Portal-systemic Anastomoses – Portal System

00:00 So the portal systemic anastomoses; these are connections between the venous portal system and the systemic circulation and typically these are very narrow quiescent connections that do not typically conduct a significant volume of blood, so they are usually quite quiescent, they are usually not very active; however when the portal circulation is compromised, maybe liver disease, cirrhosis or pressure from a neighbouring tumor, blood can’t flow through the liver adequately because it is blocked. But the pressure forces that blood to return to the heart via these alternative routes and there are a number of them, so if we have cirrhosis or liver disease and the architecture of the liver is preventing the hepatic portal vein taking blood through then it seeks out these alternative routes, these portal systemic anastomoses and we have 4 of them, we have them between the oesophagus and the stomach, oesophageal and gastric veins, we have them occurring between the rectal veins, between the systemic and portal parts of those rectal veins, we have para-umbilical and we have epigastric veins and we have colic and retroperitoneal veins and we will explore these in the next few slides. So we have portal hypertension, more than expected blood passes through these portal-systemic anastomoses leading to these veins becoming dilated and what we know as varices.