Significance of a wide QRS complex?

• A. It confirms atrial fibrillation
• B. It may indicate ventricular tachycardia
• C. It rules out tachycardia
• D. It indicates normal conduction

Answer: (B)

A wide QRS complex signals that ventricular activation is not happening through the normal His-Purkinje system, often reflecting ventricular origin or a conduction delay within the ventricles. In a rhythm that is fast, a broad QRS strongly suggests ventricular tachycardia rather than a supraventricular rhythm with normal conduction. This is because VT produces abnormal, slower, or disrupted ventricular depolarization, leading to the wider complexes.

Atrial fibrillation typically shows irregular rhythm but the QRS width is usually normal unless there’s another conduction issue, sowide QRS alone is not a marker for AF. It also doesn’t rule out tachycardia; in fact, a wide QRS tachycardia is a form of tachycardia. And it does not indicate normal conduction, since normal conduction would produce a narrow QRS.

Thus, a wide QRS complex may indicate ventricular tachycardia.