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36 Cards in this Set
- Front
- Back
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where may the effects of an arterial thrombosis occur?
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immediate service area or distant tissues
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what is the effect of an arterial thrombosis in the immediate service area?
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no problem if collateral circulation is intact, but infarction if collateral circulation is inadequate
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what is the effect of an arterial thrombosis in the distant tissues?
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embolism; detached intravascular undissolved material carried to distant site
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how do arterial thrombosis affect distant tissues?
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plug vasculature at the next narrow place which can lead to infarction in either the venous (lungs) or arterial (systemic circulation)
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what is the name for an aortic bifurcation thrombus?
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saddle thrombus
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what is a saddle thrombus?
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an aortic bifurcation embolism
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what is a thromboemboli?
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an emboli that includes thrombi (more common) and contain worms, fragments, bacterial clumps, air, fat, tumor thrombosis (metastasis), bone or fibrocartilage, or foreign body
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what are the consequences of thromboemboli?
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metastasis, infarction, acute circulatory failure, abscess from septic embolus, arterial aneurysm
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what occurs with metastasis due to thromboemboli?
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dissemination of infection/neoplasm
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what occurs with infaction due to thromboemboli?
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inadequate collateral or compromised collateral supply compromised
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what occurs with acute circulatory failure due to thromboemboli?
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thromboemboli impact R heart or pulmonary trunk
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what occurs with abscess from septic embolus due to thromboemboli?
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infarction, inflammation, liquefaction
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what occurs with arterial aneurysm due to thromboemboli?
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dilation, arterial wall weakened by thrombosis, arteritis
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what is the most common example of an arterial aneurysm?
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verminous arteritis of the cranial mesenteric artery in the horse due to migrating larvae of Strongylus vulgaris
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what occurs when an aneurysm ruptures?
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usually leads to rapid fatal hemorrhage
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what can be used to categorize the fate of thrombi?
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small, medium, large
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what is the fate of small thrombi?
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dissolved by fibronolysis via plasminogen activator-plasmin system
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what is the fate of medium thrombi?
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organized and incorporated into vessel wall; the marginal endothelium grows over thrombotic mass creating endothelial continuity or new capillary formation into incorporated portion
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what is the fate of large thrombi?
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organized and recanalized when fibrovascular tissue and MP's invade thrombus; shrinkage from contraction of myofibroblasts result in recanalization (flow) and some incorporation into wall, some recanalization of center of thrombus
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what eventually occurs with thrombus?
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recedes into vessel wall (scars) otherwise it clots causing emboli
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where can embolization occur?
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arterial or venous
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define infarct
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a localized area of ischemic necrosis in an organ or tissue resulting from the occulusion of either its arterial supply or venous drainage
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what are the causes of an infarct?
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thrombosis/thromboemboli, arterial spasm, external occulsion of vessel, narrowing of arterial lumen
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what is the most common cause of an infarct?
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thrombosis/thromboemboli
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what causese narrowing of arterial lumen in infarcts?
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lesion on walls (arteriosclerosis)
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what causese arterial spasm in infarcts?
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poisoning by ergot
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what causese external occlusions of vessels?
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ligation, external pressure, strangulation due to volvulus
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what vessels tend to infarct due to external occlusions?
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veins
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how are infarcts classified?
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color, presence/absence of contamination bacteria, morphology
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describe white infarcts?
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arterial occulsions in solid tissues/organs with little/no collateral circulation (heart, kidney) which have single vascular supply circuit, generally older infarcts
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describe red infarcts?
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following venous occulsion; in loose tissue where seepage from peripheral hemorrhage is possible; dual vascular supply (lungs, small intestine), younger infarcts
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describe septic infarcts?
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contaminated with bacteria; coagulation to liquefaction to abscess
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what is the general gross morphology of infarcts?
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wedge shaped on cut surface with apex of wedge points toward focus of occlusion
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what is the gross morphology of white infarcts?
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yellow-white, sharply demarcated afte a few days
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what occurs over time with infarcts?
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margins becme better defined; peripheral hyperemia resulting in inflammation
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what is the histology of infarcts?
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coagulation necrosis, marked hemorrhage in red infarcts; necrotic focus replaced by scar tissue but may have some regeneration at periphery
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