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Biphasic Defibrillation Using a Single Capacitor with Large Capacitance: Reduction of Peak Voltages and ICD Device Size
Author(s) -
BLOCK MICHAEL,
HAMMEL DIETER,
BöCKER DIRK,
BORGGREFE MARTIN,
BUDDE THOMAS,
ISBRUCH FRANK,
SCHELD HANS H.,
BREITHARDT GÜNTER
Publication year - 1996
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1996.tb03312.x
Subject(s) - defibrillation , waveform , defibrillation threshold , capacitor , medicine , voltage , capacitance , pulse generator , biomedical engineering , cardiology , electrical engineering , electrode , physics , quantum mechanics , engineering
The volume of current implantable cardioverter defibrillators (ICD) is not convenient for pectoral implantation. One way to reduce the size of the pulse generator is to find a more effective defibrillation pulse waveform generated from smaller volume capacitors. In a prospective randomized crossover study we compared the step‐down defibrillation threshold (DFT) of a standard biphasic waveform (STD), delivered by two 250‐μF capacitors connected in series with an 80% tilt, to an experimental biphasic waveform delivered by a single 450μF capacitor with a 60% tilt. The experimental waveform delivered the same energy with a lower peak voltage and a longer duration (LVLDj. Intraopera‐tively, in 25 patients receiving endocardial (n = 12) or endocardial‐subcutaneous array (n = 13) defibrillation leads, the DFT was determined for both waveforms. Energy requirements did not differ at DFT for the STD and LVLD waveforms with the low impedance (32 ± 4Ω) endocardial‐subcutaneous array defibrillation lead system (6.4 ± 4.4 J and 5.9 ± 4.2 J, respectively) or increased slightly (P ‐ 0.06) with the higher impedance (42 ± 4 Ω) endocardial lead system (10.4 ± 4.6 J and 12.7 ± 5.7 /. respectively), However, the voltage needed at DFT was one‐third lower with the LVLD waveform than with the STD waveform for both lead systems (256 ± 85 V vs 154 ± 53 V and 348 ± 76 V vs 232 ± 54 V, respectively). Thus, a single capacitor with a large capacitance can generate a defibrillation pulse with a substantial lower peak voltage requirement without significantly increasing the energy requirements. The volume reduction in using a single capacitor can decrease ICD device size.