A novel method for ABO-incompatible heart transplantation

Background: Since 1996, ABO-incompatible heart transplantation has been undertaken by performing whole-body plasma exchange to remove isohemagglutinins using the cardiopulmonary bypass (CPB) circuit at the time of transplantation. This requires large volumes of donated blood and blood products, causes hemodynamic instability during the exchange transfusion, and limits practical use to small children. We sought to determine the efficacy of anti-A/B immunoadsorption within the CPB circuit on removal of isohemagglutinins in an ex vivo setting before its use clinically.

Methods: An anti-A/B immunoadsorption column was placed into a CPB circuit mimicking a typical ABO-incompatible transplant patient, which had been primed with type O whole human blood. Samples were taken for determination of isohemagglutinin titers following each plasma volume pass through the anti-A/B immunoadsorption column.

Results: There was a linear decrease of at least 1 dilution seen in both anti-A and anti-B IgG and IgM antibodies with each plasma volume pass through the column. This predictable removal allowed the formulation of selection criteria for ABO-incompatible heart transplantation given the reciprocal of titer and patient weight. This degree of predictability allowed us to use it successfully in the clinical setting, reducing antibodies to an undetectable level during ABO-incompatible heart transplantation.

Conclusions: The incorporation of an anti-A/B immunoadsorption column into the extracorporeal circuit reduces allogeneic blood product requirement for ABO-incompatible heart transplantation, while providing efficacious removal of anti-A and anti-B isohemagglutinins. This can be undertaken within the time period of CPB before graft reperfusion and expands the potential recipient pool to larger patients with higher isohemagglutinin titers.