Right and left portal branches, hepatic sinusoids, hepatic veins and IVC
Termination
The right and left portal branches accompany the hepatic artery and bile ducts into the portal tracts of each Couinaud segment; portal and arterial blood mix in the sinusoids and flow past the hepatocytes from the portal tract (zone 1) to the central vein (zone 3). Central veins unite into the right, middle and left hepatic veins, which enter the IVC just below the diaphragm at T8; the middle and left usually share a common trunk, and the caudate lobe drains straight into the IVC by small veins of its own.
Traced from the start
- Inferior mesenteric veinShort gastric and left gastro-omental veins
- Jejunal, ileal, ileocolic, right colic and middle colic veinsRight gastro-omental and pancreaticoduodenal veins
- Oesophageal veins (lower third)
- Splenic veinSuperior mesenteric veinLeft gastric (coronary) vein
- Hepatic portal vein
- Right and left portal branches, hepatic sinusoids, hepatic veins and IVC
Detail
- Hepatic blood flow
- About 1500 mL/min, roughly 25% of cardiac output
- Zone 1 (periportal)
- Best oxygenated; oxidative metabolism, gluconeogenesis
- Zone 3 (centrilobular)
- Least oxygenated; richest in cytochrome P450
- Hepatic veins
- Right, middle and left into the IVC at T8; no valves
When it goes wrong
Hepatic vein thrombosis (Budd-Chiari syndrome: polycythaemia vera, oral contraceptive, pregnancy, thrombophilia)
Posthepatic portal hypertension with tender hepatomegaly, ascites and abdominal pain; the caudate lobe hypertrophies because it drains directly into the IVC
Shock, right heart failure or paracetamol overdose
Zone 3 (centrilobular) necrosis, the region furthest from the oxygen supply and richest in the CYP450 enzymes that generate NAPQI
Transjugular intrahepatic portosystemic shunt (TIPS)
A stent from a hepatic vein into a portal branch lowers portal pressure for refractory variceal bleeding or ascites, at the price of hepatic encephalopathy
Wedged minus free hepatic venous pressure measured through the jugular vein
Hepatic venous pressure gradient, the standard measure of sinusoidal portal hypertension
Practise this structure
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