Relationship Between 24-Hours Urinary Sodium Excretion and Arterial Stiffness in Controlled Hypertensive and Resistant Hypertensive Individuals

Abstract

Objective: To compare the influence of dietary sodium intake through 24-hours urinary sodium excretion (Na + Ur24 h) on arterial stiffness markers in controlled and resistant hypertensive individuals. Design and method: 126 patients were randomized in an observational and cross-sectional study, divided into two groups: 63 in the controlled hypertension group (CHTN) and 63 in the resistant hypertension group (RHTN). All were submitted to clinical evaluation, laboratory tests, Na + Ur24 h and non-invasive central hemodynamic evaluation by the SphygmoCor® and Mobil-O-Graph® system to determine arterial stiffness parameters. Results: Clinical characteristics and laboratory tests were similar in both groups. There was no statistical significance between CHTN and RHTN for Na + Ur24 h values (186.60 ± 92.15 vs.179.76 ± 66.91 mEq/L, respectively). The carotid-femoral pulse wave velocity (cfPWVc) showed no statistically significant difference between CHTN and RHTN (10.52 ± 2.47 m/s vs. 10.21 ± 2.27 m/s, respectively). Central hemodynamic parameters were statistically different between the groups assessed by 24-hour ambulatory blood pressure monitoring (ABPM - Mobil-O-Graph®). RHTN group had higher cardiac output during sleep and greater vascular resistance during wakefulness and 24 hours than CHTN group (p < 0.05) in ABPM. Conclusions: Na + Ur24 h excretion is similar between groups, but there is better adherence to dietary sodium intake restriction in the resistant hypertension group. Physiological hemodynamic parameters are altered in the RHTN group, such as cardiac output and peripheral vascular resistance, a fact that evidences their participation in the pathophysiological process of resistant hypertension.