Extracellular potentials related to tortuosity and functional block in a two-dimensional model of ventricular myocardium

The authors investigate the relationship between the extracellular field shapes and the microscopic ultrastructure of the cardiac muscle. The effects of tortuosity, anisotropy and finite cytoplastic resistance on extracellular field patterns and propagation characteristics were studied. Tortuosity was induced by imposing dead cell strips parallel with the longitudinal direction. It was shown that multiple side peaks were associated with waves propagating through proximal corridors to the recording site. Also side peaks close to the main deflection were observed near functional block areas due to large local delays. The peak negative ionic current did not always coincide with the peak negative derivative of the extracellular fields. Increased anisotropy ratio combined with tortuosity caused macroscopic propagation speedup, while the inclusion of a finite cytoplasmic resistance caused a macroscopic propagation delay