Peripheral arterial disease, or PAD, reduces blood flow to the arms and legs to such a degree that the person has symptoms. It is most commonly caused by atherosclerosis, or hardening of the arteries.

What is going on in the body?

Atherosclerosis is a condition in which fatty deposits form inside blood vessel walls. This causes the walls to become thick and less elastic. The thickened areas are called plaques. When these plaques grow large enough or break apart, they can block the flow of blood through the arteries. The tissues that receive blood from these arteries then begin to suffer damage from a lack of oxygen. Peripheral arterial disease can also cause symptoms from narrowed arteries to the heart or brain.

What are the causes and risks of the disease?

Peripheral arterial disease is generally caused by atherosclerosis. Atherosclerosis is caused by an injury to the inside layer of the artery. It usually occurs where the artery bends or branches. Damage to the walls of the artery may be caused by a number of factors, including:

Atherosclerosis is more common in men than in women. A person's risk of atherosclerosis goes up as he or she ages. People who are sedentary are also at higher risk.

PAD may also be caused by a blood clot that lodges in an artery of the arm or leg.