Orthostatic Blood Pressure Changes and Subclinical Markers of Atherosclerosis

Abstract

Background: Using a simple standing-up test in normotensive subjects, we evaluated orthostatic upright postural blood pressure (BP) changes and autonomic nervous function, as well as the relationship between orthostatic BP changes and subclinical markers of atherosclerosis.

Methods: A total of 515 normotensive subjects aged 35-75 years (58.4±10.0 years) were enrolled. We measured body mass index (BMI), systolic BP (SBP) and diastolic BP (DBP), serum lipids, hemoglobin A1c (HbA1c), high-sensitivity C-reactive protein (hs-CRP), and urinary albumin-to-creatinine ratio. Brachial to ankle pulse wave velocity (baPWV) and carotid mean intima-media thickness (IMT) were measured. Participants underwent a simple standing-up test involving sitting then standing for 2 minutes each, followed again by sitting. To evaluate autonomic fluctuations, we calculated the coefficient of variation of the R-R interval, the ratio of low to high frequency heart rate variability (LF/HF), and the coefficient of component variance of high frequency.

Results: SBP and DBP decreased when standing, with a reduction of SBP when changing position of -8.0±10.2mm Hg. Orthostatic hypotension (OH) produced a significantly higher SBP than without OH. The baPWV was significantly higher in OH than in without OH. Stepwise regression analysis adjusted for age, sex, BMI, baseline SBP, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting glucose, HbA1c, hs-CRP, IMT, late systolic peak of the pressure wave form (SBP2), and baPWV confirmed that baPWV, SBP2, and triglycerides were independently related to orthostatic BP changes. Multiple regression analyses showed that a decrease in SBP as well as baseline SBP, age, BMI, and fasting glucose were independent determinants of PWV.

Conclusions: We have shown that increased arterial stiffness was associated with OH during a standing-up test. Arterial stiffness may contribute to greater BP responses to postural changes from standing.

Keywords: arterial stiffness; arterial wave reflection; blood pressure; hypertension; orthostatic hypotension..