A Hypothesized Mechanistic Model of Longitudinal Wall Motion at the Common Carotid Artery

摘要

By adopting a physics-physiology integrative approach, this work hypothesizes a mechanistic model of longitudinal wall motion u_x(t) at the common carotid artery (CCA) and explores its antegrade amplitude u_(x0-ante) and retrograde amplitude u_(x0-retro) in systole for their clear implications. By examining the findings on u_x(t) and other relevant findings on the cardiovascular (CV) physiology in the context of the physical essence of u_x(t) and the CV system, a mechanistic model of u_x(t) is hypothesized and formulated as a boundary-value problem of nonhomogeneous wave propagation in a semi-infinite domain. With the aid of findings on u_x(t) and other related findings in the CV system, a scaling analysis of the boundary-value problem gives rise to two longitudinal arterial indices based on the two amplitudes: longitudinal elasticity E_(xx) at the CCA being estimated from u_(x0-ante), and u_(x0-retro) as an inverse indicator of the maximum base rotation of the left ventricle (LV) and a positive indicator of longitudinal elasticity at the ascending aorta (AA). The two arterial indices are qualitatively validated by their consistency with the effect of subclinical atherosclerosis and aging on the related parameters in the CV system. The implications of longitudinal elasticity to the LV function and energy transmission in the arterial tree are also discussed.