ECG-英文课件-完美版

ECGTHEFIRSTAFFILIATEDHOSPITALOFDALIANMEDICALUNIVERSITYShaokeMeng•Clinicaldiagnosisdependsmainlyonapatient’shistory,andtoalesserextentonthephysicalexamination；•ItisimportanttoseetheECGasatool,andnotasanendinitself；•MostlyECGcanprovideevidencetosupportadiagnosis,however，insomecasesitiscrucialforpatientmanagement.Electrocardiogram(ECG)•Basicknowledge•Measurements&NormalrangesinECG•Atrialenlargement&ventricularhypertrophy•MyocardialInfarction•arrhythmiaChapter1basicknowledgeDefinition•Electronicpulseisproducedbeforeeverycorrespondingmechanicalsystoleatheart.•Electrocardiogramisafluctuatecurverecordedbiologicalelectricitythroughbodysurfacebyelectrocardiograph。Electrocardiographytheory•Theelectrocardiosignaloflivingcelliscomefromthecytomembrane’sselectivepermeationtochargedionsuchas:K+、Na+、C1－、Ca2＋.Andthoseion’sone-directionmobility.•Myocardiumstaysinrest.•Positiveionlaysoutsidethecytomembrane,meanwhileequivalentnegativeionlaysinsidethecytomembrane.•Thiskindofionarrayissocalledpolarization.Stimulatedmyocardiumrapidlychangeits“outsidepositive,insidenegative”stateinto“outsidenegative,insidepositive”state.TheprocedureofpolarizationreverseissocalledDepolarization.ElectrocardiographytheorystimulatedmyocardiumdepolarizationbeginningfromlefttorightThefirsthalfofthefiberhasalreadydepolarized,whiletheremaininghalfisstillpolarized.Thereforetheleftelectrodeontheoutsideofthefiberisinanareaofnegativity,andtherightelectrodeisinanareaofpositivity,whichcausesthemetertorecordpositively.Totherightofthemusclefiberisshownarecordofchangesinpotentialbetweenthetwoelectrodes,asrecordedbyahigh-speedrecordingmeter.Theproceduremyocardiumrestorepolarizationafterdepolarizebymultipleionre-distributingandenergyconsumingmodulationofionpump,issocalledRepolarization.•FigureCshowshalfwayrepolarizationofthesamemusclefiber,withpositivityreturningtotheoutsideofthefiber.Atthispoint,theleftelectrodeisinanareaofpositivity,andtherightelectrodeisinanareaofnegativity.•Thispolarityisoppositetothepolarityoccurredindepolarization.Consequently,therecording,asshowntotheright,becomesnegative.ElectrocardiographytheoryActionpotential•ThelowerhalfofFigureshowsasimultaneousrecordingoftheECGfromthissameventricle.•NoteespeciallythatnopotentialisrecordedintheECGwhentheventricularmuscleiseithercompletelypolarizedorcompletelydepolarized.Onlywhenthemuscleispartlypolarizedandpartlydepolarizeddoescurrentflowfromonepartoftheventriclestoanotherpart,andthereforecurrentalsoflowstothesurfaceofthebodytoproducetheECG.•Thetwoprocedureofdepolarizeandrepolarizecomposeadistinguishablemyocardiumpotentialchange.•Agroupoffluctuatecurvecanbeseenifrecorded,andthat’swhatwecalledactionpotentialcurveforonecardiacmyocyte.TheconceptionofVector•Thequantumwithmagnitudeanddirectioniscalledvector.•Thereispotentialdifferenceandlocalcurrentbetweendepolarized(polarized)regionandpolarized(depolarized)regiononthesurfaceofcytomembrane.•Thecurrentsflowsinacertaindirectionalongwiththedepolarization(polarization)propagates,sotheprocedureofdepolarization(polarization)canbeseenasamovementofaquantumwithmagnitudeanddirection,andthisquantumissocalledelectrocardialvector.•Thevectorcanberepresentbyaarrow“→”:arrowheadpointatthepositivepoleandthetailofarrowrepresentthenegativepole,thelengthofshaftshowsthemagnitudeofthevector.TheconceptionofVector•Instantaneoussyntheticvectorrepresentthetotalpotentialactivityofnumerousmyocardiumatsametime.•Bothatriumandventricle’sinstantaneousdepolarization(repolarization)hasitscorrespondsyntheticvector,namedP、Ta、QRS、Tvectorrespectively,representingtheinstantaneoussyntheticvectorwithmagnitudeanddirectionproducedbyatriumorventricledepolarization.Thepotentialintensityandwaveshapeofmyocardium•thequantityofmyocardium•thepositionofelectrodeanditsdistancetomyocardium•theanglebetweenelectrodeanddepolarizedirection•Theheartiscomposedofthreemajortypesofcardiacmuscle:atrialmuscle,ventricularmuscle,andspecializedexcitatoryandconductivemusclefibers.•Sinoatrialnode,SA:originationofnormalimpulse•Internodaltracts(atrialmuscle)•Atrioventricularnode,AV:adelayabout0.05~0.07s•Hisbundle•Right&LeftHisbranches•PurkinjefiberCardiacpacingandconductionsystemCardiacpacing&conductionsystem•Theelectricaldischargeforeachcardiaccyclenormallystartsinaspecialareaoftherightatriumcalledthe‘sinoatrial(SA)node’.•Depolarizationthenspreadsthroughtheatrialmusclefibres.•Thereisadelaywhiledepolarizationspreadsthroughanotherspecialareaintheatrium,the‘atrioventricularnode’(alsocalledthe‘AVnode’,orsometimesjust‘thenode’).•Thereafter,thedepolarizationwavetravelsveryrapidlydownspecializedconductiontissue,the‘bundleofHis’,whichdividesintheseptumbetweentheventriclesintorightandleftbundlebranches.•Theleftbundlebranchitselfdividesintotwo.•Withinthemassofventricularmuscle,conductionspreadssomewhatmoreslowly,throughspecializedtissuecalled‘Purkinjefibres’.•ElectricalactivationoftheheartcansometimesbegininplacesotherthantheSAnode.•Theword‘rhythm’isusedtorefertothepartoftheheartwhichiscontrollingtheactivationsequence.•Thenormalheartrhyt