Jacobus ECG Tips

8/3/2019 Jacobus ECG Tips

1/19

ECGPrimer

ChristianJacobus,MD

RossUniversity

IntroductiontoClinicalMedicine

WhenIdictateECGsforapatientsmedicalrecord,Iusethefollowingformat:rate,rhythm,axis,

intervals,hypertrophy,ischemia.Forexample,Therateis60,therhythmissinus,axisisminus45

degrees,intervalsarenormal,thereisnoevidenceofhypertrophy,andnosignsofischemia.Sothat's

theorderinwhichI'mgoingtogooverthesetoday.

RateTherearetwoeasywaystofigureouttheheartratebylookingattheECG.

1) StandardECGsrecordfor10secondssoaneasywaytocalculatetherateistocountthenumberofQRScomplexesononepageandmultiplybysixtogetthenumberinonefullminute.

(#QRScomplexesononepage)*(6)=BPM

2) The300rule:countthenumberofbigboxesbetweentwoadjacentQRScomplexesanddivide300bythatnumber.Soonebigboxbetweencomplexeswillmeanaheartrateof300;twobig

boxeswouldbe150;threeis100;four

is75;fiveis60;sixis50.Thisismost

easilydonebyfindingonecomplexthat

fallsrightontoadarkerlineand

countingthenumberofbigboxesto

thenextQRScomplex.Ifthenext

complexfallsbetweenthelinesthen

youcanestimatebasedontheline

beforeandafter.Forexample,ifIfind

anR

wave

that

falls

right

on

adark

line,

andthenextRwavefallsbetweenfour

andfivebigboxeslater,thenIknowthe

rateisbetween75and60.Ifitscloser

tofourbigboxesthenImightestimate

70,closertofivebigboxesImightestimate65.

(300)/(#bigboxesbetween2adjacentQRScomplexes) =BPM

RhythmFirst,

some

basics.

The

Pwave

is

atrial

depolarization;

the

QRS

complex

is

ventricular

depolarization;theTwaveisventricularrepolarization(atrialrepolarizationoccursatthesametimeas

ventriculardepolarizationandsoislostintheQRScomplex).Whentheventriclesdepolarizenormally,

currentmovesthroughtheHisPurkinjesystem,specializedcellsthatconductelectricalchargequickly,

likeelectricalwiringfortheheart.Becausetheypropagatethatwaveofdepolarizationquickly,and

becausetimeequalshorizontaldistanceonECG,anormalQRScomplexisnarrow.

Incontrast,slowdepolarizationcausesawidenedQRScomplexbecausetimeisonthexaxisof

anECG,asstatedabove.Forinstance,whendepolarizationstartsintheventricularmyocardiumand


2/19

spreadsfrommyocytetomyocyteitisnotusingtheHisPurkinjesystemandsodischargepropagates

moreslowly.TheothercauseforawidenedQRSisablockintheHisPurkinjesystem,delaying

depolarizationandwideningthecomplex.

SinusrhythmisaregularrhythmwithaPwaveoccurringbeforeeveryQRScomplex.TheseareheartbeatsthatoriginateintheSAnode.

JunctionalrhythmisanimpulsethatbeginsintheAVnoderatherthantheSAnode.IftheSA

nodeisdiseasedorischemicitwillnotfunctionproperly,causingtheAVnodetohavetotakeover

pacemakingduties.TheAVnodehasanintrinsicratethatisslowerthantheSAnode:4060bpm(vs.

theSAnodewhichis60100).ThesecomplexesdontusuallyhaveaPwavebecausethechargestarts

intheAVnodeandgoesdowntotheventricles.Atthesametime,thecurrentdoesgobackuptothe

atria,butbecausethisoccursatthesametimeastheventriculardepolarization,thePwaveislostinthe

QRScomplex.Ifthecurrentgetstotheatriaslightlybeforetheventricles,youmayseeinverted

(becausethewaveofdepolarizationisgoingup,ratherthandown)Pwavesimmediatelybeforethe

QRS.SoontheECGyoullseeslow,regular,narrowQRScomplexeswithnoPwavesbeforethemorinvertedPwaves.

Anidioventricularrhythmoriginatesinthemyocardiumoftheventriclesthemselves.Incases

wheretheSAnodeandtheAVnodearebothdiseasedorischemicandnotgeneratingimpulses,the

ventricularmyocyteshavetotakeover.Theirintrinsicrateis2040bpm.Becausethechargesarenot

travelingthroughtheHisPurkinjesystemthesecomplexeswillusuallybewideandbizarrelookingandtheratewillbeslow.

Atrialfibrillation:inthisrhythmtheatriahaveuncoordinatedelectricalactivity,kindoflike

they'rehavingaseizure.TheAVnodeisgettingbombardedwithelectricalsignalsbecauseofallthis

electricalactivity.WhentheAVnoderesetsfromthepreviousfiring,itisreadytofireagainandwilllet

thenextchargeitreceivesthrough,whichisthenconducteddowntotheventricles.Becausethecharge

goesthroughtheAVnode,therestofthechargeisconductednormally,propagatingdowntheHis

Purkinjesystem.AsaresulttheQRScomplexesarenarrow(i.e.normal).EverytimetheAVnoderesets

itwaitsforthenextcurrent,whichstartsthecycleoveragain.Becausetheelectricalactivityintheatria


3/19

isuncoordinatedandunpredictablethenextchargecouldoccurinonemillisecondor1000.Thus,the

frequencywithwhichachargeissentdowntotheventriclestoactuallygenerateaheartbeatis

irregular.Sowhatyouseeisawavybaseline,causedbythefibrillatingatria,andirregular,narrowQRScomplexes.

SVT:thisisaprettynondescriptivename.SVTstandsforsupraventriculartachycardia,whichjust

meansanytachycardia(rategreaterthan100)causedbydischargesabovetheventricles.Soanything

fastand

coming

from

above

the

ventricles

would

qualify:

sinus

tachycardia,rapidafib,etc.Whatweusuallymeanwhenwe

saySVTisactuallyAVNRT:AVnodalreentrytachycardia.The

ideaisthatyouhaveapathwayinoraroundtheAVnode,

which,inadditiontoconductingthechargedownthelengthof

theventricles,alsoloopsbackuptowardstheAVnode.So

whentheAVnodefiresmostofthechargecontinuesdownto

theventriclesandmakethemfirenormally,butsomecharge

willridethatloopingpathwaybackaround.IftheAVnodeis

readytofireagainthatchargewillsetitoffearlierthanusual

andyougetafastercycle:theAVnodefires,thechargeloops

aroundandmakesitfireagain.Thiscanresultinheartratesof

over200.

So

think

about

what

we'd

see

on

ECG.

Pwaves?

ProbablynotsincethechargeiscomingfromtheAVnodeso

thisislikeajunctionalrhythm.SincethechargestartsintheAV

nodeitdepolarizestheventriclesthenormalwaybutitdepolarizestheatriagoingup.Soyoumightsee

aninvertedPwaverightbeforetheQRS(closerthanusual),youmightseenoPwaves(becauseitislost

intheQRScomplex),oryoumightseealittlePwaveaftertheQRS.TheQRSwillbenarrow(normal)

sincedepolarizationisoccurringdowntheHisPurkinjesystem.ClassicallythiswillbeaveryfastratewithnarrowQRScomplexesandnoPwaves.IntheexamplebelowthesmallwavesbetweentheQRScomplexesareTwaves,notPwaves.


4/19

Ventriculartachycardia:thisoccurswhenanirritatedareaofmyocardiumsomewhereinthe

ventriclesstartstofireonitsown,withoutwaitingforachargefromtheHisPurkinjesystem.Irritation

canbecausedbyischemia,electrolyteimbalance,trauma,orotherreasons.Themyocardiumstarts

firingandjustkeepsgoing.Becausethecurrentstartsintheventricularmyocardium,thechargeisgoing

tospreadmyocytetomyocyteratherthandowntheHisPurkinjesystem.SoonECGyou'llseewideQRScomplexesoccurringataveryfastrate.IthinkthatitoftenlookslikeabunchofMcDonaldssignsinarow.

Ventricularfibrillation:thisisuncoordinatedelectricalactivityintheventricles,justlikea

seizure.Thereisnocoordinatedelectricalactivityatalland,hence,nocontraction.OnECGthisjust

lookslikeawavyline.

Asystole:thisisnothing,noelectricalactivityatall.OnECGthislookslikeasimplestraightline.

AxisMeanelectricalaxis(MEA)isprobablythemostdifficultpartofECGinterpretationtoteach.SoIll

giveyoumyquickanddirtymethodaswellasmymoreformalway.


5/19

Quick

handisg

aVF.Poin

positivet

pointing

Ifp

If

If

anddirty:lo

ingtorepre

tyourthumb

anyourleft

own.

bothofyour

ositive,then

yourleftthu

yourrightth

okatleadIa

entleadI.a

sinthedirec

thumbwillb

thumbsare

you'reliketh

mbisupand

umbisupan

ndaVFonth

Fisontheri

tionoftheQ

epointingup

up,meaning

eFonz(Aaaa

yourrightth

dyourlefto

eECG.LeadI

ghtsideoft

RScomplexi

,ifleadaVF

thattheQRS

y!),twothu

umbisdow

eisdownth

isontheleft

epagesoyo

neachlead,

isnegativeth

complexesi

bsupandt

thenyouha

enyouhave

sideofthep

urrighthand

orexamplei

enyourrigh

leadIanda

eaxisisnor

vealeftaxis

arightaxis

agesoyourl

willreprese

fleadIismo

thumbwill

VFaremainl

al.

deviation.

eviation.

eft

nt

stly

e


6/19

Ifu

The

1

2

S

bothofyour

nusual.

oreindept

) Weonlyu) AnECGledepolariza

depolariza

depolariza

thisismyp

thumbsare

version.We

sethelimbl

dislikeane

tioncoming

tiongoinga

tiongoingp

referredmet

downtheny

needtolay

adstocalcul

yeball,itsee

towardsmeI

ayfromme

rpendicular

hod.

uhaveane

ownacoupl

atethemea

electricity.I

'lldeflectth

I'lldeflectth

omeI'lldefl

tremeright

eofassump

electricala

fIamanele

ECGtracing

eECGtracin

ecteithereq

axisdeviatio

ionsfirst.

is(I,II,III,aV

trodeandI

up;ifIseea

down;ifIse

uallyupand

nwhichisve

R,aVL,aVF).

eeawaveof

waveof

eawaveof

downornot

ry

atall.


7/19

1) Findthelimbleadthatisthemostisoelectric(i.e.netdepolarizationzero)2) Weknowfromnumbertwoabovethatthismeansthatthewaveofdepolarizationis

travelingperpendiculartothelead,right?

3) Sofromlookingatthediagrambelow(amodificationofEinthovenstriangle)wecanseethatifweknowtheaxisisperpendiculartoaleadthenwehavetwochoices,itcanbe

perpendicularcomingfromtherightoftheleadandgoingtotheleftofthelead,orthe

otherwayaround.Forexample,lookingatthediagrambelow,iftheaxisisperpendicularto

leadIIthenithastobeeither 30or+150.Sowhichisit?Well,let'slookatthe

perpendicularlead.IftheQRScomplexesaremorepositiveinthatleadthentheaxisis

goingtowardthatlead;iftheyremorenegativethentheaxisisgoingawayfromthatlead.

4) Usethisaxisdrawingtohelp:

Examples:

SothemostisoelectricleadhereisaVL.


8/19

Sinceweknow,then,thatthemeanelectricalaxismustbegoingperpendiculartoaVL,then(bylookingatourleadsinthediagramabove)itmustbeeither+60or 120.

Todeterminewhichofthoseitis,welookattheleadthatisperpendiculartoaVL,whichisleadII.IftheQRScomplexispositiveinIIthenitmeansthatcurrentiscomingtowardsitandtheaxis

mustbe+60.IftheQRScomplexisnegative,thenchargemustbemovingawayfromitandthe

axiswouldbe 120.

TheQRSinleadIIispositive,sotheaxisisabout60,whichisnormal,whichconfirmsourthumbsupmethod.

Anotherexample:

ThemostisoelectricleadhereisaVR.aVFisprettyclose,butitseemstomelikeaVRismoreequallyupanddown.

SotheaxismustbeperpendiculartoaVRwhichwouldbe,whenlookingattheaxisdiagramabove,+120or 60.SowegototheleadperpendiculartoaVRtodecidewhichwaytheaxisis

going,towards+120or 60.

TheleadperpendiculartoaVRisleadIII.LeadIIIislocatedat+120.Soifthecomplexispositivethenchargeismovingtowardstheleadandtheaxisis120;ifthecomplexisnegative,then

chargeismovingawayfromtheleadandtheaxisis 60.

ThecomplexinleadIIIisnegative,sothatmeansthatthemeanelectricalaxisis 60.Thisisaleftaxisdeviation,andjiveswithourthumbsupmethod.

Onemoreexample:


9/19

ThemostisoelectricleadhereisleadII.Soweknowthatthechargeismovingperpendiculartoitwhichwouldbe+150or 30.

TofindoutwhichoneitiswelookattheleadthatisperpendiculartoleadIIwhichisaVL.WeknowthataVLislocatedat 30soifthecomplexinaVLispositivethenchargeismoving

towardsaVLandtheaxisis 30;ifthecomplexisnegativethenchargeismovingawayfromit

andtheaxisis+150.

TheQRScomplexinaVLisnegative,meaningthattheaxisis+150.Thisisarightaxisdeviationandalsocorrespondstoourthumbsupmethod.

Soafterdoingthatwecanseewhythethumbsupmethodworks.IfleadIandaVLarepositive

thentheaxismustbesomewhereinthequadrantbetweenzeroand90sincethat'stheonlyareathat

willmake

both

leads

positive.

Onastandard12leadECG,theperpendicularleadsarearrangedlikeso:


10/19

Ii

Intervals

T

aretheP

QTinterv

though:a

occurring

stretchof

onewave

between

intervali

Qwavet

A

thatitto

istheent

thebaseli

thesame

P

fromthe

littlebox

ThePRin

longPRin

theendo

Rememb

depolariz

sperpendic

hemainECG

interval,th

al.Aquickw

segmentis

betweentw

ECGtracing

.SotheSTs

theSwavea

the

area

fro

theendoft

lsonotefro

kmeyearst

ireportiono

ne,ratherth

appliesfort

Rinterval:th

beginningof

sor

0.12

to

tervalprimar

tervalusuall

RSinterval:t

fthelastwa

rwhatwes

estheheart

lartoaVF;II

intervalswe

QRSinterva

rdondefini

stretchofE

waves,ani

thatincludes

gmentisthe

dthePwav

mthe

beginn

heTwave.

thisdiagra

ofigureout:

theQRSco

anjustthefi

eQandSw

isameasure

thePwavet

.20seconds.

ilyrepresent

indicatesso

hisisameas

e.Itreprese

idearlier:n

uickly.Soth

isperpendic

measure

l,andthe

ions,

Gtracing

tervalisa

atleast

area

e;theQT

ingof

the

something

theRwave

plexabove

stupslope;

ves.

ofthetime

thebeginni

We

will

loo

thedelayt

mekindofd

urementfro

ntsthetimei

rmalconduc

eQRSshould

lartoaVL;II

ngoftheQR

at

abnorma

attheelectr

iseaseatthe

thebeginni

ttakesforth

tiontravelst

benarrow,

Iisperpendi

complex.A

litiesof

the

P

icalsignalun

AVnode.

ngofthefirs

eventricles

hroughthe

rlessthant

ulartoaVR.

normalPRin

Rinterval

in

dergoesatth

twaveofth

ocompletel

isPurkinjes

hreelittlebo

tervalis3to

fewminute

eAVnode.S

QRScomple

depolarize.

stemandth

xes,0.12sec

5

s.oa

xto

us

nds.


11/19

AwiderQRScomplexusuallymeansslowconductionintheventricleseither1)becausetheimpulse

startedintheventriclesandisspreadingmyocytetomyocyteratherthanusingtheHisPurkinjesystem

or2)becauseofadefectorablockinoneofthebundlebranchesoftheHisPurkinjesystem.Moreon

thoseinafewminutes.

QTinterval:theQTintervalismeasuredfromthebeginningoftheQRScomplextotheendof

theTwave.Itisameasureofthetimefromthebeginningofdepolarizationtotheendofrepolarization

butsincedepolarizationissoshortitismainlyameasureofthetimetorepolarizetheventricles.The

QTintervalwillchange,though,dependingontheheartrate.Aheartbeatingfastneedsashort

repolarizationtimewhileonebeatingslowlycantakelonger.SoweapplyacorrectiontotheQTinterval

toaccountfortheheartrate.ItiscalledtheQTc(QTcorrected).TheformulaisQTdividedbythesquare

rootoftheRRinterval:

AnormalQTcislessthan0.44seconds(11littleboxes).Ausefulquickanddirtymethodfor

checkingtheQTcistodrawalineverticallyupfromtheendoftheTwave.Nowdrawalinebetweenthe

topoftheRwavebeforeandthetopoftheRwaveafter.IftheendoftheTwaveislessthanhalfthe

wayto

the

next

R

then

it's

likely

in

the

normal

range.

Long

QT

syndrome

can

be

congenital

or

acquired

andisdangerousbecauseitcanleadtoTorsadesdePointe.

Example:

Inthisexample,theendoftheTwavefallslessthanhalfwaybetweenthe2Rwaves,andsois

mostlikelynormal.

Anotherexample:

Inthisexample,theendoftheTwavefallsmorethanhalfofthedistancetothenextRwave

andsoisprolonged.


12/19

PRintervalabnormalities/AVBlocks:aswesaidbefore,alongPRintervalusuallymeanssome

sortofpathologyattheAVnodesincethePRintervalmainlymeasurestimebetweenatrial

depolarizationandventriculardepolarization,thetimewhenthechargeisbeingdelayedbytheAV

node.Solet'stalkaboutafewblocks,therearefourthatyouneedtoknow.

Firstdegree:thisissimplyalongerthanusualdelayattheAVnode,manifestedbyafixedPRintervalthatislongerthan0.20seconds.Itisbenignanddoesn'tneedanyimmediatetreatment.

SeconddegreetypeI:thisisaPRintervalthatgetslongerwitheachbeatuntiliteventuallyblocksthedepolarizationcompletelyleadingtoadroppedQRScomplex.It'salsoknownasMobitzIorWenckebach.(Ifyouhaven'talreadyseenitIhighlyrecommendwatchingDiagnosis

WenckebachonYouTube.)Thisisalsoabenignrhythmandneedsnourgentintervention.

SeconddegreetypeII:thisisaPRintervalthatisnormalandunchangingwiththeexceptionthatoccasionallythePwaveswilloccurwithoutaQRS i.e.theAVnodeblockstransmissionofanimpulsefromtheatriatotheventriclescompletely.Thisisconsideredamalignantblock

duetoitstendencytodeteriorateintoathirddegreeheartblock.

8littleboxes=0.32sec

Normal Long Longer DroppedQRS

Dropped

QRS Dropped

QRS


13/19

Tb

t

t

r

is

t

r

Asho

ofanacc

intervalis

withoutg

QRSi

timeitta

impulset

Purkinjes

hirddegree(

etweenthea

avesbutno

eventricles,

eventricles

gularPwav

noconnecti

reateningbl

arkedbelow

gardforan

rtPRinterva

ssorypathw

shorterbec

oingthrough

ntervalabno

esforthev

hatstartsin

ystem,or2)

completehe

triaandthe

eofthoseat

itappearsa

needtotake

esandregul

nbetweent

ockandman

,youcansee

rmalorder.

l,inconjuncti

aybetweent

usethedep

thedelayat

malities/Bun

ntriclestofu

heventricles

animpulset

rtblock):thi

entricles.Th

rialdepolari

iftheSAan

overpacem

rQRScomp

hematall.T

datesurgent

thattheyse

onwithade

heatriaand

larizationca

theAVnode

dleBranchB

llydepolariz

andhastos

atstartsnor

siswhereth

eatriaconti

ationsareg

AVnodesh

kingdutiest

exesbutocc

eQRScomp

intervention

emtomarch

ltawave(cir

theventricle

ngostraight

.

locks:aswe

.Thiscanbe

preadmyocy

mallybutth

ereisacom

uetobeata

ttingconduc

avestopped

hemselves.S

urringatco

lexescanbe

,usuallyapa

throughthe

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s,suchasin

fromtheatr

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delayedfor

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leteelectric

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pletelydiff

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QRScomple

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heQRSinter

oneoftwor

e,whichissl

uctionblock

ldisconnecti

cingregular

theventricle

pletelyandt

eonthestri

rentrates.T

de.Thisisal

Pwavesar

eswithouta

estheprese

onWhite.Th

theventricle

alrepresent

asons:1)an

werthanth

intheHis

on

P

s.To

us

pis

here

ife

ny

ce

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s

sthe

His


14/19

Purkinjes

leftandri

Asyo

blocking

depolariz

158ofDa

blockwill

complex

yourima

aQRSco

V6which

LBBB:

RBBB

Hypertro

V

hypertro

counting

LVH:

bediagno

1) Tb

2) T

ysteminthe

ghtbundleb

umayreme

feitherone

ation.Therei

vis,QuickanhaveaQRS

oftenwithb

ination)in

plexgreate

isonthelef

:

hy

entricularhy

hyaswell.D

boxes.

herearethr

sedasLVH.

heSwavein

igboxes).

heRwavein

ventricles.T

ranchblocks.

ber,thebu

ofthesebra

sagooddes

dAccurate1urationgre

unnyears:a

1whichiso

rthan0.12s

sideofthec

pertrophyis

iagnosingLV

emainform

V1(blue)plu

aVL(red)isg

etwomain

dleofHissp

cheswillcau

riptionofwLeadECGInterthanthr

QRScomple

therightsi

econdsand

hest.

oingtobeo

HandRVHis

ulastoknow

stheRwave

reaterthan

conductionb

litsintotwo

seawideQ

ythecharac

terpretation.

elittleboxe

thathastw

eoftheche

positiveQR

urmainfocu

reallyjusta

forLVH;ifa

inV5orV6(

requalto11

lockswewill

undlebranc

Scomplexd

teristicECG

Forourpur

s(0.12seco

opositivede

st.Aleftbun

complex(a

sbutwewill

atterofre

ECGmeets

green)isgre

mm

discussinth

hes,theleft

uetoadelay

indingsoccu

osesaright

ds)andapo

flections,an

dlebranchbl

lsooftenwit

touchbriefly

emberingfo

anyoneoft

terthanore

eventriclesa

ndright.A

incomplete

ronpages1

undlebranc

sitiveQRS

RandanR,

ockwillalso

bunnyears

onatrial

rmulasand

esecriteriai

qualto35m

re

2to

h

use

have

)in

tcan

m(7okolow Criteria:


15/19

3) TheRwaveinV5orV6(purple)isgreaterthanorequalto27mm.

Ifyounotice,allofthesecriteriahaveincommonthatyouarelookingforabigpositivedeflection

ontheleft(aVLandV5andV6)andabignegativedeflectionintherightleads(V1).

RVH:sameidea,youonlyneedtomeetoneofthecriteriabelow,buttheformulasare:

21mm

25mm

22mm

37mm


16/19

1. R2. t

Again,he

deflectio

Lefta

1) ad

s

b

2) Aaa

r

n

Right

leadII.So

waveinV1(

eRwavein

reweareloo

inthelefts

trialhypertr

notchedor

istentionor

condpeaki

ottomleftof

hichishand

largenegati

triumdepola

triumdepola

sultingina

egativedefl

atrialhypert

inrightatria

purple)isgre

1plustheS

kingforabi

idedleads(V

phy:therea

shapedPw

ypertrophy

thedepolari

thebodywh

becausethe

eportionof

rizesthe

cha

rizes,becaus

egativedefl

ctioninthe

rophy:theri

lhypertroph

aterthanth

waveinV6i

positivedefl

).

retwomain

aveinleadII

ndsothefir

zationofthe

ichiswherel

leadIIPwa

thePwavei

gemoves

to

etheleftatri

ction.Soift

waveofle

htatriumde

therewillb

SwaveinV

greatertha

ectioninthe

riteriatolo

.Theleftatri

stpeakisthe

leftatrium.

eadIIislook

veslookslik

V1.V1ison

ardsthe

le

umismorep

eleftatriu

dV1.

polarizesdo

etallPwave

orequalto

rightsidedl

kforinleft

aldepolariza

depolarizati

heyarebot

ingfrom.Thi

anM.

theanterior

dgiving

apo

osterior,the

ishypertro

nandtoth

sinleadII,

11mm.

eads(V1)an

trialhypertr

tionisdelaye

onoftherigh

positivewh

sfindingisca

chestsowh

sitivedeflect

chargemov

hiedyou'llg

left,almost

iggerthan2.

abignegati

phy:

ddueto

tatrium,the

enseenfrom

lledPmitralntheright

ion.When

t

sposteriorly

talarge

directlytow

4mm.

ve

the

eleft

rds


17/19

IschemiaT

1) Tr

r

c

p

2)t

herearethre

waveinversi

hythisoccur

polarization

polarization

angescanr

ersistforwe

waves:Qw

eyare:

a. widerb. greate

fromt

emainECGs

ons:Ihaveb

s,butitdoes

ofcardiacm

reversesand

presentcurr

kstomonth

ves(theiniti

than0.04se

rthanonet

hesamecom

ignstolook

eenunablet

.Ischemiah

ocytes.Inm

theTwave,

entorrecen

sbeforenor

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Jacobus ECG Tips

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