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

Area of Science:

• Cardiovascular physiology
• Vascular biology
• Endothelial function assessment

Background:

• Flow-mediated dilation (FMD) assesses brachial artery function post-ischemia.
• Brachial artery constriction during ischemia (L-FMC) is inconsistently reported.
• The clinical significance of L-FMC remains unclear.

Purpose of the Study:

• Determine the prevalence of L-FMC in outpatients.
• Correlate L-FMC magnitude with FMD magnitude.
• Investigate L-FMC's predictive value for FMD timing.

Main Methods:

• 179 outpatients underwent 5-minute forearm ischemia with serial brachial artery diameter measurements.
• Constrictors were defined as >1% diameter reduction during ischemia.
• FMD was assessed post-cuff release; dilation timing categorized subjects as Early, Late, or No dilators.

Main Results:

• 39% of subjects (70/179) demonstrated L-FMC.
• Greater L-FMC magnitude correlated with lower post-ischemic dilation.
• Constrictors were significantly more likely to be Late or No dilators (p<0.05).

Conclusions:

• L-FMC is prevalent in nearly 40% of individuals.
• Increased L-FMC is associated with impaired FMD.
• L-FMC may serve as a potential biomarker for endothelial dysfunction.