II. Pathophysiology
- S3 sound represents rapid passive ventricular filling
- Occurs as ventricles start to expand during early diastole
- Outside of normal causes (see below), typically represents ventricular overfilling
- Associated with a dilated ventricle and Systolic Dysfunction
III. Signs
- S1, S2, S3 sound like "Ken-tuck-y" (lub-dub-dub)
- Left Ventricular S3
- Heard best at apex, with patient in left lateral decubitus position, during expiration (breath held)
- Accentuated with isometric hand grip
- Right Ventricular S3
- Heard best at the left sternal border, with patient supine, during inspiration
- Accentuated with passive leg raise
- May be associated with Jugular Venous Distention
IV. Causes
- Normal
- Age under 40 years (esp. children and young adults)
- Third Trimester of pregnancy
- Left or Right Ventricle Volume Overload
- Mitral Regurgitation
- Tricuspid Regurgitation
- Congestive Heart Failure
- Ventricular Septal Defect
- Patent Ductus Arteriosus
- Constrictive Pericarditis
- Hyperkinetic cardiac activity
V. Resources
- University of Michigan Heart Sound and Murmur Library
- Silverman in Walker (1990) The Third Heart Sound, Clinical Methods, 3rd ed