What ECG pattern is typical of hyperkalemia?

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Multiple Choice

What ECG pattern is typical of hyperkalemia?

Hyperkalemia alters cardiac conduction by increasing extracellular potassium, which slows conduction and changes repolarization. On the ECG this shows up as tall, peaked T waves first, followed by PR prolongation as AV nodal conduction slows, then diminished or absent P waves, and finally widening of the QRS complex as ventricular conduction becomes markedly slowed. In severe cases, the QRS and P waves can fuse into a sine-wave pattern, signaling high risk of fatal rhythm disturbances. The pattern described—tall peaked T waves, PR prolongation, diminished P waves, widening QRS with progression to sine wave—is the classic progression of hyperkalemia. The other patterns point to different situations: flattened T waves with prominent U waves occur with hypokalemia; a short QT interval is not typical of hyperkalemia; and delta waves indicate WPW pre-excitation.

Hyperkalemia alters cardiac conduction by increasing extracellular potassium, which slows conduction and changes repolarization. On the ECG this shows up as tall, peaked T waves first, followed by PR prolongation as AV nodal conduction slows, then diminished or absent P waves, and finally widening of the QRS complex as ventricular conduction becomes markedly slowed. In severe cases, the QRS and P waves can fuse into a sine-wave pattern, signaling high risk of fatal rhythm disturbances. The pattern described—tall peaked T waves, PR prolongation, diminished P waves, widening QRS with progression to sine wave—is the classic progression of hyperkalemia.

The other patterns point to different situations: flattened T waves with prominent U waves occur with hypokalemia; a short QT interval is not typical of hyperkalemia; and delta waves indicate WPW pre-excitation.

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