Postdeflation shear rate area under the curve correlated moderately with flow-mediated dilation in young adults (r2=0.14), but this relationship was absent in children and older adults.
Cross-Sectional (n=135)
No
Effect estimate: r2 0.14
p-value: p=0.005
Flow-mediated dilatation (FMD) has become a commonly applied approach for the assessment of vascular function and health in humans. Recent studies emphasize the importance of normalizing the magnitude of FMD to its apparent eliciting stimulus, the postdeflation arterial shear. However, the relationship between shear stress and the magnitude of FMD may differ between groups. The aim of this study was to examine the relationship between the brachial FMD and four different indexes of postdeflation shear rate (SR) in healthy children (n = 51, 10 +/- 1 yr) and young (n = 57, 27 +/- 6 yr) and older (n = 27, 58 +/- 4 yr) adults. SR was calculated from deflation (time 0) until 9 s (peak), 30 s (0-30), 60 s (0-60), or until the time-to-peak diameter in each individual (0-ttp). Edge detection and wall tracking of high resolution B-mode arterial ultrasound images were used to calculate the conduit artery diameter. In young adults, the brachial artery FMD demonstrated a significant correlation with the area under the SR curve (SR(AUC)) 0-30 s (r(2) = 0.12, P = 0.009), 0-60 s (r(2) = 0.14, P = 0.005), and 0-ttp (r(2) = 0.14, P = 0.005) but not for the peak SR(AUC) 0-9 s (r(2) = 0.04, P = 0.12). In children and older adults, the magnitude of the brachial artery FMD did not correlate with any of the four SR(AUC) stimuli. These findings suggest that in young subjects, postdeflation SR(AUC) correlates moderately with the magnitude of the FMD response. However, the relationship between FMD and postdeflation shear appears to be age dependent, with less evidence for an association in younger and older subjects. Therefore, we support presenting SR(AUC) stimuli but not normalizing FMD responses for the SR(AUC) when using this technique.
Thijssen et al. (Fri,) conducted a cross-sectional in Healthy volunteers (n=135). Flow-mediated dilatation (FMD) assessment vs. Comparison across age groups (children, young adults, older adults) was evaluated on Correlation between brachial artery FMD% and postdeflation shear rate area under the curve (SRAUC 0-60s) (r2 0.14, p=0.005). Postdeflation shear rate area under the curve correlated moderately with flow-mediated dilation in young adults (r2=0.14), but this relationship was absent in children and older adults.