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 dia gnosing renal artery stenosis is the presence of drug-resistant hypert ension. In such patients the prevalence of renal artery stenosis can b e as high as 30%. Atherosclerotic plaques form the major cause of obst ruction of the artery. In young women stenosis often results from fibr omuscular dysplasia. Recently, non-invasive imaging techniques like sp iral CT angiography and magnetic resonance angiography have been propo sed as a substitute for renal arteriography. Their application outside specialized centers needs further evaluation. Doppler ultrasound stud y of the renal arteries is highly operator-dependent and its reliabili ty varies from center to center. Captopril-stimulated peripheral vein renin measurements, captopril-stimulated and unstimulated renal vein r enin measurements, and captopril-enhanced isotope renography are often used to detect renal artery stenosis, or predict the outcome of percu taneous transluminal renal angioplasty (PTRA) or surgery. On the basis of evidence presented so far we consider it good policy to perform is otope renography with either Tc-99m-DTPA or Tc-99m-MAG3, preferably af ter captopril challenge, in all patients who require more than two ant ihypertensive drugs. When such patients show signs of coronary, cerebr al or peripheral vascular disease or renal impairment, we advise renal angiography without prior isotope renography. Peripheral and renal ve in renin measurements generally add little to the diagnostic value of isotope renography. Renal vein renin measurements may be helpful in pa tients with bilateral stenosis. Further studies are needed to confirm that isotope renography after captopril, possibly combined with periph eral or renal vein renin measurements, is a valuable tool for predicti ng 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 th erapeutic success.