High altitude sojourn elicits divergent effects in aortic and carotid stiffness in healthy-young adults

Abstract

High altitude exposure challenges the cardiovascular system to compensate for barometric pressure-mediated reductions in arterial oxygen content. Reductions in oxygen content elicit simultaneous increases in sympathetic nervous system activity and vasodilation that may have competing effects on changes in large artery stiffness. The objective of this study was to examine changes in aortic and carotid stiffness during high altitude sojourn in healthy, young adults. We hypothesized that short-term high-altitude sojourn would increase both aortic and carotid stiffness. 17 Generally healthy adults (23±4 yrs, 25.0±3.0 BMI, n=9 females) underwent vascular assessments in the supine position at 1400 m and after an 8-day incremental ascent to 4300 m. Aortic stiffness and carotid β-stiffness were derived from carotid-femoral pulse wave velocity (cfPWV) via applanation tonometry and right common carotid artery ultrasonography, with blood pressure assessed via oscillometry. Ascent from 1400 m to 4300 m resulted in decreased arterial oxygen saturation (-11±4 %, p<0.001) and carotid β-stiffness (-4.48±2.73 au, p<0.001), and increased cfPWV, (+54.98±78.10 cm/s, p=0.01) and mean arterial pressure (+4±7 mmHg, p=0.02). Changes in cfPWV, arterial oxygen saturation, and blood pressure were moderately to strongly correlated (r=-0.425-0.503, p=0.09-0.04). Our data suggest that short term exposure to high altitude has differential effects on carotid versus aortic stiffness despite increases in mean blood pressure. Increases in aortic stiffness appear related to hypoxia-induced reductions in arterial oxygen saturation and concomitant increases in blood pressure, while reductions in carotid stiffness may stem, in-part, from compensatory carotid artery dilation necessary to increase cerebral blood flow at high altitude. Additional research is necessary to further understand mechanisms underlying differential changes in large artery stiffness during high altitude sojourn. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.