SIMULTANEOUS MULTIPOLAR RADIOFREQUENCY ABLATION IN THE MONOPOLAR MODEINCREASES LESION SIZE

Delivery of radiofrequency (RF) energy from the distal tip of electrop hysiology catheters produces lesions that may be too small to ablate a rrhythmogenic sites during a single application of RF energy. To produ ce larger lesions, we delivered RF energy via a quadripolar catheter i n which all four electrodes were connected in unipolar fashion. The ca theter (Webster Labs) had a 4-mm tip, 2-mm ring electrodes, and 2-mm i nterelectrode distance. Lesion size was compared using RF energy deliv ered in a multipolar configuration with that delivered only to the dis tal tip using fresh bovine ventricular tissue. in vivo, RF lesions wer e made in dogs using the distal tip as well as all four poles of the s ame catheter inserted percutaneously. RF energy was delivered using a constant voltage at a frequency of 400 kHz. Preliminary experiments we re conducted to determine the maximum power deliverable without coagul ation using each electrode configuration. The use of simultaneous mult ipolar RF ablation produced significantly larger lesions both in vitro and in vivo. The length of the lesion was increased by a factor of ap proximately 2 in both the in vitro and in vivo experiments. There was a trend toward an increasing depth of the lesion by simultaneously app lying RF energy to all four electrodes. Lesion width was significantly increased in the in vivo studies. We concluded that simultaneous mult ipolar delivery of RF energy produces larger lesions than can be obtai ned with delivery of RF energy to the distal tip alone. This technique may offer a means of increasing lesion size, leading to a decrease in the number of applications of RF energy necessary for ablation of arr hythmias.