Plaque build up. It is hardening of the arteries, caused by fat, cholesterol, and other substances building up in the arteries - this is called plaque - making the arteries stiffer. This plaque interferes with the normal function of the arteries and can cause problems and symptoms throughout the body. The plaque can block the arteries and/or it can break off and flow to smaller vessels and block them.
Enlarge Then Narrow. Atherosclerosis: an accumulation of white blood cells, mostly macrophages, which have invaded into the walls of the blood vessel to remove low density lipoprotein (fat carrying protein) particles. The artery wall thickens and enlarges, protecting blood flow. However, rupture of the endothelium, over an atherosclerotic plaque, sheds debris downstream, induces clots and can result in sudden closure.