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- Title
Effect of Changing Capacitors Between Phases of a Biphasic Defibrillation Shock.
- Authors
Walcott, Gregory P.; Rollins, Dennis L.; Smith, William M.; Ideker, Raymond E.
- Abstract
Background: In this study, we examined the effect of changing capacitor values between phases of a biphasic waveform with the goal of lowering leading edge voltage (LEV), total delivered energy (TDE), and total stored energy (TSE). Methods: Defibrillation thresholds were determined in 18 open-chest swine using epicardial patch electrodes. In part I, three combinations of capacitors were tested: 150:150 μF; 150:300 μF; and 300:150 μF, Waveform durations were 6/0, 6/2, 6/4, 6/6, and 6/8 ms. In part II. phase 1 capacitance was 150 μF;. Three phase 2 capacitance values were used: 150 μF; 75 μF; and 37.5 μF. Phase 2 LEV was a multiple of phase 1 trailing edge voltage: X 0,5: X 0,75: X 3; X 2,- X 3: and X 4. A 3.5/2.0 ms biphasic waveform was used. In part III, thresholds were determined for two sets of capacitor values, which can be created by switching a pair of capacitors from in parallel to in series, 150:37.5 μF and 300:75 IxF. and nine waveform durations. 4/0, 4/2, 4/4, 6/0. 6/3, 6/6. 8/0, 8/4, and 8/8 ms. Results: In part I, the 300:150 μF system defibrillated with the lowest LEV. TDE and TSE were not different for any of the biphasic waveforms tested except for the 6/8 ms, which was higher. In part II, there was no difference in LEV among any of the three phase 2 capacitor values. LEV was lowest for the X 2, X 3, x 4 multipliers. Peak voltage was lowest for the X 1 and x 2 multipliers. TDE was lowest for the X 0.5, X 0.75, X 1, and X 2 multipliers. In part III, the 300:75 μFsystem defibrillated at a lower LEV than did the 150:37.5 μF system. The 150:37.5 μF system defibrillated at a lower total delivered energy than did the 300:75 μF. Conclusion: These results suggest that defibrillation can be accomplished with lower LEV. TDE. and TSE if two capacitors are switched from a parallel configuration to a series configuration between phases of the biphasic waveform.
- Subjects
DEFIBRILLATORS; ELECTRIC countershock; CAPACITORS; ELECTRONICS in cardiology; ELECTRODES
- Publication
Pacing & Clinical Electrophysiology, 1996, Vol 19, Issue 6, p945
- ISSN
0147-8389
- Publication type
Article
- DOI
10.1111/j.1540-8159.1996.tb03391.x