Pattern recognition of loss of early systolic peak by Doppler ultrasound has a low sensitivity for the detection of renal artery stenosis.

In a group of 57 hypertensive patients seen in the out-patient department, the authors did a prospective study to the value of pattern recognition of changes in early systolic peak by Doppler ultrasound (DU) in the examination of renal arteries, as compared with intra-arterial digital subtraction angiography. In five patients (8.7%) DU resulted in technical failure, in one because of the inability to hold breath long enough, in one because the Doppler signals from one part of the kidney were unclear and in three because overlying adipose tissue hindered the examination. Among the remaining 52 patients, 13 had unilateral and six bilateral stenoses greater than 50% of the luminal surface on angiography. By DU 10 patients with a stenosis were identified, one of which was a false positive result. Of the remaining nine, six patients had a unilateral stenosis and three a bilateral stenosis that was identified as unilateral by ultrasound. Therefore, none of the bilateral stenosis was identified as such by DU. Thus, for the detection of renal artery stenoses greater than 50% visual waveform analysis of DU signals has a sensitivity of 47% and a specificity of 97%. The conclusion is therefore that the DU procedure employed in this study has a limited value in the examination of the renal arteries of hypertensive patients with the aim to detect renal arterial stenosis.