What does the T wave in an ECG indicate?

What does the T wave in an ECG indicate?

• A. Electrical changes associated with ventricular repolarization.
• B. Electrical changes associated with atrial depolarization
• C. Electrical changes associated with AV node depolarization
• D. Electrical changes associated with atrial repolarization

Answer: (A)

The main concept is that the T wave represents ventricular repolarization. After the ventricles depolarize and contract (the QRS complex), they need to reset their electrical state as they relax. This recovery is ventricular repolarization, and it shows up as the T wave on the ECG. The shape and direction of the T wave reflect how the ventricles recover electrically, influenced by the sequence of repolarization across the ventricular wall. Other clues help place it in context: the P wave corresponds to atrial depolarization, so it is not the T wave. The AV node’s activity is not seen as a separate wave; conduction through the AV node is reflected in intervals like the PR interval rather than a distinct deflection. Atrial repolarization does occur, but it happens during the QRS complex and is usually masked by the larger ventricular depolarization, so it does not appear as its own wave.

The main concept is that the T wave represents ventricular repolarization. After the ventricles depolarize and contract (the QRS complex), they need to reset their electrical state as they relax. This recovery is ventricular repolarization, and it shows up as the T wave on the ECG. The shape and direction of the T wave reflect how the ventricles recover electrically, influenced by the sequence of repolarization across the ventricular wall.

Other clues help place it in context: the P wave corresponds to atrial depolarization, so it is not the T wave. The AV node’s activity is not seen as a separate wave; conduction through the AV node is reflected in intervals like the PR interval rather than a distinct deflection. Atrial repolarization does occur, but it happens during the QRS complex and is usually masked by the larger ventricular depolarization, so it does not appear as its own wave.