Peripheral arterial disease refers to the narrowing of arteries outside the heart and brain, usually as the result of atherosclerosis or "hardening of the arteries" (a build up of fatty deposits on the inner wall of arteries). When the arteries become narrowed, the flow of blood to the target organs or tissues is reduced.

The arteries commonly affected are those carrying blood to the kidneys, stomach, arms and legs. Peripheral arterial disease often appears first in your legs, with the most common symptom being dull, cramping leg pain that occurs when exercising but stops when you stand still. This is known as "intermittent claudication".