Torsades de Pointes


Torsades de pointes, or simply “Torsades”, is a French term that literally means “twisting of the points”. This is a relatively rare variety of ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG). A typical ECG of Torsades demonstrates a rapid, polymorphic ventricular tachycardia with a characteristic twist of the QRS complex around the isoelectric baseline. It is usually 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 simultaneously to 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.

Some of the causes of Torsades are below.

Common causes for Torsades de Pointes include electrolyte imbalances, which may be a result of diarrhea, vomiting, dialysis and dehydration. Alcoholics are also more prone to this dysrhythmia.

Some medicines such as erythromycin or moxifloxacin, taken concomitantly with inhibitors like nitroimidazole, dietary supplements, and various medications like methadone, lithium, tricyclic antidepressants or phenothiazines may also contribute to Torsades de Pointes. Further, it can be an adverse effect of some medicines, such as sotalol, procainamide and quinidine.

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