What to Expect: EP Studies

EP Studies

An electrophysiology (EP) study is a specialized procedure conducted by a highly trained cardiac specialist, the electrophysiologist (also called the “EP” for short). In this procedure, one or more thin, flexible wires, called catheters, are inserted into a blood vessel (usually in the groin) and guided into the heart. Each catheter has one or more electrodes to measure the heart’s electrical signals as they travel from one chamber to another.

EP studies are done to diagnose your specific condition, to help determine the best treatment, and to pinpoint the site where therapy may be useful. Two different reports can be created from this test:

  • An electrogram, which is like an electrocardiogram (ECG) of the inside of the heart. It shows the abnormal signals — where they start and how they move around inside the heart

  • A map of the heart’s electrical activity

In an ECG, sensors are attached to your chest. In an electrogram, the sensors (electrodes) are inside your heart.

The latest technology combines an electrical map of the heart with the patient’s CT or MRI scan. This gives the electrophysiologist a three-dimensional view of the patient’s heart.

If you do not experience any abnormal rhythms during the EP test, the electrophysiologist can stimulate the arrhythmia with the electrodes on the catheter. They are also used to help evaluate the effectiveness of some medications in controlling the abnormal rhythm and to assess the need for a device such as a pacemaker or defibrillator (also known as an implantable cardioverter defibrillator, or ICD).

EP studies have been performed safely for many years; complications are very rare.

Preparing for the EP study

  • Your doctor will tell you ahead of time whether to stop taking any of your medications. Do not modify your medications without consulting your doctor.

  • You will have to sign an Informed Consent form, which details any risks or problems that may occur.

  • Usually, your doctor will tell you not to eat or drink for 6 to 8 hours before the test.

  • The area where the catheter will be inserted will be thoroughly cleaned and shaved. This is usually in the groin, but may be in the neck. You will receive a local anesthetic in that area.

  • You will be given a mild sedative.

During the EP study

A team of people will work together to assist in the procedure and assure your safety. Besides the electrophysiologist (or EP, who is a physician), there will be specially trained healthcare technicians and nurses to assist the EP and to monitor your condition.

EP studies are carried out in a specially equipped lab that resembles an operating room. The same precautions for maintaining a sterile environment will be followed.

The EP lab features a lot of equipment — including a type of x-ray system called fluoroscopy. The EP will watch a screen to follow the catheter as it is advanced through your blood vessel and into your heart.

You will lie flat on the surgical table, covered with surgical drapes, except for the area where the catheter will be inserted. You will have an IV in your arm to deliver medications as needed. You will be given a local anesthetic at the point where the catheter will be inserted. There will be a small amount of bleeding at the site, but it will be controlled and there is no danger to you.

EP studies are usually done with “conscious sedation” — that is, you will be given medication to relax you, but you will not be put under general anesthesia. Your doctor will talk to you ahead of time about the level of anesthesia planned for you.

You will be awake, but you must remain still during the procedure. Some patients fall asleep, while others watch the monitors and ask questions.

The electrophysiologist will move the catheter around to measure electricity at different sites in your heart. He or she may administer medications or electrical impulses to aid in evaluating your heart’s rhythm.

Patients seldom complain of pain, although you may have a somewhat unpleasant sensation in your chest.

The EP study usually takes 1-2 hours. If other procedures are done immediately, your time in the EP lab will be longer — up to 6 hours in some cases.

After the EP study

  • If the results of the EP study lead to the conclusion that catheter ablation is the right treatment option, the procedure is usually done immediately.

  • Whether or not you undergo another procedure, you need to remain still for 4-6 hours afterward. This should help the incision where the catheter was inserted to start healing properly. It is normal to have a small lump (about the size of a walnut) at the site. Contact your doctor right away if you experience bleeding, bruising or pain at the insertion site or if you develop a fever over 100°F.

  • Once you can get up and move around, you may feel stiff from lying still for so long.

  • Some doctors want to keep patients overnight to monitor their heart rhythm — particularly if another procedure was done. If you are discharged from the hospital the same day, you should arrange for someone else to drive you home.

For more information:

Heart Rhythm Society
www.hrspatients.org »

American Heart Association
www.americanheart.org »
From the home page, click on “Diseases and Conditions”, then on “Arrhythmias”.

National Institutes of Health
www.nlm.nih.gov/medlineplus/encyclopedia.html »
Select the entry for EP study.