Poly-lactic-acid coating for endovascular stents. Preliminary results in canine experimental arteriovenous fistulae.
OBJECTIVE
The authors evaluate polylactic-acid (PLA) as a coating of vascular endoprostheses in the treatment of experimental arteriovenous fistulae (AVF) in a canine model.


METHODS
Bilateral carotid external jugular AVF were created in five adult dogs. Seven PLA-coated nitinol stents were placed using a transfemoral approach to cover five AVF. Contralateral controls remained untreated. Angiography was performed immediately after stent placement and at weeks 1 and 3, as well as at months 3, 6, and 9. All grafts were removed and underwent histologic examination.


RESULTS
In two cases, the occlusion of the AVF was successful, but misplacement of stents occurred in three cases, which showed occlusion of the parent vessel between week 1 and month 3. One thrombembolic stent occlusion was evident during angiographic control. One vessel occlusion was disclosed distal to the stented arterial segment. Histologic examination revealed a mild inflammatory reaction with the presence of macrophages. However, there was no foreign-body reaction of fragmentation of the vessel wall.


CONCLUSIONS
Histologic examination revealed good biocompatibility of PLA, which is a well-known biodegradable material. Elastic mismatch of the nonelastic coating and the self-expandable nitinol stent led to misplacement, whereas vessel occlusion was probably due to PLA filaments fraying into the vessel lumen. Using a different textile structure, PLA might be a material suitable for coated stents.
Schellhammer
F
F
Department of Neuroradiology, University of Freiburg, Germany.
Berlis
A
A
Bloss
H
H
Pagenstecher
A
A
Schumacher
M
M
D000497:Alloys; D000818:Animals; D001164:Arteriovenous Fistula / Q000000981:diagnostic imaging / Q000628:therapy*; D001672:Biocompatible Materials; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D004285:Dogs; D007601:Jugular Veins / Q000000981:diagnostic imaging / Q000473:pathology; D019344:Lactic Acid; D011091:Polyesters; D011108:Polymers; D011859:Radiography; D015607:Stents / Q000009:adverse effects; D013499:Surface Properties
D000497:Alloys; D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; C013616:nitinol; D019344:Lactic Acid; C033616:poly(lactide)