Regional myocardial mechanical and electrical properties are dynamic and nonhomogeneous. Moreover they are coupled. Cardiac electrical excitation initiates mechanical contraction: excitation-contraction coupling. But mechanical factors also modulate myocardial electrical activity: mechano-electric feedback. Since these processes are also governed by the three-dimensional geometry and fibrous anisotropy of the ventricular walls, we have developed a continuum model of the three-dimensional anatomy, mechanical and electrophysiology of the rabbit heart. The model analyses have shown that the nonuniformity of myofiber orientation and the anisotropy of the myocardium play an important role in governing the regional distributions of myocardial stress and strain, activation and recovery. Experimental studies of regional electromechanical interactions in isolated and intact hearts have been performed to validate and extend these models. The continuum models provide a convenient framework to analyze and interpret the experimental measurements.
Finally, to facilitate the integration of biological models across scales of organization and function, a new resource has recently been established. The goal of the BioNOME Resource (BIOlogy Network Of Modeling Efforts) at the San Diego Supercomputer is to provide a repository of computational models for biological scientists and the tools to help them integrate and share their modeling efforts. Initially the resource will focus on two major areas: signal transduction and cardiovascular physiology.