immunology allergic disorders
Liver Transplantation
Liver donors
Nearly all donated livers come from size- and ABO-matched brain-dead (deceased), heart-beating donors. Prospective tissue typing and human leukocyte antigen (HLA) matching are not always required. ABO-incompatible liver transplants have been transplanted successfully in children < 2 years; in older children and adults, these transplants are not used because there is a high risk of rejection and bile duct damage (ductopenia) with cholestasis, which requires retransplantation. Annually, more than 500 transplants in the US come from living donors, who can live without their right lobe (in adult-to-adult transplantation) or the lateral segment of their left lobe (in adult-to-child transplantation). Advantages of living donation for the recipient include shorter waiting times and shorter cold ischemic times for explanted organs, largely because transplantation can be scheduled to optimize the patient’s condition. Disadvantages to the donor include mortality risk of 1/600 to 700 (compared with 1/3300 in living-donor kidney transplantation) and complications (eg, bile leakage, bleeding) in up to one fourth. Clinicians must make every effort to prevent psychologic coercion of donors. A few livers come from deceased, non–heart-beating donors (called donation-after-cardiac-death [DCD] donors), but in such cases, bile duct complications develop in up to one third of recipients because the liver had been damaged by ischemia before donation. Donor (deceased or living) risk factors for graft failure in the recipientinclude Age > 50 Hepatic steatosis Elevated liver enzymes, bilirubin, or both Prolonged stay in an intensive care unit Hypotension requiring vasopressors Hypernatremia Possibly transplantation from female donors to male recipients But because imbalance between supply and demand is greatest for liver transplants (and is growing because prevalence of hepatitis-induced cirrhosis is increasing), livers from donors>50, livers with longer cold ischemia times, those with fatty infiltration, and those with viral hepatitis (for transplantation into recipients with viral hepatitis-induced cirrhosis) are increasingly being used. Additional techniques to increase supply include Split liver transplantation:Deceased-donor livers are divided into right and left lobes or right lobe and left lateral segment (done in or ex situ) and given to 2 recipients Domino transplantation:Occasionally, a deceased-donor liver is given to a recipient with an infiltrative disease (eg, amyloidosis), and the explanted diseased liver is given to an older recipient who can benefit from the diseased liver but is not expected to live long enough to experience adverse effects of transplant dysfunction. Despite these innovations, many patients die waiting for transplants. Liver-assist devices (extracorporeal perfusion of cultured hepatocyte suspensions or immortalized hepatoma cell lines) are used in some centers to keep patients alive until a liver is available or acute dysfunction resolves. 