What does the Q-T interval represent in an ECG?

The Q-T interval in an electrocardiogram (ECG) specifically represents the time from the beginning of ventricular depolarization to the end of ventricular repolarization. This interval encompasses several critical phases of the cardiac cycle, including the initiation of the electrical impulse that causes the ventricles to contract (depolarization) as well as the recovery phase when the ventricles reset (repolarization).

Understanding the Q-T interval is essential because it can provide insights into the health of the heart's electrical system. Anomalies in the Q-T interval can be indicative of various cardiac issues, such as arrhythmias or the potential effects of certain medications on cardiac function. Monitoring the Q-T interval is a key part of assessing a patient's cardiac health.

In contrast to this, the other options describe different phases of the cardiac cycle or intervals that do not accurately define the Q-T interval.