What can also lead to an inverted T wave on an ECG aside from ischemia?

Inverted T waves on an electrocardiogram (ECG) can be indicative of several underlying conditions beyond ischemia. Hyperkalemia, for instance, is one commonly known cause; however, hypokalemia can also lead to alterations in the cardiac electrical activity resulting in T wave inversion.

Hypokalemia, or low potassium levels in the blood, disrupts the normal repolarization process in cardiac myocytes. Potassium is crucial in maintaining the resting membrane potential and the proper function of the cardiac action potential. When potassium levels are low, it can cause the repolarization of the heart cells to become abnormal, leading to inverted T waves. This is especially relevant in cases of severe hypokalemia, and the inverted T waves tend to be more prominent in certain leads of the ECG.

In contrast, hyperkalemia usually causes tall, peaked T waves rather than inverted ones, while bradycardia primarily affects the rate at which the heart beats without typically causing T wave inversion. ST segment elevation is another separate phenomenon often associated with acute myocardial infarction but does not directly cause T wave inversion. Each of these factors plays distinct roles in cardiac conduction and repolarization, ultimately influencing the ECG readings in specific ways.