Modeling ventricular repolarization gradients in normal cases using the equivalent dipole layer.

Area of Science:

• Cardiology
• Biophysics
• Computational Electrophysiology

Background:

• The electrical activity of the T-wave is not fully understood.
• Ventricular repolarization gradients are key to T-wave morphology.

Purpose of the Study:

• To investigate the relationship between normal T-wave morphology and underlying ventricular repolarization gradients.
• To simulate T-waves using the equivalent dipole layer (EDL) model.

Main Methods:

• Used body-surface-potential-maps (BSPM) from nine normal subjects.
• Created subject-specific MRI-based heart/torso models.
• Applied transmural, interventricular, and apico-basal repolarization gradients using EDL and boundary element method.
• Optimized combined gradients using an inverse procedure (Levenberg-Marquardt).

Main Results:

• Realistic T-waves were simulated when epicardial repolarization was faster than endocardial, left ventricle faster than right, and apex repolarization increased towards the base.
• The apico-basal gradient showed the highest correspondence (CC=0.84).
• Combined and optimized gradients yielded the best results (CC=0.96, RD=0.27).

Conclusions:

• Combining all repolarization gradients most accurately simulates measured T-waves.
• The apico-basal gradient is a significant contributor to T-wave morphology.
• Findings will optimize EDL-based inverse procedures for assessing repolarization abnormalities.