Torsade de Pointes

Torsades de pointes (TdP) is a specific form of polymorphic ventricular tachycardia occurring in the context of QT prolongation — it has a characteristic morphology in which the QRS complexes “twist” around the isoelectric line. Treatment includes empiric administration of 2g MgSO4 and consideration of overdrive pacing to at least 100 bpm (either chemical with isoproterenol or electrical via transvenous pacing). Overdrive pacing works because tachycardia is protective against early afterdepolarizations. The QT interval is inversely proportional to the heart rate; therefore, at faster heart rates, the QT interval is shorter and there is less opportunity for “early afterdepolarizations” (term used to describe abnormal depolarization during phase 2 or phase 3 of the cardiac action potential).


Torsades de Pointes.



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