Comparison of small intestinal submucosa-covered and noncovered nitinol stents in sheep iliac arteries: a pilot study.
OBJECTIVE
To compare the biocompatibility and performance of nitinol endografts covered externally or internally with small intestinal submucosa (SIS) with bare nitinol stents in medium-sized arteries.


METHODS
Eighteen nitinol Zilver stents were used: six externally SIS-covered endografts (ECEs), six internally SIS-covered endografts (ICEs), and six bare stents (BSs). Devices were implanted in the balloon-injured external iliac arteries (EIAs) of nine female sheep via carotid approach. Arteriograms were obtained before and after implantation and before animal sacrifice at 1, 3, and 6 months. Histologic studies of explanted specimens were performed.


RESULTS
Implantation of all BSs, ECEs, and ICEs was successful, but slight luminal narrowing of 19% +/- 5.3% (range, 12%-28%) was seen in ICEs on postimplantation angiograms. At sacrifice, all six BSs and ECEs were patent, with BSs showing a mean angiographic luminal narrowing of 8.4% +/- 7.2% (range, 0%-18%) and ECEs showing a mean angiographic luminal narrowing of 16% +/- 7.5% (range, 6.5%-26%) as a result of neointimal hyperplasia. Four ICEs showed luminal narrowing of 21% +/- 17% (range, 0%-35%) as a result of marked neointimal hyperplasia and two were occluded, one at 3 months and the other at 6 months. ECEs and BSs showed approximately 80% lumen endothelialization at 1 month, which increased to 100% at 3 and 6 months. ICEs did not show complete endothelialization.


CONCLUSIONS
The BS had the least vessel wall reaction. ECEs exhibited early endothelialization with early mild to moderate wall reaction decreasing at the late study stages. ICEs showed extensive wall reaction, possibly as a result of technical problems with SIS attachment.
Toyota
Naoyuki
N
Dotter Interventional Institute, Oregon Health Sciences University, L342, 3181 SW Sam Jackson Park Rd., Portland, OR 87201, USA.
Pavcnik
Dusan
D
VanAlstine
William
W
Uchida
Barry T
BT
Timmermans
Hans A
HA
Yin
Qiang
Q
Kaufman
John A
JA
Keller
Frederick S
FS
Ito
Katsuhide
K
Rösch
Josef
J
D000497:Alloys / Q000627:therapeutic use*; D000818:Animals; D019917:Blood Vessel Prosthesis Implantation; D020099:Coated Materials, Biocompatible / Q000627:therapeutic use; D004869:Equipment Safety; D005260:Female; D005500:Follow-Up Studies; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000637:transplantation*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000601:surgery*; D007421:Intestine, Small / Q000098:blood supply*; D008214:Lymphocytes / Q000097:blood; D023421:Models, Animal; D010865:Pilot Projects; D011474:Prosthesis Design; D011859:Radiography; D012756:Sheep; D015607:Stents; D013997:Time Factors; D016896:Treatment Outcome
D000497:Alloys; D020099:Coated Materials, Biocompatible; C013616:nitinol