What indicates that the heart is in a state of rest?

The T wave represents the repolarization of the ventricles, indicating that the heart is in a state of rest after contraction. During this phase, the heart muscle is recovering and preparing for the next heartbeat. The T wave follows the QRS complex, which represents the depolarization of the ventricles and correlates with the contraction of the heart.

Understanding the function of the T wave is crucial for interpreting an EKG, as it provides insight into the heart's recovery phase. A normal T wave indicates that the heart is effectively resting and resetting its electrical state. Abnormalities in the T wave can signify potential issues in heart function or electrolyte imbalances.

The other components mentioned, such as the P wave and QRS complex, indicate different aspects of the cardiac cycle. The P wave represents atrial depolarization, the QRS complex indicates ventricular depolarization and contraction, while the S-T segment reflects the time between ventricular depolarization and repolarization. Each of these plays a role in the overall cardiac function but does not directly signify the resting state of the heart in the same way that the T wave does.