What does the presence of a U wave on an ECG suggest?

The presence of a U wave on an electrocardiogram (ECG) is commonly associated with electrolyte imbalances, particularly hypokalemia. U waves can appear following the T wave and are thought to represent repolarization of the Purkinje fibers or the endocardial regions of the heart. When potassium levels in the blood are low, as seen in hypokalemia, the heart's electrical activity can be affected, leading to the appearance of U waves.

While U waves may sometimes be observed in healthy individuals, their notable presence or prominence is often a clinical sign that warrants further investigation into potential underlying issues such as electrolyte imbalances. This association highlights the importance of monitoring electrolyte levels in patients, especially those exhibiting dysrhythmias or other cardiac concerns.