Key result
The stability and dynamics of spatially discordant alternans nodes are determined by the balance of tensions from conduction velocity restitution, convection, curvature, and heterogeneities.
Why the study?
Cardiac alternans is a precursor of ventricular arrhythmias and sudden cardiac death, prompting investigation into the stability and dynamics of nodes and nodal lines of repolarization alternans driven by voltage instabilities.
This computational study provides mechanistic insights into the behaviors of spatially discordant repolarization alternans, a precursor to ventricular arrhythmias, by identifying the factors that determine the stability of nodal lines.
Findings on SDA node stability are hypothesis-generating; leaves open whether modulating these tensions prevents arrhythmias in vivo.
Cardiac alternans, a period-2 behavior of excitation and contraction of the heart, is a precursor of ventricular arrhythmias and sudden cardiac death. One form of alternans is repolarization or action potential duration alternans. In cardiac tissue, repolarization alternans can be spatially in-phase, called spatially concordant alternans, or spatially out-of-phase, called spatially discordant alternans (SDA). In SDA, the border between two out-of-phase regions is called a node in a one-dimensional cable or a nodal line in a two-dimensional tissue. In this study, we investigate the stability and dynamics of the nodes and nodal lines of repolarization alternans driven by voltage instabilities. We use amplitude equation and coupled map lattice models to derive theoretical results, which are compared with simulation results from the ionic model. Both conduction velocity restitution induced SDA and non-conduction velocity restitution induced SDA are investigated. We show that the stability and dynamics of the SDA nodes or nodal lines are determined by the balance of the tensions generated by conduction velocity restitution, convection due to action potential propagation, curvature of the nodal lines, and repolarization and coupling heterogeneities. Our study provides mechanistic insights into the different SDA behaviors observed in experiments.
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Huang et al. (2020) studied Cardiac alternans. Computational modeling was evaluated on Stability and dynamics of spatially discordant alternans nodes or nodal lines. The stability and dynamics of spatially discordant alternans nodes are determined by the balance of tensions from conduction velocity restitution, convection, curvature, and heterogeneities.
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