起搏器介导的心动过速.ppt

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2024-11-30 发布于北京
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起搏器介导的心动过速.ppt

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PacemakerMediatedtachycardia(PMT)israreduetothespecialfunctionsofthepacemakersandthecareoftheimplantingcardiologists.PatientswhoexperiencePMTusuallyexhibitsymptomsofpalpitations,shortnessofbreath,chestpain,dizziness,nearsyncope,and/ornausea.Manyofthesepatientswouldneedtogototheirdoctor抯officeoranemergencyroomtohavetheirpacemakerreprogrammed.Thisisexpensive,timeconsumingandunnecessarywiththepacemakerfeatureswehavetoday.InpatientswithnormalAVconduction,VAconductionisintactapproximately70%ofthetime.However,itcanoccurinpatientswithnormalAVconduction.TheincidenceofVAconductionincreaseswhenthepatienthasAVnodaldisease.Theincidenceincreaseswiththedegreeofheartblock.AnyeventsthatcontributetothelossofAVsynchronymayincreasetheriskforPMT.LongAVDelays:thenextatrialsensedeventmayoccurtoocloselyafteraventricularpacedevent.IfthisatrialeventissensedrightafterthePVARP,anatrialTachycardiamaystart.PVC:Prematureventricularcontractionsarecloselyfollowedbytheatrialdepolarization(p-waves)thatdidnotoccurpriortotheventricularevent.Often,thesep-wavesaresensedandaAVintervalisstarted.ThisishowthePMTisinitiated.EarlyPACs:SameasabovebecausethestarttheAVinterval.SensedArtifactintheatrium:BecauseitwillstarttheAVintervalSamewithmyopotentialsThebestchoiceforpatientsatriskforthisproblemisprevention.However,ifaPMTdoesstarttherearefeaturesinourpacemakersthatwillinterruptthePMTwiththeintentofterminatingthetachycardia.ThekeytopreventionistomaintainareasonableAVintervalthatallowsforahighertrackingrate.Inotherwords,wewanttoincreasethe2:1blockingrate.Featuresthathelptoincreasethe2:1blockrateare:1)RA-AVDelaywhichwilldecreasetheAVintervalastheatrialrateincreases.