AN INTRODUCTION TO THE 12 LEAD ECG.ppt

anintroductiontothe12leadecg sheelaghscottpracticedevelopmentcentrenhslanarkshire 12leadecginterpretation bytheendofthislecture youwillbeableto understandthe12leadecginrelationtothecoronarycirculationandmyocardiumperformanecgrecordingidentifytheecgchangesthatoccurinthepresenceofanacutecoronarysyndrome begintorecogniseanddiagnoseanacutemi whatisa12leadecg recordstheelectricalactivityoftheheart depolarisationandrepolarisationofthemyocardium viewsthesurfacesoftheleftventriclefrom12differentangles whydoa12leadecg monitorpatientsheartrateandrhythmevaluatetheeffectsofdiseaseorinjuryonheartfunctiondetectpresenceofischaemia damageevaluateresponsetomedications e gantidysrhythmicsobtainbaselinerecordingsbeforeduringandaftersurgicalprocedures recordinganecg explainproceduretopatient obtainconsentandcheckforallergiescheckcablesareconnectedensuresurfaceiscleananddryensureelectrodesareingoodcontactwithskinenterpatientdatawaituntilthetracingisfreefromartifactrequestthatpatientliesstill pushbuttontostarttracing procedure cont beforedisconectingtheleadsensuretherecordingis freefromartifactpaperspeedis25mm secnormalstandardisationof1mv 10mmleadplacementiscorrectecgislabelledcorrectly anatomyandphysiologyreview agoodbasicknowledgeoftheheartandcardiacfunctionisessentialinordertounderstandthe12leadecganatomicalpositionoftheheartcoronaryarterycirculationconductionsystem anatomicalpositionoftheheart liesinthemediastinumbehindthesternumbetweenthelungs justabovethediaphragmtheapex tipoftheleftventricle liesatthefifthintercostalspace mid clavicularline coronaryarterycirculation coronaryarterycirculation rightcoronaryarteryrightatriumrightventricleinferiorwallofleftventricleposteriorwallofleftventricle1 3interventricularseptum coronaryarterycirculationleftmainstemarterydividesintwo leftanteriordescendingarteryantero lateralsurfaceofleftventricle2 3interventricularseptumcircumflexarteryleftatriumlateralsurfaceofleftventricle coronaryarterycirculation thestandard12leadecg 6limbleads6chestleads precordialleads avr avl avf i ii iiiv1 v2 v3 v4 v5andv6rhythmstrip limbleadschestleads limbleads 3unipolarleadsavr rightarm avl leftarm avf leftfoot notethatrightfootisagroundlead limbleads 3bipolarleadsform einthovenstriangle leadi measureselectricalpotentialbetweenrightarm andleftarm leadii measureselectricalpotentialbetweenrightarm andleftleg leadiii measureselectricalpotentialbetweenleftarm andleftleg chestleads 6unipolarleadsalsoknownasprecordialleadsv1 v2 v3 v4 v5andv6 allpositive chestleads thinkofthepositiveelectrodeasan eye thepositionofthepositiveelectrodeonthebodydeterminestheareaoftheheart seen bythatlead surfacesoftheleftventricle inferior underneathanterior frontlateral leftsideposterior back inferiorsurface leadsii iiiandavflookupfrombelowtotheinferiorsurfaceoftheleftventriclemostlyperfusedbytherightcoronaryartery inferiorleads iiiiiavf anteriorsurface thefrontoftheheartviewingtheleftventricleandtheseptumleadsv2 v3andv4looktowardsthissurfacemostlyfedbytheleftanteriordescendingbranchoftheleftartery anteriorleads v2v3v4 lateralsurface theleftsidedwalloftheleftventricleleadsv5andv6 iandavllookatthissurfacemostlyfedbythecircumflexbranchoftheleftartery lateralleadsv5 v6 i avl posteriorsurface posteriorwallinfarctsarerareposteriordiagnosescanbemadebylookingattheanteriorleadsasamirrorimage normallythereareinferiorischaemicchangesbloodsupplypredominantlyfromtherightcoronaryartery inferiorii iii avf antero septalv1 v2 v3 v4 laterali avl v5 v6 posteriorv1 v2 v3 right left ecgwaveforms normalcardiacaxisisdownwardandtotheleftiethewaveofdepolarisationtravelsfromtherightatriatowardstheleftventriclewhenanelectricalimpulsetravelstowardsapositiveelectrode therewillbeapositivedeflectionontheecgiftheimpulsetravelsawayfromthepositiveelectrode anegativedeflectionwillbeseen ecgwaveforms lookatyour12leadecg swhatdoyounoticeaboutleadavr howdoesthiscomparewithleadv6 anintroductiontothe12leadecgpartii heartbeatoriginatesinthesanodeimpulsespreadstoallpartsoftheatriaviainternodalpathwaysatrialcontractionoccursimpulsereachestheavnodewhereitisdelayedby0 1secondimpulseisconductedrapidlydownthebundleofhisandpurkinjefibresventricularcontractionoccurs basicelectrocardiography thepwaverepresentsatrialdepolarisationtheprintervalisthetimefromonsetofatrialactivationtoonsetofventricularactivationtheqrscomplexrepresentsventriculardepolarisationthes tsegmentshouldbeiso electric representingtheventriclesbeforerepolarisationthet waverepresentsventricularrepolarisationtheqtintervalisthedurationofventricularactivationandrecovery ecgabnormalities associatedwithischaemia ischaemicchanges s tsegmentelevations tsegmentdepressionhyper acutet wavest waveinversionpathologicalq wavesleftbundlebranchblock stsegment thestsegmentrepresentsperiodbetweenventriculardepolarisationandrepolarisation theventriclesareunabletoreceiveanyfurtherstimulationthestsegmentnormallyliesontheisoelectricline stsegmentelevation thestsegmentliesabovetheisoelectricline representsmyocardialinjuryitisthehallmarkofmyocardialinfarctiontheinjuredmyocardiumisslowtorepolariseandremainsmorepositivelychargedthanthesurroundingareasothercausestoberuledoutincludepericarditisandventricularaneurysm st segmentelevation myocardialinfarction amedicalemergency stsegmentcurvesupwardsintheleadslookingatthethreatenedmyocardium presentswithinafewhoursoftheinfarct reciprocalstdepressionmaybepresent stsegmentdepression canbecharacterisedas downslopingupslopinghorizontal horizontalstsegmentdepression myocardialischaemia stableangina occursonexertion resolveswithrestand orgtnunstableangina candevelopduringrest nonstelevationmi usuallyquitedeep canbeassociatedwithdeeptwaveinversion reciprocalhorizontaldepressioncanoccurduringami horizontalstdepression stsegmentdepression downslopingstsegmentdepression canbecausedbydigoxin upwardslopingstsegmentdepression normalduringexercise twaves thetwaverepresentsventricularrepolarisationshouldbeinthesamedirectionasandsmallerthantheqrscomplexhyperacutetwavesoccurwiths tsegmentelevationinacutemitwaveinversionoccursduringischaemiaandshortlyafteranmi twaves othercausesoftwaveinversioninclude normalinsomeleadscardiomyopathypericarditisbundlebranchblock bbb sub arachnoidhaemorrhagepeakedtwavesindicatehyperkalaemia hyperacutetwaves inferiort waveinversion twaveinversioninanevolvingmi qrscomplex maybetoobroad morethan0 12seconds adelayinthedepolarisationoftheventriclesbecausetheconductionpathwayisabnormalaleftbundlebranchblockcanresultfrommiandmaybeasignofanacutemi wideqrs lbbb qrscomplex maybetootall thisiscausedbyanincreaseinmusclemassineitherventricle hypertrophy qwaves nonpathologicalqwavesqwavesoflessthan2mmarenormalpathologicalqwavesqwavesofmorethan2mmindicatefullthicknessmyocardialdamagefromaninfarctlatesignofmi evolved pathologicalqwaves anyquestions ecginterpretationinacutecoronarysyndromes theecginstelevationmi thehyper acutephase lessthan12hours stsegmentelevationisthehallmarkecgabnormalityofacutemyocardialinfarction quinn 1996 theecgchangesareevidencethattheischaemicmyocardiumcannotcompletelydepolarizeorrepolarizeasnormalusuallyoccurswithinafewhoursofinfarctionmayvaryinseverityfrom1mmto tombstone elevation thefullyevolvedphase 24 48hoursfromtheonsetofamyocardialinfarctionstsegmentelevationisless comingbacktobaseline twavesareinverting pathologicalqwavesaredeveloping 2mm thechronicstabilisedphase isoelectricstsegmentstwavesupright pathologicalqwaves maytakemonthsorweeks reciprocalchanges reciprocalchanges changesoccurringontheoppositesideofthemyocardiumthatisinfarcting reciprocalchanges theecginnonstelevationmi nonstelevationmi commonlystdepressionanddeeptwaveinversionhistoryofchestpaintypicalofmiotherautonomicnervoussymptomspresentbiochemistryresultsrequiredtodiagnosemiq wavesmayormaynotformontheecg changesinnstemi theecginunstableangina ischaemicchangeswillbedetectedontheecgduringpainwhichcanoccuratreststdepressionand ortwaveinversionpatientsshouldbemanagedonacoronarycareunitmaygoontodevelopstelevation unstableanginaecgduringpain anyquestions quickquizhowwellhaveyoulistened quickquiz mrjonesisdiagnosedashavinghadananteriormi onwhichleadswouldyouexpecttoseethemainchanges a ii iiiandavl b iandavl c v2 v4 quickquiz therightcoronaryarterymainlysupplies a theinferiorsurfaceoftheheart b theanteriorsurfaceoftheleftventricle c thelateralsurfaceoftheheart quickquiz mrjacksonhasecgchangessuggestiveofanmionleadsii iiiandavf whichsurfaceofhisheartisaffected a theanteriorsurface b thelateralsurface c theinferiorsurface quick