Sustained Ventricular Tachycardia:  an episode of ventricular tachycardia with a heart rate of greater than 120 beats per minute, persisting more than 30 seconds.  In Monomorphic VT, all ventricular beats have the same QRS configuration. A right bundle branch block (RBBB) pattern is defined by a mono-, bi-, or triphasic R wave or qR in V1; LBBB pattern is defined by a QS, rS, or qrS in V1.  In Polymorphic VT, ventricular beats may have multiple QRS configurations.