Narrowed carotid artery. Coloured digital angiogram (blood vessel X-ray) showing a narrowing (stenosis, arrowed) of the carotid arteries in the neck of a 59-year-old man. The angiography (use of a contrast medium to highlight blood vessels) shows irregularities in the carotid arteries that may indicate the presence of arterial disease and atheromatous plaques causing narrowing (stenosis) of the blood vessels. This could lead to a stroke if the blood supply to the brain is interrupted. This is a stenosis of the carotid bifurcation, at the level of the left internal carotid, with a narrowing greater than 75 percent.