BLOOD CONTACT WITH ARTIFICIAL SURFACES DURING BVAD SUPPORT

Persistently elevated levels of cytokines (IL-6, IL-8) during the cour se of mechanical circulatory support correlate well with fatal outcome . To determine the influence of blood/artificial surface interaction o n the chronic inflammatory process, we studied the biocompatibility of silicone and polyurethane membranes in vitro. Cultures of isolated mo nonuclear cells or whole blood were incubated for 24 hours in tubes co ated with silicone or polyurethane, both used in the construction of v entricular assist systems. Concentrations of several inflammatory medi ators were measured in the supernatant. Our results can be summarized as follows: a) Monocytes were stimulated to release inflammatory cytok ines like IL-8 and MIP-1a, particularly when silicone was involved; b) Both silicone and polyurethane stimulated thrombocytes thus resulting in the release of P-Selectin and PDGF-AB, although polyurethane was a stronger stimulus, c) Moderate complement activation was triggered by contact with either of the artificial surfaces. However, the preventi on of most of these effects by coating the artificial surface with pro tein and the lack of correlation between in vitro data and serum level s of IL-6 and IL-8 during the course of circulatory support suggest th at the persistence of inflammatory cytokines during BVAD support is no t caused by blood/surface interaction.