This project will improve the understanding of defibrillation mechanisms in the context of ischemia. Since a large fraction of cardiac arrhythmias occur in this setting, this is a significant clinical problem. The goal of this proposal is to develop a 3-D model of the rabbit ventricle and to study how the response of the heart to defibrillation shocks is altered by ischemia. This project could have an impact in the development of better defibrillators to prevent sudden cardiac death.