Biological sealants and knitted Dacron conduits: comparison of collagen and fibrin glue pretreatments in circulatory models.

To assess the healing characteristics of knitted Dacron conduits sealed with fibrin glue, collagen cross-linked with glutaraldehyde, and collagen cross-linked with formaldehyde, composite conduits, each constructed from two of the three test materials, were implanted in the pulmonary and systemic circulations of sheep and dogs for 3 and 6 months. Relative rates and morphologies of sealant resorption and other histological findings were predicted by a previous study involving subcutaneous implantation of the same graft materials in the rat. In particular, both studies revealed that delayed resorption of collagen cross-linked with glutaraldehyde and collagen cross-linked with formaldehyde resulted in lack of adhesion between inner capsule and conduit, thereby causing focal hemorrhagic dissection in the circulatory implants. There were no important qualitative or quantitative differences in healing between sheep and dogs or in pulmonary versus systemic location of the conduit. Rendering an animal cyanotic by placing a pulmonary arterial-left atrial shunt or by increasing or decreasing the intraconduit systolic pressure did not obviously affect healing. The results emphasize that the biological consequences of sealed grafts are strongly dependent on the sealant material. Porosity control of knitted Dacron with biological sealants that undergo minimal or delayed resorption may lead to poor tissue adhesion and resultant complications.