title: Spatial and temporal changes in compliance following implantation of bioresorbable vascular grafts.
abstract: Compliance matching between the host vessel and vascular grafts used for small-diameter arterial replacements is thought to be important for long-term patency. However, currently available grafts elicit fibroplastic reactions, resulting in decreasing compliance with time after implantation. Bioresorbable prostheses elicit ingrowth of myofibroblasts containing abundant contractile elements. This led us to investigate whether compliance of implanted bioresorbable prostheses decreased as a function of time and if the kinetics of change correlated with the progression of tissue ingrowth. Woven polyglactin 910 prostheses (10 mm x 4 mm i.d.) were implanted into adult NZW rabbit infrarenal aortas and replicates were harvested serially through 8 months. Control grafts were implanted, and immediately resected. Dynamic compliance was measured at 1-mm axial increments along each explant using a pulse duplicator apparatus which exposed the harvested samples to realistic pulsatile hemodynamics. Compliance was calculated for proximal, mid, and distal segments of each graft and averaged at each time point by grouping into control (zero time, n = 3), early (1-4 weeks, n = 13), and late (6-36 weeks, n = 9) explant periods. At late explant periods both proximal and distal compliance were significantly greater than mid graft compliance (p < .02 and p < .03, respectively). There was a significant increase in proximal compliance between early and late explant times (p < .01). Measured increases in mid and distal segment compliance over time did not reach statistical significance. Myofibroblast laden tissue ingrowth into the inner capsule followed macrophage phagocytosis and was nearly complete prior to the time that an increase in compliance was demonstrated. Thus since the major histologic episodes precede the change in compliance, these are not likely initiated by this biomechanical change. We hypothesize the graft resorption coupled with the ingrowth of more compliant tissue likely leads to the increased compliance of the graft material.
authors.affiliation: Loyola University Medical Center, Department of Surgery, Maywood, Illinois 60153.
authors.forename: H P
authors.initials: HP
authors.lastname: Greisler
authors.forename: K A
authors.initials: KA
authors.lastname: Joyce
authors.forename: D U
authors.initials: DU
authors.lastname: Kim
authors.forename: S M
authors.initials: SM
authors.lastname: Pham
authors.forename: S A
authors.initials: SA
authors.lastname: Berceli
authors.forename: H S
authors.initials: HS
authors.lastname: Borovetz
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000166:cytology / Q000601:surgery* / Q000648:ultrastructure; D001672:Biocompatible Materials; D001807:Blood Vessel Prosthesis; D005260:Female; D008854:Microscopy, Electron; D011098:Polyglactin 910; D011817:Rabbits; D013314:Stress, Mechanical
chemical_list: D001672:Biocompatible Materials; D011098:Polyglactin 910