Download Indications for Electrophysiological Testing

Indications for Electrophysiological Testing
Samuel C. Dudley, Jr., M.D., Ph.D.
Division of Cardiology
Department of Physiology
Emory University/Atlanta VAMC
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What 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 system
3
Measurements made
l
Recovery of automaticity
l Conduction velocity
l Refractoriness
l Activation mapping
l Pace mapping
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Mechanisms of arrhythmia
l
l
l
Automaticity
– normal (e.g. sinus tachycardia)
– abnormal (e.g. reperfusion arrhythmias)
Triggered activity
– Early afterdepolarizations associated with QT
prolongation (torsades de pointes)
– Delayed afterdepolarizations associated with Ca2+
overload (e.g. digoxin)
Reentry
– fixed obstruction (e.g. atrial flutter)
– leading circle (e.g. ventricular fibrillation)
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Reentry - initiation
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 183.
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Reentry - response to extrastimulus
Nothing
Entrainment
Termination
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 209.
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Triggered activity
EADs - Bradycardia Dependent
DADs - Tachycardia 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 PES
Normal
Automaticity
Abnormal
Automaticity
EADs
DADs
Reentry
Initiated by
drive train
No
No
No
Yes
Yes
Initiated by
extrastimuli
No
No
No
Variable
Yes
Suppresion by Yes, no
overdrive
termination
No, no
termination
Yes
Variable
Rare, possible
entrainment
Termination
by
extrastimulus
No
Variable
Unlikely
Yes,
termination in
a range
No
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Problems addressed by EP studies
l
Bradyarrhythmias (site
of block)
– Sinus node function
– AV block
– IVCD
l
Tachyarrhythmias
l
l
l
Syncope
Evaluate implanted
device programming
options
Evaluate efficacy of
therapy
– SVT
• AV reentrant tachycardia
• AV nodal reentry
– VT
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Basic rules
l
Always try to make an EKG diagnosis first.
l Fix ischemia first
l 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 EPS
l
l
l
l
Symptoms correlating with
ECG findings
Asymptomatic patients with
sinus slowing or
Wenckebach during sleep
only
Asymptomatic bifascicular
block
Asymptomatic preexcitation
l
l
l
l
Congenital long QT and
acquired long QT
correlating with symptoms
Asymptomatic patients
without risk factors for SCD
Patients with cardiac arrest
within 48 hrs of ischemia/MI
Cardiac arrest from other
causes
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Complications (<2%)
l
l
l
l
l
l
l
l
Hemorrhage
Phlebitis
Thromboembolus
Arrhythmias
Tamponade
CVA (Left sided procedures)
Pneumothorax
RF ablation
– valve damage
– AV block
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Catheters positions
HRA
CS
HIS
RV
RV
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Normal Electrogram
Josephson. 1993. Clinical
Cardiac Electrophysiology
2nd Edition. 98.
His spike
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Sinus node dysfunction
Prystowsky and Klein. 1994. Cardiac Arrhythmias. 307.
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AV block
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 101.
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AV Block
l
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
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd
Edition. 110.
Type II 2° AVB, wide QRS
– infra His
– intra His
– AV node (rare)
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HV intervals & bifascicular block
l
l
Josephson. 1993. Clinical Cardiac
Electrophysiology 2nd Edition. 108.
HV > 55 ms high
sensitivity but low
specificity for
progression (2-3%/yr
CHB)
Infra His block during
atrial pacing has low
sensitivity but high
specificity
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Induced monomorphic VT
Prystowsky and Klein. 1994. Cardiac Arrhythmias. 313.
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VT or SVT?
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 422.
21
MUSTT registry
Bruxton et al. 1999.
NEJM: 341, 1882.
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Rhythms managed by RF ablation
l
l
l
l
l
l
l
PSVT (i.e. AV reentry) - success > 90%
Wolff-Parkinson-White
Atrial flutter
VT
– 1º for idiopathic VT - success 85%
– 2 º for monomorphic VT associated with heart disease success 50-60%
Ectopic atrial tachycardias - success 75%
Sinus node reentry or inappropriate tachycardia
Atrial fibrillation - His bundle vs. maze
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SVT ablation
Pre ablation
SVT - Long RP
Post ablation
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Mapping WPW
Josephson. 1993.
Clinical Cardiac
Electrophysiology 2nd
Edition. 347.
25
SVT ablation
Josephson. 1993.
Clinical Cardiac
Electrophysiology 2nd
Edition. 743.
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AV nodal reentry
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Mapping SVT
Josephson. 1993. Clinical Cardiac Electrophysiology 2nd Edition. 188.
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Ablating SVT - Triangle of Koch
Fast Pathway
Crista terminalis
Tendon of todaro
Compact AV node
Tricuspid annulus
Coronary os
IVC os Slow pathway
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