The T-wave changes on an ECG in the context of hyperkalemia are primarily associated with which ion?

The T-wave changes observed on an ECG in the context of hyperkalemia are primarily related to alterations in potassium levels in the body. Hyperkalemia, or elevated potassium levels in the blood, has a significant impact on the myocardial cells and their electrical activity.

As the extracellular concentration of potassium increases, it affects the resting membrane potential of cardiac cells, leading to slower repolarization during the cardiac cycle. This alteration manifests as changes in the T-wave on the ECG, typically characterized by T-wave peaking (tall, pointed T-waves) and, in severe cases, can progress to a widening of the QRS complex and other arrhythmic changes.

Understanding the relationship between potassium and cardiac electrical activity is essential in recognizing the potential life-threatening consequences of hyperkalemia, such as ventricular fibrillation or cardiac arrest. Thus, potassium is directly responsible for the T-wave changes seen in hyperkalemia, making it the correct choice in this scenario.