Which statement best describes the T wave on an ECG?

• A. Represents atrial depolarization
• B. Represents ventricular depolarization
• C. Follows the P wave and is in the opposite direction of the QRS
• D. Represents ventricular repolarization and is usually in the same direction as the QRS

Answer: (D)

The T wave shows the ventricles returning to resting electrical state, i.e., ventricular repolarization. It appears after the QRS complex—the part that reflects ventricular depolarization—and is not the P wave, which is atrial depolarization. In most leads, the T wave has the same overall direction as the QRS complex because both reflect ventricular activity along the same electrical vector. There are exceptions in some leads or under certain conditions where the T wave can be inverted, but the typical description is that it represents ventricular repolarization and is usually in the same direction as the QRS.