What ECG finding is characteristic of hyperkalemia, and how does it progress?

• A. Peaked T waves progressing to wide QRS complexes and eventually sine wave pattern
• B. ST-segment elevation
• C. Prolonged QT with U waves
• D. Osborn waves

Answer: (A)

Hyperkalemia alters how heart cells conduct electricity, so the ECG changes occur in a characteristic sequence. First you’ll see tall, peaked T waves due to accelerated repolarization. As potassium levels rise further, the PR interval lengthens and the P waves flatten or disappear because atrial conduction slows. Next, the QRS complex widens as ventricular conduction slows. In severe hyperkalemia, the QRS widens enough to merge with the T wave, producing a sine-wave pattern that signals a high risk of lethal arrhythmias.

That progression—peaked T waves advancing to wide QRS complexes and eventually a sine wave—fits hyperkalemia exactly. ST-segment elevations point to myocardial infarction, prolonged QT with U waves is typical of hypokalemia, and Osborn waves occur with hypothermia, not hyperkalemia. In practice, recognizing this sequence helps prompt urgent management to stabilize the myocardium and shift or remove potassium.