Evaluation of the Tardus-Parvus Pattern in Patients With Atherosclerotic and Nonatherosclerotic Renal Artery Stenosis

OBJECTIVE The aim of this study was to evaluate the differences in the tardus-parvus pattern between atherosclerotic and nonatherosclerotic renal artery stenosis (RAS) and to explore the causes of these differences. METHODS In 81 patients, including a nonatherosclerotic group (29 cases of Takayasu arteritis and 22 cases of fibromuscular dysplasia) and an atherosclerotic group (n = 30), RAS was detected by color Doppler sonography and confirmed by renal arteriography. Doppler spectra were obtained at the upper, middle, and lower pole interlobar arteries, and the one with the most prolonged acceleration time (AT) was selected for recording the AT and resistive index (RI). RESULTS Renal angiography revealed 16 moderate RASs, 80 severe RASs, and 15 occlusions. No statistically significant differences were found in the AT between the atherosclerotic and nonatherosclerotic groups in the mild (P = .24), moderate (P = .63), and severe stenotic (P = .41) subgroups; however, there were statistically significant differences in the RI between the atherosclerotic and nonatherosclerotic groups in the mild (P < .001), moderate (P < .01), and severe (P < .001) subgroups. The RI values in the atherosclerotic group were much higher than those in the nonatherosclerotic group for the 3 stenotic subgroups. CONCLUSIONS The AT measurement method used widely now cannot differentiate potential differences in pulsus-tardus waveforms between atherosclerotic and nonatherosclerotic RAS; however, it remains a useful approach to detect RAS. Different RI cutoff values should be established according to atherosclerotic and nonatherosclerotic RAS, and consideration of influencing factors for the RI will help reduce misdiagnosis.