Flow-mediated dilation

Flow-mediated dilation (FMD) is a test that measures how well your blood vessels can expand in response to increased blood flow. When blood flow increases, healthy arteries relax and widen, which helps maintain good circulation. During the test, a cuff temporarily blocks blood flow, then releases, causing a surge of blood through the artery. The device measures how much the artery widens afterward. This response reflects the health of your blood vessel lining (endothelium). A strong dilation indicates good vascular health, while reduced dilation can signal early signs of cardiovascular problems.