Circulatory disorders of liver

1. Anatomy Refresher

• Liver has a dual blood supply:
  • Portal vein (deoxygenated, from GI tract)
  • Hepatic artery (oxygenated)
• Both drain into sinusoids → central vein → hepatic vein → IVC.
• 3 categories of circulatory disorders:
  1. Impaired blood flow INTO the liver
  2. Impaired intrahepatic flow
  3. Hepatic vein OUTFLOW obstruction

2. Impaired Blood Flow INTO the Liver

A) Hepatic artery inflow

• Liver infarcts are rare (dual blood supply).
• HA thrombosis in a transplanted liver → graft loss.
• Localized parenchymal infarct → thrombosis / compression of intrahepatic artery branch by polyarteritis nodosa, embolism, neoplasia, sepsis.

B) Portal vein obstruction / thrombosis

• Produces signs of portal hypertension: abdominal pain, ascites, splenomegaly, esophageal varices (rupture-prone).
• Acute occlusion of visceral inflow → congestion → bowel infarction.
• Extrahepatic causes:
  • Peritoneal sepsis
  • Pancreatitis → splenic vein thrombosis → propagation to portal vein
  • Tumor
• Intrahepatic portal branch thrombosis → sharply demarcated red-blue area = Zahn infarct (pseudo-infarct) — no necrosis; only hepatocellular atrophy + sinusoidal congestion.

3. Impaired Intrahepatic Blood Flow

Causes

• Cirrhosis = most common intrahepatic cause of portal obstruction.
• Sickle cell disease → sinusoids packed with sickled RBCs → panlobular necrosis.
• DIC → sinusoidal occlusion.

Passive congestion & centrilobular necrosis (cardiac liver)

• Right-sided heart failure → passive centrilobular sinusoidal congestion → if persistent → centrilobular necrosis + cardiac sclerosis (fibrosis around central vein).
• Left-sided HF / shock → hepatic hypoperfusion + hypoxia → centrilobular ischemic necrosis.
• Combined L+R HF → nutmeg liver — centrilobular hemorrhagic necrosis + pale midzonal areas.

Peliosis hepatis

• Sinusoidal dilation from impaired hepatic blood efflux.
• Associated with anabolic steroids, rarely OCPs.
• Complication: intra-abdominal hemorrhage.

4. Hepatic Vein OUTFLOW Obstruction

A) Budd-Chiari syndrome (hepatic vein thrombosis)

• Thrombosis of ≥ 2 major hepatic veins.
• Causes:
  • Myeloproliferative diseases (PV, ET) and cancers → sluggish flow
  • Pregnancy / postpartum / OCPs → hypercoagulability
• Gross: swollen, red-purple liver with tense capsule.
• Micro: centrilobular congestion + necrosis.
• Sx: hepatomegaly, weight gain, ascites, abdominal pain.
• Tx: portosystemic shunt → considerably improves prognosis.

B) Sinusoidal obstruction syndrome (veno-occlusive disease)

• Toxic injury to sinusoidal endothelium → endothelial cells slough → emboli → outflow blockage.
• RBCs leak into space of Disse; stellate cell proliferation → fibrosis of terminal hepatic vein branches.
• Classic setting: first month after bone marrow transplantation (chemo drugs + total body irradiation).

💡 High-yield: Zahn infarct = intrahepatic portal vein thrombosis → pseudo-infarct (atrophy + congestion, no necrosis). Nutmeg liver = combined L+R heart failure. Budd-Chiari = hepatic vein thrombosis (myeloproliferative, OCPs, pregnancy) → centrilobular congestion + necrosis → portosystemic shunt. VOD/SOS = sinusoidal endothelial injury, classic post-BMT. Portal vein thrombosis → portal HTN (splenomegaly, varices, ascites).