Peripheral Artery Disease and Intermittent Claudication

Description

Alternative Names

Risk Factors

Between eight and 10 million American adults have peripheral artery disease (PAD). The prevalence ranges from 3% in young adults to between 12% and 29% in people over 65. (These numbers are expected to rise as the population ages.) Intermittent claudication occurs in about one-third to one-half of PAD patients.

Although it is commonly believed that PAD occurs more often in men than women, current research now indicates that both genders are equally susceptible.

People in northern regions tend to have a higher risk than those in southern areas. In one study, Caucasians had a higher risk for PAD than people from India or the people of African descent from the Caribbean. Such findings are counter to studies suggesting higher risks for heart disease in African Americans and for diabetes in populations from India.

Heart Disease Risk Factors

The major risk factors for heart disease and stroke are also the most important risk factors for PAD and intermittent claudication. (The combination of such conditions with PAD also produces a more severe form of the heart or circulatory disease.)

They include the following:

• Diabetes. People with type 2 diabetes have three to four times the normal risk for PAD and intermittent claudication. In fact, their risk for PAD is higher than their risk for coronary artery disease. They also tend to develop PAD at earlier ages and to have severe cases. Of note, patients with both diabetes and PAD are also at high risk for complications in the feet and ankles. For example, in one study, people with diabetes and intermittent claudication had a 30% chance of developing skin ulcers on their legs.
• Unhealthy cholesterol and lipid levels. The risk for PAD is increased by 10% with every 10 mg/dL increase in total cholesterol levels. The risk is also associated with low high-density lipoprotein (HDL, the so-called good cholesterol) and high triglyceride levels.
• Smoking. Smoking increases the risk for PAD by two to five times, with the danger being higher when other risk factors are present. And, in fact, one study reported that 90% of patients with PAD were current or former smokers and some experts believe it is a stronger risk factor for PAD than for heart disease.
• Hypertension. High blood pressure doubles the chances for PAD.

Blood pressure is the force applied against the walls of the arteries as the heart pumps blood through the body. The pressure is determined by the force and amount of blood pumped and the size and flexibility of the arteries.

• Family history of artery disease. Genetic factors are associated with specific lipid and cholesterol abnormalities, which in turn may increase the risk for PAD.
• Evidence of inflammation and damage in the arteries. Tests that report elevated levels of C-reactive protein are indicators of persistent inflammation in the arteries, which is now known to cause significant damage in blood vessels. High levels strongly predict future heart attacks in patients with existing heart disease, particularly unstable angina. Inflammatory damage is also now highly associated with PAD. In fact, patients with both PAD and heart disease tend to have significantly greater indicators of inflammation than those with heart disease alone.

Emerging or Possible Risk Factors

Homocysteine. Abnormally high blood levels of the amino acid homocysteine are strongly linked to an increased risk of heart disease, stroke, and peripheral artery disease. (Not all studies support a strong association, however. Some research suggests that the harmful effects of homocysteine may be more pronounced in men than in women.) Homocysteine may harm the lining of the arteries and reduce blood flow. Excessive levels occur with deficiencies of vitamins B6, B12, and folic acid.

Click the icon to see an image of vitamin B12 sources.

Click the icon to see an image of sources of folate.

Some experts believe that high levels of homocysteine are only indicators, not causes, of heart disease. However, studies are noting a strong association between this compound and heart disease. For example, a 2000 study reported that lower homocysteine levels after taking folic acid and vitamin B12 were associated with more open blood vessels and improved blood flow

Infectious Agents. Some microorganisms and viruses have been under suspicion for triggering inflammation and damage in the arteries that contributes to heart disease and peripheral artery disease.

The primary suspect has been Chlamydia pneumoniae (a non-bacterial organism that causes mild pneumonia in young adults). This is based on the following:

• High levels of antibodies against C. pneumoniae have been associated with a higher risk for heart events.
• C. pneumoniae has been detected in plaques in the arteries of patients with heart disease.
• In one study, treatment with antibiotics in patients with evidence of a previous C. pneumoniae infection appeared to reduce the plaques of peripheral artery disease. In any case, until better studies are conducted, experts do not recommend antibiotics to treat heart disease or PAD even in patients with evidence of C. pneumoniae.

It should be noted that many people have been infected with C. pneumoniae and some studies have found no evidence that it increases the risk for heart disease.

Other infectious organisms under investigation for triggering disease process in the blood vessels including the following:

• Bacteria that cause periodontal disease. Many studies have reported an association between periodontal disease and a higher risk for heart disease. It has also been associated with PAD.
• H. pylori (the bacteria responsible for peptic ulcers). This bacteria has been associated with both heart disease and PAD. However, because this bacteria occurs in the intestinal tract and has not been detected in arteries, it is not clear how this bacteria could affect blood vessels.

No clear association has been found with any of these, however.