What does the term "electrical alternans" indicate?

The term "electrical alternans" refers to a specific pattern observed on an electrocardiogram (ECG) and is often associated with pericardial effusion, which is a condition in which excess fluid accumulates in the pericardial space surrounding the heart. In this context, electrical alternans can manifest as alternating amplitudes of the QRS complexes or the T waves, and this pattern may indicate that the heart is swinging within the fluid-filled pericardial sac. It highlights the mechanical effects of the effusion on the heart's electrical activity, serving as an important clinical indicator that warrants further investigation.

The other choices do not accurately define electrical alternans. While tachycardia can influence ECG readings, it does not specifically correlate with the hallmark feature of electrical alternans. Similarly, while physical exercise can affect heart rhythm, it is not directly related to this term. Lastly, referring to electrical alternans as merely an electrical artifact overlooks its clinical significance and the specific conditions under which it is observed.