Virtual electrodes around anatomical structures and their roles in defibrillation

Area of Science:

• Computational electrophysiology
• Biophysics of cardiac tissue

Background:

• Virtual electrodes arise from structural and conductivity heterogeneities in cardiac tissue.
• These virtual electrodes are crucial for understanding wavefront propagation and defibrillation efficacy.

Purpose of the Study:

• To investigate how anatomical and conductivity parameters of heterogeneities affect virtual electrode patterns.
• To analyze the influence of endocardial, epicardial, and intramural surfaces (blood vessels) on virtual electrode formation.

Main Methods:

• Utilized the steady-state bidomain model for analysis.
• Employed both analytical and numerical methods to derive virtual electrode patterns.
• Modeled idealized endocardial trabeculations and blood vessels.

Main Results:

• Virtual electrode patterns around blood vessels result from current traversing the vessel surface and fiber-architecture conductivity heterogeneity.
• The observed swapping of virtual electrode polarity with vessel radius is explained by the interplay of these two effects.
• Higher blood conductivity leads to stronger depolarization in endocardial trabeculae grooves compared to protrusions.

Conclusions:

• Provides quantitative insights into virtual electrodes generated by small-scale ventricular anatomy.
• Emphasizes the necessity of accurate physiological and physical representation in computational modeling for field stimulation.