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Electrophysiological Study (EPS)

What is EPS?


Electrophysiology studies (EPS) are tests that help doctors to understand the nature of abnormal heart rhythms (arrhythmias).

These results are then read to help you and your doctor to form a course of treatment i.e. if you need medicine, a pacemaker, an implantable cardioverter defibrillator (ICD), cardiac ablation or surgery. 

Who needs it?

EPS is done when someone’s heart does not beat normally. Certain groups of people may have a higher chance of abnormal heart beats. These groups may include:


  • Someone who has suffered an heart attack;

  • Older people;

  • People with high blood pressure

What happens during EPS?


  • These studies take place in an electrophysiology (EP) lab or catheterization (cath) lab.

  • An IV (intravenous line) will be inserted in your arm to receive a medicine that will help you relax ( eg, a sedative), but awake and able to follow instructions during the test.

  • Cleaning and shaving of the body part where your doctor will be working on will be done (This is usually in the groin but may be the arm or neck).

  • After local anesthesia, your doctor will make a needle puncture through your skin and into your blood vessel. A small fine tube, called a sheath, will be inserted into your artery or vein. Special EP catheters will then be guided into your blood vessel through the sheath and advanced to your heart. A video screen will show the position of the catheters. 

  • Since small electric pulses will be sent through the catheters to make your heart beat at different speeds you may experience stronger and/or faster heart beats. 

  • Electrical signals produced by your heart will then be picked up by the catheters and recorded. This is called cardiac mapping, and it allows the doctor to locate where arrhythmias, if any, originates from.

  • EPS usually lasts 1 to 2 hours.

What happens after EPS?

  • You will be transferred to a recovery room to rest for 1 to 3 hours.

  • Instructions will be given to keep the arm or leg, used for the test, straight. 

  • Your nurse will check on you to see if there is bleeding or swelling at the puncture site. 

  • Before you leave, home care instructions will be given.

Are there any risks?

  • During EPS you may experience abnormal heart rhythms that could make you dizzy. If this happens, your doctor may give your heart an electric shock to bring back a regular heartbeat.

  • Blood clots sometimes can form at the tip of the catheter, break off and block a blood vessel. Your doctor may give you medicine to prevent blood clots.

  • Infection, bleeding and bruising at the site where the catheter is inserted (groin, arm or neck). Your doctor or nurse will help you avoid these problems.

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