Sep 11, 2015
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Medical Student
I recently had a question in a Cardiac Physiology exam that left me scratching my head:
the question was, as best I can recall:

The absence of (or extreme decrease in) Reactive Hyperemia would be most indicative of what condition?

a. Atherosclerosis
b. CHF
(and the other two questions were obviously wrong)

I put CHF, because although I know that advanced atherosclerosis could cause a decrease in reactive hyperemia, my thinking was this: If I saw a clinical presentation of the complete absence of reactive hyperemia (which would essentially be pitting edema? correct me if I'm wrong) this would necessitate the need to rule out something like heart failure. I brought this up with my professor, and he shot this down immediately, saying that pitting edema alone would not immediately indicate CHF. Fair enough, I thought, but couldn't we say the same about atherosclerosis? My reasoning for my answer was based on the idea that clinically we should always rule out the worse possible scenario..maybe someone can enlighten me, is the lack of reactive hyperemia not associated with heart failure?

Thanks!
 

Instatewaiter

But... there's a troponin
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Apr 28, 2006
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Attending Physician
I recently had a question in a Cardiac Physiology exam that left me scratching my head:
the question was, as best I can recall:

The absence of (or extreme decrease in) Reactive Hyperemia would be most indicative of what condition?

a. Atherosclerosis
b. CHF
(and the other two questions were obviously wrong)

I put CHF, because although I know that advanced atherosclerosis could cause a decrease in reactive hyperemia, my thinking was this: If I saw a clinical presentation of the complete absence of reactive hyperemia (which would essentially be pitting edema? correct me if I'm wrong) this would necessitate the need to rule out something like heart failure. I brought this up with my professor, and he shot this down immediately, saying that pitting edema alone would not immediately indicate CHF. Fair enough, I thought, but couldn't we say the same about atherosclerosis? My reasoning for my answer was based on the idea that clinically we should always rule out the worse possible scenario..maybe someone can enlighten me, is the lack of reactive hyperemia not associated with heart failure?

Thanks!
Reactive hyperemia is the increase in blood flow following ischemia, it is tied to endothelial function and is in part a measure of flow reserve. It has nothing to do with heart failure or edema (unless you all define it differently). In CAD, your arteries maximally dilate already so there is limited/reduced reactive hyperemia, almost by definition. This is how we use vasodilators to indicate ischemia in nuclear stress testing- the areas of flow limiting stenoses are already maximally dilated and have no flow reserve. The coronary endothelial function is largely unaffected in chf which is why our nuclear stress testing shows normal perfusion in Nonischemic cardiomyopathies.