Evaluation of intrarenal hemodynamics by Doppler ultrasonography for renoprotective effect of angiotensin receptor blockade

Abstract

It has been shown that both angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II type 1 receptor blockers (ARB) have renoprotective effects via mechanisms that are independent of blood pressure reduction. The aim of this study was to evaluate the intrarenal hemodynamic change with ARB by renal Doppler ultrasonography (RDU) and to assess the mechanism of ARB in patients with hypertension. Thirty hypertensive patients with renal insufficiency caused by glomerular diseases, diabetes and hypertensive nephrosclerosis were included in this study. RDU was performed before and one week after taking ARB. Resistance index (RI) (peak systolic velocity - end diastolic velocity/peak systolic velocity) in the intrarenal segmental artery were calculated, and the amounts of urinary protein or albumin were determined. We defined patients whose microalbuminuria or proteinuria was reduced by greater than 30% by ARB as responders (n = 22) and defined other patients as non-responders (n = 8). There were no significant differences between the responder and non-responder groups in baseline characteristics. RI was significantly improved by ARB in the responder group, but not in the non-responder group. The reduction of RI after ARB treatment was most prominent in patients with hypertensive nephrosclerosis. Improvement in intrarenal hemodynamics might play an important role in the mechanisms of the renoprotective effect of ARB in patients with hypertension.