So worried about loss of limb is the most feared complication of PAD that it was rated as equally or more serious than death by 38% of respondents in a survey of patients with intermittent claudication. Although progress has been made in the treatment of atherosclerosis in the coronary and cerebral vasculature, there has been little impact in its management of treatment in the peripheral arteries. This is at least in part due to the fact that the manifestations of disease are more diverse and often involve multilevel occlusive and limited segment lesions.
In this context, atherosclerosis is a major cause of morbidity and mortality through the reduced or loss of mobility that it causes, often in conjunction with the effect of coronary and cerebral vascular disease. Approximately one third of patients are affected in terms of intermittent claudication, which has a significant impact on quality of life. In its most severe form, critical limb ischemia, it can lead to amputation and is associated with a substantial risk of cardiovascular death.
Atherosclerosis is a condition where the arteries become narrowed and hardened due to an excessive build-up of plaque around the artery wall. The disease is not only confined to arteries within the heart and brain but also affects the abdominal aorta, the arteries in the upper and lower limbs.
What is Peripheral Arterial Disease?
Symptoms can range from none to severe and crippling. The most known symptom of PAD is “intermittent claudication”. This is pain in the limbs that occurs with exercise and is relieved by rest. It is due to the muscles not getting enough blood and oxygen. Atheroma can also ulcerate or become infected, particularly if the blood supply is poor. Pain at rest and the presence of non-healing wounds is a severe and advanced form of ischemia. If chronic ischemia is sustained, muscle atrophy can occur and in severe cases, there can be tissue necrosis. In the very worst cases, this can lead to amputation of limbs.
PAD is a common and potentially serious disease. It is a common site of atherosclerosis secondary to the lower limbs being relatively hypoperfused. It is an indicator of a systemic atherosclerotic disorder and perhaps a presage of widespread arterial disease, e.g. cerebrovascular or coronary. While asymptomatic PAD certainly matters, it is the symptomatic patient who presents a real opportunity for both secondary prevention of cardiovascular events and improvement in quality of life through restoration of blood flow to ischemic limbs.
What is peripheral arterial disease (PAD)? It is the build-up of plaque in the arteries that carry blood to the head, organs, and limbs. Plaque is made up of fat, cholesterol, calcium, fibrous tissue, and other substances in the blood. When arteries become clogged with plaque, blood does not flow as efficiently to the organs and limbs. Over time, it can harden and narrow the arteries so that organs and limbs do not receive an adequate blood supply. This can result in damage to organs and limbs. PAD is a serious disease and is a sign of widespread deposits in the blood vessels. People with PAD have a 6-7 fold increase in mortality over 10 years and a significantly decreased quality of life.
Importance of Preventing Peripheral Arterial Disease
Preventing PAD is very important. The symptoms of PAD and its treatments can often be inconvenient and painful, and at times associated with serious health complications. The most concerning potential complication caused by PAD is Critical Limb Ischaemia (CLI). CLI is a severe blockage in the arteries of the lower extremities, which markedly reduces blood flow. CLI can be characterized by non-healing wounds. Due to the poor circulation, cuts or sores on the feet can take a long time to heal, if at all. This is because the blood is not transporting the required nutrients and immune cells to the site of the injury. The natural healing process will not take place if the immune response is hindered. If the circulation is not improved, the wound will begin to deteriorate into an ulcer. This can become a very serious problem, since ulcers can get infected and infected ulcers can result in amputation. In fact, CLI is the leading cause of amputation for the lower extremities, and for 1 in 4 patients with CLI, the end result will be amputation.
Lifestyle Changes to Prevent Peripheral Arterial Disease
Regular exercise can actually stop the pain in your legs, the progression of Peripheral Artery Disease (P.A.D.), and improve your functional performance, research shows. The theory is that exercise increases the distance that a person with P.A.D. can walk without pain. In the long run, the goal is to help people with P.A.D. walk long enough and far enough to get regular exercise, which will further improve their walking performance. If you have P.A.D., a supervised exercise program may be the best way to rehabilitate your walking ability. In a supervised exercise program, your walking is monitored while you are exercising on a treadmill. Supervised exercise has been shown to be more effective than unsupervised exercise for increasing pain-free walking and total walking distance. If supervised exercise is not a viable option, studies have shown that home-based walking exercise can also be effective for people with P.A.D.
2.1. Regular Exercise
Regular exercise is a pivotal lifestyle change to prevent the onset of peripheral arterial disease. The reason is the direct effect exercise has on PAD risk factors. Regular exercise can assist in lowering high blood pressure, cholesterol, and help aid in weight loss for those who are overweight. It is understandable that for people with no symptoms of PAD, walking is a good form of exercise. A recommended schedule is walking 30-60 minutes a day, most days of the week. This is one of the best ways to improve symptoms and reduce the risk of PAD for those who are currently suffering. Regular exercise has been shown to be the best way to increase walking distance and improve overall physical function for those with intermittent claudication. For those with this symptom, supervised exercise programs have a very high success rate in which a program typically lasting 3 months is designed to help increase walking ability on a treadmill and time spent on a leg exercise ergometer. Overall, exercise is a very effective and efficient way to prevent PAD and improve symptoms if done regularly.
2.2. Healthy Diet
A healthy diet has been shown to directly reduce the risk of developing peripheral arterial disease. A well-structured diet reduces high blood pressure and cholesterol levels, two major risk factors in PAD. The first step in preventing PAD is to stop consuming high cholesterol and high fat foods. Saturated fats are considered solid fats, as opposed to liquid vegetable oils. Found mainly in animal products such as red meat, milk, and eggs, these fats raise blood cholesterol. High cholesterol foods include pastries, pies, and cookies; animal fats; processed meat and sausages. Consider decreasing the use of butter and opt for a margarine with no trans fats. Read food labels and try to eliminate and avoid foods high in these fats. Fast food and deep-fried foods are directly related to the development of PAD given their high fat content. These fats can build up on artery walls and constrict or block blood flow to the legs and toes, which can create PAD symptoms. By staying away from these types of foods, you can immediately decrease the risk of developing the disease. High cholesterol and fats are also found in packaged or processed foods. Try to substitute these with more fruits and vegetables. Instead of a snack food, eat an apple or some carrots. This is an overall way to increase the amount of necessary vitamins and minerals that can have great effects on the overall health of the body and increase disease prevention.
2.3. Smoking Cessation
Smoking adversely affects all factors that can lead to peripheral arterial disease (PAD), and the importance of cessation cannot be overemphasized. “The relative risk of claudication is increased by 10.5 times in males and 5.5 times in females who smoke compared with those who have never smoked”. Stopping smoking causes an immediate fall in risk and within a few years, the risk approaches that of nonsmokers. The longer the duration and the greater the number of cigarettes smoked, the higher the risk of developing PAD. Epidemiological studies have shown a dose-dependent increase in risk among current and former smokers compared with persons who have never smoked a cigarette. Cessation is known to have a beneficial effect, and help is available for patients who wish to stop. A systematic review has shown that smoking cessation interventions in patients with intermittent claudication are effective. This has been confirmed in a recent randomized controlled trial on the efficacy of physician advice to quit smoking compared with brief smoking cessation counseling. Treatment for tobacco dependence resulted in a significant increase in long-term abstinence (30.1% vs. 18.3%). Maintenance of cessation is important, and it has been shown that smokers with a past history of intermittent claudication have a tendency to be heavier smokers than those without a history. With advice and support from healthcare professionals and the use of behavioral and pharmacological treatments, cessation can be achieved and maintained.
3. Risk Factors for Peripheral Arterial Disease
The disease involves a narrowing of the arteries other than those that supply the heart, and as poorly controlled high blood pressure, diabetes, high cholesterol, and obesity are risk factors for developing atherosclerosis. It is these diseases that cause damage to the arteries throughout the body, increasing the risk of developing peripheral arterial disease. Older people have a higher risk of the disease. It is also possible that genetic factors play a part in the disease’s development, but more research is needed to support this. Women are more likely to develop peripheral arterial disease than men, which contrasts with coronary artery disease. This is likely due to the fact that women live longer than men, and peripheral arterial disease becomes more common as one grows older. It is also possible that hormone factors and a tendency for women to have smaller, more distal vessels than men may also be predisposing factors for the disease. The role of hormone replacement therapy and its effect on the risk of peripheral arterial disease is unknown. High blood pressure is a significant risk factor for peripheral arterial disease. In a recent analysis of the Framingham heart study data, blood pressure was found to be the most important modifiable risk factor for claudication, and an increase in systolic blood pressure of 20 mm Hg was shown to double the risk of claudication. High cholesterol levels have clearly been shown to be a risk factor for the development of atherosclerotic diseases. The arterial lesion in peripheral arterial disease is essentially the same as that in coronary artery disease, and high cholesterol levels have been shown to be a risk factor for the development of claudication and the requirement for revascularization procedures. It was previously thought that diabetes was a risk factor only for the microvascular sequelae of peripheral arterial disease and not a risk factor for the macrovascular disease that is the disease of the larger arteries. However, it is now known that diabetes is a significant independent risk factor for the development of peripheral arterial disease, and patients with diabetes have a two to four-fold increase in the risk of developing peripheral arterial disease. Obesity is a strong risk factor for peripheral arterial disease, and as a modifiable factor, it can be an important target in efforts for prevention of the disease. In a 12-year follow-up study of health professionals in the United States, there was a significant association between increasing BMI and the development of symptomatic peripheral arterial disease in both men and women, with the risk of developing the disease being three times higher in men with a BMI of 29-30.9 kg/m² and seven times higher in men with a BMI of greater than 31 kg/m², with similar results for women.
3.1. Age and Gender
The prevalence of PAD has been reported to increase exponentially with age. The disease affects 1 in 20 Americans over the age of 50 and 1 in 5 Americans over the age of 65. Sixty to eighty percent of individuals with PAD are asymptomatic. There is a higher prevalence of PAD in older age and in patients of African American ethnicity. The disease is more common in men than women. In the Rotterdam study of 7,983 subjects over the age of 55, 6.3% of men and 3.6% of women were found to have PAD. Age provides the strongest epidemiological link with PAD. Though some have argued that the association between age and PAD is skewed because the elderly are more likely to present with atypical symptoms, there is sufficient evidence to suggest that the disease is more than simply a manifestation of aging. During the Edinburgh Artery Study, the age and sex-adjusted incidence of intermittent claudication at a 5-year follow-up was reported to be 3.23 per 1000 person years. This rate doubled when a history of cardiovascular disease or an abnormal cardiovascular risk factor was present. This study considered the incidence of only symptomatic disease, and therefore the true impact of PAD as a marker for systemic atherothrombosis and cardiovascular disease is much greater. Although more commonly a disease of the elderly, 25% of patients diagnosed with PAD are under the age of 50. This generally represents a group with a premature atherothrombotic phenotype, and in the absence of intervention, a progressive deterioration to more severe disease. PAD, however, remains both underdiagnosed and undertreated in the elderly and in the general population.
3.2. High Blood Pressure
High blood pressure can be a result of other risk factors for PAD, such as obesity, high cholesterol, and diabetes. Changes to lifestyle focusing on reducing weight, taking regular exercise, and eating a healthy diet can help to lower blood pressure. If these changes are unsuccessful, doctors may recommend taking medication to reduce blood pressure. Any reduction of the level of blood pressure to normal or below will lower the risk of developing PAD.
High blood pressure, or hypertension, is a significant risk factor for PAD and many other medical conditions. Blood pressure is a measure of the force of the blood flow inside the blood vessels. Normal blood pressure is defined as less than 120 mmHg (systolic) and less than 80 mmHg (diastolic). Anything higher than 140/90 is considered to be high blood pressure. High blood pressure puts extra stress on blood vessel walls. Over time, this can make the vessels become less elastic, thicker, and narrower. If the blood vessels are narrowed to the arteries in the legs, it can cause pain on walking because of the reduced blood supply to the muscles.
3.3. High Cholesterol Levels
Cholesterol is an essential substance for the body; however, too much cholesterol in the blood can lead to atherosclerosis. Atherosclerosis is a gradual thickening and hardening of the arteries and can be a precursor to many problems such as PAD. The extra cholesterol from the blood is deposited in the walls of the blood vessels. This can cause the vessels to become narrowed or completely blocked. High cholesterol levels can lead to atherosclerosis in the peripheral arteries, reducing or completely blocking the blood flow to the legs. This can lead to pain while in motion and is a symptom of intermittent claudication. High cholesterol is also a risk factor for coronary artery disease. The coronary arteries are the blood vessels that supply the heart with oxygen and vital nutrients. Like PAD, atherosclerosis in the coronary arteries can cause restricted blood flow to the heart and lead to chest pain, heart disease, and if the vessel becomes completely blocked, a heart attack. High cholesterol is a controllable factor that can lead to many other health problems, thus it is better to take preventative action sooner rather than later.
3.4. Diabetes
Diabetes is associated with several metabolic abnormalities that may lead to PAD. Insulin resistance, which occurs in type II diabetes and uncontrolled type I diabetes, may increase the risk of PAD. Hyperglycemia has been implicated as a risk factor for cardiovascular disease, although its independent role in the development of PAD has not been clearly defined. There is also evidence to suggest that diabetes alters the natural history of PAD. The Framingham Study found that compared to non-diabetics, claudication in diabetics was associated with a wider range of functional impairment and a higher risk of developing critical limb ischemia. Ankle brachial index (ABI) is a marker for PAD severity and in diabetics with claudication, lower ABI values and a higher rate of ABI decline were demonstrated, indicating increased disease progression. Diabetics with PAD have a higher risk of adverse limb outcomes, including amputation and death. A recent study demonstrated that diabetics with intermittent claudication or abnormal ABI had a 4-year mortality rate of 36%, significantly higher than the 23% rate found in non-diabetics with PAD.
Patients with diabetes are 2-4 times more likely to develop peripheral arterial disease; this risk increases with age. Diabetes is an important risk factor because it may accelerate atherogenesis and the progression of PAD. Diabetics also have a higher prevalence of systemic hypertension and dyslipidemia than non-diabetics, and management of these conditions has not been shown to negate the increased risk of PAD associated with diabetes.
3.5. Obesity
The most powerful relationship between obesity and PAD appears to be via its association with systemic atherosclerosis. Obesity is a major independent risk factor for the development of atherosclerosis. This is closely linked to the metabolic abnormality that often accompanies obesity. Insulin resistance is associated with an atherogenic lipoprotein profile (elevated triglycerides and small dense LDL particles and low HDL cholesterol). These lipoprotein abnormalities and the systemic inflammation that obesity invokes accelerate the development of atherosclerosis and increase the risk of ischemic events. Abdominal obesity appears to have the strongest correlation with PAD. Data from the Multiple Risk Factor Intervention Trial (MRFIT) suggest that central adiposity confers an increased risk of leg ischemia independently of BMI. This may be due to the enhanced production of free fatty acids and cytokines from visceral fat, which have adverse effects on peripheral vascular endothelium.
Obesity is a complex health problem. It is a leading preventable cause of death worldwide, with increasing prevalence in adults, children, and the elderly. It is an important independent risk factor for several chronic diseases such as diabetes mellitus, cardiovascular disease, hypertension, and certain cancers. Recent studies have revealed that obesity is associated with a higher prevalence of peripheral arterial disease (PAD). Obesity may exacerbate the development of PAD through various mechanisms. These include its effects on systemic atherosclerosis, an increased incidence of other risk factors for PAD, and the potential for direct damage to the arteries of the lower limb.
