Arteriosclerosis, a term that refers to the hardening and thickening of the arteries, is responsible for the majority of deaths in the United States. Atherosclerosis is the most common form; other types include focal calcific arteriosclerosis and arteriosclerosis obliterans. Regardless of the type, all forms of arteriosclerosis are characterized by a buildup in the arteries, either of plaque or calcium.