As a domain expert in cardiology, I can clarify the relationship between repolarization and diastole. Repolarization and diastole are related but distinct phases of the cardiac cycle. Repolarization refers to the process by which the ventricles return to their resting state after depolarization, which is the initial contraction phase of the cardiac cycle. During repolarization, the ventricles are electrically resetting in preparation for the next heartbeat. Diastole, on the other hand, is the phase of the cardiac cycle when the heart is relaxed and filling with blood. It is the period between the end of one heartbeat and the beginning of the next. The ST segment you mentioned is indeed a period of diastole, specifically when the ventricles are in a state of electrical quiescence, which means there is no depolarization or repolarization occurring. This is why a normal ST segment is flat; it represents a time of zero electrical potential. To summarize, while the ST segment occurs during diastole, repolarization is a specific process that happens within the diastolic phase but is not synonymous with the entire diastolic period. read more >>

The ST?segment is a period of diastole between the end of systole to the beginning of repolarization of the ventricles. When the ST?segment is normal it is a time when no depolarization or repolarization is occurring, and is thus a time of zero potential (flat line at zero).read more >>