Electrophysiology study
A cardiac electrophysiology study (EP test or EP study) is a minimally invasive procedure using catheters introduced through a vein or artery to record electrical activity from within the heart. This electrical activity is recorded when the heart is in a normal rhythm (sinus rhythm) to assess the conduction system of the heart and to look for additional electrical connections (accessory pathways), and during any abnormal heart rhythms that can be induced. EP studies are used to investigate the cause, location of origin, and best treatment for various abnormal heart rhythms, and are often followed by a catheter ablation during the same procedure. It is important for patients not to eat or drink for up to 12 hours before the procedure. This is to prevent vomiting, which can result in aspiration, and also cause severe bleeding from the insertion site of the catheter. Failure to follow this simple preparation may result in dangerous consequences. In general, small amounts of water can be consumed up to 2 hours before the exam. Patients should try to schedule the exam at a time when they will be having symptoms and will not need to drive for 2 to 3 days. An EP study is typically performed in an EP lab or cath lab. These are specially equipped operating rooms that usually contain an X-ray machine capable of acquiring live X-ray video images (a fluoroscope), equipment to record electrical signals from the heart, a stimulator to electrically excite the heart and control the heart rate, and ablation equipment to destroy abnormal tissue. A 3D navigation system that tracks and records the catheter position and associated electrical signals may also be used. The procedure may be performed awake under local anaesthetic, or under general anaesthetic. Monitoring equipment is attached including an automated blood pressure cuff and a pulse oximeter to measure the oxygen saturation of the blood. A peripheral venous cannula is generally inserted to allow medication to be given such as sedatives, anesthesia, or drugs.
