Complex sentence: In individuals with an ASD, a fixed splitting of S 2 occurs because the extra blood return during inspiration gets equalized between the left and right atria due to the communication that exists between the atria in individuals with ASD.
Split into simpler sentences: In individuals with an ASD, there is a fixed splitting of S 2. The reason that there is a fixed splitting of the second heart sound is that the extra blood return during inspiration gets equalized between the left and right atrium due to the communication that exists between the atria in individuals with ASD.