Spilt of S2

Physiologic Split S2

This happens during inspiration when increased venous return to the right side of the heart delays the closure of the pulmonic valve (major effect), and decreased return to the left side of the heart hastens the closure of the aortic valve (minor effect), thereby further separating A2 and P2.

Split is best commented in Pulmonary area

Abnormal spilts 

 different types of split S2 can be associated with medical conditions:

Wide splitting: seen in conditions that delay RV emptying (pulmonic stenosis, right bundle branch block). 

Delay in RV emptying causes delayed pulmonic sound (regardless of breath); it is an exaggeration of normal splitting sounds

Split during expiration: Reverse splitting (paradoxical splitting) indicates pathology due to delay of aortic valve closing. Aortic stenosis, hypertrophic cardiomyopathy, left bundle branch block (LBBB), and a ventricular pacemaker could all cause a reverse splitting of the second heart sound. Here P2 is early and A2 is late.

Split during both inspiration and expiration:If splitting does not vary with inspiration, it is termed a "fixed split S2" and is usually due to a septal defect,[5] such as an atrial septal defect (ASD). The ASD creates a left to right shunt that increases the blood flow to the right side of the heart, thereby causing the pulmonary valve to close later than the aortic valve independent of inspiration/expiration.

A bundle branch block either LBBB or RBBB, (although RBBB is known to be associated only with S1 split), will produce continuous splitting but the degree of splitting will still vary with respiration.