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.