Portal hypertension

The portal vein is the main blood supply to the liver bringing the products of digestion from the intestine. There are thousands of branches off the portal vein that feed the lobules in the liver. As the scarring of the liver tissue extends around these tracts and link up, so the blood flow is impeded. This increases the pressure in the portal vein itself as the backed up blood tries to make its way back to the heart. This is called portal hypertension.

With its route blocked and with pressure increasing, the blood tries to find a new way back to the heart. It starts bypassing the liver creating small channels called varices. The most common place for varices to develop is in the lining of the stomach and in the gullet (oesophagus). Varices are small and delicate and there is a significant risk of internal bleeding and that the varices may rupture. Oesphagus varices are more likely to rupture than those in the stomach.

If this happens people may vomit up blood in which case they should seek medical help immediately. In some cases bleeding from the varices can be slow and blood is not vomited up but passes through the intestines where it is partially digested. It appears as black, smelly diahorrea (melaena). Medical help must again be sought immediately.

Portal hypertension means that the blood that bypasses the liver is not filtered for poisons and toxins. Amino acids and ammonia, which is a toxic by product of protein metabolism, are particularly dangerous if they are not eliminated from the body and pass into the bloodstream. This can lead to hepatic encephalopathy (literally liver caused mental impairment). Encephalopathy is a state of impaired or altered mental status. In its mild form there may be short term memory loss, forgetfulness, slurring of speech, small personality or behavioural changes, and changes in sleep patterns.

In its severe form symptoms include severe loss of memory i.e. not knowing the date, year, name or address, confusion, inappropriate behaviour, poor coordination, asterixis- uncontrollable flapping of the hands, foul smelling breath (fetor hepaticus) and coma (hepatic encephalopathy). Encephalopathy is significantly more severe and frightening than the sort of confusion, brain fog and memory impairment experienced by many people with non-cirrhotic hepatitis C.

The treatment of hepatic encephalopathy involves the removal of all drugs that require detoxification in the liver. It may also entail the reduction of protein intake as a high protein diet may make these symptoms worse. Restricting the amount of protein in the diet lowers the levels of amino acids and ammonia in the bloodstream and brain. Doctors may recommend eating less than 40 grams of protein a day, and will prescribe lactulose or neomycin to lower ammonia production. Protein from vegetables and fish are usually recommended rather than meat.

Ammonia can also get into the bloodstream and cause encephalopathy even without portal hypertension. The cirrhotic liver may fail to properly process ammonia and so it passes to the colon and from there into the bloodstream.

Portal hypertension is also a factor in the development of ascites. This is a swelling in the abdomen due to fluid retention. The liver synthesises the protein albumin. Albumin regulates the exchange of water between blood and tissues. The combination of the high pressure in the veins and capillaries caused by portal hypertension and insufficient albumin leads to builds up of lymph fluid in the abdomen, usually causing visible swelling of the veins in the skin over the abdomen.

If your abdomen is swollen, the doctor will check for ascites by tapping the flanks and listening for a dull thud and feeling the abdomen for a shifting wave of fluid.

Oedema is similar to Ascites except that the swelling caused by fluid retention occurs not in the abdomen but in the feet, ankles, legs or in the back.

Both Ascites and Oedema need to be treated with a low salt diet (since salt encourages water retention in the body), and possibly diuretics to increase salt loss via the kidneys.

The obstructed flow of blood through the portal vein (portal hypertension) causes the spleen to enlarge by causing an increase in pressure inside the vessels of the spleen. The spleen stores red and white blood cells and platelets (fragment of cells that are used to clot blood). An enlarged spleen traps platelets lowering levels in the blood which can lead to the inability of blood to clot. This is called Thrombocytopenia and is common in people with cirrhosis. You dont necessarily have any symptoms with an enlarged spleen, but you may feel pain or a heaviness in the upper left hand side of your abdomen, and a doctor will be able to tell if it is enlarged by palpitating the area (which means tapping the spleen area to listen for a percussive sound indicating where the edges of the organ are).

Portal hypertension leads to blood vessels in the gut becoming enlarged which in turn leads to low blood pressure. To compensate for this, constriction of blood vessels occurs elsewhere particularly in the kidneys leading to impaired function with rising serum creatinine levels. The mechanism that causes HRS is not entirely understood as yet.
In its mild form this kidney impairment can be treated with diuretics and the use of intravenous albumin. However, if liver function continues to diminish combined liver-kidney failure (hepatroenal syndrome HRS) can result. HRS is a life threatening condition that requires emergency treatment.