heart sounds

Question 1

cause of heart sounds in general

Answer 1

turbulent blood flow
tensing of cardiac structures
valve closure

Question 2

cause of S1 heart sound

Answer 2

AV (tricuspid and mitral) valve closure

Question 3

what phase of cardiac cycle is S1

Answer 3

start of systole - isovolumic contraction

Question 4

phases of the cardiac cycle

Answer 4

isovolumic contraction - period between which AV valves shut, SL valves open; ventricles contracting in a closed circuit
rapid ejection - opening of SL valves; c wave in JVP
reduced ejection - slowing of ejection ultimately causing closure of SL valves (aortic and pulmonary trunk pressures >ventricular pressure)
isovolumic relaxation - relaxation of ventricles when both AV and SL valves are shut; V wave in JVP
rapid ventricular filling - AV valves open causing rapid filling; y descent in jvp
diastasis - as filling of ventricles nears ~80%
atrial systole - atria contract to top of the ventricles with last amount of blood; a wave in jvp

Question 5

cause of S2 heart sound

Answer 5

SL (pulmonary and aortic) valve closure

Question 6

what phase of cardiac cycle is S2

Answer 6

end of systole/beginning of diastole - isovolumic relaxation

Question 7

cause of S3 heart sound

Answer 7

volume overload
tensioning of chordae tendinae at the end of rapid ventricular filling
sudden deceleration of blood against LV

Question 8

cause of S4 heart sound

Answer 8

pressure overload

reflection of atrial wave against a poorly compliant ventricle (thickened or stiff)

Question 9

pathologies where S4 is seen

Answer 9

LV hypertrophy secondary to HTN
aortic stenosis,acute MR
IHD, age +++
angina, MI sometimes - only thing seen acutely

Question 10

pathologies where S3 is seen

Answer 10

normal in young people and athletes
in older people - congestive heart failure
physiological - thyrotoxicosis, pregnancy