Comparison of defibriliation efficacy in humans using a new catheter and superior vena cava spring-left ventricular patch electrodes

Abstract

The automatic implantable cardioverter-defibrillator currently utilizes an electrode system that requires a major operation for implantation. Effective defibrillaytion using an implantable cardioverter-defibrillator catheter positioned transvenously would eliminate the morbidity associated with such surgery. Fifteen patients undergoing defibrillator implantation were studied to compare the efficacy of the catheter with that of the superior vena cava spring (6.7 cm2, anode)-left ventricular patch (13.5 cm2, cathode) electrode system using truncated exponential waveforms with 60% tilt. The catheter is 11F in diameter and tripolar. A distal platinum-ridium tip used for pacing was separated by 4 mm from a middle 4.3 cm2platinum electrode; these were positioned at the right ventricular apex. The proximal 8.5 cm2platinum electrode was situated at the superior vena cava-right atrial junction.Defibriliation was performed using the middle (cathode) and proximal (anode) electrodes. Ventricular fibrillation was induced by alternating current six times, and defibnllation shocks of 1, 5, 10, 15, 20 or 25 J were given in random order, first using the catheter and then the springpatch system. Rescue shocks of higher energy were given if there was a failure. Although very low energy levels appeared to be slightly more efficacious when using the spring-patch system, there was no statistically significant difference between the electrode systems for any of the energies tested. Permanent implantation of the catheter would have been suitable in 45% of the patients, as compared with 54% of patient with the spring-patch system (p = NS). Therefore, a catheter system is feasible in some patients and, in the patient group studied, it compared favorably with the standard spring-patch configuration. Permanent catheter defibrillation deserves further study.