Which ECG component represents ventricular depolarization?

Which ECG component represents ventricular depolarization?

• A. P-wave
• B. T-wave
• C. QRS complex
• D. P-R interval

Answer: (C)

Ventricular depolarization is the electrical trigger that makes the ventricles contract. On an ECG this rapid, large-phase activity is shown as the QRS complex. The ventricles have substantial muscle mass, and the impulse travels quickly through the heart’s conduction system, producing a sharp, brief deflection. By contrast, the P-wave represents atrial depolarization, the P-R interval covers atrial depolarization plus the time the impulse spends in the AV node before reaching the ventricles, and the T-wave shows ventricular repolarization. So the QRS complex is the component that best represents ventricular depolarization.

Ventricular depolarization is the electrical trigger that makes the ventricles contract. On an ECG this rapid, large-phase activity is shown as the QRS complex. The ventricles have substantial muscle mass, and the impulse travels quickly through the heart’s conduction system, producing a sharp, brief deflection. By contrast, the P-wave represents atrial depolarization, the P-R interval covers atrial depolarization plus the time the impulse spends in the AV node before reaching the ventricles, and the T-wave shows ventricular repolarization. So the QRS complex is the component that best represents ventricular depolarization.