TY - GEN
T1 - Temporal variability of defibrillation threshold in a two-dimensional supercomputer model of 'ventricular fibrillation'
AU - Fishier, Matthew G.
AU - Thakor, Nitish V.
N1 - Publisher Copyright:
© 1992 IEEE.
PY - 1992
Y1 - 1992
N2 - We have investigated the question: Do defibrillation thresholds (DFTs) vary during an episode of 'fibrillation,' and if so, what are the cellular mechanisms involved? Unstable microreentry ('fibrillation') and defibrillation (DF) shocks were simulated in a two-dimensional model of cardiac tissue on a massively parallel processor Connection Machine. The modelled tissue consisted of 16384 (128×128) 100 × 100 μm2 ventricular patches that obeyed modified Beeler-Reuter membrane kinetics. Reentry was initiated by stimulating the central region of the sheet during the repolarization phase of a passing planar wavefront. The DFT was then determined for several times following this premature stimulus. DFTs remained low (< 13 μA/cm2) until the initial figure-of-eight reentry degenerated into multiple unstable vortices (DFT ≈ 21 μA/cm2). Superimposed on this jump in DFTs was a small (±2.5 μA/cm2) quasi-periodic oscillation in DFTs whose average frequency correlated with the rotational frequency of the vortices. Therefore, we conclude that (1) there exists temporal variation in DFTs during fibrillation, (2) DFTs are lower during early fibrillation, and (3) DF shocks above ≈ 24 μA/cm2 are always successful.
AB - We have investigated the question: Do defibrillation thresholds (DFTs) vary during an episode of 'fibrillation,' and if so, what are the cellular mechanisms involved? Unstable microreentry ('fibrillation') and defibrillation (DF) shocks were simulated in a two-dimensional model of cardiac tissue on a massively parallel processor Connection Machine. The modelled tissue consisted of 16384 (128×128) 100 × 100 μm2 ventricular patches that obeyed modified Beeler-Reuter membrane kinetics. Reentry was initiated by stimulating the central region of the sheet during the repolarization phase of a passing planar wavefront. The DFT was then determined for several times following this premature stimulus. DFTs remained low (< 13 μA/cm2) until the initial figure-of-eight reentry degenerated into multiple unstable vortices (DFT ≈ 21 μA/cm2). Superimposed on this jump in DFTs was a small (±2.5 μA/cm2) quasi-periodic oscillation in DFTs whose average frequency correlated with the rotational frequency of the vortices. Therefore, we conclude that (1) there exists temporal variation in DFTs during fibrillation, (2) DFTs are lower during early fibrillation, and (3) DF shocks above ≈ 24 μA/cm2 are always successful.
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U2 - 10.1109/IEMBS.1992.5761142
DO - 10.1109/IEMBS.1992.5761142
M3 - Conference contribution
AN - SCOPUS:84944305427
T3 - Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS
SP - 626
EP - 627
BT - Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 1992
A2 - Plonsey, Robert
A2 - Laxminarayan, Swamy
A2 - Morucci, Jean Pierre
A2 - Coatrieux, Jean Louis
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 1992
Y2 - 29 October 1992 through 1 November 1992
ER -