PERIPHERAL ENDARTERECTOMY

A peripheral endarterectomy is the surgical removal of fatty deposits, called plaque, from the walls of arteries other than those of the heart and brain. The surgery is performed when plaque blocks an artery and obstructs the flow of blood and oxygen to other parts of the body, most commonly the legs but also the arms, kidneys, or intestines. The peripheral arteries most often treated with endarterectomy are those that supply the legs, especially the aortoiliac arteries in the pelvic area. Other arteries that may be treated with endarterectomy include the femoral arteries in the groin, the renal arteries that supply the kidneys, and the superior mesenteric arteries that supply the intestines.

Endarterectomy surgeries are performed to treat advanced peripheral arterial disease (PAD). PAD most often occurs as a result of atherosclerosis, a condition characterized by the gradual build up of fats, cholesterol, cellular waste, calcium, and other substances on the inner walls of large and medium-sized arteries. Plaque, the hardened, waxy substance that results from this build up, can cause narrowing (stenosis) of an artery and block the flow of blood and oxygen. Peripheral endarterectomies are performed to reopen blocked arteries and to restore blood flow in the body (revascularization), helping to prevent heart attack, stroke, the amputation of a limb, organ failure, or death.

Demographics
People who have been diagnosed with PAD caused by atherosclerosis are at high risk of arterial blockage (occlusion) and are candidates for peripheral endarterectomy. Occlusive arterial disease is found in 15 to 20% of men and women older than age 70. When found in people younger than 70, it occurs more often in men than in women, particularly in those who have ever smoked or who have diabetes. Women with PAD live longer than men with the same condition, which accounts for the equal incidence in older Americans. African-Americans have been shown to be at greater risk for arterial occlusion than other racial groups in the United States.

Description
PAD is a progressive occlusive disease of the arteries, common in older people who have ever smoked or who have diabetes. Although there are other forms of arterial disease that affect peripheral arteries (Buerger’s disease, Raynaud’s disease, and acrocyanosis), PAD in most people is caused by widespread artherosclerosis, the accumulation of plaque on the inner lining (endothelium) of the artery walls. Most commonly, occlusive PAD develops in the legs, including the femoral arteries that supply the thighs with blood or in the common iliac arteries, which are branches of the lower abdominal aorta that also supply the legs. The arteries that supply the shoulders and arms are less commonly affected. Branches of the aorta that deliver blood to the kidneys, the infrarenal aorta and renal arteries, can become narrowed as a result of artherosclerosis, but are only rarely blocked suddenly and completely, a condition requiring immediate surgery. Even more rare is blockage of the branches that supply the liver and spleen.

The development of atherosclerosis and PAD is influenced by heredity and also by lifestyle factors, such as dietary habits and levels of exercise.

The risk factors for atherosclerosis include:
• high levels of blood cholesterol and triglycerides
• high blood pressure
• cigarette smoking or exposure to tobacco smoke
• diabetes, types I and II
• obesity
• inactivity, lack of exercise
• family history of early cardiovascular disease

Just as coronary artery disease (CAD) can cause a heart attack when plaque blocks the arteries of the heart, or blockage in the carotid artery leading to the brain can cause a stroke, blockage of the peripheral arteries can create life-threatening conditions. When peripheral arteries have become narrowed by plaque accumulation (atheroma), the flow of oxygen-carrying blood to the arms, legs, or body organs will be interrupted, which can cause cell death from lack of oxygen (ischemia) and nutrition. Normal growth and cell repair cannot take place, which can lead to gangrene in the limbs and subsequent amputation. When blood flow is blocked to internal organs, such as the kidneys or intestines, the result of tissue death can be the shutdown of the affected organ system and systemic (whole body) poisoning from waste accumulation.

Death can result if emergency surgery is not performed to correct the blockage. In some cases, the body will attempt to change the flow of blood when a portion of an artery is blocked by plaque. Smaller arteries around the blockage will begin to take some of the blood flow. This adaptation of the body (collateral circulation) is one reason for a lack of symptoms in some people who actually have PAD.

Symptoms usually occur when the blockage is over 70% or when complete blockage occurs as a result of a piece of plaque breaking off and blocking the artery. Blockage in the legs, for example, will reduce or cut off circulation, causing painful cramping in the legs during walking (intermittent claudication) and pain in the feet during rest, especially during the night. When an artery gradually becomes narrowed by plaque, the symptoms are not as severe as when sudden, complete blockage occurs. Sudden blockage does not offer time for collateral vessels to develop and symptoms can be equally sudden and dramatic.

Possible symptoms of reduced blood flow in the most typically affected arteries include:
• Arteries of the arms and legs: Gradual blockage creates muscle aches and pain, cramping, and sensations of tiredness or numbness; sudden blockage may cause severe pain, coldness and numbness. A leg or arm may become blue (cyanotic) from lack of oxygen. No pulse will be felt. Paralysis may occur.

• Lower aorta, femoral artery, and common iliac arteries: Gradual narrowing causes intermittent claudication affecting the buttocks and thighs. Men may become impotent. Sudden blockage will cause both legs to become painful, pale, and cold. No pulse will be felt. Legs may become numb. The feet may become painful, infected, or even gangrenous when gradual or complete blockage limits or cuts off circulation

• Renal arteries: Gradual narrowing may produce no symptoms and no change in kidney function. Sudden, complete blockage may cause sudden pain in the side and bloody urine. This is an emergency situation.

• Superior mesenteric artery: Gradual narrowing causes steady, severe pain in the middle of the abdomen about 30 to 60 minutes after a meal. Nutrients are lost and weight loss is common. Sudden, complete blockage causes severe abdominal pain, vomiting, and the urge to move the bowels. Blood pressure falls, intestinal gangrene may develop, and the patient may go into shock. This is an emergency situation.

Sudden, complete occlusion of an artery can also happen when a clot (thrombus) forms in an already narrowed artery. Clot formation (thrombosis) can occur anywhere in the body and travel to a narrowed portion of an affected artery and become lodged (embolism), blocking blood flow. Clots can sometimes be dissolved with anticoagulant drug therapy. When this therapy is not effective or a life-threatening blockage occurs suddenly, clots can be surgically removed using thromboendarterectomy, a procedure similar to peripheral endarterectomy.

Early treatment for PAD may include medical treatment to reduce the underlying causes: lowering cholesterol, lowering blood pressure, stopping smoking, increasing exercise, and reducing the likelihood of clot formation.

Clot-dissolving drugs (thrombolytic drugs) may also be used to remove a clot medically rather than to perform surgery. When these measures are not effective, or an artery becomes completely blocked, peripheral endarterectomy may be performed to remove the blockage (see also angioplasty and peripheral vascular bypass surgery). Treatment of risk factors must continue, because surgery only corrects the immediate problem, not the underlying causes.

Peripheral endarterectomy works best in narrow areas like the leg where the artery can be easily accessed, or when there is complete blockage of an artery by an atheroma that is short in length. Endarterectomy does not work as well for smaller arteries lower in the leg or in the foot or arm. Drug therapy, angiography, stent placement, or surgical bypass may be used to treat blockages of the arteries in these areas.

Patients undergoing peripheral endarterectomy will typically be given general anesthesia. The surgery is an open surgical procedure in which a vascular surgeon makes a relatively large incision in the outer skin to access the obstructed artery being treated. In order to perform the surgery, the blood that normally flows through the artery must first be rerouted through a tube connecting the blood vessels below and above the surgical site. The surgeon will then cut the obstructed artery lengthwise and will use surgical tools to clean away the accumulation of plaque. The hard, waxy substance comes out fairly easily, sometimes in a single piece. The artery will then be sutured closed or patched with a piece of a vein, usually from the patient’s leg, to enlarge the repaired artery and prevent later narrowing from post-operative scarring. The entire procedure will take about one hour if there are no complications.