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Parts of the heart that make a heartbeat.

Allina Health locations

Experts at these hospitals perform electrophysiology studies:

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Electrophysiology study (EPS)

An electrophysiology study (EPS) is a detailed study of the heart's electrical system and is done to investigate an abnormal heart rhythm (arrhythmia).

The heart's electrical system

The heart has four chambers. Two upper chambers (atria) pump blood to the two lower chambers (ventricles). In order for the heart to pump, it requires an electrical impulse to start a heartbeat.

Each heartbeat originates from the sinoatrial (SA) node — the heart's natural pacemaker — which is located in the upper right atrium.

This impulse travels through the atria, signaling them to contract. The impulse is received by the atrioventricle (AV) node. The AV node acts as a relay center to delay the impulse before sending it from the atria to the ventricles.

The impulse then spreads throughout the muscle of the ventricles, stimulating them to contract.

Normally, impulses are generated from the sinus node at a rate of 60 to 100 beats per minute (bpm). That is called a normal sinus rhythm. Sometimes the heart will beat slower than 60 bpm (called bradycardia) or faster than 100 bpm (called tachycardia).

Tachycardias that start in the upper chambers of the heart are called supraventricular tachycardia. Heartbeats that are too slow or too fast may cause fainting, fatigue, palpitations (fluttering in the chest), shortness of breath, chest pain or pressure.

Before the study

  • Talk with your regular doctor about your medicine needs. Be sure to ask your doctor about your medicines if you:
    • have bleeding problems or if you take blood thinning medicines (such as warfarin)
    • have diabetes (You may need to stop taking or adjust your regular dose of medicine for this test. Be sure to find out what dose(s) to take and when you can return to your usual medicine schedule.)
  • Do not have any food or water after midnight the night before the study.
  • The morning of the study, take the medicines your doctor has told you to take with a sip of water.
  • An intravenous (IV) line will be started to give fluids and medicines during your study. One or more blood tests, and EKG may be taken before the study.
  • Your skin will be shaved and scrubbed at sites including the groin, neck, upper chest and back. Many monitoring patches will be placed on those shaved sites.
  • After your questions have been answered, you will be asked to sign a consent form.
  • You will be taken to the Electrophysiology Lab on a transport cart.
  • Your family members will wait in the waiting area.

During the study

  • After being positioned on the table in the Electrophysiology Lab, you will be connected to many monitors. You will also be gently secured to the table with soft restraints. These are needed because you will likely fall asleep during the study and may wake up disoriented.
  • The skin over the catheter sites will be prepped again. A sterile drape is placed over these sites.
  • You will be given a medicine to make you feel drowsy. The electrophysiologist will numb the skin over the catheter insertion sites. If you have any discomfort, tell the nurse.
  • Sheaths will be placed through the skin and into veins in your groin and/or neck. The catheters are placed through the sheaths and guided to your heart using X-ray. You won't feel the catheters advanced into your heart. A small catheter may be placed into the groin artery and will be used to monitor your blood pressure.
  • The electrophysiologist reviews data and talks with you about the best treatment options for managing your abnormal heart rhythm. These options may include:
    • catheter ablation: This uses a special catheter to deliver high-frequency energy to destroy a tiny portion of the problem heart tissue from the area of arrhythmia.
    • a pacemaker: This permanent therapy may be required if your heart has a problem conducting impulses from the upper to lower chambers.
    • an implantable cardioverter defibrillator: This may be inserted if your heart has a life-threatening arrhythmia. It automatically monitors your heart and delivers a shock to restore the heart to a normal sinus rhythm.
  • At the end of the study the catheters and sheaths will be removed. To prevent bleeding, pressure will be applied to the sites for about 10 to 30 minutes.
  • You will be brought back to your room or prepare to leave the hospital.

After the study

  • You will need to stay in bed for 2 to 5 hours to keep the insertion sites from bleeding.
  • Keep your head flat while in bed.
  • Call your nurse if you feel warmth, pain or swelling at the catheter sites.
  • You will be able to eat and drink. At the end of the rest time you may get up and walk.
  • You may need to stay overnight at the hospital.
  • The IV line will be removed before you go home.

When to call your doctor

Call your doctor if you develop:

  • swelling
  • pain
  • drainage at the catheter sites
  • fever.
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Abnormal heart rhythm

Arrhythmia or dysrhythmia is an irregular heartbeat or rhythm. This can happen when your heart has extra beats, when it beats too fast or too slow.

Learn more about problems with the rhythm of your heart in our Helping Your Heart manual.


Source: Allina Health's Patient Education Department, Helping Your Heart, fourth edition, cvs-ahc-90648; Allina Health's Patient Education Department, Electrophysiology Study (EPS), cvs-ahc-11798
Reviewed by: Allina Health's Patient Education Department
First Published: 10/04/2002
Last Reviewed: 09/21/2011