An electrophysiology study (EP study) is a test to evaluate your heart's electrical system and to check for abnormal heart rhythms.

Natural electrical impulses coordinate the contractions of the different parts of your heart. This creates the heartbeat, or heart rhythm, and keeps blood flowing the way it should.

During an EP study, your doctor inserts small, thin wire electrodes into a vein in the groin. (Or neck, in some cases.) Your doctor then threads the wire electrodes through the vein and into the heart. To do this, your doctor uses a special type of live X-ray “movie,” called fluoroscopy. Once in the heart, the electrodes measure the heart's electrical signals. Electrical signals are also sent through the electrodes to stimulate the heart tissue to try to cause abnormal heart rhythms. This is done so it can be evaluated and its cause can be found. It may also be done to see how well a medicine is working.

During the EP study, specialists in heart rhythms or an electrophysiology specialist may also map the spread of the heart's electrical impulses during each beat. This is done to help find the source of an abnormal heartbeat.

Your doctor may advise an EP study for these reasons:

• To evaluate symptoms, such as dizziness, fainting, weakness, or palpitation, to see if they might be caused by a rhythm problem. This may be done when other tests have not been clear and your doctor thinks you may have a heart rhythm problem.
• To get information related to abnormally fast or slow heart rhythms.
• To find the source of a heart rhythm problem so an ablation may be done once the source is identified. Ablation is a procedure that creates scar tissue inside the heart to interrupt the abnormal electrical signals. It can often cure abnormal heart rhythms.
• To see how well medicines given to treat a rhythm problem are working.

There may be other reasons for your doctor to recommend an EP study.

Possible risks of an EP study include:

• Bleeding and bruising at the site where the catheter is put into a vein.
• Damage to the vessel that the catheter is put into.
• Formation of blood clots at the end of the catheter(s) that break off and travel into a blood vessel.
• Rarely, infection of the catheter site.
• Rarely, perforation (a hole) in the heart.
• Rarely, damage to the heart's conduction system.

For some people, having to lie still on the procedure table for the length of the study may be uncomfortable or painful.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor before the test.

• Your doctor will explain the test to you and answer your questions.
• You'll be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if anything isn't clear.
• Tell your doctor if you're sensitive to or are allergic to any medicines, iodine, latex, tape, or anesthetic agents (local and general).
• You'll need to fast (not eat or drink anything) for a certain period before the test. Your doctor will tell you how long to fast, usually overnight.
• If you're pregnant or think you may be, tell your doctor.
• Tell your doctor if you have any body piercing on your chest or abdomen (belly).
• Be sure your doctor knows about all medicines (prescription and over-the-counter), vitamins, herbs, and supplements that you're taking.
• Tell your doctor if you have a history of bleeding disorders or if you're taking any anticoagulant (blood-thinning) medicines, aspirin, or other medicines that affect blood clotting. You may need to stop some of these before the test.
• Your doctor may request a blood test before the test to determine how long it takes your blood to clot. Other blood tests may be done as well.
• A sedative (a medicine to make you relax) is often given before the test. You'll need someone to drive you home afterwards.
• Your doctor may request other specific preparation based on your medical condition.

You may have an EP study on an outpatient basis, or as part of your stay in a hospital. Testing may vary depending on your condition and your doctor's practices.

Generally, an EP study follows this process:

1. You'll be asked to remove any jewelry or other objects that may interfere with the test.
2. You'll remove your clothing and put on a hospital gown.
3. You'll be asked to empty your bladder before the test.
4. The hair may be shaved off at the area of the catheter insertion (often the groin area) if there is a lot of hair there. This will help in healing and reduce the chance of infection after the test.
5. An I.V. (intravenous) line will be started in your hand or arm before the test. This is so medicine and I.V. fluids can be given, if needed.
6. A member of the medical team will connect you to an electrocardiogram (ECG) monitor to record the electrical activity of your heart and monitor your heart during the test. It uses small electrodes that stick to your skin. The team will also watch your vital signs (heart rate, blood pressure, breathing rate, and oxygen level).
7. There may be several monitor screens showing your vital signs and the images of the catheter being moved through your body into your heart.
8. You'll likely be given a sedative in your I.V. before the test to help you relax. However, you will be somewhat awake during the test.
9. A member of the medical team will inject a local anesthetic into the skin at the site where the catheter and wires are to be put into the vein. You may feel some stinging at the site for a few seconds after the local anesthetic is injected.
10. Once the local anesthetic has taken effect, your doctor will insert one or more sheaths, or introducers, into the blood vessel. This is a plastic tube through which the catheter(s) will be put into the blood vessel and advanced into the heart. Catheters are long, thin hollow tubes that provide a path through the blood vessel. They protect the surrounding blood vessels from damage as the equipment is passed through the vessel.
11. One or more catheters will be put into the sheaths and into the blood vessel. The doctor will thread the catheters through the blood vessel into the right side of the heart. Fluoroscopy (a special type of X-ray that is displayed on a TV monitor) is used to help advance the catheters to the heart. Your doctor may let you watch this process on the screen.
12. Once the catheter is in the right place, your doctor will send very small electrical impulses to certain areas within the heart. You may feel your heart beat stronger and faster. You may feel lightheaded or dizzy if a heart rhythm abnormality is started. Medicine may be given or a shock may be delivered to stop the arrhythmia. You may be sedated before a shock is given.
13. The doctor may do an ablation to destroy some abnormal tissue if a certain area of tissue is found to be causing a rhythm problem. Thermal ablation uses heat or cold to destroy the heart tissue that's causing the abnormal rhythm. Pulsed field ablation uses short electrical pulses to target only the problem cells and is mainly used for atrial fibrillation.
14. Sometimes adrenaline type medicines are given to help induce arrhythmia. You may feel your heart beating more rapidly and forcefully. You may feel some anxiety.
15. If you notice any discomfort or pain, such as chest pain, neck or jaw pain, back pain, arm pain, shortness of breath, or breathing difficulty, let the doctor know right away.
16. Once the EP study is done, the catheter will be removed. Closure devices are used to prevent bleeding. These include internal stitches (sutures) or manual compression.
17. The staff will help you slide from the table onto a stretcher so you can be taken to the recovery area. If the catheter was put in the groin, you won't be able to bend your leg for several hours. The knee of the affected leg may be covered with a sheet and the ends will be tucked under the mattress on both sides of the bed to form a type of loose restraint. This will help you remember to keep your leg straight.
18. The results of the study may also help your doctors decide whether more treatment is needed and which treatment would be best. You may need a pacemaker or implantable defibrillator, receive or change medicines, undergo an ablation procedure, or have other treatments.

After the test, you may be taken to the recovery room for observation or returned to your hospital room. You'll stay flat in bed for several hours after the test to allow the insertion site to stop bleeding. A nurse will keep track of your vital signs, the insertion site, and circulation or sensation in the affected leg or arm.

Let your nurse know right away if you feel any chest pain or tightness, or any other pain, as well as any feelings of warmth, bleeding, or pain at the insertion site.

Bed rest may vary from 2 to 6 hours depending on your specific condition.

After the period of bed rest, you may get out of bed. The nurse will help you the first time you get up. They may check your blood pressure while you are lying in bed, sitting, and standing. You should move slowly when getting up from the bed to prevent any dizziness from the long period of bed rest.

You may be given pain medicine for pain or discomfort at the insertion site or from having to lie flat and still for a long period.

You may go back to your usual diet after the test, unless your doctor tells you otherwise.

You may be sent home when you have recovered unless your doctor decides otherwise. You must have another person drive you home if this test was done on an outpatient basis.

Once at home, check the insertion site for bleeding, unusual pain, swelling, and abnormal color or temperature change. A small bruise is normal. Call your doctor right away if you notice a constant or large amount of blood at the site that can't be contained with a small dressing and pressure. Also call right away if you have a hard lump under the skin that does not go away by putting pressure over the area.

It will be important to keep the insertion site clean and dry. Your doctor will give you specific bathing instructions.

You may be advised not to take part in any strenuous activities for a few days after the test. Your doctor will tell you when you can return to work and go back to your normal activities.

Contact your doctor right away if:

• You have a fever with a temperature higher than 100.4°F (38°C) , or as advised by your doctor.
• You're short of breath.
• You have chills.
• You have increased pain, redness, swelling, bruising, or bleeding, or other drainage where the catheter was inserted.
• You have nausea or vomiting.

Call 911, or get immediate medical care if:

• You feel coolness, numbness or tingling, or other changes in the affected leg.
• You have a sudden increase in swelling around the puncture site.
• You have bleeding that can't be quickly stopped with pressure on the area.
• You have chest pain or pressure, difficulty breathing, heavy sweating, dizziness, or fainting.
• You have signs of stroke, such as face drooping, arm weakness, or problems speaking.

Your doctor may give you other instructions after the test, depending on your situation.

Before you agree to the test or procedure, make sure you know:

• The name of the test or procedure.
• The reason you are having the test or procedure.
• What results to expect and what they mean.
• The risks and benefits of the test or procedure.
• What the possible side effects or complications are.
• When and where you are to have the test or procedure.
• Who will do the test or procedure and what that person's qualifications are.
• What would happen if you did not have the test or procedure.
• Any alternative tests or procedures to think about.
• When and how you will get the results.
• Who to call after the test or procedure if you have questions or problems.
• How much you will have to pay for the test or procedure.