[Use of intravenous nicardipine for the diagnosis of renovascular hypertension]

Abstract

The diagnosis of remediable renovascular hypertension (RVH) requires demonstration of lateralization of renal vein renin (RVR). In order to increase the accuracy of RVR ratio, we investigated the acute effects of a bolus of Nicardipine (Nic.: 4 mg i.v.) on hemodynamics and RVR in 19 patients. 13 patients had an unilateral renal artery stenosis greater than 75% (RVH: 10 atheroma and 3 fibrodysplasia) and 6 patients had essential hypertension (EH). In 6 patients (5 RVH and 1 EH) treatment could not be discontinued and only a monotherapy by central alpha-agonists was prescribed. RVR samples were obtained 15 minutes after renal vein catheterization (baseline values: T0) and 10 minutes after Nic. injection (T10). During the whole procedure, mean blood pressure (MBP) and heart rate (HR) were monitored every 2 minutes by an automatic device. Active renin was measured by a new immunoradiometric assay. A RVR ratio (stenotic/contralateral side) greater than 1.5 was considered as a positive ischemic index.

Results: The relative changes in MBP and HR between T0 and T10 were of same magnitude in both groups. No patient suffered any untoward effect from the fall in MBP. Nic. increased RVR release from both sides in RVH group as well as in the EH group. At baseline, 6/13 of the RVH patients and none of the EH patients had a RVR greater than 1.5. After Nic. injection, all the RVH patients had a RVR greater than 1.5 and none among EH patients. We conclude that single i.v. Nic. bolus is a safe and a reliable procedure which increases diagnostic accuracy by enhancing RVR when there is an unilateral RVH disease.