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  #1  
Old 02-24-2012
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Default Ejection Time Cardio

I have 2 questions about Pg. 307 FA 2012.

What does Ejection Time mean here?
Do Nitrates decrease ET because of decrease preload/EDV and vice versa for B-blocks?

Also for B-blockers it says decrease BP...
For non-specific B-blockade a drop in HR would have to cause peripheral vasoconstriction because BP drops (Carotid Sinus reflex via alpha-1 stimulation) and thus an increase in TPR and BP.

But I also realize B-blockade decreases renin release. So does this trump the vasoconstriction reflex and thats why its an overall decrease in BP?

Thanks!
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  #2  
Old 02-25-2012
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Anyone... bump.
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Old 02-25-2012
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Quote:
Originally Posted by No_BS View Post
I have 2 questions about Pg. 307 FA 2012.

What does Ejection Time mean here?
Do Nitrates decrease ET because of decrease preload/EDV and vice versa for B-blocks?

Also for B-blockers it says decrease BP...
For non-specific B-blockade a drop in HR would have to cause peripheral vasoconstriction because BP drops (Carotid Sinus reflex via alpha-1 stimulation) and thus an increase in TPR and BP.

But I also realize B-blockade decreases renin release. So does this trump the vasoconstriction reflex and thats why its an overall decrease in BP?

Thanks!
ejection time is the time taken to eject the blood from the ventricle so here if you decrease the preload you decrease the volume in the ventricle so , the less amount of blood is easily ejected faster so less ejection time .. now b blockers increase afterload by blocking B2 receptor so ejection against more force needs more time ...

b blockers decrease heart rate and renin release so they will decrease BP , i know you might think that B2 blockade leads to vasoconstriction ... but no .. its AT 2 that causes the main vasoconstriction , thus dec renin manages it ...

hope this helps
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Old 02-25-2012
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Quote:
Originally Posted by Hitman View Post
ejection time is the time taken to eject the blood from the ventricle so here if you decrease the preload you decrease the volume in the ventricle so , the less amount of blood is easily ejected faster so less ejection time .. now b blockers increase afterload by blocking B2 receptor so ejection against more force needs more time ...

b blockers decrease heart rate and renin release so they will decrease BP , i know you might think that B2 blockade leads to vasoconstriction ... but no .. its AT 2 that causes the main vasoconstriction , thus dec renin manages it ...

hope this helps
BB- Decrease Afterload and increase preload, not vice versa.
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Old 02-25-2012
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Originally Posted by stepstar View Post
BB- Decrease Afterload and increase preload, not vice versa.
well that is what i said .......

b blockers decrease heart rate and renin release so they will decrease BP , i know you might think that B2 blockade leads to vasoconstriction ... but no .. its AT 2 that causes the main vasoconstriction , thus dec renin manages it ...

so its clear , it decreases afterload , i just wanted to say loss of B2 stimulation in nonselective block may lead you to think that vasoconstriction will occur but decrease in renin doesnot let it happen .... decrease HR allows greater filling time and increases CO
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Old 02-25-2012
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I think stepstar meant this part.

Quote:
Originally Posted by Hitman View Post
now b blockers increase afterload by blocking B2 receptor so ejection against more force needs more time ...
but I know you that since the second part of the post explains this effect perfectly, thanks Hitman!
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Old 05-01-2014
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great!
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