Renovascular hypertension: Selecting patients for diagnostic angiography and predicting the outcome of therapeutic intervention

A practical indication that a patient needs additional work-up for diagnosing renal artery stenosis is the presence of drug-resistant hypertension. In such patients the prevalence of renal artery stenosis can be as high as 30%. Atherosclerotic plaques form the major cause of obstruction of the artery. In young women stenosis often results from fibromuscular dysplasia. Recently, non-invasive imaging techniques like spiral CT angiography and magnetic resonance angiography have been proposed as a substitute for renal arteriography. Their application outside specialized centers needs further evaluation. Doppler ultrasound study of the renal arteries is highly operator-dependent and its reliability varies from center to center. Captopril-stimulated peripheral vein renin measurements, captopril-stimulated and unstimulated renal vein renin measurements, and captopril-enhanced isotope renography are often used to detect renal artery stenosis, or predict the outcome of percutaneous transluminal renal angioplasty (PTRA) or surgery. On the basis of evidence presented so far we consider it good policy to perform isotope renography with either ^99mTc-DTPA or ^99mTc-MAG3, preferably after captopril challenge, in all patients who require more than two antihypertensive drugs. When such patients show signs of coronary, cerebral or peripheral vascular disease or renal impairment, we advise renal angiography without prior isotope renography. Peripheral and renal vein renin measurements generally add little to the diagnostic value of isotope renography. Renal vein renin measurements may be helpful in patients with bilateral stenosis. Further studies are needed to confirm that isotope renography after captopril, possibly combined with peripheral or renal vein renin measurements, is a valuable tool for predicting the blood pressure response to PTRA or surgery. Besides the results of these diagnostic tests, factors such as age and the progression of atherosclerotic disease are likely to be important determinants of therapeutic success.