Cardiac electrophysiology is the science of elucidating, diagnosing, and treating the electrical activities of the heart. The term is usually used to describe studies of such phenomena by invasive (intracardiac) catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical stimulation (PES). These studies are performed to assess complex arrhythmias, elucidate symptoms, evaluate abnormal electrocardiograms, assess risk of developing arrhythmias in the future, and design treatment. These procedures increasingly include therapeutic methods (typically radiofrequency ablation) in addition to diagnostic and prognostic procedures. Other therapeutic modalities employed in this field include antiarrhythmic drug therapy and implantation of pacemakers and automatic implantable cardioverter-defibrillators (AICD).
The cardiac electrophysiology study (EPS) typically measures the response of the injured or cardiomyopathic myocardium to PES on specific pharmacological regimens in order to assess the likelihood that the regimen will successfully prevent potentially fatal sustained ventricular tachycardia (VT) or ventricular fibrillation VF (VF) in the future. Sometimes a series of EPS drug trials must be conducted to enable the cardiologist to select the one regimen for long-term treatment that best prevents or slows the development of VT or VF following PES. Such studies may also be conducted in the presence of a newly-implanted or newly-replaced cardiac pacemaker or AICD.
A specialist in cardiac electrophysiology is known as a cardiac electrophysiologist, or (more commonly) simply an electrophysiologist. Cardiac electrophysiology is considered a subspecialty of cardiology in most countries and usually requires two or more years of fellowship training beyond a general cardiology fellowship. In early 2011, the Centers for Medicare and Medicaid Services (CMS) promoted cardiac electrophysiology to its own specialty category in the United States. Cardiac electrophysiologists are trained to perform interventional cardiac electrophysiology studies (EPS) as well as surgical device implantations.
Cardiac electrophysiology is a relatively young subdiscipline of cardiology and internal medicine. It was developed during the mid-1970s jointly by Mark E. Josephson, of the University of Pennsylvania School of Medicine in Philadelphia, Pennsylvania, now of Beth Israel Deaconess Medical Center at Harvard Medical School in Boston, Massachusetts, and Hein J. J. Wellens, of the Academic Hospital in Maastricht, Netherlands.
The Heart Rhythm Society, founded in 1979, promotes education and advocacy for cardiac arrhythmia professionals (including cardiac electrophysiologists) and patients. It is the largest society of its kind.