Peripheral artery disease (PAD) occurs when the arteries in the extremities (usually legs and feet, sometimes arms and hands) become clogged with a fatty substance called plaque. It most often occurs in the legs. The build-up of plaque causes the arteries to become narrow and hard, obstructing blood flow. This hardening of the arteries is called atherosclerosis. (Atherosclerosis that affects arteries to the heart and brain is the major process leading to heart disease and stroke.)
PAD is a type of peripheral vascular disease, which also includes carotid artery disease, renal artery disease, aortic disease, venous problems, and some other conditions, such as vasculitis.