Influence of spatially modified tissue on atrial fibrillation patterns: Insight from solutions of the FitzHugh-Nagumo equations

TL;DR

This study uses the FitzHugh-Nagumo model to explore how spatial tissue inhomogeneities influence atrial fibrillation patterns, revealing mechanisms for fibrillatory states through dynamical pattern analysis and phase diagrams.

Contribution

It provides new insights into how tissue inhomogeneities and inter-region connections can induce fibrillatory states in cardiac tissue models.

Findings

Different dynamical patterns depend on inhomogeneity characteristics.

Phase diagrams quantify pattern occurrence based on inhomogeneity size and strength.

Fibrillatory states can be triggered by perturbations from connected regions.

Abstract

We study the interplay between traveling action potentials and spatial inhomogeneities in the FitzHugh-Nagumo model to investigate possible mechanisms for the occurrence of fibrillatory states in the atria of the heart. Different dynamical patterns such as ectopic foci, localized and meandering spiral waves are found depending on the characteristics of the inhomogeneities. Their appearance in dependence of the size and strength of the inhomogeneities is quantified by phase diagrams. Furthermore it is shown that regularly paced waves in a region R, that is connected by a small bridge connection to another region L with perturbing waves emanating from an additional pacemaker, can be strongly disturbed, so that a fibrillatory state emerges in region R after a transient time interval. This finding supports conjectures that fibrillatory states in the right atrium can be induced by self-excitatory pacemakers in the left atrium.