Which rhythm typically presents with wide QRS complexes and a duration of 0.12 seconds or longer?

• A. Atrial fibrillation
• B. Ventricular tachycardia
• C. Normal sinus rhythm
• D. Sinus tachycardia

Answer: (B)

Wide QRS complexes (0.12 seconds or longer) indicate that ventricular depolarization is starting in the ventricles themselves rather than being conducted through the normal His-Purkinje system. Ventricular tachycardia is a rhythm that originates in the ventricles, so it most commonly shows a wide QRS because the ventricles are activated abnormally and asynchronously. The other rhythms—atrial fibrillation, normal sinus rhythm, and sinus tachycardia—originate above the ventricles and typically produce narrow QRS complexes unless there’s an underlying conduction block, which is not their defining feature. So the presentation of wide QRS ≥0.12 seconds is characteristic of ventricular tachycardia.