During the Q-T interval, what physiological event is primarily occurring?

The Q-T interval on an electrocardiogram (ECG) represents the time from the start of ventricular depolarization to the end of ventricular repolarization. During this interval, the ventricles are actively contracting (systole) as indicated by the depolarization phase, followed by repolarization.

The correct answer is that during the Q-T interval, the ventricles are depolarizing and then repolarizing. This is a crucial phase in the cardiac cycle as it encompasses the events that allow the ventricles to contract and then prepare for the next cycle by returning to their resting state.

Understanding the dynamics of the Q-T interval is fundamental for cardiac sonographers because abnormalities in this interval can indicate issues such as long QT syndrome, which can lead to arrhythmias. Being familiar with this timeframe allows a better assessment of cardiac health and function.