Certain heart sound configurations mimic a split second heart sound.
One of these conditions is a late systolic click plus a single second heart sound (S2). Since the late systolic click occurs just before the S2 it is easy to confuse the two with a split S2.
Listen carefully to the two sounds. If the first of the pair is of higher frequency and shorter duration than the second, it is a late systolic click followed by a single second heart sound.
Another way of distinguishing a late systolic click from a split S2 is to move the stethoscope head to the pulmonic area. The late systolic click will disappear and you will only hear the single S2.
A late systolic click is caused by degeneration of the mitral valve leaflets. This degeneration causes the closing of the leaflets to make a "clicking" sound during late systole.
On the anatomy video you will see prolapse of the anterior lateral mitral valve leaflet which is the cause of the late systolic click.