Clinical implications of pressure deformation analysis of curved elastic tubes

Abstract

The clinical implications of the pressure-deformation characteristics of a curved tapered elastic tube segment simulating the aortic arch without branches, subjected to an internal pressure, are presented. A finite-element technique was employed to analyse the asymmetrical deformation of the tube. Large deformation characteristics and the non-linear stress-dependent elastic stiffness property of the vessel wall were incorporated by a step-wise incremental analysis method, with a linear small deformation finite-element formulation being employed for the analysis at each time step increment.

For a healthy vessel, simulated by uniform Young's modulus against stress characteristics, and a simulated arteriosclerotic vessel (having some wall segments with elevated Young's modulus against stress characteristics), the distributions of the deformations, wall stress and compliance were determined during the cardiac cycle, and graphically illustrated. The results enabled us to appreciate the sensitivity and utility of pressure-deformation characteristics to distinguish between healthy and arteriosclerotic vessels.

The methodology can be employed to generate pulse pressure-deformation patterns which, by comparison with fluoroscopically or echocardiographically monitored deformation patterns, may help determine the distribution of the stress-dependent Young's modulus of the vessel wall. This technique may provide a tool for the detection of arteriosclerosis in the human circulatory system especially with the recent developments in the image-processing techniques, such as videodensitometric analysis.