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

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

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

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

An EP study gives your doctor a very detailed look at how electrical signals move through your heart. Your doctor may recommend an EP study if:

• You have an abnormal 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 doctor may do 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, your doctor may recommend an EP study to better understand 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 abnormal 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 your heart valves or blood vessels
• Damage to your heart's electrical system, which could require a pacemaker to correct
• Blood clots in your legs or lungs
• Heart attack
• Stroke
• Death (rarely)

Talk to your doctor 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 your test. If you take any medications, ask your doctor if you should continue taking them before your test.

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

Before

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

Before the procedure starts, you'll 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

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

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

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

• Take a baseline measurement of your 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 your heart.
• Send signals that cause your heart to beat faster or slower. Your doctor may send electrical signals through the catheters to different areas of the heart to speed up or slow down the heartbeat. Doing so helps your doctor learn if you have extra electrical signals causing an arrhythmia, and where those signals are coming from.
• Give medicines to see how they affect your heartbeat. Certain medications may be delivered through the catheter directly into your heart to block or slow electrical activity in a certain area. Your heart's reaction to the medication gives your doctor 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 your doctor determines that cardiac ablation is appropriate, he or she may continue with that procedure during your EP study. Cardiac ablation involves using special catheters to apply heat or cold energy to areas of your heart. The energy creates scar tissue that blocks abnormal electrical signals to restore a normal heart rhythm.

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

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

After

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

Most people go home the same day. Plan to have someone else drive you home after your test and to take it easy for the rest of the day. It's normal to feel some soreness for a few days where the catheters were inserted.

Your doctor will share the results of your EP study with you after the test, usually at a follow-up appointment. He or she may also make recommendations for treatment based on the results.