context: An electrophysiology ( EP) study is a test that records the electrical activity and the electrical pathways of your heart. This test is used to help determine the cause of your heart rhythm disturbance and the best treatment for you. During the EP study, your doctor will safely reproduce your abnormal heart rhythm and then may give you different medications to see which one controls it best or to determine the best procedure or device to treat your heart rhythm. An electrophysiology study is used: To determine the cause of an abnormal heart rhythm To decide the best treatment for an abnormal heart rhythm Ask your doctor what medications you are allowed to take. Your doctor may ask you to stop certain medications one to five days before your EP study. If you have diabetes, ask your doctor how you should adjust your diabetes drugs. Do not eat or drink anything after midnight the evening before the EP study. If you must take medications, take them only with a small sip of water. When you come to the hospital, wear comfortable clothes. You will change into a hospital gown for the procedure. Leave all jewelry or valuables at home. Your doctor will tell you if you can go home or must stay in the hospital after the procedure. If you are able to go home, bring a companion to drive you home. Before an electrophysiology study, you will lie on a bed and the nurse will start an intravenous ( IV) line into your arm or hand. This is so you can receive medications and fluids during the electrophysiology study. You will be given a medication through your IV to relax you and make you drowsy, but it will not put you to sleep. The nurse will connect you to several monitors. The skin at the top of both of your legs will be shaved and cleansed with an antiseptic solution. Sterile drapes are used to cover you, from your neck to your feet. A soft strap will be placed across your waist and arms to prevent your hands from coming in contact with the sterile field. An electrophysiologist (a doctor who specializes in the diagnosis and treatment of abnormal heart rhythms) will numb your skin with medication and then insert several catheters into the veins beneath the skin. Guided by the fluoroscopy machine, the catheters are threaded to your heart. The catheters sense the electrical activity in your heart and are used to evaluate your heart's conduction system. The doctor will use a pacemaker to deliver the electrical impulses through one of the catheters to increase your heart rate. You may feel your heart beating faster or stronger. Your nurses and doctor will want to know about any symptoms you are feeling. If your arrhythmia occurs, your doctor may give you medications through your IV to test their effectiveness in controlling it. If necessary, a small amount of energy may be delivered by the patches on your chest to bring back a normal heart rhythm. Based on the information collected during the study, the doctor may continue with an ablation procedure. The EP study takes about two to four hours to perform. However, it can take longer if additional treatments such as catheter ablation are performed at the same time. The doctor will remove the catheters and apply pressure to the site, to prevent bleeding. You will be on bed rest for about one to two hours. An EP study allows the doctor to decide the best treatment for you. In many cases, EP testing and the therapy following can greatly reduce the likelihood of developing abnormal heart rhythms in the future. If you have any questions, do not hesitate to ask your doctor or nurse.