The carotid arteries travel from just above the heart up through the neck to feed the brain. For many reasons, these major arteries may become narrow, decreasing the blood flow to the brain and increasing the risk of stroke.
The most common reason why these arteries become narrow or blocked is atherosclerotic disease. This is a condition where cholesterol sticks to the wall of the artery. (This is called plaque.) In other cases, the walls of the artery may split. (This is called a dissection. ) When this happens, blood can travel between the layers of the artery wall. This makes the inside of the artery narrower. It sometimes entirely blocks the artery. This may result in a stroke.
Other more rare conditions that can cause carotid stenosis include fibromuscular dysplasia and Takayasu's arteritis. In these diseases, there may be many areas of one artery (or many arteries) involved with narrowing
As the artery becomes narrower, less blood can flow to the brain. In addition, there is a greater risk of stroke. Clots can form in the artery because of the narrowing. The clot may then travel to the brain and completely block a blood vessel.
The narrowing of the carotid artery is known as carotid stenosis. The plaque in the artery is common in people who smoke, have diabetes, a family history of this problem, uncontrolled high blood pressure and high cholesterol.
Carotid artery narrowing may cause a temporary loss of sight in one eye that lasts only several minutes. This happens when a small clot breaks off of the carotid artery and travels to the artery that feeds the eye. This condition is known as amaurosis fugax.
Patients with plaque and narrowing in their carotid arteries will also frequently have plaque in the arteries to their heart and may be at increased risk for a heart attack. We do recommend that these patients be followed closely by their physician and that they take one aspirin each day unless otherwise instructed by their physicians.
Treating Carotid Artery Stenosis With Carotid Endarterectomy
Studies of patients with carotid stenosis but no symptoms have shown that as little as a 50% narrowing of the artery may increase the patient's risk for stroke. For otherwise healthy men with a 50% or greater narrowing of the carotid artery, recent studies have shown that they may benefit from surgery. This procedure is called carotid endarterectomy. During the surgery, the artery is cleaned out of the plaque.
For women the statistics are slightly different. A woman usually must have a narrowing greater than 70% to benefit from carotid endarterectomy surgery.
Treating Carotid Artery Stenosis with Stents
Sometimes a patient is not a candidate for carotid endarterectomy. This can help because of his or her general health. It can also happen is the narrow portion of the artery is too high up the neck to reach with surgery. In these cases, a stent can be placed in the carotid artery.
In this procedure, the patient has an angiogram. A small tube is placed in an artery in the groin. The tube is fed up through the artery to the point where the narrowing is. Then, a small alloy metal tube known as a stent is threaded through the first tube and placed in the narrow spot of the artery. Sometimes a balloon is used to open up the narrowed artery. The stent holds the walls of the artery open so more blood can flow through.
In the angiogram at the near right, the narrowing of the carotid artery (shown in the circle) can be seen. The angiogram on the far right shows the artery after a stent has been placed in it.
Not all patients are candidates for this procedure. Clinical trials are being done to compare the benefits of surgery to stents in different types of patients.