Document Detail

Mechanisms of defibrillation. Critical points and the upper limit of vulnerability.
MedLine Citation:
PMID:  8656095     Owner:  NLM     Status:  MEDLINE    
The upper limit of vulnerability hypothesis for defibrillation states that a successful defibrillation shock must both stop the fibrillation wave fronts on the heart at the time that the shock is delivered and not start new wave fronts that will lead to reentrant circuits being formed, causing the heart to refibrillate. Mapping studies have demonstrated that defibrillation shocks can halt all wave fronts on the heart but fibrillation will begin again with an initial activation pattern that is different from the activation pattern on the heart just before the shock is delivered. In a fashion similar to the reinitiation of fibrillation following a failed defibrillation shock, properly sized and timed shocks can be delivered to the heart during paced rhythm to induce functional reentry that will initiate fibrillation. If the shocks are made incrementally larger, a shock level will be reached that is high enough not to start fibrillation in regular rhythm regardless of when it is delivered during the cardiac cycle. This shock level is called the upper limit of vulnerability. In this study, the formation of reentrant circuits with defibrillation-sized shocks and how this formation of reentrant circuits may be related to mechanism of defibrillation, via the upper limit of vulnerability hypothesis are discussed.
G P Walcott; K T Walcott; R E Ideker
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of electrocardiology     Volume:  28 Suppl     ISSN:  0022-0736     ISO Abbreviation:  J Electrocardiol     Publication Date:  1995  
Date Detail:
Created Date:  1996-07-26     Completed Date:  1996-07-26     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0153605     Medline TA:  J Electrocardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1-6     Citation Subset:  IM    
Department of Medicine, University of Alabama at Birmingham 35294-0019, USA.
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MeSH Terms
Action Potentials
Body Surface Potential Mapping
Cardiac Pacing, Artificial
Electric Countershock / methods*
Heart Conduction System / physiopathology
Heart Rate
Heart Ventricles / physiopathology
Models, Neurological
Refractory Period, Electrophysiological
Ventricular Fibrillation / physiopathology,  therapy*
Grant Support

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

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