Heart murmurs/sounds

Discussion in 'Step I' started by SeventhSon, May 8, 2008.

  1. SeventhSon

    SeventhSon SIMMER DOWN

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    Hi guys, i'm wondering if anyone has an explanation for why heart murmurs get louder or worse with inspiration vs. expiration vs. amount of preload (is the effect of inspiration/expiration just increasing the preload/afterload?)

    According to Goljan, I believe...

    left-side S3 heard best on expiration
    aortic stenosis heard best on expiration
    mitral regurg. heard best on expiration
    aortic regurg best heard on expiration

    tricuspid regurg best heard on inspiration
    right-side S3 best heard on inspiration

    MVP heard closer to S1 with dec. PL, closer to S2 with inc. PL

    anyone explain?
     
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  3. SeventhSon

    SeventhSon SIMMER DOWN

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    ok i stopped being lazy and thought aobut it a little...

    expiration = increased afterload, and to me it makes sense this would cause aortic stenosis and mitral regurg to be more prominent

    inhalation = blood pools in the lungs, expiration = blood pooled in lungs is released to left heart, hence a "thud" in early diastole for your left-sided S3

    inhale = inc. PL to right heart = early diastolic right heart thud in R heart failure
     
  4. agranulocytosis

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    I'm not sure if this is correct, but it's simplified things for me when I think through questions and has helped me with the basis for the heart sounds...

    Left-sided heart sounds are best on expiration b/c it moves the heart closer to the chest wall. Right-sided heart sounds are best heard with inspiration b/c of increased preload due to negative intrathoracic pressure.
     
  5. DocKat

    DocKat Member

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    i agree...sorting the heart sounds according to left or right really helps me out.

    this is what i think...most likely incorrect, but helps me remember

    left-sided heart sounds increase on expiration because during expiration, you are pushing your blood out into the systemic circulation (more intrathoracic pressure), thus there is more blood flow through the left side of the heart--> louder heart sounds

    right-sided heart sounds increase on inspiration because during inspiration the blood is increased to the heart (less intrathoracic pressure), thus there is more blood flow through the right side of the heart--> louder heart sounds
     
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