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Postshock Recovery Interval of Relatively Refractory Myocardium as a Possible Explanation for Disparate Defibrillation Efficacy Between Monophasic and Biphasic Waveforms
Author(s) -
MURAKAWA YUJI,
YAMASHITA TAKESHI,
SEZAKI KAZUNORI,
KANESE YUKIHIRO,
OMATA MASAO
Publication year - 1998
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1998.tb00184.x
Subject(s) - refractory period , defibrillation , medicine , waveform , cardiology , stimulus (psychology) , refractory (planetary science) , electrophysiology , pulse duration , anesthesia , voltage , optics , psychology , laser , physics , astrobiology , psychotherapist , quantum mechanics
We investigated the electrophysiological background for the waveform related variability of defibrillation efficacy. In 22 open‐chest dogs, a localized potential gradient was created using an 8‐V or 16‐V field stimulus across a pair of plate electrodes separated by 5 mm. The postshock recovery interval of the nonde‐polarized myocardium adjacent to the excited area was estimated by the residual refractory period after an appropriately timed field stimulus. The postshock recovery interval and the defibriliation threshold were compared among six different waveforms but with the same total duration of 12 ms (n = 11) or 16 ms (n = 11). Six defibriliation thresholds in individual hearts showed a significant inverse correlation with postshock recovery intervals in most dogs (8/11 tested with a total pulse duration of 12 ms (8 V stimulus: r = ‐0.80 ± 0.20 [n = 11]). In contrast, waveforms with a total duration of 16 ms failed to reveal this distinct relationship. We conclude that the waveform related variability of defibrillation efficacy is associated with the refractoriness of relatively refractory myocardium when the total pulse duration is within a certain range. However, the mechanisms responsible for waveform performance may vary as the total pulse duration changes.