Twelve-Lead Electrocardiogram of Torsades de Pointes

Torsades de pointes is a specific type of polymorphic ventricular tachycardia that occurs within the context of an underlying prolonged QTc interval. ¹ It appears in paroxysms and usually terminates spontaneously. ² Duration of the arrhythmia usually ranges from 5 to 15 seconds; the longer episodes may progress to ventricular fibrillation and result in rapid hemodynamic compromise and sudden cardiac death. Due to the brevity of the arrhythmia or, in the event of a longer episode, to the gravely deteriorating condition of the patient, it is very rare to record a 12-lead electrocardiogram (ECG) of torsades de pointes. Therefore, most electrocardiographic appearances of torsades de pointes have been limited to the recordings of rhythm strips.

By chance, an episode of torsades de pointes appeared in this 47-year-old man while a 12-lead ECG was in the process of being recorded. The patient had congenital long-QT syndrome, and the torsades de pointes was precipitated by cocaine abuse. The ECG reveals a prolonged QTc interval in the sinus beats, a short-long-short cycle initiating the torsades de pointes, twisting of QRS complexes around the isoelectric baseline, a rate of 210 beats/min, and the polymorphic nature of the arrhythmia. The mostly similar morphology of the arrhythmias in all leads supports the notion that torsades de pointes results from a generalized disorder of ventricular repolarization, in contrast to monomorphic ventricular tachycardia, in which there is a nidus responsible for the arrhythmia.