This talk presents an overview of the research conducted at the Computational Cardiac Electrophysiology Laboratory at the Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University. The projects range from cellular-level to multi-scale whole-organ simulations aimed at providing mechanistic insight into various problems in cardiac arrhythmogenesis and anti-arrhythmia therapies.  Projects include arrhythmogenesis under the conditions of ischemia phase 1A, mechano-electric feedback in the heart, studies on the mechanisms for ventricular defibrillation, the role of fibroblasts in conduction and defibrillation, and arrhythmia induction due to electroporation caused by strong shocks in the heart.