What causes a split S2 sound on auscultation?

A split S2 is the result of the slightly delayed closure of the pulmonary valve following the closure of the aortic valve. It is normally heard in deep inspiration as a decrease in intrathoracic pressure causes an increase in right-sided venous return, which leads to greater right ventricular systole and as a result a delayed closure of the pulmonary valve.

A split S2 may be caused by an underlying pathology such as pulmonary stenosis, RBBB, atrial septal defects (fixed split S2), pulmonary hypertension (fixed split S2), right-sided heart failure (fixed split S2), LBBB (paradoxical S2 (P2 before A2)), aortic stenosis (paradoxical S2 (P2 before A2)), or right ventricular pacemaker (paradoxical S2 (P2 before A2)).

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This post was written by Kelly Clinning