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 annulo- lasty fabric used in valve repair and to investigate the possible thromboresistance characteristics conferred by a special hepa- rin coating (Duraflo™ treatment). Samples of human blood from i) untreated or ii) heparin-coated extracorporeal circuits were recirculated through annular perfusion chambers con- taining 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 mor- phometrically evaluated. In experiments performed with blood from untreated circuits and cloth material, the average cross- sectional area of platelet mass was 615 135 m 2 . Treat- ment of cloth material with Duraflo™ statistically decreased the area of interacting platelets to 319 101 m 2 (*p 0.05, n 10). Blood samples from heparin-coated extracorporeal circuits showed a decrease of total area of platelets (308 58 m 2 vs 138 30 m 2 ,* 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 eval- uate 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 75A: 192-198, 2005