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  #1  
Old 06-08-2012
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Heart Cardiac Function Curves Practice



I think i got this all straightened out in my head, so i thought we could all exercise ourselves a bit regarding this concept

What are the scenarios for the different letters?
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  #2  
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The middle one, is normal.

H point, is heart failure with increased preload (due to compensation i.e. activation of Renin-angiotensin system, and increased sympathetic tone)

G point, is heart failure with no increase in preload (no compensation)

Anyone have any examples on the other points?

Last edited by Renaissance; 06-08-2012 at 01:49 AM.
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Points D and E along the cardiac function curve indicate that contractility is the same along that line. So point D: Decreased vascular volume (Eg: haemorrhage), and point E: Increased Vascular volume (Blood transfusion.) Looked up Kaplan for this!
Don't know about the rest. Could B be Digoxin?
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I don't think B is digoxin, because -sure digoxin increases contractility but in an already failing heart. So the overall would still be decreased contractility (normal at best but definitely not increased).
opened up sturling curve, from first aid, page 255 lol

point E and hypervolemia (blood transfusion) makes sense.


point D and hypovolemia (hemorrhage) makes sense as well.

Last edited by Renaissance; 06-08-2012 at 05:05 AM.
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i think point G is narcotic overdose (decreased contractility with no change in volume).
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G- MI,
F- Shock
C- AV shunt, Fistula...
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Quote:
Originally Posted by one_destiny View Post
G- MI,
F- Shock
C- AV shunt, Fistula...
shock as in septic or anaphylactic shock? cardiogenic shock?
in shock you get decreased volume due to massive systemic venodilation (pooling of the blood) but isn't it supposed to be normal contractility?

and why does AV shunt/fistula have increased contractility?

Last edited by Renaissance; 06-08-2012 at 05:48 AM.
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Cardiogenic/Hypovolaemic
Because in that CO decreases and TPR increases as on that point..

And AV shunt at point C because for the same reason but ofcourse inverse relations,
CO increases and TPR decreases..
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Quote:
Originally Posted by Renaissance View Post
shock as in septic or anaphylactic shock? cardiogenic shock?
and why?

and why is AV shunt at point c? why is there an increased contractility?

I think F is cardiogenic shock. thr is reduced contractility (pump failure) and decreased CO as well as venous return.

Point C is AV fistula because u have a fistula which directs blood from the arteriole to the venule without going through the capillaries so that increases the preload. when u increase the preload, the heart will try to pump out the excess blood by increasing the contractility hence increasing the cardiac output.
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yea f is cardiogenic shock, finally making sense to me.

but im wondering if septic shock and anaphylactic shock are also c, i dont remember they have any change in contractility so they cant be the same as cardiogenic shock

Last edited by Renaissance; 06-08-2012 at 06:06 AM.
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Quote:
Originally Posted by Renaissance View Post
yea f is cardiogenic shock, finally making sense to me.

but im wondering if septic shock and anaphylactic shock are also c, i dont remember they have any decreased contractility so they cant be the same as cardiogenic shock
anaphylactic shock is probably A as there is widespread vasodilation, so decrease in TPR.
But idk, this is getting confusing. better check it out somewhere to be sure
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There are two lines on the curve.
Solid lines are showing CO.
Dotted lines are showing RA Pressure.
In the above diagram, normal is where the two lines in the middle intersect.

First look at CO - if the solid line is shifted to the left = increased contractility. If the solid line is shifted to the right = decreased contractility.
(Also, know that TPR has a reflex change opposite to HR, so when there is increased HR (contractility), the TPR would decrease and vice versa)

Next look at RAP - if the dotted line is shifted above = increased blood volume. If the dotted line is shifted down = decreased blood volume.

I think that's right. Correct me if I'm wrong!

Once you have these concepts down, its pretty straight forward from there. Don't have to memorize anything, its just plug n play concepts.
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Quote:
Originally Posted by Hope2Pass View Post
There are two lines on the curve.
Solid lines are showing CO.
Dotted lines are showing RA Pressure.
In the above diagram, normal is where the two lines in the middle intersect.

First look at CO - if the solid line is shifted to the left = increased contractility. If the solid line is shifted to the right = decreased contractility.
(Also, know that TPR has a reflex change opposite to HR, so when there is increased HR (contractility), the TPR would decrease and vice versa)

Next look at RAP - if the dotted line is shifted above = increased blood volume. If the dotted line is shifted down = decreased blood volume.

I think that's right. Correct me if I'm wrong!

Once you have these concepts down, its pretty straight forward from there. Don't have to memorize anything, its just plug n play concepts.
yes ur making perfect sense!
But the questions asking us to apply this concept can be a bit confusing!

Which letter would you say corresponds to anaphylactic/septic shock?
it's either A or D or F, but i cant figure out which one!
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Quote:
Originally Posted by Renaissance View Post
yes ur making perfect sense!
But the questions asking us to apply this concept can be a bit confusing!

Which letter would you say corresponds to anaphylactic/septic shock?
it's either A or D or F, but i cant figure out which one!
I think it would be A.

Anaphylactic/septic shock = vasodilation (decreased TPR), hypotension (low BV in part due to excessive vasodilation), low CO despite tachychardia (Increased contractility)

The CO at point A is 5 despite increased contractility. The venous return has decreased due to vasodilation/hypotension/low blood volume. And the MSFP has decreased by 2 as well.

Right? OR did I just make all this up? lol
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To be accurate, some of the scenrios you guys are coming up for these curves with will have two answers, one immediate and one compensatory.
In hemmorage and anaphylatic shock, the first/immediate response will be towards D, then with compensation (increased hr/contractility) it may go to A.
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How about B? There's an increase in contractility, while venous return is the same. Could it be Dobutamine? Which has predominantly a B-1 effect (Increased contractility, CO)? Or perhaps, moderate dose Epinephrine?
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Quote:
Originally Posted by dockhi View Post
How about B? There's an increase in contractility, while venous return is the same. Could it be Dobutamine? Which has predominantly a B-1 effect (Increased contractility, CO)? Or perhaps, moderate dose Epinephrine?
yes, i think point B is positive inotropy.
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This was also discussed here
Cardiac Output - Venous Return Curves

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