Cardiac electrophysiology

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EKG complex — Drawing of the EKG, with labels of intervals

Cardiac Electrophysiology (also referred to as clinical cardiac electrophysiology , Arrhythmia Services , or electrophysiology), is a branch of the medical specialty of clinical cardiology and is concerned with the study and treatment of rhythm disorders 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 implantable cardioverter-defibrillators.

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, and in most countries requires two or more years of fellowship training beyond a general cardiology fellowship. Cardiac electrophysiologists are trained to perform interventional cardiac electrophysiology studies (EPS) as well as surgical device implantations.

Cardiologists with expertise in this area are usually referred to as electrophysiologists. Electrophysiologists are trained in the mechanism, function, and performance of the electrical activities of the heart. Electrophysiologists work closely with other cardiologists and cardiac surgeons to assist or guide therapy for heart rhythm disturbances (arrhythmias).They are trained to perform interventional and surgical procedures to treat cardiac arrhythmia. The training required to became an electrophysiologist is long and requires 7 to 8 years after medical school (in the U.S.). Three years of Internal Medicine residency, three years of Clinical Cardiology fellowship, and one to two (in most instances) years of Clinical Cardiac Electrophysiology.

Cardiac electrophysiology is a relatively young subdiscipline of cardiology and internal medicine. It was developed during the mid-1970's 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, The Netherlands.

An electrophysiologic study is a term used to describe a number of invasive (intracardiac) and non-invasive recording of spontaneous electrical activity as well as of cardiac responses to programmed electrical stimulation. These studies are performed to assess arrhythmias, elucidate symptoms, evaluate abnormal electrocardiograms, assess risk of developing arrhythmias in the future, and design treatment.

In addition to diagnostic testing of the electrical properties of the heart, electrophysiologists are trained in therapeutic and surgical methods to treat many of the rhythm disturbances of the heart. Therapeutic modalities employed in this field include antiarrhythmic drug therapy and surgical implantation of pacemakers and implantable cardioverter-defibrillators.

Scope of practice, tests and procedures[]

Diagnostic testing[]

Ambulatory electrocardiographic monitoring - Holter recording and interpretation, loop recording and interpretation;
Tilt table testing;
T-wave alternans testing;
Signal-averaged electrocardiogram (SAECG) interpretation, also referred to as "late potentials" reading;
Electrophysiologic study (EPS) consists in the insertion of pacing and recording electrodes either in the oesophagus (intra-oesophageal EPS) or, through blood vessels, directly into the heart chambers (intra-cardiac EPS) in order to measure electrical properties of the heart and, in the case of intra-cardiac EPS, to electrically stimulate it in the attempt to induce arrhythmias for diagnostic purposes ("programmed electrical stimulation").

Medical treatment[]

Initital administration and monitoring of the effect of drugs for treatment of heart rhythm disorders. Electrophysiologists are often involved when severe or life threatening arrhythmias are being treated, or when multiple drugs must be used to treat an arrhythmia.

Catheter ablation[]

Ablation therapy - Catheter based creation of lesions in the heart (with radiofrequency energy, cryotherapy (destructive freezing), or ultrasound energy) to cure or control arrhythmias (see radiofrequency ablation). Ablation is usually performed during the same procedure as the electrophysiology study which induces and confirms the diagnosis of the arrhythmia for which ablation therapy is sought.

"Non-complex" ablations include ablation for arrhythmias such as: AV nodal reentrant tachycardia, Accessory pathway mediated tachycardia, atrial flutter. These procedures are usually performed using intracardiac catheters (as are used during an electrophysiologic study), fluoroscopy (a real-time X-ray camera), and electrical recordings from the inside of the heart.

"Complex" ablations include ablation for arrhythmias such as multifocal atrial tachycardia, atrial fibrillation, and ventricular tachycardia. In addition to the apparatus used for a "non-complex" ablation, these procedures often make use of sophisticated computer mapping systems to localize the source of the abnormal rhythm and to direct delivery of ablation lesions.

Surgical Procedures: Pacemaker and Defibrillator implantation and follow up[]

Implantation of single and dual chamber pacemakers and defibrillators
Implantation of "biventricular" pacemakers and defibrillators for patients with congestive heart failure
Implantation of loop recorders (implanted ECG recorders for long term monitoring of ECG to allow for diagnosis of an arrhythmia)
Clinical follow up and reprogramming of implanted devices

External links[]

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