Apex: Late Systolic Murmur

A late systolic murmur begins in the latter half of systole, peaks in the later third of systole, and extends to the second sound. It is commonly heard in mitral valve prolapse which has a murmur high in frequency, blowing in quality, and heard best with the diaphragm at the apex. It radiates to the axilla or left sternal border.

The sound you heard is a late systolic murmur. The murmur is added and then removed from the cycle.