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  #1  
Old 06-20-2011
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Default Cardiac Pressure Volume Loop Question

This dotted line is CONTROLLED LINE WHAT DOES BOLD LINE SHOWS in this picture below shows what kind of heart disease...

Cardiac Pressure Volume Loop Question-photo2440.jpg
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a) AS
b) MI
C) AI
d) MS

Last edited by INCOGNITO; 06-20-2011 at 03:48 PM.
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Quote:
Originally Posted by IKR123 View Post
This dotted line in this picture below shows what kind of heart disease...

Attachment 1581
click image to enlarge

a) AS
b) MI
C) AI
d) MS
There's impaired filling of the ventricle in this case (maybe due to loss of blood volume or valve stenosis)

I think MS will cause insufficient filling of LV.
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@ patel..
think again plz its high yield
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Quote:
Originally Posted by IKR123 View Post
@ patel..
think again plz its high yield
Thats odd.. because MS will impair LV filling so there is a decrease in EDV (Preload), and as a result the SV (Afterload) is decreased aswell.
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LV volume is dec,pressure is inc,and stroke vol is inc leading to further dec in LV volume..So i think its MR..
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@ struggle DOTTED LINE IS NORMAL (CONTROLLED) LINe
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Quote:
Originally Posted by IKR123 View Post
@ struggle DOTTED LINE IS NORMAL (CONTROLLED) LINe
OH now you say that.. lol

I think its AI ...

Aortic valve doesn't close properly so back flow of blood into the LV

FYI... the normal or Control shouldn't be that close to the right.. the normal would be more closer to the solid line..

Last edited by patelMD; 06-20-2011 at 06:39 PM.
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Old 06-20-2011
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i always have trouble reading these. correct me please if im going wrong please. the isovolumetric relaxation seems okay, the diastole (as indicated by the horizontal line below) does have an increase in volume, and in the isovolumetric contraction phase we dont see the vertical raised pressure and then the release of the aortic valve as usual. so that would mean that either the mitral or the aortic valve are opening when they shouldnt. so that would be either mitral insufficiency or aortic insufficieny? now whether it were aortic or mitral wouldnt the isovolumetric relaxation phase also be affected in both? In this, the end of systole, the pressure is lower than previous, and so im thinking lower afterload so i think maybe AI? but if you think of a Mitral Insuff (MI here) even that would lead to the same thing wouldnt it?
I think MI affects the isovolumetric contraction phase more and AI affects the isovolumetric relaxation phase more, from this source -
http://www.cvphysiology.com/Heart%20Disease/HD009c.htm
http://www.cvphysiology.com/Heart%20Disease/HD009d.htm

Okay so here lies the problem, I tend to overthink these wayy wayy too much, but im torn between the 2, and id hope theyd give us one more clue to get between them...too much of an early morning/late night rant. sorry.
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Old 06-21-2011
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I think the answer is MI.
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i think its c)..AORTIC INSUFFICIENCY
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The problem shows that no matter how much the volume of the heart increases the pressure does not increase proportionately. Which means that the compliance of the heart has increased.

a) AS - This would increase both the pressure and the volume, as the blood has no escape out of the aorta, so volume builds up but the Pressure curve would rise way above the normal, not below the normal.

b) MI - Ischemic state warrants for loss of contractality. Volume will increase, Pressure will increase or decrease depending on the severity-- in general the changes will be null because the heart has stopped pumping.

C) AI - This is the answer. The Aortic regurgitation will regurg the blood from the aorta back into the LV, increasing the volume of the LV, BUT the pressure of the LV will DECREASE because the Aortic Valve is LOOSE so its like a baloon without a knot, you fill in the water but the valve is loose so it can slide out easily, however water can come back into the baloon easily because there is no knot tied thus increasing the volume inside the baloon.

d) MS- Mitral stenosis would increase the pressure in the Left artia--back up of blood into the pulmonary system and edema-- thus dyspnea. THe volume would increase in the LEFT ARTIUM. THe picture shows LV not LA.

SO answer AI
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Quote:
Originally Posted by step1saga View Post
The problem shows that no matter how much the volume of the heart increases the pressure does not increase proportionately. Which means that the compliance of the heart has increased.

a) AS - This would increase both the pressure and the volume, as the blood has no escape out of the aorta, so volume builds up but the Pressure curve would rise way above the normal, not below the normal.

I think you mean Ventricle...
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I Think is Aortic Insuficiency.
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Quote:
Originally Posted by patelMD View Post
I think you mean Ventricle...
lol yes, not escape out *into* the aorta
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the dotted line is CONTROL LINE.
so answer is ----> MI
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Quote:
Originally Posted by IKR123 View Post
the dotted line is CONTROL LINE.
so answer is ----> MI


MI Looks like that...
Grey represents Control
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Old 06-21-2011
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By MI do you mean myocardial infarct? Thats def a possibility.... but only compensated MI would look like that -- since stroke volume is partly restored because of the compensation would increase the preload.

Last edited by step1saga; 06-21-2011 at 05:45 PM.
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Quote:
Originally Posted by step1saga View Post
By MI do you mean myocardial infarct? Thats def a possibility.... but only compensated MI would look like that -- since stroke volume is partly restored because of the compensation would increase the preload.
I think he means Mitral Insufficiency or Regurgitation.
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Old 06-21-2011
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Quote:
Originally Posted by IKR123 View Post
This dotted line is CONTROLLED LINE WHAT DOES BOLD LINE SHOWS in this picture below shows what kind of heart disease...

Attachment 1581
click image to enlarge

a) AS
b) MI
C) AI
d) MS
yup its AI , increased EDV and decreased pressure.
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  #20  
Old 11-16-2015
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Default Here is how to read it correctly

Here is how to read it:

First if the dotted line is the disease:

1- There is decreased preload
2- There is increased afterload
3- Stroke volume is decreased (ie, ejection fraction is decreased)
4- End Diastolic Volume and Pressure have decreased (because isovolumetric contraction line is shifted to the left)
5- End Systolic Volume and Pressure have decreased because isovolumetric relaxatio line is shifted to the left)
5- Both isovolumetric contraction and relaxation line have shifted to the left
6-Cardiac Contractility is increased and intraventricular systolic pressure is increased as well

Second if the bold line is the disease:

1- There is increased preload
2- There is decreased afterload
3- Stroke volume is increased (ie, ejection fraction is increased)
4- End Diastolic Volume and Pressure have increased (because isovolumetric contraction line is shifted to the right)
5- End Systolic Volume and Pressure have increased because isovolumetric relaxation line is shifted to the right)
6- Both isovolumetric contraction and relaxation line have shifted to the right
7-Cardiac Contractility is decreased and intraventricular systolic pressure is decreased as well


I think the person who originally posted this is confused about which line represents the disease and which line represents the normal.
But since in all books and on all questions banks, the dotted line is the disease so let's go with that and solve this mystery:

So it fits AS since in AS we expect all the following
1- There is decreased preload (less blood goes to systemic circulation and less blood comes back to heart because of stenosed aortic valve)
2- There is increased afterload (because of stenosed aortic valve)
3- Stroke volume is decreased (ie, ejection fraction is decreased) because of stenosed aortic valve
4- End Diastolic Volume and Pressure have decreased (because isovolumetric contraction line is shifted to the left)
5- End Systolic Volume and Pressure have decreased because isovolumetric relaxatio line is shifted to the left) this is the only one that does not go with AS
5- Both isovolumetric contraction and relaxation line have shifted to the left
6-Cardiac Contractility is increased and intraventricular systolic pressure is increased as well

Here is why the other answer choices are WRONG

in AR we expect
1- no change in afterload (because regurgitation is important when talking about diastole since during systole the aortic valve is supposed to be open anyway)
3- Stroke volume to be increased (because during diastole blood regurgitaates back to left ventricle) but here the dotted line shows stroke volume to be decreased so it is not AR
These two reasons are enough to say it is not AR

Also it is not MS because in MS left ventricular pressure and afterload are all near-normal.

It is not MR because in MR blood regurgitates during systole when the valve is supposed to be closed. This decreases stroke volume and will decrease preload eventually but should not affect cardiac contractility which is affected in the dotted line. So it is not MR.

But here is the GREAT NEWS; USMLE step 1 will never present a question so complicated like this. To be honest with you, I do not think this is a real question either but I went ahead and explained it anyway. On Step one they will give you enough info to lead you to the valvular heart disease to a point where you will not even need to look at this pressure-volume loop.
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  #21  
Old 11-16-2015
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Default Videos Explaining Pressure-Volume Loops

Here watch these videos on Pressure-Volume Loops

https://www.youtube.com/watch?v=RwWeDKevxlw
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