Peripheral arterial disease (PAD)
The most common cause of PAD is atherosclerosis (see cardiovascular risk factors). People with one or more cardiovascular risk factors have a greater chance of contracting PAD. Main cardiovascular risk factors are smoking, diabetes, hypertension, hypercholesterolemia, overweight, and lack of physical activity.
What does PAD mean?
PAD means that the atherosclerosis process affects the blood vessels that bring blood to the legs (these vessels are called arteries). When this condition occurs , plaques inside the arteries will progressively narrow and finally block the blood flow. When the narrowing (also called stenosis) of the arteries becomes important (that means at least 50 %), symptoms can occur because the muscles do not receive enough blood.
What are the symptoms of PAD?
Claudication, which means « to limp », is the most common symptom of PAD. Claudication is defined as a pain (usually a cramp) or discomfort in the muscles of the legs (calves, feet), thighs, buttocks, or feet, that is worsened by exercise (generally walking) and relieved in a few minutes with rest (stop walking). The severity of claudication varies individually and depends upon how many arteries are affected, how narrow they are, what the speed of walking is, and whether the walk is on the flat or slope (uphill or down stairs etc).
Calf pain (calf claudication) is the most common complaint and is usually due do the narrowing or obstruction of either the main artery in the thigh (the superficial femoral artery) or the artery behind the knee (the popliteal artery).
Foot claudication may occur from narrowing or obstruction of an artery in the lower part of the leg (the tibial or peroneal arteries).
Thigh claudication may be due to narrowing or obstruction of the superficial femoral artery in the upper thigh or of the artery in the groin (the common femoral artery) or of the arteries above the groin (the commune and external iliac arteries).
Buttock claudication (that can sometimes mimic hip arthrosis) may be caused by a blockage of the commune iliac arteries or of the aorta (the main artery in the abdomen).
Other symptoms of PAD include loss of muscle mass and hair loss on the lower legs, and erectile dysfuction (when the aorta or iliac arteries are blocked).
A number of patients with claudication (about 20 %) will worsen, generally because the cardiovascular risk factors are not well supported. These patients may develop rest pain (onset of muscle cramps in the legs at night which are calmed by getting up and walking a little) and finally gangrene (tissue death because the arteries are too clogged and blood cannot arrive).
How to diagnose PAD?
The diagnosis of claudication is based upon the symptoms described above. Noninvasive tests can be performed to confirm the diagnosis and estimate the severity of PAD.
The ankle-brachial index (ABI) is the basic test to be carried out systematically when PAD is suspected. By means of a Doppler device, the ABI measures the resting blood pressure at the ankle compared with the blood pressure in the arm. A normal value is between 0.9 and 1.3. The test may be repeated after exercise (treadmill or walking up and down a stepladder).
Ultrasonography can be used to see the location and severity of the narrowing and obstruction in the arteries.
Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are other noninvasive ways of looking at arteries. They show more detail and are more expansive. These tests are usually used only if a revascularization (surgery or percutaneous angioplasty and stenting) is considered.
Arteriography, which is an invasive test, might also be considered.
How to treat PAD?
The treatment of claudication is based on medical therapy with or without some form of revascularization. Most people with claudication can be treated medically, which includes reducing cardiovascular risk factors, exercise training and using some medications that may improve walking distance. Despite an appropriate medical approach, some patients may remain with incapacitating claudication. These patients may be candidates for revascularization procedures, which include percutaneous angioplasty and stenting of the narrowed or blocked arteries, or a surgical procedure that opens or bypasses the blockage.
Cardiovascular risk factors
To help treat PAD and prevent it from getting worse, it is essential to try to stop smoking, to get diabetes, hypertension, and hypercholesterolemia under control, and to exercise daily.
Antiplatelet agents (medication that reduces blood clotting in arteries) are recommended for all patients with PAD. These medications modestly improve claudication and reduce the need for surgery and decrease the risk of heart attack (myocardial infarction), stroke, or death from PAD. Aspirin (81 to 325mg/day) is the most common accepted antiplatelet agent for patients with PAD. Clopidogrel (75 mg/day) could be an alternative in case of contra-indication or intolerance to aspirin.
Naftidrofluryl helps claudicants to increase their maximal walking distance compared with placebo. It is commonly used in Europe.
Cilostazol is the most effective treatment for claudication, particularly when combined with exercise. However this medication is not available everywhere in Europe and is contra-indicated in patients with heart failure.
Exercise programs increase the walking distance before developing symptoms of claudication. Best outcomes occur when patients are supervised. Improvement can be expected within three to six months and benefits will unfortunately diminish when exercise training stops. Effective supervised exercise training involves walking on a treadmill or a track for 45 to 60 minutes at least three times a week.
In selected cases, particularly if medical treatment has been unsuccessful, a revascularization (procedure to increase the amount of blood flow to the extremities) may be recommended. Revascularization procedures can be generally divided in two major categories : endovascular procedures , such as balloon angioplasty with or without stenting or surgery , such as bypass or thromboendarterectomy. There is no « standardized » revascularization procedure for claudication and each case should be discussed on the basis of a multidisciplinary approach (discussion between the vascular physician/angiologist, the vascular surgeon and the interventional radiologist).
Endovascular procedures are performed under local anaesthesia through a catheter placed in the groin region in the femoral artery. During these procedures, a thin tube with a deflated balloon at the end is sent to the part of the artery that is blocked . Then the balloon is inflated to open the blockage (this is called percutaneous balloon angioplasty or PTA). A stent is often used to keep the artery open after angioplasty. A stent is an expandable tube made of wire mesh and its goal is to prevent restenosis (= new narrowing of the artery). Unfortunately restenosis is unpredictable but the more all adequate medications are given, the more cardiovascular risk factors are well supported and the more the risk of recurrence is decreased.
Surgery usually involves sewing a graft to go around (bypass) the narrowed or blocked area of the artery, which improves blood flow to the rest of the leg. The graft is usually a piece of vein from an other part of the body, but sometimes man-made material. Thromboendarterectomy is the local removing of the plaques that block the passage of blood.