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Polymorphic VT

critical
Lead II
25 mm/s10 mm/mV
Heart rate
72bpm
RR
833ms
QT
378ms
Type

Polymorphic VT

A rapid ventricular tachycardia with beat-to-beat variation in QRS morphology, amplitude, and axis. Unlike Torsades de Pointes, polymorphic VT occurs with a normal baseline QT interval and is most commonly caused by acute myocardial ischemia.

Mechanism

A rapid ventricular tachycardia with beat-to-beat variation in QRS morphology, amplitude, and axis. Unlike Torsades de Pointes, polymorphic VT occurs with a normal baseline QT interval and is most commonly caused by acute myocardial ischemia.

Findings· 4
  • Rapid, irregular wide-complex tachycardia with continuously changing QRS morphology.
  • No consistent repeating pattern.
  • Rate typically 200–300 bpm.
  • Distinguished from Torsades by normal baseline QT.
Clinical Impact

Life-threatening. Most commonly indicates acute myocardial ischemia. Treatment: immediate defibrillation if pulseless, IV amiodarone, emergent coronary angiography. Unlike Torsades, magnesium is not the primary treatment.

Differential· 2
Torsades de Pointes

Both polymorphic VT. Torsades has prolonged baseline QT and characteristic spindle shape.

Ventricular Fibrillation

Very rapid polymorphic VT can resemble VFib. VFib is completely disorganized with no identifiable QRS.