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

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.