Thromboresistant stents

Optimal stent implantation and new antiplatelet therapy have reduced the thrombotic complication after stent implantation, dramatically. However, thrombosis remains a challenge in some lesions and patient subgroups. As an initial and unavoidable event during stent implantation, thrombosis and platelet activation are also involved in the development of neointimal hyperplasia. Stents coated with heparin and other antithrombotic drugs have been demonstrated to decrease thrombotic complications, although their effect on neointimal hyperplasia remains uncertain. As heparin is attached to the stent surface, we divide thromboresistant stents as heparin-coated stents and drug-eluting thromboresistant stents. 

Table 2 Thromboresistant drug-eluting stents (Continued)...

Table 3). Mural thrombi may serve as a scaffold for subsequent cell proliferation and undergo organization. However, early thrombus formation alone is not responsible for the development of neointimal hyperplasia. As discussed earlier, controversial results on neointimal hyperplasia with thromboresistant stents have been reported. 

Thierry B, Winnik FM, Merhi Y, Silver J, Tabrizian M. Radionuclides-hyaluronan-conjugate thromboresistant coatings to prevent in-stent restenosis. Biomaterials 2004 25 3895-3905. 

To determine whether the CS/HA multilayers may be exploited as in situ drug delivery system, sodium nitroprusside (SNP) was incorporated in the multilayers. SNP, a nitrous oxide dmior that spraitaneously decomposes in biological environments [153], is extensively used clinically to reduce blood pressure and has emerged as a promising modality in the treatment of restenosis [154]. SNP-loaded multilayers have been shown to reduce platelet adhesion below that associated with multilayers devoid of the drug. The enhanced thromboresistance of the self-assem-bled multilayer, together with the anti-inflammatory and wound healing properties of HA and chitosan, are expected to reduce neointimal hyperplasia that is associated with stent implantation. 

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