The cardiac imaging group develops innovative optical imaging methodologies to increase the understanding of cardiac physiology. Random access multi-photon microscopy was developed and used to simultaneously measure action potentials and intracellular calcium transients at multiple sites within the sarcolemma in health and diseased cardiac cells. Taking this work to another order of magnitude, our lab is also investigates action potential propagation at the whole heart level. In this respect, we developed an optical system capable of mapping and controlling the action potential propagation in perfused hearts. The system was implemented with a digital micromirror device capable of drawing arbitrarily-chosen stimulation patterns allowing precise epicardial optogenetic stimulation. Recently, a real-time manipulation of the propagating electrical wave-front has been demonstrated, opening the prospect for real-time resynchronization therapy and cardiac defibrillation. Functional studies are also combined in a correlative manner with whole heart cytoarchitecture. We combine advances in high-resolution optical microscopy, tissue clearing (CLARITY based), and immunostaining to reconstruct the three-dimensional organization of the cardiac conduction system in the whole mouse heart.