SHOULD THE AORTIC-VALVE HOMOGRAFT BE RECRYOPRESERVED

Background. The number of homograft donors is limited and the once-tha wed homograft may be unsuitable for the recipient and obliged to be wa sted. The purpose of this study was to investigate the possibility of recryopreserving and using the once-thawed homograft for another patie nt. Methods. Canine aortic valve leaflets were frozen to -80 degrees C by a programmed freezer, stored in liquid nitrogen, and thawed after 1 week. A subgroup of leaflets was left at 4 degrees C for 15 minutes, re-cryopreserved, and thawed after 1 week. Pathologic and flow cytome tric evaluations were performed. Results. After thawing, by pathology, alignment of the fibers was acceptably maintained but the membrane an d cytoplasm of the fibroblast were damaged. These findings were not si gnificantly aggravated even after rethawing. By flow cytometry, fibrob last viability was 90.7% +/- 1.7% immediately after thawing, 87.6% +/- 1.0% after thawing for 15 minutes at 4 degrees C, 63.7% +/- 2.7% duri ng refreezing at 0 degrees C, and 39.4% +/- 4.3% after rethawing. Conc lusions. From the standpoint of fibroblast viability, it is not possib le to recryopreserve the once-cryopreserved and thawed aortic valve ho mograft. (C) 1998 by The Society of Thoracic Surgeons.