ADDITIONAL LEAD IMPROVES DEFIBRILLATION EFFICACY WITH AN ABDOMINAL HOT CAN ELECTRODE SYSTEM

Background Although the left prepectoral site is preferred for ''hot c an'' placement, this site is unavailable in some patients. We evaluate d the influence of electrode location on defibrillation thresholds wit h alternative hot can and transvenous lead configurations. Methods and Results Three interrelated studies were performed. In group 1, the im portance of hot can location was investigated by pairing a right ventr icular lead to five different hot can placement sites in seven pigs. T he defibrillation energies for right pectoral, left pectoral, left sub axillary, and right and left abdominal hot can sites were 20.3+/-2.7, 15.9+/-3.8, 14.9+/-2.5, 32.0+/-3.4, and 30.0+/-3.4 J,* respectively (P<.005 versus left pectoral and left subaxillary sites). In group 2, the value of a three-electrode configuration with an abdominal hot ca n placement was investigated by adding a subclavian vein lead to the p ectoral or abdominal hot can configurations in seven pigs. The defibri llation energies for-left pectoral and abdominal sites were 18.6+/-4.2 and 29.0+/-5.8 J (P=.0001), respectively. The addition of a right or let subclavian vein lead with an abdominal hot can reduced the thresho ld to 19.3+/-4.2 or 18.8+/-3.2,* respectively (*P=.0001 versus abdomi nal site). In group 3, the contribution of the abdominal hot can elect rode to the three-electrode configuration was tested by a comparison w ith two purely transvenous two-electrode configurations in six pigs. T he defibrillation energy (19.9+/-3.2 J) for the abdominal hot can with a subclavian vein lead was lower than the transvenous lead configurat ions with a subclavian vein (29.0+/-2.5 J, P=.0001) or a superior vena cava lead (30.7+/-3.7 J, P=.0001). The right ventricular lead was the sole cathode during the first phase of the biphasic shock in all expe riments. Conclusions Defibrillation energy depends on the hot can plac ement site. The addition of a subclavian vein lead with an abdominal h ot can improves defibrillation efficacy to the level of the pectoral p lacement and is better than a purely transvenous lead configuration.