NCIt definition : A finding which can be heard on auscultation of the heart in the setting of congestive
heart failure. The sound of the S3 gallop, which immediately follows the second heart
sound (S2) is thought to be produced by the sound of blood flowing into a noncompliant
ventricle.;
Alternative definition : CDISC: Presence of mid-diastolic heart sound.; ACC/AHA: An auscultated finding describing a low-frequency sound that follows A2 in
early diastole and corresponds with the first phase of rapid ventricular filling,
signifying the third heart sound. It is normal in children and young adults, but abnormal
in others.; ACC/AHA: Presence of a third (mid-diastolic) heart sound.;