Intra- and inter-day reproducibility of low-flow mediated constriction response in young adults

Michelle M. Harbin, Joseph D. Ostrem, Nicholas G. Evanoff, Aaron S. Kelly, Donald R. Dengel

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: 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. Methods: 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%. Results: 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. Conclusion: 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.

Original languageEnglish (US)
Pages (from-to)502-507
Number of pages6
JournalClinical Physiology and Functional Imaging
Volume38
Issue number3
DOIs
StatePublished - May 2018

Bibliographical note

Funding Information:
The authors report no funding source. The authors would like to thank both the participants in this study and the School of Kinesiology at the University of Minnesota, Twin Cities.

Publisher Copyright:
© 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

Keywords

  • endothelial function
  • flow-mediated dilation
  • low-flow-mediated constriction
  • reactive hyperaemia
  • ultrasound

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