Peripheral arterial occlusive disease (pAVK)

Peripheral arterial occlusive disease (PAD) is a circulatory disorder of the arteries in the arms or legs. The cause is a pathological narrowing of the arteries, which prevents them from transporting sufficient blood. The colloquial name "shop window disease" (Claudicatio intermittens in Latin) is based on the phenomenon that those affected have to take frequent breaks when walking due to the painful circulatory disorder. Due to the frequent occurrence of the disease in smokers, it is also colloquially referred to as a "smoker's leg". Very severe forms of pAVK are called limb ischemia (ischemia means lack of blood supply). Arteriosclerosis is the cause of pAVK in about 95 percent of cases.

In Germany, about 15 to 20 percent of people over the age of 70 are affected by peripheral arterial occlusive disease. At younger ages, men are affected more frequently than women. Different vessel sections can be affected by pAVD - in most cases it is the femoral artery (artery of the thigh), but often the vessels of the pelvis and the lower leg are also affected. Not all sufferers notice the symptoms of the disease, as many people restrict their daily lives to such an extent that they do not notice the symptoms.

In addition, pAVD is often accompanied by other diseases. As it is very likely that not only the vessels of the arms and legs are affected by calcification, but also all other vessels of the body, the risk of coronary heart disease (e.g. myocardial infarction, angina pectoris) and stroke is increased in pAVD patients.

The main cause of peripheral arterial occlusive disease is arteriosclerosis. This is responsible for about 95 percent of cases.

Risk factors for the development of pAVK are:

• Smoking: Smokers are three times more likely to develop pAVDs than non-smokers. Since smokers are more likely than average to develop pAVD, the term "smoker's leg" is used colloquially.
• Hypertension (high blood pressure)
• Diabetes Mellitus (diabetes)
• Disturbances of the lipometabolism: increased cholesterol level in the blood

If one risk factor is present, this increases the likelihood of developing the disease by two and a half times. If two risk factors are present, the likelihood of disease increases fourfold.

Raynaud 's syndrome (a functional disorder of the vascular muscles) is a rare cause of pAVD. Very rarely, thrombangiitis obliterans (inflammation of the inner layer of the blood vessels) can also be the cause. In this case, small thrombi (blood clots) form in the affected vessels, inhibiting the blood flow. Thrombangiitis obliterans almost exclusively affects smokers under the age of 40. The vessel occlusions usually occur in the arteries of the hand, lower leg and toes.

Peripheral arterial occlusive disease (pAVD) often runs painless and symptom-free for a long time at the beginning (stage I). Initial symptoms are often not noticed - those affected often only consult a doctor when pain occurs when walking or at rest. The vascular disease is usually only noticed at a very late stage, as symptoms often only appear when the vascular constriction exceeds 90 percent. The reason for this is that the body forms collateral vessels (new vessels that bypass the constriction), through which the tissue can continue to be supplied with sufficient blood.

The severity of the symptoms depends on the location of the vessel occlusion. If, for example, the femoral artery is affected, the pain is felt mainly in the lower leg below. The pain occurs particularly during sporting activities or when walking, as the leg muscles have a greater need for oxygen (blood) here. The exertion pain forces sufferers to stop several times while walking - hence the colloquial name "shop window disease". As the disease progresses, the toes and feet become visibly cooler and insensitive.

The extent of the symptoms of pAVK can be divided into the following four stages (subdivision according to Fontaine-Ratschow):

• Stage 1: no complaints
• Stage 2a: Pain after a walking distance of more than 200 metres
• Stage 2b: Pain when walking less than 200 metres
• Stage 3: Pain at rest
• Stage 4: Additional tissue damage (necrosis, gangrene) due to the circulatory disorder

The point at which sufferers notice symptoms varies from person to person. Patients who also suffer from nerve damage due to diabetes mellitus (diabetic polyneuropathy) often experience hardly any discomfort even in advanced stages of pAVK due to impaired pain perception.

In the case of an acute arterial occlusion (sudden complete blockage of an artery) caused by an acute thrombosis or embolism, a strong local pain is caused in conjunction with a feeling of numbness and coldness of the skin. No pulse is palpable in the area after the vessel occlusion. Acute arterial occlusion is an emergency and must be treated immediately.

Taking a medical history often provides the attending physician with the first indications of peripheral arterial occlusive disease (pAVD). During the physical examination, skin changes of the extremities, calluses on the feet, nail deformations and hair loss in particular can be signs of pAVD. The following examinations are performed to make the diagnosis:

• Palpation of the extremity pulses: in the case of pAVD, the pulse on the legs or arms is only weakly palpable or not palpable at all.
• Feeling the skin temperature: The leg affected by pAVD is significantly cooler than the leg with normal blood supply.
• With the help of a stethoscope, it may be possible to detect flow noises above the narrowed vessel site.
• Doppler ultrasound: This ultrasound test can show the altered blood flow in the narrowed area.
• Ankle-brachial index: comparative blood pressure measurement of the legs and arms.
• Walking test: The patient walks on a treadmill at a standardized walking speed until pain occurs. The walking distance until the onset of symptoms is measured, which allows the stage of pAVK to be determined.
• Angiography: By administering contrast medium, the blood vessels and any constrictions can be made visible by means of various imaging procedures (e.g. X-ray).
• Blood test: This can reveal possible risk factors (e.g. elevated cholesterol levels).

After the diagnosis has been made, the neck and heart vessels are often examined for further constrictions. If these narrowings are detected and treated at an early stage, the risk of a heart attack or stroke can be reduced.

The basic pillar of therapy for peripheral arterial occlusive disease is the targeted treatment of the causes. For smokers, the most important measure is to stop smoking immediately. In general, the disease can be greatly improved by regular exercise, a balanced diet, normal blood pressure and blood lipid values in the normal range.

In the case of pAVK from stage 2, daily walking training is an important measure for improving the symptoms. First of all, the walking distance that can be covered until the onset of pain is determined - at least half of this distance should be covered several times a day from now on. In this way, the body is stimulated to form so-called collateral vessels. These are blood vessels that bypass the constriction in the artery and thus bridge it. However, daily walking training should not go so far as to cause pain.

Drug therapy

In addition to gait training, so-called platelet aggregation inhibitors are administered in the case of pAVK. These are drugs that inhibit the clumping of blood platelets and thus prevent the formation of blood clots. Acetylsalicylic acid (ASS) is the drug of choice. If there are intolerances to this substance, clopidogrel can be prescribed as an alternative in individual cases.

From stage 2 onwards, the use of other drugs may be recommended. So-called phosphodiesterase inhibitors (PDE inhibitors) counteract clumping of the blood platelets, which makes the blood thinner.

If the blood supply to the vessel cannot be restored by means of surgery, the therapy may be extended to include intravenous administration of so-called prostanoids . These agents cause the blood vessels to dilate and improve the flow properties of the erythrocytes (red blood cells), allowing the blood to pass more easily through the constricted blood vessels.

Surgical interventions

Another option for treating pAVD is to surgically repair the narrowing of the blood vessels. Whether or not surgery is performed depends on the stage of the disease and the location of the narrowing. Despite surgery, there is a risk that a new constriction will form in the affected vessel over time.

The following surgical measures can be performed as part of pAVK treatment:

• Angioplasty (vascular dilatation): this procedure is mainly performed for vascular stenoses in the area of the pelvic or femoral arteries. A balloon catheter is inserted through the inguinal artery to the narrowed vessel and inflated at high pressure. In many cases, the constriction can be reopened or widened in this way. If balloon dilatation is not possible due to a rigid constriction, a so-called thrombendarterectomy (peeling out of the deposits) can be performed. If necessary, the implantation of a stent (vascular support) is necessary to reduce the risk of a renewed vasoconstriction.
• Bypass surgery: If the vasoconstrictions affect large parts of the leg vessels, a bypass surgery may be useful. In this case, blood is diverted around the narrowed vessel site by means of a newly inserted vein or a tube made of Teflon.
• Amputation: If the blood flow is so restricted due to the narrowing of the vessel that parts of the limb die off, the affected limb (e.g. toes) must be amputated.

A good prognosis for peripheral arterial disease depends heavily on whether the triggering factors can be treated. Otherwise, the disease will progress over time. A healthy lifestyle with sufficient exercise, non-smoking, a balanced diet and, in the case of overweight, weight reduction will improve the prognosis.

Furthermore, the prognosis is better if the blood sugar, blood pressure and blood lipid values are within the normal range. If diseases such as high blood pressure or diabetes mellitus are present, these should be specifically treated.

In addition, many people with pAVK also have vasoconstrictions in the heart and neck vessels, which greatly increases the risk of coronary heart disease (myocardial infarction, angina pectoris) and stroke.

In some patients, amputation, for example of the toes, becomes necessary due to inadequate tissue perfusion. Complications are particularly common in patients who also suffer from diabetes.

Life expectancy is lower in people with peripheral arterial disease than in their peers without vascular disease.

To effectively minimize the risk of developing peripheral arterial disease, the risk factors listed under "Causes" should be identified and avoided. Since smoking is the greatest risk factor for pAVD, it is essential to strive for a smoke-free life. In addition, the following points should be observed:

• Eating a healthy, balanced diet that is low in fat and high in fruits and vegetables.
• Avoid saturated fats and trans fats. Saturated fatty acids are particularly found in animal fats, trans fats in deep-fried products such as potato chips or French fries.
• Keeping to your ideal weight - if you are overweight, even a small amount of weight loss will reduce your risk of developing PAOD.
• Regular exercise - particularly effective is the practice of an endurance sport.
• Diseases such as diabetes mellitus (diabetes), hypertension (high blood pressure) or hypercholesterolaemia (high cholesterol) should always be treated by a doctor.