Document Detail

Effect of failed defibrillation shocks on electrogram amplitude in a nonintegrated transvenous defibrillation lead system.
MedLine Citation:
PMID:  7677081     Owner:  NLM     Status:  MEDLINE    
Concern has been raised regarding the ability of a nonthoracotomy integrated lead system to redetect ventricular fibrillation following failed defibrillation shocks due to diminution in postshock intracardiac electrogram amplitude. Whether such a problem could occur with other lead systems is not known, leading to uncertainty regarding a potential ongoing risk of sudden cardiac death in some patients despite implantable cardioverter-defibrillator therapy. To investigate this problem, we measured the amplitude of 10 consecutive ventricular fibrillation endocardial electrograms immediately before and immediately after failed defibrillation shocks in 15 patients at the time of implantation of a nonintegrated, transvenous, pace/sense/defibrillation lead. Overall, mean electrogram amplitude decreased 21%, from 10.7 +/- 4.6 mV before to 8.5 +/- 4.9 mV immediately after failed defibrillation shocks. The change in electrogram amplitude postshock was directly related to shock energy (r = 0.85, p < 0.0005), but shock waveform had no differential effect. Electrogram amplitude could also increase after failed shocks, particularly following those of low energy. No failures to redetect ventricular fibrillation were found. Thus, intracardiac electrogram amplitude is reduced following failed defibrillation shocks in this nonintegrated lead system, but by an amount less than that previously reported for some integrated lead systems. Our findings reveal that failed low energy defibrillation shocks are likely to result in less diminution in postshock intracardiac electrogram amplitude than high energy shocks, and that the postshock amplitude may even increase after some failed shocks.
P A Brady; P A Friedman; M S Stanton
Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  The American journal of cardiology     Volume:  76     ISSN:  0002-9149     ISO Abbreviation:  Am. J. Cardiol.     Publication Date:  1995 Sep 
Date Detail:
Created Date:  1995-10-18     Completed Date:  1995-10-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0207277     Medline TA:  Am J Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  580-4     Citation Subset:  AIM; IM    
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, USA.
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MeSH Terms
Defibrillators, Implantable* / statistics & numerical data
Electrocardiography / methods*,  statistics & numerical data
Electrodes, Implanted / statistics & numerical data
Equipment Design
Equipment Failure
Evaluation Studies as Topic
Middle Aged
Retrospective Studies
Treatment Failure
Ventricular Fibrillation / therapy

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

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