An Integrated Data Acquisition and Processing System for Assessing Flow Disturbance Due to Arterial Consriction

Arterial constriction (stenosis) causes flow disturbance the level of which depends on the severity of constriction or degree of stenosis (DOS). Ultrasound Doppler signals obtained from poststenotic flow contain different frequencies depending on the mean flow velocity and velocity disturbance, the latter causing spectral broadening. A disturbance index defined as the ratio of quantified spectral broadening to mean frequency during a short sampling period around peak flow or in early deceleration phase, the so-called relative disturbance (RD), is expected to depend on DOS. Experiments were performed in vitro using pulsatile flow in a silicon rubber tube of 0.635 cm internal diameter as arterial model and silicon rubber stenosis models of different DOS. An 8-MHz pulsed Doppler ultrasound system was used to obtain Doppler (audio) signals from which the corresponding values of RD were calculated using Matlab software. The actual software were developed for an integrated system for data acquisition and processing in order to determine correlations between RD and DOS.