Analysis of Multiplicative-Noise-Induced Effects in the Formation of Early Afterdepolarizations in a 4D Cardiomyocyte Model

We study a four-dimensional model of cardiac action potential which exhibits complex nonlinear dynamics. We introduce a stochastic version of this model with a multiplicative noise corresponding to random opening and closing of potassium channels. It is shown that in the parameter region where the initial deterministic system displays normal activity, noise can activate formation of pathological early afterdepolarizations. On the contrary, such abnormal oscillations can be inhibited by noise in other parameter zones. Phenomena of stochastic generation and suppression of early afterdepolarizations are investigated using direct numerical simulations with statistical postprocessing. Dynamical and probabilistic reasons for such noise-induced changes in behavior are discussed.