Intrarenal and carotid hemodynamics in patients with essential hypertension

BACKGROUND: The pulsatility index (PI) and resistive index (RI) are used as markers of peripheral vascular resistance. Recently intrarenal PI and RI were introduced for the evaluation of the severity of acute and chronic renal failure, as well as for the diagnosis of renal artery stenosis and kidney graft rejection. In the present study, we evaluated intrarenal PI and RI in patients with essential hypertension. METHODS: Fifty-one patients with essential hypertension participated. The intima-media thickness (IMT) and mean diastolic (Vd) and systolic velocity (Vs) in the common carotid artery (CCA) were measured using ultrasound and Doppler flow methods. Relative diastolic flow velocity (Vd/Vs) was calculated as an assessment of CCA hemodynamics. Renal Doppler flow was obtained from the interlobar arteries in each of two kidneys. The mean PI ([peak systolic velocity--end-diastolic velocity]/mean velocity) and mean RI ([peak systolic velocity--end-diastolic velocity]/peak systolic velocity) were calculated. RESULTS: Intrarenal PI and RI were positively correlated with IMT and negatively correlated with Vd/Vs in CCA, indicating that renal vascular resistance is related to carotid stiffness. A stepwise regression analysis revealed that age and pulse pressure were independently associated with intrarenal PI and RI. CONCLUSIONS: These results suggest that the measurement of PI and RI is useful for the evaluation of arterial stiffness in patients with essential hypertension.