What happens during an electrophysiology (EP) study?

The electrophysiology (EP) study is done in a room (called the EP lab) that has special equipment and heart-monitoring machines. A trained team of doctors, nurses and technicians are present during the test. You may be awake during the test (unless you are told otherwise). Here’s what will happen in the EP lab:

• The areas where the catheters are to be inserted will be shaved and scrubbed with an antiseptic solution.
• The doctor will numb these areas with a local anesthetic.
• Catheters may be inserted into veins in your arm and groin and positioned in your heart. You may feel some pressure or slight discomfort as the catheters are inserted.
• Using the catheter, the doctors will try to start, and then observe, any abnormal heart rhythm.
• If an abnormal rhythm is found and does not stop by itself, the doctors will try to restore the regular rhythm with medication or by pacing the heart.
• If the medication and pacing are unable to stop a very fast rhythm, it may be necessary to deliver an electrical shock using patches placed on your chest and back prior to the procedure.

You will be asked to lie as quietly as possible during the study because the recording equipment is sensitive to any motion. If you feel pain, nausea, dizziness or palpitations, tell the staff right away. The test will take about 1 to 1-1⁄2 hours.

When it is finished, the catheters will be removed and pressure will be applied to prevent bleeding. A pressure dressing may be applied and kept on for at least six hours. Sometimes other procedures are scheduled after the EP study.

Typically, an EP study takes 1 to 2 hours. A combined procedure (EP and cardiac ablation) may take 3 to 4 hours or longer. You will sleep through the procedure.

The first step in an EP study is inserting one or more catheters.

• Anesthesia: First, medication will be given so you go to sleep and sleep through the procedure.
• Preparation: A nurse will prepare each patch of skin where a catheter will be inserted.
• Monitoring: You will have monitoring devices attached to check your heart rate, breathing, and other information.
• Inserting catheters: Your  doctor will first insert a sheath (a short plastic tube) into a blood vessel. Each catheter will be put into the sheath and threaded through the blood vessel to the heart. Guidance is provided by x-ray imaging techniques.
• Recording the heart’s electrical signals: The healthcare team uses sensors in the catheters to gather information about how electrical signals travel through your heart. It’s like an ECG (echocardiogram, or “heart ultrasound”) measured directly from the heart muscle, rather than from the surface of your chest.
• Pacing the heart: Next, the doctor uses a catheter to stimulate the heart. The goal is to reproduce your heart rhythm problem. This way, doctors can measure the electrical signals while the problem happens. The measurements can show the cause of the problem and help doctors find the tissue that is operating abnormally.
• Evaluating medications: You might be given medications through the IV to see whether they are effective in reducing the problem.
• Removing the catheter(s): Numbing medication will be applied to the catheter sites. Each catheter will be threaded back through the vein and removed. Then the sheath will be removed.
• Sealing the catheter site: A doctor or nurse will apply pressure to the site to prevent bleeding, and a bandage or pressure bandage will be placed on the site.