Comparison of pulsed versus continuous radiofrequency energy delivery: Diameter of lesions induced with multipolar ablation catheter

The aim of this study was to compare the efficacy of pulsed versus continuo us RF energy delivery via multipolar ablation catheters. In vitro tests wer e performed in endomyocardial preparations of fresh bovine hearts in a bath of physiological saline solution (37 degreesC) at constant flow conditions (1.5 L/min). The catheters were applied to the endocardium at a constant p ressure. Energy wets delivered pulsed (to 4 electrodes simultaneously, 5-ms duty cycle) or continuously (to each electrode separately). in vivo experi ments were performed under fluoroscopy in eight anesthetized pigs, guided b y endocardial electrograms to place the catheters in 22 different intraatri al positions. Lesion volume was calculated from measurements of the lesion diameter with a microcaliper. The homogeneity of the lesions was classified from 1 (highest) to 4 (least). More homogeneous linear lesions were produc ed in significantly less time with pulsed than with continuous energy deliv ery. There were no differences in electrode temperature or impedance values in vitro and in vivo. The results in the in vitro experiments were reprodu cible in the intact animal experiments. Significantly larger and more homog eneous linear lesions were created more rapidly with pulsed than with conti nuous energy delivery.