What is portal hyper tension?

Answer 1

Portal hypertension is defined as a sustained elevation of portal pressure above normal.

Normal pressure in the portal vein is low (5 to 10 mmHg)

Portal hypertension (>10 mmHg) most commonly results from increased resistance to portal blood flow.

Causes

a combination of increased portal venous inflow and increased resistance to portal blood flow

Portal hypertension may arise from increased blood flow, but the low outflow resistance of the normal liver makes this a rare clinical problem.

pathogenesis

increased splanchnic venous inflow

Vasodilators (Nitric oxide)

Increased resistance to portal blood flow

Prehepatic causes

Intrahepatic causes: classic sinusoidal cause -- cirrhosis

Posthepatic causes

Clinical Features

development of portal-systemic collateral channels

splenomegaly with hypersplenism

ascites

Answer 2

Portal hypertension is a pathology (i.e. a disease state). It's an increase in the blood pressure in the portal vein, which carries blood containing nutrients from the digestive system to the liver. It's a very large blood vessel, and its contents are crucial: it's one of the most important routes by which we get nutrition from what we eat.

If the liver becomes diseased (such as in cirrhosis, where the liver shrinks and hardens owing to scarring, either from chronic alcohol abuse or hepatitis) blood is unable to flow as easily into the liver. More blood is arriving at the liver in the portal vein than is leaving. As a result, pressure builds up in the portal system. This has a domino effect back down the venous system, increasing the pressure elsewhere.

This increase in pressure is damaging to blood vessels, so to relieve the pressure, there are several consequences:

1) Portocaval anastomoses: These are 'shunts' where blood can force its way into the great systemic circulation to reduce overall portal pressure. Some of these are close to the skin which cause visible varicose veins on the surface of the abdomen (called 'caput medusae' because they look like the Medusa's head with lots of 'snakes' winding off). The most clinically serious point of anastomosis is in the oesophagus (the tube from your mouth to your stomach). Here, veins can widen and eventually burst if the pressure becomes too great. This causes very high pressure blood to squirt into the oesophagus and down into the stomach. This is why those in end stage liver disease may often vomit blood.

2) Splenomegaly - the spleen can also enlarge which will cause it stop working, which has serious consequences. Without it, we can't break down old red blood cells and re-use them.

3) Ascites - this is a very swollen abdomen which is full of fluid. The increase in pressure forces fluid out of the blood vessels and into the peritoneal cavity. Those with ascites will have tell-tale 'bulging flanks' (i.e. their sides will bulge out when they lie flat) and 'shifting dullness' when a doctor percusses their abdomen.