LVED Pressure and Volume in Systolic and Diastolic Heart Failure! - USMLE Forums
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  #1  
Old 01-24-2012
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Heart LVED Pressure and Volume in Systolic and Diastolic Heart Failure!

Uworld says....

In diastolic heart failure only LVEDp increases and in systolic heart failure LVEDp and LvEDV both increase cany anyone explain???
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Old 01-25-2012
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In diastolic heart failure only LVEDp increases
DIASTOLIC heart failure=== heart cannot relax properly.. hence it cannot FILL.. hence volume cannot increase.. and there is only an increase in pressure..

(imagine a hypertrophied.. empty heart pumping.. n trying to pump out more blood when there is none to pump out cos it cannot relax enough to fill it)

eg-- concentric hypertrophy of the heart.


Quote:
systolic heart failure LVEDp and LvEDV both increase
SYSTOLIC failure=== heart cannot pump out properly.. hence blood gets left behind... so for the next cycle of contraction.. it will be the NEW blood from the atria+ the old left behind blood.... hence resulting in INCREASED VOLUME...

n obviously due to increased VOlume.. the heart tries to increase the pressure to pump out the INCREASED/EXcESSIVE volume

hence increase in LVEDP and LVEDV

hope that helps
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Old 01-25-2012
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ok that is right but also in UWOrld it says that in diastolic dysfuction there is increase in LVEDP , that is ok so as to keep normal CO and stroke volume , but it says that LVEDV is NORMAL in diastolic dysfunction as the increase in LVEDP corrected it , how is that ????
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Old 01-25-2012
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that is how INCREASE LVEDP can nrmalize LVEDV which is decreased due to decrease compliance???? as I know LVEDP can increase CO and STROKE VOLUME but not LVEDV???
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Old 01-25-2012
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Originally Posted by rose View Post
ok that is right but also in UWOrld it says that in diastolic dysfuction there is increase in LVEDP , that is ok so as to keep normal CO and stroke volume
probably cos the heart is pumping with more force.. and hence emptying more completely (initially) when the LVEDV is normal....

but eventually the continuous high pressure leads to hypertrophy of the muscles and
decrease in the actual ventricular cavity volume.. hence causing decreased LVEDV.

atleast thats my understanding of it.. its a gradual process...
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Old 01-25-2012
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Originally Posted by mbbs2010 View Post
probably cos the heart is pumping with more force.. and hence emptying more completely (initially) when the LVEDV is normal....

but eventually the continuous high pressure leads to hypertrophy of the muscles and
decrease in the actual ventricular cavity volume.. hence causing decreased LVEDV.

atleast thats my understanding of it.. its a gradual process...
yes that is what I understand too and agree totally , but Uworld says another thing increase LVEDP lead to increase LVEDV , why??
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Old 01-25-2012
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Originally Posted by rose View Post
yes that is what I understand too and agree totally , but Uworld says another thing increase LVEDP lead to increase LVEDV , why??

no idea!! lol...

give me the question ID if u can look it up. will check up on my uworld n see if i can help the both of us n everyone here
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Originally Posted by mbbs2010 View Post
no idea!! lol...

give me the question ID if u can look it up. will check up on my uworld n see if i can help the both of us n everyone here
its 186 , u have to read all the explanation
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Old 01-25-2012
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well , I got the Qs its in pathophysiology ID no 186 ( 378969 )

well let me try too , i guess we all agree that volume and pressure ratio is called compliance = dv/dp , now we know that in diastolic dysfunction there is decrease in compliance due to hypertrophy thus decrease in volume (dv) now if you shift the formulae to find dv = compliance (that has decreased )* dv

so from (decreased due to hypertrophy) dv = (decreased compliance) * dp ..... its clear that the only way you can increase dv back to normal is by increasing dp ....... that is why LVEDP increases and can bring the LVEDV to only normal ......

hope this helps ........
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Originally Posted by rose View Post
its 186 , u have to read all the explanation

ok read it.. in this case..

if you are talking practically in the body ------what they are equating LVEDV with Cardiac output. and using it as a synonym.. hence trying to say that to compensate for decreased CO and SV.. the LVEDP must increase substantially to normalize CO and SV..

they hv just used CO and LVEDV interchangeably.. it is confusing the way it is worded in the end... but if you look at the explanation right below the diagram. its very clear..
dont get worked up by it.



or it may be a graphical and theoretical ------change of bringing the graph of LVEDV to normal that they are referring to as explained by hitman above..
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Originally Posted by mbbs2010 View Post
ok read it.. in this case..

if you are talking practically in the body ------what they are equating LVEDV with Cardiac output. and using it as a synonym.. hence trying to say that to compensate for decreased CO and SV.. the LVEDP must increase substantially to normalize CO and SV..
yes , i think it is either the way done by the above equation or it is that we need to understand that in diastole as heart gets filled up the pressure in the ventricle keeps on increasing as the volume of blood gets filled in it with the loss of volume the heart pumps out all the blood in the ventricle leading to decrease in LVEDV ... now LVEDV has decrease foe eg from 25 normally 10 ml but so has the CO and SV now to increase CO we need the ventricle to be filled with more blood , which needs more pressure to expand , thus by increasing LVEDP we increase the volume of blood in ventricle and so more blood is pumped out ie CO and more blood is left behind that is LVEDV which both come back to normal .....

this is all i can get off it .....
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Old 01-26-2012
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Originally Posted by Hitman View Post
yes , i think it is either the way done by the above equation or it is that we need to understand that in diastole as heart gets filled up the pressure in the ventricle keeps on increasing as the volume of blood gets filled in it with the loss of volume the heart pumps out all the blood in the ventricle leading to decrease in LVEDV ... now LVEDV has decrease foe eg from 25 normally 10 ml but so has the CO and SV now to increase CO we need the ventricle to be filled with more blood , which needs more pressure to expand , thus by increasing LVEDP we increase the volume of blood in ventricle and so more blood is pumped out ie CO and more blood is left behind that is LVEDV which both come back to normal .....

this is all i can get off it .....
yes that is the only explanation BUT originally the reason for diastolic dysfunction (which is stiffness or hypertrophy) was not removed and it is still there , but anyway that is the only possible explanation
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Old 07-14-2014
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This is how I figured it out.

So Systolic HF = dilated cardiomyopathy secondary to contractilily failure, Diastolic HF= hypertrophic CM, secondary to an increase in afterload ( HTN, infiltrative diseases).

what happens in SHF w/ LVEDP:
decrease in contractility => increase in End Diastolic volume => blood builds up increasing the End systolic volume = > causing an INCREASE in LVEDP (there's more volume that is left in the ventricle, since it's not contracting properly)

What happens in DHF w/ LVEDP:
hypertrophy => Decrease in VOLUME (since now the ventricles are thicker) however PRESSURE BUILDS UP since now the volume of blood didn't change but there's less space for that blood to fill up => increasing ventricular wall tension => increasing LVEDP ( a stiff ventricle trying to fill up)


EF difference :

SHF=> EF = SV/EDV. in systolic HF, the EDV is increased!!! REMEMBER VENTRICLES ARE NOT ABLE TO CONTRACT PROPERLY. An increase in the denominator => low EF.


DHF=> EF = SV/EDV. in this situation BOTH SV and EDV are decreased => b/c
-SV: is decreased since EDV= preload, and bc of Frank Starling's, a decrease in preload = a decrease in SV or CO

-EDV: is decreased since ventricles are hypertrophied (decreasing the physical space for the volume to be contained in)

however there's an INCREASE IN LVED PRESSURE!! and a DECREASE in VOLUME

SINCE BOTH SV AND EDV ARE DECREASED EF IS PRESERVED in DHF.

I hope this images helps w/ the explanation.
Attached Thumbnails
LVED Pressure and Volume in Systolic and Diastolic Heart Failure!-20140714_185304.jpg   LVED Pressure and Volume in Systolic and Diastolic Heart Failure!-20140714_184052.jpg  
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