TISSUE-REACTIONS TO BACTERIA-CHALLENGED IMPLANTABLE LEADS WITH ENHANCED INFECTION-RESISTANCE

Tissue reactions to implantable pacemaker leads were investigated in a n early infection model in rabbits. Both standard leads and surface-mo dified leads were used. The surface modification technique was applied to achieve controlled release of the antibiotic gentamicin. The insul ating polyurethane tubing material of the leads was provided with an a crylic acid/acrylamide copolymer surface graft and then loaded with ge ntamicin. Implantation periods varied from day 4, to week 3 1/2, to we ek 10. We investigated tissue reactions in the absence of an infectiou s challenge and also the efficacy of surface-modified leads in prevent ing infection after challenge with Staphylococcus aureus was evaluated . It was demonstrated that the applied surface modification did not in duce adverse effects although during early postimplantation an increas e in infiltration of granulocytes and macrophages and wound fluid and fibrin deposition were observed. After bacterial challenge, standard l eads were heavily infected at each explantation period, denoted by abs cesses, cellular debris, and bacterial colonies. Ln contrast, little o r no infection was observed, either macroscopically or by bacterial cu ltures, with the surface-modified leads. Microscopy showed little evid ence of the bacterial challenge, and that primarily at day 4. It was c oncluded that the applied surface modification demonstrated enhanced i nfection resistance and thus represents a sound approach to the battle against infectious complications with biomaterials. (C) 1998 John Wil ey & Sons, Inc.