During which phase does the T wave occur in the cardiac cycle?

The T wave occurs during the relaxation phase of the ventricles in the cardiac cycle. This phase is known as ventricular repolarization, when the ventricular muscle cells are transitioning from an excited state back to their resting state after the vigorous contraction indicated by the previous QRS complex on the electrocardiogram (ECG).

During this time, the ventricles are no longer contracting and are instead filling with blood as they prepare for the next heartbeat. The T wave visually represents this electrical activity as the myocardium resets and prepares for the subsequent cycle of depolarization and contraction.

Understanding the timing of the T wave is crucial, especially in recognizing abnormalities in a patient’s cardiac function through ECG interpretation, which can indicate issues such as ischemia or electrolyte imbalances.