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Old 09-08-2011
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Heart Cyanosis in Right heart failure

Goljan says that cyanosis occurs particularly in right heart failure because there is increased time for peripheral tissues to extract oxygen which leads to a decreased oxygen saturation. Isn't that a paradox? I mean even if there is increased extraction of oxygen in the tissues and saturation in the venous system goes down, won't gas exchange in the lungs equilibrate it back to alveolar oxygen levels? I don't understand what I'm missing there. Can someone please explain? Its in page 164 in the 3rd edition of Rapid Review Pathology.
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Old 09-08-2011
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Right heart failure - so the right ventricle fails to pump deoxygenated blood to the lungs - the flow goes down, - more time to extract oxygen - so venous blood has lots of CO2 and super low O2 content- because right heart does not pump this venous blood well it must accumulate somewhere - like in the small venules.

This is what I think...
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Originally Posted by DocSikorski View Post
Right heart failure - so the right ventricle fails to pump deoxygenated blood to the lungs - the flow goes down, - more time to extract oxygen - so venous blood has lots of CO2 and super low O2 content- because right heart does not pump this venous blood well it must accumulate somewhere - like in the small venules.

This is what I think...
But what about the oxygenation of blood in the lungs that then goes to the left ventricle and from there to the tissues. Won't that be normal? What I understand is that because of backup of blood from the right side into the venous system, blood flow slows down and so tissues extract more oxygen from the slow flowing blood and hence decreasing the mixed venous oxygen content. But it should affect arteial oxygen right? How does it cause cyanosis?
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Old 09-08-2011
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Originally Posted by infinity89r View Post
But what about the oxygenation of blood in the lungs that then goes to the left ventricle and from there to the tissues. Won't that be normal? What I understand is that because of backup of blood from the right side into the venous system, blood flow slows down and so tissues extract more oxygen from the slow flowing blood and hence decreasing the mixed venous oxygen content. But it should affect arteial oxygen right? How does it cause cyanosis?
Its simple don't over think it my friend just know this: blood flow to lungs decrease hence increase in CO2 n cyanosis, that's enough to know of course plus the other symptoms (nutmeg liver and pitting edema)
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