title: The biostability of cardiac lead insulation materials as assessed from long-term human implants.
abstract: Accelerated in vitro biostability studies are useful for making relativistic comparisons between materials. However, no in vitro study can completely replicate the complex biochemical and biomechanical environment that a material experiences in the human body. To overcome this limitation, three insulation materials [Optim™ insulation (OPT), Pellethane® 55D (P55D), and silicone elastomer] from cardiac leads that were clinically implanted for up to five years were characterized using visual inspection, SEM, ATR-FTIR, GPC, and tensile testing. Surface cracking was not observed in OPT or silicone samples. Shallow cracking was observed in 17/41 (41%) explanted P55D samples. ATR-FTIR indicated minor surface oxidation in some OPT and P55D samples. OPT molecular weight decreased modestly (∼20%) at 2-3 years before stabilizing at 4-5 years. OPT tensile strength decreased modestly (∼25%) at 2-3 years before stabilizing at 4-5 years. OPT elongation at 4-5 years was unchanged from controls. P55D had no significant changes in molecular weight or tensile properties. Overall, results for OPT and P55D were consistent with and limited to cosmetic surface oxidation. Silicone demonstrated excellent biostability with no identifiable degradation. This study of explanted cardiac leads revealed that OPT, P55D, and silicone elastomer demonstrate similar and excellent biostability through five years of implantation in human patients.
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, Ohio.
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Wilkoff
authors.affiliation: Department of Cardiology, Johns Hopkins University, Baltimore, Maryland.
authors.forename: John
authors.initials: J
authors.lastname: Rickard
authors.affiliation: Implantable Electronic Systems Division, St. Jude Medical, Sylmar, California.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Tkatchouk
authors.affiliation: Implantable Electronic Systems Division, St. Jude Medical, Rogers, Minnesota.
authors.forename: Ajay D
authors.initials: AD
authors.lastname: Padsalgikar
authors.affiliation: Implantable Electronic Systems Division, St. Jude Medical, St. Paul, Minnesota.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Gallagher
authors.affiliation: Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania.
authors.forename: James
authors.initials: J
authors.lastname: Runt
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D007854:Lead / Q000737:chemistry*; D008297:Male; D010084:Oxidation-Reduction; D011140:Polyurethanes / Q000737:chemistry*; D012826:Silicone Elastomers / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D011140:Polyurethanes; D012826:Silicone Elastomers; C059617:pellethane 2363-55D; D007854:Lead
keywords: Optim™ insulation; biostability; cardiac leads; clinical; in vivo