The cellular electrophysiologic changes induced by ablation: comparison between argon laser photoablation and high-energy electrical ablation.

The cellular electrophysiologic effects of myocardial ablation performed in vitro with argon laser energy were compared with those of high-energy electrical shocks. A border zone of injured but nonnecrotic tissue surrounding the site of energy delivery was present after tissue ablation by both energy modalities. A decrease in resting membrane potential, action potential amplitude, and maximum rate of upstroke velocity was noted in each tissue sample, was greatest nearest the site of energy delivery, and was of graded severity at increasing distances from the crater edge. The extent of injury, as indexed by changes in action potential variables and necrosis, histologically determined, was greater for tissues exposed to high-energy shocks. The relatively focal injury after argon laser photoablation may explain the lower incidence of arrhythmias and hemodynamic dysfunction noted with the use of this method of ablation in vivo.