Presentation of a Non-invasive Method of Estimating Arterial Stiffness by Modeling Blood Flow and Arterial Wall Based on the Determination of Elastic Module of Arterial Wall

Abstract

Introduction: Arterial stiffness is an important predictor of cardiovascular risk. Several indices have been introduced to estimate the arterial stiffness based on the changes in the brachial blood pressure. Since the substitution of the blood pressure changes in the central arteries such as carotid with the blood pressure changes in the brachial results in error in the blood flow, it is of importance to present an elastic parameter based on the mechanical models without any reliance on the brachial blood pressure. Materials and Methods: Initially, a suitable dynamic model is introduced for pulsatile blood flow in the arteries based on Navier-Stokes the equations in fluid mechanics. Then, according to the theory of elasticity, the equations governing arterial wall are described and coupled with the equations of fluid flow. The attained system of equations is completed by the clinical information obtained from the carotid artery Doppler ultrasound images of healthy male subject. Therefore, the Doppler ultrasound images are recorded and saved in computer after which the center-line blood velocity, the arterial wall thickness, the period of a cardiac cycle and the arterial radius are measured by off-line processing. Results: The results from the analytic solution of the completed equations show that the elastic modulus for this healthy subject is 51 kpa which is in close agreement with the result obtained from other researches. Discussion and Conclusion: By applying this method, a non-invasive method of clinically evaluating the arterial stiffness will be possible by the Doppler ultrasound measurement of common carotid artery without any measurement of the local blood pressure.