Electrophysiology (EP) Study

What is an EP study?

A cardiac electrophysiology (EP) study is a test that is used to check if your heart's electrical system is working properly, and find out why if it is not.

Your heart’s electrical system coordinates your heart’s contractions to allow blood to flow normally and create a regular heartbeat or rhythm. This natural rhythm may be affected by many factors, leading to irregular heartbeat (arrhythmia). These factors include:

• Age
• Heart conditions such as high blood pressure
• A prior heart attack
• Congenital heart disease

To perform an EP study, thin electrodes are inserted into a vein and guided to your heart to measure its electrical signals. Your doctor may also use the electrodes to stimulate an abnormal heart rhythm and identify its cause. This information will help to determine an appropriate form of treatment.

Why do you need an EP study?

An electrophysiology (EP) study may be recommended to:

• Check for abnormal electrical signals that may be causing irregular heartbeats.
• Identify the source of an irregular heartbeat (arrhythmia).
• Investigate the cause of symptoms such as dizziness, fainting, weakness, or palpitations.
• Investigate your risk for cardiac arrest.
• Assess treatment options, which may include catheter ablation, a pacemaker or an implantable cardioverter defibrillator.
• Evaluate if a prescribed treatment is working.

Who should not undergo an EP study?

An EP study may not be recommended if you:

• Are pregnant
• Have problems lying still on your back for an extended period of time

Your doctor will advise if an EP study is the right procedure for you.

What are the risks and complications of an EP study?

An EP study may involve the following risks and complications:

• Bleeding, bruising or infection where the catheter is inserted into a vein.
• Blood clots at the end of the catheter(s), which may break off and block a blood vessel. To prevent this, your doctor may give you medicine.

Rarely, infection or damage to the heart or its electrical system may occur.

Note: As any current health condition may affect your risk, be sure to discuss your medical history and any concerns beforehand.

How do you prepare for an EP study?

You will need to provide your doctor with your medical history including:

• Medications, vitamins and supplements you are currently taking, especially any medicines that affect blood clotting (you will need to stop taking these a few days before the procedure).
• Any conditions that you may have, especially bleeding disorders.
• Allergies to any medications or substances, if any.

Depending on your existing health conditions, you may be asked to undergo some tests to confirm that you are healthy enough to undergo the procedure. You will also need to fast before the procedure. Your doctor may recommend fasting for 6 hours or overnight.

What can you expect in an EP study?

An EP study involves the insertion of thin, flexible electrodes into a vein. These electrodes are passed up to the heart to measure its electrical signals.

To reduce any discomfort during insertion, your doctor may numb the insertion site with a local anaesthetic or give you a sedative.

Estimated duration

Depending on the complexity of your arrhythmia, the test may take 30 – 60 minutes.

Before the procedure

Your doctor may apply a local anaesthetic to the insertion area, or give you a sedative. If the catheter will be inserted through a vein in your groin, you may need to shave the area.

You will also be connected to an electrocardiogram (ECG) monitor via small electrodes attached to your skin. The electrocardiogram will help to monitor your heart’s activity during the EP study.

During the procedure

Your doctor will:

• Insert the catheter after numbing the insertion site with a local anaesthetic.
• Guide the catheter to the specific heart chambers using fluoroscopy, a form of X-ray.
• Test different areas of your heart using small electrical impulses. During this time, you may feel your heartbeat stronger and faster than usual. If an abnormal heart rhythm is triggered, you may feel lightheaded and dizzy.

Depending on what the EP study reveals, the doctor may provide medication or issue an electrical shock to stop the arrhythmia. In some cases, you may require an ablation to destroy the small, abnormal part of your heart muscle that is causing the irregular heartbeat.

If you feel pain in your chest, neck, jaw, arm or back, or have difficulty breathing, tell your doctor immediately.

After the procedure

Your doctor will remove the catheters and apply a bandage to stop the bleeding. The medical team will observe your condition and recovery.

If the catheter was inserted via your groin, you will not be able to move your leg for several hours. You will be told when you can leave your bed. Be careful to move slowly at first to avoid dizziness. Your doctor will advise when you are ready to be discharged.

Care and recovery after an EP study

Take care to avoid strenuous activities for a few days, and follow your doctor’s advice on when you can resume normal activity. Once at home, take note of any:

• Abnormal bruising colour
• Signs of bleeding
• Unusual pain
• Swelling
• Fever

Contact your doctor immediately if you experience any of the following:

• Fever with a temperature higher than 38°C.
• Increased pain, redness, swelling, bleeding or other drainages where the catheter was inserted. A small bruise is normal, but a large amount of blood is not.
• Changes in the affected leg, such as coolness, numbness or tingling.
• Chest pain or pressure, nausea or vomiting, profuse sweating, dizziness, or fainting.