Longitudinal ruptures of polyester knitted vascular prostheses

Aim: The purpose of the study was the characterization of a type of rupture occurring on warp-knitted polyester vascular prostheses. Materials and Methods: We studied 20 cases of warp-knitted polyester vascul ar prostheses that were explanted from humans that showed a longitudinal ru pture as a part of a collaborative retrieval program. All the prostheses we re immediately fixed in a 10% formaldehyde solution after their explantatio n in the operating room. The clinical data of these cases were recorded. Th e explants were photographed, washed to eliminate the surrounding tissues, and photographed again. The ruptures were characterized with macroscopic ex amination, optical stereomicroscopy, and scanning electron microscopy. Results: The mean duration of implantation of the prostheses was 16.0 +/- 3 .3 years (range, 9-20.7 years). The prostheses were Cooley Double Velour (n = 15) and Microvel Double Velour (n = 5). There were 16 aortobifemoral byp ass grafts, 1 aorto-biiliac, 1 aorto-aortic, 1 iliofemoral, and 1 axillobif emoral. The longitudinal ruptures occurred on two specific parts of the pro stheses: the guide line (6 cases) and the remeshing line(ll cases). In thre e cases both lines were affected. Scanning electron microscopy showed major degradation of the trilobar filaments of the velour and gradual ruptures o f the flat filaments of the remeshing and guide lines. Conclusions: In this study, we have identified a specific mechanism of late (9-20 years) longitudinal rupture of knitted polyester prostheses consisti ng of degradation of the polyester filaments along the remeshing and guide lines that run the length of the graft.