Local onset of voltage and calcium alternans in the heart

A beat-to-beat variation in cardiac action potential durations (APD) is a phenomenon known as electrical alternons. Alternons desynchronizes depolarization, increases dispersion of refractoriness and creates a sub strate for ventricular fibrillation. In the heart, APD alternons can be accompanied by alternons in intracellular calcium ([Ca²⁺]_i) transients. Recently, we demonstrated experimentally that the onset of APD alternons in the heart is a local phenomenon that undergoes complex spatio temporal dynamics as pacing rate increases. Moreover, the local onset of APD alternons can be predicted by measuring the restitution properties of periodically paced cardiac tissue. The purpose of this research is to investigate the interplay between local onsets of APD and [Ca²⁺]_i alternons using 2D simulation of action potential model of cardiac myocytes.