Healthy lifestyle prevents narrowing of carotid arteries
Harvard Medical School Adviser by the Faculty of Harvard Medical School
My father was recently diagnosed with carotid stenosis. I'd like to learn more about the condition. In particular, how can I prevent developing it myself?
The carotid arteries in your neck play an important role in keeping your brain healthy and functioning properly. Your brain must receive an uninterrupted supply of blood because nerve cells require a constant supply of oxygen. Even a brief disruption stuns nerve cells, impairing their function. More prolonged oxygen deprivation kills the cells.
Carotid artery stenosis is the narrowing of these arteries due to the buildup of cholesterol-rich plaques. When the narrowing is moderate or severe, clots can form on the plaques and then break off and travel to the brain, where they may interfere with blood flow.
Brief or partial interruptions of blood flow cause transient ischemic attacks (TIAs). But prolonged or complete blockages cause strokes. If only a small, noncritical area of your brain is affected, you may not notice the damage. Unfortunately, however, the damage is often very noticeable indeed, as we'll discuss.
Nearly nine of every 10 strokes are caused by a blocked artery (ischemic stroke). The blockage can occur right in an artery in the brain (thrombotic stroke), but it is more commonly caused by blood clots that break off from the heart or from an artery that carries blood to the brain (embolic stroke).
That's where the carotid arteries come in. Healthy carotids carry blood to the front part of the brain. But when diseased, they are a major cause of TIAs and strokes. Simple, noninvasive tests can diagnose carotid artery disease, and treatment can reduce the risk of stroke.
In a healthy person, the internal carotid artery is about 5 millimeters wide. That's about the diameter of a pencil eraser, and is more than wide enough to bring the brain all the blood it needs. Narrowing, or stenosis, of the carotid is considered mild when it reduces the width of the artery by less than 50 percent. Narrowing of 50 percent to 69 percent is considered moderate. Narrowing of 70 percent to 99 percent is considered severe carotid stenosis.
What narrows the carotid artery? In nearly all cases, it's atherosclerosis. This is the same disease that causes heart attacks by blocking coronary arteries. In atherosclerosis, cholesterol-laden plaques build up in the artery wall, gradually narrowing the vessel. But in most cases, it's not the plaque itself that does the final damage.
In carotid stenosis, the culprit is a blood clot that breaks away from the plaque and is carried by the blood to the brain or eye. It then lodges in a smaller artery. If the clot breaks into tiny fragments that are carried away, the brain cells recover -- that's why the symptoms of a TIA resolve within 24 hours. But if the clot stays put, brain cells die, causing the irreversible damage of stroke.
People who already have carotid stenosis may need to take additional steps to prevent a stroke. Two approaches are available: Aspirin or another medication that prevents clots from forming on plaques, and surgery or angioplasty with stenting to open the narrowed artery.
Everyone should understand the importance of TIAs, which indicate vascular abnormalities that could lead to a stroke.
TIAs begin abruptly, and they also resolve relatively fast. A typical TIA lasts just two to 15 minutes, and half of all patients are back to normal in less than an hour. By definition, symptoms that persist for more than 24 hours are not due to TIAs, but strokes.
TIAs caused by carotid stenosis often produce visual abnormalities, like sudden, painless loss of vision in one eye. Vision is restored to its previous state when the TIA resolves.
TIAs due to carotid stenosis can also affect other parts of the body. Temporary clumsiness, weakness or numbness in the face, hand or leg can occur. Slurred speech is very common.
TIAs should be taken seriously because they warn of a possible future stroke. And TIAs must be diagnosed and treated promptly because the risk of stroke is highest within the first 30 days. Urgent treatment can reduce that risk by up to 80 percent.
The best way to prevent TIAs and strokes is to keep your blood vessels healthy. Like coronary artery disease, carotid artery disease is most often caused by smoking, hypertension, high cholesterol, lack of exercise, diabetes and obesity. Stress may also contribute.
All these risk factors can be controlled. The key is not smoking, getting regular exercise, and having regular checkups to detect and treat high blood pressure and abnormal cholesterol levels. Another crucial component is a healthy diet that's low in saturated fat, trans fat, cholesterol and salt, but high in fish, fiber, fruits and vegetables.
Doctors have come a long way in diagnosing and treating carotid stenosis -- but you can do even better by preventing the problem with wise lifestyle choices.
(Submit questions to firstname.lastname@example.org.)
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