DOPPLER DUPLEX FOR THE EVALUATION OF THE DEGREE OF STENOSIS IN CAROTID ARTERIES IN THE RAT

This study evaluates the accuracy of the Doppler duplex technique for providing reliable information about the level of stenosis in microana stomoses. Stenoses ranging between 30 and 85 percent of the cross-sect ional area of carotid arteries were evaluated in rats. Peak systolic v elocities were measured in prestenotic, stenotic, and poststenotic seg ments, using the duplex technique. Surgical results with duplex measur ements were expressed as percentage of stenosis (calculated from a rat io of two cross-sectional areas), and later correlated. The correlatio n coefficient between the two sets of measurements was 0.82 (p < 0.01) , and the hypothesis of a simple linear relationship was clearly accep ted (p almost-equal-to 0.92). Results of the study show that duplex me asurements become increasingly unreliable in stenoses with severity le ss than 50 percent. With increasing degrees of stenosis (50 percent an d above), the variance of measurements with duplex decreases. Accordin g to the data, the limiting value for the duplex method appears to lie at about 85 percent. When methods for continuous measurement of flap perfusion indicate a hindrance of inflow, Doppler duplex can provide v aluable information about the causes. This technique can be used clini cally for the evaluation of microanastomoses in 1-mm vessels. In clini cal cases, if a 50 percent or more stenosis is diagnosed by duplex tec hnique, the measurement should be repeated within 1 to 2 hr. If the st enosis persists or intensifies, revision should be considered.