Document Detail

Defibrillation causes immediate cardiac dilation in humans.
MedLine Citation:
PMID:  12890045     Owner:  NLM     Status:  MEDLINE    
Defibrillation Causes Dilation. INTRODUCTION: Prior studies in isolated heart tissue have shown both excitation and deexcitation to be the primary mechanism of defibrillation. This article presents the first evidence in man of deexcitation immediately following defibrillation by tracking the heart's mechanical response. METHODS AND RESULTS: The geometric changes of the ventricular chambers were measured before and after defibrillation in seven human subjects receiving an implantable cardioverter defibrillator (ICD). The ICD was used to produce approximately three episodes of ventricular fibrillation and defibrillation in each subject. Twenty-two two-dimensional echocardiographic images of the right ventricle (RV) and 11 images of the left ventricle (LV) were recorded and analyzed at 30 frames per second. Just over 2 seconds of each episode were digitized, beginning half a second before the defibrillation shock. Individual frames were analyzed to yield cross-sectional, ventricular chamber area as a function of time. Immediately following defibrillation, ventricular chambers dilated with significant fractional area increase (RV: 1.58 +/- 0.25, LV: 1.10 +/- 0.06), with peak dilation at 194 +/- 114 msec. CONCLUSION: Defibrillation causes a rapid increase in ventricular chamber area due to relaxation of the myocardium, suggesting that defibrillation synchronizes the cardiac cells to the deexcited state in man.
Erin Sylvester; Eric Johnson; Paul Hess; Robert Malkin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cardiovascular electrophysiology     Volume:  14     ISSN:  1045-3873     ISO Abbreviation:  J. Cardiovasc. Electrophysiol.     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-07-31     Completed Date:  2004-01-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9010756     Medline TA:  J Cardiovasc Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  832-6     Citation Subset:  IM    
The University of Memphis, Memphis, Tennessee 38152, USA.
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MeSH Terms
Cardiomyopathy, Dilated / physiopathology,  ultrasonography
Defibrillators, Implantable*
Electric Countershock / methods*
Heart Diseases / diagnosis,  physiopathology,  therapy*,  ultrasonography*
Myocardial Contraction*
Stroke Volume
Ventricular Dysfunction, Left / physiopathology,  ultrasonography*
Ventricular Dysfunction, Right / physiopathology,  ultrasonography*

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