The Cardiac Imaging research line is about innovative imaging methodologies to increase the understanding of cardiac physiology. For instance, we developed an ultrafast random-access multi-photon (RAMP) microscope that is used to simultaneously measure action potentials and intracellular calcium transients at multiple sites within the sarcolemma of cardiac cells. A wide-field mesoscope was also developed to optically map and manipulate action potential propagation in whole mouse hearts. The mesoscope was implemented with 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 combined in correlative manner with whole heart cytoarchitecture. In this project, 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.