title: Bench and initial preclinical results of a novel 8 mm diameter double opposed helical biodegradable stent.
abstract: BACKGROUND
  Metallic endovascular stents are utilized off-label in congenital heart disease. Biodegradable stents (BDS) offer potential advantages in a growing child. We have previously reported double opposed helical (DH) BDS up to 6 mm diameter (DH-6). The objectives are to investigate the bench characteristics of larger 8 mm diameter BDS (DH-8) manufactured with increasing strut thicknesses and the inflammatory profile in a porcine model.
  
  
  METHODS
  DH-8 were manufactured with strut thicknesses 0.10, 0.12, and 0.18 mm and mechanical testing performed. Stents were deployed into the infrarenal descending aorta (DAO) of nine minipigs. At insertion (nonsurvival = 2), 1 week (n = 2), 1 month (n = 2), and 9 months (n = 3) follow-up angiography, intravascular ultrasound and histopathology were performed.
  
  
  RESULTS
  There was superior recoil and collapse pressure with increasing strut thickness, with 0.18 mm having 1.0% elastic recoil and collapse pressure 0.75 Atmospheres. There was good wall apposition at insertion with 5 BDS (4 DH-8 and 1 DH-6) but suboptimal in 4 as the minipigs infrarenal DAO were >8 mm (deployed at iliac bifurcation). Structural integrity was maintained in 8 BDS with 1 DH-8 collapsed at 9 months, secondary to strut damage at insertion. No thrombosis was seen. There was mild inflammation and neointimal proliferation at 1 week and 1 month, but a moderate inflammatory response at 9 months.
  
  
  CONCLUSIONS
  DH-8 with increased strut thickness had acceptable mechanical properties at the cost of an increased inflammatory response. Miniaturization to improve delivery and further investigation on the long-term inflammatory profile of thicker struts, including through degradation, is needed. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Division of Cardiology, Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Carrie E
authors.initials: CE
authors.lastname: Herbert
authors.affiliation: Division of Cardiology, Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Surendranath
authors.initials: S
authors.lastname: Veeram Reddy
authors.affiliation: Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Tré R
authors.initials: TR
authors.lastname: Welch
authors.affiliation: Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Pathology, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: James A
authors.initials: JA
authors.lastname: Richardson
authors.affiliation: Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Forbess
authors.affiliation: Division of Cardiology, Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas.
authors.forename: Alan W
authors.initials: AW
authors.lastname: Nugent
mesh_terms: D000792:Angiography; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000601:surgery*; D001018:Aortic Diseases / Q000175:diagnosis / Q000601:surgery*; D004195:Disease Models, Animal; D054855:Drug-Eluting Stents; D057510:Endovascular Procedures / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D011474:Prosthesis Design; D013552:Swine; D013556:Swine, Miniature; D041623:Tomography, Optical Coherence; D018084:Ultrasonography, Interventional
keywords: BIOD; SBIO; SDES; bioabsorbable; bioabsorbable devices/polymers; stent; stent design/structure/coatings