The need to account for residual strains and the composite nature
of the heart wall in mechanical analyses.
Kang, T, and Yin, F. C. P.
Departments of Medicine and Biomedical Engineering, The Johns
Hopkins Medical Institutions, Baltimore, Maryland 21205
APStracts 3:0008H, 1996.
We studied 19 excised, passive rabbit left ventricular walls to
delineate the forms of the strain energy functions (W) for myocardium
and epicardium, to quantify residual strains across the wall, and to
investigate whether the mechanical behavior of the intact wall can be
predicted by accounting for the above properties. The unloaded
dimensions and the stress-strain responses to equibiaxial and
uniaxial loadings were obtained first for the intact wall and then
individually for the epicardium and myocardium. Results show that the
previously proposed W's for canine myocardium and epicardium are
suitable. The unloaded intact wall has residual strains: the
epicardium is stretched and the myocardium is shrunk from their
respective isolated, unloaded states. The predicted mechanical
responses of the intact wall to biaxial loadings were inaccurate when
the residual strains were not taken into account. Accounting for
these, however, yielded reasonable predictions. Thus, information on
the unloaded reference state and properties of each portion are
needed to accurately predict the behavior of the intact wall.
Received 19 December 1994; accepted in final form 19 December
1995.
APS Manuscript Number H1109-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96