title: Iliac anastomotic stenting with a biodegradable poly-L-lactide stent: a preliminary study after 1 and 6 weeks.
abstract: OBJECTIVE
  To assess the technical feasibility, thrombogenicity, and biocompatibility of a new biodegradable poly-L-lactic acid (PLLA) anastomotic stent.
  
  
  METHODS
  A polytetrafluoroethylene bifurcated graft was implanted in 17 pigs through a midline abdominal incision. After transverse graft incision, 17 316L stainless steel stents and 17 PLLA stents were randomly implanted at both iliac anastomotic sites and deployed with a 6-mm balloon under direct vision without angiography. Intended follow-up was 1 week in 6 pigs receiving oral acetylsalicylic acid (ASA) and in 7 pigs receiving ASA/clopidogrel; 4 pigs receiving ASA/clopidogrel were followed for 6 weeks. At the end of the study, the segments containing the stents were surgically explanted and processed for histology to measure the mean luminal diameter, intimal thickness, and the vascular injury and inflammation scores.
  
  
  RESULTS
  Initial technical success of stent placement was achieved in all animals without rupture of the suture. Two pigs died (unrelated to the stent) at 3 days after operation (1 in groups A and B). At 1 week, all PLLA stents showed thrombotic occlusion with the use of ASA alone. In contrast, all PLLA stents remained patent with concurrent administration of ASA/clopidogrel. All metal stents were patent regardless of the antiplatelet regimen. The mean luminal diameter of patent PLLA stents (4.13+/-0.17 mm) was comparable to metal stents (4.27+/-0.35 mm, p=0.78) at 1 week, but significantly diminished at 6 weeks (3.21+/-0.44 versus 4.19+/-0.18 mm, p=0.005). Histological analysis showed no signs of excessive recoil. PLLA stents induced a higher inflammation score (1.79+/-0.56) and more intimal hyperplasia (0.34+/-0.11 mm) compared to metal stents [1.27+/-0.44 mm (p<0.001) and 0.18+/-0.04 mm (p=0.006), respectively] at 6 weeks. Vascular injury was comparable between PLLA and metal stents.
  
  
  CONCLUSIONS
  Biodegradable PLLA stents showed higher thrombogenicity and reduced patency compared to metal stents during early follow-up. Although ASA and clopidogrel prevented thrombotic occlusion, the increased inflammatory response and neointima formation remain major concerns of PLLA stents. A solution to this problem might be the incorporation of anti-inflammatory drugs into the PLLA stent.
authors.affiliation: Department of Surgery, University of Rostock, Germany. carsten.buenger@medizin.uni-rostock.de
authors.forename: Carsten Michael
authors.initials: CM
authors.lastname: Bünger
authors.forename: Niels
authors.initials: N
authors.lastname: Grabow
authors.forename: Katrin
authors.initials: K
authors.lastname: Sternberg
authors.forename: Lisa
authors.initials: L
authors.lastname: Ketner
authors.forename: Christina
authors.initials: C
authors.lastname: Kröger
authors.forename: Björn
authors.initials: B
authors.lastname: Lorenzen
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Hauenstein
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Schmitz
authors.forename: Hans Jürgen
authors.initials: HJ
authors.lastname: Kreutzer
authors.forename: Daniel
authors.initials: D
authors.lastname: Lootz
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Ince
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Nienaber
authors.forename: Ernst
authors.initials: E
authors.lastname: Klar
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schareck
mesh_terms: D020341:Absorbable Implants; D000714:Anastomosis, Surgical / Q000295:instrumentation*; D000818:Animals; D001167:Arteritis / Q000473:pathology / Q000517:prevention & control; D001241:Aspirin / Q000494:pharmacology; D000077144:Clopidogrel; D005240:Feasibility Studies; D005260:Female; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology; D017078:Laser-Doppler Flowmetry; D010865:Pilot Projects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011091:Polyesters; D015607:Stents; D013552:Swine; D013927:Thrombosis / Q000188:drug therapy / Q000473:pathology / Q000517:prevention & control; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000494:pharmacology; D017539:Tunica Intima / Q000473:pathology; D014463:Ultrasonography
chemical_list: D010975:Platelet Aggregation Inhibitors; D011091:Polyesters; C033616:poly(lactide); D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin