| Increasing fibrillation duration enhances relative asymmetrical biphasic versus monophasic defibrillator waveform efficacy. | |
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MedLine Citation:
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PMID: 2376078 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Biphasic waveforms reduce defibrillation threshold compared with corresponding monophasic waveforms. However, effects of fibrillation duration on relative efficacy of monophasic and biphasic waveforms are unknown. This study used a newly developed defibrillation model, the isolated right- and left-sided working rabbit heart, with epicardial defibrillation electrodes, to compare threshold for a monophasic waveform (5 msec rectangular) and an asymmetrical biphasic waveform (5 msec each pulse, V2 = 50% V1). Mean voltage defibrillation threshold (V50) was determined from sigmoidal probability of successful defibrillation versus shock intensity curves after 5, 15, and 30 seconds of fibrillation in a paired study with 10 hearts. Results showed that biphasic waveforms had significantly lower voltage and energy thresholds at all fibrillation durations and that their relative efficacy improved with increasing fibrillation duration. Biphasic voltage threshold was 38.2 +/- 2.2, 44.7 +/- 4.8, and 46.6 +/- 3.2 V after 5, 15, and 30 seconds of fibrillation compared with monophasic thresholds of 51.7 +/- 4.4 (p less than 0.002), 63.0 +/- 7.6 (p less than 0.05), and 72.1 +/- 3.9 V (p less than 0.005). Biphasic waveform energy threshold was 0.67 that for the monophasic waveform after 5 seconds of fibrillation (0.12 +/- 0.01 versus 0.18 +/- 0.03 J, p less than 0.05). The ratio between biphasic waveform threshold and monophasic waveform threshold (B/M) decreased to 0.62 at 15 seconds. At 30 seconds, B/M was 0.52 (0.17 +/- 0.02 versus 0.33 +/- 0.04 J, p less than 0.02). This study also showed that biphasic waveform threshold was a nonlinear function of monophasic waveform threshold so that improved biphasic defibrillator waveform efficacy was greatest for hearts having higher monophasic thresholds.(ABSTRACT TRUNCATED AT 250 WORDS) |
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Authors:
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J L Jones; J F Swartz; R E Jones; R Fletcher |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Circulation research Volume: 67 ISSN: 0009-7330 ISO Abbreviation: Circ. Res. Publication Date: 1990 Aug |
Date Detail:
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Created Date: 1990-09-06 Completed Date: 1990-09-06 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0047103 Medline TA: Circ Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 376-84 Citation Subset: IM |
Affiliation:
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Department of Physiology and Biophysics, Georgetown University, Washington, DC 20037. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Electric Countershock* Electric Stimulation Heart / physiopathology* Heart Ventricles / physiopathology Perfusion Probability Rabbits Time Factors Ventricular Fibrillation / physiopathology* |
| Grant Support | |
ID/Acronym/Agency:
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HL-24606/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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