Electrophysiology Study (EPS)

By Medically reviewed by hellodoktor


What is Electrophysiology Study (EPS)?

An electrophysiology study (EPS) is a test used to understand and map the electrical activity within your heart. It involves placing diagnostic catheters within your heart and running specialized tests to map the electrical currents.

Why is Electrophysiology Study (EPS) performed?

The purpose of Electrophysiology Study (EPS) is to determine:

  • Where an arrhythmia is coming from.
  • How well certain medicines work to treat your arrhythmia.
  • If a problem should be treated by destroying the place inside your heart that is causing the abnormal electrical signal. This procedure is called catheter ablation.
  • If a pacemaker or implantable cardioverter defibrillator (ICD) might help you.
  • If you are at risk for heart problems such as fainting or sudden cardiac death due to cardiac arrest (when your heart stops beating).

Your doctor may recommend an EP study if you:

  • Have an abnormal heart rhythm (arrhythmia). If you’ve been diagnosed with an arrhythmia, such as atrial fibrillation, atrial flutter, tachycardia, ventricular tachycardia or supraventricular tachycardia, your doctor may recommend an EP study to better understand how electrical signals move in your heart and how best to treat your condition.
  • Are undergoing cardiac ablation. An EP study is done at the beginning of a cardiac ablation procedure for arrhythmia. Cardiac ablation uses heat or cold energy to create scar tissue in the heart to block erratic electrical signals.
  • Experience a temporary loss of consciousness (syncope). People who experience syncope may undergo an EP study to understand the cause.
  • Have a risk of sudden cardiac death. If you have a heart condition that increases your risk of sudden cardiac death, an EP study may help your doctor better understand your risk.
  • Are undergoing heart surgery. If you’re preparing for a heart operation in which cardiac ablation may be performed at the same time, your doctor may recommend an EP study.


What should I know before receiving Electrophysiology Study (EPS)?

The puncture site may be sore for several days. A small bruise at the puncture site is normal. If the site starts to bleed, lie flat and press firmly on top of it. Have someone call the doctor or EP lab.

An EPS carries a risk of complications, including:

  • Bleeding or infection at the site where your catheter was inserted
  • Damage to your blood vessels where the catheter may have scraped as it traveled to your heart
  • Puncture of your heart
  • Damage to your heart valves
  • Damage to your heart’s electrical system, which could worsen your arrhythmia and require a pacemaker to correct
  • Blood clots in your legs or lungs (venous thromboembolism)
  • Stroke or heart attack
  • Death in rare cases


How to prepare for Electrophysiology Study (EPS)?

You’ll need to stop eating and drinking the night before your test. If you take any medications, ask your doctor if you should continue taking them before your test.

Your doctor will let you know if you need to follow any other special instructions. In some cases, you’ll be instructed to stop taking medications to treat a heart arrhythmia several days before your test.

If you have an implanted heart device, such as a pacemaker or implantable cardioverter-defibrillator, talk to your doctor to see if you need to take any special precautions.

What happens during Electrophysiology Study (EPS)?

EPS usually last 1 to 4 hours. Then, you’ll be moved to a recovery room where you should rest quietly for 1 to 3 hours.

At a hospital or clinic, doctors and nurses do EPS in a room that has special equipment for the tests. You may hear this room called the electrophysiology laboratory, or EP lab. Some call it the catheterization laboratory (cath lab). During the test:

  • A nurse will put an IV (intravenous line) in your arm. You’ll get medicine (a sedative) that will help you relax. But you’ll be awake and able to follow instructions during the test.
  • Your nurse will clean and shave the part of your body where the doctor will be working. This is usually in the groin but may be the arm or neck.
  • You’ll be given a shot – a local anesthetic will be given — to make the area numb. Your doctor will make a needle puncture through your skin and into your blood vessel. A small straw-sized tube called a sheath will be inserted into your artery or vein. The doctor will gently guide several specialized EP catheters into your blood vessel through the sheath and advance them to your heart. A video screen will show the position of the catheters. You may feel some pressure in the area where the sheath was inserted, but you shouldn’t feel any pain.
  • Your doctor will send small electric pulses through the catheters to make your heart beat at different speeds. You may feel your heart beat stronger or faster.
  • Electrical signals produced by your heart will be picked up by the special catheters and recorded. This is called cardiac mapping and allows the doctor to locate where arrhythmias are coming from,
  • Your doctor will remove the catheters and the IV line. Your nurse will put pressure on the puncture site to stop any bleeding.

If the type and location of the arrhythmia is identified and an appropriate therapy decided, cardiac ablation or insertion of a pacemaker or ICD may be performed during or immediately after the EPS.

What happens after Electrophysiology Study (EPS)?

Following your EP study, you’ll be moved to a recovery area to rest quietly for four to six hours to prevent bleeding at your catheter site. Your heartbeat and blood pressure will be monitored continuously to check for complications.

If you have any questions about the Electrophysiology Study (EPS), please consult with your doctor to better understand your instructions.

Explanation of results

What do my results mean?

Normal EPS results show that the heart initiates and conducts electrical impulses within normal limits.

Abnormal results include confirmation of arrhythmias, such as:

  • Supraventricular tachycardias
  • Ventricular arrhythmias
  • Accessory pathways
  • Bradycardias

Depending on the laboratory and hospital, the normal range for Electrophysiology Study (EPS) may vary. Please discuss with your doctor any questions you may have about your test results.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: October 12, 2018 | Last Modified: September 12, 2019

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