The Graham Steele murmur is the murmur of pulmonic valve regurgitation.  Pulmonic regurgitation produces a murmur that is often indistinguishable from that of aortic valve regurgitation.

Pulmonic valve regurgitation produces a soft, high-pitched, early diastolic decrescendo murmur heard best at the pulmonic listening post (left-upper sternal border).  The murmur of pulmonic regurgitation increases in intensity during inspiration, unlike that of aortic regurgitation.