title: Presence of a high-flow-mediated constriction phenomenon prior to flow-mediated dilation in normal weight, overweight, and obese children and adolescents.
abstract: OBJECTIVE
  When assessing vasomotor endothelial function by reactive hyperemia, the brachial artery, in some individuals, constricts immediately before beginning to dilate following cuff release. We call this response high-flow-mediated constriction (H-FMC). The aim of this study was to describe the rate of the H-FMC during reactive hyperemia in children and adolescents throughout a range of body mass index (BMI) values, and to investigate differences in flow-mediated dilation (FMD), cardiovascular, and anthropometric measures between subjects with and without H-FMC.
  
  
  METHODS
  FMD was assessed in 136 children and adolescents (61 male, 75 female; 13 ± 3 years) by sonographic imaging of the brachial artery. H-FMC was characterized as the lowest point from the baseline brachial artery diameter immediately following reactive cuff release. Independent t tests were used to compare subjects with and without H-FMC.
  
  
  RESULTS
  H-FMC was observed in 91 of the 136 participants (66.9%). No significant difference was found between H-FMC and non-H-FMC subjects for age (p = 0.602), gender (p = 0.767), height (p = 0.227), or weight (p = 0.171). BMI percentile was nonsignificantly higher (91.8 ± 4.9th versus 84.6 ± 22.8th percentile, p = 0.057) and FMD was significantly lower (5.43 ± 3.41% versus 8.05 ± 3.97%, p < 0.001) in H-FMC than in non-H-FMC subjects. Adding H-FMC to FMD produced no significant difference between H-FMC and non-H-FMC individuals (8.03 ± 3.27% versus 8.05 ± 3.97%, p = 0.977).
  
  
  CONCLUSIONS
  Approximately 67% of participants demonstrated an H-FMC during reactive hyperemia. BMI percentile was nonsignificantly higher and FMD was significantly lower in children and adolescents who displayed this phenomenon.
authors: Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN 55455.
authors: Joseph D
authors: JD
authors: Ostrem
authors: Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN 55455.
authors: Nicholas
authors: N
authors: Evanoff
authors: Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455.|Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455.
authors: Aaron S
authors: AS
authors: Kelly
authors: Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN 55455.|Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455.
authors: Donald R
authors: DR
authors: Dengel
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002648:Child; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D050177:Overweight / Q000503:physiopathology*; D018570:Risk Assessment; D014463:Ultrasonography; D014661:Vasoconstriction
keywords: adolescents; flow-mediated constriction; flow-mediated dilation; reactive hyperemia; ultrasound