PRELIMINARY ASSESSMENT OF CAPTOPRIL SONOGRAPHY IN SCREENING FOR RENAL-ARTERY STENOSIS

Rationale and Objectives. We assessed the usefulness of the resistive index (RI) and renal length in predicting a significant renal artery s tenosis (RAS) and evaluated the effect of captopril on the RI in kidne ys with and without a significant RAS. Methods. The RIs and renal leng ths of both kidneys were measured in 39 patients who were referred for captopril renography for suspected renovascular hypertension. The dif ference in RIs (Delta RI), the smaller RI (SRI), the difference in len gths (Delta L), and the shorter length (SL) of the patient's two kidne ys were determined. The accuracy of each of these parameters was calcu lated using captopril renography (n = 39) and arteriography (n = 9) as the gold standards, Results. There was a significant difference in th e Delta RI (p < .05), SRI (p < .001), and Delta L (p < .05) in patient s with a positive captopril renogram for a significant RAS. Captopril increased Delta RI (p = .052) in patients with a positive captopril re nogram (n = 6). Use of an SRI threshold of less than .55 resulted in u ltrasound being as accurate as captopril renography in predicting an a ngio, graphically documented stenosis of greater than or equal to 50%. Conclusion. The RI and renal length are useful in detecting a signifi cant RAS. In this preliminary study, captopril was shown to increase D elta RI in patients with a significant RAS, but larger prospective stu dies are necessary to further assess the value of captopril sonography in detecting a significant RAS.