Simple and noninvasive analysis of the pulse wave for blood vessel evaluation

The pulse wave is a good indicator to evaluate the viscoelastic properties of blood vessels. The wave is composed of an incident wave and a reflected wave. Since the reflected wave is generated by the reflection of the incident wave at the peripheral artery after propagating long distance along blood vessels, the characteristics of that wave depend remarkably on arterial stiffness. Therefore, the evaluation of arterial stiffness may be possible from the analysis of this reflected wave. In this study, we propose a simple and noninvasive technique to estimate the reflected wave from the pulse wave observed at common carotid artery, making use of a commercial piezoelectric transducer and an ultrasonic diagnostic equipment. First, we estimated the incident wave from the blood flow velocity waveform. Then, the reflected wave was obtained by subtracting the incident wave from the pulse wave. As a result, the maximum values of the reflected wave increased with advancing age. This result was in good agreement with the increasing elasticity of blood vessels due to age.