It is thought that PAD may be present to some degree in 20% of the population over 55. Risk factors include hypertension, hyperlipidemia, diabetes, and smoking. Stenosis or occlusion of an artery can cause symptoms ranging from intermittent claudication to ischemic rest pain to tissue loss and gangrene. The most common areas of stenosis or occlusion lie below the inguinal ligament and typically occur in the superficial femoral artery at the adductor canal, and in diabetics, in the tibial vessels. Aortoiliac disease occurs in the distal aorta and iliac arteries and is typically seen in younger patients, ages 35 to 55, with a history of heavy smoking and hyperlipidemia. An artery can be 80% blocked before symptoms occur. The most common presenting symptom in PAD is intermittent claudication caused by imbalance between oxygen supply and demand with exercise. It is often described as a cramping, heavy feeling or fatigue after walking certain distances that is relieved by rest. Intermittent claudication is not an indication for surgery; 70 to 80% of the patients remain stable, 10 to 29% worsen, but only 5 to 10% develop gangrene. Initially, medical management with risk factor modification and initiation of a walking program can be considered in patients without lifestyle-limiting claudication. Aspirin is usually recommended. Pentoxyfylline (Trental) and cilostazol (Pletal) are the only two drugs currently approved by the FDA for the treatment of claudication.