Carotid artery disease
The carotid arteries supply the brain with freshly oxygenated blood. There are two carotid arteries (with internal and external branches) on either side of the windpipe. Blockage of these arteries occurs over time through a process called atherosclerosis, or the build up of plaque. Plaques are made up of deposits of cholesterol, calcium and other cellular components. Plaques not only make the arteries ‘hard,’ they grow over time and can narrow the arteries or even completely block the flow of blood to the brain. Small pieces of the plaque called emboli can break off and occlude branch arteries in the brain or eye.
The most common site for atherosclerosis in the carotid artery is at the place where the common carotid artery splits into its internal and external branches (the carotid bifurcation).
The carotid arteries supply blood to the parts of the brain responsible for thinking, speech, the sense of touch and movement. The carotid arteries also supply blood to the eyes. Both emboli and restricted blood flow or complete blockage have serious consequences for brain cells and the eye. Ischemia occurs when blood flow to the brain or eye damages cells. An infarction occurs when the cells die. A transient ischemic attack, or “mini-stroke,” is an ischemic event that results in the temporary loss of brain function. If the resulting loss of brain function is permanent, it’s called a stroke (an infarction or brain attack). Partial or complete blindness in one eye can occur if plaque breaks off and occludes the artery to the eye; this blindness may be temporary (amaurosis fugax) or permanent.
The most serious consequence of carotid artery disease is stroke. A stroke can either be caused by the breaking off of a piece of plaque that travels downstream and blocks a portion of the blood flow to the brain, or by blockage in the carotid artery. More than half of the strokes that occur in the United States can be attributed to carotid artery disease.
Strokes often leave people unable to talk, use one arm or walk properly. Often these functions can be regained through rehabilitation.
Usually, there are no symptoms of carotid artery disease. Those at high-risk should be checked periodically by a physician who can listen for an abnormal rushing sound in the neck using a stethoscope. This sound, called a “bruit,” may indicate the presence of a plaque.
Transient ischemic attacks (TIA), or “mini-strokes,” or transient blindness in part or all of one eye, may signal an oncoming stroke.
A person having a TIA may experience temporary symptoms lasting anywhere from a few minutes to no longer than 24 hours. These symptoms may include:
- Sudden weakness and/or numbness of the arm, leg and/or face on one side of the body
- Slurring of speech, difficulty talking or difficulty understanding speech
- Loss of vision in one eye
Because the chances are great that these symptoms may be warning signs of a stroke, anyone experiencing them should seek emergency medical care. Immediate treatment can increase the chance of a full recovery.
The risk factors for carotid artery disease are those associated with atherosclerosis:
- Hypertension (high blood pressure)
- Older age
- Gender: men have a higher risk before age 75; women have a high risk after 75
- Family history
- Race or ethnicity
- Genetic factors
- Hyperlipidemia (elevated fats in the blood)
Patients known to have atherosclerosis and diagnosed with coronary artery disease or peripheral artery disease are at greater risk for carotid artery disease and stroke.
An abnormal rushing sound in the neck, called a “bruit,” heard through a stethoscope may be the first indication of the presence of a plaque.
A special ultrasound of the neck, a carotid artery duplex scan, is the preferred method for both screening and to determine the extent of blockage. This method produces both an image of the blocked artery and measures the velocity and direction of blood-flow in the vessel. Magnetic resonance angiogram and standard angiograms are also used to diagnose carotid artery disease. A CT scan or MR imaging study of the brain is used to confirm if a stroke has already occurred.
Medication and lifestyle changes
Patients who have narrowing of a carotid artery or a history of stroke or TIA's ("mini-strokes") should quit smoking immediately, attempt to lower cholesterol levels through diet and exercise regularly. Physicians may also prescribe medication to control high blood pressure, lower blood cholesterol levels and block the function of platelets.
Severe blockage of a carotid artery (more than 60 percent) can be repaired by a surgical treatment called carotid endarterectomy. During this procedure, an incision is made in the neck, the plaque removed and blood-flow returned to normal. The procedure has a high success rate and most patients go home the following day and quickly resume normal activities.
A newer technique called carotid artery stenting is also used to treat carotid artery disease. It involves the placement of a catheter in an artery of the groin through a small nick in the skin. A balloon is advanced to the neck where it is inflated, dilating the artery wall. A tube-like metal stent is then put in place to keep the artery open and the blood flowing freely. Patients usually stay in the hospital for one or two days and quickly resume normal activities.