The liver is the body's principle chemical factory. It receives all nutrients, drugs, and toxins absorbed from the intestines and performs the final stages of digestion, converting food into energy and replacement parts for the body. The liver also filters the blood of all waste products, removes and detoxifies poisons and excretes many of these into the bile. It processes other chemicals for excretion by the kidneys. The liver is also an energy storage organ, changing food energy to a chemical called glycogen that can be rapidly converted to fuel.
As the liver fails, all of its functions diminish. Nutrition suffers, toxins build up, and waste products accumulate. Scar tissue builds up on the liver if disease is of long duration. As the liver scars, blood flow is progressively restricted in the portal vein, which carries blood from the stomach and abdominal organs to the liver. The resulting high blood pressure (hypertension) causes swelling of and bleeding from the blood vessels of the esophagus. Severe jaundice, fluid accumulation in the abdomen (ascites), and deterioration of mental function, due to the build-up of toxins in the blood (liver encephalopathy), eventually occur, leading to death.
Among the many causes of liver failure that bring patients to transplant surgery are:
scarring or abnormality of the biliary system accounts for roughly another 20%
the remainder comes from selected cancers, other uncommon diseases, and a situation called fulminant liver failure
Fulminant liver failure most commonly happens during acute viral hepatitis, but it is also the result of mushroom poisoning by Amanita phalloides and toxic reactions to some medicines, like an overdose of acetaminophen. This is a special category of candidates for liver transplant because of the speed of their disease and the immediate need of treatment.
The first human liver transplant was performed in 1963, and since then, thousands of liver transplants are done every year. Since the introduction of ofcyclosporine (a drug that suppresses the immune response that rejects the donor organ), success rates for liver transplantation have reached 85%.
Precautions
Patients with advanced heart and lung disease, who are HIV positive, and who abuse drugs and alcohol are poor candidates for liver tranplantation. Their ability to survive the surgery and the difficult recovery period, as well as their longterm prognosis, is hindered by their conditions.
Orthotopic transplantation is the replacement of a whole diseased liver with a healthy donor liver.
Heterotopic transplantation is the addition of a donor liver at another site, while the diseased liver is left intact.
Reduced-size liver transplantation is the replacement of a whole diseased liver with a portion of a healthy donor liver. Reduced-size liver transplants are most often performed on children.
When an orthotopic transplantation is performed, a segment of the inferior vena cava attached to the liver is taken from the donor as well. The same parts are removed from the recipient and replaced by connecting the inferior vena cava, the hepatic artery, the portal vein and the bile ducts.
When there is a possibility that the afflicted liver may recover, a heterotopic tranplantation is performed. The donor liver is placed in a different site, but it still has to have the same connections. It is usually attached very near the original liver, and if the original liver recovers, the donor shrivels away. If the original liver does not recover, it will shrivel, leaving the donor in place.
Reduced-size liver transplantation tranplants part of a donor liver into a patient. It is possible to divide the liver into eight pieces, each supplied by a different set of blood vessels. Two of these pieces have been enough to save a patient in liver failure, especially if the patient is a child. It is therefore possible to transplant one liver into at least two patients and to transplant part of a liver from a living donor and have both donor and recipient survive. Liver tissue grows to accommodate its job so long as there is initially enough of the organ to use. Patients have survived with only 15-20% of their original liver, provided that 15-20% was healthy.
Availability of organs for transplant is a current crisis in the transplantation business. In October 1997, a national
distribution system was established that gives priority to the sickest patients closest in location to the donor liver, but makes livers available nationally. It is now possible to preserve a liver out of the body for 10-20 hours by flushing it with cooled solutions of special chemicals and nutrients, so it can be transported across the country.
Preparation
Before transplantation takes place, the patient is first determined to be a good candidate for transplantation by going through rigorous medical examination. A suitable candidate boosts their nutritional intake in order to ensure that they are as healthy as possible before surgery. Drugs are administered that will decrease rejection after surgery. Consultation with the patient, as well as any family, is conducted to explain the surgery and its complications. Psychological counciling is recommended.
Successfully receiving a transplanted liver is only the beginning of a life-long process. Patients with transplanted livers have to stay on immunosuppressant drugs for the rest of their lives to prevent organ rejection. Although many can reduce the dosage after the initial few months, virtually none can discontinue drugs altogether. Prednisone, azathioprine, and tacrolimus are often combined with cyclosporine for better results. Newer immunosuppressive agents are coming that promise even better results. In spite of immunosuppressants, rejection occurs most of the time and requires additional medication. In some cases it cannot be reversed, and retransplantation becomes necessary.
National Transplant Waiting List By Organ Type
(June 2000)
Organ Needed
Number Waiting
Kidney
48,349
Liver
15,987
Heart
4,139
Lung
3,695
Kidney-Pancreas
2,437
Pancreas
942
Heart-Lung
212
Intestine
137
Risks
Early failure of the transplant occurs once in four surgeries and has to be repeated. Some transplants never work, some succumb to infection, and some suffer immune rejection. Primary failure is apparent within one or two days. Infections happen in half the patients and often appear during the first week. Rejection usually starts at the end of the first week. The surgery itself may need revision because of narrowing, leaking, or blood clots at the connections.
There are potential social and economic problems, psychological problems, and a vast array of possible medical and surgical complications. Close medical surveillance must continue for the rest of the patient's life. Infections are a constant risk while on immunosuppressive agents, because the immune system is supposed to prevent them. A way has not yet been devised to control rejection without hampering immune defenses against infections. Not only do ordinary infections pose a threat, but because of the impaired immunity, transplant patients are susceptible to the same "opportunistic" infections that threaten AIDS patients—pneumocystis pneumonia, herpes and cytomegalovirus infections, fungi, and a host of bacteria.
Immunosuppression also hinders the body's ability to resist cancer. All the drugs used to prevent rejection increase the risk of leukemias and lymphomas.
There is also a risk of the original disease returning. Hepatitis virus still inhabits the patient, as does the urge to drink alcohol. Newer antiviral drugs hold out promise for dealing with hepatitis, and Alcoholics Anonymous (AA) is the most effective treatment known for alcoholism.
Drug reactions are also a continuing threat. Every drug used to suppress the immune system has potential problems.
BOOKS
Dienstag, Jules. "Liver Transplantation." In Harrison's Principles of Internal Medicine, ed. Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.
Gartner, J. Carleton. "Liver Transplantation." In Nelson Textbook of Pediatrics, ed. Richard E. Behrman. Philadelphia:W. B. Saunders Co., 1996.
Roberts, John P. "Liver Transplantation." In Cecil Textbook of Medicine, ed. J. Claude Bennett and Fred Plum. Philadelphia: W. B. Saunders Co., 1996.
PERIODICALS
Butler, A., and P. J. Friend. "Novel Strategies for Liver Support in Acute Liver Failure." British Medical Bulletin 53 (1997): 719-729.
Cao, S., C. O. Esquivel, and E. B. Keeffe. "New Approaches to Supporting the Failing Liver." Annual Review of Medicine 49 (1998): 85-94.
Lanza, R. P and D. K. Cooper "Xenotransplantation of Cells and Tissues: Application to a Range of Diseases, from Diabetes to Alzheimer's." Molecular Medicine Today 4 (Jan. 1998): 39-45.
Luxon, B. A. "Liver Transplantation: Who Should Be Referred—And When?" Postgraduate Medicine 102 (Dec. 1997): 103-108, 113.
Rao, V. K. "Posttransplant Medical Complications" Surgical Clinics of North America 78 (Feb. 1998):113-132.
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