Left ventricular S3 is seen in -
S3 is ventricular gallop Occurs due to increased blood volume in ventricles during early diastolic filling phase. In MR, during systole, blood goes into LA, but during diastole this blood comes along with normal blood to the LV. Hence producing S3 Ref: Harrison's 20th edition pg 1445
AS
MS
MR
ASD
C.V.S