Increased renal resistive index in patients with essential hypertension: amarker of target organ damage

Background. Increased renal resistance detected by ultrasound (US) Doppler has been reported in severe essential hypertension (EH) and recently was sh own to correlate with the degree of renal impairment in hypertensive patien ts with chronic renal failure. However, the pathophysiological significance of this finding is still controversial. Methods. In a group of 211 untreated patients with EH, we evaluated renal r esistive index (RT) by US Doppler of interlobar arteries and early signs of target organ damage (TOD). Albuminuria was measured as the albumin to crea tinine ratio (ACR) in three nonconsecutive first morning urine samples. Lef t ventricular mass was evaluated by M-B mode echocardiography, and carotid wall thickness (IMT) by high resolution US scan. Results. RI was positively correlated with age (r= 0.25, P=0.003) and systo lic blood pressure (SBP) (r= 0.2, P=0.02) and with signs of early TOD, name ly ACR (r=0.22, P=0.01) and IMT (r=0.17, P<0.05), and inversely correlated with renal volume (r= -0.22, P=0.01) and diastolic blood pressure (r= -0.23 , P= 0.006). Multiple linear regression analysis demonstrated that age, gen der, ACR and SEP independently influence RI and together account for simila r to 20% of its variations (F=8.153, P<0.0001). When clinical data were ana lysed according to the degree of RI, the patients in the top quartile were found to be older (P<0.05) and with higher SEP (P<0.05) as well as early si gns of TOD, namely increased ACR (P <0.002) and IMT (P< 0.005 by ANOVA), de spite similar body mass index, uric acid, fasting blood glucose, lipid prof ile and duration of hypertension. Furthermore, patients with higher RI show ed a significantly higher prevalence of microalbuminuria (13 vs 12 vs 3 vs 33% chi(2) = 11.72, P=0.008) and left ventricular hypertrophy (40 vs 43 vs 32 vs 60%, chi(2)=9.25, P<0.05). Conclusions. Increased RI is associated with early signs of TOD in EH and c ould be a marker of intrarenal atherosclerosis.