What is peripheral arterial disease?

Peripheral arterial disease (PAD) develops when atherosclerosis (hardening of the arteries) results in reduced blood flow to the legs or - less commonly - the arms. Due to the fact that this condition produces pain when walking and is commonly associated with smoking, the German language also refers to it as "smoker's leg" or "window shopper's disease". This is because people affected by the condition are forced to stop and rest at regular intervals while waiting for the pain to pass.

What are the main symptoms?

Depending on the severity of the condition, peripheral arterial disease is usually divided into four stages of severity. At stage I, the patient is still asymptomatic. As the disease progresses and the arteries become increasingly narrowed, the following symptoms may develop:

• Pain while walking, also referred to as "intermittent claudication" or limping.
• Rest pain in the lower limbs
• Gangrene and/or necrosis, e.g. in the feet

What are possible causes?

As with coronary heart disease and myocardial infarction (heart attack), peripheral arterial disease almost always occurs as a result of atherosclerosis, i.e. hardening of the artery walls. The disease tends to mainly affect the arteries in the pelvis and the legs. Important risk factors for atherosclerosis include:

• Smoking
• Diabetes
• High blood pressure
• Abnormalities in lipid metabolism

Diagnosis of peripheral arterial disease

When a patient presents with symptoms that are characteristic of peripheral arterial disease, diagnosis is usually relatively straightforward.

• Blood pressure measurements: The ankle-brachial index (ABI), a test that involves taking measurements from the arm and comparing them to measurements from the legs, can be used to quantify the degree of arterial narrowing present.
• In addition, ultrasound investigations can provide information on the extent of arterial deposits present, and on how well blood is flowing through the blood vessels.
• A type of CT or MRI scan, performed using contrast agents, allows the physician to clearly visualize the arteries.
• The catheter-based visualization of the arteries using contrast agents (angiography) is considered the gold standard in the diagnosis of PAD. This procedure allows visualization of even very small blood vessels. It is also used to guide the implantation of stents inside the narrowed sections of affected vessels.

Diagnosis

• Blood pressure measurements: A comparison of blood pressure measurements from the legs and the arms (ankle-brachial index) can help pinpoint the location of the stenosis (narrowing).
• Ultrasound scan: in addition to the above, an ultrasound scan can show stenotic areas, arterial deposits, and the flow of blood through the blood vessels.
• CT, MRI: computed tomography (CT) and magnetic resonance imaging (MRI) are excellent tools for visualizing the major blood vessels of the body.
• Angiography: this catheter-based technique, which uses dyes to make the blood vessels visible, remains the gold standard in diagnostic techniques. This is because it allows the physician to identify the exact location, as well as the severity, of areas of stenosis in any of the body's blood vessels, including the very small ones. Furthermore, this technique allows treatment to be initiated immediately, as part of the same procedure. As long as the affected vessel is easy to reach with a catheter, the physician can insert a stent to support the vessel walls.

Treatment for PAD by region (Fig. 2)

• Arm: prosthetic bypass graft from the carotid artery to the subclavian artery (in the arm) beyond the point of stenosis (carotid-subclavian bypass; carotid-axillary bypass) (Fig. 3).
• Pelvis: Y-shaped artificial prosthetic graft from the aorta to the iliac or femoral arteries (aorto-biiliac bypass, aorto-bifemoral bypass), or a one-sided bypass graft, using a straight artificial prosthetic graft from the aorta to the iliac artery (aorto-iliac bypass), or to the femoral artery (aorto-femoral bypass) (Fig. 3).
• Legs: groin - endarterectomy and patch angioplasty (Fig. 4)
• Thighs: femoro-popliteal I bypass using prosthetic graft (from femoral artery to popliteal artery above the knee) (Fig. 5).
• Calves: femoro-popliteal III bypass (from femoral artery to popliteal artery below the knee) using a vein graft or a combination of vein and prosthesis if only an insufficient length of vein is available (prosthesis above the knee, with vein graft reaching from there to beyond the knee: this is known as a composite graft) (Fig. 5). If only an insufficient length of vein is available, the bypass is performed using prostheses made from special kink-resistant material (known as ringed grafts)
• Lower calves: femoro-crural bypass (from the femoral artery to one or several arteries in the lower calf) (Fig. 6).
• Foot: from the femoral artery or the popliteal artery to one of the two pedal (foot) arteries (femoro-pedal bypass; popliteal-pedal bypass) (Fig. 6).

Specialist procedures in complex cases with stenosis (narrowing) affecting arteries at different levels:
Extra-anatomic bypass procedures: from the artery in the arm to one or both of the femoral arteries (axillo-femoral or axillo-bifemoral bypass) (Fig. 7). Crossover bypass from the iliac artery (pelvis) or the femoral artery on one side of the body to the femoral artery on the contralateral side (iliaco-femoral crossover bypass; femoro-femoral crossover bypass) (Fig. 8).