Nosocomial graft fragmentation and healing response of an ePTFE angioaccess graft

This investigation was directed toward the tissue reaction and wound healing response of an ePTFE prosthesis implanted in a human subject as an arteriovenous fistulae for over 7 years. Due to the frequent puncture of the prosthesis for hemodialysis access, the pattern of healing is markedly different from that normally observed in ePTFE grafts in humans. The ePTFE graft material of the AV fistula was completely incorporated in fibrous tissue with prominent pseudointima formation (inner capsule), fibrous tissue within the graft and a well-adhered periadventitial layer (outer capsule). In the portion of the graft most frequently punctured, the wall of the graft was composed mainly of fibrous tissue containing dissociated fragments of ePTFE. Biochemical analysis of the fibrous tissue across the wall of the graft revealed that it contained types I, III, and V collagen, with type I greater than III greater than V. The type V collagen was present in largest percentage at the luminal surface and in decreasing percentage in the ePTFE material and outer capsule. This analysis suggests that collagen type deposition in this prosthesis occurs in a manner similar to a normal healing wound, except for the unusual pattern of type V collagen deposition, which may be an adaptive variation of the healing response.