Pediatric Liver Transplantation: From Adults to Children and Back

“Bennie Solis was a tiny spot in the universe, and a flawed one at that. The son of poor Spanish American parents, he was born with biliary atresia (…). By this time we had performed nearly two hundred liver transplantations in dogs (…). However, nothing of what we had done in advance could have prepared us for the enormity of the task. Several hours were required just to make the incision and enter the abdomen. Every piece of tissue that was cut contained the small veins under high pressure that had resulted from the obstruction of the portal vein by the diseased liver. Inside the abdomen, Bennie’s liver was encased in scar tissue left over from operations performed shortly after his birth. His intestine and stomach were stuck to the liver in this mass of bloody scar. To make things worse, Bennie’s blood would not clot. Several of the chemical and other factors which are necessary for this process were barely detectable. He bled to death as we worked desperately to stop the hemorrhage…” &.

Since this dramatic description of the first liver transplant performed by Thomas E. Starzl in Denver on March 1, 1963 liver transplantation has come a long way to become the therapy of end-stage liver disease in children and adults.

Some of the most significant advancements in the technical evolution of liver transplantation have been generated by the need to overcome the shortage of cadaveric organs for children. The epidemiology of end-stage liver disease and brain death in children are different:  most pediatric candidates for liver replacement are below two years of age, whereas the few children who die of causes that lead to brain death are above five years of age &.  Prior to the introduction of new techniques, mortality on pediatric waiting lists was as high as 50% &.

The field of pediatric liver transplantation was revolutionized by applying the same surgical techniques used in resecting liver tumors for reducing liver grafts to fit to the size of the recipient child. From cadaveric donors with body weights up to 12 times the weight of a pediatric recipient, liver grafts (usually left lateral segments) for children below ten kilos could be prepared &. This however meant diverting liver grafts away from the increasingly long waiting list of adults.  

In order to eliminate competition between pediatric and adult waiting lists, two new techniques were reported in 1988: split liver and living-related liver transplantation &. From one procedure to the other there has been an “osmotic” process. Lessons learned in the procurement of the left lateral segment from living donors have been transferred to the “in situ” split liver technique which has made split liver transplantation a safe and effective procedure for both pediatric and adult recipients :.  The success obtained in most countries with split liver transplants has virtually eliminated the need of living donor operations &.  Children are now, finally, a privileged patient population with almost no mortality on waiting lists &.

Segmental liver transplantation, from cadaveric or living donors, was created to overcome the adult donor to pediatric recipient size mismatch.  More recently, segmental liver transplantation has become a way to face the increasing gap between the number of donors, which seems to have reached a plateau in many countries, and the constantly increasing number of adult candidates to liver replacement &.

Living donor liver transplantation for adults is rapidly expanding and the most widely used technical variant of this procedure is the procurement and transplantation of the right lobe &. Contrary to the pediatric situation, where one has to make sure that the graft is not too big, in the adult patient it is vital to provide the recipient with enough liver mass. It seems clear that transplantation of liver grafts that are less than 1% of the recipient body weight is unsafe. The right lobe of an adult donor, in  most cases, provides the appropriate parenchymal mass for an adult recipient.

Living donor liver transplantation for adults has proven to be a safe and effective procedure for recipients with an acceptable risk of complications and death for the donor, although the rapid proliferation of programs might be associated with increasing risks.  This procedure has demonstrated a valuable lesson: that the liver of one adult can sustain the life of two adults &.

Operations similar to those performed in the adult living donor can be performed in situ in the cadaveric donor, generating two grafts large enough to be transplanted into two recipients & :.  Of course, in this situation, the damage suffered by the liver caused by brain death, procurement, preservation and transplantation have to be taken into account when calculating a safe graft-to-recipient weight ratio. But split liver for two adults might in the future be an important way to increase the number of liver transplants.

Most of what has been learned in segmental liver transplantation derives from the imagination and technical expertise that transplant surgeons have used to help children suffering the ravages of end-stage liver failure.  The results are astonishing; there are now surgical procedures that can virtually eliminate the mortality in pediatric waiting lists.  

One important byproduct of pediatric segmental transplantation is the confidence gained in recognizing that the liver can be seen as a two-graft organ that can be adapted to the size of two recipients :.  Adult patients are already benefiting from the increased application of split liver techniques and, as more transplant centers adopt splitting, more waiting recipients will benefit in the future.