This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project aims to perform simulations of the blood-muscle-valve mechanics and electrophysiology of the heart, with the goal of performing coupled simulations of cardiac mechanics, fluid dynamics, and electrophysiology. Although the equations that describe cardiac mechanics and electrophysiology are different, we employ a common theoretical framework, the immersed boundary (IB) method, to model both aspects of heart function. The IB method was introduced as an approach to problems of fluid-structure interaction (e.g., cardiac fluid mechanics), but we have extended it to describe cardiac electrophysiology. We have developed a unified software implementation of the IB approach to both cardiac mechanics and electrophysiology. This simulation framework provides support for distributed-memory parallelism and spatial adaptivity, thereby allowing us to use modern supercomputers effectively and efficiently. This project aims to use this simulation framework (1) to perform multi-beat, whole-heart simulations of cardiac electro-mechanics, (2) to perform extremely high resolution multi-beat simulations of blood flow through a model of the human aortic valve, and (3) to perform high resolution adaptive bidomain simulations of normal and pathophysiological ventricular electrophysiology. Within the present project, we also aim to perform substantial code optimization, and to begin work on extending this software to use a hybrid parallel programming model that employs OpenMP for intra-nodal parallelism and MPI for inter-nodal parallelism.