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| − | ==Passive congestion== | + | ==[[Liver Congestion, Passive]] == |
| − | Usually associated with right-sided heart failure because when the right side of the heart fails to function properly, blood will back up through the veins into the [[Liver - Anatomy & Physiology|liver]].
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| − | The appearances and changes in the [[Liver - Anatomy & Physiology|liver]] will depend on whether the conggestion is of short or long duration.
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| − | ===Acute congestion===
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| − | *occurs in acute right-sided heart failure and in shock
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| − | ====Gross====
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| − | *[[Liver - Anatomy & Physiology|liver]] is swollen and engorged with rounded edges to the lobes
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| − | *fibrin may be present on the surface, coming from the dilated subcapsular lymphatics
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| − | *blood oozes freely from the cut surface
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| − | *the sinusoids are dilated and packed with red blood cells
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| − | ====Microscopically====
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| − | *hepatic venules and sinusoids engorged with blood
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| − | ===Chronic congestion===
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| − | *occurs in chronic right-sided heart following on from left-sided heart failure eg endocardiosis in dogs, cardiomyopathy in cats [need link in future]
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| − | ====Gross====
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| − | *slightly swollen with rounded edges
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| − | *capsular surface may be paler and thicker than normal
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| − | *alternating red and yellow areas on the cut surface: accentuates the acinar pattern
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| − | **this contrasting red and yellow mottled gross appearance (especially that of the formalin-fixed specimen) resembles the cut surface of a nutmeg, and is referred to as ''''nutmeg'''' [[Liver - Anatomy & Physiology|liver]]
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| − | **at this stage the [[Liver - Anatomy & Physiology|liver]] may have returned to normal size or be slightly smaller than normal
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| − | *fibrosis can develop in the congested centrilobular zones and the liver becomes firm to section, ie cardiac fibrosis
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| − | ====Microscopically====
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| − | *the red areas are engorged and dilated hepatic venules which may show a substantial increase in perivenular fibrous tissue due to atrophy and loss of adjacent hepatocytes
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| − | *the yellowish areas are the midzonal and perhaps periportal hepatocytes in very long standing cases which have undegone fatty change due to hypoxia and malnutrition
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| − | *the Kuppfer cells may contain considerable haemosiderin pigment
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| − | **golden brown in H&E sections
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| − | **blue with Perls' Prussian blue stain (specific for haemosiderin)
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| | ==Thrombosis== | | ==Thrombosis== |