The primary cause of PAD is atherosclerosis, a slowly developing condition in which fatty deposits cling to an artery wall. To heal the damage, an artery wall releases chemicals that encapsulate and stabilize the plaque. However, these chemicals are sticky, attracting inflammatory cells, calcium and proteins. These deposits, called plaque, narrow and harden arteries.
Plaque deposits are hard on the outside and soft on the inside. If a deposit's tough exterior cracks, the body will try to seal the rupture by releasing blood-clotting platelets, which further narrows an artery.
When an artery becomes blocked completely, surrounding soft tissue can be damaged by a lack of oxygen and nutrient-rich blood flow. This loss of circulation, called ischemia, explains why patients with PAD can develop gangrene and risk amputation of their toes.
Less common causes of PAD include trauma to the arms or legs, infection and muscular or ligament irregularities. Individuals with PAD also may have coronary artery disease.