In the event of cardiac arrest, what underlying cause should be suspected if a 12-lead ECG shows flat T waves and prominent U waves?

When interpreting a 12-lead ECG, flat T waves and prominent U waves can indicate specific electrolyte imbalances, particularly hypokalemia. In the context of cardiac arrest, hypokalemia is often associated with decreased potassium levels in the bloodstream. This deficiency can lead to alterations in cardiac repolarization, which is reflected in the ECG findings.

Flat T waves suggest that the heart muscle is not repolarizing effectively, while prominent U waves can indicate that the repolarization process is disrupted, often seen in hypokalemic patients. The presence of these specific ECG changes aligns with a clinical scenario where low potassium levels have a direct impact on heart function, leading to arrhythmias or cardiac arrest.

This understanding reinforces the importance of monitoring electrolyte levels in patients at risk of cardiac issues and provides a pathway for effective treatment, such as potassium supplementation if hypokalemia is confirmed.