Electrophysiological study


An electrophysiological study (EPS) is performed to examine the mechanism of the heart rhythm abnormality. The results of this study may help the Electrophysiologist determine the appropriate treatment of the arrhythmia, which may include ablation.

How do I prepare for EPS?

  • Do not eat or drink anything 4-6 hours before the test.
  • Tell your Electrophysiologist and/or specialist nurse about any medicines you take as you might be asked to stop them before the EPS. Do not stop taking your medicine unless instructed by your Electrophysiologist.
  • Have someone drive you to your appointment and take you home.
  • If you usually wear a hearing aid, wear it during the procedure. If you wear glasses, bring them along to your appointment.

How is EPS performed?

A nurse will check your blood pressure, pulse and oxygen levels. A small sample of blood may be taken to ensure it is not too thin and to ensure the procedure can be undertaken as safely as possible. A small tube (cannula) will be inserted into a vein in your arm so that you can be given sedation and other drugs.

You will then be taken to the cardiac catheter lab for the procedure. You will generally be awake throughout the procedure and will be given a local anaesthetic and a sedative. You will need to lie flat during the procedure. You will be asked to lie as still and relaxed as possible.

Up to four small tubes will be inserted through a vein in your leg. Through these, electrically sensitive catheters are placed inside the heart to record electrical activity using X-ray guidance. These catheters also enable the Electrophysiologist to pace the heart at different rates, thus examining how the arrhythmia behaves. Pacing the heart is painless but may sometimes make you feel uncomfortable in the chest or bring on your palpitations. This will assist the Electrophysiologist to make a diagnosis of your arrhythmia. Normal rhythm can be restored promptly by the Electrophysiologist by pacing the heart.

Electrophysiology Study.

Although most arrhythmia circuits can be identified with X-ray guidance and electrical catheters, some more complex arrhythmias are better located using a 3-dimensional mapping system, which works like GPS navigation within the chest and heart. Irrespective of the specific technology used, the procedure is similar from the patient's viewpoint.

3 dimensional navigation system for ablation of atrial fibrillation from Biosense Webster.

The procedure usually takes an hour to perform. If ablation is the most appropriate treatment option and your Electrophysiologist discussed this with you prior to the EPS, it is likely that ablation will be undertaken immediately after the EPS using the same tubes in your veins in your groin to access the heart.

What are the risks?

An EPS is a very safe test and the likelihood of a complication is less than 0.5%.

These rare risks include:

  • Blood vessel problems: bleeding, bruising, damage to the vessel wall, abnormal connections and blood clots can form in the blood vessel in your groin or higher up near the heart. Usually these settle by themselves, but sometimes medications, injections or small operations are required to fix them.
  • Abnormal heart rhythms: these are deliberately provoked during the procedure, but can become unstable requiring an electric “shock” to restore a normal heart rhythm.
  • Perforation: there is a very small chance of causing a leak of blood around your heart. This usually settles without treatment but can also be dealt with by inserting a drain from the chest wall.

What happens after EPS?

You will be required to lie flat for 1-3 hours. During this time, your nurse will check on you to see if there is bleeding or swelling at the groin site. Most patients go home the same evening of their procedure unless ablation is performed. Your Electrophysiologist may stop, switch or commence you on new medications after the procedure. You may receive a blood-thinning medication as an injection in your belly for a few days.

Most people can start eating and drinking water within 4-6 hours after the procedure. Most can resume their daily activities the day after but you should not drive for at least 48 hours. If you have received ablation, you might not be allowed to drive for a longer period of time.

Your groin site might be sore for several days. A small bruise at the groin site is normal but if it starts to bleed, contact your local doctor or the Electrophysiologist.