Df. Kallmes et al., Dr. Gary J. Becker Young Investigator Award: Comparison of small-diameter type 1 collagen stent-grafts and PTFE stent-grafts in a canine model - Workin progress, J VAS INT R, 12(10), 2001, pp. 1127-1133
PURPOSE: To report an in-progress experiment in a canine model in which two
types of small-diameter stent-grafts-one constructed of polytetrafluoroeth
ylene (PTFE) and the other of a new, type I collagen material-were compared
regarding vessel patency, intimal hyperplasia formation, and tissue reacti
MATERIALS AND 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 ballo
on-expandable stainless-steel stents wrapped with either PTFE or a new type
1 collagen graft. Stent-grafts were placed in deep femoral arteries bilate
rally (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 bas
ed on angiographic findings as well as thickness and area of neointimal hyp
erplasia were compared at each time point and compared with use of the Stud
ent 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 f
ive patent collagen stent-grafts. All five patent PTFE stent-grafts showed
demonstrable in-stent stenosis (10%-60%), indicating a trend toward improve
d patency in collagen stent-grafts versus PTFE stent-grafts (P = .07). Neoi
ntimal hyperplasia was absent at 2 weeks in the collagen stent-grafts. Neoi
ntimal thickness increased to a maximum of 360 mum at 12 weeks in the colla
gen stent-grafts. For PTFE stent-grafts, neointimal hyperplasia was present
in all samples and reached a maximum of 770 mum at 12 weeks (P = .03).
CONCLUSIONS: Even in small-diameter vessels, type 1 collagen stent-grafts d
emonstrate excellent patency rates and favorable histologic findings. The t
ype I collagen stent-graft technology merits further developmental efforts
in preclinical models.