Podcast 1023: Torsades de pointes

Contributor: Aaron Lessen, MD

Educational Pearls:

Case review of a patient with recurrent episodes of syncope and shortness of breath, during which she is found to have intermittent runs of polymorphic ventricular tachycardia

Torsades de pointes is polymorphic ventricular tachycardia occurring in the setting of a prolonged QT/QTc

Risk of torsades increases substantially when QTc exceeds 500ms

Causes:

Common reversible causes include QT-prolonging medications, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, and structural heart disease

Congenital causes of a prolonged QT interval are primarily inherited genetic mutations affecting cardiac myocyte ion channels leading to delayed ventricular repolarization

Treatment:

Stop any QT-prolonging medications and correct electrolytes

IV magnesium to suppress recurrent torsades

Increasing the heart rate with isoproterenol or temporary pacing can prevent the pauses that trigger recurrent episodes