Which ECG component corresponds to ventricular depolarization?

Which ECG component corresponds to ventricular depolarization?

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

Answer: (D)

Ventricular depolarization is the rapid electrical activation of the ventricles that triggers their contraction. On the ECG this activity appears as the QRS complex—the sharp, large deflections that follow the P wave. The P wave reflects atrial depolarization, the PR interval represents the time it takes for the impulse to travel from the atria through the AV node to the ventricles, and the T wave shows ventricular repolarization, when the ventricles reset electrically after contracting. The QRS complex stands out because the ventricles have much more muscle mass than the atria, producing a larger, more rapid change in voltage during their activation.

Ventricular depolarization is the rapid electrical activation of the ventricles that triggers their contraction. On the ECG this activity appears as the QRS complex—the sharp, large deflections that follow the P wave. The P wave reflects atrial depolarization, the PR interval represents the time it takes for the impulse to travel from the atria through the AV node to the ventricles, and the T wave shows ventricular repolarization, when the ventricles reset electrically after contracting. The QRS complex stands out because the ventricles have much more muscle mass than the atria, producing a larger, more rapid change in voltage during their activation.