Torsade de pointes (TdP) is a distinctive and potentially life-threatening form of ventricular tachycardia in which the QRS complexes appear to twist around the baseline of the ECG, with varying amplitude and axis. The name comes from the French for ‘twisting of the points’, describing its characteristic ECG appearance.
TdP occurs in the context of a prolonged QT interval (the period on the ECG representing ventricular depolarisation and repolarisation). A long QT creates a window of electrical vulnerability during which an early ectopic beat can trigger the arrhythmia. The QT prolongation may be congenital (as in Long QT Syndrome) or acquired (caused by medications, electrolyte abnormalities, or structural heart disease).
Common acquired causes of QT prolongation that can precipitate TdP include certain antibiotics (such as azithromycin and clarithromycin), antipsychotic medications, antiarrhythmics (including amiodarone), and electrolyte disturbances (particularly low potassium and low magnesium). This is why checking the QT interval and monitoring electrolytes is important when prescribing these medications in cardiac patients.
TdP is typically not sustained and terminates spontaneously, but it frequently recurs and can degenerate into ventricular fibrillation and cardiac arrest. Acute management involves intravenous magnesium sulphate, correction of electrolyte imbalances, and withdrawal of causative medications. For congenital long QT syndrome, beta-blockers and ICD implantation are the mainstays of long-term prevention.
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