- if your coronary arteries are narrowed or blocked, and if so, where and how badly they are affected
- how well your heart muscle is working
- how well the heart valves are working
The results will help you and your doctor to decide if you need further treatment with drugs or surgery.
The procedure is usually performed as a day-case under local anaesthetic. This means that you will stay awake during the procedure. You may be offered a sedative to help ensure that you are relaxed and comfortable.
Your doctor will explain the benefits and risks of cardiac catheterisation, and will also discuss the alternatives to the procedure.
About the procedure
The procedure is usually carried out in a catheterisation room, which looks like an operating theatre. You will lie on a table and an X-ray machine will be positioned above your chest.
Before the procedure begins, you will have a small plastic tube (cannula) placed in a vein in the back of your hand. This is used to deliver sedatives, or other medicines if necessary, during the procedure. If you are having a sedative, you should start to feel relaxed and drowsy almost immediately.
You may be given oxygen to breathe through a mask. You will be given an injection of local anaesthetic in your groin or arm. This may sting but will quickly numb the area. Your doctor will make a small cut in this area (entry site) and thread the catheter through an artery and towards your heart.
Once the catheter is in the correct position, dye will be injected into the tube. You may feel a warm, flushing sensation or a fluttery heartbeat. You may also feel like you have urinated, but you won’t have done. This feeling is normal and passes quickly.
The X-ray machine takes pictures of the dye flowing through your blood vessels and heart, and sends these to a video monitor. Your doctor will watch this to see if there is any narrowing in the arteries or problems in the heart. You might be asked to cough or breathe deeply to help get better pictures. The procedure routinely takes around 20 to 30 minutes. A nurse will stay with you throughout to provide reassurance.
Afterwards, the catheter is removed. Your nurse will press firmly on your groin (or arm) for up to 20 minutes to seal the artery. Alternatively, a special device may be inserted to seal the artery. This will dissolve within 60 to 90 days.
Cardiac catheterisation is a commonly performed and generally safe procedure. For most people, the benefits of having a clear diagnosis are greater than any disadvantages. However, like all medical procedures, there is an element of risk.
Some people have an allergic reaction to the dye, which can cause an itchy rash that usually disappears quite quickly. Rarely the reaction can cause shortness of breath and a severe allergic reaction. If this happens, medicines are available to treat this.
It’s possible to get a wound infection and it’s also possible for blood vessels in the groin to be damaged causing heavy bleeding. This blood can accumulate internally and create a painful swelling called a haematoma. This can clear up by itself or may require surgery.
It’s also possible, but uncommon, for blood vessels leading to the heart to be punctured during the procedure. If this happens, you will need urgent surgery to repair the damage.
In rare cases, the tip of the catheter can dislodge a clot of blood or fatty plaque from the wall of a blood vessel. It’s possible for these to block an artery leading to the heart or brain, causing a heart attack or stroke.
Clots can also form near the cut, blocking blood flow to your arm or leg. If this happens, you may need surgery to restore circulation.
The chance of complications depends on the exact type of procedure you are having and other factors such as your general health. Ask your surgeon to explain in more detail how any risks apply to you.