The associations among vascular function, baroreceptor sensitivity, and their changes in hypertension

Abstract

Backgrounds: Abnormal vascular function assessed by Pulse Wave Velocity (PWV), pressure wave analysis, and/or Flow-Mediated vasodilatation (FMD) and abnormality of Baroreceptor Sensitivity (BRS) are noted as a risk for cardiovascular disease independent of conventional risk factors. However, their relationships have not been fully clarified. Objective: The present study was conducted to examine the association among vascular function, BRS, and their longitudinal changes. Methods: In 329 patients with hypertension (60±10 years old) (269 were under anti-hypertensive medication and 61 were without medication), brachial-ankle PWV (baPWV), radial Augmentation Index (rAI), the second peak of radial pressure wave form (SP2); a marker of central systolic pressure, FMD, and BRS were measured. As longitudinal assessments, in 216 patients under anti-hypertensive medication, these parameters were repeatedly at 2 years' interval, and in 61 patients without medication, they were also repeatedly measured 1 year after the start of anti-hypertensive medication. Results: In a cross-sectional assessment (n=329), BRS had a significant relationship with baPWV (r= -0.202, p<0.001), but not with rAI, SP2, FMD, and also systolic and diastolic blood pressure. This relationship was significant after adjustment of age. In longitudinal assessments, the change of BRS during the 2 years' follow-up period had a significant relationship with the change of baPWV (r=-0.386, p<0.001), but not with that of rAI, SP2, and FMD. In 61 patients who were started anti-hypertensive medication, BRS (from 7.1±3.7 msec/mmHg to 9.4±4.4 msec/mmHg, p<0.001), baPWV (from 17.2±2.6 to 14.8±1.8 m/sec, p<0.001), SP2, and FMD were significantly improved after the start of 1 year's anti-hypertensive medication. Then, the change of BRS before and after the anti-hypertensive medication had a significant relationship with that change of baPWV (r=-0.254, p<0.001). Conclusions: Increased stiffness in large to middle-sized arteries, rather than abnormal central hemodynamics or endothelial dysfunction, may have significant association with the abnormality in neural regulation of blood pressure in patients with hypertension. These abnormalities might be improved by anti-hypertensive treatment.