Expert consensus and evidence-based recommendations for the assessment of flow-mediated dilation in humans

Abstract

Endothelial dysfunction is involved in the development of atherosclerosis, which precedes asymptomatic structural vascular alterations as well as clinical manifestations of cardiovascular disease (CVD). Endothelial function can be assessed non-invasively using the flow-mediated dilation (FMD) technique. Flow-mediated dilation represents an endothelium-dependent, largely nitric oxide (NO)-mediated dilatation of conduit arteries in response to an imposed increase in blood flow and shear stress. Flow-mediated dilation is affected by cardiovascular (CV) risk factors, relates to coronary artery endothelial function, and independently predicts CVD outcome. Accordingly, FMD is a tool for examining the pathophysiology of CVD and possibly identifying subjects at increased risk for future CV events. Moreover, it has merit in examining the acute and long-term impact of physiological and pharmacological interventions in humans. Despite concerns about its reproducibility, the available evidence shows that highly reliable FMD measurements can be achieved when specialized laboratories follow standardized protocols. For this purpose, updated expert consensus guidelines for the performance of FMD are presented, which are based on critical appraisal of novel technical approaches, development of analysis software, and studies exploring the physiological principles underlying the technique. Uniformity in FMD performance will (i) improve comparability between studies, (ii) contribute to construction of reference values, and (iii) offer an easy accessible and early marker of atherosclerosis that could complement clinical symptoms of structural arterial disease and facilitate early diagnosis and prediction of CVD outcomes.

Ubiquinol Ameliorates Endothelial Dysfunction in Subjects with Mild-to-Moderate Dyslipidemia: A Randomized Clinical Trial

“…Ubiquinol treatment for 8 weeks induced a mean 1.3% FMD increase in both treated groups that was significant and did not seem to be dose-dependent. According to the latest consensus report, each 1% point increase in FMD involves a significant 8%-13% reduction in the risk of cardiovascular events [33].…”

“…Our study has several strengths, including the evaluation of plasma CoQ10 at both time points, which allowed demonstrating participant compliance. Moreover, we closely followed the latest FMD assessment guidelines [33], including the requirement that FMD be measured by the same trained sonographer, the use of a stereotactic probe-holder to maintain the same scan throughout the examination, and the continuous measurement of post-deflation diameter, to capture the actual brachial artery peak diameter. Some limitations also need to be discussed.…”

“…FMD was expressed as a percent ratio of the maximum increment of the brachial artery diameter in the post-deflation phase to the baseline diameter. All measurements were taken by the same trained sonographer and assessed by a blinded observer at the end of the study in accordance with current guidelines [33]. Both the sonographer and the observer were blinded to treatment allocation.…”

The effects of pulmonary rehabilitation on endothelial function and arterial stiffness in patients with chronic obstructive pulmonary disease

“…The gold standard for non‐invasive measurement of endothelial function is the flow‐mediated dilation (FMD) of the brachial artery with high‐resolution ultrasound (Deanfield, Halcox, & Rabelink, ). Although FMD is a popular and widely used technique (Thijssen et al, ), it is strongly operator dependent and has a significant learning curve (Corretti et al, ). In addition, vasodilatation is only measured in one arm, which precludes the correction for autonomous activation of the nervous system.…”

“…Although FMD is a popular and widely used technique (Thijssen et al, 2019), it is strongly operator dependent and has a significant learning curve (Corretti et al, 2002). In addition, vasodilatation is only measured in one arm, which precludes the correction for autonomous activation of the nervous system.…”