Coronary Angiography

What is coronary angiography?

Coronary angiography is a special X-ray of the coronary arteries.

Coronary arteries do not show up on a plain X-ray. With coronary angiography, dye is injected down the coronary arteries. The arteries and their smaller branches then show up clearly on an X-ray 'like a road map'. Dye is injected into the coronary arteries by using a catheter. (A catheter is a thin, flexible, hollow tube.) How this is done is described below.

Therefore, coronary angiography can show the exact site and severity of any narrowing of the coronary arteries. This helps the doctor to decide on what treatment you may need. For example, if the narrowing is mild and does not need surgery. Or, if the narrowing is severe and you should have a coronary artery bypass graft or coronary angioplasty. See separate leaflet called 'Coronary Angioplasty' for more detail on this procedure.

Understanding the arteries of the heart

The heart is mainly made of special muscle. This heart muscle pumps blood into arteries (blood vessels) which take the blood to every part of the body.

Like any other muscle, the heart muscle needs a good blood supply. The coronary arteries take blood to the heart muscle. The coronary arteries are the first arteries to branch off the aorta. The aorta is the large artery that takes blood from the left ventricle of the heart to the body.

What is angina and what causes it?

Angina is a pain that comes from the heart. The usual cause of angina is narrowing of one or more of your coronary arteries. This reduces the blood supply to a part or parts of your heart muscle. The blood supply may be enough when you are resting. However, your heart muscle needs more blood and oxygen when it works harder. For example, when you walk fast or climb stairs, your heart rate increases to deliver the extra blood. If the extra blood that your heart needs during exertion cannot get past the narrowed arteries, the heart 'complains' with pain.

The narrowing of the arteries is caused by atheroma. Atheroma is like fatty patches or 'plaques' that develop within the inside lining of arteries. (This is similar to water pipes that get 'furred up' with scale.) Plaques of atheroma may gradually form over a number of years in one or more places in the coronary arteries. In time, these can become bigger and cause enough narrowing of one or more of the arteries to cause symptoms.

The diagram below shows three narrowed sections as an example. However, atheroma can develop in any section of the coronary arteries.

How is coronary angiography done?

You lie on a couch in a catheterisation room. An X-ray machine is mounted above the couch. A catheter is inserted through a wide needle or small cut in the skin into a blood vessel in the groin or arm. Local anaesthetic is injected into the skin above the blood vessel. Therefore, it should not hurt when the catheter is passed into the blood vessel.

How do I prepare for a coronary angiography?

You should get instructions from your local hospital about what you need to do in the days leading up to the test. The sort of instructions may include:

• Before the day of the test you may need a blood test and an ECG to make sure you are OK to have the procedure.
• If you take a 'blood thinning' drug (anticoagulant), such as warfarin, then you are likely to need to stop this for 2-3 days before the test. (This prevents excessive bleeding from the site of the catheter insertion.)
• If you take insulin or drugs for diabetes, the timing of when to take these on the day of the test may need to be clarified.
• If you may be pregnant, you need to tell the doctor who will do the test.
• You may be asked to stop eating and drinking for a few hours before the test.
• You may be asked to shave both groins before the test.
• You will have to sign a consent form at some point before the test to confirm that you understand the procedure, understand the possible complications (see below), and agree to the procedure being done.

How long does coronary angiography take?

It usually takes about 30 minutes. In most cases it is done as a day-case procedure.

After the test

• The doctor will discuss what he or she found during the test. A letter is also sent to your GP giving details of the test results.
• You will need to rest for a few hours after the test. You should ask a friend or relative to accompany you home. Most people are able to resume their normal activities the next day.
• There may be some bruising at the site of the catheter insertion which may be a little sore when the anaesthetic wears off. Painkillers such as paracetamol will help to ease this.
• You may need to have some stitches removed after about seven days if a small cut was made to insert the catheter.

Are there any risks or side-effects?

Most of the side-effects are minor and may include:

• A bruise, which may form under the skin where the catheter was inserted (usually the groin). This is not serious, but it may be sore for a few days.
• The small wound where the catheter is inserted sometimes becomes infected. Tell your GP if the wound becomes red and tender. A short course of antibiotics will usually deal with this if it occurs.
• Some people get a short angina-type pain during angiography. This soon goes.
• The dye may give you a hot, flushing feeling when it is injected. Many people also describe a warm feeling in the groin when the dye is injected - as if they have 'wet themselves'. These feelings last just a few seconds (and the operator will tell you when they are about to inject the dye). Rarely, some people have an allergic reaction to the dye.

Serious complications are rare, but do sometimes occur. For example, some people have had a stroke or a heart attack (myocardial infarction) during the procedure. Also, rarely, the catheter may damage a coronary artery. The risk of serious complications is small and is mainly in people who already have serious heart disease. As a consequence of serious complications, some people have died during this procedure. Your doctor will only recommend coronary angiography if they feel the benefits outweigh the small risk.