Temperature-controlled high frequency ablation for creation of transmyocardial channels: In vivo validation of a novel method

Objective: We investigated the feasibility and short-term effects of a nove l procedure to create intramyocardial channels by means of high frequency ( HF) ablation in a rabbit in vivo model. Methods: A flexible catheter ending in a cylindrical electrode (diameter 0.7 mm) with a sharpened tip was used for HF energy application following transmyocardial insertion. Power-contr olled or energy-controlled energy applications were performed in 16 anesthe tized rabbits after thoracotomy with a follow-up for 3 h. Assessment of myo cardial channels and the necrotic zone was performed by morphometric quanti fication in serial sections. The ferret diameter was used to compare channe l dimensions and the extent of necrosis. Results: Thirty-nine power-control led and 54 temperature-controlled HF applications were performed. The shape of identified channels was round in 71% and 69% had a lumen patency of gre ater than or similar to 213 of the channel. Ferret diameter of the channels was 414 +/- 180 mu m and of the necrotic zone 3,558 +/- 1,200 mu m. In tem perature-controlled applications, channel dimensions were strongly influenc ed by the maximum tissue temperature and the duration of energy delivery (T -max: p = 0.0006; duration: p = 0.003). Channel and necrosis dimensions cor related better with biometric parameters in temperature-controlled compared with power-controlled applications. Conclusion: Mechanically created trans myocardial channels can be stabilized by HF heating of the surrounding tiss ue. A high percentage of these channels remain patent. The channel dimensio ns are closely correlated with maximum temperature and duration of energy d elivery in a temperature-controlled application mode. Copyright (C) 2000 S. Karger AG, Basel.