What is the significance of the T wave in an ECG?

The T wave in an electrocardiogram (ECG) is significant because it represents ventricular repolarization. This is the phase of the cardiac cycle where the ventricles recover from the depolarization that occurs during the QRS complex, which is responsible for ventricular contraction.

During the T wave, the myocardial cells in the ventricles are returning to their resting state and reestablishing sodium and potassium ion concentrations, which is critical for the heart's ability to be electrically responsive for the next contraction. This repolarization prepares the heart for the next cycle of depolarization, allowing for effective pumping of blood.

Understanding the T wave is essential for interpreting an ECG, as abnormalities in this wave can indicate various cardiac conditions, such as ischemia or electrolyte imbalances, which can affect the heart's rhythm and function.