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updated: 9/10/2012 8:27 AM

Clearing blocked carotid artery can prevent bigger stroke

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Q. I had a mild ischemic stroke. Now my doctor wants to do a carotid endarterectomy. Is this necessary?

A. It might be necessary, but I don't know enough about your case to say for sure. As I explain what an ischemic stroke is, and what a carotid endarterectomy is and when it is valuable, I hope you'll be able to tell if you could benefit.

An ischemic stroke is caused by a blockage in a blood vessel (an artery) that supplies blood to a part of your brain. When all blood flow to a part of the brain stops for more than a few minutes, that part dies. This is called a stroke. Usually, but not always, this causes symptoms.

Sometimes a blockage is just temporary and causes only brief symptoms and no lasting brain damage. This is called a transient ischemic attack (TIA). (I've listed the symptoms of a TIA on my website.)

There are many possible causes of a blockage that causes an ischemic stroke. In all of us, the heart pumps blood first through the largest artery, the aorta, and then into smaller arteries. For example, the two carotid arteries, one on each side of the neck, carry blood to arteries inside the brain. Inside the brain, the arteries get narrower and narrower.

Diseases of the heart, aorta and arteries in the neck or inside the brain can all lead to blockages. Blood clots or little pieces of the wall of the heart, aorta and arteries of the neck can break off and travel through the progressively narrower arteries until they get wedged in an artery, stopping blood flow to a part of the brain.

It sounds like your doctor thinks you had a mild stroke that resulted from a blockage in one of the carotid arteries in your neck. The most common cause of such a blockage is a plaque of atherosclerosis. Your doctor may think that a small piece of that plaque broke off, traveled downstream and blocked a small artery in your brain. If I were your doctor, I'd be worried that a bigger piece could break off and cause a big stroke.

A carotid endarterectomy is a surgical procedure to remove a blockage in a carotid artery. In general, carotid endarterectomy is performed on people who have had a TIA (not a stroke) or, like you, a mild stroke and in whom a major stroke appears imminent.

The surgeon makes an incision in the neck, opens the artery, cleans out the plaque and stitches you back up. When someone is too frail for surgery, an alternative to carotid endarterectomy is carotid angioplasty and a stent. As is done with the heart, a catheter is passed to the point of blockage, and a small wire mesh cylinder (the stent) expands to squash the blockage.

• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: