Mechanisms of reentry arrhythmia termination with ephaptic coupling and gap junctional coupling

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Cardiac Electrophysiology

Background:

• Cardiac cells rely on electrical communication via gap junctions for coordinated contractions.
• Conduction persists despite impaired gap junctions, suggesting alternative mechanisms like ephaptic coupling (EpC).
• The precise role of EpC in cardiac arrhythmias, particularly reentry, remains incompletely understood.

Purpose of the Study:

• To investigate the mechanisms by which ephaptic coupling (EpC) terminates reentry arrhythmias.
• To explore the interplay between EpC and gap junctional coupling in modulating cardiac conduction.
• To elucidate the underlying biophysical processes driving reentry termination under varying EpC levels.

Main Methods:

• Utilized a two-dimensional discrete bidomain model incorporating ephaptic coupling.
• Simulated cardiac electrical propagation across different levels of EpC and gap junctional coupling.
• Analyzed reentry dynamics and termination mechanisms under simulated conditions.

Main Results:

• Identified two primary mechanisms for reentry termination driven by EpC.
• Strong EpC terminates reentry via self-attenuation, linked to fast sodium current inactivation.
• Moderate EpC terminates reentry via self-collision, influenced by increased conduction velocity and anisotropy.
• A critical boundary was identified where reentry termination does not occur.

Conclusions:

• Ephaptic coupling plays a significant role in terminating cardiac reentry arrhythmias.
• The termination mechanisms are dependent on the strength of EpC and gap junctional coupling.
• Findings provide mechanistic insights into how EpC influences cardiac electrical stability and arrhythmia behavior.