Variation in non-invasive measurements of vascular function in healthy volunteers during daytime.

Contains fulltext : 48255.pdf (publisher's version ) (Closed access)Although it is often recommended to standardize the time of day when performing non-invasive measurements of vascular function, the exact influence of the time of day on the outcome of IMT (intima-media thickness), PWV (pulse wave velocity), AIX (augmentation index) and FMD (flow-mediated dilatation) measurements has not been reported before. Nineteen healthy volunteers visited our department on two different occasions: the first visit was at 09:00 hours after an overnight fast, and the second visit was at 14:00 hours after a standardized breakfast. Non-invasive measurements of atherosclerosis were performed twice at 09:00 hours and once on the second visit at 14:00 hours. Measurement of IMT, PWV, AIX and FMD was reproducible according to the method of Bland and Altman. The absolute difference between repeated measurements at 09:00 hours showed no significant difference compared with the absolute difference between 09:00 and 14:00 hours for IMT (0.029+/-0.014 compared with 0.021+/-0.014 mm; P = 0.27), PWV (0.63+/-0.50 compared with 0.75+/-0.74 m/s; P = 0.52), AIX (4.0+/-4.0 compared with 5.5+/-5.2%; P = 0.35) and FMD (3.8+/-3.7 compared with 4.2+/-2.9%; P = 0.70). In conclusion, our results show that, in healthy volunteers during the daytime, IMT, PWV, AIX and FMD outcomes are not confounded by variation in the exact time of the examination as long as other (exogenous) conditions, including food intake, smoking and intake of alcohol, are carefully controlled for

The endothelium and its role in regulating vascular tone

The endothelium forms an important part of the vasculature and is involved in promoting an atheroprotective environment via the complementary actions of endothelial cell-derived vasoactive factors. Disruption of vascular homeostasis can lead to the development of endothelial dysfunction which in turn contributes to the early and late stages of atherosclerosis. In recent years an increasing number of non-invasive vascular tests have been developed to assess vascular structure and function in different clinical populations. The present review aims to provide an insight into the anatomy of the vasculature as well as the underlying endothelial cell physiology. In addition, an in-depth overview of the current methods used to assess vascular function and structure is provided as well as their link to certain clinical populations