PHYSICAL MATHEMATICS SEMINAR

TOPIC:		ELECTRICAL WAVE PROPAGATION IN THE HEART:  
		THE DYNAMICS OF SCROLL WAVES IN ANISOTROPIC EXCITABLE MEDIA


SPEAKER:	SIMA SETAYESHGAR
		Firestone Laboratory
		California Institute of Technology

ABSTRACT:

There exists growing experimental evidence that fatal cardiac
arrhythmias can be associated with the formation and subsequent breakup of
spiral waves of electrical activity.  The goal of basic and applied
research in this field is a better understanding of the mechanisms
underlying the breakdown of coherent wave activity in the heart, leading
to improved schemes for prediction, control and treatment of cardiac
arrhythmias.

In this work, motivated by the rotation of fiber direction through the
thickness of cardiac tissue, we consider the asymptotic theory for the
dynamics of scroll waves in the presence of rotating anisotropy (rotation
of the fast axis of diffusion).  For the case of a straight scroll
filament, we have derived a phase equation which is given by Burgers'
equation with forcing due to the fiber rotation rate.  By considering a
special case of nonconstant fiber rotation rate, we have found an exact
solution which can have a finite-time twist singularity for certain
initial conditions.  This is the first analytical result pointing to the
destabilizing effect of cardiac tissue structure on scroll dynamics.  We
extend these results to include the coupling of filament motion to the
dynamics of the phase.

TIME:		TUESDAY, MAY 2, 2000

TIME:		2:30 PM

LOCATION:	Building 2, Room 338

Refreshments will be served at 3:30 PM in Building 2, Room 349.


						Massachusetts Institute of Technology
						Department of Mathematics
						Cambridge, MA  02139