Liver Transplantation

Liver transplantation is a surgical procedure whereby a whole liver is removed from a cadaveric donor and implanted into a recipient in an effort to restore normal hepatic function. Used as a primary treatment for end-stage liver disease (ESLD) resulting from cirrhosis, autoimmune liver pathologies, some liver cancers, and hepatitis, the first cadaveric liver transplantation was performed in Pittsburgh, Pennsylvania, in 1967.

Since the advent of the procedure, the demand for donor livers has grown. Experts have begun meeting this challenge in several ways. In the 1980s, fueled by the need to transplant pediatric donors with smaller livers, surgeons began transplanting reduced-size allografts for younger patients. This advance led to split-liver transplantation whereby one cadaveric donor liver is separated for implantation into two recipients. Although each section is smaller than a whole organ, the inherent ability of the liver to regenerate in response to injury or volume loss facilitates procedures of this nature. The surgical skills and knowledge gained from the aforementioned interventions later enabled surgeons to begin performing partial liver transplants from living donors.

While these and other advances help ameliorate the disparity between supply and demand, persisting shortages still mandate the prudent allocation of available livers. In 2002, the United Network for Organ Sharing (UNOS) began using the model for end-stage liver disease (MELD) to evaluate potential liver [Page 1027]recipients based on medical urgency. This new method of organ allocation bases recipient selection on parameters tied to patient mortality instead of absolute waiting time. In addition to patient evaluation by the UNOS MELD score, patients are also evaluated for potential contraindications to transplantation such as limited cardiovascular/respiratory function, advanced malignancy, or active infection such as HIV.

Once a liver recipient has been identified, procurement is completed via one of several surgical methods depending on the type of donation and the specific donor's anatomy. All cadaveric liver procurements involve a long midline incision necessary to expose both the thoracic and abdominal cavities and rule out malignant pathologies.

The majority of hepatic surgical dissection is then performed before or after a systemic flush of the donor's blood with cold preservation solution. To ensure the organ is perfused with preservation solution, the main blood vessels to and from the liver are the last to be transected. In contrast, living donor transplantation involves a less invasive donor incision which exposes only enough of the liver as is necessary for procurement. Additionally, extra care must be taken to ensure that dissection of the donated portion of the liver does not interfere with the normal perfusion and function of the remaining part.

Since the inception of liver transplantation, advancements in organ preservation, better immunosuppressant therapies, and effective management of complications have led to a five-year allograft survival rate of 71 percent and a patient survival rate of 80 percent in the United States. Complications include infection, acute or chronic rejection, vascular occlusion, and renal dysfunction secondary to liver transplantation. In a study of 181 liver transplants performed between 1998 and 2000, researchers found one-week acute renal dysfunction rates of approximately 39 percent and chronic renal dysfunction was discovered in about 6 percent of patients during long-term follow-up.

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