Evaluation of patients with renovascular hypertension.

R ENOVASCULAR hypertension is the most prevalent form of surgically curable high blood pressure. Nevertheless, controversy surrounds the screening of patients and the choice of appropriate diagnostic workup. In testing for renovascular hypertension, differences of opinion can be anticipated in view of several dilemmas. First, renovascular hypertension is a retrospective diagnosis. A technically acceptable renal arteriogram can establish the diagnosis and usually the etiology of renal artery stenosis. Whether the stenotic lesion is responsible for all or part of the elevated blood pressure is determined retrospectively by the blood pressure response to corrective surgery or to transluminal angioplasty (PTA). Other diagnostic tests are not specific for renal artery stenosis. Rather, they merely indicate nonspecific phenomena, such as turbulent blood flow in a large intraabdominal artery (abdominal bruit), disparity of kidney or endocrine function between the two kidneys (radionuclide studies, intravenous urogram, renal vein renins), or angiotensin-mediated hypertension (saralasin test). Each of these tests may be positive in disorders other than renovascular disease and has significant rates of false negativity. Thus, no test or combination of tests can reliably diagnose renovascular hypertension. Second, renovascular hypertension is a "rare" disorder. Depending upon referral sources, estimates of the prevalence of renovascular hypertension range from 0.2% to 10% of the hypertensive population. This low prevalence compared to essential hypertension skews cost and risk benefits of the tests for its diagnosis. Because of the low prevalence of renovascular hypertension, even a given diagnostic test of high sensitivity and specificity will have a low predictive value and will result in a large number of patients with essential hypertension being subjected to unnecessary procedures. Third, renovascular hypertension responds to antihypertensive drug therapy. No prospective, randomized trials of medical vs operative therapy of renovascular hypertension have been published. Nevertheless, recent reports suggest that the elevated blood pressure can be controlled, particularly with the use of betablockers or captopril. 2