Presence of a high-flow-mediated constriction phenomenon prior to flow-mediated dilation in normal weight, overweight, and obese children and adolescents

Purpose: 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±14.9th 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.