Termination of reentry by a long-lasting AC shock in a slice of canine heart: a computational study.
J Cardiovasc Electrophysiol
; 13(12): 1253-61, 2002 Dec.
Article
en En
| MEDLINE
| ID: mdl-12521342
INTRODUCTION: A heart in fibrillation can be entrained by long-lasting alternating current (AC) stimuli, leading to defibrillation. To investigate the role entrainment plays in defibrillation, computer simulations of AC cardioversion in a three-dimensional slice of the canine heart were performed. METHODS AND RESULTS: A bidomain finite element model of a 1-mm thick slice across the ventricles of a canine heart was used to simulate termination of transmural reentry with AC shocks. Cardioversion defibrillation thresholds (DFTs) were determined for 200-msec (L) AC shocks at varying frequencies. At the DFT, the entire tissue is entrained by the AC shock. DFT decreases as the frequency of the long-lasting AC shock increases. We hypothesize that this decrease is due to the short period of the high-frequency AC waveform, leaving strong virtual electrode polarization (VEP) after the shock ends. To test this hypothesis, the end-shock VEP were compared for different frequencies, demonstrating stronger polarization as frequency increased. To examine whether entrainment by the long-lasting AC shock contributes to the VEP at the end of the shock, additional simulations were conducted using single-period (Z) AC waveforms. Z waveform DFTs were higher than L waveform DFTs; the Z waveform VEP was weaker than the L waveform VEP at the same frequency. This indicates that entrainment contributes to the development of stronger VEP and, thus, to lower DFT at high frequencies. CONCLUSION: This study offers for the first time a mechanistic insight into cardioversion with long-lasting AC shocks.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Cardioversión Eléctrica
/
Corazón
Límite:
Animals
Idioma:
En
Revista:
J Cardiovasc Electrophysiol
Asunto de la revista:
ANGIOLOGIA
/
CARDIOLOGIA
/
FISIOLOGIA
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos