Peripheral arterial disease (PAD) is a condition involving clogging of the arteries around the body, most commonly in the legs. PAD occurs more frequently as people get older and often goes hand-in-hand with coronary artery disease (CAD). PAD does most of its damage before any symptoms are seen.
PAD is caused by atherosclerosis (hardening of the arteries) or damaged arteries. If the arteries become narrowed or damaged, deposits of plaque, calcium, or cholesterol can settle in these areas and cause an obstruction.
Men, smokers, and seniors are more likely to develop PAD.
You also have a greater risk of developing PAD if you:
- have high blood pressure
- have high cholesterol or eat a high-fat diet
- are overweight or have a sedentary lifestyle
- have diabetes
- have a family history of atherosclerosis
- are a postmenopausal woman
Symptoms and Complications
Arteries carry oxygen-rich blood to the muscles. When an artery becomes narrower, it can't carry enough of the oxygen-rich blood to the muscle. This decrease in oxygen is called ischemia. A muscle that doesn't get enough oxygen feels painful, achy, cramped, and tired during physical activity. Skin that doesn't get enough nutrients can't heal quickly and can become infected easily.
Since most people who have PAD don't have any symptoms until the damage has begun, it's important to pay attention to possible signs or symptoms such as:
- leg pain when walking short distances, called intermittent claudication
- sores that are slow to heal on the leg or foot
- cold, pale, or bluish feet due to poor blood circulation
Symptoms of intermittent claudication are different depending on whether it's due to gradual or sudden narrowing of an artery. The first signs of a gradual narrowing include tiredness, aching, cramping, and pain in the calf, thigh, buttock, foot, or hip that starts during physical activity and eases with rest. The symptoms can be brought on by walking and are more noticeable when walking quickly or uphill. After a rest of up to 5 minutes, you can usually walk about as far as you did before resting. As the arterial narrowings get worse, the distance you can walk without remaining in pain gets shorter and shorter. At its worst, the pain comes on at rest and can keep you from sleeping.
Leg pain from PAD may keep you from exercising or walking around – the more it hurts, the less you will want to move. Since lack of exercise is one of the risk factors for PAD, this can make the situation worse.
If the blockage prevents blood from reaching the foot, the foot will become cold and numb. The skin on the foot may be dry and scaly, and the nails and hair won't grow properly. Sores might develop on the foot, especially on the toes or heel. When the blockage is quite severe, or the sores and infections on the feet are untreated, the foot tissue may die due to gangrene. Gangrene is a very serious condition where loss of blood supply leads to tissue death. It can lead to amputation. People with diabetes are especially at risk.
If a blood clot blocks an artery suddenly and completely, the leg quickly becomes painful, cold, numb, and blue in colour. There's usually no pulse felt below the blocked part of the artery. This is a medical emergency and you should seek immediate medical attention.
Making the Diagnosis
Your doctor may do some of the following tests if PAD is suspected:
- blood tests to measure cholesterol and sugar levels
- blood flow measurement using a device called a Doppler ultrasound
- magnetic resonance angiography (MRA) scans to see clots in the arteries
- angiograms or arteriographs to get a closer look at the damaged blood vessels
- blood pressure measurements in the ankle and arm (ankle brachial index or ABI)
Blood pressure tells the doctor how much blood is flowing to a certain area. To diagnose intermittent claudication, the doctor will see if the blood pressure in the ankle is 90% of the blood pressure in the arm.
If the pressure in the ankle is less than this figure, the doctor will suspect that the leg artery is blocked.
The Doppler ultrasound can pick up the sound of blood going through the artery. The sound of the blood flow indicates how badly the artery is blocked. The sound signal is then converted into a picture. A colour Doppler ultrasound can show different rates of blood flow.
During angiography, a dye solution that shows up on an X-ray is injected into the artery. X-rays are then taken to show the rate of blood flow and the diameter of the artery to see whether the artery is blocked. Doppler ultrasounds are used more often than angiography, as they are non-invasive and don't use X-ray radiation.
Treatment and Prevention
PAD does most of its damage during its "silent" stage, before the person is aware of having it. Even so, most doctors don't favour routine screening to find silent PAD, as it would cause many patients to undergo unnecessary invasive tests. However, people with health problems or lifestyles that could lead to PAD should be watched closely for any symptoms and then tested as needed.
If you show symptoms and are diagnosed with PAD, your doctor might recommend some lifestyle changes that can slow down its progress. This advice will include the following:
- Eat a healthy diet. Cut down on foods that contribute to high cholesterol and high blood pressure.
- Exercise. Take walks, take up gardening, or use the stairs instead of an elevator, for example. Exercise helps lower blood pressure, increases blood circulation, strengthens the arteries to improve blood flow, and can help you lose weight.
- Raise the head of your bed by four to six inches. This can also help improve blood flow to your legs.
- Stop smoking. Most people who stop smoking see improvement in their PAD symptoms.
- Take the medications prescribed for diseases that contribute to PAD. If you take medications to treat high blood pressure or high cholesterol, it's important to take them consistently and properly according to doctor and pharmacist instructions. For diabetics, maintaining good blood sugar control is vital in helping to ward off worsening PAD.
- Consume alcohol in moderation. Limit your alcohol consumption to no more than 2 drinks per day for men and no more than 1 drink per day for women.
It's crucial to slow down the progress of PAD in order to limit its complications. If your PAD continues and you need treatment, there are a few options, including medications and surgical procedures.
Medications used to treat PAD include acetylsalicylic acid (ASA)* and clopidogrel. These are blood thinners which help prevent PAD from worsening and also protect against heart attacks and strokes.
When arteries are blocked suddenly, it is usually because of a blood clot – in this case, intravenous blood thinners such as heparin can help improve blood flow in a hospital setting. Other medications such as pentoxifylline may make it easier for oxygen to get to the muscles.
An angioplasty can reopen blocked areas in the blood vessels. Your doctor inserts a catheter (a small tube) into the affected artery and inflates and deflates a small balloon repeatedly to widen the plaque.
Angioplasty can only be done if the artery hasn't yet hardened. The blockage also has to be over just a small area of the artery and there can't be too many blocked areas along the artery. During an angioplasty, you don't have to undergo general anesthesia, and so the hospital stay is about a day. Medications such as heparin or acetylsalicylic acid (ASA) are given after the procedure to prevent blood clots from forming.
A stent or a small metal frame can be inserted into the artery in order to support the artery walls after an angioplasty.
Bypass surgery might be necessary if other treatments don't work. The surgeon takes a bypass graft – a tube made of a synthetic material or a vein from another part of the body – and joins it to the artery above and below the obstruction. Another approach is to remove the blocked or narrowed section and insert a graft in its place. Sometimes, if the affected area is small enough, the doctor might be able to cut the clot out and save the artery.
PAD can cause severe complications in the legs and feet. Because there's less blood flowing to those parts of the body, the muscles and skin won't get the nutrients they need. A cut, scrape, blister, or any other type of damage to the skin may have a harder time healing. For this reason, it's very important to take extra care of your feet if you have PAD.
Here is some advice to identify and prevent PAD.
- Look at your feet every day, especially around the time of a bath or shower.
- Don't walk barefoot; it may cause small cuts or scrapes and promote infection in cuts that may already be present.
- Use mild soap to wash your feet.
- Dry your feet thoroughly after washing and don't use skin creams unless your doctor recommends them. Damp skin can break down easily and moisture can trigger bacterial growth, causing an infection.
- Cut your toenails very carefully and straight across. You want to avoid in-grown toenails.
- Wear comfortable shoes and watch carefully for blisters when you wear new shoes. If you notice any cuts, blisters, or other problems, monitor them closely. Ulcers should be covered with clean, dry dressings.
Be sure to contact your doctor if the cuts or ulcers don't seem to be healing, get redder or bigger, change colour, or develop a foul odour. Your doctor might prescribe an antibiotic in the form of an ointment or a pill. It can take weeks or months for the antibiotics to cure an infected ulcer.
In rare cases, if a leg or foot infection is severe or gangrene develops, amputation may be needed. But this is a last resort – most often, prompt and appropriate treatment is enough to prevent the infection from spreading.
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