Basic mechanisms of reentrant arrhythmias.
The mechanisms responsible for active cardiac arrhythmias are generally divided into two major categories: (1) enhanced or abnormal impulse formation and (2) reentry. Reentry can be subdivided into three subcategories: (1) circus movement, (2) reflection, and (3) Phase 2 reentry. Reentry occurs when a propagating impulse fails to die out after normal activation of the heart and persists to re-excite the heart after expiration of the refractory period. Evidence implicating reentry as a mechanism of cardiac arrhythmias stems back to the turn of the century. Amplification of intrinsic electrical heterogeneities provides the substrate responsible for developing Phase 2 and circus movement reentry, which underlie ventricular tachycardia in the long QT and Brugada syndromes.
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Masonic Medical Research Laboratory, Utica, New York, USA. ca.mmrl.edu
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D004594:Electrophysiology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008955:Models, Cardiovascular