The QT interval is an indication of which phase of the cardiac cycle?

The QT interval is an indication of which phase of the cardiac cycle?

• A. Atrial systole
• B. Ventricular systole
• C. Atrial diastole
• D. Ventricular diastole

Answer: (B)

The QT interval is specifically used to measure the duration of electrical activity in the ventricles during the cardiac cycle. It represents the time from the beginning of the Q wave to the end of the T wave on an electrocardiogram (EKG). This interval signifies the complete process of ventricular depolarization and repolarization, which occurs during ventricular systole and the subsequent phase of relaxation. Understanding that the QT interval reflects this timing is crucial, as it gives insights into the heart's electrical stability and can indicate various cardiac conditions. Hence, associating the QT interval with ventricular systole is grounded in its function and timing within the cardiac cycle.