IMPACT OF DIETARY-SODIUM INTAKE ON LEFT-VENTRICULAR DIASTOLIC FILLINGIN EARLY ESSENTIAL-HYPERTENSION

Aims Dietary sodium intake modulates left ventricular hypertrophy in e stablished essential hypertension independent of blood pressure level. We conducted this study to elucidate the relationship between sodium intake and left ventricular structural or functional changes in early essential hypertension. Methods Forty-four young male patients (age 25 .9 +/- 2.6 years) with mild essential hypertension that had never been treated and 45 normotensive male control subjects of similar age were examined. Dietary sodium intake was measured from 24 h urinary sodium excretion, blood pressure from 24 h ambulatory monitoring (SpaceLabs 90207), left ventricular structure from 2-D guided M-mode echocardiogr aphy, and diastolic filling of the left ventricle las the main compoun d of diastolic function in a young population) by pulse-wave Doppler s onography.Results In hypertensive patients, daily sodium excretion cor related with the ratio of late (A) to early (E) maximum velocity (Vmax A/E; r= +0.27, P=0.07), velocity time integrals (A/E; r=+054, P<0.001 ) as well as atrial contribution, as a percent of left ventricular fil ling (VH ATCO; r= +0.52, P<0.001) independent of heart rate, whereas t he opposite correlations were observed in normotensives (all P<0.001). Stepwise multiple regression analysis confirmed these results. Sodium excretion emerged as the strongest independent determinant of impaire d diastolic filling in hypertensive patients (velocity time integrals A/E: R-2=0.49, beta=+0.57, P=0.0001; VH ATCO: R-2=0.48, beta=+0.56, P< 0.0001; Vmax A/E: ns). In normotensive subjects, sodium excretion was a similar strong, but inverse determinant of diastolic filling (veloci ty time integrals A/E: R-2=0.40, beta=-0.43, P=0.0028). Heart rate was a strong determinant of diastolic filling in hypertensive patients (b eta=+0.55, P=0.0002) and in normotensive subjects (beta=+0.34, P=0.011 ). Left ventricular mass and end-diastolic volume index were not relat ed to diastolic filling in either group. Conclusion In early essential hypertension, sodium excretion is correlated with impaired left ventr icular diastolic filling independent of left ventricular mass. The ren in-angiotensin-aldosterone system might be a mediator of the observed correlation.