Intraoperative comparison of sequential-pulse and single-pulse defibrillation in candidates for automatic implantable defibrillators

Abstract

Sixteen survivors of cardiac arrest underwent intraoperative comparison of the effectiveness of sequential-pulse and single-pulse defibrillation. Defibrillation was tested alternately with the single-pulse or sequential-pulse technique 10 seconds into an episode of ventricular fibrillation that was induced with alternating current, the sequential-pulse defibrillation technique using truncated exponential pulses was performed with a right ventricular endocardial catheter and a left ventricular epicardial patch electrode. The first pulse was delivered between the right ventricular apical and the superior vena caval electrode on the right ventricular endocardial catheter. The second pulse was delivered between the right ventricular apical electrode and the left ventricular patch electrode 0.2 ms after termination of the first pulse. Single-pulse defibrillation was performed with a standard intracardiac defibrillation system in which a single truncated exponential pulse was delivered across 2 epicardial patch electrodes positioned over the anterolateral right ventricle and the posterolaterai left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and integrated to determine delivered energy. Average defibrillation threshold leading-edge voltage for the sequential pulse technique was 496 ± 140 V, compared with 365 ± 157 V for the single-pulse technique (p < 0.005). Defibrillation threshold leadingedge current for the sequential-pulse technique was 6.0 ± 2.3 A, compared with 10.6 ± 5.1 A for the single-pulse method (p < 0.0005). The defibrillation threshold delivered energy for the 2 methods was not significantly different: 13.0 ± 8.1 J for the sequential-pulse technique and 12.0 ± 8.9 J for the single pulse technique. In survivors of cardiac arrest, the single-pulse system delivers higher current and lower voltage, reflecting the lower impedance of the patch-patch lead system. Energy to terminate ventricular fibrillation successfully, however, was similar using either the sequential-pulse catheterpatch or single-pulse patch-patch method.