Peripheral artery disease: Pathology review

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Case Study0:00–0:41

Tariq is a 52-year-old individual who presents to the clinic complaining of left leg pain. He describes the pain as “cramping” and mostly located in his calf.
He also mentions that the pain comes every time he walks from his home to the supermarket, and is relieved when he rests.
Tariq also has a known history of hypertension, diabetes mellitus, and a myocardial infarction 2 years ago. On physical examination, there is a noticeable decrease in hair growth on the left side compared to the right, and the skin appears dry and shiny.
There is no leg swelling, and there’s no back pain.Peripheral artery disease is insufficient tissue perfusion due to narrowing or occlusion of the aorta or one of its peripheral branches supplying the limbs.

Pathology0:41–1:21

Similar to coronary artery and cerebrovascular disease, the development of an atherosclerotic plaque that narrows or completely occludes an artery is the number one cause of peripheral artery disease, and so these diseases often coexist together.
So on the exam, an important clue may be an individual with a past medical history of a myocardial infarction or a stroke.
In addition, look for risk factors of atherosclerosis, such as hypertension, diabetes mellitus, smoking and hyperlipidemia.The symptoms of peripheral artery disease depend on how bad the occlusion is.

Symptoms1:21–3:01

In the early stages of the disease individuals may be completely asymptomatic. One of the first symptoms is intermittent claudication.
This is characterized by cramping pain in the affected area that comes about during exercise, and is relieved with rest.
Individuals often describe a specific and often consistent distance that brings about the pain, such as walking 2 blocks.
The location of the pain can also help give a clue about which artery is occluded. For example, hip claudication indicates aortic or iliac artery occlusion, whereas calf claudication points towards femoral or popliteal artery occlusion.
In addition to claudication, chronic limb ischemia may produce some physical changes. This includes a decrease in the skin temperature, called poikilothermia.
Also, hair and nail growth decrease, and sensation can be lost. On physical exam, the pulse distal to the obstruction is weak, and there’s diminished capillary refill in the affected area.As the arterial narrowing worsens, individuals begin to complain of pain at rest.
This is classically worse at night when the individual is sleeping, and gets better when they stand up or hang their leg off of the bed, due to the effect of gravity on blood flow.
Eventually, the peripheral tissue dies, which manifests as gangrene and ulcers. The end-stage manifestation is critical limb ischemia, which includes pain at rest as well as tissue loss in the form of gangrenes and ulcers.
Critical limb ischemia is limb-threatening if operative intervention is not performed.For diagnosis, when there’s suspicion of peripheral artery disease, an ankle-brachial index test, or ABI is performed.

Diagnosis3:01–3:51

ABI is the ratio of ankle systolic blood pressure to brachial systolic blood pressure. Normally, both pressures should be equal, and so the ratio should be equal to 1.
In individuals with intermittent claudication, the ABI usually lies somewhere between 0.4 and 0.9, since the blood pressure in the ankle is decreased.In severe peripheral artery disease, usually when the individual begins to develop resting pain, the ABI is less than 0.4.
After doing the ABI, the diagnosis is further confirmed with imaging, such as ultrasound or CT angiography. For treatment, lifestyle changes like exercise programs and diet are the first steps.

Treatment3:51–4:27

For medication, Cilostazol, a phosphodiesterase inhibitor, can directly dilate the arteries, easing symptoms. In addition it’s an antiplatelet which can prevent platelet aggregation and decrease the risk of thrombosis.
Even without Cilostazol, they should still take an antiplatelet medication like aspirin as prevention for coronary artery disease and stroke.
Now, when there’s severe obstruction and tissue necrosis, endovascular or surgical procedures are done to preserve the affected limb.Now, let’s take a look at some of the other less common causes of peripheral artery disease other than atherosclerosis.

Causes4:27–5:44

Although they’re less common, they make for good exam questions. Think of these when the case is of someone with no atherosclerotic risk factors.
First, vasculitides can cause peripheral vessel occlusion. A particularly high yield one is Thromboangiitis obliterans.
This affects individuals between 20 and 40 years, and commonly occurs in people who smoke, and can cause claudication in the feet, calves and hands.
An additional high yield clue is the presence of Raynaud’s phenomenon, which is a gradual discoloration of the hands from white to blue and then to red, and happens following exposure to cold.
A popliteal artery aneurysm is another potential cause. Due to the stasis of the blood in the area of the aneurysm, a clot can form.
That clot can then embolize and occlude smaller vessels in the legs. In addition, atrial fibrillation can dislodge clots that travel from the heart to the limbs, causing the same kinds of problems.
A high yield concept is that with an arterial embolus, there is a sudden onset of symptoms, rather than the gradual onset of symptoms caused by atherosclerosis.All right, next are important mimickers of peripheral artery disease that should be on your differential diagnosis list.

Differential Diagnosis5:44–6:50

First is deep vein thrombosis, which can also present with leg pain. However, deep vein thrombosis is usually associated with leg swelling and redness, and individuals have risk factors such as immobility or hypercoagulability.
Next is lumbar spinal stenosis, a condition in which the central canal or neural foramina of the vertebrae are narrowed due to degenerative changes associated with aging.
Because it compresses the nerves that run down the leg, individuals present with unilateral or bilateral leg pain that is worse with walking and is relieved with rest.This presentation is very similar to peripheral artery disease, but you can tell them apart since when the pain is neurogenic, the peripheral pulses should be completely normal.
In addition, the pain in neurogenic claudication is also relieved by flexing the back, or bending forward, and is worsened by extending the back, or bending backward.All right, as a quick recap...Peripheral artery disease is narrowing of the peripheral arteries, usually because of atherosclerosis, but other causes include vasculitis and arterial emboli.

Review6:50–7:46

Individuals typically present with a spectrum of symptoms, ranging from intermittent claudication, to resting pain, to eventually developing gangrene and ulcers.
Other symptoms of chronic ischemia include hair loss in the affected area, dry skin, decreased peripheral pulses and loss of sensation.
The diagnosis is initially made by performing an ankle-brachial-index, with an ABI less than 0.9 being abnormal. Imaging with ultrasound or CT angiography further determines the location and extent of arterial narrowing.
Important differential diagnoses to consider include deep vein thrombosis and lumbar spinal stenosis.Okay, back to our case.

Summary7:46–8:29

Tariq is presenting with symptoms suggestive of intermittent vascular claudication. The pain is reproducible when he walks a certain distance, in his case, to the supermarket.
Supporting the diagnosis, Tariq has risk factors for atherosclerosis like hypertension and diabetes and also has a history of a myocardial infarction.
In addition, he has physical signs of peripheral artery disease, like decreased hair growth. He also doesn’t appear to have symptoms of the mimickers, with no leg swelling and no back pain.
Tariq underwent an ABI test, which showed a ratio of 0.5. CT angiography confirmed narrowing of his left femoral artery, which is consistent with the location of his pain in
Peripheral artery disease: Pathology Review: Video | Osmosis