Carotid artery stenosis or coronary artery disease refers to a narrowing of the carotid arteries, the major arteries in the neck that supply the brain with blood from the heart. A common cause of the condition is atherosclerosis, where fatty deposits build up in the inner walls of the blood vessels and cause the lumen or space in the arteries to narrow.
Eventually, the carotid arteries can become completely blocked, which decreases blood flow to the brain and increases the risk of stroke. Carotid artery stenosis accounts for around 30% of stroke cases. The likelihood of coronary artery stenosis developing is increased by certain risk factors which include:
- High blood pressure,
- Older age
- Family history of atherosclerosis
- High cholesterol
- Lack of physical activity
Men aged younger than 75 years are at an increased risk of developing carotid artery stenosis compared with women under this age. After the age of 75, women are at a greater risk of the condition.
Patients with this condition do not usually present with any symptoms. The atherosclerosis progresses over time and fatty deposits build up in the arteries without causing any warning signs until the patient is at risk of transient ischemic attack (TIA), which is often the first sign patients present with. A TIA is caused by a clot that has formed in the affected artery, dislodging and travelling towards the brain where it lodges in a smaller artery. This can cause similar symptoms to those seen in stroke such as paralysis in one side of the body, difficulty speaking or responding, confusion, difficulty balancing, headache and blurred vision.
Unlike stroke, a TIA only lasts for a brief period and usually resolves within a few hours. However, the event is a warning sign that the patient is at risk of stroke, which can lead to severe disability and even death. Research has shown that people who have had a TIA are at ten times the risk of major stroke compared with those who have not experienced a TIA.
A diagnosis of carotid artery stenosis usually involves the following steps:
Doctor’s assessment - A doctor will obtain details of symptoms and medical history as well as performing a physical examination. The doctor will be interested in any risk factors for carotid artery disease, as well as symptoms that indicate TIA. The doctor may listen to arteries in the neck using a stethoscope to check for an abnormal sound referred to as a “bruit”. This sound can occur when blood flow is turbulent due to carotid artery disease. Detection of a carotid bruit usually leads to a referral for carotid ultrasound to assess blood pressure and blood flow in the arteries; computed tomography or magnetic resonance imaging to check for evidence of stroke or other damage and computed tomography angiography which is also used to assess blood flow in the arteries. These tests are described in more detail below.
Carotid ultrasonography - Carotid ultrasonography is the most commonly used test for determining whether coronary artery stenosis is present. This is a non-invasive, painless technique that uses high intensity sound waves to generate structural images of the carotid arteries. It is used to check for plaque build up, blood clots and narrowing of the arteries. The amount and velocity that blood is moving at through the vessels can be assessed using Doppler ultrasound.
Carotid angiography - This is an invasive procedure that involves a catheter being inserted into a vein in the patient’s arm or leg and guided towards the carotid arteries. A contrast dye is then passed through the catheter and real-time X-ray images of the arteries are taken. This enables a doctor to visualize the anatomy of these arteries and detect any abnormalities.
CT Scan - A computed tomography (CT) scan uses X-ray in conjunction with computer technology to generate detailed images of the head and neck. The technique can be used to generate cross-sectional 2-D and 3-D images of the carotid arteries and the brain. The CT scan uses radiation to create images. Therefore, the risk to patients is weighed up against the benefits before this procedure is performed.
Magnetic resonance angiography - This technique employs radio waves and magnetic fields to create detailed images of the carotid arteries and brain. This procedure can often detect even small cardiovascular events that have occurred in the brain. A contrast dye may also be used to highlight the arteries.
If a patient is diagnosed with carotid artery disease, treatment is then initiated. The treatment will depend on how severe the stenosis is. For some patients, lifestyle changes and medication may be sufficient to improve the condition, while others may require a minimally invasive procedure called carotid angioplasty and stenting to open up the artery. Others may need a more invasive intervention called carotid endarterectomy to remove the blockage in the artery.