| dc.description.abstract | Purpose: Macrovascular endothelial function is commonly assessed using flow-mediated dilation (FMD) and is nitric oxide (NO) dependent. However, the vasoreactivity to low flow during the FMD protocol may complement FMD interpretation. This study aimed to investigate in adolescents: (1) the day-to-day reliability of low-flow-mediated constriction (L-FMC) and composite vessel reactivity (CVR); and (2) the relationship between L-FMC and FMD. Methods: A retrospective analysis of data on 27 adolescents (14.3 ± 0.6 year, 12 males) was performed. Participants had two repeat measures, on separate days, of macrovascular function using high-resolution ultrasound for assessment of L-FMC, FMD, and CVR. Results: On average, the L-FMC response was vasoconstriction on both days (−0.59 ± 2.22% and −0.16 ± 1.50%, respectively). In contrast, an inconsistent response to low flow (vasoconstriction, dilation, or no change) was observed on an individual level. Cohen's Kappa revealed poor agreement for classifying the L-FMC measurement between visits (k = 0.04, P >.05). Assessment of the actual vessel diameter was robust with a coefficient of variation of 1.7% (baseline and peak) and 2.7% (low-flow). The between-day correlation coefficient between measures was r =.18, r =.96 and r =.52 for L-FMC, FMD, and CVR, respectively. No significant correlation between FMD and L-FMC was observed for either visit (r = −.06 and r = −.07, respectively; P >.05). Conclusion: In adolescents, the low-flow vasoreactivity is inconsistent between days. Whereas the actual vessel diameter is reproducible, the measurement of L-FMC and CVR has poor between-day reliability compared to FMD. Finally, L-FMC, and FMD are not significantly correlated. | en_GB |
