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.

The appearances and changes in the liver will depend on whether the conggestion is of short or long duration.

Acute congestion

• occurs in acute right-sided heart failure and in shock

Gross

• liver is swollen and engorged with rounded edges to the lobes
• fibrin may be present on the surface, coming from the dilated subcapsular lymphatics
• blood oozes freely from the cut surface
• the sinusoids are dilated and packed with red blood cells

Microscopically

• hepatic venules and sinusoids engorged with blood

Chronic congestion

• occurs in chronic right-sided heart following on from left-sided heart failure eg endocardiosis in dogs, cardiomyopathy in cats [need link in future]

Gross

• slightly swollen with rounded edges
• capsular surface may be paler and thicker than normal
• alternating red and yellow areas on the cut surface: accentuates the acinar pattern
  • 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
  • at this stage the liver may have returned to normal size or be slightly smaller than normal
• fibrosis can develop in the congested centrilobular zones and the liver becomes firm to section, ie cardiac fibrosis

Microscopically

• 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
• 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
• the Kuppfer cells may contain considerable haemosiderin pigment
  • golden brown in H&E sections
  • blue with Perls' Prussian blue stain (specific for haemosiderin)