This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmia 3, Subject name: Medicine
All of the following features given below suggest broad complex ventricular tachycardia except : 
Select and explain. 
A. P waves on ECG, 'walking through the tachycardia', B. QRS duration shoens, C. Capture beats, D. RBBB with small R wave and a large R' wave in V1
B: QRS duration shoens
Answer: B: QRS duration shoens 
Explanation: Ventricular Tachycardia -Independent P waves - lack of coordination between atria - ventricles ECG features of Ventricular tachycardia 1. Premature Ventricular Contractions > 3 consecutive contractions 2. HR > 100 / min 3. Broadening of QRS duration 4. Josephson sign 5. Capture Beats 6. P waves walking through the tachycardia rsR' pattern - RBBB - Aberrancy , not VT ECG - Ventricular tachycardia P waves independent of QRS complexes Fusion and capture beat Josephson sign