4th May 2025

Polymorphic VT

Background

Polymorphic VT is defined as an unstable rhythm with a continuously varying QRS complex morphology. A subtype of polymorphic VT is Torsades de Pointes (Twisting of the points) and is often precipitated by prolongation of the QT interval. Torsades de Pointes if left untreated can lead to Ventricular fibrillation.

Image Source: Wikimedia Commons (2011). Torsades converted by AICD ECG Strip Lead, Licensed under a creative commons licence. Available for free at: https://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Torsades_converted_by_AICD_ECG_strip_Lead_II.JPG/640px-Torsades_converted_by_AICD_ECG_strip_Lead_II.JPG (Accessed: 1 May 2025).

Causes of Long QT interval

Congenital

• Jervell-Lange-Nielsen syndrome (deafness)
• Romano-Ward syndrome (no deafness)
• Long QT syndrome

Drugs

• Sotalol, Amiodarone
• SSRIs (Citalopram)
• Tricyclic antidepressants (Amitriptyline)
• Antipsychotics (Haloperidol, Quetiapine, Risperidone)
• Azithromycin
• Ondansetron
• Methadone

Other

• Subarachnoid haemorrhage
• Hypokalaemia
• Hypomagnesaemia
• Hypocalcaemia
• MI
• Myocarditis

Medical management

• Unstable patients (haemodynamic compromise) need urgent shocking as for patients with monomorphic VT
• Pharmacological management is the same as that of monomorphic VT
• Correct underlying cause
• IV Magnesium Sulphate