Simulating the electrical behavior of cardiac tissue using the bidomain model.

The complex microstructure of cardiac muscle comprised of coupled cells, enveloped by an interstitium made up of blood vessels, connective tissue, and fluid, presents some obvious problems to those interested in understanding the tissue as an electrical medium. One approach that has gained considerable favor in recent years views the tissue not as a discrete structure, but rather as two coupled, continuous domains: one for the intracellular space and the other for the interstitial space. For convenience, the averaged potentials and currents in both domains are defined at every point in space. The structure is partially preserved by assigning a conductivity tensor at each point. One advantage of using this space-averaged model is that the governing equations for the electric fields can be described by partial differential equations that on occasion lead to analytical solutions. This formal treatment of cardiac tissue as two coupled continua is referred to as the bidomain model. This article presents a mathematical description of the bidomain model and reviews the use of the model for simulating the electrical behavior of cardiac tissue.