AJP - Heart and Circulatory Physiology, Vol 244, Issue 1 3-22, Copyright © 1983 by American Physiological Society
The nature of electrical propagation in cardiac muscle
M. S. Spach and J. M. Kootsey
It has long been appreciated that cardiac muscle is composed of individual
cells connected by low-resistance connections, but most concepts of cardiac
impulse conduction have been based on a simplified model of propagation
assuming continuously uniform intracellular resistivity in the direction of
propagation. In this article we describe the development of the application
of the theory of continuous media to propagation in cardiac muscle and
review some of the successes achieved with this theory. New evidence is
cited that propagation in cardiac muscle often displays a discontinuous
nature. We consider the hypothesis that this previously unrecognized aspect
of propagation can be explained by discontinuities in axial resistance
related to known structural complexities of cardiac muscle. A major
implication is that the combination of discontinuities of effective axial
resistivity at several size levels can produce a wide variety of complex
abnormalities of propagation, including most currently known cardiac
conduction disturbances that have been considered to require spatial
nonuniformity of membrane properties.
