DR Medhat MRCP

Heart sounds
S1 During ventricular systole .
Caused by closure of mitral and tricuspid valves.
S2
Soft if long PR or mitral regurgitation.
Loud in mitral stenosis , atrial premature beats & left to right shunt.
During diastole, Caused by closure of aortic and pulmonary valves.
Mnemonics :
Loud in HTN
Soft in A.S
Reversed split (left) in LBBB.
Widely split (right) in RBBB.
Fixed split (in the middle) in ASD.
S3 Caused by diastolic filling of the ventricle (heard after S2)
Considered normal if < 40 years old (may persist in women till 50 yrs old)
Heard in left ventricular failure (e.g. dilated cardiomyopathy), constrictive
pericarditis (called a pericardial knock)
S4 Caused by atrial contraction against a stiff ventricle (heard before S1)
Heard in aortic stenosis, HOCM, HTN (S4 = back pressure overload)
In HOCM a double apical impulse may be felt as a result of a palpable S4
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