Renal resistive index and left ventricular hypertrophy in essential hypertension: a close link

The aim of this study was to evaluate renal Doppler resistive index in patients with mild to moderate essential hypertension (EH) and to correlate its changes with the presence of left ventricular hypertrophy assessed by echocardiography. Twenty-eight EH patients (19 males, 9 females, mean age 56.2 +/- 8.6 years) and 13 normotensive subjects (7 males, 6 females, mean age 57.6 +/- 7.9 years) were studied; all patients underwent a complete echocardiographic study (M-mode, two-dimensional and Doppler) and a color Doppler echography of renal and intrarenal arteries. After the renal Doppler waveform was obtained, resistive index was calculated by peak systolic velocity (S) and lowest diastolic velocity (D) with the formula S-D/S. EH patients were divided into two subgroups on the basis of left ventricular mass (LVM): Group EH1 with normal LVM (15 patients) and Group EH2 with increased LVM (13 patients). All patients evidenced normal renal morphology and function and received no therapy throughout the entire observation period. Renal resistive index was significantly higher in EH patients than in controls; however, the maximum difference was observed between normotensive subjects and the EH patients with increased LVM (p < 0.00001). At univariate analysis, significant correlations were found between renal resistive index and age, body mass index, left ventricular relative wall thickness and LVM. However, when multiple regression analysis was used, only age (p < 0.01) and LVM (p < 0.05) remained significant predictors of resistive index. In conclusion, our data show that in EH patients resistive index, which is considered an expression of arterial impedance, is well correlated with the presence of left ventricular hypertrophy, presently considered the best index of the severity of hypertensive disease. This correlation may be the expression of the involvement of two target organs in hypertension.