Document Detail


Effect of acute global ischemia on the upper limit of vulnerability: a simulation study.
MedLine Citation:
PMID:  14751853     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The goal of this modeling research is to provide mechanistic insight into the effect of altered membrane kinetics associated with 5-12 min of acute global ischemia on the upper limit of cardiac vulnerability (ULV) to electric shocks. We simulate electrical activity in a finite-element bidomain model of a 4-mm-thick slice through the canine ventricles that incorporates realistic geometry and fiber architecture. Global acute ischemia is represented by changes in membrane dynamics due to hyperkalemia, acidosis, and hypoxia. Two stages of acute ischemia are simulated corresponding to 5-7 min (stage 1) and 10-12 min (stage 2) after the onset of ischemia. Monophasic shocks are delivered in normoxia and ischemia over a range of coupling intervals, and their outcomes are examined to determine the highest shock strength that resulted in induction of reentrant arrhythmia. Our results demonstrate that acute ischemia stage 1 results in ULV reduction to 0.8A from its normoxic value of 1.4A. In contrast, no arrhythmia is induced regardless of shock strength in acute ischemia stage 2. An investigation of mechanisms underlying this behavior revealed that decreased postshock refractoriness resulting mainly from 1) ischemic electrophysiological substrate and 2) decrease in the extent of areas positively-polarized by the shock is responsible for the change in ULV during stage 1. In contrast, conduction failure is the main cause for the lack of vulnerability in acute ischemia stage 2. The insight provided by this study furthers our understanding of mechanisms by which acute ischemia-induced changes at the ionic level modulate cardiac vulnerability to electric shocks.
Authors:
Blanca Rodríguez; Brock M Tice; James C Eason; Felipe Aguel; José M Ferrero; Natalia Trayanova
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2004-01-29
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  286     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2004 Jun 
Date Detail:
Created Date:  2004-05-18     Completed Date:  2004-06-28     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H2078-88     Citation Subset:  IM    
Affiliation:
Dept. of Biomedical Engineering, Tulane University, New Orleans, LA 70118, USA. blanca@tulane.edu
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MeSH Terms
Descriptor/Qualifier:
Action Potentials / physiology
Acute Disease
Animals
Arrhythmias, Cardiac / physiopathology,  therapy*
Computer Simulation*
Dogs
Electric Countershock*
Heart Conduction System / physiopathology
Models, Cardiovascular*
Myocardial Ischemia / physiopathology*
Oxygen / physiology
Grant Support
ID/Acronym/Agency:
HL 063196/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
7782-44-7/Oxygen

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


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