Evaluation by captopril renal scintigraphy and echo-Doppler flowmetry of hypertensive patients at high risk for renal artery stenosis.

Sixty-three hypertensive patients with probability of obstructive renal artery disease underwent both Captopril renal scintigraphy (CRS) and echo-Doppler flowmetry (EDF) before undergoing renal angiography. Angiography revealed renal artery stenosis (RAS) in 42 patients (unilaterally in 26 and bilaterally in 16). The sensitivity and specificity in the identification of RAS > or = 50% were 90% and 94%, respectively for Captopril renography, and 85% and 78% for echo-Doppler flowmetry. Captopril renography correctly identified stenoses greater than 50%, which is usually held to be the limit of hemodynamic significance. While the Doppler examination was more sensitive than Captopril renography (sensitivity 79% versus 64%) in the detection of all degrees of RAS, less information on the functional significance of RAS was provided. Both CRS and EDF could be usefully employed to assess kidney perfusion, but their appropriate clinical use must take into account inherent differences between the two techniques.