THE ROLE OF ELECTROLYTE IN LESION SIZE USING AN IRRIGATED RADIOFREQUENCY ELECTRODE

Multiple attempts have been made to eliminate atrial fibrillation by p erforming the surgical maze procedure with radiofrequency energy. Curr ently, this is limited because of the risk of atrial perforation and t he lack of transmural penetration. Saline irrigation has been investig ated as a method of radiofrequency cautery tip cooling to prevent rapi d temperature and impedance rises, which have been shown to lead to pe rforation or decreased radiofrequency penetration after eschar formati on. There are few data on the influence that different types of electr olyte irrigation solutions have on lesion depth. Using a novel hollow cautery pen, we infused either an electrolyte solution (0.9%, 3%, 14.6 %, or 23.4% sodium chloride), a nonelectrolyte solution (1.5% glycine) , or no irrigation to produce 819 lesions on 14 left ventricles in swi ne using radiofrequency energy (450 +/- 10 kHz) applied at two output settings (20 and 75 watts). The nonelectrolyte solution increased lesi on depth compared with no infusion at 20 watts but produced shallower lesion depths compared with electrolyte solutions at 75 watts. Compare d with the other electrolyte solutions, the 0.9% sodium chloride solut ion produced the deepest lesions (3.34 +/- 0.06 mm) at 75 watts (p < 0 .001). As the concentration of electrolyte increased, lesion depth dec reased unless generator output increased. Formation of eschar and tiss ue destruction was seen in the noninfusion and nonelectrolyte groups b ut not in the electrolyte group. A conductive media coupled with radio frequency energy allowed for greater lesion depth than irrigated cooli ng with a nonelectrolyte solution or no irrigation. There was an inver se relationship between electrolyte concentration and lesion depth. We conclude that the concentration of electrolyte irrigant is an importa nt consideration when choosing a solution to improve transmural penetr ation and decrease the risk of tissue destruction from radiofrequency energy.