Left ventricular function, vascular pulsatility and renal microcirculation in essential hypertension

Purpose: Recent studies indicate that ultrasound derived renal resistive index (RI) is not only an accurate index of intrarenal hemodynamics, but may reflect systemic circulation performance. Aim of our study was to explore the relationship between left ventricular function and RI in essential hypertensive (EH) patients. Methods: We studied 409 consecutive, newly diagnosed, never treated EH patients (mean age 51±13 year, 52% male). Evaluation of left ventricular diastolic function was assessed by echocardiography, including transmitral conventional and tissue Doppler imaging, from six basal segments of the left ventricle. Stroke volume was calculated multiplying LVOT velocity time integral with cross sectional area and normalized by body surface area (SVI). Moreover, all patients underwent renal Doppler ultrasound with RI measurement. The mean value of RI from both kidneys was used for this analysis. Results: The mean±SD value of RI was 0.62±0.07, higher in females than males (0.64±0.06 vs. 0.60±0.06, p<0.001). Table presents significant correlations between RI, demographic variables and indices of left ventricular function. In both genders, diastolic function deterioration and increases in stroke volume were associated with increased RI. Multivariable regression analysis revealed that independent predictors of RI were gender (b=-0.04, p<0.001), 24hr heart rate (b=-0.001, p<0.001), 24hr pulse pressure (b=0.002, p<0.001), transmitral E/A ratio (b=-0.02, p=0.048), TDI mean Em/Am ratio (b=-0.034, p<0.001) and SVI (b=0.001, p=0.008). Correlations of renal resistive index Conclusion: In middle-aged never treated EH patients, left ventricular diastolic dysfunction and vascular pulsatility represents strong modifiers of renal microcirculation resistance.