Effect of extracellular calcium concentration on controlling cardiac alternans

Cardiac alternans may lead to life-threatening arrhythmias or sudden cardiac death. Thus, finding an effective method to suppress alternans is crucial. In this paper, we demonstrate that the time needed to control cardiac alternans induced by rapid pacing using the T+T-feedback control can be dramatically shortened if the extracellular calcium concentration is lowered by a very small amount when the control is turned on. Numerical simulations are performed on the Hund-Rudy dynamic (HRd) model for single cell. Since controlling alternans is important as it can be a precursor of sudden cardiac death, the results of our research may have important clinical implications and will lead to the development of a better control scheme for alternans or a smart defibrillator.