title: Environmental stress cracking performance of polyether and PDMS-based polyurethanes in an in vitro oxidation model.
abstract: Environmental stress cracking (ESC) was replicated in vitro on Optim™ (OPT) insulation, a polydimethylsiloxane-based polyurethane utilized clinically in cardiac leads, using a Zhao-type oxidation model. OPT performance was compared to that of two industry standard polyether urethanes: Pellethane®80A (P80A), and Pellethane®55D (P55D). Clinically relevant specimen configurations and strain states were utilized: low-voltage cardiac lead segments were held in a U-shape by placing them inside of vials. To study whether aging conditions impacted ESC formation, half of the samples were subjected to a pretreatment in human plasma for 7 days at 37°C; all samples were then aged in oxidative solutions containing 0.9% NaCl, 20% H2O2, and either 0 or 0.1M CoCl2, with or without glass wool for 72 days at 37°C. Visual and SEM inspection revealed significant surface cracking consistent with ESC on all P80A and P55D samples. Sixteen of twenty P80A and 10/20 P55D samples also exhibited breaches. Seven of 20 OPT samples exhibited shallow surface cracking consistent with ESC. ATR-FTIR confirmed surface changes consistent with oxidation for all materials. The number average molecular weight decreased an average of 31% for OPT, 86% for P80A, and 56% for P55D samples. OPT outperformed P80A and P55D in this Zhao-type in vitro ESC model. An aging solution of 0.9% NaCl, 20% H2O2, and 0.1M CoCl2, with glass wool provided the best combination of ESC replication and ease of use. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1544-1558, 2017.
authors.affiliation: St. Jude Medical, St. Paul, MN.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Gallagher
authors.affiliation: St. Jude Medical, Rogers, MN.
authors.forename: Ajay
authors.initials: A
authors.lastname: Padsalgikar
authors.affiliation: St. Jude Medical, Sylmar, CA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Tkatchouk
authors.affiliation: St. Jude Medical, Sylmar, CA.
authors.forename: Chris
authors.initials: C
authors.lastname: Jenney
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA.
authors.forename: Ciprian
authors.initials: C
authors.lastname: Iacob
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA.
authors.forename: James
authors.initials: J
authors.lastname: Runt
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D011140:Polyurethanes / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D004129:Dimethylpolysiloxanes; D011140:Polyurethanes; D012965:Sodium Chloride; C013830:baysilon; D006861:Hydrogen Peroxide
keywords: environmental stress cracking; hydrogen peroxide; in vitro; polydimethylsiloxane-based polyurethane; polyether urethane