What is a carotid endarterectomy?
A carotid endarterectomy is a surgical procedure in which a doctor removes fatty deposits from one of two main arteries in the neck. These blood vessels are called carotid arteries and supply blood to the brain. Carotid artery problems become more common as people age. The disease process that causes the buildup of fat and other material on the artery walls is called atherosclerosis, popularly known as “hardening of the arteries.” The fatty deposit is called plaque while the narrowing of the artery is known as stenosis. The degree of stenosis is usually expressed as a percentage of the normal diameter of the opening.
Why is surgery performed?
Carotid endarterectomies are 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 highly beneficial when performed by surgeons and in institutions that can match the standards set in those studies. The surgery has been found to be highly beneficial for persons who have already had a stroke or experienced the warning signs of a stroke and have a severe stenosis of 70 percent to 99 percent. In this group, surgery reduces the estimated 2-year risk of stroke by more than 80 percent, from greater than 1 in 4 to less than 1 in 10.
Surgery reduces the 5-year risk of stroke by 6.5 percent for patients with 50 to 69 percent stenosis, compared to an 80 percent risk reduction for patients with greater than 70 percent stenosis. Patients with 50 percent stenosis or lower do not show enough benefit from endartarectomy to outweigh the risks of the procedure. With the completion of the NASCET trial, patients with moderate stenosis will be better able to decide whether to risk surgery in order to prevent possible future strokes. The point at which surgery begins to confer a significant benefit seems to be around the time that the artery is 50 percent blocked.
In another trial, the procedure has also been found highly beneficial for persons who are symptom-free but have a severe stenosis of 60 percent 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.
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 U.S. 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 has a 40-year history and was first described in the mid-1950s. It began to be used increasingly as a stroke prevention measure in the 1960s and 1970s. The number of endarterectomies 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.
How much does a carotid endarterectomy cost?
The total average cost for the diagnostic tests, surgical procedure, hospitalization and followup care is about $15,000.
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 (whether in the brain or in the eye), blockage of the carotid artery on the opposite side, and the use of aspirin immediately prior to the surgery. 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 most cases, the disease can be detected during a normal checkup with a physician. Some of the tests a physician can use or order include history and physical exam, doppler ultrasound imaging, oculoplethysmography (OPG), computed tomography (CT), arteriography and digital subtraction angiography (DSA), and magnetic resonance angiography (MRA). Frequently, these procedures are carried out in steps. First, there is the doctor’s evaluation of signs and symptoms then an ultrasound. Arteriography, DSA or MRA are reserved for difficult diagnoses.
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 “brew-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 a sound.
Doppler 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. Unfortunately, there is a small possibility of error in an ultrasound study. A stenosis with a high level of risk will occasionally be incorrectly reported as a low-risk finding. Conversely, a stenosis with a low level of risk will sometimes be reported as a high level of risk. In carefully calibrated ultrasound laboratories, ultrasound studies can be up to 95 percent accurate and offer visualization of the anatomy, evaluation of the blood flow rate and turbulence, and characterization of the plaque. Performing an ultrasound study requires a great deal of skill which is not always available.
Oculoplethysmography (OPG). This procedure measures the pulsation of the arteries in the back of the eye. It is used as an indirect check for blockages in the carotid arteries.
Computed Tomography (CT). This test produces a series of cross-sectional X-rays of the head and brain. It cannot detect carotid artery disease but may be ordered by a doctor to investigate other possible causes of symptoms. The test is also called a CAT scan or computer assisted tomography.
Arteriography and Digital Subtraction Angiography (DSA). Arteriography is an X-ray of the carotid artery taken when a special dye is injected into another artery in the leg or arm. A burning sensation may be felt when the dye is injected. DSA is also an X-ray study of the carotid artery. It is similar to arteriography except that less dye is used. A person having a DSA must remain still during the test. These invasive procedures are more expensive and carry their own small risk of causing a stroke.
Magnetic Resonance Angiography (MRA). This is a very new imaging technique that is more accurate than ultrasound yet avoids the risks associated with X-rays and dye injection. An MRA is a type of magnetic resonance image that uses special software to create an image of the arteries in the brain. A magnetic resonance image uses harmless but powerful magnetic fields to create a highly detailed image of the body’s tissues.
What is the “best medical therapy” for stroke prevention?
The mainstay of stroke prevention is risk factor management: smoking cessation, treatment of high blood pressure and heart disease, and control of blood sugar levels for those with diabetes. Additionally, physicians may prescribe aspirin, warfarin, or ticlopidine.
Prepared by the Office of Scientific and Health Reports of the National Institute of Neurological Disorders and Stroke, National Institutes of Health in January 1998.