title: Cryopreserved and fresh antibiotic-sterilized valved aortic homograft conduits in a long-term sheep model. Hemodynamic, angiographic, and histologic comparisons.
abstract: There is a paucity of clinical and experimental data regarding the fate of cryopreserved valve aortic homografts. Fifteen lambs (mean age 4 months) underwent insertion of a valved aortic homograft between the right ventricle and pulmonary artery. In eight animals, the homografts were treated with antibiotics for 48 hours followed by up to 4 days of 4 degrees C storage (group A). In the other seven animals, the homografts were treated with antibiotics and cryopreserved at -196 degrees C (group B). The 12 long-term survivors were catheterized at 6 weeks and 4 months after implantation, at which time three animals from each group were killed. The remaining six animals were catheterized and killed at 9 months. There was no significant difference in transconduit gradient (p = 0.67) or resistance indexed to weight (p = 0.81) between groups A and B. The mean increase in transconduit gradient for both groups between catheterization at 6 weeks and 4 months was 73%, and weight increased by 51%. Histologic analysis focusing particularly on valve leaflet architecture and changes in the aortic wall revealed greater differences between individual animals and according to duration of implantation than differences between groups A and B. However, focal intracuspal thrombus of unknown significance was seen only in animals from group B. Although conduit valve leaflets generally remained free of calcification, calcification was prominent within the conduit wall of all animals. In conclusion, cryopreservation does not appear to adversely affect leaflet integrity and conduit function in this accelerated animal model relative to fresh homografts. This is in contrast to past clinical experience with homografts treated by freeze-drying and irradiation.
authors.affiliation: Department of Cardiac Surgery, Children's Hospital, Boston, Mass. 02115.
authors.forename: R A
authors.initials: RA
authors.lastname: Jonas
authors.forename: G
authors.initials: G
authors.lastname: Ziemer
authors.forename: L
authors.initials: L
authors.lastname: Britton
authors.forename: L C
authors.initials: LC
authors.lastname: Armiger
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001021:Aortic Valve / Q000637:transplantation*; D005260:Female; D005615:Freezing; D006085:Graft Survival; D006350:Heart Valve Prosthesis; D006352:Heart Ventricles / Q000601:surgery; D008297:Male; D011651:Pulmonary Artery / Q000601:surgery; D012756:Sheep; D014021:Tissue Preservation; D014184:Transplantation, Homologous
chemical_list: D000900:Anti-Bacterial Agents