The treatment of
torsades de pointes is very effective but also very specific. Prompt recognition of
torsades de pointes is imperative, and the clue to its recognition is increased awareness. The QT interval in the
long QT syndrome (LQTS) is not only prolonged but also odd looking. This abnormal QT morphology, which has been well described for the congenital LQTS, is also observable in the acquired LQTS. Moreover, the onset of
ventricular extrasystoles and the appearance of bizarre QT changes (with giant U waves) in the sinus complex that follows each postextrasystolic pause are signs of "impending torsades."
Emergency treatment includes 1) withdrawal of any precipitating agents; 2)
intravenous administration of
magnesium sulfate,
potassium supplements, and
lidocaine; and 3) adequate sedation. For
drug-refractory
torsades de pointes, transvenous ventricular pacing at rapid rates will shorten the QT interval, eliminate the pauses that precipitate torsades, and prevent further bursts of arrhythmias. Acceleration of the basic heart rate with
isoproterenol is also effective in preventing immediate recurrence.
Isoproterenol should only be used, however, when 1)
torsades de pointes is due to an acquired LQTS; 2) the underlying rhythm is slow, and torsades is clearly "pause dependent"; and 3) transvenous pacing cannot be immediately implemented.