Kranen Sascha H, Bond Bert, Williams Craig A, Barker Alan R
Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.
J Clin Ultrasound. 2019 Mar;47(3):133-138. doi: 10.1002/jcu.22664. Epub 2018 Nov 25.
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.
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.
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).
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.
大血管内皮功能通常采用血流介导的血管舒张（FMD）进行评估，且依赖于一氧化氮（NO）。然而，FMD方案中低流量时的血管反应性可能有助于补充对FMD的解读。本研究旨在调查青少年：（1）低流量介导的血管收缩（L-FMC）和复合血管反应性（CVR）的日常可靠性；（2）L-FMC与FMD之间的关系。
对27名青少年（14.3±0.6岁，12名男性）的数据进行回顾性分析。参与者在不同日期使用高分辨率超声对大血管功能进行了两次重复测量，以评估L-FMC、FMD和CVR。
平均而言，两天的L-FMC反应均为血管收缩（分别为-0.59±2.22%和-0.16±1.50%）。相比之下，在个体水平上观察到对低流量的反应不一致（血管收缩、舒张或无变化）。Cohen's Kappa显示两次就诊之间L-FMC测量的一致性较差（k = 0.04，P > 0.05）。实际血管直径的评估具有稳健性，基线和峰值的变异系数为1.7%，低流量时为2.7%。两次测量之间的日间相关系数，L-FMC、FMD和CVR分别为r = 0.18、r = 0.96和r = 0.52。两次就诊时FMD与L-FMC之间均未观察到显著相关性（分别为r = -0.06和r = -0.07；P > 0.05）。
在青少年中，低流量血管反应性在不同日期之间不一致。虽然实际血管直径具有可重复性，但与FMD相比，L-FMC和CVR的测量在日间可靠性较差。最后，L-FMC与FMD无显著相关性。
