Diagnosis and management of renovascular hypertension.

Abstract The clinical history is seldom helpful in establishing a diagnosis of renovascular hypertension. Symptoms are not different from those accompanying hypertension due to other causes, except for the occasional pain associated with a renovascular accident. Generally, the age and sex of patients reveal a much higher incidence of fibromuscular lesions in young women and of atheromatous lesions in older men. In a surgically treated group of 100 patients with apparent renovascular hypertension, 37 gave a family history of significant hypertension. Long duration of the elevation of blood pressure is so common among patients with renovascular hypertension that we have not been able to use recency to distinguish the cause of hypertension. Physical findings may be distinctly helpful in establishing a diagnosis. If hypertension is of one year's known duration, or longer, and parenchymal renal disease and adrenal causes have been excluded, the physician should strongly suspect renovascular hypertension when examination of the optic fundus reveals severe retinal arteriolar narrowing and focal constriction without significant chronic hypertensive sclerosis. A continuous bruit over the lateral upper region of the abdomen virtually confirms the presence of functionally significant severe renal artery stenosis. Systolic-diastolic bruits of high frequency (pitch), long duration and lateral location should also be considered as strongly suggestive of a renovascular lesion even if screening procedures such as urography or isotope renography reveal no significant differences of renal size or function. The combination of isotope renography and excretory urography can produce comparative estimates of mass and function of the separate kidneys. Neither procedure alone will permit a diagnosis of renal artery stenosis, and therefore the results of each should be considered as normal or abnormal rather than as positive or negative. Severe unilateral renal artery stenosis, or stenosis more severe on one side than the other, is commonly associated with a smaller renal size and renographic abnormality on that side; but these procedures may indicate that the kidneys are of equal size and have equal function even though the patient has surgically remediable hypertension. Despite improvement in screening procedures, renal artery stenosis can be diagnosed only by renal arteriography. The significance of these lesions should be confirmed by differential renal function studies or renal venous renin activity determination, or both, before surgical management is undertaken. The severity of stenosis is a deciding factor both in establishing the diagnosis and in determining the treatment. Hypertension caused by slight or moderate stenosis commonly responds favorably to medical management. We consider operation in such cases only if control of blood pressure by medical means proves unsatisfactory or if deterioration of renal function is demonstrated by clearances of inulin and paraaminohippurate. The location and type of stenosing lesions dictate the choice of operative technic. Atheromatous stenosis occurs far more commonly in the aorta and proximal portion of the renal artery than in the main artery, and rarely is located in the primary branches; hence endarterectomy, plastic repair, or bypass procedures usually are feasible. Fibromuscular dysplasia occurs almost exclusively in the distal three fourths of the main renal artery or its primary branches. Many of these distal lesions are not suited to surgical correction. However, when the morphologic and functional characteristics of the renovascular lesions are carefully analyzed preoperatively, and when technics and surgical therapy are appropriate to the problem at hand, atheromatous and fibromuscular stenosis can often be successfully repaired or bypassed. Nephrectomy (partial or total) may be necessary, however, for atheromatous lesions (because of severe ischemic atrophy with interstitial fibrosis or renal infarction) or fibromuscular lesions (because of involvement of the branch arteries or renal infarction). Our experience with the frequent necessity of nephrectomy when lesions of the branch arteries are demonstrated arteriographically in patients with fibromuscular dysplasia has often caused us to undertake medical antihypertensive therapy, at least on a trial basis, and reconsider operation subsequently if control of blood pressure is unsatisfactory or if renal function deteriorates.