室性心动过速消融何时进行？消融？WinKShen课件

WinK.Shen,M.D.ProfessorofMedicineMayoClinicCollegeofMedicineGW-HRSJointSymposium,Beijing2009CP1063458-1室性心动过速的消融：

何时进行？如何消融？?WinK.Shen,M.D.CP1063458-1室性声明RelevantFinancialRelationship(s)NoneOffLabelUsageNone声明RelevantFinancialRelations室性心动过速的机制折返、拖带、隐匿性拖带的基本概念稳定的，单形性室速不稳定或多折返环室速高级方法和技术内容室性心动过速的机制内容CP1323528-2室速消融指南建议I类适应证持续单形性室速，药物无效或不能耐受或患者不愿意长期服药，猝死低危患者(C)束支折返室速(C)ICD植入后反复放电，重新程控、调整用药均无效，或不愿意接受长期药物治疗的患者，导管消融作为辅助治疗(C)Circ2006CP1323528-2室速消融I类适应证Circ2006室性心律失常CP1206111-1“局灶”“多发性”流出道分支瓣上RVLV普肯野折返解剖靶点心肌病疤痕二尖瓣电生理策略P.刺激拖带影像电生理损伤解剖室性心律失常CP1206111-1“局灶”“多发性”流出道分室速标测和消融步骤潜在的心脏机制，病史缺血性心脏病特发性扩心病其它根据心电图判断心动过速的起源程序性刺激，方法重整拖带隐匿性拖带高级标测技术电压标测电解剖标测影像心外膜标测其它室速标测和消融步骤潜在的心脏机制，病史标测的概念折返性室速双电位疤痕Scars0.5mV2mV潜在折返环CP1176527-5标测的概念折返性室速双电位疤痕Scars0.5mV2mVCP1233975-13ECGECGQRS起始共同通路(CP)CP

入口内环疤痕外环疤痕通道盲端CP出口折返环和相关术语CP1233975-13ECGECGQRS起始共同通路(CP该室速折返环出口位置可能是:A.LV/前壁/基底部/侧壁B.LV/后壁/心尖/侧壁C.LV/后壁中部/间隔部D.LV/后壁/心尖/间隔部该室速折返环出口位置可能是:标测示意图横断面基地部心尖长轴切面间隔侧壁12693前壁后壁CP1060083-4ABCDE标测示意图横断面基地部心尖长轴切面间隔侧壁12693前壁后壁QRS形态提示室速的出口位置V4基底部心尖AVRCP1060083-1AVRV4QRS形态提示室速的出口位置V4基底部心尖AVRCP1060II,III,aVFQRS形态提示室速的出口CP1060083-2前壁后壁II,III,aVFII,III,aVFQRS形态提示室速的出口CP106QRS形态提示室速的出口I,aVL间隔部侧壁II,III,aVFCP1060083-3QRS形态提示室速的出口I,aVL间隔部侧壁II,III该室速的折返环出口位置可能是:A.LV/前壁/基底部/侧壁B.LV/后壁/心尖/侧壁C.LV/后壁/中部/间隔部D.LV/后壁/心尖l/间隔**该室速的折返环出口位置可能是:**CP1233975-13折返环路与拖带A,B,C拖带，隐匿融合PPI=VTCLS-QRS=EGM-QRSS-QRS<70%VTCLD,E*拖带，隐匿融合PPI>VTCLS-QRS>EGM-QRSF拖带，显性融合PPI=VTCLS-QRS=EGM-QRSG拖带，显性融合PPI≠VTCLS-QRS≠

EGM-QRSABCDE*FGCP1233975-13折返环路与拖带A,B,CABCD起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获ABCD哪个位置起搏与折返环有关?起搏部位:ABCD哪个位置起搏与折返环有关?起搏部位缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获*起搏部位*起搏部位：缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获ABCD起搏部位：ABCD起搏部位缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获*起搏部位*起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获PPITCLABCDPPI=395S-QRS=265VTCL=395E-QRS=265起搏部位:PPITCLABCDPPI=395S-QRS起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获PPITCL*PPI=395S-QRS=265VTCL=395E-QRS=265起搏部位:PPITCL*PPI=395S-QRS=2室速终止CP1201033-1%0-10n=4611-30n=1831-60n=24>60n=64PPI-VTCL(msec)室速终止CP1201033-1%0-10n=4611-30nCP1270284-4VT#5VT1VT2VT3VT3CP1270284-4VT#5VT1VT2VT3VTCP1270284-17电压标测指导的室速消融CP1270284-17电压标测指导的室速消融男性，55岁，扩张型心肌病,EF27%

ICD频繁放电，既往消融失败男性，55岁，扩张型心肌病,EF27%

ICD频繁放电左心室辅助装置Low-speedcentrifugalcontinuousflowpumpLowbloodsurfaceareacontact21FrLeftatrialcannula19FrfemoralarterialcannulaUpto4L/minFlowThieleetalCirc2001左心室辅助装置Low-speedcentrifugalc左心室支持下诱发室速左心室支持下诱发室速左心室辅助支持下心内膜及心外膜标测LAALACannulaEndoEpi左心室辅助支持下心内膜及心外膜标测LAALAEndoEpi经心外膜途径消融Schweikertetal.Circulation.2003;108:1329-1335.EduardoSosa,JACC2000室速合并冠心病的患者经心外膜消融是可行的.53例中发生了4例右心室穿孔及心脏压塞

对其它心律失常亦有效(VT伴或不伴SHD,WPW,RVOTVT,AT)

，尤其是经心内膜消融失败的患者无并发症报道经心外膜途径消融Schweikertetal.Circ左心室心内膜和心内膜消融MitralValve左心室心内膜和心内膜消融MitralValve多数情况下为折返机制根据拖带的反应识别传导的关键区域多形性室速和多环路折返较常见通常需要电压/把横标测部分病人可能需要心外膜标测为防止ICD反复放电，多数患者应接受姑息性VT消融疤痕依赖基质的室速消融多数情况下为折返机制疤痕依赖基质的室速消融GW-ICCHRSJointSymposiumBeijingOct.11,2009GW-ICCHRSJointSymposiumBeijWinK.Shen,M.D.ProfessorofMedicineMayoClinicCollegeofMedicineGW-HRSJointSymposium,Beijing2009CP1063458-1VentricularTachycardiaAblation

WhenandHow?WinK.Shen,M.D.CP1063458-1VeDISCLOSURERelevantFinancialRelationship(s)NoneOffLabelUsageNoneDISCLOSURERelevantFinancialRSpectrumofVTmechanismsBasicconceptofreentry,entrainment,andconcealedentrainmentStable,monomorphicVTUnstableVTormultiplecircuitsAdvancedtechnologyandtechniquesObjectivesSpectrumofVTmechanismsObjecCP1323528-2VTAblationRecommendationsClassIAblationisindicatedinpatientswhoareotherwiseatlowriskforSCDandhavesustainedpredominantlymonomorphicVTthatisdrugresistant,whoaredrugintolerant,orwhodonotwishlong-termdrugtherapy(levelofevidence:C)Ablationisindicatedinpatientswithbundle-branchreentrantVT(levelofevidence:C)AblationisindicatedasadjunctivetherapyinpatientswithanICDwhoarereceivingmultipleshocksasaresultofsustainedVTthatisnotmanageablebyreprogrammingorchangingdrugtherapyorwhodonotwishlong-termdrugtherapy(levelofevidence:C)Circ2006CP1323528-2VTAblationClassICVentricularArrhythmiasCP1206111-1“Focal”“Diffuse”OutflowtractFascicularSupra-valvularRVLVPurkinjeReentryAnatomictargetMyopathicScarsMitralvalveEPmaneuversP.StimulationEntrainmentImagingElectrophysiologyLesioncreationAnatomyVentricularArrhythmiasCP12061StepsinMappingandAblatingVTUnderlyingcardiacsubstrate,historyIschemicheartdiseaseIdiopathicdilatedcardiomyopathyOthersECGrecognitionoftachycardiaoriginProgrammedstimulation,maneuversResetEntrainmentConcealedentrainmentAdvancedmappingVoltagemappingElectro-anatomicalcorrelationImagingEpicardialapproachOthersStepsinMappingandAblatingConceptsofMappingReentrantVentricularTachycardiaDoublepotentialsScarsScars0.5mV2mVPotentialcircuitsCP1176527-5ConceptsofMappingReentrantVCP1233975-13ECGECGQRSonsetCommonpathway(CP)CP

entranceInnerloopScarOuterloopScarDead-endpathwayCPexitReentrantCircuitandTerminologyCP1233975-13ECGECGQRSCommonpaThisVTcircuitexitsiteislikely:A.LV/anterior/basal/lateralB.LV/posterior/apical/lateralC.LV/posterior/mid/septalD.LV/posterior/apical/septalThisVTcircuitexitsiteislMappingSchemeCrossSectionBaseApexLongitudinalSectionSeptalLateral12693AnteriorPosteriorCP1060083-4ABCDEMappingSchemeCrossSectionBasQRSMorphologyCluestoVTExitSiteV4BaseApexAVRCP1060083-1AVRV4QRSMorphologyCluestoVTExiII,III,aVFQRSMorphologyCluestoVTExitSiteCP1060083-2AnteriorPosteriorII,III,aVFII,III,aVFQRSMorphologyCluQRSMorphologyCluestoVTExitSiteI,aVLSeptalLateralII,III,aVFCP1060083-3QRSMorphologyCluestoVTExiThisVTcircuitexitsiteislikely:A.LV/anterior/basal/lateralB.LV/posterior/apical/lateralC.LV/posterior/mid/septalD.LV/posterior/apical/septal**ThisVTcircuitexitsiteislCP1233975-13ReentrantCircuitandEntrainmentA,B,CEntrainmentwithconcealedfusionPPI=VTCLS-QRS=EGM-QRSS-QRS<70%VTCLD,E*EntrainmentwithconcealedfusionPPI>VTCLS-QRS>EGM-QRSFEntrainmentwithmanifestedfusionPPI=VTCLS-QRS=EGM-QRSGEntrainmentwithmanifestedfusionPPI≠VTCLS-QRS≠

EGM-QRSABCDE*FGCP1233975-13ReentrantCircuitPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncaptureABCDWherewasthepacingsiteinrelationshiptothecircuit?PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapture*PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncaptureABCDPacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapture*PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapturePPITCLABCDPPI=395S-QRS=265VTCL=395E-QRS=265PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapturePPITCL*PPI=395S-QRS=265VTCL=395E-QRS=265PacingatthissiteismostcoTerminationofVTCP1201033-1%0-10n=4611-30n=1831-60n=24>60n=64PPI-VTCL(msec)TerminationofVTCP1201033-1%0CP1270284-4VT#5VT1VT2VT3VT3CP1270284-4VT#5VT1VT2VT3VTCP1270284-17VoltageMapGuidedVTAblationCP1270284-17VoltageMapGuided55year-oldmanwithDCM,EF27%

FrequentICDshocks,failedpreviousablation55year-oldmanwithDCM,EF2LeftVentricularSupportLow-speedcentrifugalcontinuousflowpumpLowbloodsurfaceareacontact21FrLeftatrialcannula19FrfemoralarterialcannulaUpto4L/minFlowThieleetalCirc2001LeftVentricularSupportLow-spInductionofVTonLVSupportInductionofVTonLVSupportEndocardialandEpicardialMappingwithLeftVentricularSupportLAALACannulaEndoEpiEndocardialandEpicardialMapEpicardial

ApproachSchweikertetal.Circulation.2003;108:1329-1335.EduardoSosa,JACC2000EpicardialapproachshowntobefeasibleforVTablationinpatientswithCAD.Complicationseenin4/53patientsinformofRVperforationandtamponade.

Alsoeffectiveforotherarrhythmias(VTwith&withoutSHD,WPW,RVOTVT,AT)especiallywhenendocardialablationunsuccessful.NocomplicationsreportedEpicardial

ApproachSchweikertEndocardialandEpicardialLVAblationMitralValveEndocardialandEpicardialLVReentrymechanismismostcommonResponsetoentrainmentmaneuversdeterminesthecriticalzoneofconductionMultipleVTsandcircuitsarefrequentlypresentVoltage/scarmappingisoftenrequiredEpicardialapproachmayberequiredinselectedpatientsMostpatientsundergo“palliative”VTablationforrecurrentICDshocksVTAblationinScarDependentSubstrateReentrymechanismismostcommGW-ICCHRSJointSymposiumBeijingOct.11,2009GW-ICCHRSJointSymposiumBeijWinK.Shen,M.D.ProfessorofMedicineMayoClinicCollegeofMedicineGW-HRSJointSymposium,Beijing2009CP1063458-1室性心动过速的消融：

何时进行？如何消融？?WinK.Shen,M.D.CP1063458-1室性声明RelevantFinancialRelationship(s)NoneOffLabelUsageNone声明RelevantFinancialRelations室性心动过速的机制折返、拖带、隐匿性拖带的基本概念稳定的，单形性室速不稳定或多折返环室速高级方法和技术内容室性心动过速的机制内容CP1323528-2室速消融指南建议I类适应证持续单形性室速，药物无效或不能耐受或患者不愿意长期服药，猝死低危患者(C)束支折返室速(C)ICD植入后反复放电，重新程控、调整用药均无效，或不愿意接受长期药物治疗的患者，导管消融作为辅助治疗(C)Circ2006CP1323528-2室速消融I类适应证Circ2006室性心律失常CP1206111-1“局灶”“多发性”流出道分支瓣上RVLV普肯野折返解剖靶点心肌病疤痕二尖瓣电生理策略P.刺激拖带影像电生理损伤解剖室性心律失常CP1206111-1“局灶”“多发性”流出道分室速标测和消融步骤潜在的心脏机制，病史缺血性心脏病特发性扩心病其它根据心电图判断心动过速的起源程序性刺激，方法重整拖带隐匿性拖带高级标测技术电压标测电解剖标测影像心外膜标测其它室速标测和消融步骤潜在的心脏机制，病史标测的概念折返性室速双电位疤痕Scars0.5mV2mV潜在折返环CP1176527-5标测的概念折返性室速双电位疤痕Scars0.5mV2mVCP1233975-13ECGECGQRS起始共同通路(CP)CP

入口内环疤痕外环疤痕通道盲端CP出口折返环和相关术语CP1233975-13ECGECGQRS起始共同通路(CP该室速折返环出口位置可能是:A.LV/前壁/基底部/侧壁B.LV/后壁/心尖/侧壁C.LV/后壁中部/间隔部D.LV/后壁/心尖/间隔部该室速折返环出口位置可能是:标测示意图横断面基地部心尖长轴切面间隔侧壁12693前壁后壁CP1060083-4ABCDE标测示意图横断面基地部心尖长轴切面间隔侧壁12693前壁后壁QRS形态提示室速的出口位置V4基底部心尖AVRCP1060083-1AVRV4QRS形态提示室速的出口位置V4基底部心尖AVRCP1060II,III,aVFQRS形态提示室速的出口CP1060083-2前壁后壁II,III,aVFII,III,aVFQRS形态提示室速的出口CP106QRS形态提示室速的出口I,aVL间隔部侧壁II,III,aVFCP1060083-3QRS形态提示室速的出口I,aVL间隔部侧壁II,III该室速的折返环出口位置可能是:A.LV/前壁/基底部/侧壁B.LV/后壁/心尖/侧壁C.LV/后壁/中部/间隔部D.LV/后壁/心尖l/间隔**该室速的折返环出口位置可能是:**CP1233975-13折返环路与拖带A,B,C拖带，隐匿融合PPI=VTCLS-QRS=EGM-QRSS-QRS<70%VTCLD,E*拖带，隐匿融合PPI>VTCLS-QRS>EGM-QRSF拖带，显性融合PPI=VTCLS-QRS=EGM-QRSG拖带，显性融合PPI≠VTCLS-QRS≠

EGM-QRSABCDE*FGCP1233975-13折返环路与拖带A,B,CABCD起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获ABCD哪个位置起搏与折返环有关?起搏部位:ABCD哪个位置起搏与折返环有关?起搏部位缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获*起搏部位*起搏部位：缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获ABCD起搏部位：ABCD起搏部位缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获*起搏部位*起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获PPITCLABCDPPI=395S-QRS=265VTCL=395E-QRS=265起搏部位:PPITCLABCDPPI=395S-QRS起搏部位:缓慢传导的关键部位起搏在通道盲端起搏在外环起搏环外起搏无夺获PPITCL*PPI=395S-QRS=265VTCL=395E-QRS=265起搏部位:PPITCL*PPI=395S-QRS=2室速终止CP1201033-1%0-10n=4611-30n=1831-60n=24>60n=64PPI-VTCL(msec)室速终止CP1201033-1%0-10n=4611-30nCP1270284-4VT#5VT1VT2VT3VT3CP1270284-4VT#5VT1VT2VT3VTCP1270284-17电压标测指导的室速消融CP1270284-17电压标测指导的室速消融男性，55岁，扩张型心肌病,EF27%

ICD频繁放电，既往消融失败男性，55岁，扩张型心肌病,EF27%

ICD频繁放电左心室辅助装置Low-speedcentrifugalcontinuousflowpumpLowbloodsurfaceareacontact21FrLeftatrialcannula19FrfemoralarterialcannulaUpto4L/minFlowThieleetalCirc2001左心室辅助装置Low-speedcentrifugalc左心室支持下诱发室速左心室支持下诱发室速左心室辅助支持下心内膜及心外膜标测LAALACannulaEndoEpi左心室辅助支持下心内膜及心外膜标测LAALAEndoEpi经心外膜途径消融Schweikertetal.Circulation.2003;108:1329-1335.EduardoSosa,JACC2000室速合并冠心病的患者经心外膜消融是可行的.53例中发生了4例右心室穿孔及心脏压塞

对其它心律失常亦有效(VT伴或不伴SHD,WPW,RVOTVT,AT)

，尤其是经心内膜消融失败的患者无并发症报道经心外膜途径消融Schweikertetal.Circ左心室心内膜和心内膜消融MitralValve左心室心内膜和心内膜消融MitralValve多数情况下为折返机制根据拖带的反应识别传导的关键区域多形性室速和多环路折返较常见通常需要电压/把横标测部分病人可能需要心外膜标测为防止ICD反复放电，多数患者应接受姑息性VT消融疤痕依赖基质的室速消融多数情况下为折返机制疤痕依赖基质的室速消融GW-ICCHRSJointSymposiumBeijingOct.11,2009GW-ICCHRSJointSymposiumBeijWinK.Shen,M.D.ProfessorofMedicineMayoClinicCollegeofMedicineGW-HRSJointSymposium,Beijing2009CP1063458-1VentricularTachycardiaAblation

WhenandHow?WinK.Shen,M.D.CP1063458-1VeDISCLOSURERelevantFinancialRelationship(s)NoneOffLabelUsageNoneDISCLOSURERelevantFinancialRSpectrumofVTmechanismsBasicconceptofreentry,entrainment,andconcealedentrainmentStable,monomorphicVTUnstableVTormultiplecircuitsAdvancedtechnologyandtechniquesObjectivesSpectrumofVTmechanismsObjecCP1323528-2VTAblationRecommendationsClassIAblationisindicatedinpatientswhoareotherwiseatlowriskforSCDandhavesustainedpredominantlymonomorphicVTthatisdrugresistant,whoaredrugintolerant,orwhodonotwishlong-termdrugtherapy(levelofevidence:C)Ablationisindicatedinpatientswithbundle-branchreentrantVT(levelofevidence:C)AblationisindicatedasadjunctivetherapyinpatientswithanICDwhoarereceivingmultipleshocksasaresultofsustainedVTthatisnotmanageablebyreprogrammingorchangingdrugtherapyorwhodonotwishlong-termdrugtherapy(levelofevidence:C)Circ2006CP1323528-2VTAblationClassICVentricularArrhythmiasCP1206111-1“Focal”“Diffuse”OutflowtractFascicularSupra-valvularRVLVPurkinjeReentryAnatomictargetMyopathicScarsMitralvalveEPmaneuversP.StimulationEntrainmentImagingElectrophysiologyLesioncreationAnatomyVentricularArrhythmiasCP12061StepsinMappingandAblatingVTUnderlyingcardiacsubstrate,historyIschemicheartdiseaseIdiopathicdilatedcardiomyopathyOthersECGrecognitionoftachycardiaoriginProgrammedstimulation,maneuversResetEntrainmentConcealedentrainmentAdvancedmappingVoltagemappingElectro-anatomicalcorrelationImagingEpicardialapproachOthersStepsinMappingandAblatingConceptsofMappingReentrantVentricularTachycardiaDoublepotentialsScarsScars0.5mV2mVPotentialcircuitsCP1176527-5ConceptsofMappingReentrantVCP1233975-13ECGECGQRSonsetCommonpathway(CP)CP

entranceInnerloopScarOuterloopScarDead-endpathwayCPexitReentrantCircuitandTerminologyCP1233975-13ECGECGQRSCommonpaThisVTcircuitexitsiteislikely:A.LV/anterior/basal/lateralB.LV/posterior/apical/lateralC.LV/posterior/mid/septalD.LV/posterior/apical/septalThisVTcircuitexitsiteislMappingSchemeCrossSectionBaseApexLongitudinalSectionSeptalLateral12693AnteriorPosteriorCP1060083-4ABCDEMappingSchemeCrossSectionBasQRSMorphologyCluestoVTExitSiteV4BaseApexAVRCP1060083-1AVRV4QRSMorphologyCluestoVTExiII,III,aVFQRSMorphologyCluestoVTExitSiteCP1060083-2AnteriorPosteriorII,III,aVFII,III,aVFQRSMorphologyCluQRSMorphologyCluestoVTExitSiteI,aVLSeptalLateralII,III,aVFCP1060083-3QRSMorphologyCluestoVTExiThisVTcircuitexitsiteislikely:A.LV/anterior/basal/lateralB.LV/posterior/apical/lateralC.LV/posterior/mid/septalD.LV/posterior/apical/septal**ThisVTcircuitexitsiteislCP1233975-13ReentrantCircuitandEntrainmentA,B,CEntrainmentwithconcealedfusionPPI=VTCLS-QRS=EGM-QRSS-QRS<70%VTCLD,E*EntrainmentwithconcealedfusionPPI>VTCLS-QRS>EGM-QRSFEntrainmentwithmanifestedfusionPPI=VTCLS-QRS=EGM-QRSGEntrainmentwithmanifestedfusionPPI≠VTCLS-QRS≠

EGM-QRSABCDE*FGCP1233975-13ReentrantCircuitPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncaptureABCDWherewasthepacingsiteinrelationshiptothecircuit?PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapture*PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncaptureABCDPacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapture*PacingatthissiteismostcoPacingatthissiteismostconsistentwith:PacinginacriticalzoneofslowconductionPacingina“deadendalley”PacinginanouterloopPacingoutsideofthecircuitNoncapturePPITCLABCDPPI=395S-QRS=265VTCL=395E-QRS=265Pacing