Torsades de Pointes

Overview

Torsades de Pointes translates to “twisting of the points”. It is a polymorphic ventricular tachycardia. It is polymorphic because the QRS amplitude varies and the QRS complexes look like they are twisting around the baseline.

Torsades de pointes is associated with a prolonged QT interval and may degenerate into sustained ventricular tachycardia or ventricular fibrillation. Torsades de pointes is a life-threatening arrhythmia that may present as cardiac arrest in people with structurally intact hearts.

Figure 1: An ECG showing torsades de pointes

Epidemiology

• More common in white races
• More common in females
• If it occurs at an earlier age, it is usually due to congenital long QT syndrome
• In later years, it is usually due to acquired long QT syndrome

Risk Factors

• Congenital QT syndromes (described in Long QT Syndrome)
• Acquired QT syndromes (described in Long QT Syndrome):
  • Myocardial infarction
  • Drugs
  • Electrolyte imbalances
  • CNS lesions e.g. subarachnoid haemorrhages

Presentation

Patients may be asymptomatic or have recurrent episodes of symptoms which are usually triggered by stress, fear, or physical exertion. Some recurring features may be:

• Palpitations
• Dizziness
• Syncope:
  • Preceded by: palpitations, shortness of breath, and dyspnoea
  • During: pallor and cyanosis
  • After: recovery period brief and there is flushing
• Sudden cardiac death
• Features of a congenital disorder e.g. sensorineural hearing loss in Jervell and Lange-Nielsen syndrome

Investigations

All patients

• ECG:
  • Shows polymorphic ventricular tachycardia consistent with Torsades de pointes
  • May show QT prolongation
• Urea and electrolytes (U&ES):
  • Particularly potassium, calcium, and magnesium which can contribute to long QT syndrome which is associated with torsades de pointes.
• Cardiac troponins:
  • If acute coronary syndrome is suspected

Management

• 1^st line: IV magnesium sulfate
  • Also withdraw offending drugs and correct electrolyte abnormalities
• Management of long QT syndrome
• In recurrent torsades de pointes, temporary or permanent pacing may be indicated

Complications

• Ventricular tachycardia
• Ventricular fibrillation
• Cardiac arrest

Prognosis

• Some patients may spontaneously revert spontaneously
• Some patients may present with sudden cardiac arrest in an otherwise normal heart
• Acquired long QT syndrome has an excellent prognosis once the precipitating factor has been removed.