Document Detail

Direct evidence of the role of virtual electrode-induced phase singularity in success and failure of defibrillation.
MedLine Citation:
PMID:  10969748     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: We recently demonstrated that virtual electrode-induced phase singularity is responsible for arrhythmogenesis during T wave shocks and explains the upper and lower limits of vulnerability. Furthermore, we suggested that the same mechanism might be responsible for defibrillation failure. The aim of this study was to experimentally support this hypothesis. METHODS AND RESULTS: We used the voltage-sensitive dye di-4-ANEPPS and fast imaging to assess electrical activity in Langendorff-perfused rabbit hearts. Ventricular arrhythmias were induced by monophasic shocks applied during T wave. Three types of defibrillation shocks (n = 79) were delivered from an intravenous right ventricular electrode: monophasic (8 msec), optimal biphasic (8/8 msec, 2/1 leading-edge voltage ratio), and nonoptimal biphasic (8/8 msec, 1/1 leading-edge voltage ratio). We found that a monophasic shock extinguished arrhythmic pattern of electrical activity via a virtual electrode polarization effect. However, the virtual electrode polarization was likely to produce phase singularities, leading to another arrhythmia and defibrillation failure. Nonoptimal biphasic shocks produced similar effects. Optimal biphasic shocks were successful because the first phase of the shock erased the arrhythmia via the virtual electrodes effect, whereas the second phase canceled the virtual electrodes, eliminating the substrate for phase singularities and arrhythmia resulting from them. CONCLUSION: Our data provide the first experimental support of the hypothesis implicating virtual electrode-induced phase singularity in defibrillation failure in the Langendorff-perfused rabbit heart. Optimal biphasic shock has a higher defibrillation efficacy because it does not produce virtual electrode-induced phase singularities.
I R Efimov; Y Cheng; Y Yamanouchi; P J Tchou
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of cardiovascular electrophysiology     Volume:  11     ISSN:  1045-3873     ISO Abbreviation:  J. Cardiovasc. Electrophysiol.     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2000-12-11     Completed Date:  2000-12-22     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9010756     Medline TA:  J Cardiovasc Electrophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  861-8     Citation Subset:  IM    
Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA.
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MeSH Terms
Arrhythmias, Cardiac / etiology,  physiopathology,  therapy
Electric Countershock / adverse effects,  instrumentation*,  standards*
Fluorescent Dyes
Heart / physiopathology
Pyridinium Compounds
Treatment Failure
Treatment Outcome
User-Computer Interface*
Grant Support
Reg. No./Substance:
0/Fluorescent Dyes; 0/Pyridinium Compounds; 90134-00-2/1-(3-sulfonatopropyl)-4-(beta)(2-(di-n-butylamino)-6-naphthylvinyl)pyridinium betaine

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