Renovascular Hypertension Hypertensive Encephalopathy Renovascular Hypertension Acute or chronic elevation of systemic BP caused by partial or complete occlusion of one or more renal arteries or their branches, often correctable by surgery or percutaneous transluminal angioplasty. Stenosis or occlusion of one or both main renal arteries or their branches or an accessory renal artery or its branches can cause hypertension by inciting release of the enzyme renin from juxtaglomerular cells of the affected kidney. Rarer causes of renal arterial stenosis or obstruction include emboli, trauma, inadvertent ligation during surgery, and extrinsic compression of the renal pedicle by tumors. Rapid progression to malignant hypertension within 6 mo of onset suggests renal artery disease. Trauma to the back or flank, or acute pain in this region with or without hematuria, should alert the physician to the possibility of renovascular hypertension, but these historic features are rare.
Renovascular hypertension is characterized by high cardiac output and high peripheral resistance.
The main justification for diagnostic evaluation is to find a surgically curable lesion. No available test is ideal. Delayed perfusion or decreased function of one kidney on the 99 Tc-DTPA scintiscan suggests ischemia. The sensitivity and specificity can be enhanced by comparing scans done before and after the oral administration of captopril. Measurements of renal vein renin activity are not often necessary and are sometimes misleading in diagnosing renovascular hypertension.