aortic regurg and pressure changes

Discussion in 'Step I' started by studylol, 09.29.14.

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  1. studylol

    studylol 2+ Year Member

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    What happens to Aortic Systolic Pressure in Aortic Regurgitation? And another question asking the same thing about diastolic.

    I think during diastolic, it would decrease. When normal, the pressure typically increases right as the aortic valve closes due to the momentum that the blood carries. If this momentum is able to carry blood back into the ventricle due to a dysfunctional valve, then the pressure should no longer increase, but decrease.

    During systole i'm having more trouble with imagining the mechanics. I'm tempted to say that there should be no change because a floppy valve won't change how much blood the ventricle pumps out, would it? However, according to the brosencephalon deck (which may be inaccurate), it increases.

    Am I right about diastolic? How does it change during systole?
     
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  3. seminoma

    seminoma 2+ Year Member

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    Acute aortic regurg will lower SBP because of decreased SV.
    Chronic aortic regurg will raise SBP because the volume overload eventually causes LVH.

    Edit: Just realized you didn't ask what I answered. Sorry. The floppy valve doesn't directly change how much blood is pumped, but it indirectly changes starling dynamics leading to what I originally typed above.
     
    Last edited: 09.29.14
  4. studylol

    studylol 2+ Year Member

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    Thanks that answers my question!
     
  5. SBR249

    SBR249 7+ Year Member

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    Aortic regurgitation will increase systolic pressure in the acute situation. The reason is that the backflow of blood during diastole leads to increased end diastolic volume in the LV (essentially increased preload). This increased preload will increase stroke volume according to the Frank-Starling mechanism causing an increase in systolic pressure.

    In the long term, the chronic extra work of pumping the larger volume of blood would lead to left-sided heart failure and a decrease in systolic pressure.

    Source: http://www.cvphysiology.com/Heart Disease/HD005.htm
     
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  6. thehundredthone

    thehundredthone 2+ Year Member

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    Actually acute AR decompensates quickly, and leads to hypotension. You see this in endocarditis, dissection, trauma etc. There isn't enough time for Starling dynamics to cause systolic hypertension. Most acute valvular pathologies tend to decompensate rapidly because it takes time for the chambers to adjust. (a parallel can be drawn to tamponade where even 50 mL is enough to precipitate it vs. close to a liter being asymptomatic in chronic effusions)

    Early on in chronic AR though, what you said holds true, with the Frank-Starling mechanism being the cause of the increased systolic blood pressure. As the ventricle compensates for the volume overload (through dilation and eccentric hypertrophy), the filling pressures fall, and the systolic pressure is no longer as high. If decompensation occurs in chronic AR it's due to pressure overload (diastolic failure due to noncompliant hypertrophic ventricle).

    http://circ.ahajournals.org/content/112/1/125.full
     
  7. SBR249

    SBR249 7+ Year Member

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    Perhaps I was a little loose with my terminology.

    Chronic AR is about the only one that the Step actually cares about and can be considered a compensated sequela of acute AR if the patient survives. This is the one with the widened pulse pressure, bounding pulses, de Musset's sign, etc. In that context, in the short term, systolic pressure is increased and in the long term, systolic pressure is decreased.
     
  8. drryan123

    drryan123

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    They won't ask you about systolic pressure in AR because it is highly variable. Most patients with acute AR are in respiratory distress. They have HTN but it has nothing to do with the valve lesion -> it's from the high sympathetic tone. Pulmonary edema for any reason usually results in HTN. Think about what your BP would do if you felt like you couldn't breathe. In chronic AR the systolic BP depends on a multitude of factors including how well the ventricle is compensating. BP is not reliably high or low. Would not be a fair thing to ask about. I say these things as a cardiologist who treats this lesion commonly.

    The main feature of AR the boards will test is the low diastolic BP and hence high pulse pressure. This is a pretty reliable finding with a clear underlying mechanism that the boards like to go after. Good luck in your studies.

    Dr. Jason Ryan
    www.boardsbeyond.com
     
  9. Phloston

    Phloston Lifetime Donor 2+ Year Member

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    The only things you need to know about aortic regurg for Step 1:

    - AR + MVP = murmurs in Marfan's (had one on my Step 1; had to move the steth to get it right).
    - MASSIVE pulse pressure (i.e., huge difference between systolic and diastolic)
    - Bounding pulses
    - Diastolic murmur
    - Causes increased preload on LV; therefore LVH due to volume, not pressure, overload. Therefore intra-LV pressure greater in AS than AR.
    - Tx is valve replacement (AR/AS you must replace valve; MR/MS you try fixing it before replacing it).
     

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