A healthy artery is wider and has no blockages. The lumen (which is the hole in the centre of the artery), is open and clear. This means there is more blood flow. An artery of a person suffering from coronary heart disease is often blocked, usually by a fatty deposit. This means the blood does not flow as well. (See diagram, in which I would draw two arteries, one with a blockage of fatty deposit, one clear and healthy).
