Key result
Larger graded action potential responses, longer action potential duration, or steeper APD restitution slope reduces the vulnerable window of cardiac reentry in simulated two-dimensional tissue.
In simulated cardiac tissue, larger graded responses, longer APD, and steeper APD restitution slopes reduce the vulnerable window for reentry by promoting wave tip annihilation or conduction block.
No immediate clinical implications for arrhythmia management; leaves open whether APD properties reduce reentry in vivo.
In normal heart, ventricular fibrillation can be induced by a single properly timed strong electrical or mechanical stimulus. A mechanism first proposed by Winfree and coined the "pinwheel experiment" emphasizes the timing and strength of the stimulus in inducing figure-of-eight reentry. However, the effects of cellular electrophysiological properties on vulnerability to reentry in the pinwheel scenario have not been investigated. In this study, we extend Winfree's pinwheel experiment to show how the vulnerability to reentry is affected by the graded action potential responses induced by a strong premature stimulus, action potential duration (APD), and APD restitution in simulated monodomain homogeneous two-dimensional tissue. We find that a larger graded response, longer APD, or steeper APD restitution slope reduces the vulnerable window of reentry. Strong graded responses and long APD promote tip-tip interactions at long coupling intervals, causing the two initiated spiral wave tips to annihilate. Steep APD restitution promotes wave front-wave back interaction, causing conduction block in the central common pathway of figure-of-eight reentry. We derive an analytical treatment that shows good agreement with numerical simulation results.
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Yang et al. (2007) studied Cardiac reentry / Ventricular fibrillation. Cellular electrophysiological properties (graded action potential responses, APD, APD restitution) was evaluated on Vulnerable window of reentry. Larger graded action potential responses, longer action potential duration, or steeper APD restitution slope reduces the vulnerable window of cardiac reentry in simulated two-dimensional tissue.
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