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Electrophysiology Studies

You may not have thought about it much until your doctor told you that you have a problem with your heart rhythm, the speed and pattern of your heartbeat. Whether you've been diagnosed with a heart rhythm problem or have symptoms that suggest one, your do

A Problem with Your Heart Rhythm:

You may not have thought about it much until your doctor told you that you have a problem with your heart rhythm, the speed and pattern of your heartbeat. Whether you've been diagnosed with a heart rhythm problem or have symptoms that suggest one, your doctor is now recommending an Electrophysiology study (EPS) to learn more about your heart.

Symptoms You May Feel:

Symptoms of a heart rhythm problem include the following:

  • Dizziness
  • Weakness
  • Fainting spells
  • Shortness of breath
  • Palpitations (a fluttering, strong, or fast heartbeat)
  • Chest pain or discomfort
A serious heart rhythm problem can stop the heart from pumping blood. This life threatening condition is known as cardiac arrest. (Note: Cardiac arrest is not the same as a heart attack, which is when a blockage prevents blood flow through a part of the heart.)

Electrophysiology Studies Can Help:

Your doctor is recommending an EPS because other tests may not have provided enough information about your heart rhythm problem. During EPS, your heart rhythm is closely monitored, and any changes are studied. EPS can help determine exactly what your rhythm problem is and what can be done to control it. A specially trained doctor (electrophysiologist) performs the EPS. Your doctor can discuss what EPS means for you and answer any questions you have.

Normal Heart Rhythms:

Your heart is a muscle that pumps blood through your body. The heart muscle beats (contracts and relaxes) many times a minute with a speed and pattern known as your heart rhythm. Signals from the heart's electrical system set the heart rhythm. If there's a problem with these signals, your heart may beat too slowly, too quickly, or irregularly. Each of these problems is called an arrhythmia.

Your Heart's Pump:

Your heart muscle contains four chambers that hold blood as it moves through the heart. The two upper chambers (atria) receive blood from the lungs and body. The atria contract to move blood through valves into the two lower chambers (ventricles). Then the larger ventricles contract with more force to move blood out to your lungs and body.

Your Heart's Electrical System:

Your heart's electrical system creates signals that tell the chambers to contract. Electrical signals generated inside the heart tell the atria to contract to move blood to the ventricles, then tell the ventricles to contract to move blood to the lungs and body. Groups of special electrical cells in the right atrium, called nodes, create or send these electrical signals. The signals travel along pathways of special cells. In the ventricles, these pathways are called bundle branches.

Slow Heart Rhythms

Sometimes the heart's electrical signals are not sent, are blocked, or take a detour, leading to a slow heart rhythm (bradycardia). When the heart rhythm is slow, your heart beats too slowly. As a result, blood doesn't move through the heart and to the body the way it should. This may happen all the time or only once in a while.

SA Node Problems:

The SA (sinus) node sets the pace of the heart rhythm. If the SA node doesn't send electrical signals often enough or skips some signals, the atria don't contract when they should, and the heart rhythm is too slow. The signals from the SA node may be too slow (sinus bradycardia), may alternate between being too fast and too slow (sick sinus syndrome), or may occasionally stop (sinus pause).

AV Node or Bundle Branch Problems:

Electrical signals travel from the atria to the ventricles through the AV node. If the signal doesn't leave the AV node or move along the bundle branches, the ventricles don't contract when they should, so the heart rhythm is too slow. Blockage of the signal at the AV node or bundle branches is called heart block.

Fast Heart Rhythms:

Sometimes problems with the heart's electrical signals lead to a fast heart rhythm. Too many signals may make the heart beat very fast (tachycardia). Or signals may be sent so rapidly and irregularly that the heart muscle sometimes quivers and doesn't beat at all (fibrillation). Because the ventricles do most of the work to pump blood, fast rhythms in the ventricles are often more serious than those in the atria.

Supraventricular Tachycardia (SVT): SVF is a series of very fast heart contractions that begin in the upper chambers. SVT may happen because an extra pathway exists in the atria, in the AV node, or between the atria and ventricles. The following are two of the most common SVTs that may require an EPS. AV Node Reentrant Tachycardia (AVNRT): With AVNRT, an extra pathway lies near the AV node. Some electrical signals traveling from the atria through the AV node may enter this extra pathway and circle back into the atria. This makes the atria contract repeatedly, speeding up the heart rate.

Atrial Fibrillation and Atrial Flutter:

With atrial fibrillation or atrial flutter, an electrically charged area other than the SA node causes the atria to beat at a very fast and irregular rate, so the atria beat very quickly and ineffectively.

Ventricular Tachycardia (VT):

With VF, abnormal electrical pathways, or circuits develop in the ventricles, usually in an area of heart muscle that's been damaged by heart attack or disease. Electrical signals enter the abnormal circuit and loop around, each time telling the ventricles to contract. This makes the heart beat very fast. VT can sometimes develop into the most serious arrhythmia, ventricular fibrillation

Ventricular Fibrillation (VF):

With VF, the ventricles contain many abnormal circuits. These are usually due to damaged heart muscle. When signals enter the circuits, the ventricles beat very quickly and out of sync, so the heart muscle can't pump effectively. If the heart gets to the point that it can't pump at all (cardiac arrest), death may occur if emergency treatment isn't given to return the heart rhythm to normal.

Your Evaluation:

As part of your evaluation, your doctor takes your health history, examines you, and orders one or more tests, as needed. These tests help diagnose your arrhythmia and provide important information about your heart rhythm. They also help your doctor determine whether an EPS is necessary.

History and Physical Exam:

Your doctor asks about your medical history. You're also asked about your symptoms, such as when you notice them and what they feel like. Tell your doctor if you have any other medical conditions and if you take any medications. As part of the exam, your doctor will also listen to your heart, and your pulse and blood pressure will be taken.


An electrocardiogram (ECG, also called EKG) records your heart' s electrical activity. During this simple test, electrodes are placed on your chest and shoulders. The electrodes record your heart rhythm and any change in your heart's signals that occurs during the test. A stress ECG records your heart's electrical activity while you exercise, usually on a treadmill.


An echocardiogram takes a video picture of your heart. A special probe held over your chest bounces harmless sound waves off the heart, and the returning signals are converted into a moving image on a video screen. Your doctor may order this test if he or she suspects a problem with your heart muscle or heart valves.

Holter and Event Monitoring:

For Holter monitoring, you wear a portable ECG monitor that records your heart rhythm for 24 hours. You also keep a record of your activities during that time. The heart rhythm and activity records are then compared. An event recorder is similar to a Holter monitor, but the recorder is worn for several days to weeks. When you feel symptoms, you press a button, and the monitor records a minute of your heart rhythm.

Tilt Table Testing:

If you've had fainting spells, tilt table testing may be done to determine how changes in your posture affect your blood pressure and heart rhythm. The test is done while you lie on a bed that can be moved from a horizontal to a near vertical position. During the test, the bed is tilted up and down while your symptoms, heart rhythm, and blood pressure are continuously monitored.

Preparing for Your EPS:

Before your Electrophysiology study begins, you'll receive complete instructions on what to expect and how to prepare for it. Follow these instructions closely, and ask your doctor or nurse if you have any questions. The possible risks of the procedure will also be discussed with you.

Before the Procedure:

To prepare for your EPS:

  • Tell your doctor which medications you take, and ask if you should stop taking them before your procedure.
  • Don't eat or drink anything after midnight the night before the procedure.
  • Have any routine tests that your doctor recommends. These tests may be done a few days before the procedure, or they may be done the day of the procedure. The day of your procedure, the skin on your groin, neck, chest, or arm is washed and shaved. Right before the EPS, you may be given medications by an intravenous (IV) line or in pill form to help you relax or sleep.

Understanding the Risks:

The risks of EPS are low and are outweighed by the benefits of learning more about your arrhythmia. Once you understand the risks, you'll be asked to sign a consent form giving your electrophysiologist permission to perform the procedure.

The risks include:

  • Bleeding
  • Blood clots
  • Perforation of the heart muscle or a blood vessel
  • Stroke or heart attack (very rare)
  • Death (extremely rare)

In the EPS Lab:

In the laboratory, you'll be covered with sterile drapes. If you feel cool, the nurse can bring you a blanket. Only the area of skin where the electrode catheter (a thin, flexible, coated wire) will be inserted is exposed. The electrophysiologist, nurses, and technicians wear sterile gowns, gloves, and possibly masks. It may take about half an hour for the EPS lab team to finish their preparations once you're there. When you're positioned comfortably.

The Electrophysiology Study:

The EPS usually takes from 1 to 4 hours. You may be given medication to relax you, or you may be asleep during the procedure. After the study, you usually remain in the hospital for several hours or overnight. Your doctor will talk to you about your EPS results.

Inserting the Wires:

The area (groin, neck, chest, or arm) where the electrode catheter will be inserted is numbed with local anesthetic so you won't feel pain. A small puncture is then made in the vein. One or more catheters are inserted into veins and moved toward the heart. Their movement is monitored on a video screen. The catheter or catheters are then positioned in the heart You won't feel the catheters moving through your blood vessels or heart.

Recovering from Your EPS:

After the EPS is finished, the catheters are removed and pressure is applied to the insertion site for 10 to 20 minutes. You'll need to remain lying down for 4 to 6 hours to allow the blood vessel to seal. If the catheter was inserted into your groin, you'll be asked not to move your leg to prevent bleeding. A nurse will check your blood pressure and the insertion site or sites frequently. You may go home from the hospital the same day, or you may stay one or more days.

Finding Out Your Results:

Your doctor or electrophysiologist will discuss your EPS results with you. The study, along with other test results, may provide enough information for your doctor to develop a treatment plan. If you need medication for your arrhythmia, you may receive it for one or more days in the hospital and then have another EPS to see how well the medication works for you.

Going Home:

When ifs time to go home from the hospital, have a friend or family member drive you. Most people can return to normal activities in a day or two. It's a good idea to avoid heavy lifting and do only light activities for a few days. You may find a small bruise or lump under your skin at the insertion site.

Treating Your Abnormal Heart Rhythm:

The detailed information provided by your EPS can help your doctor plan the next step in treating your arrhythmia. Depending on your particular rhythm problem, treatment options may include medications, catheter ablation, or placement of a device to help control your heart rhythm. You and your doctor can discuss the best treatment for your arrhythmia.


If medication can help control your arrhythmia, your doctor will choose the type that's best for you. In many cases, the effectiveness of certain medications may have been tested during the EPS. Take your medications exactly as prescribed, and don't stop taking your medications without talking to your doctor.

Catheter Ablation:

Catheter ablation destroys (ablates) an abnormal electrical pathway or group of electrical cells that may be causing an arrhythmia. The procedure is often done during or after an EPS. During the procedure, an ablating electrode catheter is placed in the heart. Radio frequency waves are then sent through the catheter to destroy the abnormal pathway or cells. Here are some things to know about ablation: One procedure is usually successful in treating an arrhythmia.For certain types of arrhythmias, ablating the entire AV node is necessary. In these cases, a permanent pacemaker must then be implanted to keep the heart beating at the right pace. Rarely, arrhythmia medications are still necessary after ablation.

Pacemaker for a Slow Heart Rhythm:

A pacemaker helps treat a slow heart rhythm. It is a small, lightweight electronic device that's placed permanently inside your body. A pacemaker keeps track of your heartbeat and, when necessary, generates electrical signals similar to the heart's natural signals. These signals keep your heart beating at the right speed. Lifelong, regular checkups help make sure that your pacemaker continues to run smoothly.

lCD for a Fast Heart Rhythm:

If you have ventricular tachycardia or ventricular fibrillation that's sometimes dangerously fast, an implantable cardioverter defibrillator (ICD) may help. An ICD is a small electronic device placed permanently inside your body. Like a pacemaker, the ICD continuously monitors your heart rhythm. If it senses your heart beating too fast, the ICD can pace the heart to slow down the heart rhythm. If necessary, the ICD can also send out one or more electric shocks to return the heart to its normal rhythm. Lifelong monitoring is necessary to be sure that your ICD continues working correctly and to check for any further changes in your heart rhythm.

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