What does the T wave represent in an ECG?

The T wave on an electrocardiogram (ECG) represents ventricular repolarization. During this phase, the ventricles, which have just contracted to pump blood out of the heart, are returning to their resting state. This repolarization occurs after the depolarization represented by the QRS complex, which indicates ventricular contraction.

Understanding the significance of the T wave is essential in diagnosing and distinguishing various arrhythmias and cardiac conditions. For instance, abnormalities in the T wave can indicate issues such as electrolyte imbalances, ischemia, or other myocardial concerns. Therefore, recognizing that the T wave is linked to the recovery phase of the ventricles is crucial for interpreting an ECG accurately.

In contrast, the other options refer to different events in the cardiac cycle. Atrial depolarization occurs during the P wave, ventricular depolarization is evident in the QRS complex, and atrial repolarization happens concurrently with the QRS complex but is not represented distinctly on the ECG since it is generally obscured by the greater amplitude of the QRS. This delineation of concepts supports the understanding of the cardiac cycle as illustrated on an ECG.