Which of the following describes the typical ECG signs of hyperkalemia?

• A. ST-segment elevation in leads
• B. PR prolongation
• C. Tall, peaked T waves; progression to widened QRS and sine wave at severe levels; PR prolongation.
• D. Q waves in abnormal leads

Answer: (C)

Hyperkalemia changes the heart’s electrical activity by increasing extracellular potassium, which speeds up repolarization but slows conduction through the heart. The first clue is tall, peaked T waves from faster repolarization. As potassium rises further, conduction through the atrioventricular node slows, so the PR interval lengthens. With even higher levels, ventricular conduction slows more and the QRS complex widens. In severe hyperkalemia, the QRS and T waves can merge into a sine-wave pattern, signaling a high risk of dangerous arrhythmias. The described signs—tall, peaked T waves; progression to widened QRS and sine wave at severe levels; and PR prolongation—fit this progression and are classic for hyperkalemia. Other findings like ST-segment elevations or Q waves point to different conditions (such as myocardial infarction or prior infarct) and do not describe the typical hyperkalemia pattern.