Basic Electrocardiography: Normal and Abnormal ECG Patterns PDF
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P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 Basic Electrocardiography NORMAL AND ABNORMAL ECG PATTERNS i P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 Basic Electrocardiography NORMAL AND ABNORMAL ECG PATTERNS A. Bayés de Luna,MD, FESC, FACC ProfessorofMedicine,UniversidadAutonomaBarcelona DirectorofInstitutCataladeCardiologia HospitalSantaCreuISantPau St.AntoniM.Claret167 DirectorCardiacDepartment–H.Quiron.Barcelona ES-08025 Barcelona Spain iii P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 (cid:2) C 2007A.BayésdeLuna PublishedbyBlackwellPublishing BlackwellFuturaisanimprintofBlackwellPublishing BlackwellPublishing,Inc.,350MainStreet,Malden,Massachusetts02148-5020,USA BlackwellPublishingLtd,9600GarsingtonRoad,OxfordOX42DQ,UK BlackwellScienceAsiaPtyLtd,550SwanstonStreet,Carlton,Victoria3053,Australia Allrightsreserved.Nopartofthispublicationmaybereproducedinanyformorbyany electronicormechanicalmeans,includinginformationstorageandretrievalsystems,without permissioninwritingfromthepublisher,exceptbyareviewerwhomayquotebriefpassages inareview. Firstpublished2007 1 2007 ISBN:978-1-4051-7570-8 LibraryofCongressCataloging-in-PublicationData BayesdeLuna,Antonio. Basicelectrocardiography:normalandabnormalECGpatterns/AntoniBayesdeLuna. p.;cm. Includesbibliographicalreferencesandindex. ISBN978-1-4051-7570-8 1.Electrocardiography. 2.Heart–Diseases–Diagnosis. I.Title. [DNLM:1.Electrocardiography. 2.Electrocardiography–methods. WG140B357b2007] RC683.5.E5B3242007 616.1(cid:3)207547–dc22 2007006646 AcataloguerecordforthistitleisavailablefromtheBritishLibrary CommissioningEditor:GinaAlmond DevelopmentEditor:FionaPattison EditorialAssistant:VictoriaPitman Setin9.5/12ptPalatinobyAptaraInc.,NewDelhi,India PrintedandboundinSingaporebyFabulousPrintersPteLtd. ForfurtherinformationonBlackwellPublishing,visitourwebsite: www.blackwellcardiology.com Thepublisher’spolicyistousepermanentpaperfrommillsthatoperateasustainableforestry policy,andwhichhasbeenmanufacturedfrompulpprocessedusingacid-freeandelementary chlorine-freepractices.Furthermore,thepublisherensuresthatthetextpaperandcoverboard usedhavemetacceptableenvironmentalaccreditationstandards. BlackwellPublishingmakesnorepresentation,expressorimplied,thatthedrugdosagesinthis bookarecorrect.Readersmustthereforealwayscheckthatanyproductmentionedinthis publicationisusedinaccordancewiththeprescribinginformationpreparedbythe manufacturers.Theauthorandthepublishersdonotacceptresponsibilityorlegalliabilityfor anyerrorsinthetextorforthemisuseormisapplicationofmaterialinthisbook. iv P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 Contents Foreword,vii 1 Introduction,1 2 Usefulnessandlimitationsofelectrocardiography,4 3 Electrophysiologicalprinciples,6 TheoriginofECGmorphology,6 4 ECGmachines:howtoperformandinterpretECG,19 5 NormalECGcharacteristics,21 Heartrate,21 Rhythm,21 PRintervalandsegment,21 QTinterval,23 Pwave,24 QRScomplex,24 STsegmentandTwave,24 AssessmentoftheQRSelectricalaxisinthefrontalplane,26 Rotationsoftheheart,26 Electrocardiographicchangeswithage,30 6 Electrocardiographicdiagnosticcriteria,32 7 Atrialabnormalities,35 Rightatrialenlargement,35 Leftatrialenlargement,35 Biatrialenlargement,37 Interatrialblock,37 8 Ventricularenlargement,39 Rightventricularenlargement,40 Electrocardiographicsignsofrightacuteoverload,44 Leftventricularenlargement,44 Biventricularenlargement,48 v P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 vi Contents 9 Ventricularblocks,50 Completerightbundlebranchblock(RBBB),53 Partialrightbundlebranchblock,55 Completeleftbundlebranchblock(LBBB),57 Partialleftbundlebranchblock,58 Zonal(divisional)leftventricularblock,58 Bifascicularblocks,59 Trifascicularblocks,60 10 Ventricularpre-excitation,61 WPW-typepre-excitation,61 ShortPRtypepre-excitation(Lown–Ganong–Levine syndrome),67 11 Electrocardiographicpatternofischaemia,injury andnecrosis,68 Anatomicintroduction,68 Electrophysiologicalintroduction,69 Electrocardiographicpatternofischaemia,73 Electrocardiographicpatternofinjury,80 Electrocardiographicpatternofnecrosis,97 12 Miscellaneous,117 ValueofECGinspecialconditions,117 ECGpatternofpoorprognosis,117 ECGofelectricalalternans,117 Self-assessment,121 References,165 Index,169 P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 18:58 Foreword BasicElectrocardiography:NormalandAbnormalECGPatternsisnotanadditional regulartextbookonelectrocardiography.ProfessorAntoniBaye´sdeLuna,the authorofthepresenttextbookisaworld-widerenownedelectrocardiographer and clinical cardiologist who has contributed to our knowledge and under- standingofelectrocardiologyovertheyears.Inthepresenttextbook,heshares withushisvastexperienceandknowledge,summarisingthetraditionalcon- ceptsofelectrocardiographyandvectrocardiographycombinedwithcurrent updatesonthemostrecentdevelopmentscorrelatingelectrocardiographicpat- terns with magnetic resonance imaging. This textbook is of particular value totheAmericanphysiciansandhealthcareproviders,asitexposesthereader to the Mexican, Argentinean and European schools of electrocardiography, whichsomeoftheearliertextbookshavetendedtooverlook. Thepresenttextbookprovidesaconcisesummaryoftheclassicalandmod- ernconceptsofelectrocardiologyandprovides22casescoveringawidespec- trum of normal variations and abnormal electrocardiographic findings. In thesecasesDr.Baye´sdeLunaexplainshisapproachforinterpretingtheelec- trocardiogramandintegratingitwiththeclinicalfindings. In conclusion, this textbook is an asset for every cardiologist, internist, primary care physician, as well as medical students and other healthcare providersinterestedinbroadeningtheirskillsinelectrocardiography. YochaiBirnbaum,MD EdwardD.andSallyM.FutchProfessorofMedicine BiochemistryandMolecularBiology MedicalDirector,CardiacIntensiveCareUnit MedicalDirector,theHeartStation TheDivisionofCardiology TheUniversityofTexasMedicalBranch vii P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna May1,2007 17:29 CHAPTER 1 Introduction Theelectrocardiogram(ECG),introducedintoclinicalpracticemorethan100 yearsagobyEinthoven,constitutesalinealrecordingoftheheart’selectrical activity that occurs successively over time. An atrial depolarisation wave (P wave), a ventricular depolarisation wave (QRS complex) and a ventricular repolarisationwave(Twave)aresuccessivelyrecordedforeachcardiaccycle (Figures 1A–C). As these different waves are recorded from different sites (leads)themorphologyvaries(Figure2).Nevertheless,thesequenceisalways P–QRS–T.AnECGcurverecordedfromanelectrodefacingtheleftventricleis showninFigure1D.Dependingontheheartrate,theintervalbetweenwaves ofonecycleandanotherisvariable. Other different forms of recording cardiac activity (vectorcardiography, bodymapping,etc.)exist[1].Vectorcardiography(VCG)representselectrical activitybydifferentloopsoriginatingfromtheunionoftheheadsofmultiple vectorsofatrialdepolarisation(Ploop),ventriculardepolarisation(QRSloop), andventricularrepolarisation(Tloop).AclosecorrelationexistsbetweenVCG loopsandtheECGcurve.Therefore,onemaydeductECGmorphologyonthe basis of the morphology of VCG loop and vice versa. This is due to loop– hemifieldcorrelationtheory(seep.10).Accordingtothiscorrelation(Figures 16,18and21),themorphologyofdifferentwaves(P,QRSandT)recordedfrom differentsides(leads)varies(Figure2).Astheheartisathree-dimensionalor- gan,projectionoftheloopswiththeirmaximumvectorsintwoplanes,frontal and horizontal, on the positive and the negative hemifield∗ of each lead is required to ascertain exactly the loop’s location and allow deducting ECG morphology(Figures3and4).ThemorphologyofECGdependsnotonlyon the maximum vector of a given loop butalso onitsrotation (Figure 4).This representstheimportanceofconsideringtheloopandnotonlyitsmaximum vectortoexplaintheECGmorphology. ∗Thepositiveandthenegativehemifieldofeachleadareobtainedbydrawinglines perpendiculartoeachlead,passingthroughthecentreoftheheart.Thepositivehemifield islocatedintheareaofpositivepartofthelead,andthenegativehemifieldinthenegative part.InFigure4thepositivehemifieldisthearealocatedbetween−90◦and+90◦passing through0◦,andthepositivehemifieldofleadVFisthearealocatedbetween0◦and180◦ passingthrough+90◦.Theotherpartoftheelectricalfieldcorrespondstothenegative hemifieldofeachlead(seep.10). 1 P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna May1,2007 17:29 2 Chapter1 A B 1 1 3 +1 3 +1 2 2 2 VF 1 3 C D +1 P T +1 QRS VF VF Figure1 Three-dimensionalperspectiveofthePloop(A),QRSloopwithitsthreerepresentative vectors(B)andTloop(C),andtheirprojectiononthefrontalplanewiththecorrelationloop–ECG morphology.(D)GlobalcorrelationbetweentheP,QRSandTloopsandECGmorphologyonthe frontalplanerecordedinaleadfacingtheleftventriclefreewall(leadI). A rS RS Rs QS R R slurred rSr´ rSR´ rsr’s´ Qr QR Q slurred R qR qRs qRS qrS Q slurred B Flat Peaked Bimodal Positive Negative Diphasic + − − + + − − + + − − + + − − + Isodiphasic Figure2 ThemostfrequentQRScomplexmorphologies(A),PandTwavesmorphologies(B). P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna May1,2007 17:29 Introduction 3 A B C D FP FP FP FP I I V 6 HP HP HP HP V V 1 2 Figure3 Aloopwithitsmaximumvectordirecteddownwards,totheleftandforwards(A)and anotherwithitsmaximumvectordirecteddownwards,totheleftandbackwards(B)havethesame projectionsonthefrontalplane(FP)butdifferentprojectionsonthehorizontalplane(HP).Onthe otherhand,aloopwiththemaximumvectordirectedupwards,totheleftandforwards(C)and anotherwiththemaximumvectordirecteddownwards,totheleftandforwards(D)producethe sameprojectionontheHP,butdifferentprojectionsontheFP. A B C A B B I I A B A VF VF VF Figure4 Ifthemaximumvectorofaloopfallsinthelimitofpositiveandnegativehemifieldsofa certainlead,anisodiphasicdeflectionisrecorded.However,accordingtothedirectionofloop rotationtheQRScomplexmaybepositive–negativeornegative–positive(seeexamplesforleads VFandIinthecaseofmaximumvectordirectedto0◦(B)and+90◦(C)).Theloopwithmaximum vectorat45◦(A)alwaysfailsinthepositivehemifieldofIandVF,independentlyofthesenseof rotation. VCGisrarelyusedincurrentclinicalpractice;however,itishighlyusefulin understandingECGmorphologiesandinteachingelectrocardiography.Later inthisbookwewillexplaininmoredetailhowtheloopsoriginateandhow theirprojectioninfrontalandhorizontalplanesexplainstheECGmorpholo- giesindifferentleads. P1:OTE/SPH P2:OTE BLUK096-BayesdeLuna June7,2007 19:0 CHAPTER 2 Usefulness and limitations of electrocardiography ECGisthetechniqueofchoiceinthestudyofpatientswithchestpain,syncope, palpitations and acute dyspnoea, and is crucial for the diagnosis of cardiac arrhythmias, conduction disturbances, pre-excitation syndromes and chan- nelopathies.Itisalsoveryimportantforassessingtheevolutionandresponse totreatmentofalltypesofheartdiseasesandotherdiseases,anddifferentsit- uationssuchaselectrolyticdisorders,drugadministration,athletes,surgical evaluation,etc.Additionally,itisusefulforepidemiologicstudiesandscreen- ing(check-up). Despiteitsinvaluableusefulnessifusedcorrectly,electrocardiographymay inducemistakesifoneexcessivelytrustsonanECGrecordingofnormalap- pearance.Sometimes,bowingtothe‘magical’powerofECG,physicianscaring forapatientwithchestpainofdoubtfuloriginmaystate:‘Let’shaveanECG recording done so that we may solve the problem’. It must be remembered thatahighpercentageofpatientswithcoronaryheartdisease,intheabsence ofchestpain,showanormalECGrecordingandthateveninacutecoronary syndromesECGisnormalorborderlineinapproximately5–10%ofcases,and without symptoms especially in its early phase. Furthermore, ECG may be normalmonthsoryearsafteramyocardialinfarction.Fromtheabove,itcan beinferredthatanormalECGdoesnotimplyany‘lifeinsurance’asapatient maydiefromcardiaccausesevenonthesamedayanormalrecordingistaken. However,itisevidentthatintheabsenceofclinicalfindingsorfamilyhistory ofsuddendeath,thepossibilityofthisoccurringis,infact,veryremote. On the other hand, on occasions some subtle ECG abnormalities with no evidence of heart disease may be observed. Clearly, in such cases one must becautious,andbeforeconsideringthistobeanon-specificabnormality,is- chaemicheartdisease,channelopathies(longQT,Brugada’ssyndrome,etc.)or pre-excitationsyndromesshouldberuledout.Therefore,itisnecessarytoread theECGrecordingswhilebearinginmindtheclinicalsettingand,ifnecessary, takingsequentialrecordings. Inaddition,normalvariantsmaybeobservedintheECGrecording,which arerelatedtoconstitutionalhabits,chestmalformations,age,etc.Eventran- sientabnormalitiesmaybedetectedowingtoanumberofcauses(hyperven- tilation,hypothermia,glucoseoralcoholintake,ionicabnormalities,effectof certaindrugs,etc.). Electrocardiography has become even more important than it was at the beginning. In the twenty-first century, ECG is not only a technique used to 4
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