Ventricular tachycardia classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Overview
Ventricular tachycardia refers to a rhythm with a heart rate in excess of 100 (and in some definitions 120) beats per minute that arises distal to the bundle of His.
Ventricular tachycardia can be classified under three main categories:
- The morphology of the QRS complexes on the EKG (monomorphic ventricular tachycardia vs polymorphic ventricular tachycardia
- The duration of the episode
- The symptoms associated with the episode
Classification Based Upon Morphology of the QRS Complexes
Monomorphic ventricular tachycardia
Monomorphic ventricular tachycardia is defined as a QRS complex morphology that is identical from beat-to-beat in all leads of the surface electrocardiogram (EKG).
Example
Polymorphic ventricular tachycardia
Polymorphic ventricular tachycardia, is defined as QRS complexes with beat-to-beat variability in morphology. This most commonly appears as a cyclical progressive change in cardiac axis referred to by its French eponym Torsade de pointes (literally twisting of the points).
Example
Classification Based Upon Duration of Episode
Non Sustained Ventricular Tachycardia or Paroxysmal Ventricular Tachycardia
- Rapid succession of three or more ectopic beats
- Self terminates within 30 seconds
Sustained Ventricular Tachycardia
- Lasts more than 30 seconds
Incessant Ventricular Tachycardia
- The ventricular tachycardia is recurrent and the episodes are interrupted by only a few sinus beats
Classification Based Upon Symptoms
A third way to classify ventricular tachycardia is on the basis of its symptoms:
Pulseless VT
Pulseless VT is associated with no effective cardiac output, hence, no effective pulse, and is a cause of cardiac arrest. In this circumstance it is best treated the same way as ventricular fibrillation (VF) and is recognized as one of the shockable rhythms on the cardiac arrest protocol.
Perfusing Rhythm with VT
Some VT is associated with reasonable cardiac output and may even be asymptomatic. The heart usually tolerates this rhythm poorly in the medium to long term, and patients may certainly deteriorate to pulseless VT or to VF.