Why are pulmonary infarctions more likely to be hemorrhagic...?

[ratatat]

Hi. Does anyone know the answer to this question? I figure it has something to do with the double blood supply, but I can't figure it out. It's been burning inside of me.

Thanks a billion.

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[cpants]

Hi. Does anyone know the answer to this question? I figure it has something to do with the double blood supply, but I can't figure it out. It's been burning inside of me.

Thanks a billion.

Yeah, you are on the right track. Basically, most infarcts are from a PE blocking the pulmunary arterial blood supply. You still have blood to the area from aorta (bronchial arteries), but it isn't enough to sustain the tissue. Thus, you infarct, but there is still blood in the tissue.

 

[Raryn]

I'm thought it was simply because the lungs aren't a solid organ.

Coagulation necrosis when there's no open space, hemorrhagic necrosis when there's plenty, liquefactive necrosis in the brain.

 

[cpants]

I'm thought it was simply because the lungs aren't a solid organ.

Coagulation necrosis when there's no open space, hemorrhagic necrosis when there's plenty, liquefactive necrosis in the brain.

Nah, I think it is the dual blood supply. You get hemorrhagic necrosis in the liver also for the same reason. When there is an arterial blockage in an organ with one blood supply, there is no blood distal to the blockage, therefore impossible to get hemorrhagic infarct. In the case of the lung (pulmonary/bronchial) and the liver (portal/systemic) there is still some blood supply to the tissue, just not enough to sustain it.

 

[Raryn]

Nah, I think it is the dual blood supply. You get hemorrhagic necrosis in the liver also for the same reason. When there is an arterial blockage in an organ with one blood supply, there is no blood distal to the blockage, therefore impossible to get hemorrhagic infarct. In the case of the lung (pulmonary/bronchial) and the liver (portal/systemic) there is still some blood supply to the tissue, just not enough to sustain it.

Are you sure about that? Goljan very clearly says (pg 18) that the reason for Hemmorhagic infarcts is "Loose-textured tissue (e.g., lungs, small bowel) allows RBCs to diffuse through necrotic tissue"

The previous page says for pale/ischemic infarcts "Increased density of tissue (e.g., heart, kidney, spleen) prevents RBCs from diffusing through necrotic tissue"

I remember that liver infarcts are pretty much unheard of because of the dual blood supply, but I'm also pretty sure it would be a pale infarct, not a hemorrhagic one. From the tissue density if nothing else.

 

[RoadRunner17]

I remember the pathologist in one of our lectures stating the dual blood supply as the reason why lungs tend to have the hemorrhagic type of infarct. I can't really argue with Goljan but just relaying what the pathologist told us. I'd go with that, but I really don't consider it that huge of a deal.

 

[cpants]

Had to bust out the Robbins (Page 100, Basic Pathology, 8th Ed.):

Red infarcts occur (1) with venous occlusions (such as in ovarian torsion; (2) in loose tissues (such as lung) that allow blood to collect in the infarcted zone; (3) in tissues with dual circulations such as the lung and small intestine, permitting flow of blood from an unobstructed parallel supply into a necrotic area (such perfusion not being sufficient to rescue the ischemic tissues); (4) in tissues that were previously congested because of sluggish venous outflow; (5) when flow is re-established to a site of previous arterial occlusion and necrosis (e.g., fragmentation of an occlusive embolus or angioplasty of a thrombotic lesion).

Hope this answers your question.

 

[loudentl]

I think Raryn is correct. The tissue consistency/texture is one of the main reasons as to why hemorrhagic infarcts are more common in the lungs. Which would also explain why the liver which also has a dual blood supply actually has pale infarcts more commonly than hemorrhagic. Robbins also explains this well and actually has it listed as a more significant factor at number 2 versus the number 3 cause which discussed the dual blood supply. I did however get my notes from Goljan audio as well.