There are several other tachycardia rhythms that can be seen with both stable and unstable tachycardia. These rhythms include monomorphic ventricular tachycardia and polymorphic ventricular tachycardia both of which are wide-complex tachycardias.
Wide complex tachycardias are defined as a QRS of ≥ 0.12 second. Expert consultation should be considered with these rhythms.
These wide-complex tachycardias are the most common forms of tachycardia that will deteriorate to ventricular fibrillation.
Monomorphic Ventricular Tachycardia
With monomorphic VT all of the QRS waves will be symmetrical. Each ventricular impulse is being generated from the same place in the ventricles thus all of the QRS waves look the same.
Treatment of monomorphic VT is dependent upon whether the patient is stable or unstable. Expert consultation is always advised, and if unstable, the ACLS tachycardia algorithm should be followed.
Polymorphic Ventricular Tachycardia
With polymorphic ventricular tachycardia, the QRS waves will not be symmetrical. This is because each ventricular impulse can be generated from a different location. On the rhythm strip, the QRS might be somewhat taller or wider.
One commonly seen type of polymorphic ventricular tachycardia is torsades de pointes. Torsades and other polymorphic VT are advanced rhythms which require additional expertise and expert consultation is advised.
If polymorphic VT is stable the ACLS tachycardia algorithm should be used to treat the patient. Unstable polymorphic ventricular tachycardia is treated with unsynchronized shocks (defibrillation). Defibrillation is used because synchronization is not possible.
These wide complex tachycardias tend to originate in the ventricles rather than like a normal rhythm which originates in the atria.