Deciphering Arrhythmia Mechanisms: Tools of the Trade

Pathophysiological remodeling of cardiac function occurs at multiple levels, spanning the spectrum from molecular and subcellular changes to those occurring at the organ-system level. Of key importance to arrhythmias are changes in electrophysiological and calcium handling properties at the tissue level. This review discusses how high-resolution optical mapping of action potential and calcium transients has advanced our understanding of basic arrhythmia mechanisms associated with multiple cardiovascular disorders, including the long QT syndrome, heart failure, and ischemia-reperfusion injury. The article focuses on the role of repolarization gradients and calcium-mediated triggers in the initiation and maintenance of complex arrhythmias in these settings.