STP859: In Vivo Degradation of a Polyurethane: Preclinical Studies

    Parins, DJ
    Director of Research, Angiomedics, Inc., Minneapolis, MN

    McCoy, KD
    Scanning electron microscopist, lead scientist, and microbiologist, Cardiac Pacemakers, St. Paul, MN

    Horvath, N
    Scanning electron microscopist, lead scientist, and microbiologist, Cardiac Pacemakers, St. Paul, MN

    Olson, RW
    Scanning electron microscopist, lead scientist, and microbiologist, Cardiac Pacemakers, St. Paul, MN

    Pages: 18    Published: Jan 1985


    Abstract

    In vivo investigation of a polyether polyurethane for possible use as pacing lead insulation material revealed surface degradation in the form of numerous cracks. The cracking phenomenon appeared to be stress related. Cracks were observed after three months implant time in rats and affected greater surface area with increasing implant time.

    Toxicological investigation of the host animals revealed no adverse effects attributable to the polymer cracking phenomenon.

    Examination by scanning electron microscopy revealed cracking that raised concerns about the integrity of thin-walled pacing leads. Ambient controls and in vitro specimens did not develop surface cracks. Surface cracking was independent of weight averaged molecular weight (Mw) and was observed on all tested samples, the Mw ranged from 255 000 through 636 000. No significant change in Mw after implant could be detected.

    Surface degradation of this polyurethane was reproducible in controlled animal studies.

    Keywords:

    pacing leads, polyether polyurethane, scanning electron microscopy, surface cracking, failure mechanisms, stress (materials), implant materials


    Paper ID: STP33261S

    Committee/Subcommittee: F04.48

    DOI: 10.1520/STP33261S


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