Mechanism of ventricular arrhythmias in the long QT syndrome: on hermeneutics.
Both the congenital and acquired long QT syndrome are due to abnormalities (intrinsic and/or acquired) of the ionic currents underlying repolarization. The prolongation of repolarization acts as a priming step for the generation of early afterdepolarizations. In the long QT syndrome, it also is associated with increased dispersion of repolarization. Focal early afterdepolarization-induced triggered beat(s) can infringe on the underlying substrate of inhomogeneous repolarization to initiate polymorphic reentrant ventricular tachycardia that sometimes has a characteristic twisting of the QRS axis, referred to as torsades de pointes.
El-Sherif
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Department of Medicine, State University of New York, Downstate Medical Center, and New York Harbor VA Healthcare System, Brooklyn 11203, USA. nelsherif@aol.com
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology*; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000209:etiology*; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology*