Torsades de Pointes - Presentation

Presentation

The ECG tracing in torsades demonstrates a polymorphic ventricular tachycardia with a characteristic illusion of a twisting of the QRS complex around the isoelectric baseline. It is also associated with a fall in arterial blood pressure, which can produce syncope. Torsades de pointes can degenerate into ventricular fibrillation, which will lead to sudden death in the absence of medical intervention. Torsades de pointes is associated with long QT syndrome, a condition whereby prolonged QT intervals are visible on the ECG. Long QT intervals predispose the patient to an R-on-T phenomenon, where the R wave representing ventricular depolarization occurs during the relative refractory period at the end of repolarization (represented by the latter half of the T-wave). An R-on-T can initiate torsades. Sometimes pathologic T-U waves may be seen in the ECG before the initiation of torsades.

A variant of Torsades de pointes which presents without Long QT syndrome exists, referred to as the "Short-coupled variant of torsade de pointes" in literature and first described in 1994.