Performance of a Novel Dual-Electrode Bipolar Radiofrequency Ablation Device: A Chronic Porcine Study

Objective: Over recent years, a variety of energy sources, including bipolar radiofrequency, have been used to replace the traditional incisions of the Cox-Maze procedure for the surgical treatment of atrial fibrillation (AF). The purpose of this study was to evaluate the safety and efficacy of a novel dual-electrode bipolar radiofrequency ablation device Synergy (Atricure, Inc., Cincinnati, OH USA) for AF in a chronic porcine model. Methods: Six domestic pigs underwent a modified Cox-Maze IV procedure without cardiopulmonary bypass using the Synergy device. Animals survived for 30 days. Each pig then underwent induction of AF and was killed to remove the heart en bloc for histologic assessment. Each ablation line was dissected perpendicularly at 5-mm intervals to assess the lesion width, depth, and transmurality. Results: All animals survived the operation. Electrical isolation of the left atrial appendage and the pulmonary veins were documented by pacing acutely and at 30 days after the operation in all six animals. All animals failed to be induced in AF at 30 days. There was no gross evidence of intra-atrial thrombus formation or stricture of the pulmonary veins. All ablations (n = 209) examined were discrete, linear, and transmural, with a mean lesion width of 3.0 ± 0.7 mm and a mean lesion depth of 5.4 ± 3.3 mm. The mean ablation time was 16.3 ± 4.4 seconds, with a mean total energy delivery of 238 ± 170 J. Conclusions: The Atricure Synergy was able to create reliable chronic transmural lesions of the modified Cox-Maze IV procedure on a porcine beating heart without cardiopulmonary bypass. The ablation lines were significantly wider when compared with its predecessor, the Isolator II.