Vol. 279, Issue 5, H2519-H2528, November 2000
Active and passive stresses in the myocardium
Rachad M.
Shoucri
Department of Mathematics and Computer Science, Royal Military
College of Canada, Kingston, Ontario, Canada K7K 7B4
A
mathematical approach that can be used to calculate the passive stress
in the ventricular wall is presented. The active fiber stress
(force/unit area) generated by the muscular fibers in the ventricular
wall is expressed by means of body force (force/unit volume of the
myocardium). It is shown that the total intramyocardial passive stress
induced in the passive medium of the myocardium can be expressed as the
sum of a passive stress induced by the left ventricular pressure and a
passive stress induced by the active fiber stress. Applications to
experimental data published in the literature are given. New results
are presented that show the relation among those two components of the
intramyocardial passive stress. New relations between the
intramyocardial passive stress, the slope (elastance) of the
pressure-volume relation, and the residual volume are also derived. The
results obtained give a better understanding of some aspects of the
mechanics of cardiac contraction and can provide a more detailed
interpretation of clinical conditions.
stress-strain relations; end-systolic pressure-volume
relation, maximum left ventricular elastance; cardiac mechanics; residual volume; Law of Laplace
