In vitro evaluation of platelet reactivity toward annuloplasty devices treated with heparin coating: Studies under flow conditions

We have applied an in vitro perfusion model to explore the potential thrombogenicity of polyester annulolasty fabric used in valve repair and to investigate the possible thromboresistance characteristics conferred by a special heparin coating (Duraflo™ treatment). Samples of human blood from i) untreated or ii) heparin‐coated extracorporeal circuits were recirculated through annular perfusion chambers containing a) untreated or b) treated annuloplasty cloth material. Perfusion experiments were performed at a shear rate of 600 s−1 for 20 min. Platelet interaction with the material was morphometrically evaluated. In experiments performed with blood from untreated circuits and cloth material, the average cross‐sectional area of platelet mass was 615 ± 135 μm2. Treatment of cloth material with Duraflo™ statistically decreased the area of interacting platelets to 319 ± 101 μm2 (*p < 0.05, n = 10). Blood samples from heparin‐coated extracorporeal circuits showed a decrease of total area of platelets (308 ± 58 μm2 vs 138 ± 30 μm2, *p < 0.05, n = 9). The combined treatment of Duraflo™ in extracorporeal circuits and cloth material caused a more consistent reduction (p < 0.05). The in vitro perfusion experimental model was sensitive to evaluate the thrombogenic potential of Duraflo™ treatment. Our results indicate that the heparin coating of cloth material and extracorporeal circuits improves the biocompatibility of the original material and reduces the thrombogenic profile. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005