S3 and ASD

[Step1Hash]

Could someone explain this to me....why would a L-->R shunt like an ASD lead to an S3 heart sound? Wouldn't that decrease ventricular filling?
.. or is the L-->R shunt eventually leading to blood returning to the RA leading to the increased ventricular filling?

Thanks in advance.

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[Sheldor]

Could someone explain this to me....why would a L-->R shunt like an ASD lead to an S3 heart sound? Wouldn't that decrease ventricular filling?
.. or is the L-->R shunt eventually leading to blood returning to the RA leading to the increased ventricular filling?

Thanks in advance.

I believe an ASD leads to a fixed split S2, not an S3... Right? This is because there is more blood in the Right ventricle which means the pulmonic valve consistently takes longer to close.

 

[Step1Hash]

I believe an ASD leads to a fixed split S2, not an S3... Right? This is because there is more blood in the Right ventricle which means the pulmonic valve consistently takes longer to close.

yea you get the fixed split S2 but DIT is saying you get an S3 also with any L-->R shunt and I looked on google and websites say the same thing but don't really explain why.

 

[Sheldor]

yea you get the fixed split S2 but DIT is saying you get an S3 also with any L-->R shunt and I looked on google and websites say the same thing but don't really explain why.

I could see it with Eisenmenger's syndrome when you get a reversal of the left to right shunt, because then you would be overfilling the left ventricle. Maybe thats what they mean. Hopefully someone knows more!

 

[ih8mcat]

I think your explanation makes sense. When you have an ASD more blood is returning to the right atrium, and then the right ventricle, so s3 is increased. This is before eisenmengers complex. I would imagine one eisenmengers occurs, then you'd STILL have an S3, because now all of that blood is rushing into the left side of the heart.

Then you could ask which one would be made worse by inspiration versus expiration