AJP - Heart and Circulatory Physiology, Vol 257, Issue 4 1165-H1173, Copyright © 1989 by American Physiological Society

ARTICLES

Nonuniform shortening of the anterior wall of feline left ventricles

E. Hexeberg, K. Matre, S. Birkeland and J. Lekven
Department of Surgery, University of Bergen, Haukeland Hospital, Norway.

Recorded performance of segments between implanted ultrasonic crystals placed at midwall position of the left ventricle reportedly depends almost exclusively on midwall function and alignment with fibers. Accordingly, one would expect the ratio between performance of a segment perpendicular to midwall fiber direction (transverse) and a parallel segment (longitudinal) to be constant and independent of changes in preload, afterload, and the inotropic state. We tested this hypothesis by implanting cross-oriented crystal pairs in nine open-chest cats and studied their performance during preload and afterload changes with and without isoproterenol infusion. Fiber orientation across the ventricular wall was determined by serial histological sectioning. The ratio between performance of transverse and longitudinal segments (trans/long) changed with interventions. Increased end-diastolic pressure leads to increased segment performances as well as trans/long. Inotropic stimulation produced increased sensitivity to preload changes both for individual segment performances and for trans/long. These results suggest that longitudinal segments represent the function of midwall fibers, whereas transverse segments may well represent the function of sub-endocardial fibers, which run closer to this orientation. Thus trans/long provides a way to quantify nonuniformity of local myocardial contraction.

This article has been cited by other articles:

				H. Brunv and a. K. Grong Carvedilol Retards Sudden Loss of Contraction during Early Regional Myocardial Ischemia in Feline Hearts J. Pharmacol. Exp. Ther., July 1, 1997; 282(1): 363 - 368. [Abstract] [Full Text]