Cardiac electrophysiology

Cardiac electrophysiology
Drawing of the EKG, with labels of intervals

WikiDoc Resources for Cardiac electrophysiology
Articles
Most recent articles on Cardiac electrophysiology Most cited articles on Cardiac electrophysiology Review articles on Cardiac electrophysiology Articles on Cardiac electrophysiology in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Cardiac electrophysiology Images of Cardiac electrophysiology Photos of Cardiac electrophysiology Podcasts & MP3s on Cardiac electrophysiology Videos on Cardiac electrophysiology
Evidence Based Medicine
Cochrane Collaboration on Cardiac electrophysiology Bandolier on Cardiac electrophysiology TRIP on Cardiac electrophysiology
Clinical Trials
Ongoing Trials on Cardiac electrophysiology at Clinical Trials.gov Trial results on Cardiac electrophysiology Clinical Trials on Cardiac electrophysiology at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Cardiac electrophysiology NICE Guidance on Cardiac electrophysiology NHS PRODIGY Guidance FDA on Cardiac electrophysiology CDC on Cardiac electrophysiology
Books
Books on Cardiac electrophysiology
News
Cardiac electrophysiology in the news Be alerted to news on Cardiac electrophysiology News trends on Cardiac electrophysiology
Commentary
Blogs on Cardiac electrophysiology
Definitions
Definitions of Cardiac electrophysiology
Patient Resources / Community
Patient resources on Cardiac electrophysiology Discussion groups on Cardiac electrophysiology Patient Handouts on Cardiac electrophysiology Directions to Hospitals Treating Cardiac electrophysiology Risk calculators and risk factors for Cardiac electrophysiology
Healthcare Provider Resources
Symptoms of Cardiac electrophysiology Causes & Risk Factors for Cardiac electrophysiology Diagnostic studies for Cardiac electrophysiology Treatment of Cardiac electrophysiology
Continuing Medical Education (CME)
CME Programs on Cardiac electrophysiology
International
Cardiac electrophysiology en Espanol Cardiac electrophysiology en Francais
Business
Cardiac electrophysiology in the Marketplace Patents on Cardiac electrophysiology
Experimental / Informatics
List of terms related to Cardiac electrophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Cardiac electrophysiology (also referred to as clinical cardiac electrophysiology , Arrhythmia Services , or electrophysiology) is the science of the mechanisms, functions, and performance of the electrical activities of specific regions of the heart.

The Cardiac Conduction System

• Proper cardiac function heavily depends on the ability of the cardiomyocytes to receive and propagate an electrical impulse allowing the heart to contract.
• These impulses, known as ''action potentials'', originate and travel through the cardiac conduction system.
• A time-ordered propagation of the electrical impulse through the myocardium allows efficient contraction of all four chambers of the heart, starting with the atria pumping the blood toward the ventricles, followed by the ventricles which contribute to the pulmonary and systemic circulation.

The Components of the Cardiac Conduction System:

• The sinus (sinoatrial) node
• The internodal tracts
• The atrioventricular (AV) node
• The His/AV bundle
• The right and left bundle branches,
• The Purkinje fibers.

The Direction of Propagation of the Action Potential:

• The initial cardiac impulse, produced by pacemaker cells, originates in the sinoatrial (SA) node at the intersection of the right atrium and the superior vena cava.
• This action potential is the trigger of every cardiac cycle, initiating the atrial then ventricular contractions; it is henceforth responsible for the rhythmic beating of the heart.
• This action potential then propagates as a wave of depolarization through the internodal tracts initiating atrial contraction and then converging at the AV node.
  • The convergence occurs because, in a normal heart, the AV node is the only electrical connection between the atria and the ventricles.
  • The conduction of this potential is delayed at the AV node mainly due to the slower depolarization in these cells.
  • This delay is represented as the PR interval of the ECG.
• The electrical impulse then moves to the ventricles by means of the AV or His bundle located in the superior portion of the interventricular septum.
• It then continues moving apically and propagating through both [[]]ventricles via the right and left bundle branches, and the Purkinje fibers.

Electrophysiology Studies and Therapeutic Modalities

Overview

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. 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.

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. They are trained to perform interventional cardiac EP procedures as well as surgical device implantations.

Diagnostic testing

• Ambulatory electrocardiographic monitoring - Holter recording and interpretation, loop recording and interpretation;
• Tilt table 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

Scope of practice, tests and procedures:

See also

• Clinical cardiac electrophysiology
• Electrical conduction system of the heart
• Electrocardiogram (EKG)
• Electrophysiologic study
• Cardiology
• Cardiac arrhythmia

External links

• Cardiac Electrophysiology Society
• Heart Rhythm Society
• International Winter Arrhythmia School

Template:WikiDoc Sources