cardiovascular disorders
Torsades de Pointes Ventricular Tachycardia
Introduction
Torsades de pointes ventricular tachycardia is a specific form of polymorphic ventricular tachycardia in patients with a long QT interval. It is characterized by rapid, irregular QRS complexes, which appear to be twisting around the electrocardiogram (ECG) baseline. This arrhythmia may cease spontaneously or degenerate into ventricular fibrillation. It causes significant hemodynamic compromise and often death. Diagnosis is by ECG. Treatment is with IV magnesium, measures to shorten the QT interval, and direct current defibrillation when ventricular fibrillation is precipitated. The long QT interval responsible for torsades de pointes ventricular tachycardia (TdeP VT) can be acquired, congenital or a combination. QT-interval prolongation predisposes to early after-depolarizations and spatial dispersion of ventricular refractoriness, which can lead to arrhythmias. (For discussion of congenital causes, see Long QT Interval Syndromes , and see also 