Artery Wall Physical Properties as Clinical Indices for Detection of Atherosclerosis

Blood circulation in the cardiovascular system is essentially pulse wave propagation in the arterial tree. Pathological changes in the arterial wall alter its physical properties and undermine pulse wave propagation and eventually cause heart diseases. This study aims to establish a comprehensive engineering rationale for the influence of arterial wall physical properties on pulse wave propagation in an artery. The arterial wall is modeled as an initially-tensioned, isotropic, thin-walled tube. Flowing blood is treated as an incompressible, inviscid/viscous fluid. While the governing equations of flowing blood in the artery include the Navier-Stokes and continuity equations, the governing equations of the arterial wall motion arise from Newton’s second law and stress-strain relations. The boundary conditions at the blood-wall interface relate the flowing blood variables to the arterial wall variables. A free wave propagation analysis is conducted to derive the frequency equation. The solution to the frequency equation is two complex wave velocities (c1 and c2), representing the Young (c1) and Lamb (c2) waves propagating in the arterial tree. The real and imaginary components of each complex wave velocity provide the related wave velocity and transmission. With the related values at the carotid artery and the ascending aorta, the influence of arterial wall physical properties is obtained, and the physiological implications of such influence are also identified. The results illustrate clinical values of arterial wall physical properties on detection of arterial abnormalities, which may improve the utility of arterial wall physical properties as clinical indices for detection and treatment of atherosclerosis