Fysiologie Van de Coronaircirculatie_PWouters

8/2/2019 Fysiologie Van de Coronaircirculatie_PWouters

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(Patho-)fysiologie van dekransslagader doorbloeding

Patrick Wouters


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Postoperatief myocardinfarct = Belangrijkste

doodsoorzaak na chirurgie 1.3 % in ptn met risico (cardiale complicaties ~ 4 %)

0.3 % in globale populatie (cardiale complicaties ~ 1.5 %)

Hoge Incidentie Ischemische Hartziekte

Ouder wordende populatie

Vaak niet gediagnosticeerd

Intraoperatieve Myocardischemie =

Verhoogd Risico postop myocardinfarct

FACTS


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physiological framework

1. Keeping balance between metabolic supply and demand

= physical laws of hydraulics & oxygen transport

2. Preventing intravascular thrombosis

= Integrity of the endothelium / endovascular wall= Control over coagulation/thrombosis & inflammatory state


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PERFUSION

PRESSURE

DIASTOLIC PHASE

(1/HR)


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Zuurstofaanbod in de coronaircirculatie

zuurstof inhoud(CaO2) x aanbod van bloed (CBF)

A B

A : (1.4 x Hemoglobine x SpO2) + (PaO2 x 0.003)

vb 1.4 x15 g/dl x 100% + 150 mmHg x 0.003

20 ml / 100 ml 0.45 ml

vb 1.4 x 10 x 100 + 600 x 0.003

14 ml / 100 ml 1.8 ml

FFA - lactate - glucose


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Zuurstofaanbod in de coronaircirculatie

zuurstof inhoud(CaO2) x aanbod van bloed (CBF)

A B

B : CBF = CPP / CVR ~ (I = U/R)

250 ml per minuut in rust

kan normaal tot 5 x stijgen bij inspanning

zuurstof extractie is ~ maximaal (in de LV) !


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CPP : drukgradient tussen aorta en ventrikel

Bepaald door :

Diastole ABPLV EDP

en

Diastole duur


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Heart Rate (bmp)

%D

ia

stole

30

30

50 70 90 110 130 150

40

50

60

70

80

EDV


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PERFUSION

PRESSURE

DIASTOLIC PHASE

(1/HR)

PERFUSION

PRESSURE

DIASTOLIC PHASE

(1/HR)


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AoPdiast LVEDP

CVR : wet van Ohm

P R F autoregulation


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pathofysiologie


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Kritische stenose


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PERFUSION

PRESSURE

DIASTOLIC PHASE

(1/HR)

O2 Demand


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Contractility & Relaxation


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Contractility


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Loading conditions


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Nitraten


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POISE Results + Prophylactic

Periop-Blockade

PeriOperative ISchemic Evaluation Trial

190 hospitals, 8351 patients

MI in metoprolol gp vs placebo (4.2 vs 5.7%)BUT :

stroke in metoprolol gp (1.0 vs 0.5%)

mortality in metoprolol gp (3.1 vs 2.3%)

-blockers risk, especially in context of anemia +

hypotension

POISE Study Group; Devereaux PJ, Yang H, et al; Lancet 2008;371:1839-47.


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PERFUSION

PRESSURE SUPPLY DEMAND

General Anesthetics =- sympathetic withdrawal

- mild contractile depression- afterload reduction

SUPPLYDEMAND


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table 4. Hemodynamic Stability from Induction of Anesthesia toOnset of Cardiopulmonary Bypass in 1,012 Patients who

Received Four Different Primary Anesthetics

Anesthesiology 70 ;179-188, 1989

* Totals of columns exceed 100% because some patients had more than one abnormality at the same or different times.


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Anesthesiology 70 ;179-188, 1989

Majority of ischemic events unrelated

to hemodynamic changes !


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Falk et al, 1995

0

20

40

60

80

100

68%

18%

14%>70%

5070%


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Shear Stress

Inflammation

Plaque ruptureConsolidation

Natural Healing

Process


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Pathophysiology of Acute Coronary Syndromes

Balancing the Stability Equation

Repair ThrombosisInflammation

Stable Plaque Unstable Plaque


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perioperative myocardial infarction

acute coronary thrombosis myocardial ischemia

inflammation hypercoagulability stress tissue hypoxemia

plaquefissuring

increasedcatecholamine+ cortisol levels

oxygendelivery

plaquefissuring

coronary arteryshear stress increase in

blood pressureand heart rate

oxygendemand

surgery anesthesia

surgery anesthesia

hypothermia anemiapain

hypotension hypoxemia hypervolemia tachycardia anemia

Courtesy of S. De Hert


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N Engl J Med, Vol. 347, No. 17

ASPIRIN AND MORTALITY FROM CORONARY BYPASS

SURGERY

MANGANO & MULTICENTER STUDY OF PERIOPERATIVE ISCHEMIA RESEARCHGROUP


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Aspirin withdrawal

- Hyperaggregability

- Reduced fibrinolysis


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de Souza DG, Baum VC, Ballert NM: Late thrombosis (> 1 year) of

a drug-eluting stent presenting in the perioperative period.

ANESTHESIOLOGY 2007; 106:10579

A i i fl


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Anti-inflammatory treatment

Statins

JAMA. 2004 May 5;291(17):2092-9

J Vasc Surg 2004;39:967 : RCT statins > 2 weeks preop = 3.1 fold reduction CVE

n = 780.000


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Reduce lipid accumulation

Reduce inflammatory cell infiltration

into plaques

Accumulation of modified lipid

Endothelial cell activation

Inflammatory cell migration

Inflammatory cell activation

VSMC recruitment

VSMC proliferation and matrix synthesis

Fibrous cap formation

Plaque rupture

Platelet aggregation

Thrombosis

Inhibit platelet aggregation

Pleiotropic effects of Statins

Reduce blood thrombogenicity

Normalize endothelial cell function

Effects on VSMC

proliferation and matrix

synthesis

differ between statins

Perioperative ischemia


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A change of paradigm

from hydraulic model tothe vulnerable plaquemodel

Current Diagnostic methods fail to fully assess risk

Managing Oxygen supplydemand is insufficient to preventMI

Treatment strategies should focus on control of

Inflammation Thrombosis

Reduction of Shear Stress

e ope at e sc e a


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To remember

Hemodynamic management :

Preserve diastolic perfusion pressure

no tachycardia

Avoid hypoxia, extreme anemia (?)

Non-hemodynamic related ischemia :

beta blockade and stress prevention (pain-shivering)

Postoperative Anti-thrombosis


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The ischemic syndromes


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The wavefront phenomenon of

Acute Myocardial Infarction


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Myocardial Stunning : temporary reversible dysfunction


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Myocardial Stunning


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Myocardial Hibernation : persistent (but reversible ?)

dysfunction


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Ischemia

Imbalanced

Progressive

Inotropes harmful

Stunning

Balanced

Progressive

Inotropes Useful

Hibernation

BalancedSlowly Progressive

Inotropes harmful

at high dose


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Myocardial Protection


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5

10

15

20

25

30

35

Infarctsize

(%

ofareaatrisc)

O1

.5

.10

.15

.20

.25

.30

.35

C

ollateralFlow

(ml/min.gm)

O2 O3 O4

R1 R2 R3 R4

40 ' OCCLUSION

40 ' OCCLUSION

Preconditioned

Control

day 4

Murry et al. Circulation 1986


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Anesthesiology 1999; 91:1437-46

M h i A th ti


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Mechanisms Anesthetic

PreconditioningTriggersMediatorsEffectors

TM

E

Fysiologie Van de Coronaircirculatie_PWouters

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