AssessmentsPeripheral artery disease
Peripheral artery disease
USMLE® Step 1 style questions USMLE
A 73-year-old man comes to the emergency department with sudden, severe leg pain. He was watching football at home when he experienced an acute-onset, sharp pain in the right calf that has progressively worsened. The patient reports being unable to feel the sock worn on that foot, and he is having difficulty moving his toes. He denies chest pain or shortness of breath. Medical history is significant for a small intracranial aneurysm that has been monitored on serial imaging and has remained stable in size for five years. The patient’s temperature is 37.0°C (98.6°F), pulse is irregularly irregular at 90/min, respirations are 20/min, and blood pressure is 135/85 mmHg. Physical exam shows pale and mottled skin starting 6 cm below the right tibial plateau and extending to the right toes. There is no swelling. Hair growth is normal. Carotid, radial, and femoral pulses are palpable bilaterally. The left posterior tibial artery pulse is palpable while his right is absent on palpation and has no signal on Doppler ultrasound. Which of the following locations is the most likely origin of this patient’s embolus?
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.
Peripheral vascular disease or PVD refers to the narrowing of the arteries other than those which supply the heart and the brain. It most commonly affects the legs, but other arteries may also be involved. PVD can be organic, where the narrowing is caused by a blockage, or functional, where the blood vessel is constricted.
PVD causes a reduction in blood flow to the tissue supplied by the artery, resulting in tissue ischemia, gangrene, and necrosis. The classic symptom is leg pain when walking which resolves with rest, known as intermittent claudication. Other symptoms including skin ulcers, bluish skin, cold skin, or poor nail and hair growth may occur in the affected leg. Treatment involves lifestyle changes, medication to reduce clotting, or rarely surgery.