Endothelial dysfunction is a medical condition in which the inner lining of blood vessels called endothelium is affected due to abnormality in vasodilatation and vasoconstriction of blood vessels. The normal endothelium helps in coagulation, adhesion of platelets, immune processes, regulation of volume and electrolyte balance in the extra and intravascular spaces. Endothelial dysfunction occurs from or results in Behcet's disease in hypertension, atherosclerosis, coronary artery disease, hypercholesterolaemia, septic shock, diabetes. Chemokines or cytokines released from abnormal endothelium causes inflammation and subsequent fibrosis in the walls of arteries leading to atherosclerosis. Smoking and air pollution are contributing factors for the disease. Reduction in the bioavailability of Nitric Oxide (NO) is an important feature of Endothelial Dysfunction. The arteries and arterioles fail to dilate fully in response to stimuli as a result of which there is impaired production of nitrous oxide. The quantity of available NO is tested using methods like administration of vasoactive agents to parts of blood vessels, iontophoresis of acetylcholine, angiography with acetylcholine injection, local heating of skin and temporary occlusion of arteries by inflating sphygmomanometer cuff to very high pressures. Intracoronary catheterization may also be done in some required cases.
Flow-mediated dilation is the most commonly used test, in which FMD is measured by Brachial Artery Ultrasound Imaging. EndoPAT™ by Itamar Medical is a FDA approved non invasive device used to determine endothelial dysfunction by measuring Reactive Hyperemia Index (RHI). Recent Research has found that implantation of stents decreases the normal functioning of the endothelium. Pharmacological interventions to improve the endothelium includes use of rennin-angiotensin inhibitors, statins etc. Consumption of fruits and vegetables rich in flavenoids, potassium, and arginine improves endothelial function. Excess intake of Trans fat (margarine) deteriorates the endothelium and should be avoided as much as possible. Latest 3rd generation 5-phosphodiesterase and β-blockers may affect the endothelial functions.
Disclaimer: The information given in this write-up is purely for educating the reader. It is not meant to be a substitute for any advice from a medical expert.