Ventricular Tachycardia – Classification
Ventricular tachycardia is a common arrhythmia. The manifestations include mild symptoms of palpitation to sudden death. In next few blog posts, we will try to understand the basics of ventricular tachycardia/fibrillation and we will discuss management of these arrhythmias.
Ventricular arrhythmias are defined as arrhythmias that originate below the bifurcation of His bundle, in the specialized conduction system, the ventricular muscle, or in combination of both tissues.
Ventricular Tachycardia ECG
(Image created by Karthik Sheka, M.D. [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons)
There are different classifications of ventricular arrhythmias, according to their duration, morphology of QRS complexes, and clinical characteristics.
Classification According to Duration
(1) Premature ventricular complexes (PVC): isolated complexes originating from the His-Purkinje system or ventricular myocardium.
(2) VT: 3 or more consecutive QRS complexes at a rate greater than 100 beats per minute.
(3) Nonsustained VT: VT that terminates spontaneously within 30 seconds.
(4) Sustained VT: continuous VT lasting for ≥30 seconds or that requires an intervention for termination (such as cardioversion).
Classification According to Morphology of QRS Complexes
(1) Monomorphic VT: VT that has a similar QRS configuration from beat to beat. Some variability in QRS morphology at initiation is not uncommon.
(2) Multiple monomorphic VT: more than one morphologically distinct monomorphic VT, occurring as different episodes or induced at different times.
(3) Polymorphic VT: VT that has a continuously changing QRS configuration indicating a changing ventricular activation sequence.
(4) Pleomorphic VT: VT that has more than one morphologically distinct QRS complex occurring during the same episode of VT, but the QRS is not continuously changing.
(5) Ventricular flutter: rapid VT that has a sinusoidal QRS configuration that prevents identification of the QRS morphology.
(6) VF: ventricular tachyarrhythmia that has a totally chaotic
Classification According to Clinical Characteristics
(1) Clinical VT: VT that has occurred spontaneously based on analysis of 12-lead ECG QRS morphology and rate.
(2) Hemodynamically unstable VT: VT that causes hemodynamic compromise requiring prompt termination.
(3) Incessant VT: continuous sustained VT that recurs immediately despite repeated spontaneous or therapeutic termination.
(4) Repetitive monomorphic VT: continuously repeating episodes of self-terminating nonsustained VT.
(5) VT storm: 3 or more separate episodes of sustained VT within 24 hours, each requiring termination by an intervention.
(6) Unmappable VT: VT that does not allow interrogation of multiple sites to define the activation sequence or perform entrainment mapping. It may be due to hemodynamic
intolerance that necessitates immediate VT termination, spontaneous, or pacing-induced transition to other morphologies of VT, or repeated termination during mapping.
In the next post, we will discuss clinical features and ECG features.
DR. ANUPAM JENA
CONSULTANT INTERVENTIONAL CARDIOLOGIST & ELECTROPHYSIOLOGIST
KALINGA INSTITUTE OF MEDICAL SCIENCES