More Murmur Quetions -- help

Discussion in 'Step I' started by bt9099, Jun 17, 2008.

  1. bt9099

    2+ Year Member

    Mar 30, 2008
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    More cramming, thanks for the help.

    1. In HCM, why is the ejection murmur increased upon decreased venous return?

    2. In mitral stenosis, why is that the SHORTER the time from S2 to the opening snap the MORE SEVERE the stenosis? WOuldnt it be the opposite, meaning that the later the opening snap means that the valve is having that much more difficulty opening up????

  2. obiwan

    obiwan Junior Member
    10+ Year Member

    Mar 26, 2006
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    Attending Physician
    1. The murmur in hypertrophic CM is due to the anterior leaflet of the mitral valve drawn against the hypertrophied septum causing a murmur that is similar to that of aortic stenosis. With decreased venous return, the left ventricle isn't as filled up and the leaflet is drawn closer to the septum which causes more obstruction. that is why treatment for HCM is to allow adequate ventricular filling so there is less outlet obstruction.

    Feel free to correct if i'm missing something.
  3. penguinophile

    penguinophile MetalHead
    Moderator Emeritus SDN Advisor 10+ Year Member

    Jun 16, 2005
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    Resident [Any Field]
    2. Remember that there is pressure building up behind the stenotic valve. Even though you may think that earlier snap = a less stenotic valve, what it really means is that LA pressure has built up so much that it overcomes the stenosis rather quickly (remember that the opening snap is occurring during passive filling, not during atrial contraction, so the fact that it has pressure built up at that point is saying something). Think about the severity of the stenosis in terms of what is happening behind it (what affects things clinically such as pulmonary edema and possible A-fib) instead of how stiff the mitral valve is itself. does that make sense?

    Lilly's Pathophys of Heart Disease has an awesome valvular heart disease chapter that I would suggest reading if you know of anyone who has the book.
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  4. R_C_Hutchinson

    R_C_Hutchinson Senior Member
    7+ Year Member

    Aug 16, 2003
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    Great explanation, thanks for this!

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