New UNOS rules: historical background and implications for transplantation management. United Network for Organ Sharing.

The algorithm for the allocation of donor hearts used by the United Network for Organ Sharing (UNOS) was changed in January 1999. The new scheme alters the medical urgency criteria from a 2-tiered to a 3-tiered system. Blood type O and blood type B candidates are less disadvantaged and pediatric candidates are somewhat advantaged with regard to adolescent donors. The new allocation algorithm allows an individual with life-threatening ventricular arrhythmias to be listed in the highest urgency status. Increased regulation will occur with the establishment of a review for the highest urgency status and the establishment of regional review boards.