Which segment indicates the completion of ventricular depolarization?

The segment that indicates the completion of ventricular depolarization is the ST segment. During the cardiac cycle, depolarization occurs initially in the atria and then progresses to the ventricles. The QRS complex represents the actual depolarization of the ventricles. However, the ST segment follows the QRS complex and reflects the period when the ventricles are in a plateau phase, where they are fully depolarized before repolarization begins.

This segment is crucial for assessing cardiac ischemia; abnormalities in the ST segment can indicate various cardiac conditions, such as myocardial infarction or other forms of cardiac stress. By understanding the ST segment's position in the cardiac cycle, one can appreciate its role as a marker for the end of ventricular depolarization and the beginning of ventricular repolarization, which is further represented by the T wave.