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A common category of heart problems is arrhythmias – abnormal heart rhythms. These problems can deprive vital organs such as the lungs and brain of blood, preventing them from functioning properly – possibly even causing them to shut down.

According to the American Heart Association, electrophysiology (EP) studies test the electrical activity of the heart to determine the cause of an arrhythmia, as well as the appropriate treatment.

Types of Arrhythmias

What happens during an EP Study?

An EP study takes place in a specially equipped room called an electrophysiology laboratory, EP lab, catheterization laboratory or cath lab.

A nurse will put an intravenous line (IV) in your arm and administer a sedative that will help you relax, yet stay awake to follow instructions. Your nurse will clean and shave the part of your body where the doctor will be working, usually in the groin but possibly in the arm or neck. Then you’ll receive a local anesthetic to numb the area.

Your doctor will puncture your skin and enter a blood vessel with a needle. The doctor will gently guide several specialized EP catheters into your blood vessel through a sheath (tube) and advance them to your heart through an artery or vein. A video screen will show the position of the catheters.

Your doctor will send small electric pulses through the catheters to make your heart beat at different speeds. You may feel your heart beat stronger or faster.

Special catheters will record electrical signals produced by your heart. This “cardiac mapping” process allows the doctor to determine where arrhythmias are coming from. Your doctor will remove the catheters and the IV line. Your nurse will put pressure on the puncture site to stop any bleeding. EP studies usually last for one to four hours.

If the type and location of the arrhythmia is identified, your doctor may perform cardiac ablation or insert a pacemaker or implantable cardioverter defibrillator (ICD) during or immediately after the EP study.


Your nurse and doctor will watch for several developments and correct them immediately:

  • You may have abnormal heart rhythms that make you dizzy. If this happens, your doctor may give your heart an electric shock to restore a regular heartbeat.
  • Blood clots sometimes can form at the tip of the catheter, break off and block a blood vessel. In this case, your doctor can give you medicine to prevent blood clots.
  • Your doctor or nurse will help you avoid infection, bleeding and bruising where the catheter was inserted.


Immediately following EP study, you’ll be moved to a recovery room where you should rest quietly for one to three hours. After the sedative wears off, your doctor will talk to you about your test results.

After you get home, follow the instructions your nurse or doctor gave you, including taking any new prescriptions. You’ll probably be able to start eating food and taking your medicines within four to six hours of the test. Also, you’ll probably be able to resume usual daily activities the day after the test, although you shouldn’t drive for at least 24 hours. The puncture site may be sore for several days and a small bruise there is normal.

Treatment for arrhythmias

Most of the time, your doctors have you make an appointment to discuss the test results and recommend treatment: medicine, a pacemaker, an ICD, cardiac ablation or surgery.

Our cardiovascular services

Centegra Health offers a wide range of cardiovascular care resources, including sophisticated testing that can determine the cause of heart arrhythmias. If you and your primary care physician think you might need specialty care, call us at 877-CENTEGRA for more information.