Heart Sounds: Stethoscope Listening
Overview of Heart Sounds (lub-du ; lub, dub )
· lub - closure of AV valves, onset of ventricular systole
· dub - closure of semilunar valves, onset of diastole
Ø Tricuspid valve (lub) - RT 5th intercostal, medial
Ø Mitral valve (lub) - LT 5th intercostal, lateral
Ø Aortic semilunar valve (dub) - RT 2nd intercostal
Ø Pulmonary semilunar valve (dub) - LT 2nd intercostals
S1 - due to closure of the AV(mitral/tricuspid) valves
- timing: beginning of systole
- loudest at the apex
S2 - due to the closure of the semi-lunar (pulmonic/aortic) valves
- timing: diastole
- loudest at the base
S3 – Ventricular Diastolic Gallop
Mechanism: vibration resulting from resistance to rapid ventricular filling secondary to
poor compliance
Timing: early diastole
Location: Apex (LV) or LLSB (RV)
Pitch: faint and low pitched
S4 - Atrial Diastolic Gallop
Mechanism: vibration resulting from resistance to late ventricular filling during atrial systole
Timing: late diastole ( before S1)
Location: Apex ( LV) or LLSB (RV)
Pitch: low ( use bell)
Heart Murmurs
Murmur - sounds other than the typical "lub-dub"; typically caused by disruptions in flow
Ø Incompetent valve - swishing sound just AFTER the normal "lub" or "dub"; valve does not completely close, some regurgitation of blood
Ø Stenotic valve - high pitched swishing sound when blood should be flowing through valve; narrowing of outlet in the open state
Pericardial Friction Rub
Ø It is an extra heart sound originating from the pericardial sac
Ø Mechanism: Originates from the pericardial sac as it moves
Ø Timing: with each heartbeat
Ø Location: over pericardium. Upright position, leaning forward
Ø Pitch: high pitched and scratchy. Sounds like sandpaper being rubbed together
Ø Significance: inflammation, infection, infiltration
