Large change in voltage at phase reversal improves biphasic defibrillation thresholds. Parallel-series mode switching.
Circulation
; 94(7): 1768-73, 1996 Oct 01.
Article
em En
| MEDLINE
| ID: mdl-8840873
ABSTRACT
BACKGROUND:
Multiple factors contribute to an improved defibrillation threshold of biphasic shocks. The leading-edge voltage of the second phase may be an important factor in reducing the defibrillation threshold. METHODS ANDRESULTS:
We tested two experimental biphasic waveforms with large voltage changes at phase reversal. The phase 2 leading-edge voltage was twice the phase 1 trailing-edge voltage. This large voltage change was achieved by switching two capacitors from parallel to series mode at phase reversal. Two capacitors were tested (60/15 microfarads [microF] and 90/22.5 microF) and compared with two control biphasic waveforms for which the phase 1 trailing-edge voltage equaled the phase 2 leading-edge voltage. The control waveforms were incorporated into clinical (135/135 microF) or investigational devices (90/90 microF). Defibrillation threshold parameters were evaluated in eight anesthetized pigs by use of a nonthoracotomy transvenous lead to a can electrode system. The stored energy at the defibrillation threshold (ion joules) was 8.2 +/- 1.5 for 60/15 microF (P < .01 versus 135/135 microF and 90/90 microF), 8.8 +/- 2.4 for 90/22.5 microF (P < .01 versus 135/135 microF and 90/90 microF), 12.5 +/- 3.4 for 135/135 microF, and 12.6 +/- 2.6 for 90/90 microF.CONCLUSIONS:
The biphasic waveform with large voltage changes at phase reversal caused by parallel-series mode switching appeared to improve the ventricular defibrillation threshold in a pig model compared with a currently available biphasic waveform. The 60/15-microF capacitor performed as well as the 90/ 22.5-microF capacitor in the experimental waveform. Thus, smaller capacitors may allow reduction in device size without sacrificing defibrillation threshold energy requirements.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cardioversão Elétrica
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Circulation
Ano de publicação:
1996
Tipo de documento:
Article