S3 - Third Heart Sound

S3	Ventricular Gallop (diastolic)
cardiac cycle	Proto-diastolic (0.14 to 0.16 seconds after A2).
character	Low-pitched sound (end of rapid filling)
Auscultation	Bell (after coughing). S1---S2 -S3 'lub duppa' Left S3 = apex, expiration, left lateral decubitus. Right S3 = left sternal border or xiphoid, inspiration.
Comments	Normal in young people. Indicates ventricular decompensation. Worst prognosis than S4.