Electrophysiological (EP) studies

Doctor and monitors

Electrophysiological (EP) studies allow your doctor to look at your heart's electrical activity in finer detail.

This test has revolutionised the way we understand and treat fast or abnormal heart rhythms.

Sometimes your doctor will also carry out a catheter ablation - a treatment that can help control or correct an abnormal heart rhythm - during this procedure.

How is an EP study done?

  • The test usually takes about 2-3 hours, but can sometimes take longer.
  • The hospital will ask you not to eat or drink anything for a few hours beforehand.
  • Thin flexible tubes, called catheters, are inserted into a blood vessel, usually in the groin. You will have a local anaesthetic injection which numbs the area where the catheters are put in. You may also be given sedation to help you relax during the procedure.
  • The catheters are moved into the position in the heart, where the special electrode tip stimulates the heart and records the electrical activity.
  • This may make you feel as if you are having palpitations and can make some people feel dizzy. You should tell the staff if you experience any symptoms. You may also feel a sensation or discomfort in your chest, but this should not be painful.
  • During the test you are continuously monitored by the nurses, doctors and technicians carrying out the procedure.

What happens after the test?

When the test is over, the catheters are removed. Sometimes there may be a small amount of bleeding when they are taken out. A nurse or doctor will press on the area for a short while to stop any bleeding.

You will be asked to stay in bed for a while afterwards.

The test is sometimes done as a day case. However, some people will need to stay in hospital overnight.

You may feel tired afterwards, but you should feel back to normal within a few days.

What can the test show?

An EP study can diagnose abnormal heart rhythms and identify which areas are affected.

Abnormal heart rhythms often happen during the test. These can help with the results of the test but sometimes may need to be treated during the EP study.

If the cause of your abnormal heart rhythm is found, the doctor will sometimes want to treat the problem during the test by using catheter ablation. This treatment uses either heat (radio-frequency ablation) or freezing (cryogenic ablation) to destroy the areas inside the heart which are causing the abnormal rhythm.

If you have an abnormal heart rhythm, an EP study can also show how well your medication is controlling your condition.

Are there any risks?

An EP study does involve a very small amount of risk. Your doctor will explain this to you before you give your consent to have the test.

If there is bleeding from the area where the catheter was placed, you might develop a collection of blood under the skin, which is called a haematoma. It can be uncomfortable and cause bruising, but this should go down after a few days. However, contact your doctor if you have any concerns.

There is a small risk of damage to the heart's normal electrical pathways. If this happens, you may need to be fitted with a pacemaker.

Your doctor will only recommend that you have an EP study if he or she thinks the benefits outweigh the risks.

Our scientists are helping to beat heartbreak

Your donations help us fund more pioneering research into improving our understanding of heart rhythms, such as Professor David Eisner’s work at the University of Manchester.

We're finding new, better treatments for people with heart and circulatory diseases, and developing new ways to better prevent or diagnose them.

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Want to know more?

Order or download our publications:

Tests booklet



Pacemaker booklet



Heart rhythms booklet

Heart rhythms