Veglio F, Frascisco M, Melchio R, Provera E, Rabbia F, Oliva S, Chiandussi L
Assessment of renal resistance index after captopril test by Doppler in essential and renovascular hypertension

Kidney Int (Nov) 48:1611-1616 1995

The optimal test to screen for renovascular hypertension is unclear. Ultrasonic duplex scanning can detect renal artery stenosis (RAS); however, its utility in demonstrating functional significance of stenotic lesions has not previously been studied. 22 patients with renovascular hypertension (unilateral RAS on angiography with positive captopril test and abnormal captopril scintigraphy), 45 essential hypertensives, and 15 normotensives had Doppler parameter resistance indices (RI) measured before and after 50 mg captopril. The RI (quantitation of arterial impedance) was measured at the hilum and in at least three interlobar arteries. RI was calculated using the following formula: (peak systolic frequency shift - lowest diastolic frequency shift)/peak systolic frequency shift. The RI decreased more after captopril in renovascular vs. essential hypertensive patients. Sensitivity and specificity of this method for detection of unilateral RAS were 93 and 91%, respectively. Duplex Doppler appears to be a good screening test for renovascular hypertension in centers experienced with this procedure. (Leehey)

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H: Special problems : Renovascular hypertension