Dr. Gary J. Becker young investigator award: comparison of small-diameter type 1 collagen stent-grafts and PTFE stent-grafts in a canine model--work in progress.
OBJECTIVE
To report an in-progress experiment in a canine model in which two types of small-diameter stent-grafts-one constructed of polytetrafluoroethylene (PTFE) and the other of a new, type 1 collagen material-were compared regarding vessel patency, intimal hyperplasia formation, and tissue reaction.


METHODS
Six mongrel dogs weighing 30-35 kg were used. Stent-grafts of 4-mm diameter and 20-mm length were constructed with use of balloon-expandable stainless-steel stents wrapped with either PTFE or a new type 1 collagen graft. Stent-grafts were placed in deep femoral arteries bilaterally (PTFE on one side, collagen on the other). Animals were followed for 2 weeks (n = 2), 6 weeks (n = 2), or 12 weeks (n = 2). Percent stenosis based on angiographic findings as well as thickness and area of neointimal hyperplasia were compared at each time point and compared with use of the Student t test.


RESULTS
All devices were patent in the immediate postimplantation period. Five of six collagen stent-grafts and five of six PTFE implants were patent at follow-up. In-stent stenosis was undetectable angiographically in all five patent collagen stent-grafts. All five patent PTFE stent-grafts showed demonstrable in-stent stenosis (10%-60%), indicating a trend toward improved patency in collagen stent-grafts versus PTFE stent-grafts (P = .07). Neointimal hyperplasia was absent at 2 weeks in the collagen stent-grafts. Neointimal thickness increased to a maximum of 360 microm at 12 weeks in the collagen stent-grafts. For PTFE stent-grafts, neointimal hyperplasia was present in all samples and reached a maximum of 770 microm at 12 weeks (P = .03).


CONCLUSIONS
Even in small-diameter vessels, type 1 collagen stent-grafts demonstrate excellent patency rates and favorable histologic findings. The type 1 collagen stent-graft technology merits further developmental efforts in preclinical models.
Kallmes
D F
DF
Department of Radiology, University of Virginia, Charlottesville, Virginia, USA. dfk3b@virginia.edu
Lin
H B
HB
Fujiwara
N H
NH
Short
J G
JG
Hagspiel
K D
KD
Li
S T
ST
Matsumoto
A H
AH
D000818:Animals; D001363:Awards and Prizes; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects* / Q000379:methods; D024042:Collagen Type I / Q000009:adverse effects* / Q000737:chemistry / Q000648:ultrastructure; D004285:Dogs; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006965:Hyperplasia / Q000209:etiology; D023421:Models, Animal; D010865:Pilot Projects; D011138:Polytetrafluoroethylene / Q000009:adverse effects* / Q000737:chemistry; D011474:Prosthesis Design; D011859:Radiography; D015607:Stents / Q000009:adverse effects; D017539:Tunica Intima / Q000473:pathology*; D014654:Vascular Patency
D024042:Collagen Type I; D011138:Polytetrafluoroethylene