The Liver:Blood supply, Portal Hypertension

and Portosystemic AnastomosesRachael Edgar and Ellie Borton

The blood supply of the LiverThe liver receives blood from two sources.

What are they?Arterial supply from Hepatic Artery (30%)Venous supply from Hepatic Portal Vein (70%)

The Hepatic Portal vein comes from?Splenic vein Superior mesenteric vein

What are the components of the portal triad?Bile ductPortal veinHepatic artery

The portal vein and hepatic artery drain into the central vein.

Acini and LobulesHepatic Acinus

Functional unit liverImportant is Line connecting 2 portal triads &

extends out to 2 adjacent central veinsDif areas oxygenation

Hepatic LobuleSmall physical division of the liverHexagon with vein in the centre, periphery has

portal triads

Where does the central vein drain to?Hepatic vein

Portal HypertensionWhat happens?

Prolonged damage to the hepatocytes causes fibrosis (scarring)

Blood supply via the hepatic portal vein is blocked and the pressure within it rises

This causes a ‘back up’ of blood in the hepatic portal vein

Collaterals occur within the systemic venous system

What are the main sites of the collaterals?Azygous veins (at gastro-oesophageal junction)RectumAnterior abdominal wall via umbilical vein

What are the clinical consequences of portal hypertension?Oesophageal varicesRectal varicesCaput medusa

Oesophageal varices

Caput medusa

Rectal VaricesThese are found higher in the rectal canal

(found in mid rectum) than haemorrhoids.

Haemorrhoids • Common condition caused by ‘disrupted

& dilated’ anal cushions - symptomatic

• May be classified as internal or external in relation to pectinate line

• Symptoms of bleeding, pain or itch, may be due to enlargement, inflammation, prolapse or thrombosis