Arnsdorf, Morton F. Department of Medicine-Cardiology, University of Chicago, Chicago, Illinois.
Last reviewed:January 2019
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- Cellular electrophysiology
- Excitation-contraction coupling
- Clinical cardiac electrophysiology
- Related Primary Literature
- Additional Reading
The science of the electrical activity of the heart. Cardiac electrophysiology is the branch of cardiology concerned with the mechanism, spread, and interpretation of the electric currents that arise within heart muscle tissue and initiate each heart muscle contraction (Fig. 1). In particular, the heartbeat results from the development and organized control of cardiac excitability (the ability of a cardiac cell to respond to a stimulus by depolarizing and firing an action potential), including ionic current flow across the cardiac membrane, within and between cells, and throughout the body, which in turn allows the orderly contraction of heart muscle and the efficient pumping of blood. Alterations in these determinants of normal cardiac excitability may lead to abnormalities in the rhythm of the heart (arrhythmias or dysrhythmias) and in the propagation of electrical impulses throughout the heart (conduction defects). Cellular electrophysiologic events lead to the establishment of extracellular potentials on the surface of the body. Electrocardiographic, vectorcardiographic, and other recording systems are used to determine the orientation and magnitude of the extracellular potentials. In addition, the normal heart produces characteristic sequences of extracellular potentials that may be altered by disease. See also: Biophysics; Cardiovascular system; Heart (vertebrate); Heart disorders; Muscle
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