Electrophysiology Test

An electrophysiology study is an invasive test your provider uses to examine the electrical signals happening in your heart. Catheters or tubes that go through a vein and into your heart help your provider see where abnormal heart signals start. This helps them diagnose your arrhythmia, or abnormal heart rhythm, and decide on a treatment.


What is an electrophysiology study?

An electrophysiology (EP) study is a detailed evaluation of the electrical activity in your heart. Your healthcare provider uses cardiac catheters (small tubes) and computers to make electrocardiogram (EKG) tracings and electrical measurements from inside your heart.

Studying your heart’s electrical activity can tell your provider where something is going wrong with your heartbeat signals. Normally, signals that tell your heart to beat travel the same route in an organized way every time.

When you have an abnormal heart rhythm, it’s like a bus that isn’t following its normal route. The bus may start the route at the wrong bus stop, skip a stop or not travel the full route, for example. Or it could be going too fast or too slow. Irregular signals can be like this and your provider wants to find out why.


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How does an electrophysiology study work?

During your electrophysiology test, your cardiologist may safely reproduce your abnormal heart rhythm (also called arrhythmia or dysrhythmia). Then they’ll give you medications to see which one works best to control your irregular rhythm.

Why is an electrophysiology study done?

Your electrophysiological study can give your healthcare provider information about your abnormal heart rhythm such as:

  • What’s causing your abnormal heart rhythm.
  • Why you’ve been fainting.
  • Where in your heart your abnormal heart rhythm starts.
  • Which treatment is best for you.
  • How well your medicine is working.
  • Whether you may be at risk for sudden cardiac death.

Your provider may recommend an electrophysiology study when other tests can’t provide enough information to thoroughly evaluate your abnormal heart rhythm.

You may have already tried these tests:


Test Details

How do I prepare for an electrophysiology study?

You can prepare for your electrophysiology study in these ways:

  • Make plans to have someone drive you to and from the hospital. You won’t be able to drive until at least 24 hours after your test.
  • Talk to your healthcare provider if you have any questions or concerns about your procedure.
  • Tell your provider if you’re allergic to latex or have trouble with anesthesia.


Follow these medication tips when preparing for your electrophysiology study:

  • Tell your healthcare provider what you’re taking, including prescription medicines and the kind you buy without a prescription. This includes herbs and supplements.
  • Ask your provider which medications you should take or stop taking before the procedure.
  • Stop taking certain medications one to five days before your test.
  • Don’t stop taking any medication without consulting with your doctor.
  • If you have diabetes, check with your provider about how to adjust your diabetes medication(s).
  • Bring a one-day supply of your prescription medications to your appointment. Don’t take these medications until you talk with your provider first.

Eating and Drinking

Prepare for your electrophysiology test in these ways:

  • Eat a normal meal the evening before your procedure.
  • Don’t eat, drink or even chew anything after midnight before your test. This includes gum, mints and even water.
  • If you must take medications, only take them with small sips of water.
  • When brushing your teeth, don’t swallow any water.

Clothes, Jewelry and Makeup

Guidance on what you should wear on the day of your electrophysiology test:

  • Wear comfortable clothes. A healthcare provider will return them to the person who brought you to the hospital.
  • Remove all makeup and nail polish before you come to the hospital.
  • Leave all jewelry (including wedding rings), watches and valuables at home.
  • Wear your glasses and hearing aids if you have them.

What to expect on the date of an electrophysiology study

Your study will take place in a special room called the electrophysiology laboratory, EP lab or catheterization lab.

After you lie in a bed, your healthcare provider will:

  1. Start an IV (intravenous line) in a vein in your arm or hand. The IV will send medications and fluids into your body during your procedure.
  2. Shave your groin, arm or neck if needed and clean it with an antiseptic solution.
  3. Cover you with sterile drapes from your neck to your feet.
  4. Place a strap across your waist and arms to prevent your hands from coming in contact with the sterile area.

Are you awake during an EP study?

You’ll receive medication through an IV (intravenous line) to help you relax and make you feel drowsy. However, you won’t be asleep during your electrophysiology test.

How long does an electrophysiology study take?

The EP study takes one to four hours.

How is an electrophysiology test done?

Your healthcare team will use several monitors so they can check your heart rhythm and blood pressure throughout your procedure.

  • Fluoroscopy: A large X-ray machine positioned above you helps your healthcare provider see the catheters on an X-ray screen at all times during your procedure.
  • Defibrillator/pacemaker/cardioverter: This connects to one sticky patch placed on the center of your back and one on your chest. This allows your provider to pace your heart rate if it’s too slow, or deliver energy to your heart if the rate is too fast.
  • Electrocardiogram (EKG): This connects to several sticky electrode patches placed on your chest, as well as inside your heart. It provides a picture of the electrical impulses traveling through your heart.
  • Blood pressure monitor: This connects to a blood pressure cuff on your arm and checks your blood pressure throughout your EP test.
  • Oximeter monitor: This is on a small clip placed on your finger. It checks your blood’s oxygen level.

Electrophysiology study basics

Your healthcare provider will:

  1. Numb your groin, neck or arm with a special medication.
  2. Insert several catheters (narrow tubes) into a vein in your groin, neck or arm.
  3. Use the fluoroscopy machine to guide the catheters to your heart and into each of its chambers. The catheters sense and record the electrical activity in your heart, which helps your provider evaluate your heart’s conduction system.
  4. Use a pacemaker to give your heart electrical impulses through one of the catheters to increase your heart rate. You may feel your heart beating faster or stronger.
  5. Use catheter ablation to damage abnormal electrical connections that cause irregular heartbeat signals.

Tell your provider about any symptoms you feel during your electrophysiology study. If an abnormal heart rhythm happens, your provider may give you medications through your IV to test their effectiveness in regulating it. If you need it, your provider can send a small amount of energy through the patches on your chest to bring your heart back into a normal rhythm.

Is an electrophysiology study painful?

You shouldn’t feel pain during your EP study because you’ll receive medicine to keep you comfortable. However, you might feel pressure where the catheters went into your skin.

What to expect after an electrophysiology study

After your electrophysiological study, your healthcare provider will remove the catheters from your groin, arm or neck and apply pressure to the site to prevent bleeding. You’ll:

  • Stay in bed for one to three hours after your test and keep your leg as still and straight as you can (if the catheters were in your groin).
  • Have a small sterile dressing that you can remove the next day. You won’t need stitches.
  • Keep the incision area clean and dry.
  • Stay in the hospital if necessary, depending on your preliminary test results.
  • Be able to eat and take medicine four to six hours after your test.
  • Get back to your normal activities the day after your test.

What are the risks of an electrophysiology study?

An electrophysiology test is generally a very safe procedure. However, as with any invasive procedure, there are risks. These may include:

  • Infection where your healthcare provider put in the catheter.
  • Bleeding where your provider put in the catheter.
  • An abnormal heart rhythm.
  • A blood clot can start on the catheter, get into a blood vessel and block it.
  • Injury to a blood vessel, heart valve or heart chamber.
  • Heart attack.
  • Stroke.

Cardiologists and nurses who specialize in electrophysiology will perform the procedure in the controlled environment of an electrophysiology laboratory. They’ll take special precautions to decrease these risks.

Talk to your provider about any concerns you may have about the risks and benefits of the procedure.

Are electrophysiology studies safe?

Yes, electrophysiology studies are safe. The risk of an EP study being fatal is one in 5,000.

Results and Follow-Up

What type of results do you get and what do the results mean?

Your healthcare provider will explain the type of abnormal heart rhythm you have and how to treat it. They’ll also decide if you need treatment for your abnormal heart rhythm, which may include:

Your provider may decide to give you some of these treatments during or right after your electrophysiology study.

When should I know the results of an electrophysiological study?

You’ll get preliminary test results after the procedure. Based on these results, your healthcare provider will decide if you can go home or will need to stay in the hospital. They may want you to make an appointment with them to talk more about your electrophysiology study results and treatment.

When should I call my doctor?

Contact your doctor if you have:

  • Redness, swelling or drainage at the incision site.
  • Numbness or tingling in your arm or leg that has the incision.
  • A cold feeling or color change in your hand or foot.

Call 911 instead of your doctor if you have:

  • Bleeding that continues after you put pressure on your incision.
  • Swelling that gets worse without warning around your wound.

A note from Cleveland Clinic

Having an electrophysiology study may seem like a bigger deal than the other heart tests you’ve had, but your healthcare provider scheduled it for a reason. They want to find out what’s happening in your heart so they can help you. Although an electrophysiological study is invasive, it’s a safe test that will give your provider the information they need to fix your abnormal heart rhythm. Your healthcare team will make sure you’re comfortable during your electrophysiology test.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 05/13/2022.

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