Does sodium intake affect the relationship between blood pressure and vascular damage?

INTRODUCTION Although the differences between central and peripheral blood pressure (BP) values have been known for decades, the consequences of decision making based on peripheral rather than central BP have only recently been recognized. Recently, a U-shaped relation between sodium intake and cardiovascular risk has been suggested.

OBJECTIVES The aim of the study was to evaluate the relationship between intima-media thickness (IMT) and central and peripheral BP as well as the effect of 24-hour urinary sodium excretion on this relationship. 

PATIENTS AND METHODS The study included 182 subjects (mean age, 37.3 ±14.0 years, 92 men and 90 women) who were members of families randomly selected from one of the gminas (administrative regions) in southern Poland. In all patients, peripheral and central BP (using applanation tonometry), IMT, and 24-hour sodium excretion were measured. 

RESULTS Hypertension was observed in 44.5% of the participants. The mean urinary sodium excretion was 243 ±81 mmol/d. IMT was significantly more correlated with central pulse pressure (PP) compared with peripheral PP (r = 0.54 vs r = 0.27; P <0.01). After multivariate adjustments, IMT remained significantly related to central systolic BP and central and peripheral PP. When the study group was divided according to the tertiles of sodium excretion, central PP was related to IMT only in the second and third tertiles. When the study group was divided according to sex and sex-specific median values of sodium excretion, IMT was associated with central PP only in subjects with sodium excretion exceeding the median values (both in men and women).

CONCLUSIONS IMT is more correlated with central than with peripheral BP. The association between IMT and central PP may be modulated by sodium intake. This hypothesis should be tested in larger studies.