Peripheral artery disease

Vascular refers to the blood vessels, and peripheral means the outer limits or edge of something, which in peripheral vascular disease refers to any vessels that aren’t supplying the heart or the brain, like ones in the legs, arms, or other organs. Peripheral vascular disease happens when one of these arteries becomes narrowed, which reduces blood flow; this often affects the limbs.

Peripheral vascular disease, or PVD, usually involves the arteries, so sometimes it’s also referred to as peripheral artery disease or PAD. PVD is usually caused by a blockage, called organic PVD, that is most commonly created by atherosclerosis. Atherosclerosis is a buildup of lipids and fibrous material just under the inner lining of the blood vessel, called the tunica intima. When plaque builds up, it narrows the artery, which reduces perfusion to whatever tissue it tends to supply; this buildup usually happens over the course of many years. However, the vessel could be blocked by an embolus, which can happen suddenly if a blood clot from some upstream artery lodges in a peripheral artery; this clot would obviously stop blood flow from getting to the tissue the vessel supplies.

Besides organic PVDs, there are also functional PVDs. With functional PVDs, blood vessels stop blood flow by changing diameter, such as with vasospasms, where the vessel constricts and blood flow is reduced. This type of PVD is usually short term, and can come and go.

The arteries supplying the legs are the most commonly affected vessels in peripheral vascular disease. When less blood gets to the muscle tissue in the legs, the tissue receives less oxygen and becomes ischemic. Ischemic cells release adenosine, a type of signaling molecule, which is thought to affect nerves in these areas; this is felt as pain. This pain in the legs is often referred to as claudication. Sometimes, even though blood flow is narrowed with PVD, when a person is at rest, there’s enough of blood to meet the tissue’s demands; thus, people are often asymptomatic during rest.

However, if the person is walking or exercising, then the leg muscles start to work harder and demand more oxygen; demand becomes greater than what’s supplied, which causes the claudication, or pain. The location of the pain is a clue to which artery is involved. If it’s in the hips and the buttocks, think of lower aorta or iliac. If it’s the thigh, think of the iliac or common femoral artery. For the upper 2/3 of the calf, think of the superficial femoral artery; for the lower ⅓ of the calf, think of the popliteal artery. Finally, for the foot, think of the tibial or peroneal artery.