Anterior and posterior left ventricular sarcomere lengths behave
similarly during ejection.
Guccione, J. M., W. G. O'dell, A. D. McCulloch, and W. C. Hunter.
Department of Biomedical Engineering, The Johns Hopkins University,
School of Medicine, Baltimore, Maryland 21205-2195, Department of
Bioengineering, The University of California, San Diego, La Jolla,
California 92093-0412
APStracts 3:0328H, 1996.
Previous studies of regional differences in myocardial deformation
between the anterior and posterior walls of the canine left ventricle
were based on strain, which is not an absolute measure of
deformation. We thus compared sarcomere lengths at anterior and
posterior sites during ejection in isolated dog hearts.
Cin[acute]eradiographic imaging of regional deformation using
radiopaque markers implanted near midwall in five and just below the
epicardium in six hearts, combined with postmortem histology, allowed
sarcomere length reconstruction throughout the cardiac cycle. The
amount of sarcomere shortening accompanying left ventricular ejection
was similar in both walls of the left ventricle for sarcomeres
located at epicardial and midwall sites. The mean sarcomere length
(taken at the middle of the ejecting range) was also similar between
anterior and posterior sites, when averaging over all hearts. The
similarity of sarcomere function held not only at end-systole, but
throughout ejection, and over wide ranges of ventricular pre- and
afterloads. Hence, functional measurements of relative myocardial
shortening may not be indicative of regional sarcomere length
heterogeneity.
Received 14 February 1996; accepted in final form 2 July 1996.
APS Manuscript Number H154-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996