Electrophysiology Study

How It Is Done

Before the test

• You will be taken to a special room, sometimes called a "cath lab" or "EP lab." You will lie on a flat table under a large X-ray machine.
• Several small electrodes will be attached to your legs and arms with a special paste or gel. These are connected to an EKG machine that keeps track of the electrical activity of your heart during the test.
• A device called a pulse oximeter may be clipped to your finger. It measures oxygen levels in your blood and monitors your pulse.
• An intravenous (IV) needle will be inserted into a vein in one of your arms to give you fluids or medicine during the test. You will receive a medicine to help you relax (sedative) through the IV line. You may be awake during the test. But even if you are awake, the sedative may make you so sleepy that you may not remember much afterward.
• The area where the doctor plans to insert a catheter will be shaved and cleaned. Sterile towels will be draped over your body, except for the area over the insertion site.

During the test

• A local anesthetic is injected into your skin at the insertion site. This is usually in your groin or neck. When the area is numb, a doctor called a cardiac electrophysiologist inserts the catheter through your skin and into the vein.
• The doctor slowly pushes the catheter through the vein toward your heart. Usually several catheters are used. The doctor moves the catheters into various places in the heart. An X-ray screen shows the doctor where to move the catheters.
• The catheters have small electrical conductors, called electrodes, on their ends. The doctor can use the electrodes to do what is called "pacing." This means sending electrical currents through the catheters to try to re-create your heart rhythm problem. This can tell the doctor what kind of problem you have and the best way to treat it. The doctor may also use pacing to see how well medicines work to control your problem.
• The electrodes also send information to a computer. The computer uses the information to draw pictures of your heart and its rhythm problems. This is called "mapping," because the pictures serve as maps that show the doctor exactly where the problem areas are.
• The doctor might give you a medicine through the IV that starts the abnormal heart rhythm. You might feel your heart beat fast and strong. You might also feel jittery or very nervous.
• A nurse or other assistant will help you stay comfortable and resist the urge to move around. Be careful not to touch the sheets or reach for your groin area, because you could contaminate the sterile areas and increase the risk of infection.
• Your doctor may let you watch the video monitor so you can see the pictures of your heart.
• The test can take 2 to 6 hours. In rare cases, it can take longer.

After the test

• It's important to prevent bleeding after the catheter is pulled out. For example, if the catheter was in your groin, firm pressure will be applied there for about 10 minutes to stop the bleeding. Then a pressure dressing or compression device will be placed over the area.
• You will be taken to an observation room where nurses and others can watch your heart rate, blood pressure, and temperature for a while and check for signs of bleeding. They also watch the pulse, color, and temperature of the arm or leg in which the catheter was placed.
• If the catheter was put in your groin, you will need to lie still and keep your leg straight for several hours. The nurse may put a weighted bag on your leg to keep it still.
• If the catheter was put in your arm, you may be able to sit up and get out of bed right away. But you will need to keep your arm still for at least 1 hour.
• If you have an EP study only, you will likely go home the same day. If you also have ablation or other treatment, you may stay overnight in the hospital. How long you stay in the hospital depends on the type of ablation you have. You may be able to go back to work and your normal routine in 1 or 2 days.