RF and microwave ablation for the treatment of ventricular tachycardia

Current RF ablation technology is limited by small lesion size. In order to enhance the size of RF-induced LV (left ventricular) endocardial lesions, the effects of an enlarged distal electrode tip and increased RF power on lesion volume were evaluated. Steerable electrode catheters with distal electrode tips of 4-12 mm were studied in anesthetized dogs at power settings of 20-100 W. Temperature was continuously monitored from a thermistor located at the tip of the catheter. RF energy (500 kHz, unmodulated) was applied between the tip of the catheter and a large skin electrode at four separate LV sites in each animal. Microwave ablation catheters with whip and helical antenna configurations were also tested. RF lesion volume increased with increasing delivered power and enlarged tip size. Average tip temperature correlated with measured lesion volume (r=0.66). Microwave catheters produced volume heating but the magnitude of heating was less than that observed for RF catheters. Catheter ablation of ventricular tachycardia may be enhanced by this technology.<>