A HYPOTHESIZED MECHANISTIC MODEL OF LONGITUDINAL WALL MOTION AT THE COMMON CAROTID ARTERY

In light of recently recognized independent clinical values of longitudinal wall motion u(x)(t) at the common carotid artery (CCA) and the struggle on appropriate arterial indices for interpreting u(x)(t), this paper hypothesizes a mechanistic model of u(x)(t) and explores clear implications of the antegrade amplitude u(x0-ante) and retrograde amplitude u(x0-retro) of u(x)(t) in systole to the cardiovascular (CV) system. By examining findings on u(x)(t) and other relevant findings through the lens of the engineering essence of u(x)(t), a mechanistic model of u(x)(t) is hypothesized: the left ventricle (LV) base rotation is the excitation source for initiating the longitudinal elastic wave propagating along the arterial tree; wall shear stress at an artery serves as a local external source for supplying energy to the longitudinal elastic wave; and longitudinal elasticity at the arterial wall dictates the wave propagation velocity. Integrating the mechanistic model with findings on ux(t) gives rise to interpretation of u(x0-ante) and u(x0-retro) for their clear implications: longitudinal elasticity E-xx at the common carotid artery (CCA) is estimated from u(x0-ante), and u(x0-retro) is an inverse indicator of the maximum base rotation of the LV and a positive indicator of longitudinal elasticity at the ascending aorta (AA). For the first time, this model reveals the mechanisms underlying those statistical-based findings on u(x)(t).