What does the T wave represent in an electrocardiogram?

The T wave in an electrocardiogram (ECG) represents ventricular repolarization. During the cardiac cycle, after the ventricles contract and depolarize during the QRS complex, they must return to a resting state—this process is known as repolarization. The T wave indicates the recovery phase of the cardiac action potential for the ventricles, signifying that they are resetting electrically after contraction in preparation for the next heartbeat.

Understanding the distinct roles of each component of the ECG is essential—while depolarization events such as atrial depolarization and ventricular depolarization are represented by the P wave and QRS complex, respectively, the T wave is solely focused on the ventricles transitioning back to a resting state. Thus, recognizing that the T wave corresponds specifically to ventricular repolarization enhances one's comprehension of cardiac physiology and the overall function of the heart as seen through ECG readings.