What ECG change is a hallmark sign of hypokalemia?

The presence of a U wave is indeed a hallmark sign of hypokalemia on an ECG. Under normal circumstances, U waves are often not visible, but when there is a deficiency of potassium, they become more prominent. This occurs due to the effects of low potassium levels on myocardial repolarization. As the heart muscle repolarizes more slowly, it may result in the appearance of U waves following the T wave. Recognizing this specific change is crucial for nurses and healthcare providers when assessing a patient with potential electrolyte imbalances, as timely intervention can prevent complications associated with hypokalemia.

Other changes commonly associated with hypokalemia, such as a flattened T wave or ST segment changes, may also be observed, but the U wave is particularly distinctive and clinically relevant for diagnosis. This specific representation highlights how electrolyte imbalances, like hypokalemia, can manifest through observable and measurable changes in cardiac conduction, aiding in prompt recognition and treatment.