Simple model for identifying critical regions in atrial fibrillation

Area of Science:

• Computational biology
• Cardiac electrophysiology
• Medical physics

Background:

• Atrial fibrillation (AF) is a prevalent heart rhythm disorder and a major stroke risk factor.
• Current ablation therapies for AF have limited clinical success due to empirical approaches.
• Understanding the mechanisms of AF initiation and maintenance is crucial for developing effective treatments.

Purpose of the Study:

• To develop a simplified model of cardiac electrical activity to understand AF mechanisms.
• To identify critical regions in the atria responsible for AF initiation and maintenance.
• To analytically determine the threshold for AF emergence and its dependence on physiological parameters.

Main Methods:

• A simple model of activation wave front propagation on an anisotropic cardiac tissue structure was designed.
• The model integrates phenomenological dynamics with structural properties of heart muscle cells.
• Analytical calculations were performed to assess arrhythmia risk and threshold parameters.

Main Results:

• AF spontaneously emerges when transverse cell-to-cell coupling decreases below a critical threshold, mimicking age-related changes.
• Specific critical regions responsible for AF initiation and maintenance were identified.
• The threshold for AF emergence was analytically expressed as a function of model parameters, decreasing with increased refractory period.

Conclusions:

• The model provides insights into AF emergence linked to reduced cell coupling and identifies key regions for ablation.
• Analytical predictions regarding the threshold for AF and the role of the refractory period offer testable hypotheses.
• These findings may guide the development of more targeted and effective AF ablation strategies and risk assessment tools.