Comparison between pulsed and continuous radiofrequency delivery

Potentials arising in the pulmonary veins (PV) have been proposed to be a trigger of atrial fibrillation. Percutaneously, the best results for curative treatment of atrial fibrillation have been achieved by segmental or circumferential isolation of the PV. The purpose of our study was to determine the feasibility of ostial pulmonary vein isolation and to compare continuous radiofrequency (RF) with pulsed RF concerning homogeneity and transmurality of produced lesions. In vivo tests were performed in seven anesthetized and ventilated pigs. Under fluoroscopy and guided by intracardiac electrograms each of the 28 pulmonary veins was targeted for circumferential isolation near its ostium. After the continuous energy application in one PV-ostium the catheter was placed into the next PV-ostium and the same procedure was repeated using pulsed energy. The ablations were performed with an octapolar circumferential ablation catheter, with either continuous RF energy delivery to each electrode for 120 s or pulsed energy delivery to four electrodes simultaneously with a 5 ms duty cycle. Lesion diameter was measured with a microcaliper and homogeneity classified from 1 (highest) to 4 (least). More homogeneous lesions were produced in significantly less time with pulsed rather than with continuous energy delivery. There were no significant differences in impedance or temperature of the electrodes. We did not observe tissue carbonization or "popping," pulmonary vein stenosis, pericardial effusion/perforation at any time. Ostial ablation of the PV with pulsed energy delivery proved feasible. It was the faster and more reliable method of creating linear circumferential lesions with a maximum amount of homogeneity and transmurality. We observed no elevated risk of PV stenosis during our experiments.