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Indications for Electrophysiological Testing

Samuel C. Dudley, Jr., M.D., Ph.D.Division of CardiologyDepartment of PhysiologyEmory University/Atlanta VAMC

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What EP testing can doWhat EP testing can do

l Measure conduction intervals– good for bradyarrhythmias

l Add extrastimuli– good for reentrant tachyarrhythmias

l Ablation– good for focal and reentrant tachycardias

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Conduction systemConduction system

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Measurements madeMeasurements made

l Recovery of automaticityl Conduction velocityl Refractorinessl Activation mappingl Pace mapping

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Mechanisms of arrhythmiaMechanisms of arrhythmial Automaticity

– normal (e.g. sinus tachycardia)– abnormal (e.g. reperfusion arrhythmias)

l Triggered activity– Early afterdepolarizations associated with QT

prolongation (torsades de pointes)– Delayed afterdepolarizations associated with Ca2+

overload (e.g. digoxin)l Reentry

– fixed obstruction (e.g. atrial flutter)– leading circle (e.g. ventricular fibrillation)

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Reentry Reentry -- initiationinitiation

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 183.

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Reentry Reentry -- response to response to extrastimulusextrastimulus

NothingNothing EntrainmentEntrainment TerminationTerminationJosephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 209.

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Triggered activityTriggered activity

EADs EADs -- Bradycardia DependentBradycardia Dependent DADs DADs -- Tachycardia DependentTachycardia Dependent

Wit and Rosen. 1992. In The Heart and Cardiovascular System, Ed. Fozzard et al. Raven Press.

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Responses of arrhythmias during PESResponses of arrhythmias during PES

NormalAutomaticity

AbnormalAutomaticity

EADs DADs Reentry

Initiated bydrive train

No No No Yes Yes

Initiated byextrastimuli

No No No Variable Yes

Suppresion byoverdrive

Yes, notermination

No, notermination

Yes Variable Rare, possibleentrainment

Terminationbyextrastimulus

No No Variable Unlikely Yes,termination ina range

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Problems addressed by EP studiesProblems addressed by EP studies

l Bradyarrhythmias (site of block)– Sinus node function– AV block– IVCD

l Tachyarrhythmias– SVT

• AV reentrant tachycardia• AV nodal reentry

– VT

l Syncopel Evaluate implanted

device programming options

l Evaluate efficacy of therapy

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Basic rulesBasic rules

l Always try to make an EKG diagnosis first.l Fix ischemia firstl If you cannot bring on the tachycardia, it is

hard to ablate it.– Think twice about starting drugs

l If the rhythm is not stable, it is hard to ablate it.

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When not to do EPSWhen not to do EPSl Symptoms correlating with

ECG findingsl Asymptomatic patients with

sinus slowing or Wenckebach during sleep only

l Asymptomatic bifascicularblock

l Asymptomatic preexcitation

l Congenital long QT and acquired long QT correlating with symptoms

l Asymptomatic patients without risk factors for SCD

l Patients with cardiac arrest within 48 hrs of ischemia/MI

l Cardiac arrest from other causes

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Complications (<2%)Complications (<2%)l Hemorrhagel Phlebitisl Thromboembolusl Arrhythmiasl Tamponadel CVA (Left sided procedures)l Pneumothoraxl RF ablation

– valve damage– AV block

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HRA

RV

CSHIS

RV

Catheters positionsCatheters positions

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Normal ElectrogramNormal Electrogram

His spike

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 98.

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Sinus node dysfunctionSinus node dysfunction

Prystowsky and Klein. 1994. Cardiac Arrhythmias. 307.

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AV blockAV block

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 101.

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AV BlockAV Blockl Type I 2° AVB or 3° AV block

with narrow QRS– AV node– rarely intra His

l Type I 2° AVB or 3° AV block wide QRS– anywhere

l Type II 2° AVB, wide QRS– infra His– intra His– AV node (rare)Josephson. 1993. Clinical Cardiac Electrophysiology 2nd

Edition. 110.

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HV intervals & HV intervals & bifascicularbifascicular blockblock

l HV > 55 ms high sensitivity but low specificity for progression (2-3%/yr CHB)

l Infra His block during atrial pacing has low sensitivity but high specificity

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 108.

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Induced monomorphic VT Induced monomorphic VT

Prystowsky and Klein. 1994. Cardiac Arrhythmias. 313.

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VT or SVT?VT or SVT?

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 422.

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MUSTT registryMUSTT registry

Bruxton et al. 1999. NEJM: 341, 1882.

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Rhythms managed by RF ablationRhythms managed by RF ablationl PSVT (i.e. AV reentry) - success > 90%l Wolff-Parkinson-Whitel Atrial flutterl VT

– 1º for idiopathic VT - success 85%– 2 º for monomorphic VT associated with heart disease -

success 50-60%l Ectopic atrial tachycardias - success 75%l Sinus node reentry or inappropriate tachycardial Atrial fibrillation - His bundle vs. maze

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SVT ablationSVT ablation

SVT SVT -- Long RPLong RP

Post ablationPost ablation

Pre ablationPre ablation

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Mapping WPWMapping WPW

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 347.

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SVT ablationSVT ablation

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 743.

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AV nodal reentryAV nodal reentry

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Mapping SVTMapping SVT

Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 188.

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Ablating SVT Ablating SVT -- Triangle of KochTriangle of Koch

Coronary os

Tricuspid annulus

Compact AV nodeTendon of todaroCrista terminalis

IVC os Slow pathwaySlow pathway

Fast Pathway