Which EKG findings are classic in hypokalemia?

Which EKG findings are classic in hypokalemia?

• A. Peaked T waves, widened QRS
• B. Delta waves
• C. U waves, T-wave flattening or inversion, ST-segment depression
• D. ST elevations

Answer: (C)

Low potassium levels slow and disrupt ventricular repolarization, which shows up on the ECG as a set of characteristic changes: prominent U waves following the T wave, T waves that are flattened or inverted, and ST-segment depression. The U wave is an extra deflection that becomes noticeable when potassium is low; the T wave loses amplitude or inverts because repolarization is uneven across the ventricles; and the ST segment tends to stay depressed. Altogether, these signs reflect delayed and dispersed repolarization, and they can come with QT interval prolongation as repolarization is extended. By contrast, the other patterns point to different problems: peaked T waves with a wide QRS suggest hyperkalemia; delta waves indicate pre-excitation syndromes like WPW; ST elevations are typical of acute myocardial injury or pericarditis.

Low potassium levels slow and disrupt ventricular repolarization, which shows up on the ECG as a set of characteristic changes: prominent U waves following the T wave, T waves that are flattened or inverted, and ST-segment depression. The U wave is an extra deflection that becomes noticeable when potassium is low; the T wave loses amplitude or inverts because repolarization is uneven across the ventricles; and the ST segment tends to stay depressed. Altogether, these signs reflect delayed and dispersed repolarization, and they can come with QT interval prolongation as repolarization is extended. By contrast, the other patterns point to different problems: peaked T waves with a wide QRS suggest hyperkalemia; delta waves indicate pre-excitation syndromes like WPW; ST elevations are typical of acute myocardial injury or pericarditis.