Ventricular Tachycardia (VT)

Ventricular Tachycardia (VT)

Ventricular tachycardia is defined as three or more consecutive premature ventricular ectopics in a series, at a rate above 100 per minute. As the name implies, the tachycardia focus is in one of the two ventricles. In general, the rates of ventricular tachycardia are lesser than that of supraventricular tachycardia. Still they are more likely to produce hemodynamic compromise and are potentially life threatening arrhythmias which need prompt treatment.

Mechanisms of VT

Reentrant – scar related, bundle branch reentry, fascicular tachycardia

Automatic – acute ischemia, electrolyte imbalance, increased sympathetic tone

Triggered activity – early and delayed afterdepolarization, idiopathic right ventricular outflow tract VT

Sustained ventricular tachycardia

Ventricular tachycardia lasting more than 30 seconds or requiring termination before that due to hemodynamic compromise is termed sustained ventricular tachycardia. Nonsustained ventricular tachycardia is one which lasts less than 30 seconds.

Idiopathic right ventricular outflow tract VT

Mechanism of idiopathic RVOT VT is triggered activity. It responds to beta-blockers and verapamil, but the current therapy of choice is radiofrequency catheter ablation. Usually there is no structural heart disease associated with this VT.

Bundle branch reentrant tachycardia

Circuit is confined to the left and right bundle branches. Most often the tachycardia has an left bundle branch block pattern and rarely a right bundle branch block. Either case, the treatment is ablation of the right bundle. The sinus rhythm ECG can manifest an LBBB pattern.