Torsade de pointes.

Torsade de pointes is a distinct electrocardiographic entity, characterized by a periodic undulation of the ventricular complex (QRS) around an imaginary line, simulating a cardiac ballet. It usually manifests in patients with abnormalities of repolarization, as evidenced on the surface electrocardiogram by a prolonged ventricular recovery (QT) interval and may degenerate into a fatal ventricular fibrillation following use of conventional antiarrhythmic agents. Therapy includes correction of the underlying cause, overdrive pacing, and isoproterenol infusion.