Liver- Overview
The liver is a vital intra-abdominal organ necessary for life. It is considered as “the biochemical factory” of the body as it accounts for a number of metabolic functions such as toxic substance removal from the body (detoxication), plasma protein synthesis, hormonal output and production of substances necessary for digestion, glucose metabolism (glycogenolysis, glucogenesis), glucagon storage, lipid metabolism (cholesterol and trigyceride synthesis), erythrocyte destruction, etc. It is located in the upper right part of the abdomen. The liver has a dual blood supply, from the portal vein and the hepatic artery. The portal vein, accounting for almost 74% of blood supply to the liver, transports venous blood from the gastrointestinal tract. The remaining 25% of blood supply to the liver comes from the hepatic artery, bringing arterial blood to the liver. The blood is then transported via the sinusoidal capillaries from the hepatic lobules to the hepatic venous network ending up to e hepatic veins and finally to the inferior vena cava. Hepatocytes produce bile, which is then collected within the biliary tubules forming the biliary ducts (cholangia). Intrahepatic bile ducts end into the extrahepatic ducts that form the left hepatic duct and eventually the common bile duct. The bile duct is situated on the river bed and contains bile that is secreted via the cystic duct into the common bile duct and finally into the duodenum and the remainder of the gastrointestinal tract.
Hepatic conditions are numerous. The most common ones are infections (hepatitis A,B,C,D,E), alcoholic liver disease, fatty liver, cirrhosis , cancer, toxic and drug-induced liver diseases (e.g. paracetamol induced). There are a number of pediatric liver diseases (biliaries atresia, a1-antitrypsin insufficiency, Alagille syndrome, progressive intrahepatic cholestasis and Langerhans cell histiocytosis, etc.).
The clinical signs of liver disease varies and includes jaundice (yellowish pigmentation over the sclera of the eyes), feces discoloration, dark color urine, ascites (abdomen dilatation), signs of portal hypertension, edemas, fatigue, ecchymosed and hemorrhagic tendency due to clotting disorders, hepatic encephalopathy, hepatonephric syndrome, etc.
Diagnostic tests include biochemistry tests (transaminases SGOT-SGPT, ALP, LDH, γGT), viral tests, ultrasonography (with or without contrast dye administration), CT scan, MRI, magnetic resonance cholangiopancreatography (MRI-MRCP), liver biopsy, etc.
There are various techniques to enhance liver function. Liver transplant is often the solution to end-stage non reversible liver damage.
Liver transplantation Indications
The indications for liver transplantation are the following:
- Acute, fulminant, or subacute liver failure
- End stage chronic liver disease
- Liver malignancy
- Metabolic disease
- Parenchymal disease complications (ascites, encephalopathy)
- Non tolerable quality of life due to liver disease
The above categories include a series of conditions (primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis, Laennec cirrhosis, cirrhosis due to viral hepatitis, alcoholic cirrhosis, amyloidosis, Wilson disease, alpha-1 antitrypsin, polycystic liver disease, hepacelula carcinoma, choangiocarcinoma, fibrolamellar hepatoma, fibrocystic liver disease, sarcoidosis, hemochromatosis, billiary atresia, Caroli disease, Criggler-Najjar syndrome, neonatal hepatitis, cryptogenic cirrhosis, etc.
With regard to patients with malignant liver disease, the widely acceptable Milan criteria consider the following patients as eligible for liver transplantation:
a) patients with a solitary tumour measuring <5cm.
b) patients with two or three tumours < 3cm each.
Specific criteria have been described with regard to the appropriate time to perform the transplant. Generally, the liver transplantation is considered imperative when:
a) The estimated survival due to hepatic failure is <1 year.
b) The quality of life due to liver disease is not acceptable.
Liver transplantation technique
Liver transplantation is classified as orthotopic (which is the most frequent one) and ectopic – auxiliary and atopic (orthotopic auxiliary).
In orthotopic liver transplantation the affected liver is removed and a new liver graft is placed. It is a method initially described by Starzl (1963) and has currently prevailed in most transplantation centres.
The atopic or auxiliary liver transplantation includes the placement of the graft at an ectopic position of the liver without resecting the affected liver. Finally, the paratopic liver transplantation includes the removal of the affected organ (e.g. left lobe) and the placement of part of the live graft. In practice, the preservation of the affected liver or part of it involves many risks and creates problems, limiting the application of auxiliary transplantation methods.
Successful transplantation is based on the right selection of the donor and the recipient based on strictly defined criteria. Usually, the liver graft is taken from a cadaveric donor using a specific technique (hot or cold preparation) and the preservation is performed using ice and special solutions. The organ is prepared in the operation room on the back table.
Orthotopic transplantation usually includes the entire liver transplant. In liver transplantations to children, a part of the graft is used after cutting down liver or splitting liver or even a part of the liver harvested from a living donor.
The orthotopic transplantation technique involves the dissection of the liver ligaments, the preparation of the hila, the preparation and ligation of the bile duct and the hepatic artery, portal vein preparation and venovenous shunt, inferior vena cava exclusion in the subhepatic and suprahepatic space, and removal of the diseased liver. Subsequently, the graft and shunts are placed (suprahepatic and subhepatic shunt of the inferior vena cava, portal vein shunt, reperfusion, hepatic artery shunt, common bile duct shunt).
A variation of the shunt of the inferior vena cava is the technique called “piggyback” where no venovenous shunt is performed, the continuation of the inferior vena cava of the recipient is divided, the lower part of the inferior vena cava is stapled and its upper part is shunted with the recipient’s inferior vena cava at the hepatic vein outlet.
Post operative follow-up is intensive and aims at supporting the patient and the liver transplant functioning and at preventing rejection through the administration of immunosuppressive drugs.
Liver transplantation is applied at specialized and appropriately certified centers, having the necessary equipment and surgical team experience, and requires the collaboration of a number of specialties and qualified personnel.
Pancreas – Overview
The pancreas is a gland of the digestive tract producing and secreting the pancreatic juice containing enzymes important for the digestive function (exocrine function) and many hormones, the most important of which are insulin and glucagon (endocrine function). Pancreas plays an important role in regulating the glucose levels in the blood and in diabetes mellitus pathogenesis.
Pancreas transplantation Indications
Diabetes mellitus and its complications are treated with a special diet, pharmaceutical preparations and mainly insulin. In cases of insulin dependent diabetes and its complications, surgical treatment with pancreas transplantation is a treatment option. It is a highly demanding procedure necessitating experience in pancreatic surgery and transplantation, as well as in the postoperative handling of patients and the management of potential complications.
Patients suffering from diabetes mellitus type I (insulin-dependent) and/or diabetic nephropathy are candidates for pancreatic transplant. Usually double concurrent kidney/pancreas transplantation is performed. However, pancreas transplantation may be performed solely if a kidney transplantation has preceded it or, in very rare cases, pancreas transplantation solely.
Pancreas transplantation Technique
The standard technique includes transplant of the entire new pancreas with part of the duodenum placed in one iliac fossa, and it is usually followed by kidney transplant in the other iliac fossa. The splenic and upper mesenteric artery of the graft are shunted with the outer iliac artery of the recipient, the transplant portal vein and the recipient’s external iliac artery, while part of the duodenum is shunted with the bladder or part of the small intestine (jejunum).
This transplant treats the diabetes clinical syndrome and the patient is freed from using insulin. Postoperatively an immunosuppressive drug regimen is administered to prevent transplant rejection. This medication is necessary in any case for the survival of the renal transplant.
Another option is to transplant pancreatic islets (Langerhans islets). This technique includes the removal of the pancreas from the donor, the exclusion and special processing of the islets and their injection to the recipient’s portal vein. This method is less invasive but it is not widely applied since, despite raising high hopes initially, there are studies that show that with time the islets functionality gradually declines. More studies are required to document the efficacy of this method.
