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Torsade de Pointes: Difference between revisions
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Torsade de pointes is a ventricular tachycardia associated with a [[Conduction#The_QT_time|long QT time]] on the resting ECG. Torsade de pointes is typically initiated by a short-long-short interval. A ventricle extrasystole (first beat: short) is followed by a compensatory pause. The following beat (second beat: long) has a longer QT interval. If the next beat follows shortly thereafter, ther is a good chance that this third beat falls within the QT interval, resulting in the R on T phenomenon and subsequent Torsades de pointes. During Torsades de pointes the ventricles depolarize in a circular fashion resulting in QRS complexes with a continuously turning heart axis around the baseline (hence the name ''Torsade de Pointes''). Read the chapter on the [[Long_QT_syndrome|Long QT Syndrome]] for an list of causes. | Torsade de pointes is a ventricular tachycardia associated with a [[Conduction#The_QT_time|long QT time]] on the resting ECG. Torsade de pointes is typically initiated by a short-long-short interval. A ventricle extrasystole (first beat: short) is followed by a compensatory pause. The following beat (second beat: long) has a longer QT interval. If the next beat follows shortly thereafter, ther is a good chance that this third beat falls within the QT interval, resulting in the R on T phenomenon and subsequent Torsades de pointes. During Torsades de pointes the ventricles depolarize in a circular fashion resulting in QRS complexes with a continuously turning heart axis around the baseline (hence the name ''Torsade de Pointes''). Read the chapter on the [[Long_QT_syndrome|Long QT Syndrome]] for an list of causes. | ||
'''Treatment'''<cite>ACC</cite> | |||
* Withdrawal of any offending drugs and correction of electrolyte abnormalities. | |||
* Acute and long-term cardiac pacing in patients with TdP presenting with heart block and symptomatic bradycardia.<cite>Eldar</cite> | |||
The guidelines suggest that the weight of evidence supports the following (weaker recommendations): | |||
* Intravenous magnesium sulfate for patients with QT prolongation and few episodes of TdP. | |||
* Acute and long-term cardiac pacing for patients who have recurrent, pause-dependent TdP. | |||
* Beta blockers combined with cardiac pacing as acute therapy for patients with TdP and sinus bradycardia. | |||
* Isoproterenol as temporary treatment in patients with recurrent pause-dependent TdP who do not have congenital long QT syndrome. | |||
The guidelines also suggest that the following interventions may be considered, although supporting evidence is less well-established: | |||
* Potassium repletion to 4.5 to 5 mmol/liter. | |||
* For patients with long QT syndrome 3 (LQT3) and TdP, intravenous lidocaine or oral mexiletine. | |||
There has been much debate in the ''Circulation'' journal among French and American scientist whether one should write ''Torsades de Pointes'' or ''Torsade de Pointes''. As for now ''Torsade'' is prefered (unless one sees rotations around more than one axis in one episode), but both forms are used in similar frequency.<cite>Moise</cite> | There has been much debate in the ''Circulation'' journal among French and American scientist whether one should write ''Torsades de Pointes'' or ''Torsade de Pointes''. As for now ''Torsade'' is prefered (unless one sees rotations around more than one axis in one episode), but both forms are used in similar frequency.<cite>Moise</cite> | ||
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#Moise pmid=10500317 | #Moise pmid=10500317 | ||
#Khan pmid=11330748 | #Khan pmid=11330748 | ||
#Eldar pmid=3624666 | |||
#ACC pmid=16949511 | |||
</biblio> | </biblio> | ||
==External Links== | ==External Links== | ||