Event
Special Bioengineering Seminar: Jeffrey Fox
Thursday, April 2, 2009
11:00 a.m.-12:00 p.m.
Room 1107, Jeong H Kim Engineering Building
Professor Elias Balaras
balaras@umd.edu
Multi-Scale Modeling of Cardiac Electrophysiology: Dynamic Heterogeneity, Conduction Block, and Reentry
Presented by Dr. Jeffrey Fox
Visiting Scientist
Center for Applied Mathematics
Cornell University
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. It has been shown that dynamic heterogeneity and conduction block can be induced in 1D models of cardiac tissue by launching a series of rapid, irregular excitations, similar to those often observed clinically prior to onset of VF. In these simulations, dynamically induced heterogeneities led to a wave block that annihilates wave propagation. However, experimental investigations of similar stimulus patterns in the intact canine indicate that stimuli chosen to maximize dynamic heterogeneity induce VF, rather than complete wave block. Recently we have shown that boundary-induced modifications of action potential duration are sufficient to disrupt conduction block and induce unidirectional propagation in 1D when stimulus intervals that maximize dynamically induced heterogeneity are applied. However, 3D simulations are needed to test if these behaviors occur in realistic anatomies. To that end, we simulated wave propagation in a 3D model of the canine ventricular anatomy. Preliminary results suggest that block is induced by the premature sequence, but the portion of the wave near the boundary survives, leading to reentry.
