Modelling induction of a rotor in cardiac muscle by perpendicular electric shocks

Abstract

A strong, properly timed shock applied perpendicularly to a propagating wavefront causes a rotor in the canine myocardium. Experimental data indicate that the induction of this rotor relies on the shock exciting tissue away from the electrodes. The computational study reproduced such direct excitation in a two-dimensional model of a 2.7 x 3 cm sheet of cardiac muscle. The model used experimentally measured extracellular potentials to represent 100 and 150 V shocks delivered through extracellular electrodes. The shock-induced transmembrane potential was computed according to two mechanisms, the activating function and the unit-bundle sawtooth potential. The overall process leading to initiation of a rotor was the same in model and experiment. For the 100 V shock, the directly excited region extended 2.26 cm away from the electrode; the centre of the rotor ('critical point') was 1.28 cm away, where the electric field Ecr was 4.54 Vcm(-1). Increasing the shock strength to 150 V moved the critical point 1.02 cm further and decreased Ecr by 0.39 Vcm(-1). The results are comparable with experimental data. The model suggests that the unit-bundle sawtooth is responsible for the creation of the directly excited region, and the activating function is behind the dependence of Ecr on shock strength.

Electrical Activity and Reentry During Acute Regional Myocardial Ischemia: Insights From Simulations

“…Since the first attempt by Moe et al [1963], many theoretical studies have used a modeling approach to understand and characterize different types of reentry in excitable media [Van Capelle & Durrer, 1980;Winfree, 1989;Leon et al, 1994;Starmer et al, 1995;Efimov et al, 1995;Rudy, 1995;Xu & Guevara, 1998;Biktashev et al, 1999;Ferrero, Jr. et al, 2000;Xie et al, 2001;Small et al, 2001;Skouibine et al, 2002;Bernus et al, 2002;among others]. However, the majority of these theoretical works have modeled the normal (non-ischemic) myocardium, with very few studies having dealt with the acutely ischemic myocardium, in which reentrant tachycardias and fibrillation are most likely to occur in vivo.…”

How the Spatial Frequency of Polarization Influences the Induction of Reentry in Cardiac Tissue

“…Recent studies have found that the small spatial scale heterogeneities in cardiac tissue may influence field stimulation and defibrillation 10–12,17–18 . Fishler represented the syncytial heterogeneities of cardiac tissue by varying the conductivities and the surface‐to‐volume ratio in the bidomain model 10 .…”

A comprehensive framework for evaluation of high pacing frequency and arrhythmic optical mapping signals

“…Monodomain simulations were performed using the openCARP simulation environment ( Plank et al, 2021 ) with baseline conductivity values of 0.03, 0.02 and 0.02 S/m for longitudinal ( σ L ), transverse ( σ T ) and transmural ( σ S ) directions. Using time steps of 0.05 ms throughout, a planar wave was generated by stimulating one transmural surface of the slab with shortening coupling intervals at 0, 325, 525 and 715 ms. A rotating wave was then generated by applying a cross field stimulus during the recovery phase of the central portion of the model at 860 ms ( Skouibine et al, 2002 ). To emulate experiments and signal morphology specific to optical mapping, the cardiac arrhythmia research package ( Vigmond et al, 2003 ) was used to generate epi-fluorescent optical signals from electrical simulations, as described previously ( Bishop et al, 2006 ).…”