Electrophysiology Study

An electrophysiology (EP) study is a minimally invasive heart test (a test that involves a small skin incision) that evaluates the electrical conduction system of your heart.


An EP study is done if other non-invasive heart tests (tests that do not make skin incisions) have not found the cause of unexplained symptoms such as:

  • Dizziness or fainting.

  • A fast heart beat (tachycardia).

  • A slow heart beat (bradycardia).


  • Your caregiver will explain how an EP study is done. If you have any questions about the EP study, be sure to ask your caregiver.

  • Do not eat or drink before the EP study as instructed by your caregiver.

  • Be sure to urinate before the EP study.

  • Let your caregiver know about any allergies you have. This includes allergies to food, medicine or latex products.

  • Tell your caregiver about all prescription medicine (especially blood thinners), over the counter and herbal medications you take.

  • Let your caregiver know if you have a history of bleeding problems.

  • If you are going home after the EP study, someone will need to drive you home and stay with you for 24 hours. Do not make major decisions for 24 hours after the EP study.


  • An EP study is performed in a cath lab room. This is a room set up to do heart procedures.

  • An intravenous (IV) line will be put in your arm. Medication will be given through the IV to help you relax.

  • Your groin will be shaved and cleansed with an antibacterial cleanser. Sterile drapes will cover you. This will keep the groin area sterile.

  • A medication will be injected into your groin area to numb it. Then, a thin, flexible tube (catheter) with an electrode tip will be inserted into a large vein (femoral vein) in your groin. From there, the catheter is guided to the heart using a special type of X-ray machine (fluoroscopy). Once in the heart, the catheter will help evaluate the electrical activity of your heart.

  • During the EP study:

  • You may feel dizzy or lightheaded.

  • Your heart rate may temporarily increase or you may feel your heart beating hard.

  • Tell your caregiver if you feel dizzy, nauseated, or have chest pain or pressure during the EP study.


  • When the EP study is done, the catheter is removed.

  • Firm pressure is applied to the groin insertion site. This is done to help the insertion site clot.

  • You will need to lie flat for a few hours or as told by your caregiver. You will need to keep your legs straight. Do not bend or cross your legs. This is done so the clot at the insertion does not break loose and start bleeding.

  • If you took blood thinners before the EP study, ask your caregiver when you can start taking them again.


If the cause of your symptom(s) is found during the EP study, your caregiver will discuss treatment options. Some treatment options that may be done to correct your symptoms can include:

  • Ablation. An ablation is a source of energy that destroys a small area of heart tissue that may be causing a fast heart rate (tachycardia).

  • Implantable cardioverter defibrillator(ICD). An ICD can detect a fast or abnormal heart rate. When an abnormal rhythm is detected, the ICD shocks the heart to restore it to a normal heart rhythm.


Complications can occur during an EP study. Possible complications include:

  • A fast heart rate (tachycardia) that does not go away. This may require shocking your heart (cardioversion).

  • Bleeding or bruising from the catheter insertion site.

  • Temporary heart rhythm abnormalities.

  • Temporary changes in blood pressure.

  • Puncture (perforation) of the heart wall. This can cause bleeding between the heart and the sac that surrounds it (cardiac tamponade). This is a life-threatening condition which may require open heart surgery.

  • Possible cardiac arrest or fatal heart arrhythmia.

  • Infection at the groin insertion site.


  • You have bleeding from the groin insertion site.

  • You develop a hard spot at the groin insertion site. This could be a clot (hematoma) at the insertion site.

  • You have a large amount of bruising that expands from the groin insertion site.

  • You develop chest pain or have "heaviness" in your chest.

  • You develop nausea or vomiting.

  • You become dizzy or feel faint.