AIM:Flow-mediated vasodilation (FMD) of the brachial artery measures the ability of the artery to dilate after a forearm ischemia lasting for 5 min. During ischemia, and therefore in conditions of low flow, constriction of the brachial artery (L-FMC) has sometimes been reported. The meaning of L-FMC is still unclear. The aims of our study were to establish the prevalence of subjects with L-FMC, to determine whether the magnitude of L-FMC correlates with magnitude of FMD, and to determine whether L-FMC can be used to predict FMD timing.METHODS:A total of 179 outpatients were studied, and the brachial artery diameter was measured every minute during the 5 min forearm ischemia. Subjects who had at least one measurement showing a constriction of > 1% during ischemia were defined as constrictors. FMD was evaluated at 50 s, 2 min, and 3 min after cuff release. On the basis of time, the subjects in whom maximal dilation had occurred were divided into Early, Late, or No dilators.RESULTS:The brachial artery diameter of 70 subjects (39%) constricted during ischemia. Higher the constriction during ischemia, lower was the dilation after ischemia. Constrictors were more likely to have Late (OR 2.6; ICs 95% 1.19-5.81, p=0.02) or No dilation (OR 4.8; ICs 95% 1.90-12-16, p=0.02) compared with no constrictors.CONCLUSIONS:The present study reveals that almost 40% of the subjects had brachial artery L-FMC and a more pronounced constriction during ischemia correlated with a lower dilation after ischemia. Finally, the prevalence of subjects showing L-FMC was significantly higher among subjects with delayed or no vasodilation, suggesting that L-FMC may be a marker of endothelial dysfunction.

Brachial Low-Flow-Mediated Constriction is Associated with Delayed Brachial Flow-Mediated Dilation

Irace C;Gnasso A
2016-01-01

Abstract

AIM:Flow-mediated vasodilation (FMD) of the brachial artery measures the ability of the artery to dilate after a forearm ischemia lasting for 5 min. During ischemia, and therefore in conditions of low flow, constriction of the brachial artery (L-FMC) has sometimes been reported. The meaning of L-FMC is still unclear. The aims of our study were to establish the prevalence of subjects with L-FMC, to determine whether the magnitude of L-FMC correlates with magnitude of FMD, and to determine whether L-FMC can be used to predict FMD timing.METHODS:A total of 179 outpatients were studied, and the brachial artery diameter was measured every minute during the 5 min forearm ischemia. Subjects who had at least one measurement showing a constriction of > 1% during ischemia were defined as constrictors. FMD was evaluated at 50 s, 2 min, and 3 min after cuff release. On the basis of time, the subjects in whom maximal dilation had occurred were divided into Early, Late, or No dilators.RESULTS:The brachial artery diameter of 70 subjects (39%) constricted during ischemia. Higher the constriction during ischemia, lower was the dilation after ischemia. Constrictors were more likely to have Late (OR 2.6; ICs 95% 1.19-5.81, p=0.02) or No dilation (OR 4.8; ICs 95% 1.90-12-16, p=0.02) compared with no constrictors.CONCLUSIONS:The present study reveals that almost 40% of the subjects had brachial artery L-FMC and a more pronounced constriction during ischemia correlated with a lower dilation after ischemia. Finally, the prevalence of subjects showing L-FMC was significantly higher among subjects with delayed or no vasodilation, suggesting that L-FMC may be a marker of endothelial dysfunction.
2016
endothelial constriction; endothelial dilation; endothelial function
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12317/14056
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