Step I two heart sounds

[trgf]

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given that atrial septal defects produce 2 major heart murmurs - through the atria and pulmonary valves -which one is systolic and which one is diastolic?

 

[Step1Hash]

I'm not 100% sure but this is what I think happens. The passage of blood through the ASD occurs when the pressure in the L is greater than the R. This is constantly the case BUT the gradient isn't large enough to cause a murmur (if there was a murmur I would think it would be during both systole and diastole but greatest in diastole when the atria contracts). Thus you only hear one murmur during an ASD which is a flow murmur at the pulmonic valve during systole due to the increased blood in the right side of the heart.

Someone correct me if I am wrong though...hope this helps.

 

[dienekes88]

pulmonary flow murmur (cresc/decresc at LUSB). fixed split S2.

no diastolic murmur.

 

[trgf]

http://books.google.com/books?id=35...wAA#v=snippet&q=a large left-to-right&f=false

Quote (from bottom of page 222 right column, second to last paragraph)
"A large left to right shunt associated with atrial septal defect may cause mid-diastolic murmurs owing to increased flow across the tricuspid valve."

 

[ArcGurren]

The question stem will usually give you more information about the murmur than just letting you hear it; otherwise it's tough to differentiate it from other murmurs (fixed splitting of S2, oxygen saturation increased in the right atrium, premature infant or something with IRDS - in this instance you can definitely differentiate it from PDA which could also happen since PDA is continuous and "machine like")

 

[hyrule]

There's no way they would test you on ASD murmurs with audio. They'd probably give you a clinical scenario describing fixed splitting.