What is an electrophysiology (EP) study?
In a healthy heart, electricity flows throughout the heart in a regular pattern from the right atrium. This electrical system enables heart muscle contractions. If a problem occurs along the electrical pathway, an arrhythmia (or, abnormal heart rhythm) can occur. By accurately diagnosing the cause of an arrhythmia, it becomes possible to select the best form of treatment.
During an electrophysiology (EP) study, a specialty-trained cardiac physician may provoke arrhythmia events and collect data about the flow of electricity during these events. EP studies can help doctors to locate the specific areas of heart tissue that are causing the abnormal electrical impulses that lead to arrhythmias. This detailed information about the electrical flow provides valuable diagnostic and treatment information.
Why perform an EP study?
An EP study provides the kind of information that is key to diagnosing and treating arrhythmias. EP studies are most often recommended for patients whose symptoms are indicative of heart rhythm disorders, or for people who may be at risk for sudden cardiac death (SCD). Although it is more invasive than an electrocardiogram (ECG) or echocardiogram (and involves provoking arrhythmias) the test produces data that makes it possible to:
- Diagnose the source of arrhythmia symptoms
- Predict the risk of a future cardiac event (including SCD)
- Assess the need for an implantable device (pacemaker or a defibrillator) or treatment procedure (catheter ablation)
The study is performed in the Electrophysiology Lab (a controlled, clinical environment typically located within a hospital). Local anesthesia and conscious sedation are used to help keep the patient as comfortable as possible. The procedure involves inserting a catheter—a narrow flexible tube with tiny electrodes at the tip, used to record electrical signals and heart pace from special locations in the heart—into a blood vessel, often through a site in the groin or neck, and winding the catheter wire up into the heart. Once the catheter reaches the heart, the electrodes gather data and a variety of electrical measurements are made. This data pinpoints the location of the faulty electrical site. Special maneuvers are done (including pacing from special locations) to try to increase the abnormal heart rhythm in order to study its origin and precise location within the heart. Given the range of expertise and resources close at-hand, the test is very safe and complications are rare.
Once the damaged site (or sites) is confirmed, the doctor may administer medications or electrical impulses to determine their ability to halt the arrhythmia and restore normal heart rhythm.
Based on the data gathered during the EP study, as well as prior data from the clinic visit and electrocardiograms, the doctor may be able to cure the arrhythmia by performing catheter ablation, or may determine the need for a defibrillator (ICD) or a pacemaker.
Throughout the procedure, the patient is sedated but remains awake and still. Patients rarely report experiencing any pain, but sometimes describe feeling some discomfort. Some remain awake and able to watch the procedure on monitors and occasionally ask questions, while others fall sleep. The procedure takes approximately two hours. The patient typically needs to remain still (i.e. in a stationary position) for four to six hours following the surgery, to ensure that the entry point incision begins to heal properly.