Estimation of reflected wave in carotid pulse wave for simple and noninvasive assessment of arterial stiffness

Evaluation of a pulse wave is effective for screening arteriosclerosis. The pulse wave is composed of two components, incident and reflected waves. Because attenuation of the reflected wave changes markedly due to the arterial stiffness, analyzing this wave is useful. In previous study, we proposed a separation technique of two components using observed pulse waves and blood flow velocity waveforms. We confirmed that maximum values of estimated reflected waves increased with age. However, the measurement of the blood flow still needs an ultrasonic diagnostic equipment, which results in a barrier for simple screening. In this study, empirical model functions of blood flow velocity are introduced for each age group. The functions were obtained by averaging the blood flow velocity waveforms after normalizing them by the time interval between maximum amplitude and incisura. We then investigated the applicability of these functions for the estimation of the reflected waves. In consequence, we found small differences between the amplitudes of reflected waves estimated by personal waveform and empirical model function. The idea of this empirical model function is reasonable and eliminates the use of ultrasonic diagnostic system.