediatelyafteron-pumpsurgery,asevidencedbyelevated

F1.2 and D-dimer concentrations, may reflect the formation of microthrombi and could

theoreticallycontributetotheorgandysfunction,associatedwithCPB.8,9Immediatelyafteroff-


table 1. Peri-operative Characteristics

Variable CPB Group off-pump Group P-value

(n=20) (n=20)

Age(years) 64±11 63±9 0.725

Sex(M/F) 16/4 12/8 0.108

Bodysurfacearea(m2) 1.94±0.16 1.89±0.18 0.947

BodyMassIndex(kg/m2) 27.0±3.6 25.9±2.3 0.134

Heparin(x1,000IU) 24.4±3.7 15.5±4.5 <0.0001

CPBduration(min) 81±34 0

ACCduration(min) 50±19 0

Protamine(mg) 254±32 9±18 <0.0001

No.ofvenousgrafts 0(0-1) 0(0-1) 0.681

No.ofarterialgrafts 2(2-3) 2(2-3) 0.502

Bloodlossinf irst12H(mL) 500(370-605) 625(400-1003) 0.113

TotalbloodlossICU(mL) 610(445-890) 845(463-1198) 0.175

PRBCOR,units(patientstransfused) 8(4) 4(2) 0.376

TotalPRBC,units(patientstransfused) 12(6) 19(10) 0.197

FFPOR,units(patientstransfused) 0(0) 0(0) 1.000

TotalFFP,units(patientstransfused) 3(1) 6(3) 0.292

TotalPLTC,units(patientstransfused) 0(0) 0(0) 1.000

Postoperativehemoglobin(g/dL) 10.8±1.6 9.8±1.3 0.091

Dataarepresentedasmean±SDormedian(interquartilerange).CPB,cardiopulmonarybypass;ACC,aorticcross-

clamping;ICU,intensivecareunit;OR,operatingroom;PRBC,packedredbloodcells;FFP,freshfrozenplasma;PLTC,

plateletconcentrate

chapterthree44

table 2. Laboratory variables during coronary artery bypass surgery, uncorrected for dilution

Variable Pre-or end-or 2 H 20 H day 4

F1.2 CPB 1.7(1.1-2.0) 5.7(3.5-8.0) 4.9(4.1-10.2) 2.7(2.1-4.5) 5.6(4.3-6.2)

(µg/mL) off-p. 2.1(1.1-2.8) 2.0(1.1-3.2) 3.7(2.4-4.6) 3.0(2.4-4.0) 6.0(5.0-7.7)

fibrin CPB 144(95-372) 401(221-588) 269(182-576) 259(182-483) 298(184-503)

(µg/mL) off-p. 66(35-117) 59(42-128) 136(52-182) 184(85-271) 97(69-247)

d-dim. CPB 236(177-364) 1402(680-1915)1443(857-2120) 865(652-1125) 1120(809-1476)

(µg/L) off-p. 200(153-292) 318(181-420) 626(478-820) 773(633-858) 1263(1115-1493)

Plt cnt. CPB 190(173-234) 112(105-138) 130(128-175) 167(128-194) 242(184-279)

(109/L) off-p. 170(144-175) 189(133-231) 170(114-237) 162(108-222) 255(185-299)

P-sel/plt CPB 0.72(0.52-1.06) 1.29(0.96-1.49) 1.20(1.04-1.53) 1.12(0.85-1.54) 0.64(0.40-0.88)

(fg) off-p. 0.84(0.54-1.49) 0.97(0.55-1.63) 1.39(0.59-1.90) 1.32(0.79-1.66) 0.71(0.51-1.03)

VWF CPB 9.0(7.5-13.7) 7.8(6.1-11.5) 8.7(7.0-10.5) 13.5(8.6-19.1) 28.6(21.9-34.4)

(µg/mL) off-p. 10.1(8.5-11.8) 10.7(8.6-13.7) 14.3(11.6-17.8) 14.5(11.5-20.4) 23.8(20.0-32.6)

IgG CPB 6.5(4.1-7.3) 3.9(3.3-4.6) 4.5(3.8-5.6) 5.3(4.0-6.0) 5.8(4.5-6.8)

(g/l) off-p. 6.5(5.3-8.3) 5.0(4.3-6.8) 4.6(3.8-5.6) 4.7(4.2-5.8) 6.2(5.1-7.8)

Pre-OR,preoperativeatinduction;End-OR,endofoperation;H,hoursafteroperation;F1.2,prothrombinfragments1.2;

CPB,cardiopulmonarybypassgroup;off-p.,off-pumpgroup;D-dim,D-dimers;Pltcnt.,plateletcount;P-sel/plt,P-selectin

perplatelet;VWF,vonWillebrandFactor;IgG,ImmunoglobulinG

Allvariablesareexpressedasmedianandinterquartilerange


0

200

400

600

800

1000

1200

1400

Pre-OR End-OR 2 H 20 H Day 4

(%)

0

100

200

300

400

500

600

700

800

900


(%)

0

200

400

600

800

1000

1200


(%)

D-dimers

Soluble fibrinProthrombin fragment 1.2

D-dimers

**

**

**

**

‡

**

**

**

**

****

‡

‡

**

**

**

**

†CPBoff-pump

CPBoff-pump

CPBoff-pump

**

**

*

**

**

*

Figure 1.Markersofthrombingenerationandf ibrinolysis.Relativeplasmalevelsofprothrombinfragments1.2andsolublef ibrin(throm-

bingeneration)andD-dimers(f ibrinolysis)inpatientsundergoingCABG,eitherwithCPB(CPBgroup,whitebars)orwithoutCPB(off-pump

group,hatchedbars).Datahavebeencorrectedforhemodilutionandareexpressedin%ofpreoperativevaluesandpresentedasmedian

andinterquartilerange.

* indicatesp<0.01and** indicatesp<0.001betweenpre-operativeandfollowingtimeeventswithinonegroup.†meansp<0.01and‡

meansp<0.001betweengroupsatonetimepoint.Pre-OR,preoperativeatinduction;End-OR,endofoperation;H,hoursafteroperation.

chapterthree46

pumpsurgerythereismuchlesshemostaticactivation,andthismayhavebeenacontributing

factorinthebetterreportedclinicaloutcome.9,23Moreover,lessconsumptionofclottingfactors

mayexplainthereducedpostoperativebloodlossandtransfusionrequirementsthathavebeen

reportedinoff-pumpsurgery.10,11However,thiswillneedtobeconfirmedinlargerstudies.

Surgical trauma response

Wefoundasignificantincreaseinthrombinandfibrinolyticactivityinthelate(20hrs,4days)

postoperative period. Thrombin generation persisted as reflected in a second or maintained

increaseofF1.2,withasimilarincreaseofD-dimerformation.

These findings confirm previous reports of an increased procoagulant activity in the first

postoperativedaysafteroff-pumpsurgery.1,14,15Whereasthepotentialhypercoagulablestateis

opposedbyadministrationofintravenousheparinandhemodilutioninstandardCABG,dosesof

heparinandfluidsgivenduringoff-pumpsurgeryareusuallylower.Quigleyetal.demonstrated

a twofold increase in coagulation index in off-pump patients 72 hours postoperatively,

indicatingastateofrelativehypercoagulability,whereasinpatientsundergoingstandardCABG

the coagulation had returned to preoperative values.15This procoagulant activity in the days

following off-pump surgery may lead to increased risk for early thrombotic complications like

graftocclusion.16,17 IthasbeenshownthatOPCABgraftshave lowerpatencyratesthangrafts

implanted by conventional techniques and limited revascularization, which results in more

frequentreinterventions.4,24Standardsforperioperativeheparinizationandantiplatelettherapy

inoff-pumpsurgeryarestilllackingbutareusuallylessaggressivethaninon-pumpsurgery.25

Therefore,furtherresearchisneededtodeterminewhatperioperativeanticoagulationregimens

ismostappropriateforoff-pumpsurgery.

LevelsofVWFwereelevatedfromthefirstpostoperativedayafterbothsurgicalproceduresand

peakedathighlevelsonthefourthpostoperativeday.PlasmaVWFisoneofthemostusefulmarkers

forvascularendothelialactivationasitisaspecific,stable,circulatingproductoftheendothelial

cell.21 Forming a part of a molecular bridge between platelets and the subendothelium of an

injuredvesselwall,inthepresenceofraisedplasmaVWFlevels,plateletadhesionconsequently

canbeincreasedbeyondnormal.Therefore,theincreasedreleaseofVWFcouldhavecontributed

toincreasedthrombogenicityinbothsurgicalgroupsduringthefirstdaysaftersurgery.

Limitations of the study

Althoughthepresentstudyisarandomized(singlecenter)trial,ithasseverallimitations.The

numberofpatients israthersmall,so itshouldbeconsideredmoreasapilot investigationto

directthemostappropriateanalysesofcoagulationparametersinalargercohort.Asthesmall

samplesizeprecludesexcludingtypeIIerror,smalldifferencesbetweenthegroupsatcertain

time points could have been missed. In addition to that, the number of sampling periods is

limited,soonlydatafromthesepredefinedsamplingperiodscanbesupplied,possiblymissing


hemostatic abnormalities at other time points after CABG. Secondly, the Octopus study was

designed as a practical rather than an explanatory trial: it compared off-pump surgery with

conventionalCABGbothperformedaswhatwasconsideredstandardpracticeintheNetherlands

atthattime.Thisincludedadditionalfactorsassociatedwiththeon-pumpprocedurethatcould

haveinfluencedourresults.Theseinclude:1)useofdexamethasone(tomitigatethesystemic

inflammatoryresponse)2)useofmoderatehypothermia3)useofcardioplegiatoarresttheheart

and4)useofdifferentanticoagulationstrategies(targetACT>450svs250s).Wealsouseda

fixedprotaminedosageforheparinreversal.AsACTmaybeinfluencedbyotherfactorssuchas

hypothermiaandhemodilution, itmaynotaccuratelyreflecttheextentofanticoagulationby

heparin.5Thiscouldhaveledtorelativeprotamineoverdoseandthereforemighthaveinfluenced

ourresultsintheimmediatepostoperativeperiod.5Inaddition,anACT<150sintheoff-pump

groupmaystillhaverepresentedsignificantanticoagulation(aPTT>100s).Monitoringofwhole

bloodheparinconcentrationsoradministrationofheparinbasedonaCPBduration-dependent,

fixeddoseregimenmighthelpavoidthisandwouldbepreferableinfuturestudies.Itisclearly

established that patient specific heparin dosing leads to less hemostatic activation, better

thrombininhibitionandlesstransfusionofallogenicblood.5,26Usingmonitoringofwholeblood

heparin concentrations during CPB could probably decrease or even abolish the pronounced

activation of coagulation and fibrinolysis we demonstrated in the immediate postoperative

period.However,atthismomentmeasuringACTisstillthemostcommonlyusedanticoagulation

strategyduringcardiacsurgery.

ConCLuSIon

Thisprospective,randomizedstudyprovidesevidencethatCPBisassociatedwithasignificantly

more pronounced activation of coagulation and fibrinolysis in the immediate postoperative

period.Intheoff-pumpgroupadelayedpostoperativeresponsewasdemonstrated,thatbecame

equalinmagnitudetotheCPBgroupinthelater(20and96hours)postoperativeperiod.Levels

ofVWFwereelevatedfromthefirstpostoperativedayafterbothsurgicalproceduresandpeaked

at high levels on the fourth postoperative day. Further research is needed to determine what

perioperativeanticoagulationregimensismostappropriateforbothon-andoff-pumpsurgery.

chapterthree48

references

1.CasatiV,GerliC,FrancoA,DellaVP,BenussiS,AlfieriOetal.ActivationofCoagulationandFibrinolysis

duringCoronarySurgery:On-pumpversusOff-pumpTechniques.Anesthesiology2001;95(5):1103-1109.

2.BoisclairMD,LaneDA,PhilippouH,EsnoufMP,SheikhS,HuntBetal.Mechanismsofthrombingeneration

duringsurgeryandcardiopulmonarybypass.Blood1993;82(11):3350-3357.

3. Chung JH, Gikakis N, Rao AK, Drake TA, Colman RW, Edmunds LH, Jr. Pericardial blood activates the

extrinsic coagulation pathway during clinical cardiopulmonary bypass. Circulation 1996; 93(11):2014-

2018.

4.TabuchiN,SunamoriM,KoyamaT,ShibamiyaA.Remainingprocoagulantpropertyofwoundbloodwashed

byacell-savingdevice.AnnThoracSurg2001;71(5):1749-1750.

5. Despotis GJ, Joist JH. Anticoagulation and anticoagulation reversal with cardiac surgery involving

cardiopulmonarybypass:anupdate.JCardiothoracVascAnesth1999;13(4Suppl1):18-29.

6.RinderCS,BohnertJ,RinderHM,MitchellJ,AultK,HillmanR.Plateletactivationandaggregationduring

cardiopulmonarybypass.Anesthesiology1991;75(3):388-393.

7. Butler J, Rocker GM, Westaby S. Inflammatory response to cardiopulmonary bypass. Ann Thorac Surg

1993;55(2):552-559.

8. Roach GW, Kanchuger M, Mangano CM, Newman M, Nussmeier N, Wolman R et al. Adverse cerebral

outcomesaftercoronarybypasssurgery.MulticenterStudyofPerioperativeIschemiaResearchGroupand

theIschemiaResearchandEducationFoundationInvestigators.NEnglJMed1996;335(25):1857-1863.

9. Ascione R, Lloyd CT, Underwood MJ, Gomes WJ, Angelini GD. On-pump versus off-pump coronary

revascularization:evaluationofrenalfunction.AnnThoracSurg1999;68(2):493-498.

10.HollowayDS,SummariaL,SandesaraJ,VagherJP,AlexanderJC,CapriniJA.Decreasedplateletnumber

andfunctionandincreasedfibrinolysiscontributetopostoperativebleedingincardiopulmonarybypass

patients.ThrombHaemost1988;59(1):62-67.

11.AscioneR,WilliamsS,LloydCT,SundaramoorthiT,PitsisAA,AngeliniGD.Reducedpostoperativeblood

loss and transfusion requirement after beating-heart coronary operations: a prospective randomized

study.JThoracCardiovascSurg2001;121(4):689-696.

12.HuntBJ,ParrattRN,SegalHC,SheikhS,KallisP,YacoubM.Activationofcoagulationandfibrinolysis

duringcardiothoracicoperations.AnnThoracSurg1998;65(3):712-718.

13. Samama CM, Thiry D, Elalamy I, Diaby M, Guillosson JJ, Kieffer E et al. Perioperative activation of

hemostasisinvascularsurgerypatients.Anesthesiology2001;94(1):74-78.


14.MarianiMA,GuYJ,BoonstraPW,GrandjeanJG,vanOeverenW,EbelsT.Procoagulantactivityafteroff-

pumpcoronaryoperation:isthecurrentanticoagulationadequate?AnnThoracSurg1999;67(5):1370-1375.

15.QuigleyRL,FriedDW,SalengerR,PymJ,HighbloomRY.ThrombelastographicchangesinOPCABsurgical

patients.Perfusion2002;17(5):363-367.

16.ZehrKJ,HandaN,BonillaLF,AbelMD,HolmesDR,Jr.Pitfallsandresultsofimmediateangiographyafter

off-pumpcoronaryarterybypassgrafting.HeartSurgForum2000;3(4):293-299.

17.KimKB,LimC,LeeC,ChaeIH,OhBH,LeeMMetal.Off-pumpcoronaryarterybypassmaydecreasethe

patencyofsaphenousveingrafts.AnnThoracSurg2001;72(3):S1033-S1037.

18.vanDijkD,NierichAP,JansenEW,NathoeHM,SuykerWJ,DiephuisJCetal.Earlyoutcomeafteroff-pump

versuson-pumpcoronarybypasssurgery:resultsfromarandomizedstudy.Circulation2001;104(15):1761-

1766.



1412.

20.NierichAP,DiephuisJ,JansenEW,BorstC,KnapeJT.Heartdisplacementduringoff-pumpCABG:how

wellisittolerated?AnnThoracSurg2000;70(2):466-472.

21.vanMourikJA,BoertjesR,HuisveldIA,FijnvandraatK,PajkrtD,vanGenderenPJetal.vonWillebrand

factorpropeptideinvasculardisorders:Atooltodistinguishbetweenacuteandchronicendothelialcell

perturbation.Blood1999;94(1):179-185.

22.FijnheerR,FrijnsCJ,KortewegJ,RommesH,PetersJH,SixmaJJetal.TheoriginofP-selectinasa

circulatingplasmaprotein.ThrombHaemost1997;77(6):1081-1085.

23.MageeMJ,JablonskiKA,StamouSC,PfisterAJ,DeweyTM,DullumMKetal.Eliminationofcardiopulmonary

bypass improves early survival for multivessel coronary artery bypass patients. Ann Thorac Surg 2002;

73(4):1196-1202.

24.GundrySR,RomanoMA,ShattuckOH,RazzoukAJ,BaileyLL.Seven-yearfollow-upofcoronaryartery

bypassesperformedwithandwithoutcardiopulmonarybypass.JThoracCardiovascSurg1998;115(6):1273-

1277.

25.D’AnconaG,DoniasHW,KaramanoukianRL,BergslandJ,KaramanoukianHL.OPCABtherapysurvey:off-

pumpclopidogrel,aspirinorboththerapysurvey.HeartSurgForum2001;4(4):354-358.

26. Koster A, Fischer T, Praus M, Haberzettl H, KueblerWM, Hetzer R, et al. Hemostatic activation and

inflammatoryresponseduringcardiopulmonarybypass: impactofheparinmanagement.Anesthesiology

2002;97(4);837-41.

Chapter four

Activation of hemostasis is associated with early cognitive decline after off-pump coronary artery bypass surgery

4

Bernard Lo Md1; rob Fijnheer, Md, Phd2; Arno P. nierich, Md, Phd3;

Cor J. Kalkman, Md, Phd*; diederik van dijk, Md, Phd1

DepartmentofAnesthesiology1,DepartmentofHematology2,

UniversityMedicalCenterUtrecht,Utrecht;

DepartmentofThoracicAnesthesiologyandIntensiveCare3,

IsalaClinics,Zwolle,TheNetherlands

JThrombHaemost2005Sep;3(9):2114-7

chapterfour52

ABStrACt

Background and objectives

Severalstudieshaveshownthatcognitivedeclinealsooccursafteroff-pumpcoronaryartery

bypass grafting, suggesting that other factors than the use of cardiopulmonary bypass

contributetocognitivedecline.Wehypothesizedthatahypercoagulablestateafteroff-pump

surgerymaycontributetocognitivedecline.

Patients and methods

Inasampleof60consecutivepatientsundergoingoff-pumpcoronaryarterybypasssurgery,

westudiedtheassociationbetweenpostoperativeactivationofhemostasis,asreflectedbyD-

dimers and prothrombin fragments1.2 (F1.2)andcognitiveoutcomeat the 4thday, 3and 12

monthsaftersurgery.

results

D-dimer and F1.2 levels at two hours after the off-pump procedure were strongly associated

withcognitivedeclineonpostoperativeday4(p=0.004andp=0.013,respectively).Alsoina

multivariate logistic regression model, postoperative D-dimer levels were a strong predictor

of early cognitive decline. No association was found between postoperative activation of

hemostasisandcognitiveoutcomeafter3and12months.

Conclusions

OurdataindicatethatearlypostoperativeD-dimerandF1.2levelsassociatedwithearlycognitive

outcomeafteroff-pumpcoronaryarterybypasssurgery.Activationofhemostasismaytherefore

contributetocognitivedeclineinoff-pumpsurgery.

Activationofhemostasisisassociatedwithearlycognitivedeclineafteroff-pumpcoronaryarterybypasssurgery 53

IntroduCtIon

Cognitive dysfunction after coronary artery bypass grafting (CABG) is a well-recognized

complicationandhasbeenlargelyattributedtotheuseofthecardiopulmonarybypass(CPB)

system.1,2However,severalstudieshavedemonstratedthatoff-pumpCABGisalsoassociated

withcognitivedecline,suggestingthatotherfactorsthantheuseofCPBcancontributetothis

complication.3,4Recently,wedemonstratedthatoff-pumpCABGisassociatedwithpostoperative

activation of hemostasis to a similarextentas conventionalCABG in the later postoperative

period.5 This postoperative hypercoagulable state, which has also been demonstrated by

others6mayleadtotemporaryocclusionofbloodvesselsandthuscontributetopostoperative

organdamage.

Wehypothesizedthatapostoperativehypercoagulablestateafteroff-pumpCABG,asreflected

byD-dimersandprothrombinfragments1.2(F1.2),maybeassociatedwithearlypostoperative

cognitivedecline.

chapterfour54

PAtIentS And MetHodS

Blood sampling

Perioperative blood samples (after induction of anesthesia, 2 and 96 hours after the end of

thesurgicalprocedure)fordeterminationofD-dimerandF1.2levelswerecollectedfromsixty

off-pumppatientswhoparticipatedintheOctopus-study.3Therewasnoadditionalselection

criteria entry for this study. Design and methods of the Octopus multicenter trial have been

describedindetailelsewhere3.PlasmaD-dimersandF1.2levelswereassessedbyquantitative

enzymeimmunoassaysaccordingtothemanufacturers’instructions(AsserachromD-dimerkit,

Diagnostica Stago, Roche, Mannheim, Germany and Enzygnost F1.2 Micro, Behringwerke AG,

Frankfurt,Germany,respectively).

Cognitive outcome

Toestablishearlycognitiveoutcome,patientsunderwentabatteryofsixneuropsychologicaltests

(theReyauditoryverballearningtest,thegroovedpegboard,thetrailmakingtest,theSternberg

memorycomparison,thelineorientationtestandtheStroopcolourwordtest)onedaybefore

andfourdaysaftersurgery.Inaccordancewiththe“Statementofconsensusonassessmentof

neurobehavorialoutcomesaftercardiacsurgery”7thebatterytestedmotorskills,verbalmemory

capacityandattention.Eachtestyieldedoneormorevariables,withdifferentrangesforeach

variable.Sevenmainvariableswerechosenaprioritobeusedintheanalyses.“Cognitivedecline”

was defined, according to commonly used criteria, as a decrease in the person’s performance

ofatleast20%frombaselineperformancebeforesurgery,inatleast20%(thatis,two)ofthe

mainvariables.8Patientswhohadhadastrokewereconsideredtohavecognitivedecline.Three

andtwelvemonthsaftersurgery,cognitiveperformancewasdeterminedwithamoreextended

batteryof10neuropsychologicaltests.3

data analysis

ThepredictiveassociationbetweenpostoperativeD-dimerandF1.2levelsandcognitivedecline

wasquantifiedusingOddsRatios(OR)and95%confidenceintervals(CI).Toaccountforother

possiblepredictorsofpostoperativecognitivedecline,multivariatelogisticregressionanalysis

wasapplied.Theseotherpredictorswereage,sex,thepresenceofdiabetesmellitus,peripheral

vasculardisease,historyofstrokeortransient ischaemicattack,andthenumberofdiseased

arteries. In addition, other possible confounders such as intubation time, use of thoracic

epidural analgesia and postoperative CRP levels (as a marker of inflammatory or acute phase

response)wereincluded.Firsttheassociationbetweenearlycognitivedeclineandeachofthe

otherpossiblepredictorswasquantifiedbyunivariateanalysis.Then,allpredictorswithp≤0.25

in the univariate analysis were included in a multivariate logistic regression model together

withpostoperativeD-dimerandF1.2levels.Todemonstrateadose-responserelationshipthe


studycohortwasdividedinquartilesbasedonpostoperativeD-dimerlevels.

reSuLtS

Twopatientswereexcludedbecausetheyhadaperioperativemyocardialinfarction.Preoperative

D-dimer and F1.2 levels were comparable between patients with and without early cognitive

decline (D-dimer: 0.3 (0.1-0.4) versus 0.2 (0.1-0.3) µg/mL and F1.2: 0.7 (0.5-0.9) versus 0.7

(0.4-0.9)nmol/L,respectively).Twohoursaftertheoperation,D-dimerlevelsweresignificantly

increased inbothgroupsbuthigher inpatientswithearlycognitivedecline than inpatients

without early cognitive decline (0.9 (0.6-1.6) versus 0.6 (0.3-0.9) µg/mL; p = 0.002). At this

timepoint,F1.2levelswerealsohigherinpatientswithearlycognitivedecline(1.5(1.2-1.7)

versus 1.1 (0.9-1.3) nmol/L; p=0.006). At the fourth postoperative day, D-dimer levels were

significantlyelevatedbutcomparableinbothgroups(nodecline:1.95(1.24-2.44)µg/mLversus

decline:2.21(1.38-2.55)µg/mL;p=0.45)andthisalsoaccountedforF1.2levels(nodecline:1.7

(1.5-2.2)nmol/Lversusdecline:1.7(1.4-2.0)nmol/L;p=0.86).

WhenpatientsweredividedinquartilesbasedonD-dimerlevels2hoursaftertheoperation,

therewasacleardose-responserelationshipbetweenpostoperativeD-dimerlevelsandearly

cognitivedecline(Table1).Thiscouldnotbedemonstratedforthecognitivedeclineafter3and

12months.

BothearlypostoperativeD-dimerlevelsasF1.2levelswereapredictorofearlycognitivedecline

(p=0.004andp=0.013,respectively).Table2showstheresultsoftheunivariateandmultivariate

logisticregression.Aftercorrectionforotherpredictorsorpossibleconfounders,theassociation

betweenpostoperativeD-dimerlevelsandearlycognitivedeclinewasstillpresent(p=0.02).No

associationcouldbedemonstratedbetweenearlypostoperativeD-dimerlevelsandcognitive

declineat3and12months(univariateanalysis:p=0.39andp=0.41,respectively).

chapterfour56

table 1. Quartiles of post-operative d-dimer levels (at 2 hours) in off-pump CABG and cognitive decline

d-dimer level Cognitive decline in no. of patients (%)

range (median) Postoperative day 4 3 months 1 year

(µg/mL)

Group 1 0.23-0.39 (0.29) 3/15(20) 2/15(13) 2/15(13)

Group 2 0.42-0.68 (0.58) 5/15(33) 3/14(21) 4/13(31)

Group 3 0.73-1.06 (0.84) 6/13(46) 2/13(15) 6/13(46)

Group 4 1.17-3.00 (1.58) 10/15(67) 3/13(23) 5/13(39)

Total 0.23-3.00 (0.70) 24/58(41) 10/55(18) 17/54(31)


table 2. early cognitive decline by logistic regression analysis

Predictor decline decline univariate Multivariate

absent present analysis analysis

(n=34) (n=24) or p-value or p-value

Age,mean(SD)(years) 62(8) 62(8) 0.99 0.78

Femalesex(%) 38 33 0.81 0.70

Diabetes(%) 9 13 1.53 0.65

Peripheralvasculardisease(%) 3 12 4.71 0.19 3.66 0.83

PreviousstrokeofTIA(%) 3 0 0.79

Hypertension(%) 47 42 0.80 0.68

Numberofdiseasedcoronaryarteries2.1 2.0 1.29 0.50

Useofsideclamp(s)(%) 32 21 0.44 0.50

D-dimerlevels2hpostop(µg/mL) 0.6(0.3-0.9) 0.9(0.6-1.6) 1.0018 0.004 1.0022 0.02

F1.2levels2hpostop(nmol/L) 1.1(0.9-1.3) 1.5(1.2-1.7) 13.1 0.013 2.2 0.56

TimeinOperatingRoom(SD)(h) 4.2(0.9) 4.2(1.1) 1.02 0.94

Useofbloodproducts(%) 3 0 0.79

TotalbloodlossinICU(SD)(mL) 692(375) 631(416) 1.00 0.70

Intubationtime(SD)(h) 8.0(3.9) 8.6(4.8) 1.03 0.62

Useofcellsaver(%) 31 46 1.95 0.21 1.42 0.74

ThoracicEpiduralAnalgesia(%) 71 63 0.69 0.52

CRPlevels20hpostop(mg/L)(SD) 85.9(48.2) 91.7(48.0) 1.00 0.93 1.00 1.00

OR,OddsRatio;SD,standarddeviation;TIA,transientischemicattack;ICU,IntensiveCareUnit

chapterfour58

dISCuSSIon

Inthepresentstudy,wearethefirsttodemonstrateanassociationbetweenearlyactivationof

hemostasisafteroff-pumpsurgeryandearlypostoperativecognitivedecline.Thisassociation

deserves further investigation. Intraoperative activation of hemostasis in off-pump CABG

is significantly less to that in conventional CABG. The coagulation and fibrinolysis cascades,

however,areactivatedaftertheprocedure,aswitheverymajoroperation.6Inanearlierstudy,

we foundthatpostoperativeactivationofhemostasisafteroff-pumpandconventionalCABG

become comparable after the first postoperative day.5 This postoperative hypercoagulable

state or “preservedhemostasis”may contribute to thrombo-emboliccomplications likegraft

occlusion.9Anewstudy,specificallydesignedtoquantifycoagulativestateandneurocognitive

outcome,isneededtoconfirmthepresentresults.

Hypercoagulability may not be the only source of cognitive decline after off-pump surgery.

Exposureoftheposteriorcardiacwallfrequentlyleadstotransientepisodesofelevatedcentral

venous pressure and concurrent decreased systemic blood pressure, resulting in a decreased

cerebral perfusion pressure.10 Also the formation of intra-operative microemboli from aortic

manipulation,whentangentialaorticcrossclamping isusedduring the off-pumpprocedure,

maycontributetothedevelopmentofcognitivedecline.11Thesemechanismsmayexplainthe

incidenceofcognitivedeclineinthelowerD-dimergroups(Table1).

AlthoughwefoundaclearassociationbetweenearlypostoperativeD-dimerlevelsandcognitive

decline 4 days after the operation, no relation was found with cognitive decline after 3 and

12 months. The incidence after 3 and 12 months may have been too low to detect such an

association in this small study. However, several studies demonstrated that early cognitive

decline is an independent predictor of both incidence and severity of cognitive decline after

several months or years.2,12 Moreover, our study participants were relatively young, and they

might recover better from the cognitive decline in the early postoperative period. Effects of

hemostatic activation on long-term cognitive decline may be more notable in older patients

withmoreco-morbidity.

Inconclusion,earlypostoperativeD-dimerandF1.2levelsareassociatedwithearlycognitive

outcomeafteroff-pumpCABG.Activationofhemostasismaythereforecontributetocognitive

declineinoff-pumpsurgery.

references

1.vanDijkD,KeizerAM,DiephuisJC,DurandC,VosLJ,HijmanR.Neurocognitivedysfunctionaftercoronary

arterybypasssurgery:asystematicreview.JThoracCardiovascSurg2000;120(4):632-639.

2.NewmanMF,KirchnerJL,Phillips-ButeB,GaverV,GrocottH,JonesRHetal.Longitudinalassessmentof

neurocognitivefunctionaftercoronary-arterybypasssurgery.NEnglJMed2001;344(6):395-402.



1412.

4. Lloyd CT, Ascione R, Underwood MJ, Gardner F, Black A, Angelini GD. Serum S-100 protein release

and neuropsychologic outcome during coronary revascularization on the beating heart: a prospective

randomizedstudy.JThoracCardiovascSurg2000;119(1):148-154.

5.LoB,FijnheerR,CastigliegoD,BorstC,KalkmanCJ,NierichAP.Activationofhemostasisaftercoronary

arterybypassgraftingwithorwithoutcardiopulmonarybypass.AnesthAnalg2004;99(3):634-640.

6.MarianiMA,GuYJ,BoonstraPW,GrandjeanJG,vanOeverenW,EbelsT.Procoagulantactivityafteroff-

pump coronary operation: is the current anticoagulation adequate? Ann Thorac Surg 1999; 67(5):1370-

1375.

7. Murkin JM, Newman SP, Stump DA, Blumenthal JA. Statement of consensus on assessment of

neurobehavioraloutcomesaftercardiacsurgery.AnnThoracSurg1995;59(5):1289-1295.

8. Stump DA. Selection and clinical significance of neuropsychologic tests. Ann Thorac Surg 1995;

59(5):1340-1344.

9.KimKB,LimC,LeeC,ChaeIH,OhBH,LeeMMetal.Off-pumpcoronaryarterybypassmaydecreasethe

patencyofsaphenousveingrafts.AnnThoracSurg2001;72(3):S1033-S1037.

10.NierichAP,DiephuisJ,JansenEW,BorstC,KnapeJT.Heartdisplacementduringoff-pumpCABG:how

wellisittolerated?AnnThoracSurg2000;70(2):466-472.

11.KapetanakisEI,StamouSC,DullumMK,HillPC,HaileE,BoyceSWetal.Theimpactofaorticmanipulation

onneurologicoutcomesaftercoronaryarterybypasssurgery:arisk-adjustedstudy.AnnThoracSurg2004;

78(5):1564-1571.

12.vanDijkD,MoonsKG,KeizerAM,JansenEW,HijmanR,DiephuisJC,etal.Associationbetweenearly

and three month cognitive outcome after off-pump and on-pump coronary bypass surgery. Heart 2004;

90(4):431-434.

References 59

Chapter five

relatively increased von Willebrand Factor activity after off-pump coronary artery bypass graft surgery

5

Bernard Lo Md1; Arno P. nierich, Md; Phd2; Cor J. Kalkman, Md, Phd1;

rob Fijnheer, Md, Phd3,4

DepartmentofAnesthesiology1,DepartmentofHematology3,

UniversityMedicalCenterUtrecht,Utrecht;


IsalaClinics,Zwolle

DepartmentofInternalMedicine4,JeroenBoschCenter,‘sHertogenbosch,

TheNetherlands

AcceptedbyThrombHaemost2007

chapterfive62

SuMMAry

HighshearforcescaninducestructuralchangesintheshapeofthevonWillebrandFactor

(VWF) molecule, making it more sensitive for ADAMTS-13, a specif ic VWF protease. This

leads to proteolysis of the highest–molecular-weight multimers, which are the most

effective in platelet-mediated hemostasis under conditions of high shear stress. The use

ofcardiopulmonarybypass(CPB)isaccompaniedwithhighshearforcesandcouldtherefore

leadtodiminishedVWFactivity.Therefore,westudiedVWFactivityinpatientsundergoing

myocardialrevascularization.

Weenrolled60patientsundergoingcoronaryarterybypassgraft(CABG)surgerywithand

without CPB (30 each group). ADAMTS-13 activity, VWF antigen (VWF:Ag) and propeptide

levelsweremeasureddirectlybeforeandaftertheprocedure.VWFactivitywasdetermined

using both the ristocetin cofactor activity (VWF:Rcof) and collagen binding (VWF:CB)

assays.

VWF:Rcof and VWF:CB, both corrected for VWF:Ag, were signif icantly increased after

the procedure in the off-pump group (respectively; p<0.001 and p=0.05), but not in the

CPB group. Postoperative VWF:Ag and VWF-propeptide levels signif icantly increased in

both groups. ADAMTS-13 activity increased after both types of surgery after correction

for hemodilution. Postoperative VWF:Rcof levels correlated with postoperative D-dimer

levels (p=0.025) and were associated with early cognitive decline in the off-pump group

(p=0.025).

OurdataindicatethatVWFactivityisincreasedafteroff-pumpCABG,butnotafterCABGwith

CPB. Since release of VWF is comparable in both groups, shear–stress induced proteolysis

duetotheuseofCPBmayberesponsibleforthedecreasedVWFactivity.

IntroduCtIon

VonWillebrandFactor(VWF),amultimericplasmaglycoproteinplaysanimportantrolein

primary hemostasis as it is involved in the initial adhesion of blood platelets at sites of

vascular injury.1VWFcanbindtobothexposedcollagenandtheglycoprotein Ib receptor

on platelets, hereby allowing platelet tethering at the site of injury. This is essential to

initiate thrombus formation on vascular surfaces exposed to rapidly flowing blood.2 VWF

is synthesized by megakaryocytes and endothelial cells, and released in the form of a

gigantic,multimericproteinof20,000-kDainsize.Theproteolysisofthematuremolecule

by ADAMTS-13, a plasma metalloprotease, down-regulates the size of plasma VWF to a

series of multimers ranging from 450 to over 10,000 kDa.3 This steady state distribution

of multimers reflects an equilibrium between the secretion of large multimers and their

proteolysisintosmallerinactivederivatives.

HighshearforcescaninducestructuralchangesintheshapeoftheVWFmolecule,making

itmoresensitiveforADAMTS-13.4,5Thisleadstotheproteolysisofthehighest–molecular-

weight multimers, which are the most effective in platelet-mediated hemostasis under

conditionsofhighshearstress.2Subsequently,anincreasedbleedingtendencymaydevelop,

resemblingvonWillebranddiseasetype2A.Thissyndromeischaracterizedbytheselective

absenceoflargemultimers,duetoamutationinVWF,whichincreasesitssusceptibilityto

ADAMTS-13.1 Recently, it was demonstrated that acquired von Willebrand disease type 2A

is common in patients with severe aortic stenosis. The passing of the blood through the

stenoticvalveleadstohighshearforcesresultinginproteolysisofthehighest-molecular-

weightmultimersofVWFandaconsequentbleedingtendency.6

The question arises, if shear stress-induced cleavage of VWF causes hemostatic defects

in other non-physiological flow conditions. The use of cardiopulmonary bypass (CPB) is

associated with hemostatic abnormalities due to several mechanisms such as impaired

platelet function and activation of coagulation and f ibrinolysis.7-9 However, as VWF is of

great importance in maintaining primary hemostasis, its changes due to the turbulent,

high-pressure blood flow may be another contributing factor. Therefore, we studied VWF

activity in patients undergoing coronary artery bypass graft (CABG) surgery with and

withoutcardiopulmonarybypass.

RelativelyincreasedvonWillebrandFactoractivityafteroff-pumpcoronaryarterybypassgraftsurgery 63

chapterfive64

MAterIAL And MetHodS

Patients PerioperativebloodsamplesfordeterminationofVWFactivitywerecollectedfrom60patients

whoparticipatedintheOctopus-study.10-12Therewerenoadditionalselectioncriteriaentry

forthisstudy.DesignandmethodsoftheOctopusmulticentertrialhavebeendescribedin

detailelsewhere.10-12Inshort,allparticipantshadstableanginapectoris(BraunwaldClassI-

II,a-c)andwererandomLyallocatedtoundergoCABGwith(on-pumpgroup;n=30)orwithout

use of CPB (off-pump; n=30). Patients were excluded in case of emergency or concomitant

majorsurgery,Q-wavemyocardialinfarctionintheprevious6weeks,orpoorleftventricular

function. The local ethical and research council approved the study and written informed

consentwasobtainedfromallpatients.

Thegoalofsurgerywastoobtaincompletearterialrevascularization.Withtheexceptionof

emergencyproceduresalloperationswereperformedbycardiacsurgeonsexperiencedinboth

off-pumpandon-pumpbypasssurgery.IntheCPBgroup,patientsreceivedtotalintravenous

anesthesia,includinghigh-doseopioids(sufentanil2-3μg/kgatinduction,continuedwith0.5

μg/kg⋅huntiltheendofsurgery),whereasintheoff–pumpgroup75%ofthepatientsreceived

thoracicepiduralanesthesiacombinedwith low-dose intravenousopioids(sufentanil0.25-

0.5μg/kgatinduction).TheCPBpatientsreceived1mg/kgdexamethasoneafterinductionof

anesthesia.Surgicalaccesstotheheartwasinbothgroupsachievedbymidsternalincision.

In the CPB group, the extracorporeal circuit consisted of a membrane oxygenator with

integratedheatexchanger,venousreservoirandpolyvinyltubingsystemandanon-pulsatile

rollerpump(BaxterHealthcareCorporation,Irvine,CA,USA)andwasprimedwithcrystalloid-

colloidmixture.Onlytheoxygenatorandthevenousreservoirwereheparin-coated.Before

connection to the CPB system, porcine heparin (300 IU/kg, Leo Pharmaceutical Products

BV,Weesp,TheNetherlands)wasadministeredinordertoachieveanactivatedcoagulation

time (ACT) > 450 s (Hemochron 400, International Technidyne Corp., NJ, USA). CPB was

managedaccordingtothe α-statprinciple,withaminimalnasopharyngealtemperatureof

32oC,CPBflowratewaskeptat2.4L/min⋅m2.Myocardialprotectionwasachievedwithcold

(4oC)potassiumcardioplegia(Plegisol,AbbottInc,Chicago,IL,USA).Aftercompletionofall

distalanastomoses,theaorticcross-clampwasremovedandtheproximalanastomoseswere

performed with a partial occluding clamp. Meanwhile, the patient was rewarmed to 37°C.

Heparinwasneutralizedby3mg/kgprotaminechloride(Hoffman/LaRocheB.V,Mijdrecht,

The Netherlands). To reduce blood loss, blood was recollected with a suction cardiotomy

reservoirintheon-pumpgroup,whereasacell-saverwasusedintheoff-pumpgroup.

In the off-pump group, after median sternotomy, CABG was performed on the beating,

normothermic heart with local cardiac wall immobilization by using the Octopus Tissue

Stabilizer (Medtronic, Inc., Minneapolis, MN, USA). Before start of the anastomosis,


porcineheparin(150IU/kg)wasadministeredinordertoachieveanACT>250s.Heparin

wasneutralizedby1mg/kgprotaminechloride.

Thrombosisprophylaxiswasinitiatedwithnadroparin2850IUsubcutaneouslyandcombined

withacetylsalicylicacid80mgdaily.Asprophylaxisforpostoperativeatrialf ibrillationall

patientsweregivensotalol40mgtwicedailyfromthef irstdaytill1monthaftersurgery.

Blood Collection and StorageBloodwasanticoagulatedwithcitrate(9partsblood:1part0.109Mtrisodiumcitrate)and

centrifugedat4oCfor20minat2000g.Theplasmawasremovedandrecentrifugedat4oC

for20minat2000gtoremoveresidualplatelets.Sampleswerestoredinaliquotsat–80oC

untilanalysed.

Laboratory assaysVWF antigen (VWF:Ag), VWF collagen binding activity (VWF:CB) and VWF-propeptide

antigenlevelsweremeasuredbyenzyme-linkedimmunosorbentassay(ELISA)asdescribed

previously.13-15VWFristocetincofactoractivity(VWF:Rcof)wascarriedoutbyaggregometry

using f ixed human platelets.16 The results of VWF:Rcof, VWF-CB and VWF-propeptide are

expressed in ratios of VWF:Ag. ADAMTS-13 activity was determined using a fluorescence

resonance energy transfer (FRET) assay as described previously.17 Platelet counts were

determined with an automatic cell counter (Cobas Minos ST; Roche, Montpellier, France).

Normalpoolplasmaof30healthydonorsservedasstandardforalltests.

TocorrectforhemodilutionintheCPBgroupbytheadministrationofcrystalloidorcolloid

solutions and CPB priming, pre- and postoperative hematocrit values were used. Volume

correction of VWF:Ag and ADAMTS-13 activity levels (in both groups) was made based on

the ratio of the hematocrit values and were transformed to percentage with respect to

the preoperative level. All other data were already expressed in relation to VWF:Ag and

thereforecorrectionforhemodilutionwasnotneeded.

Statistical AnalysisAll analyses were done using standard computer software (SPSS 9.0, SPSS Inc. Chicago,

IL,USA).NormalityofthedistributionofcontinuousvariableswastestedbytheShapiro-

Wilk test. All data are presented as mean ± standard deviation (SD) or as medians (and

interquartileranges(IQR))fornon-normallydistributedcontinuousvariables.Differences

in continuous and categorized variables were tested by unpaired t-test and chi-square

test,respectively.Pre-andpostoperativevalueswerecomparedusingthepairedt-testor

Wilcoxonmatchedpairssignedranksumtest.Differencesbetweenmeanswereconsidered

signif icantwhenp<0.05.

chapterfive66

reSuLtS

Patient characteristics are listed in Table 1. None of the patients received desmopressin

acetate or anti-fibrinolytic medication. There were no perioperative deaths, and no major

complications such as stroke or myocardial infarction were reported. One CPB patient was

transfusedwithredbloodcellunitsduringtheoperationandwasexcludedonlyintheanalysis

forvolumecorrecteddata.

VWF antigen and activity Mean preoperative VWF:Ag levels were comparable in both the cardiopulmonary bypass and

theoff-pumpgroup(10.3±3.3µg/mLand10.9±3.0µg/mL,respectively;p=0.42)(Table2).

PostoperativeVWF:AglevelsdroppedsignificantlyintheCPBgroup(8.8±3.0µg/mL;p=0.001

compared to preoperative levels) whereas in the off-pump group postoperative VWF antigen

levels were comparable to preoperative values (11.2 ± 3.4 µg/mL; p=0.59). However, after

correctionforhemodilution,VWF:Aglevelssignificantlyincreasedinbothgroupstothesame

extent(CPBgroup:152±42%andoff-pumpgroup:143±24%;p<0.001inbothgroupscompared

topre-operativelevels;p=0.34betweenbothgroups)(Table2).

Beforetheoperation,VWF:Rcoflevelswerecomparableinbothgroups(CPBgroup:0.91±0.17

versusoff-pumpgroup:0.85±0.17;p=0.25)(Table2).Postoperatively,VWF:Rcoflevelsdidnot

changeintheCPBgroup(0.94±0.24;p=0.36comparedtopreoperativevalue),butsignificantly

increased after the procedure in the off-pump group (1.02 ± 0.19; p<0.001 compared to

preoperativevalue).ThischangeinVWF:Rcofwassignificantlydifferentbetweenthetwogroups

(p=0.017)(Table2).Similarresults,althoughlesspronouncedwerefoundintheVWF:CBassay.

IntheCPBgroupnodifferencecouldbedemonstrated(0.97±0.07preoperativelyversus0.97±

0.08postoperatively;p=0.58),whileintheoff-pumpgroup,therewasa(borderline)significant

increasefrom0.94±0.06preoperativelyto0.98±0.09postoperatively(p=0.05)(Table2).

Aftertheoperation,VWF-propeptideratiosincreasedsignificantlyinbothgroupstoasimilar

extent(CPBgroup:from0.09±0.03to0.14±0.04;p<0.001andoff-pumpgroup:from0.10±

0.04to0.13±0.04;p=0.007),indicatingthattheendothelialreleaseofVWFduetothesurgical

traumawascomparable(Table2).

In both groups, ADAMTS-13 activity decreased significantly after the operation but more

pronouncedintheCPBgroup(CPBgroup:from80±16%to53±16%;p<0.001andoff-pump

group: from 83 ± 17% to 76 ± 18%; p<0.001). However, after correction for hemodilution

ADAMTS-13 activity was increased after both procedures (CPB group: from 80± 16% to 89 ±

23%;p=0.008andoff-pumpgroup:from83±17%to103±20%;p<0.001;p=0.07betweenboth

groups)butnottothesameextentastheincreaseinVWF:Ag.TheratioofADAMTS-13toVWF:

Agdecreasedinbothgroups(CPBgroup:from0.87±0.36to0.68±0.35;p<0.001andoff-pump

group:from0.82±0.32to0.73±0.28;p=0.002;p=0.06betweengroups)(Table2).


table 1. Peri-operative Characteristics

Variable Bypass group off-pump group P-value

(n=30) (n=30)

Age(years) 59 ±10 63 ±8 0.11

Malesex(%) 77 76 1.00

BodyMassIndex(kg/m2) 27.6 ±3.1 27.5±2.9 0.96

Hypertension(%) 57 38 0.20

Peripheralvasculardisease(%) 10 3 0.61

Smoking(%) 63 67 0.79

Diabetes(%) 13 7 0.67

Hypercholesterolaemia(%) 67 69 1.00

No.ofvesselsdiseased 2(1-3) 2(1-3) 0.75

CPBduration(min) 71 ±28

ACCduration(min) 48 ±17

ORduration(hours) 4.0 ± 0.6 4.5± 0.8 <0.01

Bloodloss,f irst12hours(mL) 378(268-500) 420(265-545) 0.62

Totalbloodloss 580(484-734) 578(433-794) 0.76

Data are presented as mean ± standard deviation or median (interquartile range). CPB, cardiopulmonary bypass;

ACC,aorticcross-clamping;ICU,intensivecareunit;OR,operatingroom;

chapterfive68

table 2. Laboratory values during Coronary Artery Bypass Surgery

Variable Before surgery end of surgery P-value

VWF:Ag (%)* 0.34†

CPB 100(=10.3±3.3µg/mL) 152±42 <0.001

Off-pump 100(=10.9±3.0µg/mL) 143±24 <0.001

VWF: rcof** 0.017†

CPB 0.91±0.17 0.94±0.24 0.25

Off-pump 0.85±0.17 1.02±0.19 <0.001

VWF:CB** 0.34†

CPB 0.97±0.07 0.97±0.08 0.58

Off-pump 0.94±0.06 0.98±0.09 0.05

VWF-propeptide antigen** 0.39†

CPB 0.09±0.03 0.14±0.04 <0.001

Off-pump 0.10±0.04 0.13±0.04 0.007

AdAMtS-13 activity (%)* 0.07†

CPB 80±16 89±23 0.008

Off-pump 83±17 103±20 <0.001

AdAMtS-13 activity/VWF:Ag** 0.06†

CPB 0.87±0.36 0.68±0.35 <0.001

Off-pump 0.82±0.32 0.73±0.28 0.002

VWF:Ag,VonWillebrandfactorantigen;CPB,cardiopulmonarybypass;VWF:Rcof,VWFristocetincofactoractivity;

VWF:CB,VWFcollagenbindingactivity

*correctedforhemodilutionusinghematocritvalues,**ratios,correctedforVWF:Aglevels†p-valuesbetweengroups


Platelet countPreoperativeplateletcountswere198±45·109/Lintheoff-pumpgroupand196±38·109/L

intheCPBgroup.Attheendofsurgery,plateletcountssignif icantlydroppedto186±48

·109/L (p=0.03) in the off-pump group and to 129 ± 36 ·109/L in the CPB group (p<0.001).

However, after correction for hemodilution using hematocrit levels, preoperative and

postoperativeplateletcountswerecomparableinbothgroups.Onthef irstpostoperative

day(20hoursaftersurgery),plateletcountsweresignif icantly lowerthanbeforesurgery

in the off-pump group (185 ± 55 ·109/L, p=0.03), while platelet counts in the CPB group

returned to preoperative values (199 ± 45 ·109/L, p=0.48; p =0.03 between off-pump and

CPBgroup).

Correlation with early postoperative cognitive declineIn a previous study, we demonstrated that postoperative activation of hemostasis was

associatedwithearlyneurocognitivedeclineafteroff-pumpsurgery.18Inthepresentoff-

pumpgroup(whichisasubsetofthepreviousstudy)wefoundapositivecorrelationbetween

postoperativeVWF:RcoflevelsandearlypostoperativeD-dimerlevels(r=0.423;p=0.025).

Moreover,off-pumppatientswithearlypostoperativedeclinehadsignif icanthigherVWF:

Rcoflevelsbothbeforeandaftertheoperationthanpatientswithnoearlypostoperative

decline(0.99±0.14versus0.85±0.13;p=0.025and1.17±0.21versus0.97±0.16;p=0.025,

respectively)(Figure1).VWF:CBlevelsfollowedthesametrend,butourstudydidnothave

enoughstatisticalpowertoshowasignif icantdifferenceinVWF:CBlevelsaswell(decline

versusnodecline;preoperativeVWF:CBlevels;1.00±0.05versus0.95±0.07;p=0.07and

postoperativeVWF:CBlevels;1.02±0.06versus0.95±0.10;p=0.07,respectively).

dISCuSSIon

OurdataindicatethatVWFactivityisincreasedafteroff-pumpCABG,butnotafterCABGwith

CPB. Since release of VWF is comparable in both groups, shear–stress induced proteolysis

duetotheuseofCPBmayberesponsible.

InthepresentstudywefoundthatpostoperativeVWFlevelsweresignif icantlyincreasedto

asimilarextentinbothgroups,aftercorrectionforhemodilution.Apparently,thesurgical

traumainbothgroupsiscomparable,leadingtoequalreleaseofVWFfromendothelialcells.

This is furthersupportedby thecomparable increase inVWF-propeptideratiosafterboth

procedures.

In theoff-pumpgroup,wedemonstrated thatVWFactivity,asmeasuredbyVWF:Rcofand

VWF:CBlevels,wassignif icantlyincreaseddirectlyaftertheprocedure.Thissuggeststhat

the surgical trauma increases the release of VWF, particularly the high-molecular-weight

chapterfive70

Figure 1. Early cognitive decline is associated with von Willebrand Factor activity in off-pump coronary artery

bypasssurgery

VWF:Rcof,vonWillebrandFactorr istocetincofactoractivity,correctedforVWFantigen.

#p=0.025betweengroups

multimers from storage pools such as endothelial Weibel-Palade bodies and platelet α-

granules.2,19Furthermore,stimulatedreleaseofVWFfromstoragepoolscanbeinducedwith

thrombin,histamine,f ibrinandcomplementactivation.1IntheCPBgroup,VWFactivitydid

not change signif icantly. Since we corrected both VWF: Rcof and VWF:CB for VWF:Ag, this

couldnotbeattributedtoadilutionaleffect.Asthesurgicaltraumaisatleastcomparableto

theoff-pumpgroup,anothermechanismmustberesponsibleforabolishingthestimulating

effectonVWFactivity.Apossibleexplanationisshearstress-inducedproteolysisofVWFdue

totheuseoftheCPBsystem.Aconstantcardiopulmonarybypassflowrateof2.4L/min⋅m2

(bodysurfacearea)passesthroughtheoxygenatoranda24Frenchaorticcannula(internal

diameter8.0mmandalengthof24cm).Shearstressesintheoxygenatorvariedbetween

25and125dynes/cm2duringanaveragecardiopulmonarybypasstimeof71±28minutes

inourpatients,whilethemaximumshearstressovertheaorticcannulacanvarybetween

375and750dynes/cm2.20,21Highshearforcescaninducestructuralchangesintheshapeof

theVWFmolecule,makingitmoresensitiveforADAMTS-13.4,5Thisleadstotheproteolysisof

thehighest–molecular-weightmultimers,whicharethemosteffectiveinplatelet-mediated

hemostasisunderconditionsofhighshearstress.

Platelet counts signif icantly dropped in both groups after surgery and more pronounced

in the CPB group. However, after correction for hemodilution using hematocrit levels,

postoperativeplateletcountswerecomparabletopreoperativevaluesinbothgroups.An

increaseinplateletnumberistobeexpectedduringsurgery.Recruitmentofplateletsdue

to the surgical trauma may have masked the fact that platelets are still being consumed.

Plateletrecruitmentmayalsoexplainwhycorrectionforhemodilutioncompletelyabolished

thedifferencebetweenpre-andpostoperativeplateletcountsintheCPBgroup.Dropsin

platelet count as a result of other effects of CPB such as damage in cardiotomy suction

systems and membrane oxygenators may thus have been concealed.22,23 In addition, we

could still demonstrate a difference in platelet counts in the later postoperative period

between the two types of surgery (p=0.03), indicating platelet consumption in the off-

pumpgroup.Onthef irstpostoperativeday,plateletcountsweresignif icantlylowerthan

beforesurgery in theoff-pumpgroup,whileplateletcounts in theCPBgroupreturnedto

preoperativevalues.

Patients in the off-pump group demonstrated an increased VWF-activity, which may

have been the result of a reduced VWF-cleaving activity. However, after correction for

hemodilution,ADAMTS-13activity,asmeasuredbythecleavageofshortsyntheticVWFA2-

peptide,wasincreasedintheoff-pumpgroup.ThisincreaseinADAMTS-13activitycanbe

explainedby the releaseofADAMTS-13byhepaticstellatecellsandtoa lesserextentby

endothelialcellsandplateletstocounterbalancethereleaseofVWF:Ag.24-26Nevertheless,

in the present study, the postoperative increase in ADAMTS-13 activity was lower than

the increase in VWF:Ag levels. This disbalance may have contributed to the increased

postoperativeVWFactivityafteroff-pumpsurgery,yetthereisnocurrentclinicalevidence

tosupportthishypothesis.Furthermore,postoperativeVWF:AgandVWFpropeptidelevels

were comparable in both groups, but ADAMTS-13 activity had a tendency to relatively

decreasemoreafterCABGwithCPB.Wehypothesizethatthisiscausedbyconsumptionafter

activationandthattheCPB-inducedstructuralchangesoftheVWFmoleculescouldplaya

roleinthisprocess.Ourresultsareincontrasttothef indingsofMannuccietal.whostudied

ADAMTS-13activityin20on-pumpand13off-pumppatientsinanon-randomizedfashion.

They found a signif icant absolute decrease of ADAMTS-13 activity after both procedures,

whereasVWF:AgandVWF:CBwerebothincreased.27Whetherthisisduetodifferentwaysof

measuringproteaseactivityremainsunclear.28Furtherstudiesareneededtodeterminethe

preciseroleofADAMTS-13incardiacsurgery.

In earlier studies, the role of VWF in CABG with CPB has been studied extensively, in

particularinrelationshiptopostoperativebleeding.29-31However,inallthesestudies,VWF

activity is only studied in on-pump patients, mostly indicating that activity increased

after theprocedure.By lackofacontrolgroup, like theoff-pumppatients in thepresent

study,nodiscriminationcouldbemadebetweeneffectsofthesurgicaltraumaandtheCPB

systemitself.Thepresentstudyisthef irstrandomizedtrialtoourknowledgewhocompares

both VWF:Rcof and VWF:CB levels in on-pump and off-pump patients. The release of VWF,

particularly the high-molecular-weight multimers, due to the surgical trauma can hereby

bediscriminatedfromtheshearstress-inducedproteolysisofVWFduetotheuseoftheCPB


chapterfive72

system. Our results are in accordance with the f indings of Perutelli, who demonstrated a

limitedproteolysisofVWFinthecourseofaCPBsystem,asshownbyprogressivechangesof

multimericstructureandsubunitcomposition.32

MultiplestudieshaveexaminedtheroleofplateletsinCABGwithCPB.Bothpostoperative

thrombocytopeniaandplateletdysfunctionarewell-recognizedsideeffectsofCPBandhave

beenrelatedtobleedingcomplications.7,8,33,34However,theroleofCPB-relatedthrombosis

forwhichplateletshavebeenimplicatedislessclear.Manganoetal.demonstratedthatuse

ofaspirininitiatedwithin48hoursafterCABGsurgeryisassociatedwithareducedincidence

of postoperative ischaemic complications (in heart, brain, kidney, and intestines).35 In

addition, increasing the number of platelets by transfusion was associated with similar

dysfunctionofall fourorgans,anddysfunctionwasmitigatednearlyuniformly inall four

organsbyaspirintherapy.Theresultsofthisstudyareremarkableasmostclinicianshave

beenmoreconcernedaboutthepostoperativebleedingtendency.Therefore,antiplatelet

therapyhasnotbeenconsideredforuseinsurgicalpatients,exceptintheimprovementof

latevein-graftpatency.36

Withthisstudy,wehavealsodemonstratedapossiblebeneficiaryeffectoftheCPBsystem.

Activationofhemostasisandthehypercoagulablestateaftermajorsurgeryarewell-known

phenomenona and may contribute in haemorrhagic and thrombotic events.19,37-39 In an

earlier study, we demonstrated that postoperative D-dimer levels (during the f irst hours

after the operation) are independently associated with cognitive decline on day 4 after

off-pump surgery.18 In the present study with a small subgroup of 30 off-pump patients,

we showed that postoperative VWF:Rcof and D-dimer levels correlated signif icantly.

In addition, in off-pump patients with early postoperative cognitive decline, pre- and

postoperative VWF:Rcof were signif icantly higher than patients with no decline. It is

possible that higher pre- and postoperative VWF activity levels may reflect the presence

of underlying vascular or non-vascular processes that predispose patients to cognitive

declineaftermajorsurgery.However,ourf indingsmayalsofurthersupportthehypothesis

thatearlypostoperativeactivationofhemostasismayplayaroleintheaetiologyofperi-

operative ischaemic complications. Bottiger et al. recently demonstrated an association

betweenearlypostoperativecoagulationactivationandperioperativemyocardialischemia

in patients undergoing vascular surgery.40 As mentioned earlier, Mangano et al. showed

thattheuseofaspirininitiatedwithin48hoursCABGsurgeryisassociatedwithareduced

incidence of postoperative ischaemic complications.35 Therapies promoting coagulation,

such as transfusion of coagulation factors and medication promoting thrombosis e.g.

antif ibrinolyticagentswerealsoassociatedwithanincreasedriskofpostoperativeorgan

failure. It was suggested that inhibition of the procoagulatory response and platelet

activation caused by the surgical stimulus, may prevent adherence to disrupted vascular

endothelium,intravascularthrombosisandsubsequentorganischaemia.Whetheractivation


of hemostasis is definitively a causal pathophysiological factor in the aetiology of peri-

operativeischaemiccomplicationsremainstobedetermined.

Limitations of the study Although patients were randomized in this study, it has several limitations. First, the

numberofpatientsisrathersmall,sothatassociationswithclinicaloutcomearediff icult

todemonstrate.Secondly,wedidnotperformVWFmultimeranalysiswhichmayimpedethe

interpretationoftheVWFdataobservedinthisstudy.Thirdly,theOctopusstudycompared

off-pumpsurgerywithconventionalCABGbothperformedaswhatwasconsideredcommon

practice in our institution at that time. This included other factors associated with the

on-pumpsurgerysuchastheuseofdexamethasonewhichmayhaveaffectedVWFrelease.

However,inarecenttrial,administrationofdexamethasonebeforecardiopulmonarybypass

forpaediatriccardiacsurgerydidnotaffecttheimmediatefeaturesaftersurgeryorchanges

inVWFantigenlevels.41

ConCLuSIonS

VWF activity is increased after off-pump CABG, but not after CABG with cardiopulmonary

bypass.ThesurgicaltraumaisresponsibleforthereleaseofVWF,particularlythehigh-mo-

lecular-weightmultimersfromstoragepools,buttheeffectonVWFhomeostasisiscounter-

actedbyshearstress-inducedproteolysisofVWFinthebypassgroup.

ACKnoWLedGMentS

ThisstudyisasubstudyoftheOctopus-trialthatwasfundedbygrantOG98-026fromthe

NetherlandsNationalHealthInsuranceCouncil.Additionalfundingforlaboratoryresearch

wasprovidedbyMedtronicInc.


references

1.SadlerJE.BiochemistryandgeneticsofvonWillebrandfactor.AnnuRevBiochem1998;67:395-424.:395-424.

2. Moake JL, Turner NA, Stathopoulos NA, Nolasco LH, Hellums JD. Involvement of large plasma vonWillebrandfactor(vWF)multimersandunusuallylargevWFformsderivedfromendothelialcellsinshearstress-inducedplateletaggregation.JClinInvest1986;78(6):1456-1461.

3. Tsai HM, Nagel RL, Hatcher VB, Sussman II. Multimeric composition of endothelial cell-derived vonWillebrandfactor.Blood1989;73(8):2074-2076.

4. Siedlecki CA, Lestini BJ, Kottke-Marchant KK, Eppell SJ, Wilson DL, Marchant RE. Shear-dependentchanges in the three-dimensional structure of human von Willebrand factor. Blood 1996; 88(8):2939-2950.

5.TsaiHM,SussmanII,NagelRL.ShearstressenhancestheproteolysisofvonWillebrandfactorinnormalplasma.Blood1994;83(8):2171-2179.

6.VincentelliA,SusenS,LeTourneauT,SixI,FabreO,JuthierFetal.AcquiredvonWillebrandsyndromeinaorticstenosis.NEnglJMed2003;349(4):343-349.

7.RinderCS,BohnertJ,RinderHM,MitchellJ,AultK,HillmanR.Plateletactivationandaggregationduringcardiopulmonarybypass.Anesthesiology1991;75(3):388-393.

8.HollowayDS,SummariaL,SandesaraJ,VagherJP,AlexanderJC,CapriniJA.Decreasedplateletnumberandfunctionandincreasedfibrinolysiscontributetopostoperativebleedingincardiopulmonarybypasspatients.ThrombHaemost1988;59(1):62-67.

9.GelbAB,RothRI,LevinJ,LondonMJ,NoallRA,HauckWWetal.Changesinbloodcoagulationduringandfollowingcardiopulmonarybypass:lackofcorrelationwithclinicalbleeding.AmJClinPathol1996;106(1):87-99.

10.vanDijkD,NierichAP,JansenEW,NathoeHM,SuykerWJ,DiephuisJCetal.Earlyoutcomeafteroff-pumpversuson-pumpcoronarybypasssurgery:resultsfromarandomizedstudy.Circulation2001;104(15):1761-1766.

11.vanDijkD,JansenEW,HijmanR,NierichAP,DiephuisJC,MoonsKGetal.Cognitiveoutcomeafteroff-pumpandon-pumpcoronaryarterybypassgraftsurgery:arandomizedtrial.JAMA2002;287(11):1405-1412.

12.NathoeHM,vanDijkD,JansenEW,SuykerWJ,DiephuisJC,vanBovenWJetal.Acomparisonofon-pumpandoff-pumpcoronarybypasssurgeryinlow-riskpatients.NEnglJMed2003;348(5):394-402.

13.MurdockPJ,WoodhamsBJ,MatthewsKB,PasiKJ,GoodallAH.vonWillebrandfactoractivitydetectedinamonoclonalantibody-basedELISA:analternativetotheristocetincofactorplateletagglutinationassayfordiagnosticuse.ThrombHaemost1997;78(4):1272-1277.

References 75

14.BorchielliniA,FijnvandraatK,tenCateJW,PajkrtD,vanDeventerSJ,PasterkampGetal.Quantitativeanalysis of von Willebrand factor propeptide release in vivo: effect of experimental endotoxemia andadministrationof1-deamino-8-D-argininevasopressininhumans.Blood1996;88(8):2951-2958.

15.vanderPlasRM,GomesL,MarquartJA,VinkT,MeijersJC,deGrootPGetal.BindingofvonWillebrandfactorto collagen type III: role of specific amino acids in the collagen binding domain of vWF and effects ofneighboringdomains.ThrombHaemost2000;84(6):1005-1011.

16.MoakeJL,WeinsteinMJ,TrollJH,ChuteLE,ColanninoNM.DirectradioimmunedetectioninhumanplasmaoftheassociationbetweenfactorVIIIprocoagulantproteinandvonWillebrandfactor,andtheinteractionofvonWillebrandfactor-boundprocoagulantVIIIwithplatelets.Blood1983;61(6):1163-1173.

17. Kokame K, Nobe Y, Kokubo Y, Okayama A, Miyata T. FRETS-VWF73, a first fluorogenic substrate forADAMTS13assay.BrJHaematol2005;129(1):93-100.

18.vLoB,FijnheerR,NierichAP,KalkmanCJ,vanDijkD.Activationofhemostasisisassociatedwithearlycognitivedeclineafteroff-pumpcoronaryarterybypasssurgery.JThrombHaemost2005;3(9):2114-2117.

19. Mariani MA, Gu YJ, Boonstra PW, Grandjean JG, van Oeveren W, Ebels T. Procoagulant activity afteroff-pumpcoronaryoperation:isthecurrentanticoagulationadequate?AnnThoracSurg1999;67(5):1370-1375.

20.DeSomerF,TaeymansY,DeWachterD,VerdonckP,VanNootenG.Predictionoftheclinicalperformanceofadultarterialcannulas.ArtifOrgans2004;28(7):655-659.

21.DeSomerD,FoubertL,VanackereM,DujardinD,DelangheJ,VanNootenG.Impactofoxygenatordesignon hemolysis, shear stress, and white blood cell and platelet counts. J Cardiothorac Vasc Anesth 1996;10(7):884-889.

22.MuellerXM,TevaearaiHT,HorisbergerJ,AugstburgerM,BooneY,vonSegesserLK.Smartsuctiondeviceforlessbloodtrauma:acomparisonwithCellSaver.EurJCardiothoracSurg2001;19(4):507-511.

23.PalanzoDA,ZarroDL,ManleyNJ,MontesanoRM,QuinnM,GustafsonPA.Effectofsurfacecoatingonplateletcountdropduringcardiopulmonarybypass.Perfusion1999;14(3):195-200.

24. Uemura M, Tatsumi K, Matsumoto M, Fujimoto M, Matsuyama T, Ishikawa M et al. Localization ofADAMTS13tothestellatecellsofhumanliver.Blood2005;106(3):922-924.

25.TurnerN,NolascoL,TaoZ,DongJF,MoakeJ.HumanendothelialcellssynthesizeandreleaseADAMTS-13.JThrombHaemost2006;4(6):1396-1404.

26. Liu L, Choi H, Bernardo A, Bergeron AL, Nolasco L, Ruan C et al. Platelet-derived VWF-cleavingmetalloproteaseADAMTS-13.JThrombHaemost2005;3(11):2536-2544.

27.MannucciPM,ParolariA,CancianiMT,AlemanniF,CameraM.OppositechangesofADAMTS-13andvonWillebrandfactoraftercardiacsurgery.JThrombHaemost2005;3(2):397-399.


28.KremerHovingaJA,MottiniM,LammLeB.MeasurementofADAMTS-13activityinplasmabytheFRETS-VWF73assay:comparisonwithotherassaymethods.JThrombHaemost2006;4(5):1146-1148.

29.PerrinEJ,RayMJ,HawsonGA.TheroleofvonWillebrandfactorinhaemostasisandbloodlossduringandaftercardiopulmonarybypasssurgery.BloodCoagulFibrinolysis1995;6(7):650-658.

30.WeinsteinM,WareJA,TrollJ,SalzmanE.ChangesinvonWillebrandfactorduringcardiacsurgery:effectofdesmopressinacetate.Blood1988;71(6):1648-1655.

31.HackmannT,GascoyneRD,NaimanSC,GroweGH,BurchillLD,JamiesonWRetal.Atrialofdesmopressin(1-desamino-8-D-argininevasopressin)toreducebloodlossinuncomplicatedcardiacsurgery.NEnglJMed1989;321(21):1437-1443.

32.PerutelliP.ProteolysisofvonWillebrandfactorisincreasedduringcardiopulmonarybypass.ThrombRes2001;102(5):467-473.

33.WeerasingheA,TaylorKM.Theplateletincardiopulmonarybypass.AnnThoracSurg1998;66(6):2145-2152.

34.KestinAS,ValeriCR,KhuriSF,LoscalzoJ,EllisPA,MacGregorHetal.Theplateletfunctiondefectofcardiopulmonarybypass.Blood1993;82(1):107-117.

35.ManganoDT.Aspirinandmortality fromcoronarybypasssurgery.NEnglJMed2002;347(17):1309-1317.

36.ChesebroJH,FusterV,ElvebackLR,ClementsIP,SmithHC,HolmesDR,Jr.etal.Effectofdipyridamoleandaspirinonlatevein-graftpatencyaftercoronarybypassoperations.NEnglJMed1984;310(4):209-214.

37.ObaJ,ShiiyaN,MatsuiY,GodaT,SakumaM,YasudaK.Alterationsincoagulationandfibrinolysisaftersurgeryforaorticaneurysm.SurgToday1995;25(6):532-535.

38. Samama CM, Thiry D, Elalamy I, Diaby M, Guillosson JJ, Kieffer E et al. Perioperative activation ofhemostasisinvascularsurgerypatients.Anesthesiology2001;94(1):74-78.

39.LoB,FijnheerR,CastigliegoD,BorstC,KalkmanCJ,NierichAP.Activationofhemostasisaftercoronaryarterybypassgraftingwithorwithoutcardiopulmonarybypass.AnesthAnalg2004;99(3):634-640.

40.BottigerBW,Snyder-RamosSA,LappW,MotschJ,AulmannM,SchweizerMetal.Associationbetweenearlypostoperativecoagulationactivationandperi-operativemyocardialischaemiainpatientsundergoingvascularsurgery.Anaesthesia2005;60(12):1162-1167.

41.LindbergL,ForsellC,JogiP,OlssonAK.Effectsofdexamethasoneonclinicalcourse,C-reactiveprotein,S100B protein and von Willebrand factor antigen after paediatric cardiac surgery. Br J Anaesth 2003;90(6):728-732.

References 77

Chapter six

Local anesthetic actions on thromboxane-induced platelet aggregation

6

Bernard Lo, Md1, Christian W. Hönemann, Md2, rainer Kohrs, Md1,

Markus W. Hollmann, Md3, renate K. Polanowska-Grabowska, Phd4,

Adrian r. L. Gear, Phd4, and Marcel e. durieux, Md Phd1,5

UniversityofVirginiaHealthSystem,DepartmentsofAnesthesiology1and

Biochemistry&MolecularGenetics4,Charlottesville,Virginia;Departmentof

Anesthesiology5,UniversityHospitalMaastricht,TheNetherlands;Depart-

mentofAnesthesiology3,UniversityofHeidelberg,Germany;andKlinikund

PoliklinikfürAnästhesiologieundOperativeIntensivmedizin2,Universitäts-

klinikumMünster,Germany

AnesthAnalg2001Nov;93(5):1240-5

chaptersix80

ABStrACt

Some local anesthetics (LA), in concentrations present in blood during IV or epidural

infusion,inhibitthrombusformationinthepostoperativeperiod.Studiesonthromboxane

A2 (TXA2) signaling in a recombinant model suggest that interference with TXA2-induced

plateletaggregationmayexplain,inpart,theantithromboticactionsofepiduralanalgesia

andIVLAinfusion.InthisstudyweinvestigatedtheeffectsofclinicallyusedLAs(lidocaine,

ropivacaine,andbupivacaine)onTXA2-inducedearlyplateletaggregation(1–5s)byusing

quenched-flow and optical aggregometry. Our f indings demonstrate that the LAs tested

seemtohaveonlyalimitedabilitytoinhibitTXA2-inducedplateletaggregationassessedat

earlytimes(1–5s).Therefore,theclinicaleffectsofLAsonthrombiformationareunlikely

tobeexplainedby thismanneralone.At largeLAconcentrations,moderateeffectswere

obtained. Prolonged incubation with LA did not signif icantly increase effectiveness,

and the lack of an effect could not be explained by generation of secondary mediators.

Theresultswereindependentoftheanestheticstudied.LocalanestheticeffectsonTXA2-

inducedearlyplateletaggregation(1–5s)areunlikelytoplayamajorroleintheclinically

observedantithromboticeffectsoflocalanesthetics.

Localanestheticactionsonthromboxane-inducedplateletaggregation 81

IntroduCtIon

The trauma of surgery induces a systemic inflammatory response and an associated

hypercoagulable state. The magnitude of both is related to the traumatic insult. After

surgery with signif icant tissue trauma, the combination of this state with postoperative

immobilization leads to a frequent incidence of postoperative deep venous thrombosis

(PODVT). Although anticoagulants (such as low-molecular-weight heparin) can prevent

PODVTeffectively,thesecompoundsarenotwithoutriskinthepostoperativepatient,and

therapiesthatwouldpreventthehypercoagulablestatewouldbepreferred.However,the

mechanisms underlying the hypercoagulable state are still unclear. Several inflammatory

mediators are also potent platelet aggregators, and increased blood levels of such

compounds have been determined after surgery. Thromboxane A2 (TXA2) is one of these

compounds, and its levels are increased after various types of surgery, such as invasive

orthopedic,cardiac,abdominal,vascular,orobstetricsurgery.1-5Inaddition,TXA2hasbeen

proposed as a mediator of myocardial ischemia and coronary vasoconstriction, as well as

thrombosis.6-8

Theuseofepiduralanalgesiaisassociatedwithasignif icantreductionintheincidenceof

PODVTandpulmonaryemboli,andsimilarreductionsareobtainedwhenlocalanesthetics

(LAs) are infused IV.9-12 We have shown previously that LAs, in concentrations as present

inbloodduringIVorepidural infusion(1–10μM), inhibitTXA2signaling inarecombinant

model.13 We hypothesized that LA interference with TXA2-induced platelet aggregation

mayexplain,inpart,theantithromboticactionsofepiduralanalgesiaandIVLAinfusion.

Therefore,westudiedtheeffectsofseveralLAsonTXA2-inducedplateletaggregationinan

invitromodel.

chaptersix82

MetHodS

ThestudyprotocolwasapprovedbytheUniversityofVirginiaIRB.Venousbloodwasobtained

byantecubitalvenipuncturefrom10nonsmokingvolunteerswhohadnotingestedafatty

mealfor6–8hbeforeblooddonationoranydrugswithin10days.Theanticoagulantacid

citratedextrose(ACD)(6.6mMglucose,115mMtrisodiumcitrate,and10mMcitricacid)

wasaddedina10:1(vol/vol)ratio(apparentcitrateconcentration11.5mM).Platelet-rich

plasma(PRP)waspreparedbyslow-speedcentrifugation(2x3minand1x5minat350g)

(14).ToinhibitendogenousTXA2production,indomethacin(1μg/mL)wasadded.PRPwas

preparedinplastictubes,whichwerecappedinanatmosphereof5%CO2and95%airtohelp

preservepHandplateletquality.ThePRPwasstoredatroomtemperatureuntiluse(within

4hunlessindicatedotherwise).

Figure1Ashowsthebasicprincipleofthemethod.14PRPisplacedinoneplasticsyringeand

theagonist(inthiscase,themetabolicallystableTXA2analogU-46619)inanothersyringe.

A dual-drive syringe pump forces these solutions through 0.8-mm inner diameter Teflon

tubingbeforeenteringacommonreactiontubeof0.25mminnerdiameter,whichmimics

shear stress forces found in the arterial circulation (10–50 dynes/cm2). Reaction time is

determinedbytubinglengthandpumprate,andthereactionisstoppedbyquenchingwith

glutaraldehyde. Single platelet counts are then evaluated in the effluent by a resistive

particlecounter.

LAsweredilutedinTyrode’ssolution(inmM:150NaCl,5KCl,1MgCl2,16H2O,2CaCl2/H2O,10

dextrose,10HEPES)andaddedtothePRPattheappropriateconcentrationandincubated

for10min(37°C),unlessotherwiseindicated.ThesameamountofTyrode’ssolutionwithout

anestheticwasaddedtoacontrolsample.Experimentswereperformedat37°C.Quenched-

flow aggregometry was used for the majority of experiments, because it detects early

platelet aggregation events (<5 s) and mimics conditions in the microcirculation better

thanopticalaggregometry.14

Optical aggregometry is a widely used method whereby light transmission through PRP is

continuouslyrecorded.Theaggregometer(Lumiaggregometer;ChronologCorp.,Havertown,

PA)usedastirringrateof1000rpmat37°C.Eachaliquotcontained400μLoftheplatelet

suspensionwithapproximately4x105plateletspermicroliter.Baselinewasmonitoredfor

1–5mintoensurethatbaselinewasstable.Afteraddingtheaggregation-inducingreagent

(U-46619; 1 μM), light transmission increased progressively as aggregation began and

reachedaplateauwhenaggregationwasmaximal.Maximumaggregationoccurredwithin

2–3 min. The magnitude of aggregation was assessed by measuring the maximum rate of

aggregation (the tangent to the curve measure in millimeters per unit time, reported as


slope value). Mean values of samples of control PRP (with buffer solution Tyrode) were

comparedwiththoseincubatedfor30,60,and120mininTyrode’ssolutioncontaining1,10,

or100μMbupivacaine.Plateletcountwasthesameforcontrolandthetreatmentgroups.

U-46619wasobtainedfromCaymanChemical(AnnArbor,MI).Ropivacainewasakindgift

from Astra Pharmaceuticals, L.P. (Westborough, MA), and other chemicals were obtained

fromSigma(St.Louis,MO).

20

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1µM U-466195µM ADP

1µM U-46619

1µM U-46619

Glutaraldehyde

1µM U-46619+

10µM SQ29548

Platelet Rich Plasma

single plateletcounting

Reaction tube

Figure 1. (A)Schematicofthequenched-flowsystemtostudyplateletaggregation.(B)Concentration-responsecurvesforU-46619

(1μM)-inducedplateletaggregationafter2,3,4,and5s.Themostef fectiveaggregationwasobtainedafter5s.Thehalf-maximal

ef fectconcentrationforthelongesttimepoint(5s)was8.7±3.9x10-7M.(C)U-46619(1μM)-inducedplateletaggregationwasnearly

completelyprevented(96%±4%ofcontrol)bySQ29548(10μM,P<0.05, t-test),aTXA2antagonist. (D)U-46619-inducedplatelet

aggregationwasfoundtobeapproximatelyf ivefoldmorepotentthanadenosinediphosphate(ADP).U-46619(1μM)reducedsingle

plateletcountto37%±8%ofcontrol;ADP(5μM)reduceditto41%±6%(n=3,P<0.05at2and3s,t-test).

chaptersix84

Resultsarereportedasmean±SEM(n=7,unlessotherwisestated).Statisticaltestsused

areindicatedinResults.P<0.05wasconsideredsignif icant.Concentration-responsecurves

weref ittothefollowinglogisticfunction,derivedfromtheHillequation:y=ymin+(ymax-

ymin)[1-xn/(x50n+xn)],whereymaxandyminarethemaximumandminimumresponseobtained,

nistheHillcoeff icient,andx50isthehalf-maximaleffectconcentration(EC50foragonist)

orhalf-inhibitoryeffectconcentration(IC50forantagonist).

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10 µM bupivacaine100 µM bupivacaine1 mM bupivacaine

1 µM U-46619100 µM Lidocaine

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1µM U-46619Tyrode’s

1µM U-4661910 µM ropivacaine

A

C D

B

Figure 2. (A)Tyrode’ssolutiondidnotinduceplateletaggregation.(B–D)AllthreelocalanestheticsinhibitedU-46619(1μM)-induced

plateletaggregationinaconcentration-dependentmanner.Lidocaine(B)inhibitedplateletaggregationat10-1(P<0.05at2,3,4,

and5s,t-test)and10-2Mandropivacaine(C)at10-3(P<0.05at3and4s,t-test)and10-4M,whereasbupivacaine(D)wasmorepotent

thenthetwootherlocalanesthetics,inhibitingplateletaggregationatconcentrationsof10-3(P<0.05at2,3,4,and5s,t-test),10-4

(P<0.05at3,4,and5s,t-test),and10-5M.

reSuLtS

U-46619 effectively aggregated platelets as determined by single-particle counting and

quenched-flow aggregometry (Fig. 1D). To assess the best time to study aggregation,

concentration-response relationships were determined after 2-, 3-, 4-, and 5-s reaction

times (Table 1, Fig. 1B). The reaction was very fast, because no appreciable differences

in the concentration-response relationship were noted when reaction time was varied

between2and5s.TheEC50determinedfromthelongesttimepoint(5s)was8.7±3.9x10-7

M(Table1).Onthebasisoftheseexperiments,weselectedaU-46619concentrationof1

μM and a reaction duration of 5 s for subsequent studies. U-46619 (1 μM) reduced single

plateletcountto34%±7%ofcontrol.Thiseffectwasinhibitednearlycompletely(96%±

5%ofcontrol,Fig.1C)bytheTXA2-antagonistSQ29549, indicatingthattheresponsewas

indeedcausedbyTXA2signaling.

WecomparedtheeffectivenessofU-46619(1μM)withtheaggregatingeffectofadenosine

diphosphate(ADP)(5μM),anagonistfrequentlyusedforplateletaggregationstudies.We

foundU-46619tobeapproximatelyf ivefoldmorepotentthanADP(Fig.1D).U-46619(1μM)

reducedsingleplateletcountto37%±8%ofcontrol;ADP(5μM)reduceditto41%±6%(n

=3).

AfterconfirmingthatTyrode’ssolutiondidnotinduceplateletaggregationbyitself(Fig.2A),

wetestedtheeffectsof lidocaine,bupivacaine,andropivacaineonplateletaggregation.

AllthreeanestheticsinhibitedU-46619-inducedplateletaggregationinaconcentration-

dependent manner. However, the concentrations required were 5- to 10-fold higher than

thosefoundtoinhibitTXA2signalinginourpreviousstudy(Fig.2B–D).13

table 1. Fitting Values for u-466619-Induced Platelet Aggregation

Variable 2 s 3 s 4 s 5 s

Hillcoeff icient 0.28±0.165 0.37±0.07 0.66±0.08 0.64±0.16

EC50(10-6M) 7.5±8.5 2.55±1.08 1.9±0.38 0.87±0.39

Emax(%ofcontrol) 106±16 103±6 91±2 93±6

Thetableshowsmean±SEMforf ittingvariablesderivedfromtheHillequationforU-46619

(1μM)-inducedplateletaggregationinthequenched-flowmodelafterdif ferenttimepoints.

EC50=half-maximalef fectconcentration;Emax=calculatedmaximalef fect.


86

We have shown previously that prolonged exposure of TXA2 receptors to LAs increases

sensitivitytothecompounds.15Becauseprolongedexposuremightalsomimictheclinical

situationofepiduralanalgesiamoreclosely,westudiedtheeffectof4hincubationin1μM

bupivacaineorin1μMropivacaineonTXA2-inducedplateletaggregation;theeffectofboth

compoundswasnottimedependent(Fig.3,AandB).

Platelet aggregation can be associated with the release of intracellular platelet granule

contents(containingADP,serotonin,nitricoxide,andotherfactors),andthismayamplify

platelet aggregation.16 If so, even signif icant inhibition by LAs of TXA2 signaling might

have littleeffectonaggregation,becausetheeffectmaybeoverwhelmedbysubsequent

secondarymediatorrelease.Totestthishypothesis,weinvestigatedhowmuchoftheeffect

ofU-46619iscausedbysecondarymediatorrelease.Weincubatedplateletsfor10minin1

μMU-46619andthenremovedplateletsbycentrifugation.Thesupernatant(whichwould

containsecretedmediators),mixedwithexcessSQ29549toblockanyeffectofremaining

U-46619, was then used as agonist for a subsequent aggregation study. The supernatant

hadlittleaggregatingability(Fig.4A).Thus,inducedreleaseofsecondarymediatorsdoes

notplayanimportantrole inthisaggregationmodel,andthelackofLAeffectcannotbe

explainedonthebasisofmassivereleaseofsecondarymediators.

Finally, the duration of agonist exposure in quenched flow aggregometry (5 s) was much

shorter than that in our previous study (1 min). Although we demonstrated (as shown

previously)thattheeffectofU-46619wasveryrapid,itisconceivablethatthedifference

inexposuretimemightinfluencetheresult.Therefore,wedeterminedtheeffectofthree

different concentrations of bupivacaine (1, 10, and 100 μM) on U-46619 (1 μM)-induced

platelet aggregation in an optical aggregometer, where platelets can be exposed to

agonist for minutes. The results were very similar to those obtained with quenched-flow

aggregometry: only bupivacaine concentrations 100 μM and incubation times 60 min

signif icantly(P<0.05,one-wayanalysisofvariancewithBonferroni’scorrection)reduced

theU-46619-inducedincreaseinlighttransmissioncorrespondingtoanimpairedplatelet

aggregation (Fig. 4 B, Table 2). Therefore, concentrations of bupivacaine that produced

TXA2signalingblockadeinourpreviousstudydidnotinducesignif icantinhibitionofearly

plateletaggregationinthismodel.13

chaptersix

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let

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60 120 180 240time (s)

1µM U-466191µM S(-)ropivacaine

A

B

Figure 3. (AandB) Theeffectof4hincubationin1μMbupivacaine(A)orropivacaine(B)on1μMU-46619-inducedplateletaggrega-

tion. The effect of the compounds was not signif icantly time dependent: even after 4 h incubation, only minor ef fects on platelet

aggregationwereobserved.


88

1 2 3 4 5time (s)

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A

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Figure4.Theeffectofsupernatant(preparationasdescribedinResults)whenusedasanagonistforsubsequentaggregation.The

supernatanthadonlyminoraggregatingability:itinduceda15%–20%decreaseinsingleplateletcount.(B)Theeffectofthree

dif ferentconcentrationsofbupivacaine(1,10,and100μM)onU-46619(1μM)-inducedplateletaggregationwithtransmissionag-

gregometry.Onlybupivacaineconcentrations ≥100μMandincubationtimes ≥60minsignif icantlyreducedtheU-46619-induced

increaseinlighttransmissioncorrespondingtoanimpairedplateletaggregation.

table 2. the effects of Bupivacaine on u-46619-Induced Platelet Aggregation using transmission Aggregometry

Variable 30 min 60 min 120 min

Control 27±1 24±2 20±2

Bupivacaine1μM 28±1 22.8±1.39 19±3

Bupivacaine10μM 29±2 22±3 21±1

Bupivacaine100μM 24±2 12±1* 10±1*

Thetableshowsmean±semfortheincreaseinlighttransmission,shownastheslopeoftheU-46619(1μM)-inducedplateletaggregation

curve. Platelets were incubated for 30, 60, and 120 min in Tyrode’s solution (control) or bupivacaine (1, 10, or 100 μM). Data obtained

afterincubationinbupivacainewerecomparedwiththoseafterincubationinTyrode’ssolutionbyusingone-wayanalysisofvarianceand

Bonferroni’scorrection,ifnecessary.*P<0.05.

chaptersix

89

dISCuSSIon

OurfindingsdemonstratethattheclinicallyusedLAslidocaine,ropivacaine,andbupivacaine

seem to have only a limited ability to inhibit TXA2-induced platelet aggregation assessed

at early times. The results were independent of the anesthetic studied, and even at large

concentrations only modest effects were obtained. Prolonged incubation with the LA did

not increase effectiveness, and the lack of effect could not be explained by generation of

secondary mediators. Similar results were obtained with a different model of aggregation

(opticalaggregometry).Therefore,clinicallyrelevantLAconcentrationsonTXA2-inducedearly

plateletaggregationareunlikelytoplayamajorroleintheclinicallyobservedantithrombotic

effectsofLA.

WestudiedtheeffectsofLAsonTXA2-mediatedplateletaggregationbecauseTXA2hasbeen

implicated in the hypercoagulable state that develops after various types of surgery and

becausewepreviouslyobservedsignificantinhibitionofTXA2receptorfunctionbyclinically

relevantconcentrationsofLAsinseveralcellmodels.13

Thromboembolic complications are common after surgery and seem to result from

hypercoagulationandhypoperfusion(thelatterofteninducedbyvasoconstriction).Aftermajor

orthopedicorurologicsurgery,PODVToccursin30%–80%ofpatients.12,17Similarly,myocardial

ischemiainducedbymicrothrombosis,coronaryvasoconstriction,orbothisfrequent.18,19The

mechanisms for theseadverseeventsarepoorlyunderstood,but inflammatorymediators—

releasedinresponsetosurgicaltraumaandinducingthrombosisandvasoconstriction—are

likely to be pivotal. TXA2 is a potent platelet aggregator and vasoconstrictor. It is one of

the major mediators released during orthopedic, cardiac, abdominal, vascular, or obstetric

surgery.1-5 TXA2 has been proposed as a mediator of myocardial ischemia and coronary

vasoconstriction, as well as thrombosis.6-8 Thus, TXA2 is likely to play an important role in

perioperativethrombosis,andthebeneficialactionsofepiduralandIVLAsonpostoperative

hypercoagulationcouldbeexplainedbyinterferencewithTXA2signaling.10-12,20

WepreviouslyexpressedhumanTXA2receptorsinXenopusoocytesandstudiedLAeffectson

Ca-activatedClcurrentsinducedbyU-46619.13,15Bupivacaine,atmicromolarconcentrations,

blocked TXA2 signaling effectively. Lidocaine was significantly less potent. We obtained

similar results in K562 cells, a human erythroid leukemia tumor line that endogenously

expressesTXA2receptors.13WemeasuredintracellularCareleasebyfluorometryandobserved

inhibitionbybupivacaine,lidocaine,andropivacaine.Becausewefoundsimilareffectsboth

inarecombinantsystemandanativesystem,weproceededwiththisstudyandevaluatedthe

effectsofLAsonTXA2-mediatedplateletaggregation.

Localanestheticactionsonthromboxane-inducedplateletaggregation

90

We chose the quenched-flow model of platelet aggregation for several reasons.14,21 First, it

mimicstheconditionswithinthevasculaturemuchmorecloselythandootheraggregation

systems.Inparticular,shearstressisveryimportantforplateletbehaviorandisusuallyclose

to zero in other platelet aggregation models. In the quenched-flow system, however, it is

maintained at relevant values throughout the activation process.14 Second, quenched-flow

aggregometryallowsonetostudyearlyplateletaggregation(within1–5s),becausereaction

times are precisely controlled. TXA2 is an early activator in aggregation, and we therefore

wishedtodetermineLAeffectsonitsactionduringthefirstseveralsecondsofaggregation.16,22

However,becausesignificanteffectsoftheLAswereobservedatlargeconcentrationsonly,

we repeated some of our experiments in a more conventional transmission aggregometry

systemandobtainedsimilarresults.Theseresultsareincontrasttoearlierstudiesthatused

thromboelastography and activated clotting time.23 In this study, bupivacaine inhibited

plateletaggregationinbothmodelsatclinicallyrelevantconcentrations.Thedifferencein

resultsbetweenourpreviousandpresentstudiesareunlikelytobeexplainedbydifferences

inTXA2receptortypes.DespitethefactthattherecombinantTXA2receptorsusedinXenopus

oocyteswerefromtherat,inallotherinstanceshumanreceptorswereused.However,thereis

onlyasingleTXA2receptorsubtypeinhumans,andthereareonlyminordifferencesbetween

ratandhumanTXA2receptors.

Becauseinallmodelsstudied,LAsandagonistswereappliedtocellsinsolution,itisunlikely

that access to the cells explains the different results. However, in contrast to the oocytes

andK562cells(whichwerestudiedinelectrolytesolutions),plateletswerestudiedinserum.

LA binding to 1-acid glycoprotein may therefore explain part of the different results. This

is particularly true for highly protein-bound compounds such as bupivacaine. Lidocaine is

less protein bound but was also much less potent in our previous studies. Therefore, even

amodestdecrease inavailabilitywouldhavecausedconcentrations required for inhibition

to be outside the range studied. To test this hypothesis, a study of LA effects on platelet

aggregationinasolutionwithknownfreedrugconcentrationswouldberequired.Asecond

potentialexplanationforthedifferenceinresultsisthecomplexityofthepathwaystudied.

InbothoocytesandK562cells,ourendpointwasintracellularCarelease(determinedasCa-

activatedClcurrentinoocytesandfluorescencechangesinK562cells).Thiseventhappens

proximalinthesignalingpathway.Thecellularchangesleadingtoplateletaggregationare

much more complex, and it is conceivable that amplification steps within the aggregation

pathway obscure a modest effect of LAs. To test this hypothesis, the effects of LAs on

intracellularCareleaseinTXA2activatedplateletswillberequired.

chaptersix

91Localanestheticactionsonthromboxane-inducedplateletaggregation

Whateverthemechanism,itseemsunlikelythattheclinicallyobservedantithromboticeffects

ofclinicallyrelevantconcentrationsofLAscanbeexplainedbyinterferencewithTXA2induced

plateletaggregation,andotherpotentialtargetsneedtobeexplored.

ACKnoWLedGMentS

This work was supported by “Ben Covino Award 1998” of the International Anaesthesia

ResearchSocietysponsoredbyAstraPainControl,Inc.(CWH)andinpartbyNationalInstitute

ofHealthGrantGMS52387(MED),Bethesda,MD,andanAmericanHeartAssociationgrant

(Mid-AtlanticAff iliation)VHA9920345U(MWH),Baltimore,MD.Dr.Hönemannissupported

byInnovativeMedizinischeForschungGrantIMFI-6-II/96-8andIMFI-6-II/97-27,Münster,

Germany,andinpartbytheCarmanTrust,RichmondVA(ARLG).Dr.Hollmannissupportedin

partbyagrantoftheGermanResearchSociety(DFGHO2199/1-1),Bonn,Germany.

FootnoteS

Presented in part at the 4th Congress on Eicosanoids and Bioactive Lipids in Cancer,

Inflammation and Radiation Injury, San Diego, CA, 1997 (meeting report published in

AdvancesinMedicineandBiologicalResearch1999;469:269–76)andattheannualmeeting

oftheAmericanSocietyofAnesthesiologistsinOrlando,FL,October,1998.


references

1. Vesterqvist O, Schott U, Berseus O, Axelsson K, Green K. In vivo production of thromboxane andprostacyclininpatientsfollowingtotalhiparthroplasty.ScandJClinLabInvest1988;48:233–9.

2. Teoh KH, Fremes SE, Weisel RD, Christakis GT, Romaschin AD, Harding RS et al. Cardiac release ofprostacyclinandthromboxaneA2duringcoronaryrevascularization.JThoracCardiovascSurg1987;93:120–6.

3.SchillingMK,GassmannN,SigurdssonGH,RegliB,StoupisC,FurrerMetal.RoleofthromboxaneandleukotrieneB4 inpatientswithacute respiratorydistresssyndromeafteroesphagectomy.BrJAnaesth1998;80:36–40.

4.BarryMC,KellyC,BurkeP,SheehanS,RedmondHP,Bouchier-HayesD.Immunologicalandphysiologicalresponsestoaorticsurgery:effectofreperfusiononneutrophilandmonocyteactivationandpulmonaryfunction.BrJSurg1997;84:513–9.

5. Ylikorkala O, Makila UM. Prostacyclin and thromboxane in gynecology and obstetrics. Am J ObstetGynecol1985;152:318–29.

6. Ito BR, Roth DM, Engler RL. Thromboxane A2 and peptidoleukotrienes contribute to the myocardialischemiaandcontractiledysfunctioninresponsetointracoronaryinfusionofcomplementC5ainpigs.CircRes1990;66:596–607.

7. Montalescot G, Drobinski G, Maclouf J, Lellouche F, Ankri A, Moussallem A et al. Early thromboxanerelease during pacing-induced myocardial ischemia with angiographically normal coronary arteries. AmHeartJ1990;120:1445–7.

8.PackhamMA.Roleofplateletsinthrombosisandhemostasis.CanJPhysiolPharmacol1994;72:278–84.

9.ModigJ,BorgT,BaggeL,SaldeenT.Roleofextraduralandofgeneralanaesthesia infibrinolysisandcoagulationaftertotalhipreplacement.BrJAnaesth1983;55:625–9.

10.ModigJ,BorgT,KarlstromG,MaripuuE,SahlstedtB.Thromboembolismaftertotalhipreplacement:roleofepiduralandgeneralanesthesia.AnesthAnalg1983;62:174–80.

11. Rodgers A, Walker N, Schug S, McKee A, Kehlet A, van Zundert H et al. Reduction of postoperativemortality and morbidity with epidural or spinal anesthesia: results from overview of randomized trials.BMJ2000;321:1493–505.

12. Cooke ED, Bowcock SA, Lloyd MJ, Pilcher MF. Intravenous lignocaine in prevention of deep venousthrombosisafterelectivehipsurgery.Lancet1977;2:797–9.

13.HoenemannCW,PodranskiT,LoB,DurieuxME.LocalanestheticeffectsonthromboxaneA2signaling.Anesthesiology1998;89:A886.

References 93

14.GearARL.Rapidreactionsofplateletsstudiedbyaquenched-flowapproach:aggregationkinetics.JLabClinMed1982;100:866–86.

15.HonemannCW,ArledgeJA,PodranskiT,DurieuxME.Stereoselective inhibitionof thromboxaneA(2)receptorfunctioningrecombinantlyexpressedinXenopusoocytes.AnesthAnalg1999;88(Suppl):S346.

16. Packham MA, Kinlough-Rathbone RL, Mustard JF. Thromboxane A2 causes feedback amplificationinvolvingextensivethromboxaneA2formationonclosecontactofhumanplatelets inmediawitha lowconcentrationofionizedcalcium.Blood1987;70:647–51.

17.BradleyJG,KrugenerGH,JagerHJ.Theeffectivenessof intermittentplantarvenouscompression inpreventionofdeepvenousthrombosisaftertotalhiparthroplasty.JArthroplasty1993;8:57–61.

18. Landesberg G, Einav S, Christopherson R, Beattie C, Berlatzky Y, Rosenfeld B et al. Perioperativeischemiaandcardiaccomplicationsinmajorvascularsurgery:importanceofthepreoperativetwelve-leadelectrocardiogram.JVascSurg1997;26:570–8.

19.SpiessBD.Ischemia:acoagulationproblem?JCardiovascPharmacol1996;27(Suppl1):S38–41.

20.OdoomJA,DokterPWC,SturkA,TenCateJW,SihIL,BovillJG.Theinfluenceofepiduralanalgesiaonplatelet function and correlation with plasma bupivacaine concentrations. Eur J Anaesthesiol 1988; 5:305–12.

21.HonemannCW,LoB,EreraJ,Polanowska-GrabowskaR,GearAR,DurieuxME.LocalanestheticeffectsonTXA2receptormediatedplateletaggregationusingquenchedflowaggregometry.AdvMedBiolRes1999;469:269–76.

22. De Clerck FF Janssen PA. Amplificationmechanisms in platelet activation and arterial thrombosis. JHypertensSuppl1990;8:S87–93.

23. Kohrs R, Honemann CW, Feirer N, Durieux ME. Local anesthetics and whole blood coagulation. RegAnesthPainMed1999;24:326–30.

Chapter seven

C-reactive protein is a risk indicator for atrial fibrillation after myocardial revascularization

7

Bernard Lo Md1; rob Fijnheer, Md, Phd2; Arno P. nierich, Md; Phd3;

Peter Bruins, Md, Phd1; Cor J. Kalkman, Md, Phd1

DepartmentofAnesthesiology1,DepartmentofHematology2.

UniversityMedicalCenterUtrecht,Utrecht,TheNetherlands;


IsalaClinics,Zwolle

AnnThoracSurg2005May;79(5):1530-5

chapterseven96

BACKGround

Activation of the complement system after coronary artery bypass graft (CABG) surgery

involves C-reactive protein (CRP). This inflammatory response is related to baseline CRP

levelsandassociatedwithpostoperativearrhythmia,inparticularatrialf ibrillation(AF).

WeinvestigatedwhetherbaselineCRPlevelsareariskindicatorfortheoccurrenceofAFand

whetherthisphenomenoniscardiopulmonarybypass(CPB)-dependent.

MethodsCRPwasmeasuredinperioperativebloodsamplesofpatientsoftheOctopus-study(CABG

surgerywith(n=73)orwithoutCPB(n=79)).BaselineCRPwasdichotomizedintoalowanda

highbaselinegroup,usingacut-offof3.0mg/L.

resultsAfter CABG with CPB 11 of 53 patients (21%) with low preoperative CRP levels developed

AF,versus11of20patients(55%)withhighbaselineCRPlevels(p=0.01).Intheoff-pump

groupAFoccurredin4of52patients(8%)whohadlowbaselineCRPlevels,versusin8of

27patients(30%)withhighpreoperativeCRPlevels(p=0.002).Afteradjustingforage,the

odds ratio [95%-confidence interval] was 4.6 [1.4-15.3] with CPB, 3.7 [0.93-14.7] in the

off-pumpgroupand3.3[1.4-7.6]forbothgroupstogether.ContinuousbaselineCRPwasan

independentpredictorforAFinamultivariatelogisticregressionmodel(p=0.02).

Conclusions PatientswithhighbaselineCRPlevelsareathigherriskofdevelopingpostoperativeAFin

bothon-pumpandoff-pumpsurgery.

C-reactiveproteinisariskindicatorforatrialfibrillationaftermyocardialrevascularization 97

IntroduCtIon

Despite the use of prophylactic anti-arrhythmic medication, atrial f ibrillation (AF) still

occurs in 20% to 40% in patients undergoing coronary artery bypass grafting (CABG).

Increasedriskofstrokeandrenaldysfunction,prolongedhospitalstay,andaccompanying

costs are of major concern.1-2 Although multiple studies have attempted to determine

predictorsfortheoccurrenceofpostoperativeAF,theexactpathogenesisremainsunclear.1-4

InrecentyearsthereisgrowingevidencethatAFisassociatedwithaninflammatorystate,

whichcanbereflectedbyplasmaC-reactiveprotein(CRP)levels.5-8CRPlevelsconstitutean

independentcardiacriskfactorandstudieshaveshownthattheyareelevatedinpatients

withpostoperativeandnon-postoperativeAF.6-9Postsurgeryactivationofthecomplement

systemafterCABGinvolvesCRP.Thisresponseisassociatedwithpostoperativearrhythmia,

andrelatedtobaselineCRPlevels.7ElevatedbaselineCRPlevelsmightrepresentalow-level

preoperativeinflammatorystate,that,whenalteredbythesurgicalprocedure,mayleadto

ahigherincidenceofpostoperativeAF.BaselineCRPlevelsmightthusallowindicationof

patientswithincreasedrisk.

TheassociationbetweenCRPandAFhasonlybeendescribedinon-pumpCABGandnotin

off-pumpsurgery.Therefore,weuseddata fromtheOctopusstudytotestthehypothesis

whetherlevelsofCRPbeforeCABGsurgerywithandwithoutuseofCPBareassociatedwith

theoccurrenceofAF.

chapterseven98

MAterIAL And MetHodS

PatientsBloodsamplesfordeterminationofCRPwerecollectedfromthelastconsecutive152patients

whoparticipatedintheOctopus-study,alargerrandomizedtrialcomparingon-pumpand

off-pumpCABG.10,11Therewasnoadditionalselectioncriteriaentryforthisstudy.Design

andmethodsoftheOctopusmulticentertrialhavebeendescribedindetailelsewhere.10,11

In short, all participants had stable angina pectoris (Braunwald Class I-II, a-c) and were

randomlyallocatedtoundergoCABGwithuseofCPB(CPBgroup;n=73)orwithoutuseof

CPB(off-pump;n=79).Patientswereexcludedincaseofemergencyorconcomitantmajor

surgery, Q-wave myocardial infarction in the previous 6 weeks, or poor left ventricular

function.

All patients gave written informed consent for the study. The study was approved by the

localethicalandresearchcouncil.

treatment and ProceduresThegoalofsurgerywastoobtaincompletearterialrevascularization.Withtheexception

ofemergencyproceduresalloperationswereperformedbycardiacsurgeonsexperiencedin

bothoff-pumpandon-pumpbypasssurgery.Intheon-pumpgroup,patientsreceivedtotal

intravenous anesthesia, including high-dose opioids (sufentanil 2-3 μg/kg at induction,

continuedwith0.5μg/kg.huntiltheendofsurgery),whereasintheoff–pumpgroup75%

ofthepatientsreceivedthoracicepiduralanesthesiacombinedwithlow-doseintravenous

opioids (sufentanil 0.25-0.5 μg/kg at induction). The CPB patients received 1 mg/kg

dexamethasone after induction of anesthesia. Surgical access to the heart was in both

groupsachievedbymidsternalincision.

In the CPB group, the extracorporeal circuit consisted of a membrane oxygenator with

integrated heat exchanger, venous reservoir and polyvinyl tubing system and a non-

pulsatilerollerpump(BaxterHealthcareCorporation,Irvine,CA,USA)andwasprimedwith

crystalloid-colloid mixture. Only the oxygenator and the venous reservoir were heparin

coated.BeforeconnectiontoCPB,porcineheparin(300IU/kg,LeoPharmaceuticalProducts

BV,Weesp,TheNetherlands)wasadministeredinordertoachieveanactivatedcoagulation

time (ACT) > 450 s (Hemochron 400, International Technidyne Corp., NJ, USA). CPB was

managedaccordingtotheα-statprinciple,withaminimalnasopharyngealtemperatureof

32oC,CPBflowratewaskeptat2.4L/min.m2.Myocardialprotectionwasachievedwithcold

(4oC)potassiumcardioplegia(Plegisol,AbbottInc,Chicago,IL,USA).Aftercompletionofall

distalanastomoses,theaorticcross-clampwasremovedandtheproximalanastomoseswere

performedwithapartialoccludingclamp.Meanwhile,thepatientwasrewarmedto37°C.


Heparinwasneutralizedby3mg/kgprotaminechloride(Hoffman/LaRocheB.V,Mijdrecht,

The Netherlands). To reduce blood loss, blood was recollected with a suction cardiotomy

reservoirintheCPB-group,whereasacell-saverwasusedintheoff-pumpgroup.

Intheoff-pumpgroup,aftermediansternotomy,coronarybypassgraftingwasperformed

on the beating, normothermic heart with local cardiac wall immobilization by using the

OctopusTissueStabilizer(Medtronic,Minneapolis,MN,USA).Beforestartoftheanastomosis,

porcineheparin(150IU/kg)wasadministeredinordertoachieveanACT>250s.Heparinwas

neutralizedby1mg/kgprotaminechloride.

Patienttreatmentintheintensivecareunitwassimilarforbothgroups.Patientswereon

continuoustelemetryforatleast48hours.Whendetachedfromelectronicmonitoring,12-

leadelectrocardiogramsweremadedailyforaperiodofatleast5postoperativedaysand

in case of clinical suspicion of arrhythmia. An AF episode was defined to last for at least

one hour and was diagnosed on a physician assessment on the basis of a rhythm strip or

an electrocardiogram recording. Anticoagulation was initiated with nadroparin 2850 IU

subcutaneouslyandacetylsalicylicacid80mgdaily.AsprophylaxisforpostoperativeAFall

patientsweregivensotalol40mgtwicedailyfromthef irstdaytill1monthaftersurgery.

Measurements Blood samples were drawn with a syringe from the arterial cannula after induction of

anesthesia (baseline). The f irst 10 mL of the samples was discarded. All samples were

immediately cooled on ice and centrifuged twice at 2000*G for 15 minutes. Plasma was

storedat–80°C.QuantitativedeterminationofplasmaCRPlevelswasperformedbyaHigh

Sensitivity CRP assay using a nephelometer (Dade Behring, Inc., Newark, DE, USA). The

interassaycoeff icientofvariationis6.4%.12

data analysisAll analyses were done using standard computer software (SPSS 9.0, SPSS Inc. Chicago,

IL,USA).NormalityofthedistributionofcontinuousvariableswastestedbytheShapiro-

Wilk test. All data are presented as mean ± standard deviation (SD) or as medians (and

interquartileranges(IQR))fornon-normallydistributedcontinuousvariables.Becausethe

distributionofCRPlevelswashighlyskewed, logarithmictransformationofCRPwasused

forthelogisticregression.CRPlevelswerereportedasuntransformedvalues.Differences

in continuous and categorized variables were tested by unpaired t-test and chi-square

test, respectively. In addition to analysis with CRP as a continuous variable, the study

cohortwasdividedintoa low-(<3.0mg/L)andhigh-baseline(≥3.0mg/L)CRPgroup.The

cut-point of 3.0 mg/L was based on the American Heart Association/Centers for Disease

ControlandPreventionscientif icstatementsuggestingthatlevels>3mg/Lbeconsidered

high.9 In order to estimate the risk of developing AF in both groups we used Odds Ratios

chapterseven100

(OR)and95%confidenceintervals(CI).Toaccountsubsequentlyforpossiblepredictorsof

postoperativeAF(fromotherstudies) anddifferencesfoundbetweenthehighandlowCRP

groups,multivariatelogisticregressionanalysiswasused.1-3,8Firsttheassociationbetween

postoperative AF and each of the other possible predictors was quantif ied by univariate

analysis.Then,allpredictorswithp≤0.20intheunivariateanalysiswereincludedinthe

multivariatelogisticregressionmodeltogetherwithbaselineCRPlevels.

reSuLtS

PatientsClinical characteristics of patients in both groups are shown in Table 1. No patient had a

historyofAForuseddigoxin.

Baseline CrP levelsTherewerenodifferencesinbaselineCRPlevelsbetweenthetwoprocedures(CPB:1.4(0.9-

4.1)versusoff-pump:1.9(1.0-3.8)mg/L).

Afteroperation,34patientsdevelopedAF,ofwhich22intheCPBgroup,and12intheoff-

pump group. To determine whether pre-operative CRP levels were associated with AF, we

subdividedbothgroupsinalow-andahigh-baseline(<3.0or≥3.0mg/L)CRPgroup.

Whenbothsurgicalprocedureswerecombined,AFoccurredin15outof105patients(14%)

inthelow-baselineCRPgroupversus19outof47patients(40%)inthehigh-baselineCRP

group(crudeOR[95%-confidenceinterval]4.1[1.8-9.1];Table2)

IntheCPBgroup,11ofthe53patients(21%)withlowpreoperativeCRPlevelsdeveloped

postoperative AF, in comparison with 11 of the 20 patients (55%) with high baseline CRP

levels(p=0.004).Intheoff-pumpgroupatrialf ibrillationoccurredin4ofthe52patients

(8%)withlowbaselineCRPlevelsandin8ofthe27patients(30%)withhighbaselineCRP

levels(p=0.01).ThecrudeORforAFasafunctionofbaselineCRPwas4.7.[1.5-14.1]inthe

CPBgroupand5.1[1.4-18.8]intheoff-pumpgroup(Table2).

Multivariate logistic regressionContinuousbaselineCRPwasasignif icantpredictorofAFintheunivariatemodel.Basedon

knownpredictorsfromotherstudiesanddifferencesfoundbetweenthehighandlowCRP

groups, we then used a multivariate logistic regression to look for possible confounders

(Table 3). 1-3,8 Only continuous baseline CRP, age and type of surgery were signif icant

predictors in the model. Hypertension, peripheral vascular disease, use of β-blockers,

hypercholesterolaemia, chronic obstructive pulmonary disease (COPD) and chronic renal

failure(asmeasuredwithcreatininelevels)didnotcorrelatewiththeoccurrenceofAF.The


table 1. Baseline characteristics of CrP-groups

Baseline CrP (mg/L)

CPB p- off-pump p- Both groups p-

Low High value Low High value Low High value

(<3.0) (≥3.0) (<3.0) (≥3.0) (<3.0) (≥3.0)

n=53 n=20 n=52 n=27 n=105 n=47

Age(years) 60±10 63±7 0.04 60±9 66±7 0.01 60±10 65±7 <0.01

Malesex(%) 77 80 0.81 67 52 0.18 72 64 0.29

Weight(kg) 84±13 80±12 0.57 81±12 81±130.79 83±12 80±12 0.99

CCSclassIIIorIV(%) 53 40 0.33 44 48 0.74 49 45 0.66

PreviousMI(%) 17 30 0.22 44 26 0.11 31 28 0.73

Historyofsmoking(%) 73 80 0.47 73 74 0.92 72 77 0.59

Hypercholesterolaemia(%) 68 80 0.31 81 55 0.02 75 66 0.29

Hypertension(%) 42 55 0.30 42 52 0.42 42 53 0.20

Diabetes(%) 13 5 0.32 8 15 0.32 11 11 0.98

Periph.vasc.disease(%) 9 30 0.03 4 19 0.03 7 23 <0.01

COPD(%) 8 5 0.70 4 15 0.08 6 11 0.28

Useofβ-blockers(%) 80 90 0.28 92 89 0.61 86 89 0.54

Creatinine(mmol/L) 92±14 100±35 <0.01 88±12 89±180.85 90±13 94±27 <0.01

Intraoperative data

Cross-clamptime(min) 43±18 47±17 0.62

TimeonCPB(min) 64±22 69±21 0.98

TimeinOR(h) 3.9±0.74.0±0.7 0.85 4.2±1.0 4.4±1.10.75 4.0±0.9 4.2±0.9 0.80

Usedinotropicagents(%) 17 5 0.18 12 26 0.10 14 17 0.68

Dataarepresentedasnumbers(percentage),mean±SD.CCS,CanadianCardiovascularSociety;COPD,

chronicobstructivepulmonarydisease;CPB,cardiopulmonarybypass;CRP,C-reactiveprotein;MI,myocardialinfarction;

OR,operatingroom;Periph.vasc.disease,peripheralvasculardisease

chapterseven102

table 2.Baseline CrP levels as a risk indicator of postoperative atrial fibrillation in patients

undergoing on-pump and off-pump CABG

Baseline CrP CPB off-pump Both groups

AF AF AF

< 3.0 mg/L 11/53(21%) 4/52(8%) 15/105(14%)

≥ 3.0 mg/L 11/20(55%) 8/27(30%) 19/47(40%)

total 22/73(30%) 12/79(15%) 34/152(22%)

Crude or 4.7[1.5-14.1] 5.1[1.4-18.8] 4.1[1.8-9.1]

Adjusted or 4.6[1.4-15.3] 3.7[0.9-14.7] 3.3[1.4-7.6]

AF,atrialf ibrillation;CABG,coronaryarterybypassgrafting;CPB,cardiopulmonarybypass;CRP,C-reactive

protein;OR,oddsratio[95%conf idenceinterval];adjustedOR,oddsratioadjustedforgenderandage

adjustedORforthehigh-baselineCRPgroupcorrectedforageandgenderwas3.3[1.4-7.6]

for both procedures together. The adjusted OR’s for high baseline CRP was 4.6 [1.4-15.3]

withCPBand3.7[0.93-14.7]intheoff-pumpgroup(Table2).

Anti-arrhytmhmic therapy and length of stayInallpatientswhodevelopedpostoperativeatrialf ibrillation,thef irststepwastoincrease

sotalol dosage with steps of 40 mg (to a maximum of 80 mg three times daily). This was

usually suff icient to convert back to sinus rhythm. In 5 patients, additional digoxin was

used(allwithahigh-baselineCRP:2intheCPBgroupand3intheoff-pumpgroup).Electric

cardioversionwasusedin6patients.Nootheranti-arrhythmicdrugssuchasamiodarone

orverapamilwereused.

When leaving the hospital, only four patients still had AF. These four patients all had

high-baseline CRP levels (one in the CPB group and three in the off-pump group). There

wasasignif icantdifferenceinlengthofhospitalstaybetweenpatientswithandwithout

postoperativeAF(medianlength(interquartilerange)7.0(6.0-8.0)and6.0(5.0-7.0)days,

respectively;p<0.001).However,wecouldnotdemonstrateanydifferencesbetweenthe

low-andhigh-baselineCRPgroups(medianstay6.0(5.0-7.0)daysinbothgroups,p=0.48).


CoMMent

Inthepresentstudy,patientswithhighpre-operativeCRPlevelshadanincreasedriskof

developingAFaftercoronarybypasssurgery.Thisaccountedforbothon-pumpandoff-pump

procedures.ContinuousbaselineCRPwasanindependentpredictorforAFinamultivariate

logisticregressionmodel,controllingforageandtypeofsurgery.

Postoperative AF occurs frequently after CABG and represents one of the most common

complications of surgical myocardial revascularization. The reported incidences varies

between20%and40%inpatientsundergoingCABGanditisassociatedwithincreasedrisk

ofstroke,renaldysfunction,prolongedhospitalstay,andincreasedcosts.1,2Prophylactic

drugtreatmentwithβ-adrenergicantagonists,sotalolandamiodaronehasbeenshownto

reduce the incidence of postoperative AF and also non-pharmacological strategies such

asatrialpacinghavebeendeveloped.13,14Preoperativerecognitionofpatientswithahigh

risk of developing postoperative AF could be of considerable value. Limiting (additional)

prophylacticanti-arrhythmicsonlytoahigh-riskgroupcouldreducethenumbertotreat

reported in the literature, leading to lessovertreatmentandpossible reductions inside-

effectsandcosts.

The pathogenesis of postoperative AF appears to be of multicausal origin. Many pre- and

postoperativefactorshavebeensuggestedtoinfluenceitsoccurrence,butonlyadvanced

agehasshowntobeaconsistentpredictorforAF.Otherdemographicandclinicalriskfactors

suchasmalegender,hypertension,historyofAF,COPD,valvesurgery,chronicrenalfailure,

andhistoryofheart failurehavealsobeenreported.1,2,4Thepresentstudyalso identif ies

advancedageasapredictorofAF,nexttobaselineCRPandtypeofsurgery(table3).Some

studies suggest that an identif iable electrophysiological substrate, e.g prolonged atrial

activationordispersionofatrialrefractorinessispresentinpatientswhoareathighestrisk

of postoperative AF.15,16 Perioperative factors, such as inadequate myocardial protection,

electrolyteimbalance,β-blockerwithdrawal,changeinautonomictonemayprecipitateAF

inthesepatients.Recently,Amarandcolleaguesdemonstratedthatpatientswhodeveloped

postoperativeAFhaddifferentpostoperativeheartratevariabilitythanpatientswithout

postoperativeAF,indicatingthatautonomicinfluencesplayaroleintheinitiationofAF.17

ThereisincreasingevidencethatAFisassociatedwithaninflammatorystate.5-8,18SerumCRP

levelscanreflectthisinflammatorystateandhighlevelshavebeenshowntoconstitutean

independentcardiacriskfactor.9,18,19BesidetheevidencethatelevatedbaselineCRPlevels

in healthy persons may lead to cardiac complications, also the course after myocardial

infarction may be more complicated.20 Furthermore, several studies demonstrated a

relation between the changes in inflammatory response and the occurrence of AF during

cardiac surgery.5,7 Gaudino and colleagues demonstrated that the -174G/C Interleukin-6

chapterseven104

table 3. Postoperative atrial fibrillation by logistic regression analysis

Predictor All no AF AF univariate Multivariate

analysis analysis

(n=156) (n=122) (n=34) or [95%-CI] p-value or [95%-CI] pvalue

Age,mean(SD)(years) 61(10) 60(9) 67(8) 1.10[1.04-1.15] <0.001 1.11*[1.03-1.16] 0.001

Femalesex(%) 30 29 32 1.19[0.52-2.70] 0.68

Diabetes(%) 12 13 6 0.41[0.09-1.90] 0.26

Hypercholesterolemia(%) 71 74 59 0.51[0.23-1.12] 0.09 0.69*[0.28-1.71] 0.42

Periph.vasculardisease(%)12 12 12 1.03[0.32-3.36] 0.96

No.diseasedcoronaryart. 2.1 2.1 2.0 0.85[0.50-1.45] 0.55

DiseasedRCA(%) 61 61 62 1.07[0.57-2.00] 0.83

GraftRCA(%) 57 57 56 1.06[0.54-2.08] 0.86

Incompleterevasc.RCA(%) 11 11 12 1.03[0.45-2.39] 0.94

Hypertension 46 44 53 1.41[0.66-3.03] 0.37

COPD 7 6 12 2.19[0.60-7.98] 0.23

Serumcreatinine(mmol/L) 91(18) 90(14) 93(28) 1.01[0.98-1.03] 0.46

Useofβ-blockers 87 89 79 0.46[0.17-1.26] 0.13 0.69*[0.22-2.19] 0.53

Usedinotropicagents 16 13 24 2.02[0.78-5.22] 0.15 2.23*[0.71-7.02] 0.25

Off-pumptreatment 51 56 35 0.43[0.20-0.95] 0.04 0.27*[0.11-0.69] 0.01

BaselineCRPlevel(mg/L) 1.8 1.6 4.0 1.58[1.10-2.28] 0.01 1.57[1.06-2.32] 0.02

(IQR) (0.9-4.1)(0.9-2.7)(1.0-7.3)

BaselineCRP≥3.0mg/L(%) 22 14 40 4.1[1.83-9.05] <0.001 (4.64[1.76-11.0] 0.001)

*OR’sinmultivariateanalysiswithcontinuousbaselineCRPascovariate.

Dataarepresentedaspercentages,means(standarddeviation(SD))ormedians(interquartilerange(IQR)).

AF,atrialf ibrillation;CI,conf idenceinterval;COPD,chronicobstructivepulmonarydisease;CRP,C-reactiveprotein;Incompleterevasc.,

incompleterevascularized;No.diseasedcoronaryart.,numberofdiseasedcoronaryarteries;OR,oddsratio;Periph.vasculardisease,

peripheralvasculardisease;RCA,r ightcoronaryartery

promotergenevariantappearstomodulatetheinflammatoryresponsetocardiacsurgery

with CPB and that it influences the development of postoperative AF.5 The association

between administering non-steroidal anti-inflammatory drugs after CABG and a reduced

riskofdevelopingAFfurthersupportsthetheorythatinflammationmaycontributetoits

pathogenesis.4

In our previous study, we demonstrated that activation of the classical complement

pathway after coronary artery bypass surgery involved CRP and that changes in levels of

CRP, complement and complement-CRP complexes during the f irst days following CABG

surgerycorrespondedtopostoperativearrhythmia.7Inaddition,CRPlevelsonthesecond

postoperativedaycorrelatedtobaselineCRPlevels,suggestingthatonecoulddistinguish

“high-CRP responders” from “low-CRP responders” by baseline CRP levels. Our present

study demonstrates that (continuous) baseline CRP is an independent predictor for the

development of postoperative AF in a multivariate logistic regression model and that

patientswithhighbaselineCRPlevelshaveamorethan3timeshigherriskofdeveloping

AF,evenaftercorrectionofage.

The precise mechanism in which inflammation contributes to the development of AF

remains unclear. In patients with high baseline CRP levels, more postoperative CRP

molecules may localize in atrial tissue, where they promote local complement activation

and thus tissue damage, which can lead to fluctuations in the membrane potential.21 The

ligand for CRP remains unknown. In the presence of Ca2+ ions, CRP specif ically binds to

phosphatidylcholine,inparticularwhensomelysophosphatidylcholineispresent.22,23Hence,

asupposedligandforCRPininflamedtissuesmaybethemembranesofflip-floppedcellsor

microvesiclesderivedfromthesemembranesbyhydrolizationbysecretoryphospholipase

2 (PLA-2).24 Long-chain acylcarnitines and lysophosphatidylcholines are generated from

phosphatidylcholinebyPLA-2enzymesandcanbothcontributetomembranedysfunction

byinhibitingtheexchangeofsodiumandcalciumionsinsarcolemmalvesiclesandthuslead

tothedevelopmentofarrhythmia.25Thismayexplaintheassociationbetweenraisedlevels

ofCRPandtheoccurrenceofAF.

Withthisstudy,wearealsothef irsttodemonstratethatthecorrelationbetweenCRPlevels

andpostoperativeAFisnotCPB-dependent,asitwaspresentinboththeon-pumpandthe

off-pump group. In off-pump surgery, it is assumed that the expected reduced trauma,

ischaemiaandinflammationmaysignif icantlyreducetheincidenceofpostoperativeAF.26

While some studies show a marked reduction in postoperative AF with off-pump surgery,

others show comparable incidences with conventional CABG.27 Conflicting data could be

the result of the inhomogeneous mixture of patients in different states of inflammation

scheduledforcardiacsurgery.28InourstudytheincidenceofAFwaslowerintheoff-pump

thanintheCPB,butinthelargerpatientsetoftheentireOctopusStudyincidencesofAF

werethesame(on-pump29/139(21%)andoff-pump28/142(20%),p=0.79).10Therewere


chapterseven106

noadditionalselectioncriteria forourstudyandpatientsweretakenconsecutively from

thelargertrial.Analysisofthebaselinecharacteristicsofbothstudiesdidnotdemonstrate

differencesthatcouldexplainthisadequately,sowecanonlyspeculatethatdifferencesin

thepreoperativemicro-inflammatorystatecouldplayarole.

Limitations of the studyAs the Octopus-trial was designed as a pragmatic study, it compared off-pump surgery

with conventional CABG both performed as what was considered common practice in our

institutionatthattime.This includedotherfactorsassociatedwiththeon-pumpsurgery

suchastheuseofdexamethasone,returnofsalvagedbloodandtheuseofepiduralanalgesia

in the off-pump group, which may affect the relationship between inflammation and AF.

Therefore,wedecidedonlytostudybaselineCRPlevelssincetheselevelsarenotaffected

by the aforementioned variables. Our study clearly demonstrates a relationship between

baselineCRPandthe incidenceofAF inbothtypesofsurgery.Whetherthepre-operative

micro-inflammatory state, as reflected with CRP levels, leads to a higher postoperative

responsewasdemonstratedbeforeandwasnotasubjectofthepresentstudy.7

The use of steroids in the CPB group might be a confounder for the relationship between

postoperativeinflammationandAF,butitdeservesfutureinterest.Recently,Dernellisand

colleagues demonstrated in a randomized trial in a non-surgical setting that a 4-month

treatment with methylprednisolone lowers CRP levels in patients who had experienced

persistentAF,herebysuccessfullyreducingtheincidenceofrecurrentandpermanentAF.18

Inourstudy,asinglebolusofdexamethasonewasgivenintheCPBgroup,buttheincidence

of AF remained higher than in the off-pump group. Apparently, a single bolus of steroids

may only delay or have a limited effect on the postoperative inflammatory response, not

alteringtheincidenceofAF.29Alternatively,itmaybesuggestedthatnotthemagnitudeof

thepostoperativeinflammatoryresponsebuttheglobalmodif icationofthepreoperative

micro-inflammatory state is responsible for an altered incidence of AF. However, further

studiesareneededtoconfirmthesehypotheses.

Inconclusion,wewereabletodemonstratethatpatientswithhighbaselineCRPlevelshave

anincreasedriskofdevelopingpostoperativeAFafterCABGandthisaccountsforbothon-

pumpandoff-pumpprocedures.

ACKnoWLedGMentS

FundingforthisstudywasprovidedbyMedtronicInc.,Minneapolis,MN

references

1. Mathew JP, Parks R, Savino JS, Friedman AS, Koch C, Mangano DT et al. Atrial fibrillation followingcoronaryarterybypassgraftsurgery:predictors,outcomes,andresourceutilization.MultiCenterStudyofPerioperativeIschemiaResearchGroup.JAMA1996;276(4):300-306

2.ArankiSF,ShawDP,AdamsDH,RizzoRJ,CouperGS,VanderVlietMetal.Predictorsofatrialfibrillationafter coronary artery surgery. Current trends and impact on hospital resources. Circulation 1996;94(3):390-397.

3.AmarD,ZhangH,LeungDH,RoistacherN,KadishAH.Olderageisthestrongestpredictorofpostoperativeatrialfibrillation.Anesthesiology2002;96(2):352-356.

4.MathewJP,FontesML,TudorIC,RamsayJ,DukeP,MazerCDetal.Amulticenterrisk index foratrialfibrillationaftercardiacsurgery.JAMA2004;291(14):1720-1729.

5.GaudinoM,AndreottiF,ZamparelliR,DiCastelnuovoA,NassoG,BurzottaFetal.The-174G/Cinterleukin6 polymorphism influences postoperative interleukin-6 levels and postoperative atrial fibrillation. Isatrialfibrillationaninflammatorycomplication?Circulation2003;108Suppl1:II195-II199.

6.ChungMK,MartinDO,SprecherD,WazniO,KanderianA,CarnesCAetal.C-reactiveproteinelevationin patients with atrial arrhythmias: inflammatory mechanisms and persistence of atrial fibrillation.Circulation2001;104(24):2886-2891.

7.BruinsP,teVH,YazdanbakhshAP,JansenPG,vanHardeveltFW,deBeaumontEMetal.Activationofthecomplementsystemduringandaftercardiopulmonarybypasssurgery:postsurgeryactivationinvolvesC-reactiveproteinandisassociatedwithpostoperativearrhythmia.Circulation1997;96(10):3542-3548.

8.AvilesRJ,MartinDO,Apperson-HansenC,HoughtalingPL,RautaharjuP,KronmalRAetal.Inflammationasariskfactorforatrialfibrillation.Circulation2003;108(24):3006-3010.

9. Pearson TA, Mensah GA, Alexander RW, Anderson JL, Cannon RO, III, Criqui M et al. Markers ofinflammationandcardiovasculardisease:applicationtoclinicalandpublichealthpractice:AstatementforhealthcareprofessionalsfromtheCentersforDiseaseControlandPreventionandtheAmericanHeartAssociation.Circulation2003;107(3):499-511.

10.vanDijkD,NierichAP,JansenEW,NathoeHM,SuykerWJ,DiephuisJCetal.Earlyoutcomeafteroff-pump versus on-pump coronary bypass surgery: results from a randomized study. Circulation 2001;104(15):1761-1766.


12.RifaiN,TracyRP,RidkerPM.Clinicalefficacyofanautomatedhigh-sensitivityC-reactiveproteinassay.ClinChem1999;45(12):2136-2141.


chapter7108

13. Zimmer J, Pezzullo J, Choucair W, Southard J, Kokkinos P, Karasik P et al. Meta-analysis ofantiarrhythmictherapyinthepreventionofpostoperativeatrialfibrillationandtheeffectonhospitallengthofstay,costs,cerebrovascularaccidents,andmortalityinpatientsundergoingcardiacsurgery.AmJCardiol2003;91(9):1137-1140.

14. Merritt JC, Niebauer M, Tarakji K, Hammer D, Mills RM. Comparison of effectiveness of carvedilolversusmetoprololoratenolol foratrialfibrillationappearingaftercoronaryarterybypassgraftingorcardiacvalveoperation.AmJCardiol2003;92(6):735-736.

15.ZamanAG,ArchboldRA,HelftG,PaulEA,CurzenNP,MillsPG.Atrialfibrillationaftercoronaryarterybypasssurgery:amodelforpreoperativeriskstratification.Circulation2000;101(12):1403-1408.

16. Cox JL, Sundt TM, III. The surgical management of atrial fibrillation. Annu Rev Med 1997; 48:511-523.

17.AmarD,ZhangH,MiodownikS,KadishAH.Competingautonomicmechanismsprecedetheonsetofpostoperativeatrialfibrillation.JAmCollCardiol2003;42(7):1262-1268.

18. Dernellis J, Panaretou M. Relationship between C-reactive protein concentrations duringglucocorticoidtherapyandrecurrentatrialfibrillation.EurHeartJ2004;25(13):1100-1107.

19.RidkerPM,BuringJE,ShihJ,MatiasM,HennekensCH.ProspectivestudyofC-reactiveproteinandtheriskoffuturecardiovasculareventsamongapparentlyhealthywomen.Circulation1998;98(8):731-733.

20.TommasiS,CarluccioE,BentivoglioM,BuccolieriM,MariottiM,PolitanoMetal.C-reactiveproteinasamarkerforcardiacischemiceventsintheyearafterafirst,uncomplicatedmyocardialinfarction.AmJCardiol1999;83(12):1595-1599.

21.KleinRM,VesterEG,BrehmMU,DeesH,PicardF,NiederacherDetal.[Inflammationofthemyocardiumasanarrhythmiatrigger].ZKardiol2000;89Suppl3:24-35.

22.KaplanMH,VolanakisJE.InteractionofC-reactiveproteincomplexeswiththecomplementsystem.I.ConsumptionofhumancomplementassociatedwiththereactionofC-reactiveproteinwithpneumococcalC-polysaccharide and with the choline phosphatides, lecithin and sphingomyelin. J Immunol 1974;112(6):2135-2147.

23.VolanakisJE,WirtzKW.InteractionofC-reactiveproteinwithartificialphosphatidy-lcholinebilayers.Nature1979;281(5727):155-157.

24. Hack CE, Wolbink GJ, Schalkwijk C, Speijer H, Hermens WT, van den BH. A role for secretoryphospholipaseA2andC-reactiveproteinintheremovalofinjuredcells.ImmunolToday1997;18(3):111-115.

25.WuJ,CorrPB.Influenceoflong-chainacylcarnitinesonvoltage-dependentcalciumcurrentinadultventricularmyocytes.AmJPhysiol1992;263(2Pt2):H410-H417.

26.ButlerJ,ParkerD,PillaiR,WestabyS,ShaleDJ,RockerGM.Effectofcardiopulmonarybypassonsystemicreleaseofneutrophilelastaseandtumornecrosisfactor.JThoracCardiovascSurg1993;105(1):25-30.

References 109

27.ArchboldRA,CurzenNP.Off-pumpcoronaryarterybypassgraftsurgery:theincidenceofpostoperativeatrialfibrillation.Heart2003;89(10):1134-1137.

28.RossR.Atherosclerosis--aninflammatorydisease.NEnglJMed1999;340(2):115-126.

29.JansenNJ,vanOeverenW,vanVlietM,StoutenbeekCP,EysmanL,WildevuurCR.Theroleofdifferenttypesofcorticosteroidsontheinflammatorymediatorsincardiopulmonarybypass.EurJCardiothoracSurg1991;5(4):211-217.

Chapter eight

General discussion 8

chaptereight112

Hypothesis and findings of this thesis

Theaimofthisthesiswastostudytheactivationofhemostasisandinflammation,inpatients

undergoing off-pump (OPCAB) and on-pump coronary artery bypass graft (CABG) surgery

andtherelationshipofcoagulationandinflammationtoclinicaloutcome.Wehypothesized

that activation of hemostasis and C-reactive protein (CRP) would be more pronounced in

patients undergoing CABG using cardiopulmonary bypass (CPB) and that this would be

associated with increased morbidity. In particular, neurocognitive dysfunction may be

lesspronouncedinpatientsundergoingOPCABprocedures.Therefore,wedidanumberof

studiesinwhichweinvestigatedseveralaspectsofhemostasisinpatientsundergoingon-

andoff-pumpCABG.Moreover,theinfluenceofCRPasamarkerofinflammationwasstudied

as others have already demonstrated that CRP levels may be associated with increased

morbidityandevenincreasedmortalityaftercardiacsurgery.1-4

In40patients,randomlyassignedtooff-pumpandon-pumpCABG,weobservedthatCABG

surgery with CPB was associated with increased thrombin generation and f ibrinolytic

activity in the immediate postoperative period.5 However, patients in the OPCAB-group

demonstrated a delayed postoperative response that became equal in magnitude to the

CPB group in the later (20-96 hours) postoperative period. Although early postoperative

activation of hemostasis was more pronounced after on-pump CABG, we did not f ind any

association with clinical outcome in the initial group and in a larger group of 73 CABG

patients. Therefore, the clinical impact of CPB-related activation of coagulation remains

tobedetermined.

In contrast to our hypothesis, a signif icant association between early postoperative

activation of hemostasis and the incidence of early postoperative cognitive decline was

observed in 60 OPCAB patients.6 D-dimer levels and prothrombin fragments 1.2 at two

hoursafter theoff-pumpprocedurewerestronglyassociatedwithearlycognitivedecline

onpostoperativeday4(chapter4).Severalmechanismsmayberesponsibleforthisapparent

paradox. One contributing factor may be the fact that institution of CPB can obviously

reducethehypercoagulablestateresultingfromsurgical trauma.In60on-andoff-pump

patients,wecoulddemonstratethatvonWillebrandFactor(VWF)releaseisincreasedafter

bothprocedures.However,VWFactivityissignif icantlylowerintheon-pumpgroup(chapter

5). Shear stress-induced proteolysis due to the use of CPB may be one important factor

responsibleforthisphenomenon.

Thoracic epidural analgesia (TEA) in cardiac surgical patients has many potential

advantages.TEAimproveshemodynamicstability,reducesmyocardialoxygenconsumption,

potentially decreases the incidence of intra- and postoperative myocardial ischemia and

improvesqualityofanalgesiaandpostoperativepulmonary function.7-10However, theuse

ofTEAduringon-pumpCABGislimitedbecauseoftheperceivedriskofepiduralhematoma

formation secondary to full heparinization during CPB.11 In OPCAB surgery, TEA is more

accepted,asfullheparinizationisnotnecessaryforthesurgicalprocedure.IntheOctopus

Study, the majority of the OPCAB patients received TEA in combination with general

anesthesia.Postoperativeactivationofhemostasismaybeaffectedbytheintraoperative

useofTEA.Theuseofepiduralanalgesia isassociatedwithasignif icantreductioninthe

incidenceofpostoperativethromboemboliccomplicationssuchasdeepvenousthrombosis

andpulmonaryemboli.12-14Similarreductionsareobtainedwhenlocalanestheticsareinfused

IV.15 The mechanisms for these effects are still unknown, but inflammatory mediators –

releasedinresponsetosurgicaltraumaandinducingthrombosisandvasoconstriction–are

likelytobepivotal.OneofthemediatorsaffectedbyTEAcouldbethromboxaneA2(TXA2),a

potentplateletaggregatorwhichisusuallyincreasedaftersurgery.16Localanesthetics(LA)

inhibitTXA2inexperimentalstudies.17Toverifyexperimentalresults,weconductedatrial

where we studied the effects of several LA on TXA2-induced platelet aggregation in an in

vitromodel(chapter6).However,theLAtestedhadonlylimitedabilitytoinhibitthatTXA2-

inducedplateletaggregation.Therefore,LAeffectsonTXA2-inducedplateletaggregation

areunlikely toplayamajor role in theclinicallyobservedantithromboticeffectsof local

anesthetics.

Inthisthesis,wewereunabletodemonstrateasignif icantinteractionbetweenCPB-induced

activationofhemostasis,theinflammatoryresponsetosurgeryandCPBandparametersof

clinicaloutcome.WeindeedobservedanassociationbetweenbaselineCRPlevels,amarker

forchronicinflammation,andpostoperativeatrialf ibrillationafterbothon-pumpandoff-

pumpCABG.18Apparently, therelationshipbetweenpostoperativeCRPactivationandthe

incidenceofatrialf ibrillation(AF)isnotCPB-dependent.

Hypercoagulable state after off-pump CABG

Activation of hemostasis after conventional CABG is bi-phasic. Firstly, despite full

heparinization, there is intense activation of hemostatic mechanisms due to the use of

CPB.19-21Bothcontactofhumanbloodwithnon-endothelialsurfacesoftheextracorporeal

circulation, and the release and re-infusion of tissue factor lead to increased thrombin

generationduringcardiopulmonarybypass.20-22Secondly,inthelaterpostoperativeperiod

(severalhourstodays),thesurgicaltraumaismainlyresponsiblefortheactivationofthe

coagulation cascades.5,23,24 Intraoperative activation of hemostasis in OPCAB surgery is

signif icantly reduced compared to conventional CABG. The coagulation and f ibrinolysis

cascades,however,aresubsequentlyactivatedinthepostoperativeperiod,af indingwhichis

comparablewithothermajorsurgicalproceduresandwithconventionalCABG.5,23-25Patients

undergoing OPCAB surgery lack the hemostatic abnormalities caused by the CPB system

itself,e.g.plateletdysfunction,proteolysisofvonWillebrandFactoranddirectactivation

of f ibrinolysis.26-28Thesepatientsare thereforemore likely todevelophypercoagulability

states postoperatively than patients undergoing on-pump CABG. One possible advantage

Generaldiscussion 113

chaptereight114

ofthisstateof“preservedhemostasis”,assomereferto,isthatpreservedhemostasiscan

contributetoareducedpostoperativebloodlossanddecreasedtransfusionrequirements

inOPCABpatients.29-32Concurrentlyhowever,thepostoperativehypercoagulablestateafter

OPCABmayalsobeanareaofconcern,becauseitstillmaycontributetothromboembolic

complications.

How strong is the evidence linking an early postoperative hypercoagulable state to

thromboembolic events? At f irst glance, this does not appear to be a major problem.

Extensiveclinicalexperiencehasshownthatthrombo-emboliccomplicationssuchasdeep

venousthrombosis,pulmonaryembolismorarterialthrombosisoccurveryrarelyafteroff-

pumpCABG.33Nonetheless,theresultsofourstudiesdemonstratedanassociationbetween

earlypostoperativeD-dimerlevelsandcognitivedeclinefourdaysaftertheoperation.These

f indingsindicatethatthepostoperativehypercoagulablestatecanbearelevantfactorin

thedevelopmentofearlyneurocognitivedecline.Itisconceivablethatthehypercoagulable

stateafteroff-pumpCABGcontributestomoreandlongerlastingorgandamageinhigh-risk

patients (older patients with more co-morbidity). Furthermore, the association between

early postoperative D-dimer levels and early cognitive decline is in accordance with the

hypothesisthatearlypostoperativeactivationofhemostasismayplayaroleintheaetiology

ofpostoperativeischaemiccomplications.Bottigeretal.recentlydemonstratedarelation

betweenearlypostoperativecoagulationactivationandperioperativemyocardialischemia

in patients undergoing vascular surgery.34 Moreover, Mangano et al. showed that aspirin

administeredwithin48hoursaftercoronaryarterybypassgraftsurgeryisassociatedwith

a reduced incidence of postoperative ischaemic complications.35 In addition, therapies

promoting coagulation, such as transfusion of coagulation factors, and antif ibrinolytic

agentswerealsoassociatedwithan increasedriskofpostoperativeorgan failure.35,36The

authorssuggestedthat inhibitionof theprocoagulatoryresponseandplateletactivation

causedbythesurgicalstimulus,maypreventadherencetodisruptedvascularendothelium,

intravascularthrombosisandsubsequentorganischaemia.Finally,thelong-termpatency

ofgraftsisonemajordeterminantofperioperativeoutcomeinpatientsrequiringcardiac

surgery.Theprimarygraftpatencyratesexceeds90%,thereforecomplicationswithacute

graftclosurearenotamajorconcern.37,38However,thevenousgraftpatencyat1-yearfollow

up was 88% in patients undergoing CABG surgery, 87% in patients undergoing on-pump

beatingheartsurgeryand68%inpatientsundergoingoff-pumpsurgery(p<0.01).37Multiple

pathologicandclinicalstudieshaveshownthatveingraftdiseasetakesmanyforms:acute

thrombosis, subacute intimalhyperplasiaandchronicgraftatherosclerosis.39Although it

takes months for intimal hyperplasia to develop, and at least 1 year for atherosclerosis,

theinitiatingevents(intimalinjury,plateletactivation,thrombusformation,macrophage

inf iltration, and smooth muscle activation) all occur in the acute postoperative period.

Therefore,duringtheearlypostoperativeperiod,evenintheabsenceofclinicallymanifest

adverseevents,thegroundworkmaybelaidfortheoccurrenceofmultiplelateevents,thus

adverselyimpairinglong-termgraftpatency.

CPB-induced activation of hemostasis and CrP response and relation to clinical outcome

Althoughwefoundsignif icantlymorethrombingenerationandsubsequentf ibrinolysisin

theimmediatepostoperativeperiodafteron-pumpCABG,wewerenotabletodemonstrate

a correlation with perioperative mortality, stroke, myocardial infarction and cognitive

decline.Severalexplanationscanbeadvanced.

First, the incidence of complications such as perioperative mortality, stroke, and

myocardialinfarctionintheOctopusStudywasverylow,renderingthestudystatistically

underpoweredtof indanyassociationswithmajorclinicalevents.40Secondly,theOctopus

Study was designed as a pragmatic rather than an explanatory trial: the study compared

off-pumpsurgerywithconventionalCABG,bothperformedaccordingtostandardpractice

intheNetherlandsatthattime.41Unfortunately,thisincludedtheuseofdexamethasonein

theon-pumpgroupbutnotintheoff-pumpgroup,whichmadeitimpossibletomeasurethe

inflammatoryresponsesolelycausedbytheuseoftheCPB.

Incontrasttotheoff-pumpgroup,noassociationbetweenearlypostoperativeactivation

of hemostasis and cognitive decline could be demonstrated in the on-pump CABG group.

This was unexpected, as we assumed that more pronounced thrombin generation in

the immediate postoperative period after on-pump CABG would also lead to a stronger

associationwithearlypostoperativecognitivedecline.Althoughpostoperativecognitive

decline has been studied extensively in on-pump CABG patients42-45, only one study has

previously investigated the association between a postoperative hypercoagulable state

and cognitive decline.46 Westaby and colleagues measured perioperative inflammatory

markersandmarkersofcoagulationandf ibrinolysis in100patientsundergoingon-pump

CABG, and did not f ind an association with postoperative cognitive performance after

either5daysor3months.46Possibleexplanationsincludetheaforementioneddisturbances

ofhemostasisresultingfromtheheart-lungmachinee.g.plateletdysfunction,proteolysis

ofvonWillebrandFactoranddirectactivationoff ibrinolysis.26-28Thesemechanismsmight

reduce the thrombo-embolic risk and even lead to an increased bleeding tendency.47,48

Secondly, with the use of cardiotomy suction, highly activated blood is re-introduced in

the circulation. The mediastinal shed blood contains D-dimers formed by the breakdown

ofcross-linkedf ibrin inthewoundareaandmaythus leadtoartif iciallyelevatedplasma

levels.49 Thirdly, the pathogenesis of neurocognitive decline after on-pump surgery may

be different from off-pump surgery. When using a controlled definition (i.e., using a

concurrent control group of patients not undergoing surgery), the incidence of cognitive

declineafteron-pumpCABGintheOctopusStudyissurprisinglysimilartoelderlypatients

(medianageof68years)undergoingnon-cardiacsurgery:11.7%oftheCABGpatients(in


chaptereight116

the Octopus-study) and 9.9% of non-cardiac surgery patients (in the ISPOCD-study) had

cognitivedeclineat3months.50,51Thissuggeststhatthedistinctionbetweenconventional

CABG and non-cardiac surgery with respect to cognitive decline is not that substantial.

However, other pathophysiological aspects related to the CPB procedure may also play a

role. In addition to hypoperfusion, intraoperative microembolism appears to be a major

mechanism.52TheuseoftheCPBsystem,theuseofcardiotomysuction,theclampingand

cannulationofacalcif iedaortacanleadtoembolisationwithgasbubbles,atherosclerotic

material,plateletaggregatesandfat-containingparticles.Ithasbeendemonstratedthat

the number of intraoperative cerebral microemboli is signif icantly decreased when CABG

is performed off-pump.53-55 Nonetheless, no relation between the number of microemboli

andcognitivedeclineorischemicbrainlesionsoncerebralmagneticresonanceimaginghas

beenfound.53,54

It has been demonstrated earlier that on-pump CABG causes a biphasic complement

activation.2 First, the complement and the cytokine systems are activated from the

interactionofbloodwiththeextracorporealcircuitduringtheprocedure.Thesecondphase

occursduringthe f irst5daysaftersurgeryand involvesCRP.Thisphenomenon is related

to baseline CRP levels and is associated with clinical symptoms such as arrhythmia’s.2

In our study, we could not demonstrate that the correlation between CRP levels and

postoperative AF depends on the use of CPB: patients undergoing conventional CABG

and patients undergoing OPCAB procedures developed AF to a comparable degree. These

results are somewhat surprising, as initial studies suggested that CRP activation was the

resultoftheinteractionofbloodwiththeextracorporealcircuitandthatreducedtrauma,

ischaemiaandinflammationinoff-pumpsurgerywouldsignif icantlyreducetheincidenceof

postoperativeAF.2,56However,theevidencethatOPCABisassociatedwithalowerincidence

of AF than conventional CABG is still inconclusive. While some studies showed a marked

reductioninpostoperativeAFwithoff-pumpsurgery,othersshowedincidencescomparable

with conventional CABG.57 In our study, the use of steroids in the CPB group might have

influencedtheresultswhentherelationshipbetweenpostoperative inflammationandAF

isstudied.However,thiscannotexplainourf indingsentirely:asinglebolusofhigh-dose

dexamethasonewasgivenonlyintheCPBgroup,buttheincidenceofAFremainedhigherin

theon-pumpgroupthanintheoff-pumpgroup.Apparently,asinglebolusofsteroidsmay

only delay or have a limited effect on the postoperative inflammatory response, without

alteringtheincidenceofAF.58Alternatively,itmaybesuggestedthatnotthemagnitudeof

thepostoperativeinflammatoryresponsebuttheglobalmodif icationofthepreoperative

micro-inflammatory state is responsible for an altered incidence of AF. In addition, the

pathogenesisofpostoperativeAFismulticausalinorigin.Otherdemographicandclinical

riskfactorssuchasadvancedage,malesex,hypertension,historyofAF,chronicobstructive

pulmonarydisease,chronicrenalfailure,beta-blockerwithdrawal,electrolytedisturbances

andhistoryofheartfailurehavebeenreportedtoinfluencetheoccurrenceofAF.Inourstudy,

baselineCRPandadvancedageweretheonlyindependentpredictorsforthedevelopment

ofpostoperativeAFinamultivariatelogisticregressionmodel.However,ourstudydidnot

haveenoughpowertoexcludetheroleofmostoftheaforementionedfactors;therefore,we

havetoconcludethatthedevelopmentofAFmayonlybeinpartinflammation-related.

Limitations

In the present studies, we were the f irst to demonstrate associations of activation of

hemostasiswithrelativelyminorclinicalendpointssuchasearlycognitivedeclineandatrial

f ibrillation.However,wewerenotabletodemonstrateanyinteractionbetweenactivation

ofhemostasisandmajorclinicaleventssuchasstroke,myocardialinfarctionanddeathin

ourstudies.Thiscaninpartbeexplainedbytheverylowcomplicationrateinbothgroups

oftheOctopusstudy,becausetheparticipantswererelativelyyoungandhealthy(average

age:61.3years).40Furthermore,theincidenceofcognitivedeclineafter3and12monthswas

also lower than expected after both on- and off-pump CABG.44 In addition, perioperative

bloodsamplinghadstartedafternearlyhalfofthepatientswerealreadyincluded,which

furthercontributedtothelackofstatisticalpower.Nevertheless,theresultsofourstudies

maystillbeofclinicalvalue,becauseearlycognitivedeclineandAFarepredictorsofmore

seriousmorbidity.59-62

Secondly,theOctopusStudywasdesignedasapragmatictrial,i.e.,atrialcomparingtwo

clinical strategies.41 This meant that factors other than the use of the CPB system could

influenceourdata.Morespecif ically,theon-pumpprocedurewasperformedwith1)useof

dexamethasone2)useofmoderatehypothermia3)useofcardioplegiatoarresttheheart

and4)useofcardiotomysuction.IntheOPCABgroup,nopatientreceiveddexamethasone,

adifferentanticoagulationstrategywasused(targetACT>250svs450s)and75%ofthe

patientsreceivedTEA.Thedecisiontoapplyepiduralanalgesiawasbasedonthepreference

oftheindividualattendinganesthesiologist.EvenifTEAwouldhaveaffectedourresults,

thefactthatallocationtoTEAwasnon-randommayhaveobscuredsuchaneffect.Amore

explanatorydesignofthestudy,inwhichtheuseofCPBistheonlydifferencebetweenthe

twotreatmentgroupswouldhaveavoidedtheseproblemsofinterpretation.

Theselimitationsshouldbetakenintoaccountwheninterpretingourdata.Theconclusions

of this thesis should therefore be considered as “hypothesis-generating”, and further

studiesareneededtoconfirmthesehypotheses.

Future studies

In the last years, several studies have compared postoperative hemostatic parameters

afteron-pumpandoff-pumpCABGinarandomizedfashionandallareinaccordancewith

the results of the present thesis.5,19,24,63,64Even a larger number of randomized controlled


chaptereight118

trials have examined the inflammatory response after on- and off pump CABG. Numerous

inflammatorymarkers(e.g.tumornecrosisfactorα,complementproteins,andinterleukins

(IL-1,IL-6, Il –8, IL 10)) have been studied. Consistent f indings are that some markers of

inflammation are reduced after off-pump surgery, but only in the early hours after the

surgicalprocedure.65-67Themainlimitationofthemajorityofthesetrialsistheenrollmentof

smallpatientnumbers(20to30patientsinaverage).Thismakesitnearlyimpossibletof ind

associationsbetweenbiologicaldataandclinicalendpoints.Alarge,adequatelypowered

trial is needed to study the relationship between clinical outcome and postoperative

activationofhemostasisafteron-versusoff-pumpCABG.Nodoubt,thisrepresentsavery

complex f ield of investigation, which needs well-designed strict protocols. In addition,

it imposes a heavy workload on staff, because of frequent blood sampling and analyses

that can only be conducted in highly specialized laboratories. Nonetheless, in order to

answerthequestionifreducedperioperativeinflammationafterOPCABimprovesoutcome,

randomizedtrialswillbenecessary.

Until now, little is known about the hypercoagulable state immediately after OPCAB

surgery.Therefore,carefullyconductedstudiesareneededtostudytherelationbetween

coagulation and complications in this group of patients. Management of anticoagulation

inOPCABpatientsvariesconsiderably,andthereisnoacceptedstandardhowantiplatelet

agents should be administered throughout the perioperative period.68 In view of the

lower incidence of postoperative bleeding complications, a study might be performed

that answers the question if intraoperative reversal of heparin can be safely omitted.29

In view of the well-documented unresponsiveness to aspirin, as well as the considerable

effectivenessofthienopyridines(ticlopidineanditssafersuccessorclopidogrel)reported

in both the cardiology and cardiac surgical literature, serious consideration should be

giventoexaminingtheeffectsoftheuseofclopidogrelduringanddirectlyafteroff-pump

CABG.69-71

In this study, we found that both baseline inflammatory (e.g. CRP) as hemostatic (e.g.

VWFactivity)markerswererelatedtopostoperativeactivationandclinicalparameters.6,18

Apparently, these baseline levels represent a subclinical micro-inflammatory or

prothrombotic state without clinical symptoms. Nevertheless, these f indings deserve

someconsideration.Theyare inaccordancewith thehypothesis thatonecandistinguish

high- from low-responders in patients undergoing surgery on the basis of their baseline

levels. Preoperative recognition of patients with a high risk of developing postoperative

complications may thus be possible. Moreover, limiting prophylactic drugs to a high-risk

groupcouldleadtolessovertreatmentandpossiblereductionsinside-effectsandcosts.

Also genetic factors may play role in this. Gaudino and colleagues demonstrated that

the –174G/C interleukin-6 promoter gene variant appears to modulate the inflammatory

response to cardiac surgery with CPB and the occurrence of atrial f ibrillation.72 Further

studiesareneededtodetermineparametersthatcanpredictthepatient’sreactiontothe

surgicaltrauma.Thelong-termgoalshouldbeanindividualinflammatoryandhemostatic

profileforeachpatientundergoingsurgerycombinedwitha individualprophylacticdrug

regimentopreventcomplications.

Conclusions

CABG surgery with CPB is associated with excessive thrombin generation and f ibrinolytic

activity in the immediate postoperative period. After off-pump surgery, a delayed

postoperativeactivationofhemostasisthatbecomesequalinmagnitudeinthelater(20-

96 hours) postoperative period is found and may indicate a hypercoagulable state. Off-

pumpCABGisalsoassociatedwithrelativelyincreasedpostoperativevonWillebrandfactor

activity. In addition, early postoperative activation of hemostasis is associated with the

incidenceofearlypostoperativecognitivedeclineafteroff-pumpCABG.Localanesthetic

effectsonthromboxane-inducedearlyplateletaggregationareunlikelytoplayamajorrole

inclinicallyobservedantithromboticeffectsoflocalanesthetics.

Future randomized studies are essential and should focus on the clinical impact of the

activationofhemostasisafterbothon-andoff-pumpCABG.Extraconsiderationshouldbe

giventothemanagementthehypercoagulablestateafteroff-pumpprocedures.



references

1.BoekenU,FeindtP,ZimmermannN,KalweitG,PetzoldT,GamsE.IncreasedpreoperativeC-reactiveprotein(CRP)-valueswithoutsignsofaninfectionandcomplicatedcourseaftercardiopulmonarybypass(CPB)-operations.EurJCardiothoracSurg1998;13(5):541-545.

2.BruinsP,teVH,YazdanbakhshAP,JansenPG,vanHardeveltFW,deBeaumontEMetal.Activationofthecomplementsystemduringandaftercardiopulmonarybypasssurgery:postsurgeryactivationinvolvesC-reactiveproteinandisassociatedwithpostoperativearrhythmia.Circulation1997;96(10):3542-3548.

3.KangasniemiOP,BiancariF,LuukkonenJ,VuorisaloS,SattaJ,PokelaRetal.PreoperativeC-reactiveproteinispredictiveoflong-termoutcomeaftercoronaryarterybypasssurgery.EurJCardiothoracSurg2006;29(6):983-985.

4.BiancariF,LahtinenJ,LepojarviS,RainioP,SalmelaE,PokelaRetal.PreoperativeC-reactiveproteinandoutcomeaftercoronaryarterybypasssurgery.AnnThoracSurg2003;76(6):2007-2012.

5.LoB,FijnheerR,CastigliegoD,BorstC,KalkmanCJ,NierichAP.Activationofhemostasisaftercoronaryarterybypassgraftingwithorwithoutcardiopulmonarybypass.AnesthAnalg2004;99(3):634-640.

6.LoB,FijnheerR,NierichAP,KalkmanCJ,vanDijkD.Activationofhemostasisisassociatedwithearlycognitive decline after off-pump coronary artery bypass surgery. J Thromb Haemost 2005; 3(9):2114-2117.

7. Stenseth R, Bjella L, Berg EM, Christensen O, Levang OW, Gisvold SE. Effects of thoracic epiduralanalgesia on pulmonary function after coronary artery bypass surgery. Eur J Cardiothorac Surg 1996;10(10):859-865.

8. Stenseth R, Berg EM, Bjella L, Christensen O, Levang OW, Gisvold SE. Effects of thoracic epiduralanalgesiaoncoronaryhemodynamicsandmyocardialmetabolismincoronaryarterybypasssurgery.JCardiothoracVascAnesth1995;9(5):503-509.

9.StensethR,BjellaL,BergEM,ChristensenO,LevangOW,GisvoldSE.Thoracicepiduralanalgesia inaortocoronarybypasssurgery.I:Haemodynamiceffects.ActaAnaesthesiolScand1994;38(8):826-833.

10.ScottNB,TurfreyDJ,RayDA,NzewiO,SutcliffeNP,LalABetal.Aprospectiverandomizedstudyofthepotentialbenefitsofthoracicepiduralanesthesiaandanalgesiainpatientsundergoingcoronaryarterybypassgrafting.AnesthAnalg2001;93(3):528-535.

11.HoAM,ChungDC,JoyntGM.Neuraxialblockadeandhematomaincardiacsurgery:estimatingtheriskofarareadverseeventthathasnot(yet)occurred.Chest2000;117(2):551-555.

12.ModigJ,BorgT,BaggeL,SaldeenT.Roleofextraduralandofgeneralanaesthesiainfibrinolysisandcoagulationaftertotalhipreplacement.BrJAnaesth1983;55(7):625-629.

13.ModigJ,BorgT,KarlstromG,MaripuuE,SahlstedtB.Thromboembolismaftertotalhipreplacement:roleofepiduralandgeneralanesthesia.AnesthAnalg1983;62(2):174-180.

References 121

14. Rodgers A, Walker N, Schug S, McKee A, Kehlet H, van Zundert A et al. Reduction of postoperativemortalityandmorbiditywithepiduralorspinalanaesthesia:resultsfromoverviewofrandomisedtrials.BMJ2000;321(7275):1493.

15. Cooke ED, Bowcock SA, Lloyd MJ, Pilcher MF. Intravenous lignocaine in prevention of deep venousthrombosisafterelectivehipsurgery.Lancet1977;2(8042):797-799.

16. Teoh KH, Fremes SE, Weisel RD, Christakis GT, Teasdale SJ, Madonik MM et al. Cardiac release ofprostacyclin and thromboxane A2 during coronary revascularization. J Thorac Cardiovasc Surg 1987;93(1):120-126.

17.HoenemannCW,PodranskiT,LoB,DurieuxM.LocalanestheticeffectsonthromboxaneA2signaling[abstract].Anesthesiology1998;89:A886.

18. Lo B, Fijnheer R, Nierich AP, Bruins P, Kalkman CJ. C-reactive protein is a risk indicator for atrialfibrillationaftermyocardialrevascularization.AnnThoracSurg2005;79(5):1530-1535.

19.CasatiV,GerliC,FrancoA,DellaVP,BenussiS,AlfieriOetal.ActivationofCoagulationandFibrinolysisduringCoronarySurgery:On-pumpversusOff-pumpTechniques.Anesthesiology2001;95(5):1103-1109.

20. Boisclair MD, Lane DA, Philippou H, Esnouf MP, Sheikh S, Hunt B et al. Mechanisms of thrombingenerationduringsurgeryandcardiopulmonarybypass.Blood1993;82(11):3350-3357.

21.ChungJH,GikakisN,RaoAK,DrakeTA,ColmanRW,EdmundsLH,Jr.Pericardialbloodactivatestheextrinsic coagulation pathway during clinical cardiopulmonary bypass. Circulation 1996; 93(11):2014-2018.

22. Tabuchi N, Sunamori M, Koyama T, Shibamiya A. Remaining procoagulant property of wound bloodwashedbyacell-savingdevice.AnnThoracSurg2001;71(5):1749-1750.

23.EnglbergerL,ImmerFF,EcksteinFS,BerdatPA,HaeberliA,CarrelTP.Off-pumpcoronaryarterybypassoperationdoesnotincreaseprocoagulantandfibrinolyticactivity:preliminaryresults.AnnThoracSurg2004;77(5):1560-1566.

24. Paparella D, Galeone A, Venneri MT, Coviello M, Scrascia G, Marraudino N et al. Activation of thecoagulationsystemduringcoronaryarterybypassgrafting:comparisonbetweenon-pumpandoff-pumptechniques.JThoracCardiovascSurg2006;131(2):290-297.

25.MarianiMA,GuYJ,BoonstraPW,GrandjeanJG,vanOeverenW,EbelsT.Procoagulantactivityafteroff-pumpcoronaryoperation:isthecurrentanticoagulationadequate?AnnThoracSurg1999;67(5):1370-1375.

26.RinderCS,BohnertJ,RinderHM,MitchellJ,AultK,HillmanR.Plateletactivationandaggregationduringcardiopulmonarybypass.Anesthesiology1991;75(3):388-393.

27.TanakaK,TakaoM,YadaI,YuasaH,KusagawaM,DeguchiK.Alterationsincoagulationandfibrinolysisassociatedwithcardiopulmonarybypassduringopenheartsurgery.JCardiothoracAnesth1989;3(2):181-188.


28.PerutelliP.ProteolysisofvonWillebrandfactorisincreasedduringcardiopulmonarybypass.ThrombRes2001;102(5):467-473.

29. Nader ND, Khadra WZ, Reich NT, Bacon DR, Salerno TA, Panos AL. Blood product use in cardiacrevascularization: comparison of on- and off-pump techniques. Ann Thorac Surg 1999; 68(5):1640-1643.

30. Ascione R, Williams S, Lloyd CT, Sundaramoorthi T, Pitsis AA, Angelini GD. Reduced postoperativeblood loss and transfusion requirement after beating-heart coronary operations: a prospectiverandomizedstudy.JThoracCardiovascSurg2001;121(4):689-696.

31. Gu YJ, Mariani MA, van Oeveren W, Grandjean JG, Boonstra PW. Reduction of the inflammatoryresponse inpatientsundergoingminimally invasivecoronaryarterybypassgrafting.AnnThoracSurg1998;65(2):420-424.

32.AngeliniGD,TaylorFC,ReevesBC,AscioneR.Earlyandmidtermoutcomeafteroff-pumpandon-pumpsurgeryinBeatingHeartAgainstCardioplegicArrestStudies(BHACAS1and2):apooledanalysisoftworandomisedcontrolledtrials.Lancet2002;359(9313):1194-1199.

33.CartierR,RobitailleD.Thromboticcomplicationsinbeatingheartoperations.JThoracCardiovascSurg2001;121(5):920-922.

34. Bottiger BW, Snyder-Ramos SA, Lapp W, Motsch J, Aulmann M, Schweizer M et al. Associa-tionbetweenearlypostoperativecoagulationactivationandperi-operativemyocardialischaemiainpatientsundergoingvascularsurgery.Anaesthesia2005;60(12):1162-1167.

35.ManganoDT.Aspirinandmortalityfromcoronarybypasssurgery.NEnglJMed2002;347(17):1309-1317.

36.ManganoDT,TudorIC,DietzelC.Theriskassociatedwithaprotininincardiacsurgery.NEnglJMed2006;354(4):353-365.

37.KimKB,LimC,LeeC,ChaeIH,OhBH,LeeMMetal.Off-pumpcoronaryarterybypassmaydecreasethepatencyofsaphenousveingrafts.AnnThoracSurg2001;72(3):S1033-S1037

38.ZehrKJ,HandaN,BonillaLF,AbelMD,HolmesDR,Jr.Pitfallsandresultsofimmediateangiographyafteroff-pumpcoronaryarterybypassgrafting.HeartSurgForum2000;3(4):293-299.

39. Motwani JG, Topol EJ. Aortocoronary saphenous vein graft disease: pathogenesis, predisposition,andprevention.Circulation1998;97(9):916-931.

40. van Dijk D, Nierich AP, Jansen EW, Nathoe HM, Suyker WJ, Diephuis JC et al. Early outcome afteroff-pumpversuson-pumpcoronarybypasssurgery:resultsfromarandomizedstudy.Circulation2001;104(15):1761-1766.

41.vanDijkD,NierichAP,EeftingFD,BuskensE,NathoeHM,JansenEWetal.TheOctopusStudy:rationaleanddesignoftworandomizedtrialsonmedicaleffectiveness,safety,andcost-effectivenessofbypasssurgeryonthebeatingheart.ControlClinTrials2000;21(6):595-609.

References 123

42. van Dijk D, Keizer AM, Diephuis JC, Durand C, Vos LJ, Hijman R. Neurocognitive dysfunction aftercoronaryarterybypasssurgery:asystematicreview.JThoracCardiovascSurg2000;120(4):632-639.

43. Roach GW, Kanchuger M, Mangano CM, Newman M, Nussmeier N, Wolman R et al. Adverse cerebraloutcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research GroupandtheIschemiaResearchandEducationFoundationInvestigators.NEnglJMed1996;335(25):1857-1863.


45. Lloyd CT, Ascione R, Underwood MJ, Gardner F, Black A, Angelini GD. Serum S-100 protein releaseandneuropsychologicoutcomeduringcoronaryrevascularizationonthebeatingheart:aprospectiverandomizedstudy.JThoracCardiovascSurg2000;119(1):148-154.

46. Westaby S, Saatvedt K, White S, Katsumata T, van Oeveren W, Halligan PW. Is there a relationshipbetweencognitivedysfunctionandsystemicinflammatoryresponseaftercardiopulmonarybypass?AnnThoracSurg2001;71(2):667-672.

47.GelbAB,RothRI,LevinJ,LondonMJ,NoallRA,HauckWWetal.Changesinbloodcoagulationduringandfollowingcardiopulmonarybypass:lackofcorrelationwithclinicalbleeding.AmJClinPathol1996;106(1):87-99.

48.ComunaleME,CarrJM,MoormanRM,RobertsonLK.SignificanceofD-dimerconcentrationsduringandaftercardiopulmonarybypass.JCardiothoracVascAnesth1996;10(4):477-481.

49.TabuchiN,deHaanJ,BoonstraPW,vanOeverenW.Activationoffibrinolysisinthepericardialcavityduringcardiopulmonarybypass.JThoracCardiovascSurg1993;106(5):828-833.

50.KeizerAM,HijmanR,KalkmanCJ,KahnRS,vanDijkD.Theincidenceofcognitivedeclineafter(not)undergoing coronary artery bypass grafting: the impact of a controlled definition. Acta AnaesthesiolScand2005;49(9):1232-1235.

51.MollerJT,CluitmansP,RasmussenLS,HouxP,RasmussenH,CanetJetal.Long-termpostoperativecognitivedysfunctionintheelderlyISPOCD1study.ISPOCDinvestigators.InternationalStudyofPost-OperativeCognitiveDysfunction.Lancet1998;351(9106):857-861.

52.NewmanSP,HarrisonMJ.Coronary-arterybypasssurgeryandthebrain:persistingconcerns.LancetNeurol2002;1(2):119-125.

53.LundC,HolPK,LundbladR,FosseE,SundetK,TennoeBetal.Comparisonofcerebralembolizationduringoff-pumpandon-pumpcoronaryarterybypasssurgery.AnnThoracSurg2003;76(3):765-770.

54.WattersMP,CohenAM,MonkCR,AngeliniGD,RyderIG.ReducedcerebralembolicsignalsinbeatingheartcoronarysurgerydetectedbytranscranialDopplerultrasound.BrJAnaesth2000;84(5):629-631.


55. Diegeler A, Hirsch R, Schneider F, Schilling LO, Falk V, Rauch T et al. Neuromonitoring andneurocognitiveoutcomeinoff-pumpversusconventionalcoronarybypassoperation.AnnThoracSurg2000;69(4):1162-1166.

56. Butler J, Parker D, Pillai R, Westaby S, Shale DJ, Rocker GM. Effect of cardiopulmonary bypass onsystemic release of neutrophil elastase and tumor necrosis factor. J Thorac Cardiovasc Surg 1993;105(1):25-30.

57.ArchboldRA,CurzenNP.Off-pumpcoronaryarterybypassgraftsurgery:theincidenceofpostoperativeatrialfibrillation.Heart2003;89(10):1134-1137.

58.JansenNJ,vanOeverenW,vanVlietM,StoutenbeekCP,EysmanL,WildevuurCR.Theroleofdifferenttypesofcorticosteroidsontheinflammatorymediatorsincardiopulmonarybypass.EurJCardiothoracSurg1991;5(4):211-217.

59.vanDijkD,MoonsKG,KeizerAM,JansenEW,HijmanR,DiephuisJCetal.Associationbetweenearlyandthreemonthcognitiveoutcomeafteroff-pumpandon-pumpcoronarybypasssurgery.Heart2004;90(4):431-434.

60.NewmanMF,KirchnerJL,Phillips-ButeB,GaverV,GrocottH,JonesRHetal.Longitudinalassessmentofneurocognitivefunctionaftercoronary-arterybypasssurgery.NEnglJMed2001;344(6):395-402.

61.MathewJP,ParksR,SavinoJS,FriedmanAS,KochC,ManganoDTetal.Atrialfibrillationfollowingcoronaryarterybypassgraftsurgery:predictors,outcomes,andresourceutilization.MultiCenterStudyofPerioperativeIschemiaResearchGroup.JAMA1996;276(4):300-306.

62.ArankiSF,ShawDP,AdamsDH,RizzoRJ,CouperGS,VanderVlietMetal.Predictorsofatrialfibrillationafter coronary artery surgery. Current trends and impact on hospital resources. Circulation 1996;94(3):390-397.

63.VedinJ,AntovicA,EricssonA,VaageJ.Hemostasisinoff-pumpcomparedtoon-pumpcoronaryarterybypassgrafting:aprospective,randomizedstudy.AnnThoracSurg2005;80(2):586-593.

64.ParolariA,MussoniL,FrigerioM,NaliatoM,AlamanniF,GalantiAetal. Increasedprothromboticstatelastingaslongasonemonthafteron-pumpandoff-pumpcoronarysurgery.JThoracCardiovascSurg2005;130(2):303-308.

65.AscioneR,LloydCT,UnderwoodMJ,LottoAA,PitsisAA,AngeliniGD.Inflammatoryresponseaftercoronaryrevascularizationwithorwithoutcardiopulmonarybypass.AnnThoracSurg2000;69(4):1198-1204.

66.BiglioliP,CannataA,AlamanniF,NaliatoM,PorquedduM,ZanobiniMetal.Biologicaleffectsofoff-pumpvs.on-pumpcoronaryarterysurgery:focusoninflammation,hemostasisandoxidativestress.EurJCardiothoracSurg2003;24(2):260-269.

67. Matata BM, Sosnowski AW, Galinanes M. Off-pump bypass graft operation significantly reducesoxidativestressandinflammation.AnnThoracSurg2000;69(3):785-791.

References 125

68.D’AnconaG,DoniasHW,KaramanoukianRL,BergslandJ,KaramanoukianHL.OPCABtherapysurvey:off-pumpclopidogrel,aspirinorboththerapysurvey.HeartSurgForum2001;4(4):354-358.

69.SteinhublSR.Antiplateletagentsincardiology:thechoiceoftherapy.AnnThoracSurg2000;70(2Suppl):S3-S8.

70. Schomig A, Neumann FJ, Kastrati A, Schuhlen H, Blasini R, Hadamitzky M et al. A randomizedcomparisonofantiplateletandanticoagulanttherapyaftertheplacementofcoronary-arterystents.NEnglJMed1996;334(17):1084-1089.

71.BhattDL,ChewDP,HirschAT,RinglebPA,HackeW,TopolEJ.Superiorityofclopidogrelversusaspirininpatientswithpriorcardiacsurgery.Circulation2001;103(3):363-368.

72. Gaudino M, Andreotti F, Zamparelli R, Di Castelnuovo A, Nasso G, Burzotta F et al. The -174G/Cinterleukin-6 polymorphism influences postoperative interleukin-6 levels and postoperative atrialfibrillation. Is atrial fibrillation an inflammatory complication? Circulation 2003; 108 Suppl 1:II195-II199.

Summarynederlandse samenvattingList of abbreviationsdankwoordCurriculum VitaePublications

128

SuMMAry

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) is still

associatedwithsignif icantmorbidity.ThishasbeenlargelyattributedtotheuseoftheCPB

system,asitinvolvesactivationofahemostaticandinflammatoryresponse,nonpulsatile

flow and possible embolization of air or debris, which may all contribute to CPB-related

organdysfunction.Thesearchforwaystoreducecomplicationrateshasledtoarenewed

interest in bypass surgery on the beating heart. The invention of cardiac wall stabilizers

such as the Octopus Stabilizer made it possible to immobilize and present all the sides

of the beating heart, thus facilitating bypass surgery without the use of CPB (off-pump

CABG).However,althoughavoidingCPBduringcoronaryrevascularizationhassignif icantly

decreasedmorbidity insomegroupsofpatients,off-pumpsurgerycomplicationratesare

stillsubstantial.ThismaysuggestthatotherfactorsthantheCPB,suchastheglobalsurgical

traumaandthesubsequentialhemostaticandinflammatoryresponsemaybeasimportant,

orevenmoreinthepathofysiologyofpostoperativemorbidityaftercardiacsurgery.

Theaimofthisthesiswastostudyactivationofhemostasisandinflammationinpatients

undergoingCABGwithorwithoutCPBandtherelationshipofcoagulationandinflammation

withclinicaloutcome.

Chapter 2 gives a short overview of normal hemostasis and pathophysiological effects of

CPBonthecoagulationsystem.Inaddition,strategiestoattenuatehemostaticactivation

duringCPBandactivationofhemostasisinoff-pumpcardiacsurgeryarealsodiscussed.

In chapter 3 of this thesis, postoperative activation of hemostasis after the two types

of surgery is compared. Two groups of consecutive patients participating in the Octopus

StudywererandomlyallocatedtoundergoCABGwith(n=20)orwithoutCPB(n=20).Platelet

numberandplasmaconcentrationsofP-selectin,prothrombinfragments1.2(F1.2),soluble

f ibrin,D-dimersandvonWillebrandFactor(VWF,asamarkerofendothelialcellactivation)

weremeasuredandcorrectedforhemodilution.Comparedtotheon-pumpCABGgroup,F1.2

andD-dimerlevelsweresignif icantlylowerinpatientshavingCABGsurgeryperformedoff-

pump.IntheCPBgroup,F1.2andD-dimerpeakedintheimmediatepostoperativeperiodto

4-5timesbaselinevalues,andremainedelevateduptoday4,whileintheoff-pumpgroup

F1.2 and D-dimer levels rose more gradually and were highest on day 4. In both groups,

VWFconcentrationswereelevatedmorethan3timesbaselinevaluesuptoday4.Despite

heparinization,CABGsurgerywithCPBwasassociatedwithexcessivethrombingeneration

andf ibrinolyticactivityimmediatelypostoperatively.Theoff-pumpgroupdemonstrateda

delayedpostoperativeresponsethatbecameequalinmagnitudetotheCPBinthelater(20

and96hours)postoperativeperiod.

Clinical signif icance of the hypercoagulable state after off-pump surgery is assessed in

chapter 4. Several studies have shown that cognitive decline also occurs after off-pump

Summary

CABG, suggesting that other factors than the use of CPB contribute to cognitive decline.

We hypothesized that a hypercoagulable state after off-pump surgery may contribute to

cognitive decline. In a sample of 60 consecutive patients undergoing off-pump CABG, we

studied the association between postoperative activation of hemostasis, as reflected by

D-dimers and F1.2 and cognitive outcome at the 4th day, 3 and 12 months after surgery.

D-dimerandF1.2levelsattwohoursaftertheoff-pumpprocedurewerestronglyassociated

with cognitive decline on postoperative day 4. Also in a multivariate logistic regression

model, postoperative D-dimer levels were a strong predictor of early cognitive decline.

No association was found between postoperative activation of hemostasis and cognitive

outcome after 3 and 12 months. Our data indicate that early postoperative D-dimer and

F1.2 levels associated with early cognitive outcome after off-pump CABG. Activation of

hemostasismaythereforecontributetocognitivedeclineinoff-pumpsurgery.

Inchapter5,wecomparedactivityofvonWillebrandFactor(VWF),aproteinwhichplaysan

essentialroleinprimaryhemostasis,directlyafterbothtypesofsurgery.Highshearforces

caninducestructuralchangesintheshapeoftheVWFmolecule,makingitmoresensitive

forADAMTS-13,aspecif icVWFprotease.Thisleadstoproteolysisofthehighest–molecular-

weight multimers, which are the most effective in platelet-mediated hemostasis under

conditionsofhighshearstress.As theuseofCPB isaccompaniedwithhighshear forces,

thiscouldtherefore leadtodiminishedVWFactivity.Weenrolled60patientsundergoing

CABG surgery with and without CPB (30 each group). ADAMTS-13 activity, VWF antigen

(VWF:Ag) and propeptide levels were measured directly before and after the procedure.

VWF activity was determined using both the ristocetin cofactor activity (VWF:Rcof) and

collagenbinding(VWF:CB)assays.VWF:RcofandVWF:CB,bothcorrectedforVWF:Ag,were

signif icantlyincreasedaftertheprocedureintheoff-pumpgroup,butnotintheCPBgroup.

Postoperative VWF:Ag and VWF-propeptide levels signif icantly increased in both groups.

ADAMTS-13activityincreasedafterbothtypesofsurgeryaftercorrectionforhemodilution.

Postoperative VWF:Rcof levels correlated with postoperative D-dimer levels and were

associatedwithearlycognitivedeclineintheoff-pumpgroup.OurdataindicatethatVWF

activitywasincreasedafteroff-pumpCABG,butnotafterCABGwithCPB.Sincereleaseof

VWFwascomparableinbothgroups,shear–stressinducedproteolysisduetotheuseofCPB

mightberesponsibleforthedecreasedVWFactivity.Thismechanismleadstoarelatively

decreased hypercoagulability after CABG with CPB. In addition, one may ask whether

perioperativeanticoagulationstrategiesduringoff-pumpsurgeryshouldbealtered.

Thoracicepiduralanalgesia(TEA)duringcardiacsurgeryhasmanyadvantages.TEAimproves

hemodynamicstability,reducesmyocardialoxygenconsumption,potentiallydecreasesthe

incidenceofintra-andpostoperativemyocardialischemiaandimprovesqualityofanalgesia

andpostoperative pulmonary function.However, theuseofTEAduringon-pumpCABGis

limited because of the perceived risk of epidural hematoma formation secondary to full

129

130 Summary

heparinizationduringCPB.InOPCABsurgery,TEAismoreacceptedasfullheparinizationis

notnecessaryforthesurgicalprocedure.IntheOctopusStudy,themajorityoftheOPCAB

patientsreceivedTEAincombinationwithgeneralanesthesia.Postoperativeactivationof

hemostasismaybeaffectedbytheintraoperativeuseofTEA.Theuseofepiduralanalgesia

isassociatedwithasignif icantreductionintheincidenceofpostoperativethromboembolic

complicationssuchasdeepvenousthrombosisandpulmonaryemboliandsimilarreductions

areobtainedwhenlocalanesthetics(LA),areinfusedIV.Themechanismsforthiseffectare

still unknown but inflammatory mediators – released in response to surgical trauma and

inducingthrombosisandvasoconstriction–arelikelytobepivotal.Oneofthesemediators

affected by TEA could be thromboxane A2 (TXA2), a potent platelet aggregator and which

is usually increased after surgery. From experimental studies it is known that LA inhibit

TXA2.Toverifyesperimentalresults,weconductedatrialwherewestudiedtheeffectsof

clinicallyusedLA(lidocaine,ropivacaine,andbupivacaine)onTXA2-inducedearlyplatelet

aggregation (1–5 s) by using quenched-flow and optical aggregometry (chapter 6). Our

f indingsdemonstratedthattheLAtestedseemtohaveonlyalimitedabilitytoinhibitTXA2-

inducedplateletaggregationassessedatearlytimes(1–5s).Therefore,theclinicaleffects

ofLAonthrombiformationareunlikelytobeexplainedbythismanneralone.AtlargeLA

concentrations, moderate effects were obtained. Prolonged incubation with LA did not

signif icantly increase effectiveness, and the lack of an effect could not be explained by

generationofsecondarymediators.Theresultswereindependentoftheanestheticstudied.

LocalanestheticeffectsonTXA2-inducedearlyplateletaggregation(1–5s)areunlikelyto

playamajorroleintheclinicallyobservedantithromboticeffectsoflocalanesthetics.

Activation of the complement system after CABG surgery involves CRP. This inflammatory

responseisrelatedtobaselineCRPlevelsandassociatedwithpostoperativearrhythmia,in

particularatrialf ibrillation(AF).Inchapter7,weinvestigatedwhetherbaselineCRPlevels

areariskindicatorfortheoccurrenceofAFandwhetherthisphenomenonisCPB-dependent.

CRPwasmeasuredinperioperativebloodsamplesofpatientsoftheOctopus-study(CABG

surgerywith(n=73)orwithoutCPB(n=79)).BaselineCRPwasdichotomizedintoalowand

ahighbaselinegroup,usingacut-offof3.0mg/L.AfterCABGwithCPB11of53patients

(21%)withlowpreoperativeCRPlevelsdevelopedAF,versus11of20patients(55%)with

highbaselineCRPlevels.Intheoff-pumpgroupAFoccurredin4of52patients(8%)whohad

lowbaselineCRPlevels,versusin8of27patients(30%)withhighpreoperativeCRPlevels.

Afteradjustingforage,theoddsratiowas4.6withCPB,3.7intheoff-pumpgroupand3.3

forbothgroupstogether.ContinuousbaselineCRPwasanindependentpredictorforAFina

multivariatelogisticregressionmodel.PatientswithhighbaselineCRPlevelsareathigher

riskofdevelopingpostoperativeAFinbothon-pumpandoff-pumpsurgery.

Finally,chapter8discussestheimplicationsofourf indingsinawidercontext,togetherwith

suggestionsforfutureresearch.First,thehypercoagulablestateafteroff-pumpsurgeryis

131

discussedtogetherwithpossibleevidencelinkingtheearlypostoperativehypercoagulable

statetothromboemboliceventsandpooroutcome.Nexttoourf indingsthatpostoperative

activation of hemostasis may play a role in the pathophysiology of cognitive decline, it

may also affect long-term graft patency. Second, explanations are forwarded why we

couldnotdemonstrateanassociationbetweenCPB-inducedactivationofhemostasisand

CRPresponseontheonehandandclinicaloutcomeparametersontheotherhand.Special

attentionisgiventotheabsenceofanassociationbetweenactivationofhemostasisand

cognitivedeclineasthiscouldbewelldemonstratedafteroff-pumpsurgery.Otherpossible

pathophysiologicmechanismsofthedevelopmentofcognitivedeclineafterconventional

CABGsurgeryarethereforeoutlined.Futurestudiesshouldbefocussedonevaluatingthe

relationshipbetweenclinicaloutcomeandpostoperativeactivationofhemostasisafteron-

andoff-pumpCABG.Withnodoubt,thisrepresentsaverycomplexf ieldof investigation,

which needs a large number of patients, strict protocols and imposes heavy workload

because of numerous blood sampling. In addition, more research is needed to evaluate

theoptimalpharmalogicalmanagementofthehypercoagulablestateandpossiblerelated

complicationsafteroff-pumpcoronaryrevascularization.

Itisconcludedthatoff-pumpCABGisassociatedwithpostoperativeactivationofhemostasis

thatbecomesequalinmagnitudetoCABGwithCPBinthelater(20-96hours)postoperative

period is found. This hypercoagulable state after off-pump surgery is intensif ied by a

relatively increased von Willebrand Factor activity. Early postoperative activation of

hemostasisisassociatedwiththeincidenceofearlypostoperativecognitivedeclineafter

off-pumpCABG.BaselineCRPlevels,areariskindicatorfortheincidenceofpostoperative

atrialf ibrillationafteron-pumpandoff-pumpCABG.

132 Nederlandsesamenvatting

nederLAndSe SAMenVAttInG

Coronairebypasschirurgie(CABG)metgebruikvaneenhart-longmachine(dezogenaamde

on-pump CABG) gaat gepaard met een nog steeds aanzienlijk aantal postoperatieve com-

plicaties (3-5%), zoals myocardischemie, nierfunctiestoornissen en cerebrovasculaire in-

cidenten. Dit wordt grotendeels geweten aan het gebruik van de hart-longmachine zelf,

aangezien dit gepaard gaat met activatie van stolling en een ontstekingsrespons, niet-

pulsatieleflowenmogelijkeembolisatievanluchtofdebris,welkeallebijkunnendragen

aanhart-longmachine-gerelateerdeorgaanschade.Hetzoekennaarmanierenomdecom-

plicatiesteverminderenheeftgeleidtoteenhernieuwdeaandachtvoorbypasschirurgieop

hetkloppendehart.Deontwikkelingvantechniekendiehetmogelijkmakenomallezijden

vanhetkloppendehartteimmobiliserenentepresenteren,zoalsbijvoorbeelddeOctopus

Stabilizer,makenzobypasschirurgiezonderhart-longmachinemogelijk(off-pumpCABG).

Echter, hoewel het weglaten van de hart-longmachine tijdens coronaire revascularisatie

demorbiditeit insommigegroepenpatiëntensignif icantverlaagt,komenernaoff-pump

chirurgieooknogsteedscomplicatiesvoor.Dit zoukunnensuggererendatandere facto-

rendandehart-longmachine,zoalshetchirurgischetraumaendedaaropvolgendehemo-

statischeeninflammatoirereactienetzobelangrijk,ofmisschienzelfsbelangrijkerzijnbij

hetontstaanvanpostoperatievecomplicatiesnahartchirurgie.

Het primaire doel van het onderzoek was om activatie van hemostase en ontsteking te

bestuderen in patiënten die een CABG ondergaan mét of zonder hart-longmachine en de

relatievanstollingenontstekingmetklinischeeindpuntenteonderzoeken.

Hoofdstuk 2 geeft een kort overzicht over normale hemostase en de pathofysiologische

effecten van de hart-longmachine op het stollingssysteem. Daarnaast worden er ook een

aantal strategieën toegelicht, die toegepast worden om deze activatie te beperken. Ook

wordtdestollingsactivatienaoff-pumpCABGbesproken.

Inhoofdstuk3vanditproefschriftwordtdepostoperatieveactivatievanhemostasetussen

de twee typeschirurgievergeleken.Tweegroepenvanopeenvolgendepatiënten,deelne-

mendaandeOctopusStudiewerdendoorloting(randomisatie)toegewezenaanCABGmet

(n=20)ofzonderhart-longmachine(n=20).Trombocytenaantalenplasmaconcentratiesvan

P-selectine,protrombinefragmenten1.2(F1.2),oplosbaarf ibrine,D-dimerenenvonWil-

lebrandFactor(VWF,alsmaatvoorendotheelcelactivatie)werdengemetenengecorrigeerd

voorverdunningseffecten.Vergelekenmetdeon-pumpCABGgroep,warendeF1.2enD-di-

meerspiegelssignif icantlagerindeoff-pumpCABGpatiënten.Indeon-pumpgroeppiek-

tenF1.2enD-dimeerspiegelstot4-5maaldeuitgangswaardeindedirectpostoperatieve

periodeenblevenverhoogdtotaandag4, terwijl indeoff-pumpgroepF1.2enD-dimeer

spiegelsmeergeleidelijkstegentotvergelijkbarewaardesals indeon-pumpgroepenop

zijnhoogstwarenopdag4.InbeidegroepenwarenconcentratiesvanVWFtotmeerdan3

133

maalverhoogdtotaandag4.OndanksheparinisatiegingCABGmethart-longmachinedus

gepaardmetexcessievetrombinegeneratieenf ibrinolytischeactiviteitdirectpostopera-

tief. De off-pump groep vertoonde een vertraagde postoperatieve respons die in omvang

gelijkwerdaandievandeon-pumpgroepindelaterepostoperatieveperiode(20-96uur).

Deklinischebetekenisvandeverhoogdestollingsneigingnaoff-pumpchirurgiewordtvast-

gesteldinhoofdstuk4.Verscheidenestudieshebbenaangetoonddatcognitieveachteruit-

gangookplaatsvindtnaoff-pumpCABG,suggererenddatanderefactorendanhetgebruik

van de hart-longmachine bijdragen aan het ontstaan van cognitieve achteruitgang. We

verondersteldendatdehypercoagulabele toestandnaoff-pumpCABGookbij zoukunnen

dragen aan cognitieve achteruitgang. In 60 opeenvolgende patiënten die off-pump CABG

ondergingen, bestudeerden we de associatie tussen postoperatieve activatie van hemo-

stase, weergeven door D-dimeer en F1.2 spiegels, en cognitieve achteruitgang op de 4e

postoperatievedag,en3en12maandennadeoperatie.D-dimeerenF1.2spiegelsgemeten

2uurnadeoff-pumpprocedurewarensterkgeassocieerdmetcognitieveachteruitgangop

de4epostoperatievedag.Ookineenmultivariate logistischregressiemodelwarenpost-

operatieveD-dimeerspiegelseensterkevoorspellervoorvroegecognitieveachteruitgang.

Erwerdgeenassociatiegevondentussenpostoperatieveactivatievanhemostaseencogni-

tieveachteruitgangna3en12maanden.Onzeresultatengevenaandatvroegepostopera-

tieveD-dimeerenF1.2spiegelsgeassocieerdzijnmetvroegecognitieveachteruitgangna

off-pumpCABG.Activatievanhemostasezoudusbijkunnendragenaanhetontstaanvan

cognitieveachteruitgangnaoff-pumpchirurgie.

In hoofdstuk 5 hebben we de activiteit van VWF, een eiwit dat een belangrijke rol speelt

bijdeprimairehemostase,directnabeidetypeschirurgievergeleken.Hoge“shearforces”

(wrijvingskrachten op de vaatwand ten gevolge van de bloedstroom) kunnen structurele

veranderingen indevormvanhetVWFmolecuul induceren,enhetgevoeligermakenvoor

ADAMTS-13,eenspecif iekVWF-protease.Ditleidttotdeproteolyse(afbraak)vandehoogst-

moleculaire-gewicht-multimeren van VWF, die het meest effectief zijn in bloedplaatjes-

gemedieerdehemostaseonderomstandighedenmethogeshear-stress.Aangezienhetge-

bruikvandehart-longmachinegepaardgaatmethogeshearforces,zoudittotverminderde

VWF activiteit kunnen leiden. In deze studie includeerden we 60 patiënten die een CABG

met of zonder hart-longmachine ondergingen (30 per groep). ADAMTS-13 activiteit, VWF-

antigen(VWF:Ag)en-propeptidespiegelswerdendirectvoorennadeproceduregemeten.

VWF activiteit werd bepaald door zowel de ristocetine cofactor activiteit (VWF:Rcof) as-

say als de collageen-binding (VWF:CB) assay. VWF activiteit was signif icant verhoogd na

de ingreep in de off-pump groep, maar niet in de on-pump groep. Postoperatieve VWF:Ag

enVWFpropeptidespiegelswarensignif icantverhoogdinbeidegroepen.Deactiviteitvan

ADAMTS-13steegnabeidetypeschirurgienadatgecorrigeerdwasvoorhemodilutie.Post-

operatieveVWF:RcofspiegelscorrelleerdenmetpostoperatieveD-dimeerspiegelsenwaren


geassocieerdmetvroegecognitieveachteruitgangindeoff-pumpgroep.Onzedatageven

aandatVWFactiviteitisverhoogdnaoff-pumpCABG,maarnietnaCABGmetdehart-long-

machine.AangeziendeuitscheidingvanVWFvergelijkbaarisinbeidegroepen,zoushear-

stressgeïnduceerdeproteolysedoorhetgebruikvandehart-longmachineverantwoordelijk

kunnenzijnvoordeverlaagdeVWFactiviteit.Ditmechanismeleidtdustoteenverminderde

hypercoagulabiliteitnaCABGmethart-longmachine.Tevenskanmenzichafvragenofhet

huidigeanti-stollingsbeleidbijoff-pumpCABGvoldoendeaggressiefis.

Thoracale epidurale analgesie (TEA) tijdens hartchirurgie heeft veel voordelen. Het ver-

betert hemodynamische stabiliteit, vermindert zuurstofconsumptie van de hartspier, re-

duceertmogelijk intra-enpostoperatievemyocardischemieenverbetertdekwaliteitvan

pijnbestrijdingenpostoperatievelongfunctie.Echter,hetgebruikvaneenTEAtijdenson-

pumpCABGisbeperktdoorhetrisicoopeenepiduraalhematoomalsgevolgvanvolledige

heparinisatie bij het gebruik van de hart-longmachine. Bij off-pump chirurgie wordt TEA

meer geaccepteerd, aangezien volledige heparinisatie bij dit type chirurgie niet noodza-

kelijk is. IndeOctopusStudieheefteenmeerderheidvandeoff-pumppatiënteneenTEA

gekregen en de postoperatieve activatie van hemostase kan hierdoor beïnvloed zijn. Het

gebruik van een TEA is geassocieerd met een signif icante reductie in de incidentie van

postoperatievetromboembolischecomplicatieszoalsveneuzetromboseenlongembolieën

envergelijkbarereductieszijnwaargenomenwanneerlokaalanesthetica(LA)intraveneus

wordentoegediend.Demechanismenhiervoorzijnnogonbekend.Eenvandemediatoren

zoutromboxaanA2(TXA2)kunnenzijn,eenkrachtigebloedplaatjesaggregatorenwaarvan

spiegelsverhoogdzijnnachirurgie.Inhoofdstuk6hebbenwedeeffectenvanklinischge-

bruikteLA(lidocaine,ropivacaineenbupivacaine)onderzochtopTXA2-geïnduceerdevroege

plaatjesaggregatie(1-5s)dooreenquenched–flowenoptischeaggregometertegebruiken.

OnzebevindingentonenaandatdegetesteLAslechtseenbeperktemogelijkheidhebben

omdeTXA2-geïnduceerdevroegeplaatjesaggregatieteremmen.KlinischeeffectenvanLA

ophetvormenvantrombiwordenduswaarschijnlijknietalleenopdezemanierverklaard.

BijhogeLAconcentratieswerdengematigdeeffectengevonden.Verlengdeincubatiemet

LA verhoogde de effectiviteit niet signif icant en de afwezigheid van een effect kon niet

verklaardwordendoordeaanmaakvansecundairemediatoren.Deresultatenwarenonaf-

hankelijkvanhetbestudeerdeanestheticum.EffectenvanLAopTXA2-geïnduceerdevroege

plaatjesaggregatie(1-5s)lijkendusgeengroterolspelenbijhetklinischwaargenomenan-

titrombotischeffectvanLA.

C-reactiveprotein(CRP)isbetrokkenbijdeactivatievanhetcomplementsysteemnaCABG.

Deze ontstekingsrespons is gerelateerd aan preoperatieve CRP spiegels en geassocieerd

met postoperatieve hartritmestoornissen, in het bijzonder boezem- of atriumfibrilleren

(AF).Inhoofdstuk7hebbenweonderzochtofpreoperatieveCRPwaardeneenrisicoindica-

torzijnvoorhetoptredenvanAFenofditfenomeenafhankelijkisvanhetgebruikvande

135

hart-longmachine.CRPwerdgemeten inperioperatievebloedmonstersvanpatiëntenvan

deOctopusStudie(CABGmet(n=73)ofzonderhart-longmachine(n=79)).PreoperatiefCRP

werdgedichotomiseerdineenlageeneenhogebasis-CRPgroep,waarbijeengrenswaarde

van3.0mg/lwerdgehanteerd.NaCABGmethart-longmachineontwikkelden11vande53

patiënten(21%)meteen laagbasis-CRPAF, tenopzichtevan11vande20patiëntenmet

eenhoogbasis-CRP(55%).Indeoff-pumpgroeptradAFin4vande52patiënten(8%)met

een laagbasis-CRPop, tenopzichtevan8vande27patiënten(30%)methogebasis-CRP

waarden. Na correctie voor leeftijd was de odds ratio 4.6 in de hart-longmachine groep,

3.7indeoff-pumpgroep,en3.3voorbeidegroepensamen.Ookalscontinuevariabelewas

hetuitgangs-CRPeenonafhankelijkevoorspellervoorAFineenmultivariatelogistischre-

gressiemodel.Concluderendhebbenpatiëntenmethogepre-operatieveCRPwaarden,als

uiting van chronische subklinische inflammatie, een hoger risico op het ontwikkelen van

postoperatiefAFnazowelon-pumpalsoff-pumpCABG.

Tenslottebespreekthoofdstuk8deimplicatiesvanonzeresultatenineenbrederecontext,

samen met de beperkingen van de studies en suggesties voor toekomstig onderzoek. Ten

eerste wordt de hypercoagulabele toestand na off-pump CABG belicht; er zijn aanwijzin-

gen dat deze hypercoagulabele toestand leidt tot meer tromboembolische complicaties.

Naast onze bevindingen dat postoperatieve activatie van hemostase een rol kan spelen

in de pathofysiologie van cognitieve achteruitgang, kan het ook een effect hebben op

de lange termijn doorgankelijkheid van de geplaatste bypasses op het hart. Ondanks een

meer uitgesproken activatie van de hemostase na CABG met hart-longmachine worden er

geen associaties aangetoond tussen deze activatie van hemostase enerzijds en klinische

uitkomsten anderzijds. Hiervoor worden een aantal verklaringen gegeven. Opmerkelijk is

deafwezigheidvaneenverbandtussenactivatievanhemostaseenpostoperatievecogni-

tieveachteruitgangnaCABGmethart-longmachine,aangeziendezewelkonwordenaan-

getoondnaoff-pumpchirurgie.Ditsuggereertdatermogelijkanderepathofysiologische

mechanismenverantwoordelijkzijnvoorcognitieveachteruitgangnaconventioneleCABG.

Toekomstigestudiesmoetenzich richtenopde relatie tussenhardeklinischeuitkomsten

enpostoperatieveactivatievanhemostasenaon-enoff-pumpCABG.Hetiszekerdatvoor

dittypeonderzoekstrikteprotocolleringengrotepatiëntenaantallenvereistzijn.Doorde

talrijkeafnamesvanbloedmonstersenspecif iekemetingeningespecialiseerdelaboratoria

isdittypeonderzoekookduur.Daarnaastisermeeronderzoeknodigomtebepalenwatde

optimale farmacologische behandeling is van de hypercoagulabele toestand na off-pump

CABGomhieraanmogelijkgerelateerdecomplicatiestevoorkomen.Hetvroegpostopera-

tiefstartenvanaspirinezoalsdoorManganowordtgesuggereerdzoueenvandezeopties

kunnenzijn.


Concluderendisernaoff-pumpCABGpostoperatieveactivatievanhemostasedieinomvang

gelijk wordt aan die van on-pump CABG in de latere postoperatieve periode (20-96 uur).

Deze hypercoagulabele toestand na off-pump chirurgie wordt versterkt door een relatief

verhoogdevonWillebrandFactoractiviteitpostoperatief.Vroegepostoperatieveactivatie

vanhemostaseisgeassocieerdmethetoptredenvanvroegecognitieveschadenaoff-pump

CABG.PreoperatieveCRPwaardenzijneenrisicoindicatorvoorhetoptredenvanatriumfi-

brillerennazowelon-pumpalsoff-pumpchirurgie.

137Listofabbreviations

LISt oF ABBreVIAtIonS

ACD acidcitratedextrose

ACT activatedclottingtime

ADAMTS-13 adisintegrin-likeandmetalloproteasewiththrombospondintype1motif

AF atrialf ibrillation

APC activatedproteinC

AT-III antithrombinIII

CABG coronaryarterybypassgrafting

CI confidenceinterval

CPB cardiopulmonarybypass

CRP C-reactiveprotein

EACA e-aminocaproicacid

ELISA enzyme-linkedimmunosorbentassay

F1.2 prothrombinfragment1.2

FRET fluorescenceresonanceenergytransfer

GP glycoprotein

IgG immunoglobinG

IQR interquartilerange

LA localanesthetics

OPCAB off-pumpcoronaryarterybypassgrafting

OR oddsratio

PAI plasminactivatorinhibitor

PODVT postoperativedeepvenousthrombosis

PRP platelet-richplasma

SD standarddeviation

sP-selectin solubleP-selectin

TA tranexaminicacid

TAFI thrombin-activablef ibrinolyisinhibitor

TEA thoracicepiduralanalgesia

TF tissuefactor

TFPI tissuefactorpathwayinhibitor

t-PA tissueplasminogenactivator

TXA2 thromboxaneA2

u-PA urinary-typeplasminogenactivator

VWF vonWillebrandFactor

VWF:Ag vonWillebrandFactorantigen

VWF:CB vonWillebrandFactorcollagenbindingactivity

VWF:Rcof vonWillebrandFactorristocetincofactoractivity

138

dAnKWoord

Een van de grote voordelen van wetenschappelijk onderzoek is boven je eigen vakgebied

uit stijgen en door het kijken in andermans keuken te leren ook op een andere manier

problemen te benaderen. Bovendien leg je veel waardevolle contacten met mensen uit

allerlei disciplines, waarvan sommige zelfs uitmonden in innige vriendschappen. De

disciplines thoraxchirugie, cardiologie, anesthesiologie, epidemiologie en psychologie

warenalverenigdindeorigineleOctopusStudie,endoormiddelvanditproefschriftzijnde

hematologieenklinischechemiedaaraantoegevoegd.Hetdiscussiërenmetanderenover

meer of minder triviale knelpunten in het onderzoek of juist heel andere zaken zijn een

enormeverrijkinggeweestenikwildanookiedereenbedankendieopeenofanderemanier

eenbijdrageheeftgeleverdaanditproefschrift.

Allereerstmijnpromotor,prof.dr.C.J.Kalkman.BesteCor,vanafhetbeginhebjeaangegeven

dat jij je als kritische leek met mijn onderzoek bezig wilde houden. De inhoudelijke

diepgang moest vooral van de co-promotoren komen. Toch zijn jouw kritische vragen en

jouwcommentaaropalmijnartikelenvangrotewaardegeweest.Jijhebtmijalsgeenander

geleerdhoe jedingenwetenschappelijkmoetverwoordenenhelderopkuntschrijven.En

hoewel jehetooksteedsdrukkerkreeg,zijn jebelangstellingenenthousiasmevoormijn

onderzoeknietafgenomenenvoormijeenbronvaninspiratiegebleven.Hopelijkkunnen

weintoekomstnogverdersamenwerken.

Mijn co-promotor dr. R.Fijnheer. Beste Rob, toen je nog fulltime in het UMC werkte, kon

ik altijd met allerlei problemen bij je binnenlopen en jij wist altijd wel iemand te vinden

die ze kon helpen oplossen. Toen je naar het Jeroen Bosch Medisch Centrum overging,

werd dat wel lastiger, maar met alleen de vrijdagen konden we het ook prima redden.

Doorjelaagdrempeligheidenjehumorhebikergvanonzesamenwerkinggenoten.Ikheb

bewondering voor je, hoe je, ondanks een lichte chaos, toch wetenschap, werken in een

perifeerziekenhuis,eendrukgezineneendruksociaallevenkuntcombineren.

Mijnandereco-promotor,dr.A.P.Nierich.BesteArno,jeervaringalscardio-anesthesioloog

kwam goed van pas om onze bevindingen in het lab beter naar de kliniek te vertalen, en

andersom.Doordat je inZwollezat,wasafsprekennietaltijdeenvoudig,maarviae-mail,

telefoonenafentoeeentreinreisjezijnwetocheenheeleindgekomen.Zonderjouwasook

def inancieringvoorditonderzoekdoorMedtronicnooittotstandgekomen.Hetverbaast

medanooknietdatjeeenprachtigeonderzoeksinfrastructuurinZwollevandegrondhebt

gekregen.Wieweetliggenerindetoekomstnogmeergemeenschappelijkeprojecteninhet

verschiet.

Dankwoord

Mijnopleider,prof.dr.J.T.A.Knape.Ikherinnermenoggoeddatikunamijnkeuze-co-schap

eenopensollicitatiebriefgestuurdhad,netnadatallesollicitatierondesalgeweestwaren.

Eendaglaterstonduopmijnantwoordapparaatommetezeggendatiktochmeteennamijn

artsexamenalsAGNIOmochtbeginnen.Ikhoopdatunogsteedsachterdiekeuzestaat.Uw

betrokkenheidenbelangstellingvoormijnonderzoekmaarookvooranderelife-eventsheb

ikaltijdalszeerprettigervaren.

Diederik van Dijk. Zonder jouw Octopus Studie en analyses had ik in de eerste plaats

geen bloedmonsters gehad om door te meten en waren mijn bevindingen slechts beperkt

tot laboratoriumwaardes. Talrijke keren heb ik je lastig moeten vallen met de vraag of je

niettochnogbepaaldedataofanalysesvoormehad.Ikhebnooitvanjegehoorddathet

even niet uitkwam. Integendeel, ik kreeg altijd het idee dat het vanzelfsprekend was dat

je me zou helpen, al zal dat zeker niet altijd het geval geweest zijn. Ook van je heldere

enogenschijnlijkeenvoudigemaniervanformuleren,hebikontzettendveelgeleerd.Dank

hiervoor.

Hendrik Nathoe, samen met Diederik heb jij de Octopus Studie gerund. Jij hebt daar een

prachtig proefschrift mee voortgebracht en de laboratoriumbepalingen die je van me

gekregenhebtdaarnieteensnodigvoorgehad.Ikheb jouookregelmatigbenaderdvoor

klinischedata,waarvoorikjezeererkentelijkben.Misschiendatonzesamenwerkinginde

toekomstooknogzijnvruchtenafwerpt.

AlleartsendiedeOctopusStudiemogelijkgemaakthebbenendanmetnamedr.P.P.Th.de

Jaegere,JanDiephuis,JaapLahpor,ErikJansen.Ookalleartsenenverpleegkundigendie

betrokkenzijngeweestbijdevelebloedafnamesbenikmijndankverschuldigd.

Als vanzelfsprekend dank ik ook alle deelnemers aan de Octopus Studie en dan met name

diegenenwaarbijdebloedmonsterszijnafgenomenenookingrotemeerderheidtrouwde

velefollow-uponderzoekenhebbenondergaan.

Harry Wisse en Marcel Bruens. Dankzij jullie zijn de bloedafnames van alle patienten en

opslaghiervaneenergoverzichtelijkgeheelgebleven.

ProfessorKeesBorst.AlsuitvindervandeOctopusTissueStabilizerwasualsmede-auteur

betrokkenbijmijneersteartikel.Dankuvooruwgedegencommentaar.

WolfgangBuhreenPeterBruins.Bedanktvoorhetkritischdoorlezenencorrigerenvanmijn

teksten.Jullieaanvullingenzijnergwaardevolgeblekenenhebbenmedevoordepublicatie

139

140 Dankwoord

vanmijnartikelengezorgd.

Marcel Durieux, als student ben ik via John Roord van de kindergeneeskunde bij jou een

onderzoeksstagegaandoenaandeUniversityofVirginiainCharlottesville.Ikhebdaareen

fantastische tijd gehad en het is ook nog een vruchtbare samenwerking gebleken. Mede

hierdoor heb ik de anesthesiologie herontdekt welke ik op genetische gronden eigenlijk

nooit als een serieuze optie tot specialisatie had gezien. Toen je professor in Maastricht

werd,hebikdanookserieusgetwijfeldof iknietooknaarhetzuidenmoestafreizen.Die

keus heb ik vanwege mijn sociale leven in Utrecht uiteindelijk niet gemaakt. Jij en je

gezin misten jullie leven in Virginia ook, waardoor jullie uiteindelijk ook weer daar zijn

teruggekeerd.Dankvoordesteundie ikvan jehebgekregenenhopelijkkunnenwe inde

toekomstnogeensietsgezamenlijksdoen.

Domenico Castigliego, we hebben samen heel wat afgepipetteerd. Het was echter nooit

saai om samen met jou zoveel standaardwerk te doen en ik heb erg genoten van onze

samenwerking.BovendienkunjeookfantastischItaliaanskoken.

StefanHavik,JoostMeijer.RegelmatigzijnDomenicoen iknaarAmsterdamafgereisdom

TAFI te meten in onze bloedmonsters. Na maanden werk is daar uiteindelijk helaas niets

uitgekomen.Desalnietteminwilikjulliebedankenvoorjulliehulphierbij.

Lab I: Chantal, Hanneke, Janine, Evelyn, Carine en Flip Jansen. Tijdens het vele wachten

tussendeexperimentendoor,washetaltijderggezelligenookbuitenhetwerkhebbenwe

elkaarregelmatiggezien.Hopelijkkunnenwedaargewoonmeedoorgaan.

Prof. Flip de Groot, Peter Lenting. De besprekingen waarin mijn onderzoeksresultaten

werden besproken, brachten vaak nuttige tips van jullie op. Bedankt voor de prettige

samenwerking.

Stefan,mijnkamergenoot. Ikvoeldemeafentoeeenbeetjeschuldigals ikzaghoehard

jijnaastmijsomsaanhetwerkwas.Jouwproefschriftzalongetwijfeldvangrotekwaliteit

zijn. Fellery, ik heb al meerdere malen gezegd wat voor bewondering ik heb voor jouw

doorzettingsvermogen. Met alle tegenslagen die je gekregen hebt, zou ik de handdoek al

langinderinggegooidhebben.Gelukkighebjijdatnietgedaan,waardoorjeuiteindelijk

tochovereenaantalmaandenindezelfdepositiealsikzalstaan.Veelsuccesmetdelaatste

loodjes.Alleanderemede-onderzoekers,dieopdeonderzoeksganghebbengebivakkeerd:

141

Olaf,Wilton,Teus,Suzanne,Jilles,Jolanda,BasenLidwien.Bedanktvoordegezamenlijke

lunches,congresbezoekenendiscussie’soveraldannietwetenschappelijkeonderwerpen.

Envoordiegenendienogevendoormoeten:succesmetschrijven!

StafledenvanonzedivisiePerioperatieveZorgenSpoedeisendeHulp.Hetvaltnietmeeom

onderzoekenkliniekmetelkaartecombineren.Dekliniekkwamtochvakeropeentweede

plaats en ik had soms het gevoel dat ik klinisch tekort schoot. Gelukkig heb ik van jullie

nooithetgevoelgekregendatditeengrootprobleemisgeweest.Bedanktvoorjulliegeduld

enbegripennatuurlijkjulliebijdrageomeengoedeanesthesioloogvanmijtemaken.Daar

gaathetuiteindelijkallemaalom.

Mijn collega’s arts-assistenten. Ondanks dat de assistentengroep in de loop der jaren

danig in omvang is toegenomen, blijft ze toch de gezelligste van heel anesthesiologisch

Nederland.Ikbenblijdatikhierdeelvanmaguitmaken.Bedanktvoorjulliebelangstelling

engezelligheid.

Mijnparanimfen:RubenenKorné.WieonsstraksindeSenaatszaalzietstaan,zaldenken

datikmetjullievoorietsprobeertecompenserenwatbijmijbeperktis:mijnlengte.Wijzijn

echteralgedurendedegehelegeneeskundestudievriendenenikbenblijdatjulliemijop

dezedagbijwillenstaan.Korné,ikvondheteeneerdatikjouwparanimfmochtzijn,enben

ergverheugddatjehetnuomgekeerdwiltdoen.Hopelijkbeniknetzoscherpzoalsjijdat

was.Ruben,alsjaarclubgenootenstudievriendvanheteerstejaarbenikblijdatjeookdit

belangrijkemomentmetmijwiltdelen.

Ookeeniederdieopenigerleiwijzeeenbijdrageheeftgeleverdaanditproefschrift,maar

ikhierbovenvergetenbenmetnametenoemenbenikzeerdankbaar.

Pa,jehadaltijdgezegddatikgeendoktermoestwordenenzekergeenanesthesioloog.Nu

ikondanksaldiegoedebedoelingentochhetzelfdecarrièrepadhebgekozen,weetikdatjij

daartochheeltrotsopbent.Daarnaasthebjemealtijdgestimuleerdonderzoektedoen,

omdatdatietsiswatjijookdooromstandighedenniethebtgedaan.Jouwkwaliteitenliggen

ophetklinischevlak,wantpatiëntenlopenwegmetjeenjewasdestijdssamenmetNigel

JackineenkleinstreekziekenhuisanesthesiologischNederlandaljarenvooruit.Ikhoopdat

iknetzoeengoedeanesthesioloogalsjijkanworden.

Ma,jijbentaltijddehoeksteenvanonsgezingeweest.Bedanktvoorjeonvoorwaardelijke

steunenbelangelozehulpwaardatooknodigwas.

Papi,mamidanseluruhkeluargabesarRuslydiJakarta,walaupunkaliansemuaberadajauh

disisiduniayanglain,sayabanggamenjadibagiandarikeluarga.Sayajugasenangdapat

datangkeJakartadantahubahwasayaakanselalumendapatkansaat-saatmenyenangkan

diJakartayangmembuatsayalupaakankesibukandiBelanda.Terimakasihatasdukungan

dancintadarikaliansemua.

Stefan, broertje. Het feit dat we maar één jaar en één dag schelen, bracht vroeger veel

competitiemetzichmee,maarzorgdeookvooreenuniekebroederband.Bedanktookvoor

jehulpmetallerleitechnischecomputerproblemen.

Toen ik aan dit promotietraject begon, had ik nog veel extra tijd omdat ik ‘happy single’

was. Daar is tijdens deze periode echter verandering in gekomen. Herny, ik heb enorme

bewonderingvoorje,datjijalleenvoormijzonderjouwgrotehechtefamilieineenvreemd

land met een vreemde taal helemaal opnieuw wilde beginnen. Ook de veel besproken

inburgeringscursusenadministratievechaosbijdeINDkondenjedaarnietvanweerhouden.

Ik ben erg blij dat je die stap genomen hebt, want jij laat me steeds weer zien waar het

allemaalomdraaitinhetleven.Ikzouhetdanookechtnietmeerzonderjoukunnen.

Patrick en Arlene, jullie zijn mijn grote inspiratiebronnen. Laten we samen nog heel veel

nieuwedingenopdezewereldontdekken.

Dankwoord142

CurrICuLuM VItAe

BernardLowasbornonFebruary21,1974inEindhoven,theNetherlands.Aftergraduating

highschoolattheRooms-KatholiekeScholenGemeenschap”Marianum”inGroenloin1992,

hestartedmedicalstudiesattheUniversityofUtrechtandgraduatedin2000.Duringhis

studiesin1997,hespentaresearchinternshipinthef ieldofAnesthesiologyattheUniver-

sityofVirginiainCharlottesville(supervisor:dr.M.E.Durieux).In2000Bernardbeganwor-

kingasaresidentattheDepartmentofPerioperativeCareandEmergencyMedicine.In2001

hestartedtheworkdescribedinthisthesis(promotor:Prof.dr.C.J.Kalkman)andsimultane-

ouslystartedhisspecialisttraininginAnesthesiology(chair:Prof.dr.J.T.A.Knape).

BernardLoismarriedtoHernySetiawatyRuslyandtheyhavetwochildren:Patrick(2004)

andArlene(2006).

CurriculumVitae 143

Publications144

PuBLICAtIonS

“Theeffectofcoffeeongastricemptyingandoro-caecaltransittime.”

BoekemaPJ,LoB,SamsomM,AkkermansLM,SmoutAJ

EurJClinInvest.2000Feb;30(2):129-34

“LocalanestheticeffectsonTXA2receptormediatedplateletaggregationusingquenchedflow

aggregometry.”

HoenemannCW,LoB,ErreraJS,Polanowska-GrabowskaR,GearAR,DurieuxME

AdvExpMedBiol.1999;469:269-76

“Organisatie en inhoud van het anesthesiologisch preoperatief onderzoek in Nederland: een

inventarisatie.”

WAvanKlei,CLGRutten,KGMMoons,BLo,JTAKnape,CJKalkman,DEGrobbee

NedTijdschrAnesth.2000;13(3)suppl:6

“Het effect van een Gezondheidsraad richtlijn over preoperatieve poliklinieken in Nederland:

eeninventariserendonderzoek.”

WAvanKlei,CLGRutten,KGMMoons,BLo,JTAKnape,CJKalkman,DEGrobbee

NedTijdschrGeneeskd.2001Jan6;145(1):25-9

“Localanestheticactionsonthromboxane-inducedplateletaggregation.”

LoB,HonemannCW,KohrsR,HollmannMW,Polanowska-GrabowskaRK,GearAR,DurieuxME

AnesthAnalg.2001Nov;93(5):1240-5

“Activationofhemostasisaftercoronaryarterybypassgraftingwithorwithoutcardiopulmonary

bypass.”

LoB,FijnheerR,CastigliegoD,BorstC,KalkmanCJ,NierichAP

AnesthAnalg.2004Sep;99(3):634-40

“C-reactiveproteinisariskindicatorforatrialf ibrillationaftermyocardialrevascularization.”

LoB,FijnheerR,NierichAP,BruinsP,KalkmanCJ

AnnThoracSurg.2005May;79(5):1530-5

“Activation of hemostasis is associated with early cognitive decline after off-pump coronary

arterybypasssurgery.”

LoB,FijnheerR,NierichAP,KalkmanCJ,vanDijkD

JThrombHaemost.2005Sep;3(9):2114-7

“Relatively increased von Willebrand Factor after off-pump coronary artery bypass graft

surgery.”

LoB,NierichAP,KalkmanCJ,FijnheerR

AcceptedbyThrombHaemost.2007

Activation of hemostasis after off-pump coronary artery...

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