Harbin Michelle M, Ostrem Joseph D, Evanoff Nicholas G, Kelly Aaron S, Dengel Donald R
Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.
Kinesiology and Health Sciences, College of Education and Science, Concordia University, Paul, MN, USA.
Clin Physiol Funct Imaging. 2018 May;38(3):502-507. doi: 10.1111/cpf.12448. Epub 2017 Jun 2.
When assessing brachial endothelial function by reactive hyperaemia, stopping blood flow creates a period of low-flow-mediated constriction (L-FMC). As little is known about how this parameter influences flow-mediated vasodilation (FMD), the purpose of this study was to better understand this relationship and to determine the intra- and interday reproducibility of brachial L-FMC.
Brachial L-FMC and FMD were measured on 26 healthy, young adults (13 males, 13 females; 24·6 ± 2·7 years). Each participant had two assessments conducted on two separate visits, separated by a minimum of seven days. Brachial artery baseline diameter was imaged during rest. Continuous imaging of the artery was performed during the last 20 s of cuff-occlusion to 180 s postcuff release. An L-FMC was considered present if the relative change from pre-occlusion baseline to L-FMC artery diameter was less than -0·1%.
Overall, there was a strong, positive correlation between increased brachial L-FMC and blunted FMD (visit 1 test 1: r = 0·758, P<0·001; visit 1 test 2: r = 0·706, P<0·001; visit 2 test 1: r = 0·836, P<0·001; visit 2 test 2: r = 0·857, P<0·001). The reproducibility of intra- and interday L-FMC diameter was intraclass correlation coefficients (ICC) = 0·627, coefficient of variation (CV) = 54·4% and ICC = 0·734, CV = 43·5%, respectively.
Vasoconstriction to low-flow conditions influences the subsequent maximal dilation during reactive hyperaemia. However, L-FMC is variable as evidenced by the weak intra- and interday reproducibility of the measure. Further research should study brachial L-FMC reproducibility among varying populations and the implications L-FMC has on the interpretation of FMD results.
在用反应性充血评估肱动脉内皮功能时，阻断血流会产生一段低流量介导的血管收缩期（L - FMC）。由于对该参数如何影响血流介导的血管舒张（FMD）知之甚少，本研究的目的是更好地理解这种关系，并确定肱动脉L - FMC的日内和日间重复性。
对26名健康的年轻成年人（13名男性，13名女性；24.6±2.7岁）测量肱动脉L - FMC和FMD。每位参与者在两次单独的就诊中进行两次评估，间隔至少7天。在静息状态下对肱动脉基线直径进行成像。在袖带阻断的最后20秒至袖带松开后180秒期间对动脉进行连续成像。如果从阻断前基线到L - FMC动脉直径的相对变化小于 -0.1%，则认为存在L - FMC。
总体而言，肱动脉L - FMC增加与FMD减弱之间存在强正相关（就诊1测试1：r = 0.758，P<0.001；就诊1测试2：r = 0.706，P<0.001；就诊2测试1：r = 0.836，P<0.001；就诊2测试2：r = 0.857，P<0.001）。日内和日间L - FMC直径的重复性分别为组内相关系数（ICC）= 0.627，变异系数（CV）= 54.4%和ICC = 0.734，CV = 43.5%。
对低流量状态的血管收缩会影响随后反应性充血期间的最大舒张。然而，L - FMC是可变的，该测量的日内和日间重复性较弱证明了这一点。进一步的研究应探讨不同人群中肱动脉L - FMC的重复性以及L - FMC对FMD结果解释的影响。
