Cellular basis and mechanism underlying normal and abnormal myocardial repolarization and arrhythmogenesis.
Regional differences in repolarization characteristics of distinct cell types are responsible for the inscription of the J wave and T wave of the electrocardiogram (ECG). Amplification of these electrical heterogeneities contributes to the development of a variety of cardiac arrhythmias. This brief review examines the ionic and cellular basis for these heterogeneities and their role in the Brugada and long-QT syndromes. Both cases involve an accentuation of transmural dispersion of repolarization (TDR). In the case of the Brugada syndrome. TDR is accentuated as a result of a preferential abbreviation of the right ventricular epicardial action potential, whereas in the long-QT syndrome, accentuation of TDR is secondary to a preferential prolongation of the action potential of the M cell.
Antzelevitch
Charles
C
Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, New York 13501, USA. ca@mmrl.edu
D000200:Action Potentials; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D004562:Electrocardiography; D006321:Heart / Q000502:physiology / Q000503:physiopathology; D006801:Humans; D008133:Long QT Syndrome / Q000503:physiopathology*