Wide QRS tachycardia @ 300 per min – Cardiology MCQ

Wide QRS tachycardia at 300 per minute can occur with:
a) Atrial fibrillation with Wolff–Parkinson–White syndrome (WPW) syndrome
b) Supraventricular tachycardia with aberrancy in the very young
c) Atrial flutter with 1:1 conduction
d) All of the above
Correct answer: d) All of the above
In AF with WPW syndrome, rate is fast due to conduction through accessory pathway with low refractory period as well as through AV nodal pathway.
Polymorphic ventricular tachycardia is another cause of wide QRS tachycardia at 300/min.
Common form of wide QRS tachycardia is monomorphic ventricular tachycardia (VT or V-tach), which has a much lower rate, usually between 150 – 200/min.