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.