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In U-world , it is mentioned that S3 heart sound is produced by the reduced intrinsic ventricular wall compliance (eg. restrictive cardiomyopathy)
BUT,
In Kaplan, it is mentioned that S3 heart sound is produced by the rapid expansion of a very compliant ventricle (as in children & young adult).

So, these 2 are opposite. Same S3 sound in compliant ( kaplan)& non-compliant(u-world) ventricles. Very confused.Can anybody pls clarify this.
 

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Source: Wikipedia

S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by the inflow of blood from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably because during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation. It may also be a result of tensing of the chordae tendineae during rapid filling and expansion of the ventricle.

Associations:

1.Rapid ventricular filling- Mitral regurgitation,Ventricular septal defect

2.Poor left ventricular function- Post MI,

Dilated cardiomyopathy - the ventricular walls are abnormal for a variety of reasons, and become thin and stiff so do not relax well.

S3 can also be due to tricuspid regurgitation, and could indicate hypertensive heart disease.

In conditions affecting the pericardium or diseases that primarily affect the heart muscle (restrictive cardiomyopathies) a similar sound can be heard, but is usually more high-pitched and is called a 'pericardial knock'.
 

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That means there is no hard and fast rule, that S3 is produced in very compliant ventricle or non-compliant ventricle ie It can be produced in both cases.Is my understanding right? Pls correct me if I am wrong.
 

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That means there is no hard and fast rule, that S3 is produced in very compliant ventricle or non-compliant ventricle ie It can be produced in both cases.Is my understanding right? Pls correct me if I am wrong.
I Just had the same doubt, when I came across this question. Apparently, S3 and S4 can both be a sign of ventricular non-compliance, the difference being the phase of the cardiac cycle they occur in.

So, this is from a table in UWorld: -

S3 (although much common in dilated ventricles)
  • Restrictive cardiomyopathy (eg. amyloidosis)
  • Age > 40ys
  • High output states (HFailure, DCM)
  • Pregnancy
 
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