CATHETER ABLATION OF CANINE VENTRICULAR MYOCARDIUM - THE USE OF REPETITIVE SHORT-TIME CONSTANT CAPACITIVE SHOCKS TO INCREASE LESION VOLUME

Arching and barotrauma, seen with high energy DC catheter ablation, ar e responsible for diffuse cardiac damage and coronary sinus rupture. I n six anesthetized dogs, we investigated the effects of an increasing number of short time-constant capacitive shocks on the volume of myoca rdial damage. Each dog received capacitive shocks of 2 J/kg at 3 sites in the left ventricle. One shock was delivered in 2 dogs, 2 shocks we re delivered in 2 dogs and 3 shocks were delivered in 2 dogs. Shock de livery was not accompanied by hemodynamic collapse, sustained ventricu lar tachycardia or ventricular fibrillation. The dogs were sacrificed at 60 minutes. Mean (SEM) lesion volumes were 195 (39) mm(3), 480 (41) mm(3), and 595 (110)mm(3), respectively. Despite variability in indiv idual volume of damage, there was a significant increase in lesion vol ume with an increasing number of shocks. There was no evidence of perf oration or tamponade. Increasing myocardial damage can be produced usi ng repetitive capacitive shocks. Delivery of 2 shocks produces clinica lly useful lesions without the adverse effects associated with single high energy shocks. Repetitive capacitive shocks offer a method of inc reasing lesion volume without increasing energy and thereby without co mpromising safety.