Renal autoregulation in medical therapy of renovascular hypertension

Introduction: Renovascular hypertension (RVH) is caused by renal ischaemia associated with haemodynamically significant renal artery stenosis (RAS). The choice of optimal treatment of atherosclerotic RAS is still controversial. Increase in the renal resistive index (RI) value after captopril administration is considered to indicate preserved renal autoregulation. The objective of the study was to assess the effect of medical therapy of RVH on renal autoregulation efficiency in patients with atherosclerotic RAS. Material and methods: 19 persons (38 kidneys) in 2 groups: 1) study: with RVH and stenosis of 1 renal artery 8 patients; 2) control: 11 healthy volunteers. Doppler captopril test with RI measurements and estimation of creatinine clearance (CCr) were performed in both groups at baseline, and after a period of controlled medical therapy (CMT) only in the study group. ABPM was evaluated in controls at baseline, and in the study group at the end of CMT. Results: In the study group the mean period of CMT was 8.3 +/- 2.7 months, the number of antihypertensive drugs was 4.1 +/- 1.0, and mean 24-hour blood pressure was 138/74 mmHg. Mean CCr was stable during the study. Significant increase of RI after captopril was found only in controls. At baseline, in the group of kidneys with a non-stenotic renal artery, significant lowering of RI was observed, and Delta Rl differed significantly from controls. After CMT, Delta RI increased in non-stenotic kidneys in comparison to the baseline, and did not differ from controls. Conclusions: Adequate medical therapy of RVH preserved renal function and improved renal autoregulation efficiency in non-stenotic kidneys.