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Old 06-27-2011
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Stethoscope Audible murmurs and Valsalva maneuver

hi
Uworld says, that with valsalva manuevre and standing(i.e conditions reducing venous return), the murmurs of MVP and hypertrophic cardiomyopathy becomes MORE audible ....??can anyone explain why?
what i thought was decrease in venous return would decrease the blood flowing through the left heart and so the systolic murmur of MVP would DECREASE as most of the blood will through the aorta and not back into LA...
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Old 06-28-2011
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In hypertrophic cardiomyopathy, a decrease in left ventricular outflow size is associated with an increase in the intensity of the ejection systolic murmur. Remember that this patients have a dynamic outflow obstruction, usually due to systolic anterior motion (SAM) of the anterior leaflet of the mitral valve.

So, with a valsalva maneuver -> decreases preload -> decreased filling of the left ventricle -> increase in LVOT obstruction.
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Old 06-28-2011
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thanx....and

Also why would a murmur of MVP INCREASE with reduction in the preload...shouldnt it decrease as a decrease in LVEDV would also decrease the CO in general i.e. less amount of blood will regurgitate back into LA during systole thereby reducing the murmur...
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Old 06-28-2011
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Quote:
Originally Posted by drnirajmavani View Post
thanx....and

Also why would a murmur of MVP INCREASE with reduction in the preload...shouldnt it decrease as a decrease in LVEDV would also decrease the CO in general i.e. less amount of blood will regurgitate back into LA during systole thereby reducing the murmur...

When there is deceased preload,LVEDV will be decreased..so the leaflets of mitral valve which are prolapsed will not be apposed to each other ,so they will be flapping..thats why there is increased intensity of the murmur..
On the other hand,when the preload is increased,the LVEDV will be increased and the valve leaflets will be opposed to each other closing the prolapsedue to increase pressure in the LV,the murmur will decrease ,because they wont get a space to flap and allow the blood to move in the Atrium..
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Old 06-28-2011
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Quote:
Originally Posted by drnirajmavani View Post
thanx....and

Also why would a murmur of MVP INCREASE with reduction in the preload...shouldnt it decrease as a decrease in LVEDV would also decrease the CO in general i.e. less amount of blood will regurgitate back into LA during systole thereby reducing the murmur...
This is because the maneuvers which decrease the volume of the left ventricle (Valsalva, standing) will cause the prolapse to occur sooner and more severely. Those that increase venous return and diastolic filling (squatting) -> enhance the ventricular volume -> help to maintain tension along the chordae-> keep the valve shut.
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Old 06-28-2011
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For a visual :

http://my.clevelandclinic.org/heart/...m/default.aspx

There is a nice comparison photo if you scroll down.

To clarify, I always thought that the increased blood in the Left Ventricle made it more difficult for the mitral leaflet to cause a blockage against the ventricular septum? So with more filling, there is more space and therefore a less obstructed outflow tract, but with less filling, the mitral valve leaflet is closer to the ventricular septum and therefore causes a greater obstruction? Do i have this all wrong? Thanks!
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Old 06-28-2011
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Quote:
Originally Posted by spaidak2 View Post
For a visual :

http://my.clevelandclinic.org/heart/...m/default.aspx

There is a nice comparison photo if you scroll down.

To clarify, I always thought that the increased blood in the Left Ventricle made it more difficult for the mitral leaflet to cause a blockage against the ventricular septum? So with more filling, there is more space and therefore a less obstructed outflow tract, but with less filling, the mitral valve leaflet is closer to the ventricular septum and therefore causes a greater obstruction? Do i have this all wrong? Thanks!
you are correct.
more preload -> less dynamic outflow obstruction
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