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Optimized First Phase Tilt in “Parallel‐Series” Biphasic Waveform
Author(s) -
YAMANOUCHI YOSHIO,
MOWREY KENT A.,
KROLL MARK W.,
BREWER JAMES E.,
DONOHOO ANN M.,
WILKOFF BRUCE L.,
TCHOU PATRICK J.
Publication year - 1997
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.1997.tb01828.x
Subject(s) - waveform , defibrillation , phase (matter) , series and parallel circuits , tilt (camera) , defibrillation threshold , pulse (music) , voltage , biomedical engineering , medicine , electrical engineering , physics , engineering , structural engineering , quantum mechanics
“Parallel‐Series” Biphasic Waveform. Introduction: A biphasic defibrillation waveform can achieve a large second phase leading‐edge voltage by a “parallel‐series” switching system. Recently, such a system using two 30‐μF capacitances demonstrated better defibrillation threshold than standard waveforms available in current implantable devices. However, the optimized tilt of such a “parallel‐series” system had not been defined. Methods and Results: Defibrillation thresholds were evaluated for five different biphasic “parallel‐series” waveforms (60/15 μF) and a biphasic “parallel‐parallel” waveform (60/60 μF) in 12 anesthetized pigs. The five “parallel‐series” waveforms had first phase tilts of 40%, 50%, 60%, 70%, and 80% with second phase pulse width of 3 msec. The “parallel‐parallel” waveform had first phase tilt of 50% with second phase pulse width of 3 msec. The defibrillation lead system comprised a left pectoral “hot can” electrode (cathode) and a right ventricular lead (anode). The stored energy at defibrillation threshold of the “parallel‐series” waveform with first phase tilts of 40%, 50%, 60%, 70%, and 80% was 7.0 ± 2.1, 6.1 ± 2.8, 6.8 ± 2.8, 7.2 ± 2.9. and 8.4 ± 3.1 J, respectively. The stored energy of the “parallel‐series” waveform with a 50% first phase tilt was 16% less than the nonswitching “parallel‐parallel” waveform (7.3 ± 2.8 J, P = 0.006). Conclusions: A first phase tilt of 50% maximized defibrillation efficacy of biphasic waveforms implemented with a “parallel‐series” switching system. This optimized “parallel‐series” waveform was more efficient than the comparable “parallel‐parallel” biphasic waveform having the same first phase capacitance and tilt.