Online Medicine Resource: CAROTID ENDARTERECTOMY

What is a carotid endarterectomy?

A carotid endarterectomy is a surgical procedure in which a doctor removes fatty deposits blocking one of the two carotid arteries, the main supply of blood for the brain. Carotid artery problems become more common as people age. The disease process that causes the buildup of fat and other material inside the artery walls is called atherosclerosis, popularly known as "hardening of the arteries." The fatty deposit is called plaque; the narrowing of the artery is called stenosis. The degree of stenosis is usually expressed as a percentage of the normal diameter of the opening.

Why is surgery performed?

Carotid endarterectomy is performed to prevent stroke. Two large clinical trials supported by the National Institute of Neurological Disorders and Stroke (NINDS) have identified specific individuals for whom the surgery is beneficial when performed by surgeons and in institutions that can match the standards set in those studies. The surgery has been found highly beneficial for persons who have already had a stroke or experienced the symptoms of a stroke and have a severe stenosis of 70 to 99 percent. In this group, surgery reduces the estimated 2-year risk of stroke or death by more than 80 percent, from greater than 1 in 4 to less than 1 in 10.

For patients who have already had transient or mild stroke symptoms due to moderate carotid stenosis (50 to 69 percent), surgery reduces the 5-year risk of stroke or death by 6.5 percent. The failure rate for ipsilateral stroke or death for the medical group is 22.2 percent, and for the surgery group is 15.7 percent from greater than 1 in 4 to less than 1 in 7. Individuals who have already had stroke symptoms, and who have carotid stenosis greater than 50 percent, may wish to consider surgery to prevent future stroke. With the completion of the NASCET trial, patients with moderate (50 to 69 percent) stenosis will be better able to make more informed decisions.

In another trial, the procedure has also been found highly beneficial for persons who are symptom-free but have a carotid stenosis of 60 to 99 percent. In this group, the surgery reduces the estimated 5-year risk of stroke by more than one-half, from about 1 in 10 to less than 1 in 20.

What is a stroke?

A stroke occurs when blood flow is cut off from part of the brain. In the same way that a person suffering a loss of blood to the heart can be said to be having a "heart attack," a person with a loss of blood to the brain can be said to be having a "brain attack." There are two kinds of stroke, hemorrhagic and ischemic. Hemorrhagic strokes are caused by bleeding within the brain. Ischemic strokes, which are far more common, are caused by a blockage of blood flow in an artery in the head or neck leading to the brain. Some ischemic strokes are due to stenosis, or narrowing of arteries due to the build up of plaque, fatty deposits and blood clots along the artery wall. A vascular disease that can cause stenosis is atherosclerosis, in which deposits of plaque build-up along the inner wall of large and medium-sized arteries, decreasing blood flow. Atherosclerosis in the carotid arteries, two large arteries in the neck that carry blood to the brain, is a major risk factor for ischemic stroke.

What are the symptoms of a stroke?

Symptoms of stroke include:

Sudden numbness, weakness, or paralysis of face, arm or leg, especially on one side of the body.
Sudden confusion, trouble talking or understanding speech.
Sudden trouble seeing in one or both eyes.
Sudden trouble walking, loss of balance, or coordination.
Sudden severe headache with no known cause (often described as the worst headache in a person's life).

Symptoms may last a few moments and then disappear. When they disappear within 24 hours or less, they are called a transient ischemic attacks (TIA).

How important is a blockage as a cause of stroke?

A blockage of a blood vessel is the most frequent cause of stroke and is responsible for about 80 percent of the approximately 700,000 strokes in the United States each year. With nearly 150,000 stroke deaths each year, stroke ranks as the third leading killer in the United States after heart disease and cancer. Stroke is the leading cause of adult disability in the United States with 2 million of the 3 million Americans who have survived a stroke sustaining some permanent disability. The overall cost of stroke to the nation is $40 billion a year.

How many carotid endarterectomies are performed each year?

In 1995, the most recent year for which statistics are available from the National Hospital Discharge Survey, there were about 132,000 carotid endarterectomies performed in the United States. The procedure was first described in the mid-1950s. It began to be used increasingly as a stroke prevention measure in the 1960s and 1970s. Its use peaked in the mid-1980s when more than 100,000 operations were performed each year. At that time, several authorities began to question the trend and the risk-benefit ratio for some groups, and the use of the procedure dropped precipitously. The NINDS-supported North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the NINDS-supported Asymptomatic Carotid Atherosclerosis Study (ACAS) were launched in the mid-1980s to identify the specific groups of people with carotid artery disease who would clearly benefit from the procedure.

What are the risk factors and how risky is the surgery?

Important risk factors in addition to the degree of stenosis include, gender, diabetes, the type of stroke symptoms, and blockage of the carotid artery on the opposite side. Without other complicating illnesses, age alone is not a worrisome risk factor. Risk factors can affect patients in two ways. They can, particularly in combination, greatly increase a person's risk of having a stroke. In addition, these risk factors can increase the likelihood of surgical complications.

How is carotid artery disease diagnosed?

In some cases, the disease can be detected during a normal checkup by a physician. In other cases further testing is needed. Some of the tests a physician can use or order include ultrasound imaging, arteriography, and magnetic resonance angiography (MRA). Frequently these procedures are carried out in a stepwise fashion: from a doctor's evaluation of signs and symptoms to ultrasound, MRA, and arteriography for increasingly difficult cases.

History and physical exam. A doctor will ask about symptoms of a stroke such as numbness or muscle weakness, speech or vision difficulties, or lightheadedness. Using a stethoscope, a doctor may hear a rushing sound, called a bruit (pronounced "broo-ee"), in the carotid artery. Unfortunately, dangerous levels of disease sometimes fail to make a sound, and some blockages with a low risk can make the same sound.

Ultrasound imaging. This is a painless, noninvasive test in which sound waves above the range of human hearing are sent into the neck. Echoes bounce off the moving blood and the tissue in the artery and can be formed into an image. Ultrasound is fast, risk-free, relatively inexpensive, and painless compared to MRA and arteriography.

Arteriography. This can be used to confirm the findings of ultrasound imaging which can be uncertain in some cases. Arteriography is an X-ray of the carotid artery taken when a special dye is injected into the artery. A burning sensation may be felt when the dye is injected. An arteriogram is more expensive and carries its own small risk of causing a stroke.

Magnetic Resonance Angiography (MRA). This is a new imaging technique that avoids most of the risks associated with arteriography. An MRA is a type of image that uses magnetism instead of X-rays to create an image of the carotid arteries.

What is "best medical therapy" for stroke prevention?

The mainstay of stroke prevention is risk factor management: smoking cessation, treatment of high blood pressure, and control of blood sugar levels among persons with diabetes. Additionally, physicians may prescribe aspirin, warfarin, or ticlopidine for some individuals.