Ventricular tachycardia should be described by type (monomorphic or polymorphic), duration (sustained or non-sustained) and heart rate — i.e. monomorphic VT non-sustained at a heart rate of 220 ...

Sustained ventricular tachycardia is usually defined as VT lasing for more than 30 seconds. VT can be monomorphic (most common) or polymorphic (a.k.a. Torsades de Pointes).