SDK
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What is the effect of aortic stenosis on preload????
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| gchomicz
Forum Newbie
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preload is either decreased d/t back flow/stasis....or, my 2nd choice ans. would be no change.
which one?
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| msduncan
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I think it's actually increased. Afterload sure is increased, because the aortic stenosis makes it difficult for the blood to exit the left ventricle. However, preload is related to end-diastolic volume. Since in aortic stenosis less blood exits the left ventricle, blood accumulates in the LV during diastole, increasing end-diastolic volume, thus increasing the preload.
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| Zat
Forum Senior
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I agree with msduncan.
I think it would have to increase. I put it this way.... the indices of Preload are End-diastolic volume, End-diastolic Pressure,....
Wouldn't those increase with Aortic Stenosis? But........
After development of Concentric hypertrophy of the LV, the LV would be able to develop enough pressure to pump the needed stroke volume against the Afterload.
Another point is that if Preload did increase with Aortic Stenosis, there would be back-pressure on the Pulmonary system and the development of Pulmonary Edema.....??
Does anyone have a clear explanation for this?
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| ssrpk
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agree with u zat! i don't think there's a clear cut orrelation b/w pre-load and aortic stenosis, it could sway in either directioin!
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| Zat
Forum Senior
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I think i found a clear answer to the question with this pressure-volume loop....
According to the loop, the EDV increases, there Preload does increase.
Although ESV also increases even more, the end product of Stroke Volume is therefore decreased.
It's also clear from the loop that the Afterload is greatly increased, no doubt about that.
Please note that these are the acute changes as the diagram mentions. Contractility (Inotropy) hasn't changed to partially compensate for the increased Preload yet, nor have any other compensatory mechanisms such as Heart Rate. Eventually these compansatory mechanisms will kick in to restore Stroke Volume and therefore Cardiac Output.
Hope the diagram helps.....
Attached Files:
aortic_stenosis_PV_loop.gif (8 KB, 11 downloads)
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