The biggest problem with cardiac pacemakers is that the leads, which are often made of polyurethane, are susceptible to biodegradation by enzymatic body fluids. Spire has developed an innovative process for deposition of adherent metallic coatings on polymers, Ion Beam Assisted Deposition (IBAD). This program will employ IBAD to coat polyurethane pacemaker leads with platinum, eliminating problems deriving from biodegradation. IBAD is an advanced low temperature coating process which combines evaporation with concurrent ion bombardment to produce an adherent, uniform, and pin hole free coating. Spire has already used it in preliminary trials to coat silicone rubber with platinum, and results have been very encouraging. Microscopy and conventional peel testing show these coatings to be fully dense, pin hole free, and adherent. The feasibility of coating polyurethane pacemaker leads with platinum by IBAD will be demonstrated in Phase I. A number of polyurethane coupons and leads will be coated and tested. Testing will focus upon three areas. First, properties of coating will be assessed with various tests. Experiments will be performed for durability, adhesion, uniformity, and density. Second, biocompatibility will be determined from cytotoxicity and systemic injection tests. The final area of testing will concentrate on changes which are induced by the coating on the original properties of the leads, such as tensile strength and stiffness.
