DEAR MAYO CLINIC: I am in my early 50s, and I enjoy hiking and biking. I was active until leg pain brought me to my doctor. I was diagnosed with a blockage of the artery behind my right knee. What is this condition, and what treatments are available?

ANSWER: Your condition, called peripheral artery disease, is a common problem in which narrowed arteries reduce the amount of blood that reaches the limbs. The type of blocked artery you describe can be treated in several ways. The specific treatment you need depends on the severity of your symptoms and the extent of the blockage.

The most frequent cause of peripheral artery disease is a buildup of fat and calcium deposits on artery walls. Over time, this buildup, which is known as atherosclerosis or plaque, can limit blood flow through the artery and lead to serious problems, including tissue death and amputation of the affected limb.

When plaque begins to form, it doesn't cause symptoms. But it can be detected during a physical exam when blood pressure in an ankle or leg is compared to blood pressure in an arm. Normally, blood pressure is higher in the legs than in the arms. As a blockage develops, though, blood pressure in the leg falls.

Factors that increase risk for plaque buildup include cigarette smoking, diabetes, kidney failure, high blood pressure and high cholesterol.

If these factors are not controlled, plaque continues to build and symptoms begin to appear. The most common symptom, called "claudication," is leg pain or cramp with walking. Depending on how advanced the disease is, the pain may be mild or severe. As the disease progresses, the distance you can walk without pain gets shorter. The first approach to treat this disease is to take part in physical activity or a walking program for 30–40 minutes three to four times per week.

If nothing is done to treat the risk factors, peripheral artery disease can progress to its most serious stage, which is when blood flow to the limb is dramatically decreased. A telltale symptom of this stage is leg pain at resting, particularly at night when the leg is raised on a bed. Often patients must get out of bed or dangle their foot outside the bed to relieve symptoms.

Treatment varies based on the severity of the disease. When peripheral artery disease is diagnosed in the early stages of the disease, lifestyle changes often are enough to treat it. Quitting smoking; eating a healthier diet; and controlling high blood pressure, high cholesterol or diabetes — along with a daily walking program — can help. These steps typically slow or stop progression of the disease because they allow the body to develop other channels for blood to bypass the blockage. Exercise can help condition muscles to get oxygen from blood more efficiently, so the muscles can work better despite reduced blood flow.

If lifestyle changes are not enough to slow the disease's progress, or if severely limited blood flow threatens the viability of the leg, additional treatment may be necessary.

One treatment possibility is bypass surgery performed by a vascular surgery team. A blood vessel from another part of the body or an artificial blood vessel is placed around the blockage in the leg, so blood can flow around the affected artery.

A less invasive approach involves endovascular treatment, which includes options such as angioplasty, stents and plaque removal. In angioplasty, a small hollow tube, called a catheter, is threaded through a blood vessel to the blocked artery. A small balloon on the tip of the catheter is inflated to expand the artery, flatten the blockage and stretch the artery open to increase blood flow. A mesh metal framework, called a stent, may be placed in the artery to keep it open. Some catheters also can be used to remove plaque. The plaque buildup can be physically removed from the artery, either by scraping it out with a blade or drill, or using a laser to destroy it.

For a person in your situation, a conservative approach to treatment is usually an appropriate first step. Medical intervention typically is not necessary, unless peripheral artery disease has advanced to the point that the health of the limb is threatened.

My recommendation is to follow up with a vascular expert for a more thorough review of your situation to determine the best treatment for you. — Dr. Young Erben, Vascular Surgery, Mayo Clinic, Jacksonville, Florida

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