Document Detail

Epicardial activation after unsuccessful defibrillation shocks in dogs.
MedLine Citation:
PMID:  3177679     Owner:  NLM     Status:  MEDLINE    
To study defibrillation, shocks were given to seven dogs during electrically induced fibrillation, while recordings were made from 56 epicardial electrodes. Shocks were given via electrodes on the left ventricular apex and the right atrium, creating an uneven shock field with much higher potential gradients in the apex than in the base of the ventricles. For unsuccessful 0.01- to 0.05-J shocks, activation occurred soon after the shock at many sites in both the base and the apex. For 0.1- to 0.5-J shocks, the number of early activation sites was greatly decreased, and the latency from the shock until earliest recorded activation was greatly increased at the apex but not at the base. For 1- to 5-J shocks, one to three early sites were present and confined to the base, with a long latency between the shock and the appearance of these early sites. The latency and location of earliest activation were similar to those after 1- to 5-J shocks given to induce fibrillation during normal paced rhythm. Shocks of 10 J successfully defibrillated. These findings suggest that the shock field can have at least three effects. One, a weak field fails to halt the activation fronts of fibrillation. Two, a stronger field halts but then reinduces fibrillation in a manner similar to that of the same strength field during the vulnerable period of normal rhythm. Three, a still higher field halts fibrillation without reinitiating it. Successful defibrillation requires a shock strong enough to create this third field intensity throughout the ventricles.
N Shibata; P S Chen; E G Dixon; P D Wolf; N D Danieley; W M Smith; R E Ideker
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  255     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1988 Oct 
Date Detail:
Created Date:  1988-11-09     Completed Date:  1988-11-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H902-9     Citation Subset:  IM    
Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
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MeSH Terms
Electric Countershock*
Models, Cardiovascular
Pericardium / physiopathology*
Ventricular Fibrillation / physiopathology*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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