Document Detail

Evaluation of electrode polarity on defibrillation efficacy.
MedLine Citation:
PMID:  2916427     Owner:  NLM     Status:  MEDLINE    
The effect of electrode polarity on defibrillation thresholds in humans is unknown. This prospective, randomized evaluation of electrode polarity on defibrillation thresholds was performed in 21 survivors of ventricular fibrillation (VF) undergoing cardiac surgery. Defibrillation was always performed with 2 identical large rectangular, wire mesh electrodes positioned over the anterior wall of the right ventricle and the posterolateral wall of the left ventricle. The initial electrode polarity for the left ventricular (LV) electrode was chosen randomly for determination of the defibrillation threshold. Subsequently, electrode polarity was reversed. The defibrillation threshold was defined as the lowest pulse amplitude that would effectively terminate VF with a single discharge delivered 10 seconds after initiation of an episode of VF with alternating current. For each defibrillation pulse, voltage, current, resistance and delivered energy were recorded. Of the 21 patients, 15 (71%) had a lower defibrillation threshold when the LV electrode was positive, 2 patients (10%) had a lower defibrillation threshold when the LV electrode was negative and 4 patients (19%) had equal defibrillation thresholds (within 0.5 J) regardless of polarity. The mean leading edge defibrillation threshold voltage was 370 +/- 88 volts when the LV electrode was negative and 320 +/- 109 volts (14% less) when the LV electrode was positive (p = 0.014). Mean leading edge defibrillation threshold current was 9.3 +/- 3.1 amps when the LV electrode was negative compared to 7.7 +/- 3.1 amps (17% less) when the LV electrode was positive (p = 0.0033). There were no differences in resistance with the 2 configurations.(ABSTRACT TRUNCATED AT 250 WORDS)
G H Bardy; T D Ivey; M D Allen; G Johnson; H L Greene
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of cardiology     Volume:  63     ISSN:  0002-9149     ISO Abbreviation:  Am. J. Cardiol.     Publication Date:  1989 Feb 
Date Detail:
Created Date:  1989-03-17     Completed Date:  1989-03-17     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0207277     Medline TA:  Am J Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  433-7     Citation Subset:  AIM; IM    
Department of Medicine, University of Washington, Seattle.
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MeSH Terms
Electric Conductivity
Electric Countershock / instrumentation*
Middle Aged
Prospective Studies
Ventricular Fibrillation / therapy
Grant Support
R01-HL31472-01A3/HL/NHLBI NIH HHS; R23-HL36170-01/HL/NHLBI NIH HHS

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