What is All of the following statements about third Hea sound (S3) are true, except: and explain in detail?
Answer is A (Occurs due to rapid filling of the ventricles during atrial systole ) Third hea sound occurs at the end of early rapid filling phase of the ventricle but not at the time of atrial systole. The hea sound associated with ventricular filling during atrial systole is the fouh hea sound (S4) Fouh Hea sound occurs in association with an effective atrial contraction() (It is presumably caused by in-rush of blood into the ventricles when the atria contracts and hence it is also called the 'Atrial Hea Sound) Pathological Third Hea Sound (S3) may be associated with ASD and VSD `A pathological S3 is often present in large left to right shunts due to high flow across the mitral valve with VSD or patent ductus aeriosus and with high flow across the tricuspid valve with ASD. The presence of this sound in these conditions does not imply congestive hea failure, and such patients may maintain normal myocardial contractility for years after the S3 is detected'- 'Hurst: The Hea' 11th/271 Congenital Hea Diseases associated with Loud S3 Ventricular septal Defect (VSD)() Patent Ductus Aeriosus (PDA)Q Atrial Septal Defect (ASD)Q Pathological Third Hea Sound (S3) may be associated with Constrictive Pericarditis Constrictive pericarditis is characterixstically associated with pericardial knock which is a distinct form of third hea sound (S3) `Pericardial knock is S3 that occurs earlier (0.1 to 0.12 after A2) and is higher pitched than normal. Its presence depends upon the restrictive effects of the adherent pericardium which halts diastolic filling abruptly'