SYSTEMIC ARTERIAL CHANGES AND PULSE PRESSURE: DIFFERENT IMPACT ON RENAL HAEMODYNAMICS IN HYPERTENSIVE PATIENTS.

Abstract

Objective: Renal resistance index (RRI) is used for kidney disease detection and prognosis, but it also appears a good indicator of systemic vascular changes in hypertensive subjects. Structural atherosclerotic damage, arterial stiffness and pulse pressure may interact each other, and the relationship between intrarenal haemodynamics and systemic vascular alterations has been widely investigated. However, the independent impact of all these parameters on renal haemodynamics and the mechanisms by which they affect renal vasculature remain to be clarified. Design and method: We enrolled 463 hypertensive patients (30–70 years) with normal renal function (group 0; n = 280) and with chronic kidney disease (groups IV; n = 183). All subjects underwent ultrasonographic examination of intrarenal and carotid vasculature, as well as a 24h ambulatory blood pressure monitoring. Results: A statistically significant difference in RRI, carotid intimamedia thickness (cIMT), aortic pulse wave velocity (aPWV) and clinic pulse pressure (PP) was observed in the different 6 groups (all p < 0.001), even after adjustment for age. RRI strongly correlated with cIMT (r = 0.460, p < 0.001), aPWV (r = 0.386, p < 0.001), clinic PP (r = 0.279, p < 0.001) and 24h PP (r = 0.229, p < 0.001) in the entire study population. These correlations were similar in subjects with and without renal dysfunction. In the overall study population, the association between RRI, cIMT and clinic PP remained statistically significant even after adjustment for various confounding factors (figure 1) (respectively b=0.258; p < 0.001; b=0.117; p = 0.006), whereas the relationship between RRI and aPWV was lost in multivariate analysis. Conclusions: cIMT and clinic PP rather than directly aPWV are associated with intrarenal haemodynamics. Our results confirm that RRI may be considered as a renal window of systemic vascular tree, independently of level of renal function.