A numerical reconstruction of the effects of late stimulation on a cardiac ventricular action potential

Numerical simulations of a propagating cardiac action potential utilizing Beeler-Reuter and Drouhard-Roberge physiological routines for the membrane current have been performed. These action potentials show increases in action potential duration when subjected to strong late stimuli of either positive or negative polarity. The mechanism is the same as that reported in an earlier paper which utilized a different physiological approach: repolarizing stimuli can reset the fast sodium gates locally so that they can be retriggered by diffusive return of charge from surrounding tissue. This results in a large depolarizing transient that lengthens action potential duration.