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

Abstract

Purpose Immediately following reactive hyperemia, the arteries in some individuals constrict before they begin to dilate. We have defined this physiological response high flow-mediated constriction (H-FMC). The aim of this study was to describe the frequency of the H-FMC during reactive hyperemia in children and adolescents throughout a range of body mass index (BMI) values and investigate differences in flow-mediated dilation (FMD), cardiovascular, and anthropometric measures between those subjects who experience this phenomenon and those who do not. Methods FMD was assessed in 136 children and adolescents (61 male, 75 female; 13±3 years) by ultrasound imaging the brachial artery. H-FMC was characterized as the lowest point from the baseline brachial artery diameter immediately following reactive hyperemia cuff release. Independent t-tests were used to compare differences between subjects who demonstrated an H-FMC vs. Non-H-FMC. Results H-FMC was observed in 91 of the 136 participants (66.9%). No significant difference was found between H-FMC vs. 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 trending toward significance in H-FMC vs. Non-H-FMC individuals (91.8th±14.9thvs.84.6th±22.8th percentile, P=0.057). FMD was significantly lower in H-FMC vs. Non-H-FMC subjects (5.43±3.41vs.8.05±3.97%, P<0.001). If the H-FMC was added to the FMD there was no significant difference in dilation between H-FMC and Non-H-FMC individuals (8.03±3.27%vs.8.05±3.97%, P=0.977). Conclusion Approximately 67% of participants demonstrated the high flow-mediated constriction during reactive hyperemia with BMI percentile being higher and FMD lower in children and adolescents who displayed this phenomenon.

Intra‐ and interday reproducibility of high‐flow‐mediated constriction response in young adults

“…Presently, we have reported approximately 67% of children and adolescents and 69% of adults display an H-FMC during FMD assessment prior to a shear stress-mediated dilation of the brachial artery (Ostrem et al, 2015;Ostrem et al, unpublished data). The presence of an H-FMC significantly reduced FMD response of the brachial artery to hyperaemia compared to individuals without an H-FMC response when using a baseline diameter calculated during blood flow occlusion (Ostrem et al, 2015;Ostrem et al, unpublished data). However, the reproducibility of brachial artery H-FMC has not been described.…”

“…However, the absolute diameter change (Ostrem et al, 2015;Ostrem et al, unpublished data). Considering such a large number of children, adolescents and adults have displayed an H-FMC in previous studies (Dobrosielski et al, 2006;Ostrem et al, 2015) in conjunction with the current study's healthy young adult population, it could be postulated that an H-FMC may serve as an ancillary representation of healthy endothelial function and increased vessel distensibility. However, Dobrosielski et al (2006) reported that older males had less postocclusion brachial artery constriction compared to young males.…”

“…Historically, a pre-occlusion baseline has been utilized to calculate vessel response to reactive hyperaemia (Corretti et al, 2002;Thijssen et al, 2011). However, the absolute diameter change (Ostrem et al, 2015;Ostrem et al, unpublished data). Theoretically, consideration of a postocclusion diameter when determining peak FMD would be logical if the goal is to assess the total shear stress-mediated vessel change, as the postocclusion baseline may be the smallest brachial artery diameter in a majority of individuals.…”

“…FMD has been inversely associated with future CVD events (Brevetti et al, 2003;Katz et al, 2005;Muiesan et al, 2008;Ras et al, 2013). Recently, during FMD measurement in the brachial artery, we and others have reported a biphasic response to reactive hyperaemia, in which a vessel constriction phase occurs prior to a dilatory phase (Dobrosielski et al, 2006;Ostrem et al, 2015). This constriction phase during reactive hyperaemia has been termed highflow-mediated constriction (H-FMC).…”

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

“…high-flow) and ischaemia (i.e. low-flow) (Harrison et al, 2011;Weissgerber, 2014;Ostrem et al, 2015;Aizawa et al, 2016;Irace et al, 2016).…”