Evaluation of Endothelial Dysfunction: Flow-Mediated Dilation

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.

A Randomized Study of Allopurinol on Endothelial Function and Estimated Glomular Filtration Rate in Asymptomatic Hyperuricemic Subjects with Normal Renal Function

“…Endothelial dysfunction is considered a harbinger for hypertension and cardiovascular disease (16). FMD as a physiologic measure of endothelial function has been validated and used in many settings to investigate endothelial function (17). Several studies have reported an inverse relationship between uric acid and endothelial function/ FMD (13,18 -21), although this has not uniformly been noted (22).…”

A high oxidative stress index predicts endothelial dysfunction in young male smokers

“…It is already known that endothelial dysfunction assessment via FMD was clearly associated with atherosclerosis and its complications (20)(21)(22). Smoking, the major risk factor for coronary artery disease was also known to be associated with FMD (23,24).…”

An Assessment of Flow-Mediated Dilatation in Behçet’s Disease

“…[20] Endothelial cell dysfunction is widely accepted as an initial lesion in atherogenesis [4] and can be reversed with effective treatment. [11] It is known that cardiovascular risk factors such as smoking, hypertension, hyperlipidemia, DM, and obesity can cause ECD before the clinical findings of atherosclerosis are manifested. [11] Many authors have proven that inflammation is also an independent risk factor for this disease.…”

“…[11] It is known that cardiovascular risk factors such as smoking, hypertension, hyperlipidemia, DM, and obesity can cause ECD before the clinical findings of atherosclerosis are manifested. [11] Many authors have proven that inflammation is also an independent risk factor for this disease. [3][4][5][6][7][17][18][19] Indeed, ECD can be demonstrated in more than one vascular bed, and this is related to focal inflammation.…”

“…[8][9][10] By the time clinical findings of atherosclerosis appear, the disease is at an advanced stage, and treatment is palliative. [11] Endothelial cell dysfunction (ECD) is an important marker of atherosclerosis, and it also plays an important role in the development of vascular involvement in BD. [12,13] When systemic involvement of atherosclerosis is considered, the assessment of the peripheric arteries using a non-invasive method such as flow-mediated dilatation (FMD) provides accurate information, and this method is now used for the evaluation of ECD of the brachial artery with Doppler ultrasonography (US).…”