Electrophysiology (EP) Study

An electrophysiology (EP) study is often done in concurrence with a catheter ablation.  The EP study is done when a problem arises affecting the heart’s electrical system and causes an abnormal heart rhythm (arrhythmia), or heart rhythm disturbance.  The EP study will map the electrical activity of the heart and pinpoint the source of the abnormal heart rhythm.  A catheter ablation will subsequently be done to fix the problem and relieve the symptoms.  A catheter ablation is called upon when medications to control the abnormal heart rhythm do not work or present too many side effects.


Pre-Test Procedures

  1. The EP study will be done in the EP lab at St. Boniface Hospital.
  2. The doctor will explain the risks and benefits of the procedure.  After all of your questions have been answered, you will be asked to sign a consent form.

Test Procedures – EP – 45 minutes

  1. The hair in your groin area will be clipped for the insertion of the catheter.
  2. You will have a needle put into a vein (intravenous) to give any fluids or medications.
  3. Medications will be given to help you relax.  If you are feeling anxious at any time, tell the nurse, where the nurse will monitor your comfort.  All staff will be wearing gowns, masks and special lead aprons.
  4. Most cases are performed with conscious sedation.  This means that you will be given medications to put you at ease and to make you drowsy.  You may sleep through the procedure, although most patients are awake through parts of it.  In certain cases, you may be put under general anesthesia.  This means that you would be asleep for the procedure, with a breathing tube inserted to help control your breathing.  You may also have a special ultrasound probe inserted to carefully watch the heart during the ablation. 
  5. The doctor will numb the area around your groin.  Once the area is numb, small special catheters (flexible tubes) will be inserted there.  Anywhere from three to five catheters will be inserted through the tubes and threaded up to your heart.
  6. In a large number of cases, X-rays will be taken during the procedure to help make sure the tubes are in the right place.  During the placement of the tubes, you may feel some pressure in your groin and some palpitations. 
  7. When the catheters are properly placed, recordings and measurements of the electrical activity in your heart will start.  The doctor will pace your heart at different speeds to try and start your abnormal heartbeat.  You may also receive medications to start the abnormal heartbeat.
  8. The goal is to learn about the exact nature and location of your abnormal heartbeat.

Test Procedures – Catheter Ablation – 1-4 hours

  1. A special ablation catheter is placed in your groin.  The tip of the catheter is directed to the part of your heart that is causing the abnormal heart beat, which treats the tissue in your heart causing the abnormal heartbeat.
  2. Once the procedure is completed, the catheters are removed and the doctor or nurse will apply pressure to your groin until there is no bleeding from the puncture sites.

Post-Test Procedures

  1. You will be brought to a special area to recover where you will rest in bed for 2-4 hours.  It is stressed that you lay flat and keep your legs straight.  Reminders will be given from the nurse to ensure bleeding does not occur at the groin.
  2. Someone will help you stand the first time you get up, and a snack will be provided once the sedation has worn off.
  3. Inform your nurse right away if you notice any swelling or bleeding in your groin, back discomfort, chest discomfort or difficulty breathing.  Please note that there may be bruising or discoloration at the groin site.  A certain amount of bruising, stiffness, soreness, or numbness at the groin is expected.
  4. A small bruise or lump is normal and will likely go away on its own.  Do not massage or rub the site.
  5. You may be discharged the same day of your procedure or remain in the hospital overnight.

Patient Instruction


  • You will need a ride home and have someone stay with you for the first 24 hours after you leave the hospital. 
  • If you live greater than 1.5 hours away from St. Boniface Hospital, please arrange to stay in Winnipeg for the 24 hours after leaving the hospital.

Mandatory Pre-Test Measures

  • You will receive a telephone call from the EP Nurse Coordinator with a date and time to meet with the nurse before your procedure, and a date and time for your procedure.  A telephone appointment with the nurse will take place approximately two weeks before the procedure. Current bloodwork will be required.
  • This appointment will be 45 minutes long. During this appointment, we will review your history, will review your medications, and will teach you about your upcoming ablation procedure.
  • During this appointment, you will be given specific instructions about your medications, so it is a good idea to have a pen and paper available to write down the information. If you have a speaker phone, it is a good idea to have someone else present to hear the information.

Additional Info

EP studies and ablation procedures are fairly safe; however, it is important to be aware of some rare and very rare complications:

  • Rare complications including excess bleeding, bruising, or swelling where the catheters were placed.
  • Very rare complications include a hole poked into the heart, a change to the heart’s electrical system which may result in the need for a pacemaker, a blood clot in the vein, a heart attack, or a stroke.
  • Contact Info – 204-258-1409

A Guide for Patients and Families (English)
A Guide for Patients and Families (French)

VIDEO: A Guide to Your Electrophysiology (EP) Study or Catheter Ablation

Temporary Directions to the Y2 Bergen Cardiac Care Centre