Professor John P. Wikswo
Vanderbilt University
Nashville, Tennessee

Monday, April 30, 2001
3:00 pm (CT)
3269 Beckman Institute

Abstract

The human heart is a biochemically powered, electrically activated, nonlinearly controlled, pressure- and volume-regulated, two-stage, tandem, series-connected mechanical pump with a mean time-to-failure of approximately 2x10^9 cycles. The cardiac spatial scales range from the ten- centimeter diameter of the entire heart to the nanometer pore of gated ion channels, while the time scales range from the one-second heart beat and the many seconds of a complex arrhythmia to the nanosecond conformational changes of protein channels, i.e., a factor of 10^24 in volume and 10^9 in time. Phenomena at the spatial scale of 0.1 to 1 mm are dominated by the electrical anisotropy of cardiac tissue, most obviously manifested by the two- fold difference in conduction velocity of electrical trigger waves traveling parallel or perpendicular to the cardiac fiber axis. This is the result of larger but more difficult-to-detect anisotropies of the electrical conductivities of the intracellular and extracellular spaces. We describe models and experiments that explore and exploit these anisotropy differences and provide a new window into the nonlinear dynamics of cardiac tissue, scroll waves, and phase singularity kinematics.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.