Influence of salt depletion and hydralazine-induced vasodilatation on accuracy of selective renal vein sampling in patients with essential hypertension and renal artery stenosis.

The diagnostic accuracy of renal vein renin (RVR) analyses was evaluated in 63 hypertensive patients treated with sodium depletion and/or hydralazine prior to selective renal vein sampling. A positive RVR study (i.e., lateralization of RVR) was defined as a ratio greater than or equal to 1.5 when RVR from the kidney with renal artery stenosis was compared to RVR from the contralateral kidney. Approximately 40% of patients with essential hypertension had positive RVR studies. Among patients with renal artery stenosis, surgical outcome was correctly predicted in 5 of 8 patients (63%) treated with sodium depletion, whereas outcome was accurately predicted in 11 of 12 patients (92%) treated with hydralazine. These observations demonstrate that a high percentage of patients with essential hypertension have positive RVR studies despite arteriographically normal renal vasculature. Results obtained in patients with renal artery stenosis suggest that stimulation of renin secretion by hydralazine may be of particular advantage prior to renal vein sampling. However, additional data are required to confirm whether activation of specific mechanisms for renin release improves the reliability of the RVR test.