Sometimes it is not possible to make important decisions about a patient’s treatment unless a test called a cardiac catheterisation (sometimes referred to as coronary angiogram or a dye test) is done. This is especially true if you have angina and your doctor wants to find out if surgery will help you.
What can the test show?
The cardiac catheterisation test gives vital information about the blood pressure inside your heart, and how well the pumping chambers and valves are working. Most importantly, it is also used to show where any narrowings in the coronary arteries are and how severe they are.
The test is done in an X-ray room and takes between 20 minutes and an hour. You should not eat 3-4 hours before the test but should continue to drink clear fluids. Most people have the catheter test as a day case. However, some people will need a short stay in hospital. A catheter is a long, flexible, hollow plastic tube. It is passed into a vein or artery either at the wrist or occasionally the groin. You will have a local anaesthetic to numb the area where the catheter is put in, so it should not be painful. The operator then 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, but you may be aware of the occasional ‘missed’ heartbeat or ‘extra’ beat. While you are having the catheterisation, you will be linked to an ECG recorder which records your heart rate and rhythm. This will be checked continuously. The blood pressure at the tip of the catheter will also be checked.
X-ray films are taken by putting a fluid down the catheter and taking a series of pictures called angiograms. People occasionally feel a short, mild angina pain during the test. This does not necessarily mean anything is going wrong, but you should tell the doctor about the pain. With some pictures which are occasionally needed, the fluid may cause a hot flushing sensation for a few seconds and you may think you have passed water, even though you have not. You will be warned when to expect this.
When the test is over, the catheter is removed. If the catheter was inserted via your wrist, an inflatable pressure bandage will be applied for a few hours. If the catheter was inserted via your groin, a special plug may be inserted or pressure applied for about 20 minutes. A nurse will examine your wrist or groin several times after the test, to check for any possible bleeding. The place where the catheter was inserted may be tender for a few days. Most people get back to normal after a day or two, but this varies from one person to another.
Is there any risk?
The first doctor to perform a cardiac catheterisation did it on himself. Since then millions of these tests have been done. The most common after-effect is some bruising or swelling around the puncture site. This normally resolves over 1-2 weeks, but if it becomes progressively painful or swollen you should contact the cath lab at Craigavon or 1 North if out of hours ward so that the puncture site can be checked. Reaction to the contrast (dye) is unusual but do let your doctor know if you have had an allergic reaction to shellfish or to xray dye tests in the past. Serious complications are rare. In particular, the risk of life-threatening complications such as heart attack or stroke is less than 1 in 1000 patients. It would be wrong to give the impression that investigations such as this can be carried out on patients, some of whom may have serious heart disease, without any risk at all, but your doctor will not recommend a catheterisation test unless he or she feels that the benefits outweigh this very small risk. If you have any worries you should discuss these with a doctor before the test.
Depending on the results of your tests, you may be advised to take medicines, to have ‘angioplasty or stenting’, or to have heart surgery. You will be able to discuss this with your cardiologist or doctor. If it is the first time you have been diagnosed with heart disease it may come as a shock to you. It is natural to feel anxious about what the news means for you, your family life and your work. Information can be a great help. If you have questions it is important you are given explanations you understand. If an answer isn’t clear, it’s OK to say: “I don’t understand that. Could you explain it again please?"