What clinical sign might be observed with pulsus alternans?

Pulsus alternans is characterized by a regular alternating pattern of strong and weak heartbeats, and it is typically associated with heart failure, particularly in cases of left ventricular dysfunction. The presence of a third heart sound (S3) is indicative of heart failure and is often heard in conjunction with pulsus alternans.

The S3 sound occurs due to rapid ventricular filling during early diastole, which can indicate increased volume or pressure in the ventricles, often seen in congestive heart failure. When pulsus alternans is present, it signifies that the heart is struggling to maintain adequate perfusion, leading to this characteristic sound being audible during auscultation.

In this context, the correlation between pulsus alternans and the third heart sound reflects the underlying cardiac dysfunction, making the identification of S3 a significant clinical sign when assessing a patient with this condition.