Renovascular hypertension
Renovascular hypertension occurs when systemic blood pressure rises because of stenosis of the major renal arteries or their branches or because of intrarenal atherosclerosis. This narrowing (sclerosis) may be partial or complete, and the resulting blood pressure elevation may be benign or malignant. About 5% to 15% of patients with high blood pressure display renovascular hypertension.
Causes
In about 95% of patients, renovascular hypertension results from either atherosclerosis (especially in older males) or fibromuscular diseases of the renal artery wall layers (for example, medial fibroplasia and, less commonly, intimal and subadventitial fibroplasia). Other causes include arteritis, anomalies of the renal arteries, embolism, trauma, tumor, and dissecting aneurysm.
Stenosis or a renal artery occlusion stimulates the affected kidney to release renin, an enzyme that converts angiotensinogen (a plasma protein) to angiotensin I. As angiotensin I circulates through the lungs and liver, it converts to angiotensin II, which causes peripheral vasoconstriction, increased arterial pressure and aldosterone secretion and, eventually, hypertension.
Complications
Renovascular hypertension can lead to such significant complications as heart failure, myocardial infarction (MI), loss of vision, cerebrovascular accident and, occasionally, renal failure.
Assessment
In the early stages, the patient may complain of flank pain. During your assessment, you may note reduced urine output, elevated blood pressure, and a systolic bruit over the epigastric vein in the upper abdomen on auscultation.
As the disorder progresses, the patient may report headache, nausea, anorexia, fatigue, palpitations, tachycardia, and anxiety. If renal failure occurs, you may notice alterations in the patient’s level of consciousness and pitting edema. Auscultation may reveal bibasilar crackles.
Diagnostic tests
An isotopic renal blood flow scan and rapid-sequence excretory urography are needed to identify renal blood flow abnormalities and discrepancies of kidney size and shape. Renal arteriography reveals the actual arterial stenosis or obstruction.
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