Impact of blood pressure perturbations on arterial stiffness.

Although the associations between chronic levels of arterial stiffness and blood pressure (BP) have been fairly well studied, it is not clear whether and how much arterial stiffness is influenced by acute perturbations in BP. The primary aim of this study was to determine magnitudes of BP dependence of various measures of arterial stiffness during acute BP perturbation maneuvers. Fifty apparently healthy subjects, including 25 young (20-40 yr) and 25 older adults (60-80 yr), were studied. A variety of BP perturbations, including head-up tilt, head-down tilt, mental stress, isometric handgrip exercise, and cold pressor test, were used to encompass BP changes induced by physical, mental, and/or mechanical stimuli. When each index of arterial stiffness was plotted with mean BP, all arterial stiffness indices, including cardio-ankle vascular index or CAVI (r = 0.50), carotid-femoral pulse wave velocity or cfPWV (r = 0.51), brachial-ankle pulse wave velocity or baPWV (r = 0.61), arterial compliance (r = -0.42), elastic modulus (r = 0.52), arterial distensibility (r = -0.32), ß-stiffness index (r = 0.19), and Young's modulus (r = 0.35) were related to mean BP (all P < 0.01). Changes in CAVI, cfPWV, baPWV, and elastic modulus were significantly associated with changes in mean BP in the pooled conditions, while changes in arterial compliance, arterial distensibility, ß-stiffness index, and Young's modulus were not. In conclusion, this study demonstrated that BP changes in response to various forms of pressor stimuli were associated with the corresponding changes in arterial stiffness indices and that the strengths of associations with BP varied widely depending on what arterial stiffness indices were examined.

Interrelationships Among Various Measures of Central Artery Stiffness.

BACKGROUND: A number of different techniques and methodologies have been applied to quantify stiffness of arteries. Because measures of arterial stiffness differ in regards to measurement locations as well as properties, it is not clear how well these measures that are supposed to reflect the same arterial wall properties are related. METHODS: Interrelationships between different measures of arterial stiffness were evaluated in 50 apparently healthy subjects varying in age. RESULTS: Significant relations ranging from mild to strong were observed among measures of arterial stiffness while some measures were not significantly associated. Cardio-ankle vascular index (CAVI) was significantly associated with carotid-femoral pulse wave velocity (cfPWV) and brachial-ankle pulse wave velocity (baPWV). Ultrasound-derived measures of arterial stiffness (e.g., compliance, distensibility) were weakly or not significantly related to pulse wave velocity (PWV) measures. The limits of agreement between each of arterial stiffness measures based on the Bland-Altman analyses indicate that there were close agreements (CI = 1.12-1.52) between CAVI, cfPWV, and baPWV. However, agreements between PWV measures and ultrasound-derived measures were mild to moderate. ß-stiffness index demonstrated large 95% CIs with other measures. When associations between relative changes in various measures of arterial stiffness in response to isometric handgrip exercise were evaluated, the general trend of associations was similar to the relations observed at rest. ß-stiffness index was not related to most measures of arterial stiffness. CONCLUSION: These results suggest that the techniques used to assess arterial stiffness may not be interchangeable in clinical and research settings and that comparisons of findings obtained with different arterial stiffness measures should be conducted with caution.