All of the following statements about third Hea sound (S3) are true, except
A third hea sound (S 3) is often heard in large left-to-right shunts caused by high flow across the mitral valve with VSD or patent ductus aeriosus and with high flow across the tricuspid valve with ASD.In constrictive pericarditis, an early prominent sound of a somewhat higher frequency is heard - called the "pericardial knock, which is considered as a variant of S 3.(Hursts)The third hea sound (S 3 ) occurs during the rapid filling phase of ventricular diastole. (Harrison's). The 'rapid filling phase' (mid-diastole) begins when the tricuspid and mitral valves open. Ventricular filling occurs passively in this period. "Presystole" begins with atrial contraction and occurs just before the first hea sound. Active filling from atrial systole contributes about 20% of the blood volume to the ventricles during diastole (in contrast with the 80% from rapid, passive filling in mid-diastole).The first option mentions 'ventricular filling during atrial contraction'. Hence, it is the answer.Ref : Hurst 13/e p287; Harrison 18/e p1827
Occurs due to rapid filling of the ventricles during atrial systole
Seen in in constrictive pericarditis
Seen in Atrial Septal Defect (ASD)
Seen in Ventricular Septal Defect (VSD)
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