A carotid endarterectomy may be needed if one or both of your carotid arteries becomes narrowed by a build-up of fatty deposits (plaque).
There is a risk that the narrowing in the carotid arteries, known as stenosis, could cause a stroke or a transient ischaemic attack (TIA).
Stroke and TIA risk
There are two ways that a stroke or TIA could occur if the flow of blood through your carotid arteries becomes blocked or restricted. These are described below.
- The carotid artery is completely blocked, limiting the blood supply to your brain and causing a stroke; this type of stroke is known as an ischaemic stroke.
- A blood clot forms on the roughened surface of the carotid artery and breaks off: the blood clot may block one or more arteries in the brain; this type of stroke is known as an embolic stroke.
Diagnosing carotid artery disease
Carotid artery disease is usually diagnosed if a person has the symptoms of a stroke or TIA, such as the face drooping on one side, numbness or weakness in the arms or legs, speech problems or loss of vision in one eye.
Read more about the symptoms of a stroke.
However, occasionally stenosis (narrowing of the carotid arteries) may be diagnosed if you are having tests for another reason and the doctor testing you notices that your arteries are narrowed. This is called an asymptomatic carotid stenosis.
If you have had a stroke or a TIA in the recent past, you will be referred for some brain imaging tests. This will allow the blood supply to your brain to be checked and any narrowing in your carotid arteries to be diagnosed.
Ultrasound is usually used to check if there is any narrowing in your arteries and to determine whether it is severe enough for you to benefit from having surgery. Ultrasound is a painless procedure that involves passing a probe over your neck so that your arteries can be viewed on a television screen.
If your arteries are narrowed, you may need to have further tests to confirm the diagnosis. You will either have a computed tomographic angiogram (CTA) or a magnetic resonance angiography (MRA), which are both detailed medical imaging techniques.
Narrowed arteries
If tests indicate that your carotid arteries are narrowed, the severity of the narrowing (stenosis) will be graded.
In the UK, the most common grading system that is used is the NASCET scale (North American Symptomatic Carotid Endarterectomy Trial).
The scale has three categories of measurement:
- minor: 0%-49% narrowed
- moderate: 50%-69% narrowed
- severe: 70%-99% blocked
When surgery is recommended
The National Institute for Health and Clinical Excellence (NICE) recommends that people who have had a stroke or a TIA, and have severe stenosis, should have a carotid endarterectomy performed on them.
You should be assessed within a week of the start of your stroke or TIA symptoms, and the operation will ideally be carried out within two weeks of the start of your symptoms.
It is absolutely crucial that you seek medical advice as soon as possible after the onset of symptoms. This is because surgery has the best chance of preventing a stroke if it is performed as soon as possible.
Surgery will sometimes be recommended if you have not previously had a stroke or a TIA, but you are found to have severe stenosis.
Surgery will not be recommended if you have minor stenosis (less than 50%). This is because surgery has the most benefit for people with moderate and severe stenosis (over 50%), with the maximum benefit being seen in those with severe stenosis (70%-99%).
A carotid endarterectomy is not of any benefit in people with a complete blockage of their carotid artery.
