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

Abstract

By adopting a physics-physiology integrative approach, this work hypothesizes a mechanistic model of longitudinal wall motion ux(t) at the common carotid artery (CCA) and explores its antegrade amplitude ux0-ante and retrograde amplitude ux0-retro in systole for their clear implications. By examining the findings on ux(t) and other relevant findings on the cardiovascular (CV) physiology in the context of the physical essence of ux(t) and the CV system, a mechanistic model of ux(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 ux(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 Exx at the CCA being estimated from ux0-ante, and ux0-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.