Geometrical Dynamics of Excitation in Heart Muscle and Chemical Models

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This multi-disciplinary venture involves physical chemistry of excitable gels, electrophysiology of normal heart muscle, bioengineering, and applied mathematics with emphasis on high-performance computation. It centers around the propagation of periodic activations from vortex lines in motionless 3-dimensional excitable media. In normal healthy heart muscle, such spontaneous and lethal periodicity can arise independently of any pathology, e.g., by electrical or mechanical shock. This "ventricular fibrillation" and its physical mechanisms have features in common with all other excitable media, for example "cold flames" in a chemical gel that propagates waves of color in 3 dimensions. Much is also learned from numerical experiments on the 3-dimensional partial differential equations of local reaction and diffusion that summarize both mechanisms (ionic channel dynamics and biolectric potential diffusion in one, chemical kinetics and molecular diffusion in the other.) All three have been under study in Dr. Winfree's laboratory for some years; the exchange of insights and analogies between them has been fruitful for all three areas, as testified by the -240 citations of these results annually as components of published investigations by others in diverse fields.