If you’ve monitored your heart rate by placing your fingers on the pulsating blood vessel in your neck during an exercise session, you’re familiar with the carotid artery. There’s a carotid artery on each side of your neck, right next to the windpipe, and they are important lifelines–the passages through which blood flows from the heart to the brain. Without proper flow through these vessels, the brain is unable to function as it should.

A major impediment to proper blood flow anywhere in the body is atherosclerosis–hardening and narrowing of the arteries. When cholesterol-laden plaque forms in coronary arteries, it compromises blood flow to the heart and creates the risk of a heart attack. When blockages occur in the carotid arteries, it’s the brain that’s in danger.

About 250,000 strokes each year–one third of the total number–involve atherosclerosis of the carotid artery. In a typical scenario, a blood clot breaks away from a plaque deposit in the carotid artery and travels to the brain, resulting in a life-threatening emergency.

Symptoms of a stroke include sudden loss of coordination and balance, difficulty speaking, full or partial loss of vision and loss of feeling or function in the face, arms, legs or any part of the body–particularly on one side only. Symptoms occurring for only a brief period–a few minutes or a few hours–usually signal a mini-stroke or transient ischemic attack (TIA), which also requires urgent medical attention.

Keeping Arteries Clear
Whether in the coronary, the carotid or arteries in the lower part of the body, avoiding atherosclerosis is a lifelong process that involves eating a heart-healthy diet, getting regular exercise and not smoking. Persons with high blood pressure and diabetes need to be particularly vigilant about keeping their medical conditions under control.

During an examination, a doctor may be able to detect atherosclerosis through what is known as a carotid bruit–a blowing or swishing sound that comes with abnormal blood flow through the vessel. Most persons, however, are not aware of atherosclerosis in the carotid arteries until they suffer a stroke or mini-stroke.

If a bruit is heard or a patient suffers a stroke or mini-stroke, the next step might be a non-invasive ultrasound or MRI test to determine the location and extent of the blockage. In some cases, a doctor might also order contrast angiography. This test is more invasive and carries more risk but provides detailed x-ray views that are necessary in some cases to make a definitive diagnosis.

If the arteries are narrowed by less than 60 percent and there are no symptoms, aggressive lifestyle changes may be recommended, along with antiplatelet medications. Persons with blockages greater than 60 percent are usually advised to have the plaque removed surgically through a procedure known as carotid endarterectomy.

Carotid endarterctomy is considered the gold standard treatment, several times more effective than medication, but it requires a hospital stay, general anesthesia and the risk of infection and other complications associated with any surgery. It also can trigger a stroke, although this effect is not common.

An alternative, less invasive treatment that has emerged in recent years–balloon angioplasty and placement of stents–is similar to a procedure normally performed on coronary arteries.

A balloon-tipped catheter is threaded through the arteries to the site of blockage; when the balloon is inflated, the plaque is compressed against the wall of the blood vessel, widening the channel through which blood flows. A stent, or wire mesh tube, is then inserted to keep the artery from narrowing again.

Angioplasty plus stenting is minimally invasive, less expensive and does not require a hospital stay. It also lessens the risk of complications such as cutting through a cranial nerve.

A similar procedure has been used successfully for many years to clear cholesterol-clogged arteries near the heart and in the groin, and it’s theoretically a less risky option than carotid endarterectomy. The American Heart Association still considers carotid angioplasty investigative, however, until more controlled studies have been performed demonstrating its safety and effectiveness.

So far, research suggests that angioplasty is as effective as carotid endarterectomy in preventing strokes long term. In one series of more than 500 patients, fewer than one percent suffered a stroke within five years. The short-term risk of triggering a stroke, however, was even higher than with carotid endarterectomy, according to some early studies.

One reason is that balloons and stents occasionally shatter the surface of the plaque, causing particles to break off and float into small blood vessels in the brain where they can cause a stroke.

This kind of debris may also occur following coronary angioplasty, but it’s less of a problem there because of the numerous small blood vessels serving the heart. If one becomes plugged, another takes over. Injury to even one small area of the brain, however, can have disastrous consequences.

Filters May Be Solution
Recently, researchers have focused on devices such as filters that can be placed inside the artery to catch any debris that breaks away during the procedure. Early studies of these filters have demonstrated their safety and yielded promising results about their effectiveness.

In one study of 307 high-risk patients conducted by researchers at the Cleveland Clinic, angioplasty plus stents and a filter device was associated with significantly fewer negative after effects. According to results presented at the annual scientific meeting of the American Heart Association [November, 2002], only 6 percent of subjects undergoing angioplasty died or suffered a heart attack or stroke compared to 13 percent of patients having carotid surgery. In many of these patients, the filter became visibly clogged with particles; in some cases, the filter became so clogged that it had to be removed–but after the short-term risk of a stroke was over.

Another reason for the increased incidence of stroke may be that the procedure, performed on the carotid artery, is still relatively new and doctors are facing a learning curve. In one early study, the incidence of stroke after angioplasty was more than twice as high at centers performing fewer than 10 procedures compared to centers performing more than 10 procedures.

Among 250 consecutive patients at one hospital where frequent procedures are performed, there were no deaths and an 0.7 percent rate of major stroke within 30 days.

Persons considering carotid angioplasty are advised to look for a surgical team that performs frequent procedures and has a proven track record.

Studies comparing angioplasty to surgery are continuing. The Carotid and Vertebral Transluminal Angioplasty Study (CAVATAS), a large prospective study, found the two procedures comparable in terms of safety. The Carotid Revascularization Endarterectomy versus Stent Trial (CREST) is currently underway.

At this time, angioplasty is recommended primarily for patients who are poor candidates for surgery (because of severe heart or lung disease or other illnesses) but have blockages too severe to respond to medication and lifestyle changes.

Considering the successful use of angioplasty plus stents elsewhere in the body, doctors are optimistic that this minimally invasive approach will become increasingly useful and may some day become the treatment of choice for maintaining proper blood flow through the carotid arteries.

REFERENCES:
Sonia Alamowitch, et al, “Risk, Causes, and Prevention of Ischaemic Stroke in Elderly Patients with Symptomatic Internal-Carotid-Artery Stenosis,” The Lancet, April 14, 2001.
“Clot Filters: Preventing Strokes During Carotid Artery Procedures,” Harvard Heart Letter, January, 2002.
“Is Carotid Stenting Here To Stay? Pro & Con,” Family Practice News, September 1, 2000.
Ian Lane, John Byrne, “Carotid Artery Surgery for People with Existing Coronary Artery Disese,” Heart, January, 2002.
Mary Ann Moon, “Medicare Now Covers Placement of Carotid Stents,” Family Practice News, June 1, 2001.
Wendi Pope, “Angioplasty & Stenting in the Carotid: Carotid Angioplasty and Stenting May Soon Become the Treatment of Choice for Certain Patients with Severe Carotid Artery Disease. Get Ready. You May Soon Be Caring for These Patients,” RN, June, 2002.
J.F. Potter, et al, “Treatment of Patients with Carotid Stenosis,” The Lancet, December 8, 2001.
“Procedure Not as Effective as Endarterectomy,” Medical Devices & Surgical Technology Week, March 11, 2001.
“TIA Treatment Guidelines Revised,” Patient Care, January 15, 2000.
Mitchel L. Zoler, “Endarterctomy Beats Carotid Stenting in Trial,” Family Practice News, April 1, 2001.