Torsade de Pointes

Report:

Sinus tachycardia 104/min

First degree AV block (PR 0.25”)

Borderline QTc prolongation (0.38”)

VEBs, multiform

Dimorphic couplet (beginning of bottom strip)

Run of multiform ventricular tachycardia, probably torsade de pointes

Comment:

The basis for calling this instance of VT torsade de pointes is its characteristic shape, called by Marriott ‘the swinging pattern’, as well as the slightly prolonged repolarisation (perhaps longer in other leads) and the setting of severe neurologic disease and malnutrition. There was even a relative (VEB-induced) bradycardia when it happened. The swinging pattern is diagnostic of ventricular ectopic origin. It is perhaps unfortunate that the French name has won the day, probably through its greater snob value183!

Sudden death often follows the beat terminating a post-ectopic pause, especially one induced by a dimorphic couplet184. This is related to the delay and dispersal of ventricular repolarisation, a malignant determinant of arrhythmogenesis. However, not all the instances of torsades de pointes end in sudden death (VF), as this case illustrates: 50% recover spontaneously.

Further episodes were abolished by magnesium infusion. Magnesium is a rather weak anti-arrhythmic agent, but wonderful (and safe) when it works!