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Short biphasic pulses from 90 microfarad capacitors lower defibrillation threshold.
MedLine Citation:
PMID:  8823832     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
For defibrillation between right ventricular and retropectoral patch electrodes using truncated exponential pulses, the stored energy defibrillation threshold (DFT) is lower for short pulses from small 60-microF capacitors than for conventional pulses from 120-microF capacitors, but 60-microF pulses frequently require higher voltages than are currently used. The goal of this study was to determine if DFT could be reduced by intermediate size 90-microF capacitors. This study compared biphasic waveform DFTs for 120 microF-65% tilt pulses, 90 microF-65% tilt pulses, and 90 microF-50% tilt pulses in 20 patients at defibrillator implantation. The 90 microF-50% tilt pulses were selected because their duration is half that of 120 microF-65% tilt pulses. The stored energy DFT for 90 microF-50% tilt pulses (9.1 +/- 4.3 J) was less than both the DFT for 120 microF-65% tilt pulses (12.0 +/- 5.5 J, P < 0.005) and the DFT for 90 microF-65% tilt pulses (11.6 +/- 5.8 J, P < 0.005). There was no significant difference between the latter two values. The voltage DFTs for 90 microF-50% pulses (436 +/- 113 V) and 120 microF-65% tilt pulses (436 +/- 104 V) were not statistically different; the voltage DFT for 90 microF-65% tilt pulses was higher than for either of the other two pulses (490 +/- 131, P < 0.005). The DFT was 20 J or greater in three patients for both 120 microF-65% tilt pulses and 90 microF-65% tilt pulses, but it was 16 J or less in all patients for 90 microF-50% tilt pulses. When pathways were dichotomized by the median resistance of 71 omega, 90 microF-50% tilt pulses significantly reduced DFTs compared to 120 microF-65% tilt pulses for higher resistance pathways (9.2 +/- 4.0 J vs 13.0 +/- 6.2 J, P = 0.002), but not lower resistance pathways (9.0 +/- 4.8 J vs 10.9 +/- 4.6 J, P = NS). For the electrode configuration tested, biphasic 90 microF-50% tilt pulses reduce stored energy DFT in comparison with 120 microF-65% tilt pulses without increasing voltage DFT. However, 90 microF-65% tilt pulses provide no benefit.
Authors:
C D Swerdlow; R M Kass; S Davie; P S Chen; C Hwang
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Pacing and clinical electrophysiology : PACE     Volume:  19     ISSN:  0147-8389     ISO Abbreviation:  Pacing Clin Electrophysiol     Publication Date:  1996 Jul 
Date Detail:
Created Date:  1996-12-10     Completed Date:  1996-12-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7803944     Medline TA:  Pacing Clin Electrophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1053-60     Citation Subset:  IM    
Affiliation:
Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California, USA.
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MeSH Terms
Descriptor/Qualifier:
Defibrillators, Implantable*
Electric Conductivity
Electric Countershock / instrumentation,  methods*
Electric Power Supplies
Female
Humans
Male
Middle Aged
Prospective Studies
Tachycardia, Ventricular / therapy*
Ventricular Fibrillation / therapy*

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


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