Time-related alterations in shape, position, and structure of self-expanding, modular aortic stent-grafts: A 4-year single-center follow-up

Purpose: To report the nature and ramifications of structural and positiona l changes over time in tube and modular bifurcated aortic stent-grafts. Methods: Two hundred ninety-one patients received endovascular aortic graft s (primarily Stentor/Vanguard) between August 1994 and August 1998. Follow- up surveillance (clinical and laboratory examination, biplanar noncontrast radiography, and contrast-enhanced computed tomography) has been maintained on all patients for 4 years. Changes in the configuration and position of endografts have been noted and their sequelae charted. Results: Three types of endograft shape changes have been documented: mild - slight distortions visible on plain radiographs (n = 90, 31.0%), signific ant - angulations reaching 60 degrees to 90 degrees (n = 65, 22.3%), and se vere - angulations greater than or equal to 90 degrees (n = 10, 3.4%). Chan ges in position never gave rise to late migration at the proximal attachmen t site, whereas at the distal ends, the en dog raft easily retracted from t he iliac arteries (n = 8). Structural alterations (rupture of the stent fra me, sutures, or fabric, and total graft disintegration) were more common in the original Stenter model. Shape, position, and structural alterations we re mutually dependent and led to secondary endoleaks (n = 26) and graft lim b thrombosis (n = 37). Late surgical conversion was necessary in 3 (1.0%) p atients. Conclusions: Tortuosity of the native vessels is a source of complication i n long-term follow-up just as it is during implantation. Given the late app earance of complications in this patient cohort, it would seem th at the du rability of an endograft cannot be evaluated with < 3 years of follow-up.