How are heart transplant organs allocated?

Globally, the need for organ transplantation continues to exceed the supply of donor organs. The transplant community is organized under a nationwide umbrella, called the United Network for Organ Sharing (UNOS). UNOS is a private, nonprofit organization that matches available organ donors with those awaiting transplantation. UNOS is under contract with the U.S. Department of Health and Human Services to maintain the nation’s organ transplant waiting list. UNOS guarantees that all persons who need a transplant have an equal opportunity to receive their organs, regardless of age, gender, race, social status, and so on.

There are 11 geographic UNOS regions in the country. These regions play a role in organ allocation, as organs are offered to sick patients within the same region in which they are donated before being offered to other parts of the country.

There are 58 organ procurement organizations (OPOs) in the United States. These are private, nonprofit organizations that coordinate the organ procurement in a designated service area, which may cover all or only part of a state. The OPO evaluates potential donors, discusses donation with potential donor family members, arranges for the surgical removal of donated organs, and arranges for the distribution of the organs according to national organsharing policies.

The allocation of an available donor heart is determined by a number of strict established criteria, specifically

• Blood type (A, B, AB, O types) compatibility

• Severity of illness (acuity) or medical urgency of the recipient, according to UNOS criteria (“UNOS status”)

• Body size compatibility

• The length of time a person has been on the waiting list

All this information is then entered into the UNOS computerized waiting list. When a heart becomes available, it is given to the best possible match, based on these strict established criteria. The race and gender of the donor have no bearing on the match.

During your transplant evaluation process, a test is performed to determine your blood type. This plays a role in determining a “donor match,” or from which donors you can accept a heart (Table 6). In general, candidates on the list receive an identically matched blood group heart (as determined by ABO blood typing), regardless of the Rh factor (rhesus factor, the + or − sign that occurs after the blood type). Fortunately, matching the Rh factor does not seem to have any significant influence of the outcome of the transplant or the likelihood of rejection. Because some blood groups are more common than others, the amount of time on the waiting list may be influenced by your blood type as well as the blood type of any available donors.