For heart sounds listen to the synthetic sound while reviewing this lesson.
An opening snap occurring early in diastole along with a single second heart sound can mimic a split second heart sound.
An opening snap is caused by thickened valve leaflets. When they open it produces a snapping sound.
The more severe the thickening the earlier in diastole the opening snap occurs. In this example you are hearing an opening snap which occurs 75 milliseconds after the start of the second heart sound.