What does a U wave typically represent in an EKG?

A U wave in an EKG is typically associated with the repolarization of the Purkinje fibers, which are fibers that help conduct impulses throughout the ventricles of the heart. The presence of a U wave, which usually follows the T wave, indicates that there may be a phase of repolarization occurring that is not adequately captured by the T wave alone. This phase can also correlate with states like bradycardia or electrolyte imbalances, but its primary association is with the repolarization of the Purkinje fibers. Understanding the U wave's connection to the conductive pathway of the heart contributes to a broader interpretation of the electrocardiogram and can be crucial in diagnosing certain cardiac conditions.