50. What normal cardiac finding can mimic an S3 heart sound?

A. Split S2

B. Split S1

C. S4

D. Systolic ejection click

S3 is a low-pitched sound. This is helpful to distinguish an S3 from a split S2, which is high-pitched. An S3 heart sound should disappear when the diaphragm of the stethoscope is used and should be present while using the bell. The opposite is true for a split S2. Also, the S3 sound is heard best at the cardiac apex while a split S2 is best heard at the pulmonic listening post (left upper sternal border). To best hear an S3, the patient should be in the left lateral decubitus position.