Wide QRS tachycardia

Wide QRS tachycardia

Tachycardia with QRS width of 120 ms or more is taken as wide QRS tachycardia. It is better to consider wide QRS tachycardia as ventricular tachycardia until proved otherwise. Supraventricular tachycardia with phasic aberrancy, antidromic tachycardia in accessory pathway and supraventricular tachycardia with pre existing bundle branch block are the other types of wide QRS tachycardias. Pseudo S waves and pseudo R’ waves can occur due to P waves occurring immediately at the end of the QRS in a narrow QRS tachycardia, making it an apparently wide QRS tachycardia.
Idiopathic right ventricular outflow tract ventricular tachycardia has a left bundle branch block pattern with inferior axis while left ventricular fascicular tachycardias have right bundle branch block pattern.