Virtual electrode polarization leads to reentry in the far field

Area of Science:

• Cardiac Electrophysiology
• Computational Cardiology
• Arrhythmia Mechanisms

Background:

• Previous work explored cardiac vulnerability to reentry in the near field using the virtual electrode polarization (VEP) concept.
• This study extends the VEP concept to the far field and compares its predictive power to the critical point hypothesis.

Purpose of the Study:

• To investigate far-field virtual electrode polarization (VEP) effects on cardiac vulnerability.
• To compare VEP predictions with the critical point hypothesis in cardiac tissue simulation.
• To elucidate mechanisms of reentry initiation and propagation under different stimulation conditions.

Main Methods:

• Simulated electrical activity in a two-dimensional bidomain model of myocardium with experimentally derived rabbit heart fiber directions.
• Applied S1 and S2 stimuli (cathodal or anodal line electrode) to induce and study reentry.
• Analyzed reentry initiation (break/make excitation) and rotor dynamics across various coupling intervals (CIs) and stimulus strengths.

Main Results:

• Observed a far-field VEP pattern across the entire myocardial sheet, consistent with experimental findings.
• Reentry was initiated via break excitation, make excitation, or both, propagating through recovered tissue.
• For long coupling intervals (CIs) above the minimum make excitation CI, reentry dynamics aligned with the critical point hypothesis for cathodal S2 stimuli.

Conclusions:

• Shock-induced virtual electrode polarization (VEP) effectively explains cardiac vulnerability in the far field.
• The VEP theory of vulnerability integrates the critical point hypothesis for specific conditions (cathodal S2 shocks at long CIs).