The advent of optogenetics and three-dimensional optical imaging grants us the unique opportunity to more specifically examine targeted defibrillation methodologies on a more holistic level. In this project, we are studying mechanisms underlying defibrillation to show the efficacy of selective stimulation of the excitable gap in ventricular tachycardia and fibrillation termination in a 3D ex vivo mouse model using optogenetics and panoramic optical mapping.