More detailed description about peripheral arterial disease

The disease is very common. Its incidence moves together with the incidence of atherosclerosis. After the age of 55, up to 20% of the people in the developed Western world show signs of beginning peripheral arterial disease with changes observed in the vessels, but no symptoms yet. Men are more commonly affected between the 5th and 6th decade of life, while at later ages the incidence is similar in men and women. There are also national differences (nations enjoying mainly the Mediterranean diet with a high proportion of fish have a lower disease prevalence) as well as racial differences with the black race much more commonly affected than the white race.

Causes for disease development

The most common cause for the appearance of peripheral arterial disease is atherosclerosis. Accumulation of lipids in the vessel wall causes the vessel lumen to narrow, thereby increasing the resistance which in turn means that less and less oxygen-rich blood reaches the lower parts of the lower extremities. Ischemia (Greek: without blood) appears. The lack of oxygen causes injuries in other tissues as well, such as the muscles and the nerves. The ultimate consequence is a gangrene (or tissue decay) which necessitates leg amputation.

Risk factors for the appearance of this disease are multiple and most often connected with atherosclerosis. The most severe risk factor is diabetes mellitus which increases the risk of developing peripheral arterial disease by 5-fold compared with the rest of the population. The remaining risk factors include smoking, increased body weight (body mass index (BMI) over 30), hypertension (above 140/90 mmHg), increased serum cholesterol levels as well as the age and sex. There is a genetic background to this disease. It is well-established that relatives of the patients present with this disease at an earlier age and more often compared to the rest of the population.

Symptoms

The signs and symptoms of disease start becoming apparent when the vessel lumen narrows by more than 50%. When critical narrowing is attained, characteristic crampy pain in the lower extremity develops (i.e. intermittent claudication). The exact location of the pain depends on the location of the occlusion; most commonly, the pain appears in the calf area and during increased physical activity (such as long-distance walking in elderly patients). The pain disappears upon a few minutes of rest and the patient is able to resume the walk. Other symptoms of disease include weakness in the extremities, feeling of cold, changes in the colour and hairiness of the skin, nail changes as well as poor-healing ulcers.

Diagnosis

Good diagnostic procedure begins with a careful study of the history of the present complaint as well as a thorough physical exam. The physician will most probably rapidly recognize the patient's "cramps" as intermittent claudication, but will likely order tests to confirm the diagnosis. The most important test is the so called ankle-brachial index which indicates the ratio between the blood pressure of the lower extremities (leg) and that of the upper extremities (arm). The smaller the index, the poorer is the blood circulation in the legs. Supplemental diagnostic examination procedures include an ultrasound of the vessels and angiography (i.e. vessel imaging with the use of a contrast dye).

Prevention

The aim of prevention is mainly to slow down the progression or the formation of atherosclerotic changes in the arterial walls. These changes take the form of aggregates of fat, inflammatory cells and calcium in the vessel walls which results in vessel narrowing. Many risk factors, such as sex, age and genetic factors, cannot be influenced.

There is, however, much one can do for oneself, including smoking cessation, maintenance of a normal body weight, regular physical activity, healthy low-fat nutrition as well as regulation of blood pressure, diabetes mellitus and blood cholesterol level (initially with a diet and, if unsuccessful, later with medication).

Therapy

Has two main goals:

To prevent the disease progression, thereby not only reducing the problems in the lower extremities, but also, and most importantly, reducing the risk of a heart attack or a stroke. A change from an unhealthy to a healthy lifestyle is undoubtedly an important part of not only prevention but also therapy. Additionally, medication for cholesterol level lowering (statins) as well as anti-hypertensive medications (diuretics, ACE inhibitors, beta-blockers and the like) are employed. If present, diabetes mellitus should be regulated as well. Aspirin is taken at the right dose to inhibit platelet aggregation whereby blood clotting is prevented at the sites of vessel damage and critical narrowing.

Symptom control such as pain in the lower extremities, especially in the calf area. If vessel narrowing is found with diagnostic imagining techniques, such as the ultrasound or the contrast-enhanced X-ray vessel imaging, there are several treatment options available.

Treatment options

The non-pharmacological treatment option focuses on interval muscle exercise. This is the modality of choice in people who have intermittent calf pain, and can actually increase the distance that a patient can walk pain-free for as much as 150%. The exercise regimen consists of alternating the intervals of walking at an individually-tailored pace to elicit moderate pain in 3-5 minutes with intervals of rest when the pain totally disappears.
When the segments of vessel narrowing or blockage measure only a few centimetres, it is possible to dilate them under x-ray imaging. To that effect, a balloon catheter is inserted to the site of the narrowing and inflated. If narrowing re-occurs, the procedure must be repeated and a stent placed at the critical site. Upon balloon inflation, the stent keeps the vessel patent.
If, however, the segments of vessel blockage are long, or if calcium has already accumulated in them and a catheter cannot dilate them, surgery may be performed. Using a vein that is harvested from another lower extremity site, a bypass is created to avoid the blocked area and re-establish arterial blood flow to that extremity. If blood flow can no longer be established and the lower extremity is no longer vital, it is necessary to resort to amputation.

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