Split S2

Article summary

of various events of a cardiac cycle, with 2nd heart sound at bottom. A split S2 is a finding upon auscultation of the S2 heart sound. It is caused when the closure of the aortic valve (A 2 ) and the closure of the pulmonary valve (P 2 ) are not synchronized during inspiration. The second heart sound (S2) is caused by the closure of the aortic and pulmonic valves, which causes vibration of the valve leaflets and the adjacent structures. The aortic valve closes slightly before the pulmonic, and this difference is accentuated during inspiration when S2 splits into two distinct components (physiological splitting). During expiration, the pulmonic valve closes at nearly the same time as the aortic, and splitting of S2 cannot be heard. Exercise increases the intensity of both the aortic and pulmonic components of S2, whereas deep inspiration increases the intensity of the pulmonic component only.

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