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RESEARCH PAPERS

Effect of Hypertension on Elasticity and Geometry of Aortic Tissue From Dogs

[+] Author and Article Information
Ramesh N. Vaishnav, Jafar Vossoughi

School of Engineering and Architecture, The Catholic University of America, Washington, D.C.

Dali J. Patel, LaVal N. Cothran, Bernell R. Coleman, Eleanor L. Ison-Franklin

Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, D.C. 20059

J Biomech Eng 112(1), 70-74 (Feb 01, 1990) (5 pages) doi:10.1115/1.2891128 History: Received February 09, 1989; Revised October 02, 1989; Online March 17, 2008

Abstract

Inflation-extension experiments were carried out on segments of the descending thoracic aortas from 4 normotensive and 4 hypertensive dogs rendered hypertensive using either unilateral or bilateral renal artery constriction. Intravascular pressures up to 200 mm Hg and axial forces up to 200 g were used. The external diameter of the segment and the distance between two longitudinally spaced gage marks were recorded photographically at each pressure-force level combination. Dimensions in the undeformed configuration were measured at the end of the inflation-extension experiment. Data were analyzed for changes in geometry and force-deformation response. Results indicate that: 1. Under sustained hypertension the wall thickness in the undeformed configuration increases with a concurrent reduction in the in-situ longitudinal extension ratio. 2. This dual tissue response accomplishes substantial reductions in the circumferential and longitudinal stresses from the levels that would be reached at equivlaent pressures in the absence of these geometric changes. 3. At comparable intravascular pressures the extensibility in the circumferential direction is slightly greater for the hypertensive aortas as compared to normals. However, the stress-extension ratio relationship in the circumferential direction is similar in the two groups. 4. The stress-extension ratio relationship in the longitudinal direction indicates that the hypertensive aorta is stiffer than its normotensive counterpart.

Copyright © 1990 by The American Society of Mechanical Engineers
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