['Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome causes a marked immunologic sensitization that may complicate future heart transplantation. Treatment of the allograft tissue before implantation may prevent this sensitization. The purpose of this study was to assess the anti-human leukocyte antigen antibody response to glutaraldehyde-treated allograft tissue used in the repair of hypoplastic left heart syndrome.', 'Since June 2005, the University of Alberta has subjected allograft vascular tissue used in the Norwood procedure to glutaraldehyde treatment. An observational study was designed to assess whether glutaraldehyde treatment of the allograft tissue affected subsequent panel reactive antibody after patch implantation. Panel reactive antibodies for class I (human leukocyte antigen-A, B, C) and class II (human leukocyte antigen-DR, DQ) antibodies were measured 4 months postoperatively using flow cytometry.', 'Fourteen patients underwent a Norwood procedure using glutaraldehyde-treated allograft tissue. Historical controls consisted of 12 patients who underwent a Norwood procedure using untreated allograft tissue. At 4 months, infants who had received glutaraldehyde-treated allograft tissue had lower class I panel reactive antibody (7.3% +/- 17.4% [median, 0%] vs 61.9% [median, 73%] +/- 39.9%; P = .0005) and class II panel reactive antibody (6.1% [median, 0%] +/- 22.7% vs 49.3% [median, 63%] +/- 41.9%, P = .001) compared with the historical controls.'] Does glutaraldehyde treatment of allograft tissue decrease allosensitization after the Norwood procedure?