Renovascular Hypertension
Approximately 5% to 10% of patients with hypertension have a curable etiology of which renovascular disease is the most common. It is important to identify this small group because these are often the most difficult hypertensive patients to manage medically and because their renal lesions are usually progressive and can lead to significant renal damage.
MECHANISMS OF RENOVASCULAR HYPERTENSION
The preponderance of experimental data suggests that the mechanism of hypertension in renovascular disease is produced by stimulation of the renin-angiotensin system.
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Only renal artery stenosis of a critical degree (>70%) will result in a functionally significant reduction in renal blood flow, thereby stimulating increased renin secretion. Hypertension results from the direct vasoconstrictor effect of angiotensin II and the increased vascular volume secondary to sodium retention by aldosterone.
PATHOLOGY
The major pathologic lesions producing renal artery narrowing are atherosclerosis (70%) and fibromuscular disease (30%).
Atherosclerosis
Atherosclerotic lesions cause most cases of renovascular hypertension (RVH) and usually involve the orifice and proximal 2 cm of the renal artery (i.e., near the aorta). Manifestations of generalized atherosclerosis involving the abdominal aorta and coronary, cerebral, and peripheral vasculature are usually evident.
Medial Fibroplasia
Medial fibroplasia is the second most common cause of RVH. It occurs characteristically in females aged 20 to 50 years and produces a typical multifocal “string of beads” pattern on angiography that starts in the midrenal artery and often extends into peripheral branches. Hemorrhage and dissection are rare. Correction is indicated in younger individuals.
Perimedial Fibroplasia
Perimedial fibroplasia is a progressive fibrous disease of young females that occurs only in the renal artery. It results in an irregular, severely stenotic lesion that often appears beaded on angiography. Surgical correction is indicated.
Intimal Fibroplasia
Intimal fibroplasia is a progressive disease that generally occurs in children or young adults, involves the proximal or midportion of the artery, and often dissects. These lesions should be surgically corrected.
WORKUP
History
Disease onset before age 30 and a negative family history for hypertension should suggest a renovascular etiology. A history of severe
hypertension, headaches, or difficult medical management is also common. Patients may give a history of angina, congestive heart failure, cerebrovascular accidents, or intermittent claudication.
hypertension, headaches, or difficult medical management is also common. Patients may give a history of angina, congestive heart failure, cerebrovascular accidents, or intermittent claudication.
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