Radial and Axial Motion of the Initially Tensioned Orthotropic Arterial Wall in Arterial Pulse Wave Propagation

Abstract

Abstract With the arterial wall modeled as an initially tensioned thin-walled orthotropic tube, this study aims to analyze radial and axial motion of the arterial wall and thereby reveal the role of axial motion and two initial tensions of the arterial wall in arterial pulse wave propagation. By incorporating related clinical findings into the pulse wave theory in the literature, a theoretical study is conducted on arterial pulse wave propagation with radial and axial wall motion. Since the Young wave is excited by pulsatile pressure and is examined in clinical studies, commonly measured pulsatile parameters in the Young wave are expressed in terms of pulsatile pressure and their values are calculated with the well-established values of circumferential elasticity (Eθ) and initial tension (Tθ0) and assumed values of axial elasticity (Ex) and initial tension (Tx0) at the ascending aorta and the carotid artery. The corresponding values with the exclusion of axial wall motion are also calculated. Comparison of the calculated results between inclusion and exclusion of axial wall motion indicates that (1) axial wall motion does not affect radial wall motion and other commonly measured pulsatile parameters, except wall shear stress; (2) axial wall motion is caused by wall shear stress and radial wall displacement gradient with a factor of (Tx0−Tθ0), and enables axial power transmission through the arterial wall; and (3) while radial wall motion reflects Eθ and Tθ0, axial wall motion reflects Ex and (Tx0−Tθ0).