Ventricular Tachycardia

This is part of: Ventricular Arrhythmias

Ventricular tachycardia is defined as a sequence of three or more ventricular beats. The frequency must by higher than 100 bpm, mostly it is 110-250 bpm. Ventricular tachycardias often origin around old scar tissue in the heart, e.g. after myocardial infarction. Also electrolyte disturbances and ischemia can cause ventricular tachycardias. The cardiac output is often strongly reduced during VT resulting in hypotension and loss of conciousness. VT is a medical emergency as it can deteriorate into Ventricular fibrillation and thus mechanical cardiac arrest.

Ventricular Tachycardia (VT or V-tach)
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Atrial rate	60-100 bpm
Ventricular rate	110-250 bpm
Regularity	regular
Origin	ventricles
P-wave	AV-dissociation
Effect of adenosine	no rate reduction (can accelerate)
Example ECG: An example of a polymorphic ventricular tachycardia
Example ECG2: Ventricular tachycardia on a 12 lead recording Ventricular tachycardia of 140 bpm with a left bundle branch block and a left axis.

Ventricular tachycardia can be catechorized as follows:

Non-sustained VT

Non-sustained VT is defined three or more ventricular beats with a maximal duration of 30 seconds.

Sustained VT

Sustained VT is defined as a VT of more than 30 seconds duration (or less if treated by electrocardioversion within 30 seconds).

Monomorphic VT

All ventricular beats have the same configuration.

Polymorphic VT

The ventricular beats have a changing configuration. The RR interval is 180-600 ms (comparable to a heart rate of 100-333 bpm).