Carotid Artery Disease

Author
Gerrit Winkelaar MD

Title
Carotid Artery Disease

What is Carotid Artery Disease?
The carotid arteries are the two large vessels that run up either side of the neck.  They then divide into two large branches.  One is the  external carotid artery that supplies blood to the face and neck.  The other is the internal carotid artery and it supplies blood to the eye and brain.  The point at which the artery divides is slightly wider and is called the carotid bulb.  Atherosclerosis, or plaque formation, seems to occur preferentially at this site, causing narrowing of the blood vessel and reduces blood flow to the brain and eye.   This can result in stroke or blindness.

What causes Carotid Artery Disease?
A build up of plaque made up of cholesterol, calcium, fibrotic tissue and cellular debris called atherosclerosis thickens and narrows the arteries in the neck.
Sometimes this plaque softens and breaks open.  When this happens, clot-forming cells called platelets stick to the plaque.  Sometimes the whole artery will clot and reduce the flow of blood to your brain causing a stroke. More often, debris from the plaque or bits of platelet plug will travel up the artery, blocking the blood vessels within the eye or brain, causing blindness or stroke.

What are the symptoms of  Carotid Artery Disease?
Carotid artery disease occurs more frequently as we age and affects up to 3% of the general population.  Most of the time there are no symptoms.  The first symptom may be a stroke with tingling or weakness of one side of the body or face, slurred speech or difficulty speaking or sudden blindness in one eye.  Sometimes these symptoms only last a short time and resolve totally.  This is a mini-stroke or TIA (transient ischemic attack).  Just because the symptoms go away, it is still important to seek medical attention immediately.  These mini-strokes can be an early warning of impending major, permanent stroke if they are not investigated and treated.

Diagnosis and tests for Carotid Artery Disease
Your doctor will start by taking a health history and examining you.  This will help determine your risk factors for developing carotid artery disease.  These include smoking, high blood pressure, high cholesterol and family history.  The first test your doctor will usually order is an ultrasound of the carotid vessels.  This is a noninvasive test that uses sound waves to look at the carotid arteries and to assess the blood flow through them.  Sometimes more information is required and a CT angiogram or Magnetic Resonance Angiogram (MRA) may be ordered.  These tests involve giving contast (dye) and use of either xrays for CT, or magnetic fields for MRA to create a picture of the artery.

Lifestyle modification for Carotid Artery Disease
If you smoke you are very likely to develop progressive atherosclerosis.  Quitting smoking will not necessarily reverse the formation of plaque in the carotid arteries but it may stop the progression of narrowing and reduce the possiblity of plaque breakdown that can trigger a stroke.  Other factors such as exercise, weight loss and a diet low in saturated fat can reduce the risk of developing atherosclerotic disease.

Non-surgical and medical management for Carotid Artery Disease
Medications that prevent platelets from sticking to the plaque surface are important in preventing stroke.  The most commonly used medication for this is aspirin.  A  dose of 81 - 325 mg daily is recommended.  If you are intolerant of aspirin, your doctor will discuss alternate medications that can be used.  Studies have also shown that being on a statin agent for cholesterol control can induce remodelling and even regression of the carotid plaque.  High blood pressure itself is a risk factor for stroke and developing atherosclerosis and should be treated with medication. If you are diabetic, good control of your blood sugar levels is also important.

Guidelines for Intervention for  Carotid Artery Disease
The goal of intervention on a carotid narrowing is to reduce your risk of stroke.  If you have had a non-disabling stroke or TIA due to carotid stenosis and have over 70% narrowing, your doctor will usually recommend intervention to get rid of the narrowed area, either with surgery or angioplasty, described below.  If you have symptoms and 50-69% narrowing, intervention may be recommended, but risk factor treatment and medication changes might be tried first.  If you have no symptoms of stroke or TIA, the recommendation for intervention is often based on factors such as your age, degree of narrowing and medical fitness for the procedure.

Surgical treatment for  Carotid Artery Disease
Surgery for carotid artery disease is perfomed through an incision in the front of your neck under local or general anesthesia, depending on your surgeon's preference.  The carotid artery is then opened and the plaque removed, leaving a smooth surface.  The artery is then closed directly with sutures or by sewing a patch to the edges of the opening.  Most patients will spend at least one night in the hospital after the surgery.  This procedure is called a carotid endarterectomy and has been shown to be a safe, effective and durable operation to reduce stroke risk when performed by qualified, trained surgeons.

Endovascular Treatment for Carotid Artery Disease
Angioplasty and stenting of the carotid artery is a newer treatment that has become more widely available in Canada.  It involves the placement of a catheter via an artery in the groin under local anesthetic.  The catheter is passed into the carotid artery by xray guidance.  A small balloon is then inflated across the narrowing, pushing the plaque out of the way. A metal wire cylinder called a stent is then placed in the area to keep the artery open.  Most patients spend a night in hospital afterwards.  This treatment is still considered to be controversial, but may be considered when patients are thought to be too high risk to undergo carotid endarterectomy.

When should I see my doctor?
If you experience sudden weakness or tingling of one of your arms, legs, or one side of your face, slurred speech or difficulty speaking or blindness in one eye, you should seek medical attention immediately, even if the symptoms completely resolve after a short time.  If you smoke, have high blood pressure, diabetes, high cholesterol and/or a family history of atherosclerosis, you should see your doctor regularly for counselling and treatment of these conditions to reduce your likelihood of developing carotid artery disease.

References and Resources
1. Prevalence of Asymptomatic Carotid Artery Stenosis in the General Population.
An individual Participant Data Meta-analysis.  Stroke. 2010;41:00-00.
2.  The effect of statins on carotid plaque morphology; a LDL-associated action or one more pleotropic effect of statins?  Atherosclerosis.2010 Nov;213(1):8-20.
3.  10 year stroke prevention aftersuccessful carotid endarterectomy for asymptomatic stenosis (ACST-1): a multicentre randomised trial. Lancet. 2010;25;376(9746):1074-1084.
4. The Carotid Revascularization Endarterectomy versus Stenting Trial(CREST): stenting versus carotid endarterectomy for carotid disease.  Stroke. 2010 Oct;41(10 Suppl):s31-4.
5.  The North American Symptomatic Carotid Endarterectomy Trial.  Surgical results in 1415 patients.  Stroke. 1999 Sept;30(9): 1751-8.
6. www.vascularweb.org

Comments/notes from the author

Probably need to add a bit on angiography in investigations such as:  Angiography is performed by threading a catheter via a groin artery into the carotid artery and taking xrays while contrast is injected through the cahteter.  There are risks to having this procedure and so it is usually not one of the first tests your doctor will order for carotid disease assessment.