Carotid arteries are located on both sides of the neck and supply blood from the aorta (the main blood vessel from the heart) to the brain. These arteries are the main source of oxygen and other nutrients to the brain and face. Plaque build-up and subsequent clot formation in the carotid arteries is a leading cause of stroke accounting for a third of all strokes. Plaque formation or atherosclerosis (commonly known as ‘hardening of the arteries’) in the carotid artery is a similar condition to that seen in the heart and other arteries in the body.
A plaque that gets unstable and ruptures can form a clot which impairs blood flow in the brain causing a stroke. Occasionally, this clot will spontaneously get broken up by the body and the stroke is aborted. This is referred to as ‘transient ischemic attacks’ or TIA. The common presentations include weakness or numbness on one side of the body that occurs suddenly, blurred or loss of vision, inability to speak clearly, facial asymmetry, and uncoordinated movement. These symptoms are the hallmark of a stroke and should be treated as a medical emergency requiring immediate help.
The risk factors for carotid plaque formation are also similar to those for heart blockages:
-High blood pressure
-High level of blood cholesterol
-Genetic predisposition or a strong family history
The diagnosis of carotid artery disease can be readily done by your physician. By listening to your neck arteries with a stethoscope, your physician can often hear an abnormal sound caused by blockage in the carotid arteries. This is referred to as a ‘bruit’. Confirmation of these blockages is often done by an ultrasound test of the carotid arteries. A probe that emits ultrasound energy is held against the skin and the blockages are quantified based on the increased speed of blood flow across that area.
Direct visualization of the blockage can be performed by either a CT scan, MRI scan or x-ray angiography. X-ray angiography is performed by a catheter inserted in the groin artery and threaded up to the neck with direct contrast injections. This procedure is usually required to confirm blockages that are suggested by other techniques.
Medical Management: Mild to moderate carotid artery disease (<50%) is best treated with medicines to slow or halt the progression of disease. This is typically accomplished by using aspirin, Plavix or a combination of the two. Lifestyle management and risk factor reduction are pivotal. These include quitting smoking (causes injury to blood vessels and constriction), lowering high blood pressure and cholesterol (low salt diet that is rich in fruits, vegetables, and low fat dairy products as well as low in red meat and processed foods), increasing activity and losing weight. Mild to moderate blockages are monitored closely with repeat ultrasound of the carotid arteries.
Carotid artery disease that causes TIA or strokes and produces greater than 50% blockage or asymptomatic blockages greater than 80% should be treated either by surgery or stenting. Surgery is done through an incision in the neck to physically remove the plaque. This procedure is called ‘carotid endartectomy’. Typically performed under anesthesia, it requires 1-4 days of hospital stay. Normal activities can be resumed in a few weeks. Uncommon but possible complications include heart attacks, TIA, stroke or damage to facial nerves. This has been the traditional approach for treating severe carotid stenosis.
More recently, carotid stenting has been developed as an alternative treatment modality. Over the last decade, the technique has been refined to where it can be performed with similar results and complication risks as with surgical treatment. The procedure is similar to a heart catheterization performed by inserting catheters in the leg artery. A filter is deployed above the blockage to trap any debris that may be released while the stent is placed. A small metal mesh tube, called a stent, is used to compress the plaque deposit against the arterial wall and avoid clot formation. Currently, this procedure is available to patients considered to be high risk for surgery including patients with severe heart or lung disease, previous radiation to the neck, a very high or low level of blockage, both carotid arteries being involved, or patients requiring concurrent heart bypass surgery. Overnight stay is required in the hospital and patients recover from the procedure in a few days. Numerous studies are ongoing that are comparing the outcomes of surgery versus carotid stenting in lower risk patients. Based on these results, carotid stenting may be offered to more patients in the near future.