Auxiliary liver transplantation for acute liver failure.

In summary, the following principles are worth reiterating: 1. In the treatment of acute liver failure, protection of the native liver in anticipation that it will recover, but positioning of the allograft in a manner that optimizes its function for both the short and long term (in the event that the native liver does not recover) are important goals. Therefore, orthotopic positioning offers advantages over the heterotopic position in most cases. Development of better techniques for predicting native liver recovery might remove any of these advantages of the orthotopic position. 2. Other than the presence of fibrosis, the performance of a native liver biopsy does not appear to predict native liver recovery. The decision of whether to attempt auxiliary grafting must be based on an understanding of the natural history of the disease causing the acute liver failure. 3. The heterotopic position has the advantage of not requiring partial native hepatectomy in order to accommodate the allograft. However, except for the recent experience of Terpstra et al, this technique has carried a higher risk of venous outflow obstruction. It also requires additional space within the abdomen, usually mandating the use of prosthetic abdominal wall closures and the construction of venous conduits for portal venous inflow to the liver. There is the additional theoretical concern about competition for portal venous flow leading to eventual atrophy of the allograft liver. 4. Common events that follow liver transplantation result in changes in portal venous resistance within the liver, events that therefore alter the relative distribution of portal venous inflow between native and auxiliary livers. These events include reperfusion injury, allograft rejection, allograft viral infection (e.g., cytomegalovirus, Epstein-Barr virus, recurrent viral hepatitis), and native liver regeneration. Attempts to control portal venous flow to favor one liver over the other must account for the effect of these factors. 5. In general terms, auxiliary transplantation is not indicated for diseases in which the residual native liver either represents an ongoing threat to the recipient or is incapable of supporting life alone. This may be the case in both metabolic disorders and in cirrhosis. Most of the alleged difficulties of native hepatectomy are no longer relevant. Therefore, auxiliary transplantation is rarely if ever indicated for chronic liver disease and may not be of any additional benefit over total transplantation in the treatment of many metabolic disorders. 6. In the treatment of acute liver failure, the value of an auxiliary transplant over total transplant is obtained when the native liver recovers and the patient is withdrawn from immunosuppression. If further experience shows the effectiveness of this option, total liver transplantation with the requirement for life-long immunosuppression will no longer be appropriate for the treatment of patients with acute liver disease.