Torsade de Pointes

This is part of: Ventricular Arrhythmias

Torsade de Pointes (TdP)
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Atrial rate	60-100 bpm
Ventricular rate	150-300 bpm
Regularity	regular
Origin	ventricles
P-wave	AV-dissociation
Effect of adenosine	no rate reduction (sometimes accelerates)
Example ECG: Initiation of Torsade de Pointes (TdP) by a short-long-short sequence
Example ECG2: {{{example2}}}

Torsade de pointes is a ventricular tachycardia associated with a long QT interval 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 for an list of causes. Also, a more rare form of short coupled Torsades de Pointes has been observed.[1]

Treatment[2]

• Withdrawal of any offending drugs and correction of electrolyte abnormalities (potassium repletion up to 4.5 to 5 mmol/liter).
• Acute and long-term cardiac pacing in patients with TdP presenting with heart block and symptomatic bradycardia.[3]
• 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.

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.[4]

Examples

• 

  A twelve lead registration of Torsade de pointes. Reprinted with permission Copyright 2001 Texas Heart Institute [5]

• 

  12-lead ECG of Torsades de Pointes (TdP) in a 56-year-old white female with a potassium of 2.4 mmol/L and a magnesium of 1.6 mg/dL.

References

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External Links

• A long list of drugs that can induce Torsade de Pointes