Computer simulation of arrhythmias in a network of coupled excitable elements

Area of Science:

• Computational biology
• Cardiac electrophysiology

Background:

• Cardiac arrhythmias are a significant cause of morbidity and mortality.
• Understanding the mechanisms of arrhythmia initiation and maintenance is crucial for developing effective therapies.

Purpose of the Study:

• To simulate and investigate the mechanisms underlying the initiation and maintenance of cardiac arrhythmias using a computational model.
• To explore the role of coupling, excitability, and refractory periods in generating complex electrical activity patterns.

Main Methods:

• Development of an interactive computer program to simulate coupled excitable elements in sheets and cables.
• Arbitrary adjustment of network geometry, element coupling, and cellular properties (excitability, automaticity, refractory period).
• Analysis of simulated electrical activity, including sustained repetitive activity and circus movements.

Main Results:

• Sustained repetitive activity and reciprocal activity were initiated and controlled by stimulation in models with critical coupling between automatic and non-automatic cells.
• Circus movements (vortices) were evoked in uniform sheets of coupled elements without the need for obstacles or refractory period dispersion.
• Vortices in homogeneous sheets involved elements inactivated by depolarizing currents from the wavefront; multiple vortices could coexist in larger sheets.

Conclusions:

• The study demonstrates that complex arrhythmias, including circus movements, can emerge from simple regenerative mechanisms in coupled excitable media under specific conditions.
• Computational modeling provides a powerful tool for dissecting the fundamental principles governing cardiac electrical activity and arrhythmia generation.