Case 1:
A 57 year-old man without known cardiac disease presented with a wide
complex tachycardia (WCT) at a rate of 270 bpm requiring external
cardioversion. Cardiac magnetic resonance imaging (MRI) revealed a
mildly dilated LV and low-normal LV systolic function. Further
evaluation showed no evidence of myocardial ischemia or arrhythmia on
exercise stress testing.
At EPS, no arrhythmia was inducible despite burst and extra stimulus
pacing from the RA, RVA, and RVOT. PES included up to 3 extrastimuli to
a minimum coupling interval of 180 ms following two drive cycle lengths
with and without isoproterenol (up to 12 mcg/min eliciting sinus
tachycardia of 140 bpm). An RV voltage map identified a very small area
of low bipolar voltage (<1.5 mv) at the basal inferolateral RV
raising concern for arrhythmogenic RV cardiomyopathy. Pericardial access
was obtained and epicardial mapping revealed an extensive area of low
voltage (<1.5mV, Figure 1). PES was then performed from the RV
epicardium with 3 extrastimuli following a drive train of 350ms which
reproducibly induced sustained monomorphic VT (cycle length 235ms) that
was terminated with burst pacing. Following combined endocardial and
epicardial ablation targeting the low voltage substrate, VT was no
longer inducible with up to 3 extrasimuli from either the RV endocardium
or epicardium.