Carotid artery disease, or carotid artery stenosis, refers to a narrowing within the carotid arteries that is usually caused by the buildup of plaque within the artery, called atherosclerosis.
The carotid artery supplies blood and oxygen to the brain as well as the head and neck. There are two common carotid arteries - one on each side of the neck - that split into two arteries: the internal and external carotid arteries. The internal carotid artery supplies blood and oxygen to the brain and the external carotid artery supplies blood and oxygen to the face, neck, and scalp.
For many people, carotid artery stenosis does not cause symptoms. However, when pieces of plaque break off (called emboli) and travel to the brain, blood flow to an area of the brain is blocked and causes a stroke. 30% to 50% of strokes are caused by carotid artery disease. Since stroke is the third leading cause of death in Canada, the diagnosis and treatment of this condition is critical.
People who smoke, are overweight, are inactive, or who have high cholesterol, high blood pressure, or high blood sugar levels (e.g., diabetes) are at an increased risk of carotid artery disease.
Because plaque can also build up in arteries other than the carotid arteries, people who have carotid artery disease may also have coronary artery disease, or heart disease.
Carotid artery disease is caused by narrowing of the carotid artery, usually caused by atherosclerosis. Atherosclerosis is a buildup of plaque within the artery.
Plaques, which consist of cholesterol and other material, start to build up when there is damage inside the arteries. When plaques in the arteries break open or crack, platelets stick to the crack and form a blood clot. This can partially or completely block the carotid artery. For some people, a small piece of the plaque can break off and travel to the brain, cutting off blood supply to a certain area of the brain and causing a stroke.
Symptoms and Complications
Most people have no symptoms in the early stages of carotid artery disease, but as more of the carotid artery is blocked, symptoms associated with a transient ischemic attack (TIA) or stroke can occur. For some people, the first symptoms of carotid artery disease are those of a stroke or a TIA.
Symptoms of a stroke include:
- sudden, severe headache
- sudden, severe dizziness or difficulty walking
- sudden difficulty speaking
- sudden blurred vision in one or both eyes
- sudden weakness or numbness of the arms, legs, or face (usually only on one side of the body)
A TIA is also referred to as a mini-stroke. A TIA has the same symptoms as a stroke, but the symptoms go away within a day. If you experience symptoms of a stroke or a TIA, get immediate medical attention and do not drive yourself to the hospital. Early treatment is imperative to minimize damage to the brain and increase the chance that you will recover without permanent effects.
A stroke is the most serious complication of carotid artery disease.
Making the Diagnosis
Your doctor will perform a physical examination and ask you questions about your symptoms. As part of the examination, your doctor will listen to your carotid arteries with a stethoscope. If you have carotid artery disease, your doctor may hear bruits, which are swooshing sounds caused by changes in blood flow.
If your doctor suspects that you have carotid artery disease, they will order a test called a doppler ultrasound, which evaluates the blood flow through the carotid arteries using sound waves.
Some people may require additional tests such as an angiogram, a computer tomography angiogram (CTA), or a magnetic resonance imaging angiogram (MRA). Angiograms involve injecting a contrast agent ("dye") into a vein to evaluate the carotid arteries.
Treatment and Prevention
Treatment of carotid artery disease is aimed at reducing the risk of stroke and can include medications, lifestyle management, and surgery.
Medications that may be used to manage carotid artery disease include:
- medications to lower blood pressure
- "statin" medications (e.g., lovastatin, pravastatin, simvastatin, atorvastatin*) to lower cholesterol levels
- medications to reduce blood sugar levels
- antiplatelet medications such as acetylsalicylic acid (ASA) or clopidogrel that make platelets in the blood less likely to form a blood clot
Your doctor may also suggest that you eat a healthy diet, stop smoking, exercise, or lose weight to help reduce the risk of stroke. Your doctor and other health care professionals can help you implement lifestyle changes safely.
For some people at a high-risk of having a stroke or those who have symptoms due to carotid artery disease, their doctor may recommend a surgical procedure, such as:
- an endarterectomy, where plaques within the carotid artery are removed
- angioplasty with a stent, where the carotid artery is widened with a small balloon that is inflated at the end of a tube
Following the surgical procedure, a stent (mesh tube) is placed in the artery to keep the carotid artery open.
The best way to help prevent carotid artery stenosis is to manage risk factors. A healthy diet, exercise, and quitting smoking will all help to reduce the risk of developing carotid artery disease, as well as reduce the risk of stroke and heart disease. It is also important for people to control their blood sugar, cholesterol levels, and blood pressure to help reduce the risk of carotid artery disease and stroke.
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