This is a graphic example of S2 split in expiration.

One type of expiratory splitting is paradoxical splitting of the second heart sound. It occurs whenever the aortic closure sound is significantly delayed. During inspiration, the sounds fuse as P2 is also delayed. During expiration, pulmonary closure precedes the delayed A2. Causes of paradoxical splitting include electrical and mechanical delays, such as left bundle branch block and aortic stenosis.