Case 4:
A 64 year old man with ischemic cardiomyopathy and recurrent VT despite
amiodarone, mexiletine and two prior ablation procedures presented for
repeat VT ablation. PES from the RV apex with up to three extrastimuli
down to refractoriness or a minimum coupling interval of 180 ms at two
drive cycle lengths (400 and 600 ms) did not induce VT. A substrate
approach was planned and LV mapping revealed a large low voltage
(< 1.5mV) inferior and lateral scar. PES from the septal
border zone of the scar with up to two extrastimuli following a basic
drive cycle length of 600 ms induced four different sustained
monomorphic VTs with cycle lengths of 268ms to 566ms and QRS
morphologies consistent with origin from the mid-lateral and
mid-inferoseptal aspects of the infarct scar. Following ablation, VTs
were no longer inducible with PES from either the RV or LV. NIPS two
days after the procedure via the RV lead of the patient’s defibrillator
did not induce VT.