Assessment of Curable Renovascular Hypertension by Radiographic Technics

Abstract

Aortography is a highly effective means of demonstrating anatomical lesions apt to produce renal hypertension. The hemodynamic significance of renal artery narrowing is difficult to assess angiographically, unless collaterals or a delayed flow of contrast medium can be visualized. Renal artery stenoses of doubtful hemodynamic significance can be evaluated by pressure measurements across the area of narrowing. The principal value of this procedure lies in the exclusion of a pressure gradient, thereby saving the patient from surgical exploration. Demonstration of a pressure gradient indicates hemodynamically significant stenosis, but not necessarily curable renovascular hypertension, since such stenoses may be present in normotensive patients and in those with essential hypertension. The important functional alterations in curable renovas cular hypertension are decreased flow of urine and hyper concentration of modern contrast media. These functional characteristics can best be visualized by intravenous pyelography and forcefully induced diuresis with urea and saline solution. The urea washout test is, in essence, a radiographic Howard test which should be part of routine hypertension pyelography. No longer can the vascular radiologist limit himself to demonstration of the angiographic anatomy. The great goal of modern cardiovascular radiology lies not only in the exact demonstration of vascular anatomy but also in the radiographic assessment of hemodynamics and function.