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Pressure-volume loop and decreased venous compliance

Discussion in 'Medical Students - MD' started by rsweeney, Mar 27, 2004.

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  1. rsweeney

    rsweeney Senior Member
    15+ Year Member

    Jan 6, 2003
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    When analyzing the pressure-volume loop for decreased venous compliance, would afterload be increased or decreased? Here is where I am at mentally. Decreased venous compliance-->decreased pooling-->greater amount of blood that returns to the heart--> increased filling-->increased preload-->frank-starling mech. activated so contractility increases thus you have an inc. in stroke volume-->increased cardiac output--> higher areterial pressure thus increased afterload.

    BUT: When you analyze the pressure-volume loop for decreased venous compliance the end diastolic volume is increased [as it should be] and end systolic volume is decreased [as it should be due to inc. cardiac output]---but according to my reasoning afterload should be increased due to inc. cardiac output.

    I thought that on a pressure-volume loop diagram afterload-increases are represented by a shift to the RIGHT along the end-systolic volume-pressure (ESVP)curve. But the actual PV-loop diagram for decreased venous compliance has a shift to the LEFT down the ESVP curve. What's going on or what am I missing??:(

    So an increase to the right or left along the ESVP curve won't necessarily tell you whether you have an increase or decrease in afterload? Is this true?
    -Thank you for any help:)

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  3. DrMom

    DrMom Official Mom of SDN
    Physician Moderator Emeritus 10+ Year Member

    Apr 24, 2002
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    Attending Physician
    duplicate. closing

    open one is in dental forum
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