Ultrasound Assessment of Endothelial Function: A Technical Guideline of the Flow-mediated Dilation Test

Abstract

Cardiovascular disease is the primary cause of mortality and a major cause of disability worldwide. The dysfunction of the vascular endothelium is a pathological condition characterized mainly by a disruption in the balance between vasodilator and vasoconstrictor substances and is proposed to play an important role in the development of atherosclerotic cardiovascular disease. Therefore, a precise evaluation of endothelial function in humans represents an important tool that could help better understand the etiology of multiple cardio-centric pathologies. Over the past twenty-five years, many methodological approaches have been developed to provide an assessment of endothelial function in humans. Introduced in 1989, the FMD test incorporates a forearm occlusion and subsequent reactive hyperemia that promotes nitric oxide production and vasodilation of the brachial artery. The FMD test is now the most widely utilized, non-invasive, ultrasonic assessment of endothelial function in humans and has been associated with future cardiovascular events. Although the FMD test could have clinical utility, it is a physiological assessment that has inherited several confounding factors that need to be considered. This article describes a standardized protocol for determining FMD including the recommended methodology to help minimize the physiological and technical issues and improve the precision and reproducibility of the assessment.

Assessment of arterial function in pregnancy: recommendations of the International Working Group on Maternal Hemodynamics

“…supine or sitting) for at least 5 min before the tests commence. For FMD measurements, a resting position of around 20 min is recommended. Room temperature should be set at approximately 22–24 °C to control for orthostatic changes. As several medications that are commonly taken in pregnancy can affect arterial function, it is generally recommended that participants refrain from taking such medication for at least four half‐lives of the drug prior to testing, when possible and safe to do so.…”

Evaluation of the brachial artery endothelial function in chronic alcohol consumption among males by high‐frequency ultrasonography

“…After obtaining the baseline diameter of the brachial artery ( D 0 ), which was taken during the rest state, a cuff was tied onto the right forearm and inflated at 280–300 mm Hg for 4 minutes before deflating quickly to increase arterial flow and induce reactive hyperemia. Ultrasound imaging following reactive hyperemia is widely used and has been well validated to calculate endothelial‐dependent brachial artery FMD . Another measurement of the diameter of the brachial artery ( D 1 ) was obtained 90 seconds after the cuff was deflated completely.…”

“…Ultrasound imaging following reactive hyperemia is widely used and has been well validated to calculate endothelial-dependent brachial artery FMD. 8,13,17 Another measurement of the diameter of the brachial artery (D 1 ) was obtained 90 seconds after the cuff was deflated completely. Then, after the diameter of brachial artery reset back to its baseline value, 0.4 mg of nitroglycerin was administered sublingually.…”

Disparity between EndoPAT measurement and brachial artery flow-mediated vasodilatation in hypertensive patients

“…Brachial artery (BA) flow-mediated vasodilatation (FMD) and nitroglycerin-induced dilation (NMD) in brachial artery (BA) is well known indices for evaluating endothelial function. However, especially FMD measurements are sometimes difficult and the reproducibility is limited despite wellestablished guideline [1][2][3] . Well-equipped UNEXEF18G system in Japan, that has recently been developed, as the semiautomatic image chasing measurement system, can precisely measure BA FMD 4) .…”