19 September 2008
Jeffrey Fox
Vice President
Cardiovascular Research
Gene Network Sciences
Ventricular fibrillation (VF), a heart rhythm disorder that prevents the normal contraction of the ventricles, remains a leading cause of death in the United States. Although there currently is some controversy concerning the exact mechanism for VF, all hypotheses for fibrillation invoke wave break and conduction block, secondary to spatial heterogeneity of cardiac electrical properties. Heterogeneities may arise from intrinsic properties of the tissue, or they may be dynamically induced. This talk will describe a simple coupled-maps model of 1D cardiac fibers that has been used to identify the key determinants of dynamic heterogeneity. Certain sequences of premature stimuli were found to induce spatial heterogeneity and conduction block in the simple 1D model. Recent experimental studies have supported these predictions; sequences of premature stimuli chosen to maximize dynamic heterogeneity induced VF in canine experiments. Finally, the talk will discuss more detailed ionic models of cardiac tissue, and will briefly describe simulations of wave break and arrhythmia in realistic three-dimensional models of the canine ventricular anatomy.