Atherosclerosis is caused by the buildup of fatty deposits known as plaque along the wall of arteries that results in narrowing. Although atherosclerosis can affect any artery in the body, the term peripheral arterial disease refers to atherosclerosis that obstructs the flow of blood to the legs. The clinical symptoms of the condition become apparent as the process becomes advanced. Intermittent claudication, cramping of the lower limbs with exercise that is relieved with rest, is the most common symptom. Untreated, these symptoms can progress to critical limb ischemia, which includes pain at rest and the formation of ulcerations. Peripheral arterial disease has several causes, or risk factors.
Smoking
Smoking is a confirmed risk factor for the development of peripheral arterial disease. Data from the Framingham Study, an ongoing cardiovascular study following residents from Framingham, Massachusetts, showed that 78 percent of patients with intermittent claudication were smokers. Similarly, data from the Edinburgh Artery Study, a population study of 1,592 males and females aged 55 to 74 years, demonstrated a threefold increased risk of developing peripheral arterial disease in smokers compared to non-smokers. Smoking is the most easily modified risk factor.
Diabetes Mellitus
Diabetes mellitus is a condition characterized by elevated levels of blood sugar resulting from either a decreased production of insulin by the pancreas or from a decreased response of the body to circulating insulin. Epidemiological evidence from both the Framingham Study and the Edinburgh Artery Study prove a twofold to fourfold increase in peripheral arterial disease in people with diabetes compared to people without. The extent of peripheral arterial disease also appears to correlate with the duration and severity of diabetes.
Cholesterol
The American Heart Association endorses a desirable total cholesterol level of less than 200 milligrams per deciliter, or mg/dL, of blood. High cholesterol is defined as 240 mg/dL and above and has been linked to the development of peripheral arterial disease. Data from the Framingham Study demonstrated a doubling in the incidence of intermittent claudication in people with a fasting total cholesterol level of greater than 270 mg/dL. In addition, data from the Edinburgh Artery Study showed that low HDL, high-density lipoprotein, levels were associated with intermittent claudication. There is evidence to suggest that the treatment of high cholesterol can decrease both the incidence and progression of peripheral arterial disease.
Hypertension
The American Heart Association defines normal blood pressure as less than 120/80, less than 120 systolic and less than 80 diastolic, for an adult older than 20 years. Numerous studies have demonstrated an association between high blood pressure and peripheral arterial disease. According to the U.S. Cardiovascular Health Study, 52 percent of patients with peripheral arterial disease also had coexisting hypertension. Likewise, the Framingham Study found a 2.5- to fourfold increase in peripheral arterial disease in people with high blood pressure.
Other Causes
Other factors are weakly correlated to the development of peripheral arterial disease. These include obesity, defined as body mass index greater than 30, increasing age older than 50 years, a family history of peripheral arterial disease, and the presence of certain inflammatory substances in the blood.
It is important to note that the vast majority of peripheral arterial disease risk factors can be reversed or effectively controlled with lifestyle modification in combination with timely medical care.
References
- "Circulation"; Intermittent claudication. Incidence in the Framingham Study; WB Kannel, et al; May, 1970
- "Annals of Epidemiology"; The health risks of smoking. The Framingham Study: 34 years of follow-up; KM Freund, et al; July, 1993
- "American Journal of Epidemiology"; Smoking, lipids, glucose intolerance and blood pressure as risk factors for peripheral atherosclerosis compared with ischemic heart disease in the Edinburgh Artery Study; FG Fowkes, et al; February, 1992
