An electrophysiology (EP) study is a series of tests that check the heart's electrical activity. It's also called invasive cardiac electrophysiology.

The heart's electrical system gives off signals that control the timing of the heartbeats. During an EP study, heart doctors called cardiologists can make a detailed map of how these signals move between each heartbeat.

An EP study can help find the cause of irregular heartbeats, called arrhythmias. Sometimes doctors also use it to predict the risk of sudden cardiac death, which happens when the heart suddenly stops working.

An EP study takes place in a hospital or clinic. Doctors with extra training in heart rhythm conditions, called electrophysiologists, give you this series of tests.

An EP study gives your healthcare team a very detailed look at how electrical signals move through your heart. You may need an EP study if:

• You have an irregular heartbeat. If you have an irregular or fast heartbeat, an EP study can help figure out the best treatment. For example, an EP study can be helpful if you have any type of tachycardia. That's a heart rate over 100 beats a minute. A common type of this condition is called supraventricular tachycardia (SVT).
• You fainted. If you suddenly passed out, an EP study can help find the cause.
• You're at risk of sudden cardiac death. If you have certain heart conditions, an EP study can help figure out your risk of sudden cardiac death.
• You need a treatment called cardiac ablation. Cardiac ablation uses heat or cold energy to correct irregular heartbeats. Healthcare professionals do an EP study before cardiac ablation to find the exact area of the irregular heartbeat. If you're having heart surgery, you may have cardiac ablation and an EP study on the same day.

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

• Bleeding or infection.
• Bleeding around the heart caused by damage 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 with your healthcare professional about the benefits and risks of an EP study to learn if it's right for you.

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

A member of your care team tells you if you need to follow any other special instructions before or after your EP study.

Before

You get an EP study in a hospital or clinic. A healthcare professional places an IV line in a vein in your hand or arm. Sticky patches with sensors, called electrodes, go on your chest. They check your heartbeat during the test.

A member of your care team shaves any hair from the area where a small cut, called an incision, will be made. Usually this is in the groin area. Thin tubes called catheters go through the cut into the body for the test.

Before the test starts, you typically get medicine called a sedative to relax you. Or you may get a mix of medicines, called general anesthetics, to put you in a sleeplike state.

During

During an EP study, thin, flexible tubes called catheters are placed in three or more areas of the heart.

The heart doctor puts the catheters into a blood vessel. The doctor guides the catheters 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.

A heart doctor can do different tests during an EP study. The tests you have depend on your specific condition and overall health. During an EP study, a heart doctor can:

• Measure the electrical signals at different areas in the heart. Sensors at the tips of the catheters record the heart's electrical activity at various places. This test is called an intracardiac electrogram. It shows how electrical signals are moving through the heart.
• Send signals that cause the heart to beat faster or slower. The doctor sends electrical signals through the catheters to different areas of the heart. These signals speed up or slow down the heartbeat. This can show if extra electrical signals are causing an arrhythmia and where those signals start.
• Give medicines to see how they affect the heartbeat. Some medicines may go through the catheter directly into the heart. These medicines can block or slow electrical activity in a certain area. The heart's reaction to the medicine gives more clues about your condition.
• Map the heart. This also is called cardiac mapping. It's the process of figuring out the best location to do cardiac ablation to treat an irregular heartbeat.
• Do cardiac ablation. If a doctor decides that you need cardiac ablation, the doctor may do the treatment during the EP study. Cardiac ablation uses special catheters to apply heat or cold energy to certain areas of the heart. This creates scar tissue that blocks irregular electrical signals and restores a typical heartbeat.

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

An EP study can take 1 to 4 hours. Your test may last longer if you also have cardiac ablation.

After

After your EP study, your healthcare team usually moves you to a recovery area to rest quietly for 4 to 6 hours. Your care team tracks 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 plan to relax for the rest of the day. You may feel some soreness for a few days where the catheters were placed.

Call a member of your healthcare team if you run a fever or if the area where the catheter was placed:

• Feels numb, tingles or changes color.
• Has bruising that appears to become worse.
• Becomes swollen or leaks fluids.

Call 911 or your local emergency number if you have:

• Shortness of breath.
• Pain or tightness in your chest.
• Facial drooping, weakness in your arm or trouble speaking.
• Swelling around the catheter site that suddenly becomes worse.
• Bleeding that doesn't stop when you apply firm pressure.

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