Polymorphic refers to the fact that the shape and size of each QRS complex varies from the preceding one.

Polymorphic VT in clinical practice is uncommon and rarely sustained. When polymorphic VT is encountered in the acute setting it is frequently the result of an acute cardiac insult and it rapidly deteriorates into ventricular fibrillation [4].

Torsades de pointes is a type of polymorphic VT see in patients with a congenital or acquired prolonged QT interval.

As with other forms of polymorphic VT, Torsades is not usually sustained but it will recur if the underlying cause is not corrected.