Noninvasive diagnosis of renal artery stenosis by ultrasonic duplex scanning

We retrospectively studied the results of duplex scanning for evaluation of renal artery disease in 158 patients. Satisfactory examinations were achieved in 144 patients (90%). Arteriograms were available for 43 renal arteries. We used the ratio of the peak velocities in the renal artery and the aorta (RAR) to separate nonstenotic arteries (less than 60% diameter reduction) from stenotic arteries (greater than 60% diameter reduction). With an RAR of greater than 3.5 to indicate stenotic lesions, duplex scanning had a sensitivity of 91% (20 of 22 diseased arteries correctly identified) and specificity of 95% (20 of 21 normal or insignificantly diseased arteries correctly identified). One of four occluded arteries was incorrectly interpreted as patent because of misidentification of a collateral vessel. Prospective studies will be necessary to validate this test and establish other criteria for a more detailed classification of renal artery stenosis. The ratio of the end-diastolic to peak systolic velocities in the renal artery (EDR) tended to decrease with increasing serum creatinine levels, presumably because renal vascular resistance increases with end-stage parenchymal disease. EDR may prove useful in the detection of advanced parenchymal disease before renal artery revascularization is attempted.