Normally, the aortic valve closure (A2) is followed by the pulmonic valve closure (P2) but the A2-P2 interval increases with inspiration and decreases with expiration. With paradoxical splitting, there is a delay in the closure of the aortic valve, so that A2 can follow P2; the individual components can be appreciated at the end of expiration and the interval narrows with inspiration (which is the oposite of the normal pattern). [from
HPO]