heart sounds Flashcards
when is S1 heard?
- when the mitral and tricuspid valves close at the beginning of ventricular systole
where is S1 best heard?
in the apex
where do you listen for mitral stenosis?
in the apex area over the mitral valve
how do you enhance the intensity of S1 in mitral stenosis?
by rolling the patient onto their left hand side
what can cause a quiet S1?
- low CO
- poor left ventricular function
- rheumatic mitral regurgitation
- long P-R interval (first degree heart block)
what can cause a loud S1?
- increased CO
- large SV
- mitral stenosis
- short P-R interval
- atrial myxoma (rare)
what can cause a variable S1?
- AF
- extrasystoles
- complete heart block
when is S2 heard?
- closure of aortic and pulmonary valves at the end of systole
where is S2 best heard?
at the left sternal edge
why does S2 splitting occur?
- because left ventricular contraction slightly precedes that of the right ventricle so that the aortic valves close before the pulmonary valve
- the splitting increases at end-inspiration because increased venous filling of the right ventricle further delays pulmonary valve closure
- lub d-dub
when might the aortic component of S2 be quiet or absent?
- in calcific aortic stenosis
- aortic regurgitation
when might the aortic component of S2 be loud?
- systemic hypertension
when might the pulmonary component of S2 be loud?
- pulmonary hypertension
when would wide splitting of S2 but normal resp variation occur?
- right bundle branch block
- pulmonary hypertension
when would fixed splitting of S2 with no variation in resp occur?
- atrial septal defect
when/where is S3 best heard?
- low-pitched early distolic sound heard best at the apex
- coincides with rapid ventricular filling immediately after the opening of the AV vales
- lub-dub-dum
is S3 normal?
- yes, in young adults and during pregnancy
- pathological after the age of 40
what are the most common pathological causes of S3?
- left ventricular failure
- mitral regurgitation
when/where is S4 heard?
- soft and low-pitched
- heard at apex
- occurs just before S1 (da-lub-dub)
is S4 pathological?
- yes, always
what causes S4?
- forceful atrial contraction against a non-compliant or stiff ventricle
- often heard with left ventricular hypertrophy
when can S4 not occurs?
- with AF
when might a snap be heard and what is it?
- mitral stenosis
- results from a sudden opening of a stenosed valve and occurs in diastole, just after S2
- best heard at the apex
when are murmurs heard?
- when there is turbulent blood flow across an abnormal valve, septal defect or outflow obstruction
