In hyperkalemia, what ECG changes progress?

• A. Peaked T waves → widening QRS → potential sine wave
• B. Flat P waves → prolonged QT
• C. ST elevation with PR prolongation
• D. Low voltage QRS

Answer: (A)

Potassium excess changes how heart muscle cells conduct electricity. Early on, higher extracellular potassium speeds up repolarization, which shows up as tall, peaked T waves on the ECG. As the potassium level rises further, conduction through the atrioventricular node and ventricles slows, so the QRS complex widens. In severe hyperkalemia, this progression can continue until the QRS and T waves merge into a sine-wave pattern, a dangerous rhythm that can lead to arrest. That sequence—peaked T waves followed by QRS widening and potentially a sine wave—is the classic ECG progression with hyperkalemia. The other patterns described are not characteristic of hyperkalemia: flat P waves with a prolonged QT are more typical of hypokalemia, ST elevation with PR prolongation points away from hyperkalemia, and low voltage QRS is seen in other conditions like large effusions or obesity.