Myocardial action potential and action of antiarrhythmic drugs
- Jonathan C Makielski, MD, FACC
Jonathan C Makielski, MD, FACC
- Professor of Medicine
- University of Wisconsin-Madison
Cardiac excitability refers to the ease with which cardiac cells undergo a series of events characterized by:
●Sequential depolarization and repolarization
●Communication with adjacent cells
●Propagation of the electrical activity in a normal or abnormal manner
The heartbeat arises from organized flow of ionic currents through ion-specific channels in the cell membrane, through the myoplasm and gap junctions that connect cells, and through the extracellular space (figure 1) [1,2]. Abnormal excitability leading to arrhythmia can arise from acquired or inherited abnormalities of these elements. Acquired abnormalities in cardiomyopathy are called electrical remodeling. Inherited abnormalities arise from mutations in genes encoding the subunits and associated proteins of these channels and have been associated with familial arrhythmic syndromes and sudden cardiac death. Examples include the congenital long QT syndrome (sodium and potassium current), the Brugada syndrome (mainly sodium current), and congenital heart block (sodium current). (See "Genetics of congenital and acquired long QT syndrome" and "Brugada syndrome: Epidemiology and pathogenesis" and "Etiology of atrioventricular block", section on 'Familial disease'.)To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
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