heart sounds Flashcards
heart sounds
- Valve closure produces two normal heart sounds
- The first heart sound (S1) or ‘lub’ is caused by closing of the AV valves
- The second heart sound (S2) or ‘dub’ is caused by closing of the aortic and pulmonary valves
But it’s not the valves closing that you hear…
YOU HEAR THE BLOOD (TURBELENT) - BLOOD BOUNCES AGAINST VALVE
To hear blood
it must be turbulent…
When the valves close blood bounces against them, creating turbulence, which you can hear
When do the valves close?
Both left & right AV valves close at the beginning of systole = S1 (‘lub’)
Aortic & pulmonary valves close at the end of systole = S2 (‘dub’)
Opening of the valves does not cause any sound
Heart sounds: the extra ones
S3
Two other heart sounds can sometimes be heard:
• The third heart sound (S3) marks end of rapid filling phase in early diastole, and is due to “recoil” of blood from ventricular wall
Heart sounds: the extra ones
S4
• The fourth heart sound (S4) coincides with atrial contraction (late diastole), it is not normally heard, but can indicate pathology involving strong atrial contraction
Heart murmurs: the sounds of pathology
Healthy valves appose their edges efficiently, but several diseases, including bacterial infections and congenital malformations, may deform valves, affecting their opening and/or closing
heart mumors
Failure of valves to close or open properly creates abnormal turbulence: Heart murmurs
• Regurgitation or insufficiency - when valves cannot close tightly, blood flows through the resulting gaps in wrong direction
• Stenosis - when the passages containing valves decrease in size, blood flow in the correct direction is impeded
Type and timing of murmurs can indicate type of pathology
‘Lub-whistle-dub’ = aortic stenosis ‘Lub-swish-dub’ = mitral regurgitation ‘Lub-dub-swish’ = aortic regurgitation ‘Lub-dub-whistle’ = mitral stenosis
‘whistle’ throughout = patent ductus arteriosus
