A carotid endarterectomy may be needed if one or both of your carotid arteries become narrowed because of a build-up of fatty deposits (plaque).
This is known as carotid artery disease or carotid artery stenosis, and it significantly increases your risk of having a stroke or a transient ischaemic attack (TIA).
Why carotid artery disease develops
Normal healthy arteries are elastic and smooth on the inside, allowing blood to easily flow through them. As a person gets older, plaque can build up inside the arteries, making them narrower and stiffer. This process is called atherosclerosis.
As well as ageing, there are several other factors that can contribute to a build-up of plaque, including:
Read more about the causes of atherosclerosis.
Carotid artery disease and stroke
There are two ways a stroke or TIA could occur if the flow of blood through your carotid arteries becomes blocked or restricted. These are described below:
- an ischaemic stroke – if the carotid artery is completely blocked and limits the blood supply to your brain
- an embolic stroke – if a blood clot forms on the roughened surface of the carotid artery and breaks off, it may block one or more arteries in the brain
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 a loss of vision in one eye.
However, narrowing of the carotid arteries may be diagnosed if you're having tests for another reason and the doctor testing you notices your arteries are narrowed. This is called an asymptomatic carotid stenosis.
If you've recently had a stroke or a TIA, you'll be referred for some brain imaging tests. This allows the blood supply to your brain to be checked and any narrowing in your carotid arteries to be diagnosed.
Several tests can be used to examine your carotid arteries and find out how much plaque has built up inside them. These include:
- duplex ultrasound scan – sound waves are used to produce an image of your blood vessels and measure the blood flow through them; it can also show how narrow your blood vessels are
- computerised tomography (CT) scan – a series of X-rays are taken at slightly different angles, and a computer assembles the images to create a detailed picture of the inside of your body
- computed tomographic angiogram (CTA) – a special dye is injected into a vein and a CT machine is used to take X-rays to build up a picture of your neck arteries
- magnetic resonance angiography (MRA) – a magnetic field and radio waves are used to produce images of your arteries and the blood flow within them
An ultrasound scan is usually used first to check if there's any narrowing in your arteries and to determine whether it's severe enough for you to benefit from having surgery.
If your arteries are narrowed, you may need to have further tests to confirm the diagnosis, such as a CTA or MRA.
Grading narrowed arteries
If tests indicate your carotid arteries are narrowed, the severity of the narrowing (stenosis) will be graded to determine if you need surgery.
In the UK, the most common grading system used is the North American Symptomatic Carotid Endarterectomy Trial (NASCET) scale. The scale has three categories:
- minor – 0-49% narrowed
- moderate – 50-69% narrowed
- severe – 70-99% blocked
When is surgery recommended
The National Institute for Health and Care Excellence (NICE) recommends that people who have had a stroke or TIA and have a moderate or severe stenosis should have a carotid endarterectomy.
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 when your symptoms started.
It's crucial that you seek medical advice as soon as possible if you develop symptoms of a stroke or TIA. Surgery has the best chance of preventing a further stroke if it's performed as soon as possible.
Surgery will sometimes be recommended if you haven't previously had a stroke or a TIA, but you're found to have severe stenosis.
Surgery won't 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 (more than 50%). The maximum benefit is seen in those with severe stenosis (70-99%).
A carotid endarterectomy isn't of any benefit in people with a complete blockage of their carotid artery.