What condition is indicated by the presence of U waves on an ECG?

The presence of U waves on an electrocardiogram (ECG) is primarily associated with hypokalemia, which is a condition characterized by low levels of potassium in the blood. U waves typically appear after the T wave and are considered a sign of repolarization abnormalities.

In hypokalemia, the reduction in serum potassium levels affects cardiac repolarization and can lead to the development of U waves. Potassium plays a crucial role in cardiac electrical activity, and low levels can contribute to delayed repolarization, particularly in the ventricles. This delayed repolarization manifests as prominent U waves on the ECG, which can be a key diagnostic feature in identifying hypokalemia.

While hyperkalemia can lead to a variety of ECG changes, it is more commonly associated with peaked T waves rather than U waves. Conditions like hypocalcemia and hypercalcemia do not typically produce U waves either, as their effects on the ECG are related to altered QT intervals and T wave morphology, not U wave development. Thus, recognizing U waves as an indicator is essential in the assessment and management of patients with hypokalemia.