Influence of channel blockers on cardiac alternans

Sudden cardiac arrest (SCA) due to fatal cardiac arrhythmias such as ventricular fibrillation is the leading cause of death in the United States, killing 350,000 Americans each year. Thus, it is of great importance to investigate the mechanisms that can suppress abnormal heart rhythms. In this work, we study the effects of drugs such as channel blockers through mathematical modeling of cardiac electrophysiological phenomena. In particular, we carry out multi-level simulations to study how channel blockers affect arrhythmias at cellular, fiber, and tissue levels. Numerical simulations show that the drugs have different effects at different scales (cellular versus fiber or tissue). Moreover, the drugs may appear to be arrhythmic in one model but antiarrhythmic in another. These observations indicate that analysis and simulation based on multiple scales and multiple models are crucial to fully understand the properties of drugs in treating arrhythmias.