Ventricular arrhythmias including ventricular tachycardia (VT) and ventricular fibrillation (VF) are responsible for 300,000 sudden cardiac deaths a year in the US. Electrotherapy has been effective in arresting VT/VF but the high-energy biphasic shocks can lead to myocardial damage and associated co-morbidities. Moreover the implantable cardioverter defibrillator technology (ICD) has low VT/VF sensing resolution, which can lead to inappropriate shocks and associated psychological distress, resulting in diminished quality of life or even death. Thus, there is an unmet need for high-definition VT/VF sensing to reduce inappropriate shocks and similarly, an unmet need for high-definition ultra-low energy electrotherapy to terminate VT/VF. In this project, we present a novel approach to VT/VF sensing and electrotherapy and redesign the ICD into cardiovascular implantable electronic device (CIED). We will employ two break-through technological platforms to implement our novel method: (1) A novel organ conformal bioelectronics real-time networks (OCBERN) technology developed by Co-Investigator Dr. Rogers and an (2) innovative panoramic, transillumination optical mapping developed by PI Dr. Efimov. We will conduct high-definition, panoramic, transillumination, optical mapping in conjunction with high-definition OCBERN to (1) characterize the transmural VT/VF dynamics, (2) determine the optimal number of sensors needed to dynamically track the excitable gaps, phase singularities, and wavefronts during VT/VF, and (3) terminate VT/VF using optimal definition ultra-low-energy high-definition electrotherapy. This proposed work would advance our understanding of VT/VF and pave the path towards creating a targeted individualized therapy dynamically tailored for each arrhythmia episode for each patient.