Portal shunt operation

In the light of a possible shunt operation, it has become more important to obtain additional information on the arterial blood supply to the liver. As regards cirrhosis with portal hypertension, arteriographic investigations have shown that the more the blood flow through the... 

Liver transplantation not only removes the continued risk of variceal bleeding, but also eliminates the underlying liver disease causing portal hypertension. However, due to the scarcity of liver donors, limited financial resources and the life-long immunosuppression required, this major surgical intervention can only rarely be considered - perhaps in cases where a previous shunt operation or the creation of a TIPS was not possible. The survival rate for transplantation is higher than when recurrent bleeding is treated by repeated sclerotherapy (73% versus 17% after 4 years). The indication for transplantation (e. g. cirrhosis Child B or C) should be set as early as possible, (s. p. 872)... 

Previous shunt operations and TIPS need to be removed in order to guarantee that the transplanted liver is sufficiently supplied with portovenous blood. In these cases, the portal system is checked preoperatively for thromboses by means of colour-encoded duplex sonography and X-ray techniques. In any case, the confluence of superior mesenteric vein and splenic vein must be free. (391) The main advantage of portacaval end-to-side anastomosis is its low thrombosis rate of < 5% in addition, there is no need for a distal shunt ligature. In shunts distal to the hilus (mesocaval, distal splenorenal), no preparation of the liver hilus is required however, in 10% of cases, these shunts show portal vein thrombosis (in TIPS, up to 15%). Usually, all surgical shunts are disconnected or ligated before the liver transplantation is completed in order to... 

Plasma cholinesterase determinations have been helpful in assessing the suitability of a patient for shunt operations in portal hypertension or for liver transplantation (E18). Obstructive jaundice is not accompanied by a reduction of cholinesterase activity unless there is also damage to the hepatocytes. In cases of fatty liver, the plasma cholinesterase activity is generally normal or high. As indicated above, there is a positive correlation between the enzyme activity and plasma lipids or lipoproteins (CIO, C16, K36). 

Most HE episodes in patients with chronic liver disease are precipitated by events such as oral protein load, gastrointestinal bleeding, obstipation, infection, especially peritonitis, hypokalemia and alkalosis complicating the use of diuretic drugs, administration of sedative drugs, for example for diagnostic procedures or induction of portal-systemic shunt via shunt operation or the TIPSS implantation. 

Splenoportographic procedures allow an accurate depiction of the portal vein and its afferent flow areas. Despite the development of new techniques, these methods are of importance in clarifying the cause of portal hypertension, and they are (still) deemed to be a prerequisite for operations aimed at reducing the pressure and vol-mne in the portal venous circulation. Vessels with a diameter of <1 cm are unsuitable for long-term patency of a shunt. Direct and indirect procedures are available. (16, 35)... 

A study by Rao et al." measured the levels of amino acids using in vivo cerebral microdialysis in the frontal cortex of portacaval-shunted rats administered ammonium acetate to precipitate severe portal-systemic encephalopathy. In comparison to sham-operated control rats, tryptophan levels increased by 63% along with those of other amino acids. However, the experimental animals did not have a significant increase in extracellular fluid concentration of tryptophan, suggesting that increased spontaneous release of tryptophan in cerebral cortex is not implicated in the pathogenesis of hepatic coma. 

---