Mathematical model of reentry of cardiac excitation

A computer model of a ring-shaped cardiac fiber was used to examine responses of propagation to premature stimuli under different degrees of cell-to-cell coupling and membrane excitability. Nonsustained and sustained reentries were induced by a properly timed premature stimulus. The likelihood of inducing reentry is proportional to the degree of cellular uncoupling, demonstrating the importance of cellular uncoupling in the genesis of reentry. Alternans in action potential duration were also demonstrated during circus movement and were caused by the alternating kinetic properties of the slow ionic currents.