Effect of interstitial anisotropy and the extracellular volume conductor on action potential morphology in a thin layer of cardiac tissue

We simulated conduction in a thin layer of cardiac tissue using both a bidomain and monodomain model of the structure. The two models predict similar wavefronts and action potential shapes when the intracellular and interstitial spaced are both insulated. The most significant differences in active tissue are observed in the foot of the transmembrane potential, the portion of the upstroke due to passive current flow. The two models yield markedly different behavior when the interstitial space is not insulated but permitted to exchange currents with a thin layer of bounding fluid.