Computation of Heart Surface Potentials Using the Surface Source Model

Heart Surface Source Model. Introduction: The bidomain model of the heart leads to the result that the volume density of cardiac current source moment is proportional to the gradient of the macroscopic transmembrane action potential distribution. If the anisotropy ratios of the inner and outer domains (syncytia) of the myocardium are equal, then the volume distribution of cardiac sources can be replaced by an appropriate double layer on the heart surface. The double layer source distribution (heart surface source model) provides a basis for calculating heart surface potentials from cardiac sources. Methods and Results: The heart surface model was used to calculate epicardial potentials for the normal heart as well as for a case of ischemia and of infarction. The model was also used to determine the effect of insulating the heart surface. Insulating the heart surface caused an almost fourfold increase in peak‐to‐peak amplitude of simulated electrograms, with little change in waveshape. Simulated electrograms showed good agreement with recorded electrograms reported in the literature. Conclusion: The heart surface source model appears to provide a basis for relating heart surface potentials to the distribution of cellular action potential.