Peripheral Artery Disease
Peripheral artery disease (PAD) is also commonly referred to as the ischemic disease of the extremities. It is a frequent condition that is usually underestimated (by patients) with unpleasant consequences including amputations. Lower extremities are affected more often than the upper ones.
Peripheral artery disease is very similar to angina pectoris. Angina pectoris is a result of gradual narrowing of coronary arteries. In PAD, such narrowing occurs in arteries of the extremities, typically in arteries of the lower limbs (pelvic, femoral knee an infrapopliteal arteries). The condition is caused by a complex process known as atherosclerosis. The atherosclerosis, very simply put, is a gradual fat deposition in the walls of arteries, which leads to their narrowing. Narrowed arteries are unable to deliver enough oxygen into target tissues, typically during physical exercise. The risk factors for PAD are the same as risk factors for atherosclerosis - smoking, diabetes, high blood pressure and high cholesterol.
The disease has a gradual course, we distinguish four main stages.
In the first stage, the condition is asymptomatic as the arteries are only slightly narrowed and the oxygen supply for the affected limb is still adequate.
The narrowing of the arteries progresses to a stage where the affected limb does not get enough oxygen during physical exercise. This leads to ischemia and ischemia usually hurts. PAD causes a typical leg pain known as claudication. Such claudication occurs during walk and quickly withdraws at rest. We speak about the “claudication distance”, which is the distance the patient is able to walk until being forced to stop because of the pain. If untreated, the claudication distance gets shorter.
The condition worsens and the patient suffers from pain not only during physical exercise, but usually even at rest. The narrowed arteries already fail to deliver enough oxygen even without a load.
The fourth stage of the disease is also known as the “critical limb ischemia”. In addition to the pain rest, the limb exhibits sign of a chronic severe lack of oxygen. The tissues succumb to necrosis, healing of wounds is impaired and there is increased risk of infections that can threaten the limb (risk of gangrene).
The doctor is especially interested in information about claudications, i.e. leg pain dependent on physical exercise. Physical examination is targeted on pulse check, usually in both groins, in popliteal area and in ankles. Impalpable pulse is typical for severe narrowing or total closure of arteries. It is advisable to also check the ankle pressures to more precisely estimate the severity of condition.
The length of the claudication distance can be measured by walking on a treadmill. The arteries and the blood flow are well-examinable by an ultrasound. The most accurate examination is angiography when the doctors apply a contrast agent into the arterial system and watch its flow through local limb arteries..
A sudden arterial occlusion is probably the most feared acute complication of PAD. The situation is basically similar to a heart attack. In an artery damaged by atherosclerosis, a blood clot may occur that suddenly closes the whole arterial lumen and the limb looses all the blood supply. This condition manifests with a sudden and very strong leg pain that does not fade at rest. The limb gets cold and there is no palpable pulse under the area of arterial closure. This is clearly an emergency condition, the patient must be hospitalized and the closure solved (by an endovascular or surgical intervention). Without emergent treatment, the limb dies and must be amputated.
Early stages of the disease can be treated conservatively. The patient should regularly use some anti-coagulation drugs and drugs against high cholesterol, especially statins. Vasodilatation drugs also have some effects. The more invasive approach is either endovascular or surgical. Endovascular approach consists of a therapeutic angiography where the narrowed area is dilated by a special balloon (angioplasty) and secured by a stent. A vascular-surgical procedure is done by creating a bypass bridging the narrowed location. Such bypass is usually made of a peripheral vein. Advanced stages of the disease with complications must be sometimes solved by an amputation of necrotic tissue.