Heparin release from slippery-when-wet guide wires for intravascular use

Thin metallic wires with an adherent hydrophilic/ lubricious polymeric coating were manufactured in a new extrusion-like procedure. This procedure is part of a novel and efficient way of assembling lubricious guide wires for intravascular interventions, such as percutaneous transluminal angioplasty. It is reported that heparin can readily be incorporated in the hydrophilic coating. A set of heparin-containing guidewire models was made and studied in detail. This showed that (i). immersion of the guide-wire models in an aqueous environment leads to release of heparin from their surface; (ii). the presence of heparin in the coating does not impede the lubricity of the coils; (iii). addition of stearic acid in the coating, next to heparin, does not influence the lubricity of the guide-wire models. Two different charges of heparin (designated heparin-low and heparin-high) were incorporated in the coating. It is discussed that release of heparin from the surface of medical devices (e.g. guide wires and catheters) is much more effective than systemic heparinization, basically because dissolved heparin molecules have a much larger probability of simply passing a medical device's surface (axial convection) rather than contacting it (radial diffusion).