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 generat ion of early afterdepolarizations. In the long QT syndrome, it also is asso ciated with increased dispersion of repolarization. Focal early afterdepola rization-induced triggered beat(s) can infringe on the underlying substrate of inhomogeneous repolarization to initiate polymorphic reentrant ventricu lar tachycardia that sometimes has a characteristic twisting of the QRS axi s, referred to as torsades de pointes.