Coronary angiography is used to show where any narrowing in the coronary arteries is and how severe they are. Coronary angiography is a small surgical procedure, which is done under local anaesthetic. It takes between 20 - 60 minutes to do. Most people have it done as a day case, although some people will need a short stay in hospital.

The day before you come into hospital you will need to shave the areas from which the test may be performed, either your groin or right wrist.

On the morning of the procedure please take a shower or bath as this will help reduce the risk of infection.

You should not eat for four hours before the procedure but may have clear fluids ie. black tea, black coffee or water up to the procedure.

The test takes place in a room called a cardiac catheterisation laboratory. It contains special x-ray and recording equipment. There will always be a nurse available to explain what is happening.

While you are having the procedure you will be linked to a heart monitor, which records your heart rate and rhythm. Your blood pressure will also be monitored throughout the procedure.

A catheter is a long flexible hollow plastic tube about the width of the lead in a pencil. It is passed into an artery either in the groin or the wrist. You will have a local anaesthetic to numb the area where the catheter is put in, so it should not be painful. Then a half centimetre cut is made in the skin either in the wrist or groin.

An introducing tube called a sheath is placed into the artery in the groin or wrist. The catheter is then inserted through this sheath into the artery. The doctor uses x-ray screening to help direct the catheter through the blood vessels and into the correct position in the heart. You will not feel the catheter moving around inside your chest. You can watch the procedure on the video screen if you want to.

When the catheter reaches the entrance to the coronary arteries, which lie on the surface of the heart a special fluid (contrast dye), which shows up on xrays is injected into the coronary arteries through the catheter. X-ray films are taken when the contrast dye is in the arteries and any narrowing and blockages within the coronary arteries are recorded. Contrast dye can also be injected into the left side of the heart to assess the pumping action of the heart. The contrast dye can sometimes cause a hot flushing sensation, which lasts a few seconds. You will be warned to expect this.

You may notice a warm feeling in your groin and may think you have wet yourself, even though you have not. People occasionally feel their angina pain during the procedure. This does not mean anything is going wrong but you should tell the doctor about the pain.

While the x-rays are being taken the x-ray machine will move around and will come close to your head and chest but it won’t touch you. This allows different views of the heart to be seen. You must lie flat with one pillow and you must try and keep still during the procedure.

When the procedure is finished the catheter is removed. If the procedure has been done from the artery in the wrist a pressure device will be applied immediately to the puncture site to stop the artery bleeding and allow a clot to form and heal the artery. You may move around immediately if the medical and or nursing staff are happy with your condition.

If the procedure has been done from the artery in the groin an introducing tube called a sheath will be left in the artery in the groin and this will be removed on the ward by a nurse who will then apply a pressure device to stop the artery bleeding and allow a clot to form and heal the artery.

With this approach you will be on bed rest for approximately two hours unless there are problems with bleeding. If your leg is satisfactory after two hours you will be allowed up to move around the ward. A nurse will help you to your feet when you first get out of bed as occasionally you may experience numbness in the leg if a lot of local anaesthetic has been used. In situations like this you will be advised not to walk until the anaesthetic has worn off, which may take several hours.

You may feel some tenderness in your groin or wrist but this should ease over the next 24 hours. A nurse will examine your groin or wrist several times after the procedure and before discharge to check for any possible bleeding or swelling. The pulses in the leg or arm will also be checked regularly to ensure the blood supply has not been affected.

You will be able to eat and drink as normal after the procedure. You will be encouraged to drink plenty to help the contrast dye pass through your body as quickly as possible. It is passed out through your urine but it is colourless so you will not notice it.

It should be stressed that this procedure is very common. Serious complications are rare, but it would be wrong to give the impression that procedures such as this can be carried out without any risk at all, especially if you have serious heart disease.  The risks usually quoted are:

• 1 in 1000 of a heart attack, stroke or death.
• 1 in 200 of being allergic to the contrast dye.
• 1 in 200 of having a local vascular complication i.e. damage to the artery in the groin, which will need to be repaired.

Bleeding or bruising at the puncture site in the artery in the groin or wrist may also occur. If the procedure is done from the artery in the wrist there may be discomfort if the artery goes into spasm. In order to reduce the risk of this happening an antispasmodic drug is given into the vein at the beginning of the procedure. There is also a small risk of a thrombus (blood clot) forming in the artery in the arm, but it should be stressed that serious complications requiring treatment are very rare. As there are two arteries in the arm, should there be a problem with the artery used for the procedure the other artery will be able to adequately supply the arm with blood.

It should also be stressed that these risks are more likely to occur while you are in hospital and still under medical supervision. If your individual risks differ from those listed above you will be advised of this long before the procedure.

To find out more about this or any other treatments and procedures log onto the British Heart Foundation website.