Heart Sounds

S1, S2, S3, S4

S1 & S2 are normal

S3 & S4 may indicate heart disease or may be normal in some populations

Systole = onset of S1 to onset of S2

Diastole = onset of S2 to next onset of S1

S1 heart sound ("Lubb")

Tricuspid & Mitral valve closure in systole

- mitral closes prior to tricuspid

- mitral closure in louder due to exposure to higher pressure fluctuations

- "Lubb" sound

- best heard over left ventricle, Apex of the heart (5th IC & midclavicular)


- S1 may split due to mitral & tricuspid closing at slightly difference times

- auscultate at 3rd, 4th, 5th IC to right of sternal border

- use diaphragm side of stethoscope

S2 heart sound ("Dubb")


Aortic & Pulmonic valve closure during the onset of diastole

- "Dubb" sound transmitted through great vessels

- aortic valve closes prior to pulmonic and thus a split can often be heard

- loudest at right sternal border, 2nd IC space


- best heard at second or 3rd IC space to left of sternal border (pulmonary area)

- splitting is augmented during inspiration

- normal in healthy teenagers in supine

S3 heart sound ("Lubb-Dubb-Dubb)

Vibrations due to ventricular rapid filling prior to atrial contraction

- If S3 is heard it is usually during early diastole a fraction of second after S2

- in Children S3 is normal

- in middle age or older is associated with left ventricular failure and congestive heart failure

- also termed ventricular gallop, diastolic gallop, abnormal S2, proto diastolic gallop

- Heard in apex of heart if supine or left lateral position

- use the bell of the stethoscope

- may sound like "Kentucky"

S4 heart sound ("La-Lubb-Dubb")

Stiff ventricular wall causes vibration as ventricular fills after atrial contraction

- occurs during ventricular diastole

- often heart in patients with HTN, CAD, elderly

- use bell of scope over apex if heard in left ventricle

- place bell over right ventricular area which is the lower left sternal border if right ventricle is involved

- louder in inspiration

- may sound like "Tennessee"