What can the presence of peaked T-waves indicate?

Peaked T-waves on an electrocardiogram (ECG) are characterized by their sharp, tall appearance and are primarily associated with hyperkalemia, which indicates elevated potassium levels in the blood. This feature is an early sign of hyperkalemia because as potassium levels rise, there is a direct effect on cardiac myocytes, leading to changes in repolarization and manifesting as peaked T-waves on an ECG.

In the context of hyperkalemia, increased extracellular potassium causes a reduction in the resting membrane potential, which affects the action potentials and repolarization of the cardiac cells. This alteration in electrical activity first manifests as tall, narrow peaked T-waves before other more serious alterations occur, such as QRS widening or loss of P waves. Thus, when peaked T-waves are observed, they can serve as a critical early marker for assessing potassium levels and potential cardiac complications related to hyperkalemia.

Other conditions listed, such as hypokalemia, acute myocardial infarction, and acute pericarditis, have distinct ECG changes that do not typically include the presence of peaked T-waves as a primary finding. For example, hypokalemia usually presents with flattened T-waves or U waves, while acute myocardial infarction