Arterial Wall Motion and its Dynamic Modeling for Arterial Stiffness and Damping

Abstract

The pulsatile pressure in an artery is accompanied by the radial motion of the arterial wall. In this paper, the governing equation of the radial wall motion is first derived, indicating that longitudinal stretching of the arterial wall plays a critical role in the radial wall motion. Based on the derived equation and time-harmonic nature of its radial motion, the arterial wall is modeled as a second-order dynamic system. A microfluidic-based tactile sensor is used to acquire the arterial pulsatile pressure waveform, which is used to represent the radial displacement of the arterial wall. Consequently, the 1st-order and 2nd-order derivatives of the radial displacement are the wall velocity and wall acceleration. In the context of time-harmonic vibration, the key features in the radial displacement and its two derivatives are interpreted to obtain the elasticity and viscosity of the arterial wall: spring stiffness and damping coefficient in the circumferential direction. Pulse signals at radial artery (RA) and superficial temporal artery (STA) on seven healthy human subjects are measured and processed to estimate the two physical properties of the arterial wall. The measured difference in the physical properties between the two arteries and among the seven subjects validates the feasibility of the proposed dynamic modeling of the radial wall motion to capture the physical properties of the arterial wall, and at the same time demonstrates the necessity of subject-specific and artery-site-specific measurements.