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Electrophysiological Studies

An electrophysiology (EP) study — also called invasive cardiac electrophysiology — is a series of tests that examine the heart’s electrical activity.

The heart’s electrical system produces signals (impulses) that control the timing of the heartbeats. During an EP study, heart doctors (cardiologists) can create a very detailed map of how these signals move between each heartbeat.

An EP study can help determine the cause of irregular heart rhythms (arrhythmias). Sometimes it’s done to predict the risk of sudden cardiac death.

An EP study is performed in a hospital by cardiologists with special training in heart rhythm disorders (electrophysiologists).

An EP study gives a health care provider a very detailed look at how electrical signals move through the heart. Your health care provider may recommend an EP study if:

  • You have an irregular heart rhythm (arrhythmia). If you’ve been diagnosed with an irregular or fast heartbeat — such as supraventricular tachycardia (SVT) or any other type of tachycardia — your health care provider may recommend an EP study to determine the best treatment.
  • You fainted. If you had a sudden loss of consciousness (fainting, or syncope), an EP study can help understand the cause.
  • You’re at risk of sudden cardiac death. If you have certain heart conditions, an EP study can help determine your risk of sudden cardiac death.
  • You need cardiac ablation. Cardiac ablation uses heat or cold energy to correct heart rhythm problems. An EP study is always done before cardiac ablation to pinpoint the area of the irregular heart rhythm. If you’re having heart surgery, you may have cardiac ablation and an EP study on the same day.

As with many tests and procedures, an EP study has risks. Some can be serious. Possible EP study risks include:

  • Bleeding or infection
  • Bleeding around the heart caused by damage (perforation) to the heart tissue
  • Damage to the heart valves or blood vessels
  • Damage to the heart’s electrical system, which could require a pacemaker to correct
  • Blood clots in the legs or lungs
  • Heart attack
  • Stroke
  • Death (rarely)

Talk to your health care provider about the benefits and risks of an EP study to understand if this procedure is right for you.

Do not eat or drink anything after midnight on the day of an EP study. If you take any medications, ask your health care provider if you should continue taking them before your test.

Your care provider will let you know if you need to follow any other special instructions before or after your EP study.


An EP study is done in the hospital. An IV line is inserted in the hand or arm. Monitors (electrodes) are placed on the chest to check the heartbeat during the test.

Before the procedure starts, you’ll typically receive a sedative through the IV to relax you. Sometimes general anesthesia is used, which means you’ll be put in a sleep-like state.


During an EP study, long, thin tubes (catheters) are placed in three or more heart areas. A care provider shaves any hair from the site where these catheters will be inserted, usually in the groin, and then numbs the area.

The heart doctor inserts plastic tubes similar to large IVs (sheaths) into a blood vessel. The catheters are guided through the sheaths up to the heart, often using moving X-ray images as a guide. Sensors on the tips of the catheters send electrical signals to the heart and record the heart’s electrical activity.

Several different tests can be done during an EP study. Which tests you have will depend on your specific condition and your overall health. During an EP study, a heart doctor can:

  • Take a baseline measurement of the heart’s electrical activity. Sensors at the tip of the catheters record the heart’s initial electrical activity at different locations. This test is called an intracardiac electrogram. It reveals how electrical signals are moving through the heart.
  • Send signals that cause the heart to beat faster or slower. Electrical signals are sent through the catheters to different areas of the heart to speed up or slow down the heartbeat. Doing so helps your health care provider learn if you have extra electrical signals causing an arrhythmia, and where those signals are coming from.
  • Give medicines to see how they affect the heartbeat. Certain medications may be delivered through the catheter directly into the heart to block or slow electrical activity in a certain area. The heart’s reaction to the medication provides more clues about your condition.
  • Map the heart. Also called cardiac mapping, this is the process of determining the best location to apply cardiac ablation to treat an irregular heartbeat.
  • Perform cardiac ablation. If a health care provider determines that cardiac ablation is appropriate, the ablation may be done during the EP study. Cardiac ablation involves using special catheters to apply heat or cold energy to areas of the heart. The energy creates scar tissue that blocks irregular electrical signals to restore a typical heart rhythm.

An EP study doesn’t hurt, but you may feel uncomfortable as your heartbeat speeds up or slows down. Tell your care providers if you feel any pain.

An EP study can take one to four hours. Your test may last longer if you also have cardiac ablation.


Following your EP study, you’ll be moved to a recovery area to rest quietly for four to six hours. Your care providers will monitor your heartbeat and blood pressure to check for complications.

Most people go home the same day. Plan to have someone else drive you home after your test and to relax for the rest of the day. You may feel some soreness for a few days where the catheters were inserted.

Your health care provider will share the results of your EP study with you after the test, usually at a follow-up appointment. The care provider may also make recommendations for treatment based on the results.

Published by The Mayo Clinic