What phase of the cardiac cycle does the T wave indicate?

The T wave on an electrocardiogram (ECG or EKG) represents the phase of ventricular relaxation, also known as ventricular repolarization. During this phase, the ventricles, which have just finished contracting to pump blood out of the heart, are recovering and returning to their resting state. The electrical activity that corresponds to the T wave reflects the repolarization of the ventricular muscle cells as they prepare for the next cycle of contraction.

Understanding the cardiac cycle is fundamental in EKG interpretation. After depolarization, which is represented by the QRS complex when the ventricles contract, the heart muscle needs to reset its electrical state before the next heartbeat can occur. The T wave captures this important phase of relaxation, thus signifying that the ventricles are in the process of recovering. This is crucial for the heart's proper functioning, ensuring that the heart chambers are ready for the next filling and contraction sequence.

In context, other phases such as atrial contraction, nodal delay, and atrial repolarization do not correlate with the T wave. Atrial contraction is depicted by the P wave, nodal delay relates to the PR interval, and atrial repolarization is typically not visually significant on the EKG as it