Depressed regional deformation near the anterior papillary
muscle.
Holmes, Jeffrey W., Yasuo Takayama, Ian Legrice, and James W. Covell.
Departments of Bioengineering and Medicine, University of
California San Diego, La Jolla, California
APStracts 2:0092H, 1995.
The role of the papillary muscle in left ventricular function has
received new attention. We hypothesized that regional mechanics of
the left ventricular wall near the anterior papillary muscle are
influenced by the papillary muscle insertion. We therefore studied
three-dimensional regional mechanics in and near the anterior
papillary muscle (APM) in anesthetized, open chest dogs using
implanted radiopaque markers and biplane cineradiography. In seven
dogs, deformation differed little between an APM insertion site (PMA)
and a more basal site (PMB) overlying the APM. However, local
shortening and wall thickening were depressed in both locations
relative to anterior freewall sites (FWA, FWB) studied in five
additional dogs. A distinct structural border was observed at the
junction between the myocardial wall and APM which may preclude the
use of homogeneous strain in that region. Data from within the APM
indicated that uniaxial measurements in the papillary muscle are
extremely sensitive to the orientation of the measurement axis,
possibly explaining the variety of papillary muscle shortening
patterns reported by previous investigators.
Received 1 August 1994; accepted in final form 15 February 1995.
APS Manuscript Number H672-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.