What condition is characterized by electrical alternans?

Electrical alternans refers to a specific electrocardiographic phenomenon where there is a beat-to-beat variation in the amplitude or morphology of the QRS complexes or other parts of the ECG. This condition is most commonly associated with pericardial effusion, particularly when the effusion is significant enough to cause alterations in the heart's position within the thorax. As the heart beats within a fluid-filled sac, the changing geometry can lead to this characteristic alternation in the electrical signals recorded on the ECG.

In cases of acute or significant pericardial effusion, the heart may move slightly with each heartbeat, causing the electrical signals to vary. Identifying electrical alternans is crucial because it can indicate the presence of a substantial pericardial effusion, which may lead to cardiac tamponade if not addressed promptly. The recognition of this pattern can therefore guide further evaluation and management, emphasizing the importance of timely intervention in the context of pericardial disease.