Which interval represents total ventricular activity?

The QT interval represents total ventricular activity due to its measurement encompassing both ventricular depolarization and repolarization. Specifically, the QT interval starts at the beginning of the Q wave (the first negative deflection after the P wave) and ends at the end of the T wave (the final positive deflection that represents ventricular repolarization).

By capturing the period from depolarization (when the ventricles contract and pump blood) to repolarization (when the ventricles are reset electrically and ready for the next contraction), the QT interval provides crucial information about how well the ventricles are functioning and their recovery time.

In summary, the QT interval is vital for assessing ventricular health and rhythm, as it reflects the complete cycle of electrical activity in the ventricles, making it the correct choice for representing total ventricular activity.