Cardiac Medicine Certification (CMC) Practice Exam

The area from the end of the S wave to the end of the T wave on an ECG represents:

1. Atrial depolarization

2. Ventricular depolarization

3. Ventricular repolarization

4. Resting potential

The correct answer is: Ventricular repolarization

The area from the end of the S wave to the end of the T wave on an ECG represents ventricular repolarization. This interval is defined as the ST segment and the T wave, which together signify the recovery phase of the ventricles after they have contracted. During this phase, the ventricles are in the process of returning to their resting state after depolarization and contraction. The S wave marks the end of ventricular depolarization, while the T wave signifies the completion of the repolarization process. Understanding this phase is critical, as it can provide insights into the heart's electrical activity and how well it is functioning. Additionally, the other areas mentioned in the choices are distinct and do not overlap with the interval representing ventricular repolarization. Atrial depolarization occurs prior to the onset of the QRS complex, while ventricular depolarization itself is represented by the entire QRS complex. Resting potential refers to the state of the cardiac cells when they are not conducting electrical impulses, which is not specifically represented by any particular segment on the ECG. Thus, recognizing that the time from the end of the S wave to the end of the T wave specifically indicates the ventricular repolarization phase is key.