Society of Nuclear Medicine Procedure Guideline for Diagnosis of Renovascular Hypertension

Renovascular disease includes renal artery stenosis, renovascular hypertension, and azotemic renovascular disease (ischemic nephropathy). It is important to distinguish between renovascular hypertension and renal artery stenosis. Stenosis of the renal artery is common in nonhypertensive elderly persons and is an associated but noncausative finding in a number of hypertensive patients. Renovascular hypertension is defined as an elevated blood pressure caused by renal hypoperfusion, usually resulting from anatomic stenosis of the renal artery and activation of the renin–angiotensin system. Azotemic renovascular disease refers to renal functional impairment associated with renal atrophy, intrarenal vascular lesions, and interstitial nephritis and fibrosis in the presence of severe atherosclerotic renal artery stenosis. Causes of renovascular hypertension in neonates and infants include renal artery thrombosis after umbilical artery catheterization and coarctation of the aorta. The goal of a screening test for renovascular hypertension in adults is to detect those patients who have renal artery stenosis as the cause of hypertension and to predict curability or amelioration of hypertension after intervention. Renovascular hypertension is estimated to affect fewer than 1%–3% of the unselected hypertensive population and up to 15%–30% of patients referred to a subspecialty center because of refractory hypertension. Clinical features should indicate which patients have moderate or high risk of renovascular hypertension. Clues include abrupt or severe hypertension, hypertension resistant to 3-drug therapy, bruits in the abdomen or flank, unexplained azotemia or recurrent pulmonary edema in an elderly hypertensive patient, or worsening renal function during therapy with angiotensin-converting enzyme inhibitors (ACEIs). ACEI renography is designed to be a test for renovascular hypertension, not for renal artery stenosis. The optimal reference test or “gold standard” in future studies should be the outcome—the response to successful revascularization—not angiographic evidence of renal artery stenosis.