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DY: Fachverband Dynamik und Statistische Physik

DY 10: Focus session: Nonlinear Dynamics of the Heart I (organized by Markus Bär, Stefan Luther and Ulrich Parlitz)

DY 10.2: Vortrag

Mittwoch, 29. September 2021, 15:30–15:45, H6

The mechanism of defibrillation of cardiac tissue by time-periodic low-energy shocks I: Refractory boundary length is key for prediction of success probabilities — •Markus Bär, Pavel Buran, and Thomas Niedermayer — Physikalisch-Technische Bundesanstalt, Abbestr. 2 - 12, 10587 Berlin

Rotating excitation waves and electrical turbulence in cardiac tissue are associated with arrhythmias such as life-threatening ventricular fibrillation. Experimental studies have shown that a periodic sequence of four or more electrical far-field pulses is able to terminate fibrillation with less energy than a single shock protocol. During this so-called periodic low-energy anti-fibrillatory pacing (LEAP), only tissue near sufficiently large conduction heterogeneities, such as large coronary arteries, is activated. By means of simulation of the impact of periodic pacing on fibrillation in a two-dimensional electrophysiological model exhibiting multiple stable spirals (vortices) with a representative array of heterogeneities, we show that the success probability for defibrillation depends exponentially on the length of the refractory boundary, i. e. the total length of the borders between refractory and excitable parts of the tissue. This exponential dependency is also derived analytically from simple arguments assuming that successful defibrillation by a low energy shock requires not only to annihilate all vortices, but also needs to prevent initiation of new vortices in the vulnerable excitable region near the refractory boundary.