Hypertension with renal arterial stenosis: humoral, hemodynamic and histopathologic factors

In 46 hypertensive patients with unilateral renal arterial stenosis, peripheral and renal venous plasma renin activity, juxtaglomerular cell count and granularity and systolic pressure gradient across the stenosis were determined. After corrective surgery and a mean postoperative observation period of 4.3 years, 18 patients were completely relieved of hypertension (good responders), 14 had a substantial reduction in arterial pressure (fair responders) and 14 remained hypertensive (poor responders). Analysis of plasma renin activity in both renal veins indicated that a ratio (stenotic/nonstenotic side) greater than 2.0 correctly predicted a favorable surgical result in all cases. Peripheral plasma renin activity was greater than normal in 65 percent of good responders, in 50 percent of fair responders and in one nonresponder. The prognostic accuracy of a pressure gradient greater than 40 mm Hg was 78 percent; no patient with a gradient of less than 40 mm Hg benefited from surgery. An increased juxtaglomerular cell count on the affected side predicted a successful operative result in 88 percent, as did increased granularity in 85 percent of cases. Renal venous renin ratio correlated positively (r =0.738, P less than 0.001) with the pressure gradient across the stenosis. The renal venous plasma renin activity of the affected side also correlated positively (r = 0.771, P less than 0.001) with the absolute count of granular cells in the juxtaglomerular apparatus. Plasma renin activity in both renal veins is the most reliable predictor of operative outcome. The addition of juxtaglomerular cell count or pressure gradient across the stenosis increases prognostic accuracy only slightly. The close mutual correlations between renal venous renin ratio, pressure gradient and juxtaglomerular cell count support the experimental evidence of a causal relation between the hemodynamic effects of the arterial lesion and the humoral and histologic changes observed in hypertension with renal arterial stenosis.