It is usually done to investigate abnormal fast heart rhythms. This can include atrial flutter or atrial fibrillation, supra-ventricular tachycardia (SVT) or ventricular tachycardia (VT). If you have been found to have one of these rhythms your medical team may recommend that you have an EP study.

Sometimes your team may recommend an EP study even in the absence of symptoms, if they think you are at high risk of abnormal heart rhythms, for example to help decide if you should have a internal cardiac defibrillator (ICD).

EP studies in ACHD patients are specialised procedures because the heart rhythms that are seen in ACHD patients can be different to those seen in other people.

For this reason your cardiology team will often recommend that the procedure be done in Auckland by an electrophysiology doctor who has particular training and expertise in abnormal heart rhythms in ACHD patients.

Some people will need to have a general anaesthetic if the procedure is expected to be quite long. The potential downside to this is that abnormal fast heart rhythms may be less likely to happen when you have a general anaesthetic, so this needs to be weighed up before you have the procedure.

Alternatively you may be given a sedative medicine to help you relax during the procedure. This will be discussed with you prior to your EP study.

The EP study is carried out in a cardiac catheterisation room. This is a sterile room with specialised monitoring equipment that allows very detailed analysis of the electrical signals that trigger the heart beat.

Thin flexible tubes called catheters are inserted into a vein, usually in the groin. You’ll have a local anaesthetic injection to numb the area where the catheters are put in. This vein connects up to your heart, so the catheters can be passed up into your heart.

When the catheters are inside your heart they can be used to build up a very detailed picture of the tiny electrical signals that generate the heart beat. They can also be used to induce an abnormal heart rhythm like the one that you have been experiencing.

Once the abnormal rhythm has been detected and analysed, the electrophysiology team can work out the best way to try to get rid of the abnormal heart rhythm. This usually involves a procedure called ablation, where heat energy or freezing energy is applied to the inside of the heart via a special type of catheter. The idea is to destroy the small area that is causing the abnormal rhythm, so that it cannot happen again in the future.

The risk of major complications is low, but varies a bit depending on the exact heart condition that you have and what sort of heart rhythm you have been experiencing. The electrophysiology doctor will talk to you about this in more detail before you give your consent to have the test.

More common complications include bleeding from the area where the catheter was put in, usually in your groin. Some people can develop a collection of blood under the skin, called a haematoma. This can be uncomfortable and will cause bruising, but should settle after a few days.

If you have an ablation procedure the aim is to destroy the area causing the abnormal heart rhythm, but there is always a small risk of damage to your heart’s normal electrical pathways. If this happens, you may need to be fitted with a pacemaker. In general this happens in about 1 in 200 people who have an ablation procedure.

If you are taking heart rhythm medicines, you will usually need to stop these prior to the procedure. Often this will be 4-5 days before the procedure, but you will be told the exact timing when your admission for the EP study is arranged.

On the day of the procedure you’ll usually be asked not to eat or drink anything for a few hours beforehand.

Most people will come into hospital the day before the procedure and go home the day after. So usually 2 nights in hospital, although this can vary in some cases.