ASSOCIATION OF RENAL RESISTIVE INDEX WITH AORTIC PULSE WAVE VELOCITY IN HYPERTENSIVE PATIENTS.

Abstract

The assessment of renal hemodynamic parameters by duplex Doppler sonography has been used for many years as a diagnostic tool in the daily work-up of kidney diseases. Recent data suggest that these parameters, especially the intrarenal resistive index (RI) may be also associated with systemic vascular changes and with an enhanced cardiovascular risk. However, conflicting data exist in literature about the independent association of aortic stiffness with RI. The aim of this study was to evaluate the relationship between RI and arterial stiffness, assessed by aortic pulse wave velocity (PWV), in the hypertensive subjects consecutively attending our hypertension centre. We enrolled 264 subjects, aged between 30 and 70 years. They were divided into two groups, either with normal renal function (n = 140) or with chronic kidney disease (CKD), ranging from stage 1 to stage 4 of the KDIGO classification (n = 124). The aortic PWV was measured by a computerized oscillometric method (Arteriograph). The GFR was estimated by CKD-EPI equation. A single operator performed duplex Doppler assessment of the renal arteries. Doppler signals were obtained by placing the sample volume along the course of the interlobar arteries. The RI was calculated as the average of six measurements (three from each kidney). Patients with PWV> 12 m/sec showed higher values of RI, both in the overall population (p <0.001) and in the subgroups with (p<0.01) and without CKD (p<0.01). In addition, a statistically significant correlation was observed between aortic PWV and RI in the whole population (r = 0.38, p <0.001) and in the subgroups with (r = 0.35, p <0.001) and without CKD (r = 0:31, p <0.001). These correlations held even after adjustment for several confounding factors. Our results, showing a strong independent association between renal RI and aortic PWV, seem to corroborate the concept that the RI, beyond its prognostic renal value, may be considered as a marker of systemic vascular changes and therefore a predictor of cardiovascular risk.