On an ECG, which feature marks ventricular repolarization?

On an ECG, which feature marks ventricular repolarization?

• A. P wave
• B. QRS complex
• C. T wave
• D. ST segment

Answer: (C)

The main signal here is that the heart’s electric activity on an ECG follows the sequence of depolarization and repolarization. The ventricles depolarize during the QRS complex, then they return to resting electrical state during repolarization, which shows up as the T wave. So the T wave specifically marks ventricular repolarization. The P wave is atrial depolarization, the QRS complex is ventricular depolarization, and the ST segment is the brief interval between depolarization and repolarization (the plateau phase of the ventricular action potential), not the repolarization itself.

The main signal here is that the heart’s electric activity on an ECG follows the sequence of depolarization and repolarization. The ventricles depolarize during the QRS complex, then they return to resting electrical state during repolarization, which shows up as the T wave. So the T wave specifically marks ventricular repolarization. The P wave is atrial depolarization, the QRS complex is ventricular depolarization, and the ST segment is the brief interval between depolarization and repolarization (the plateau phase of the ventricular action potential), not the repolarization itself.