Use of multiple patches during implantation of epicardial defibrillator systems

During implantation of epicardial automatic defibrillator systems, occasional patients have difficulty in obtaining adequate defibrillation thresholds. Of 236 consecutive patients undergoing implantation of epicardial defibrillator systems, 18 patients received a 3-patch (n = 15) or 4-patch (n = 3) defibrillator system. Twelve patients who received & multiple patch defibrillator system had a best 2-patch defibrillation energy requirement of ≥30 J; in the remaining 6 patients less stringent clinical criteria were used in the decision to add a third defibrillator patch (defibrillation energy requirement >18 J in 4 patients, and >20 J in 2 patients). Technically, multiple-patch systems were made possible with either the use of Y-connectors or defibrillators allowing output to 3 patches. In 3 patients, addition of a third epicardial patch still resulted in a defibrillation energy requirement of ≥30 J; in these 3 patients, addition of a fourth patch resulted in a defibrillation energy requirement of ≤20 J. All patients receiving a multiplepatch defibrillator system had a reduction in defibrillation energy requirement, and 12 patients had a reduction in defibrillation energy requirement of ≥10 J over the best 2-patch defibrillation energy requirement in the patients who eventually had placement of a multiple-patch system, the best 2-patch defibrillation energy requirement was >18 J in 4 patients, >20 J in 2 patients, ≥30 J in 9 patients, and >40 J in 3 patients. After placement of a multiple-patch system, the defibrillation energy requirement was ≤24 J in 1 patient, ≤20 J in 5 patients, ≤18 J in 8 patients, ≤15 J in 2 patients, and ≤10 J in 2 patients. This improvement was significant (p < 0.005). During implantable defibrillator placement associated with a high defibrillation energy requirement with a 2-patch system, placement of a 3- or 4-patch system may result in a marked improvement in defibrillation energy requirement.