Does arterial stiffness affect orthostatic hypotension among high-altitude Tibetans?

Association between arterial stiffness and orthostatic hypotension: A systematic review and meta-analysis

Background: Orthostatic hypotension, defined as a decrease in blood pressure on standing, is associated with an increased risk of mortality and cardiovascular events in the general population. In addition, it has recently been suggested that arterial stiffness is independently associated with orthostatic hypotension, which may be due to a loss of the buffering effect of the ascending aorta and an early return of pressure waves. However, the specific mechanisms underlying this association remain unclear. Thus, we aimed to evaluate the association between orthostatic hypotension and arterial stiffness in the adult population. Methods: PubMed, Scopus, Web of Science, and Cochrane Library databases were searched from inception to 31 January 2022. The DerSimonian and Laird method was used to calculate pooled odds ratio (OR) estimates and their respective 95% confidence intervals (95% CI) for the association between orthostatic hypotension and arterial stiffness. Results: Overall, 11 studies were included, with a total of 10,611 subjects. Our results showed that increased arterial stiffness raises the risk of orthostatic hypotension (OR: 1.40, 95% CI: 1.28-1.54), with a stronger association at central arterial stiffness (OR: 1.50, 95% CI: 1.34-1.68) than at peripheral arterial stiffness (OR: 1.29, 95% CI: 1.17-1.43). Conclusion: Our findings showed that increased arterial stiffness raises the risk of orthostatic hypotension by 40% among the adult population. Considering that orthostatic hypotension, which is usually a consequence of antihypertensive treatment, has been widely associated with the risk of cardiovascular events, appropriate control of arterial stiffness could be a clinical strategy to prevent cardiovascular morbidity and mortality.

Relationship between lipid parameters and vascular mechanical characteristics among a normotensive population without diabetes mellitus residing at the Qinghai-Tibet plateau: a cross-sectional study

Background

There is limited evidence regarding the relationship between lipid parameters and vascular mechanical characteristics in the normotensive population without diabetes mellitus. The aim of this study was to identify an association between lipid parameters and changes in vascular mechanical characteristics between men and women, and in women before and after menopause.

Methods

Six hundred-seventy patients who underwent vascular functional testing and who fulfilled the inclusion and exclusion criteria were enrolled in our cross-sectional study. All participants were from the Qinghai–Tibet Plateau (Luhuo County, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, China; mean altitude: 3860 m). Trained clinical physicians assessed brachial-ankle pulse wave velocity (Ba-PWV) and augmentation index adjusted to a 75-beats-per-minute heart rate (AIx@75). To investigate the relationship between lipid parameters and vascular mechanical characteristics in different sexes and menstrual stages, partial correlation analysis and multiple linear regression were used.

Results

The 670 participants comprised 445 women (103 post-menopausal). Mean Ba-PWV and AIx@75 were 1315.56 ± 243.41 cm/s and 25.07% ± 15.84%, respectively. Men had greater Ba-PWV values compared with women (1341.61 ± 244.28 vs 1302.39 ± 242.17 cm/s, respectively; P < 0.05), while AIx@75 values were higher in women compared with men (27.83% ± 15.85% vs 19.64% ± 14.40%, respectively; p < 0.001). In the partial correlation analysis adjusted for age, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and non-high-density lipoprotein cholesterol (HDL-C) were associated with Ba-PWV in both men and women (p < 0.05); however, the magnitude was larger in men. Statistical significance was not seen for AIx@75 among both men and women. Multiple linear regression analysis revealed that TC (β = 0.165, p = 0.024) and non-HDL-C (β = 0.151, p = 0.042) remained independent predictors of change in Ba-PWV in men after adjusting for age, mean arterial pressure, waist circumference, hemoglobin, platelet count, fasting blood glucose, estimated glomerular filtration rate, and uric acid. After adjusting for traditional cardiovascular risk factors, pre-menopausal women had a similar association to that of men between LDL-C (β = 0.126, p = 0.030), non-HDL-C (β = 0.144, p = 0.013), TC/HDL-C (β = 0.162, p = 0.005), LDL-C/HDL-C (β = 0.142, p = 0.013) and Ba-PWV; however, post-menopausal women had no association between the lipid parameters and vascular function.

Conclusions

Overall, TC and non-HDL-C were independent associated factors for vascular compliance alterations evaluated through Ba-PWV in normotensive men. In pre-menopausal women, LDL-C, non-HDL-C, TC/HDL-C and LDL-C/HDL-C were independent associated factors for vascular compliance alterations. After controlling for traditional risk factors, lipid profiles were not associated with these metrics for AIx@75, which can measure the amplification of reflex flow, because of the high number of confounding factors that do not genuinely reflect changes in vascular characteristics. Lipid factors did not appear to be linked to vascular function in post-menopausal women.

Mechanisms and Molecular Targets of Compound Danshen Dropping Pill for Heart Disease Caused by High Altitude Based on Network Pharmacology and Molecular Docking

Compound Danshen dropping pill (CDDP), a famous Chinese medicine formula, has been widely used to treat high-altitude heart disease in China. However, its molecular mechanisms, potential targets, and bioactive ingredients remain elusive. In this study, network pharmacology, molecular docking, and validation experiments were combined to investigate the effective active ingredients and molecular mechanisms of CDDP in the treatment of high-altitude heart disease. Tan IIA may be the main active component of CDDP in the treatment of high-altitude heart disease via HIF-1/PI3K/Akt pathways.