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Updated: Jul 3, 2026
Ultrasound Assessment of Endothelial Function: A Technical Guideline of the Flow-mediated Dilation Test
Published on: April 27, 2016
Evaluation of endothelial dysfunction: flow-mediated dilation
1Department of Cardiology, Elazig Education and Research Hospital, Elazig, Turkey. hkorkmaz23@yahoo.com
Insights
Early detection of endothelial dysfunction using noninvasive methods like brachial artery flow-mediated dilation (FMD) is key for preventing advanced atherosclerotic disease. This simple technique assesses early vascular changes and monitors treatment effectiveness.
Area of Science:
- Vascular Biology
- Cardiovascular Medicine
- Diagnostic Methods
Background:
- Atherosclerotic disease is often diagnosed at advanced stages, with treatments typically being palliative.
- Endothelial dysfunction represents an early, subclinical change crucial for disease prevention.
- Peripheral artery assessment using noninvasive methods offers accurate insights into systemic endothelial health.
Purpose of the Study:
- To highlight the significance of detecting and treating endothelial dysfunction in the early stages of atherosclerotic disease.
- To introduce the flow-mediated dilation (FMD) method as a noninvasive tool for assessing endothelial function.
- To discuss the potential of FMD in monitoring therapeutic interventions for endothelial dysfunction.
Main Methods:
- Utilizing ultrasonography on the brachial artery to measure flow-mediated dilation (FMD).
- Employing a sphygmomanometer to induce reactive hyperemia via temporary ischemia in the forearm.
- Calculating FMD as the percentage change in brachial artery diameter post-ischemia.
Main Results:
- Flow-mediated dilation (FMD) is a reliable, noninvasive method for assessing endothelial dysfunction.
- Various treatments, including ACE inhibitors, ARBs, certain beta-blockers, statins, estrogen, diet, and exercise, have been shown to improve FMD.
- The FMD method allows for monitoring the impact of interventions on endothelial function.
Conclusions:
- Early detection of endothelial dysfunction via noninvasive methods like FMD is critical for cardiovascular disease (CVD) prevention.
- Standardization of FMD measurement techniques and values is necessary for its routine clinical adoption.
- FMD serves as a valuable biomarker for assessing vascular health and treatment efficacy.
Abstract:
By the time the clinical findings of atherosclerotic disease appear, involvement is usually at an advanced stage and procedures after this stage are usually palliative or aimed at secondary protection. On the other hand, prevention can be achieved by the detection and treatment of endothelial dysfunction, which is one of the most important changes in the early subclinical stage of atherosclerotic disease. When the systemic involvement of endothelial dysfunction is taken into consideration, checking from the peripheral arteries with noninvasive methods gives one-to-one correct information. Currently, endothelial dysfunction can be detected using simple, inexpensive, and noninterventional methods. Particularly, easily accessible localization of the brachial artery is ideal for the evaluation of endothelial dysfunction. Flow-mediated dilation method (FMD; endothelial-dependent vasodilation), which can be carried out noninvasively with ultrasonography on the brachial artery, is a frequently used method for the assessment of endothelial dysfunction. A sphygmomanometer is placed on the forearm to create a flow stimulation in the brachial artery. The sphygmomanometer is inflated until the systolic pressure is above 50 mm Hg, thus stopping the antegrade blood flow and creating ischemia. Consequently, vasodilation occurs at the resistance arteries distal to where the flow is blocked. When the sphygmomanometer is deflated, a reactive hyperemia occurs in the brachial artery. The % difference between the diameter measured after reactive hyperemia and the basal diameter is taken as FMD. The effects of the treatments on endothelial dysfunction can be monitored with this method. Studies have shown that angiotensin-converting enzyme (ACE) inhibitors, angiotensin 1 (AT1) receptor blockers, latest-generation beta blockers such as nebivolol and carvediol, statins, estrogen treatment, diet, and exercise increase FMD. Before this method becomes a part of routine clinical evaluation of cardiovascular disease (CVD) risk, measurement technique and FMD values need to be standardized.
