714-5 ICD Device Size can be Reduced by Smaller Capacitors

Abstract

ICDs with smaller capacitors (C) and less maximum energy (E) output than today's ICDs might allow implantation of endocardiallead systems with an acceptable safety margin in some patients. Using small capacitors that deliver shorter duration (SD) waveforms would significantly reduce ICD size. Intraoperatively, standard (STD) and SD biphasic (60:40, 80% tilt) waveforms were compared using a cross-over study design: Waveform Defibrillator C [μF] E[J] STD VENTAK® ECD 2815 125 38(780 V) SD VENTAK® ECD RSD2815 90 20-23 (660 V) In 30 patients (age: 59 ± 10; male: 24, CAD: 22, DCM: 4, EF 42 ± 15%, amiodarone: 8), the defibrillation threshold (DFT) was determined using a step-down protocol (20, 15, 10,8, 5, 3, 2, 1 J) during ICD implantation. Patients were randomized to receive an endocardial defibrillation lead-alone (TV; Endotak ® 0072, n = 15) or in combination with a subcutaneous defibrillation array (SC, Endotak ® 0048, n = 15). The SD waveform defibrillated with energies ≤ 10 J in 67% of the patients with TV and 80% of the patients with SC. DFT All [J] TV[J] SC[J] All [V] TV [V] SC[V] STD 9.5 ± 4.9 11.3 ± 4.4 7.7 ± 3.9 322 ± 80 360 ± 74 284 ± 68 SD 10.3 ± 4.1 11.2 ± 46 9.4 ± 3.3 411 ± 80 431 ± 92 392 ± 65 P n.s. n.s. n.s. <0.0001 0.0012 0.0002 The significantly higher voltages of the SD waveform did not significantly reduce the the sensing electrogram amplitude 6 s after a 15 J shock compared to the STD waveform (0.92 ± 0.22 vs. 0.91 ± 0.17). A shorter duration waveform delivered by smaller capacitors with less maximum energy output yielded a 10 J safety margin for endocardial lead-alone defibrillation in approx. 67% (resp. 80% combined with SC) of the patients tested. Despite higher voltages for the same energy output reductions in post-shock electrogram amplitude were not larger than those seen with standard capacitors.