Optimal method to achieve consistently low defibrillation energy requirements

Reduction of the defibrillation energy requirement offers the opportunity t o decrease implantable cardioverter defibrillator (ICD) size and to increas e device longevity. Therefore, the purpose of this prospective study was to obtain confirmed defibrillation thresholds (DFTs) of less than or equal to 15 J in each patient with an endocardial dual-coil lead system incorporati ng an active pectoral pulse generator (TRIAD lead system: RV- --> SVC+ + CA N(+)). According to our previous clinical and experimental studies, we trie d to lower DFTs that were >15 J by repositioning the distal coil of the end ocardial lead system in the right ventricle. A total of 190 consecutive pat ients requiring ICDs for ventricular fibrillation and/or recurrent ventricu lar tachycardia were investigated at the time of ICD implantation (42 women , 148 men; mean age 61.9 +/- 12.0 years; mean left ventricular ejection fra ction 42.7 +/- 16.6%). Coronary artery disease was present in 139 patients; nonischemic dilated cardiomyopathy in 34 patients; and other etiologies in 17 patients; 47 patients had undergone previous cardiac surgery. Regardles s of optimal pacing and sensing parameters, for patients having DFTs >15, w e repositioned the distal coil of the endocardial lead system toward the in traventricular septum to include this part of both ventricles within the el ectrical defibrillating field. In 177 of 190 patients, induced ventricular fibrillation was successfully terminated with less than or equal to 15 J (g roup I) using the initial lead position. Repositioning of the endocardial l ead was necessary in 13 patients whose DFTplus (DFTplus = second additional success at lowest energy level) were >15 J (group II). In all patients, re positioning was successful within a 15 J energy level (100% success). The m ean DFTplus was 7.3 +/- 3.5 J (group I) and 11.0 +/- 4.5 J (group II; p < 0 .005). The mean DFTplus of all patients enrolled in the study was 7.6 +/- 3 .7 J (range: 2 to 15 J). In 87% of all patients, DFTplus of <less than or e qual to>10 J was achieved. Repositioning of the endocardial lead in the rig ht ventricle is a simple and effective method to reduce intraoperative high DFTs. As a result of this procedure, ICDs with a 20 J output should be suf ficient for the vast majority (87%) of our patients. Furthermore, we were a ble to avoid additional subcutaneous or epicardial electrodes in all patien ts. (C) 2000 by Excerpta Medica, Inc.