室性心律失常EP综述（英文版） .ppt
An Electrophysiologic Overview,Ventricular Tachyarrhythmias,Module Objectives Ventricular Tachyarrhythmias,Identify the mechanisms for ventricular tachycardiasDifferentiate types of ventricular tachycardias using ECG and intracardiac electrogram recordingsDiscuss treatment options for ventricular tachycardias,After completion of this module,the participant should be able to:,Module Outline Ventricular Tachyarrhythmias,DescriptionCharacteristicsMechanismsSustained vs.nonsustainedPremature ventricular contractions,Module Outline Ventricular Tachyarrhythmias,ClassificationMonomorphicIdiopathicDescriptionECG recognitionTreatment ablationBundle branchDescriptionECG recognitionTreatment ablation,Module Outline Ventricular Tachyarrhythmias,Classifications-continuedVentricular flutterECG recognitionVentricular fibrillationECG recognitionPolymorphicTorsades de pointesDescriptionECG recognitionTreatmentSummary,Ventricular Tachycardia(VT),Originates in the ventricles Can be life threateningMost patients have significant heart diseaseCoronary artery diseaseA previous myocardial infarctionCardiomyopathy,Mechanisms of VT,Reentrant Reentry circuit(fast and slow pathway)is confined to the ventricles and/or bundle branchesAutomatic Automatic focus occurs within the ventriclesTriggered activityEarly afterdepolarizations(phase 3)Delayed afterdepolarizations(phase 4),Reentrant,Reentrant ventricular arrhythmiasPremature ventricular complexesIdiopathic left ventricular tachycardiaBundle branch reentryVentricular tachycardia and fibrillation when associated with chronic heart disease:Previous myocardial infarctionCardiomyopathy,Automatic,Automatic ventricular arrhythmiasPremature ventricular complexesIschemic ventricular tachycardiaVentricular tachycardia and fibrillation when associated with acute medical conditions:Acute myocardial infarction or ischemiaElectrolyte and acid-base disturbances,hypoxemiaIncreased sympathetic tone,Automaticity,Abnormal Acceleration of Phase 4,Fogoros:Electrophysiologic Testing.3rd ed.Blackwell Scientific 1999;16.,Triggered,Triggered activity ventricular arrhythmiasPause-dependent triggered activityEarly afterdepolarization(phase 3)Polymorphic ventricular tachycardiaCatechol-dependent triggered activityLate afterdepolarizations(phase 4)Idiopathic right ventricular tachycardia,Triggered,Fogoros:Electrophysiologic Testing.3rd ed.Blackwell Scientific 1999;158.,Sustained vs.Nonsustained,Sustained VTEpisodes last at least 30 secondsCommonly seen in adults with prior:Myocardial infarctionChronic coronary artery diseaseDilated cardiomyopathy Non-sustained VTEpisodes last at least 6 beats but 30 seconds,Premature Ventricular Contraction,PVCEctopic beat in the ventricle that can occur singly or in clustersCaused by electrical irritabilityFactors influencing electrical irritabilityIschemiaElectrolyte imbalancesDrug intoxication,Classification,Ventricular TachycardiaMonomorphicIdiopathic VT Bundle branch reentry tachycardiaVentricular flutterVentricular fibrillationPolymorphicTorsades de pointes(TdP),Monomorphic VTs,Monomorphic VT,Heart rate:100 bpm or greaterRhythm:RegularMechanismReentryAbnormal automaticityTriggered activityRecognitionBroad QRSStable and uniform beat-to-beat appearance,ECG Recognition,ECG used with permission of Dr.Brian Olshansky.,Intracardiac Recording of VT,EGM used with permission of Texas Cardiac Arrhythmia,P.A.,Idiopathic Right Ventricular Tachycardia,Right ventricular idiopathic VTFocus originates within the right ventricular outflow tractVentricular function is usually normalUsually LBBB,inferior axisTreatment options:Pharmacologic therapy(beta blockers,verapamil)RF ablation,Kay NG.Am J Med 1996;100:344-356.,ECG Recognition,Case History:Idiopathic VT,First episode9 hours of palpitationsIn ER,found to be in wide-complex tachycardia of LBBB,inferior axis,at 205 bpmConverted with IV lidocaine;placed on tenorminSecond episodeWhile on tenormin,patient had onset of palpitations at airportIn ER,converted with IV lidocainePatient underwent EP study,39 y.o.female with no prior cardiac history,Case History:Idiopathic VT,Case History:Idiopathic VT,At EP study,tachycardia focus was mapped and localized to right ventricular outflow tractThe focus was successfully ablatedusing radiofrequency energy,with no subsequent inducible or clinical VT,Endocardial Activation Mapping,Using an ablation catheter,map the area around and inside of the right ventricular outflow tractFind the electrograms that precede the onset of the QRS complex during tachycardiaThis area identifies the site of earliest activation,and possibly the“site of origin”of the arrhythmia,Pace Mapping,Pace mapping helps to localize the“site of origin”after endocardial mapping has been performedIf the heart is paced from this region,the resulting ECG should be identical to the ECG taken during tachycardiaDelivering RF energy to this site usually eliminates ventricular tachycardia,Idiopathic VT Ablation in RVOT,RAO,RAO,Idiopathic Left Ventricular Tachycardia,RBBB/LAFBInvolves the Purkinje networkTreatment options:RF ablationPharmacologic therapy(verapamil,beta blockers),ECG used with permission of Kay NG.,ECG Recognition,Bundle Branch Reentry,Reentry circuit is confined to the left and right bundle branchesUsually LBBB,during sinus rhythmPresents with:SyncopePalpitationsSudden cardiac deathTreatment:RF ablation of right bundle,VT Due to Bundle Branch Reentry,Catheter Ablation of Right Bundle Branch,Courtesy of Dr.Warren Jackman,I,II,V1,RA,Current,Voltage,Ventricular Flutter,Heart rate:300 bpmRhythm:Regular and uniformMechanism:ReentryRecognition:No isoelectric intervalNo visible T waveDegenerates to ventricular fibrillationTreatment:Cardioversion,Ventricular Fibrillation,Heart rate:Chaotic,random and asynchronousRhythm:IrregularMechanism:Multiple wavelets of reentryRecognition:No discrete QRS complexesTreatment:Defibrillation,ECG Recognition,P waves and QRS complexes not presentHeart rhythm highly irregularHeart rate not defined,Polymorphic VT,Polymorphic VT,Heart rate:VariableRhythm:IrregularMechanism:ReentryTriggered activityRecognition:Wide QRS with phasic variationTorsades de pointes,ECG Recognition,EGM used with permission of Texas Cardiac Arrhythmia,P.A.,Torsades de Pointes(TdP),Heart rate:200-250 bpmRhythm:IrregularRecognition:Long QT intervalWide QRSContinuously changing QRS morphology,Mechanism,Events leading to TdP are:HypokalemiaProlongation of the action potential durationEarly afterdepolarizationsCritically slow conduction that contributes to reentry,ECG Recognition,QRS morphology continuously changesComplexes alternates from positive to negative,Possible Causes,Drugs that lengthen the QT:QuinidineProcainamideSotalolIbutilidePhysicalIschemiaElectrolyte abnormalities,Treatment,Pharmacologic therapy:PotassiumMagnesiumIsoproterenolPossibly class Ib drugs(lidocaine)to decrease refractoriness/shorten length of action potentialOverdrive ventricular pacingCardioversion,Summary,VT ablation is not an FDA-approved indicationRF catheter ablation can be a useful technique in patients with ventricular tachycardiaSuccess largely depends on the etiology of the arrhythmiaUnstable sustained VT,polymorphic VT and ventricular fibrillation are not ablatableImproved catheters and imaging techniques may change this in the future,
