Hydrophilic surface endoluminal stents modification of metallic

Purpose: Stainless steel endovascular stents are inherently thrombogenic so that thrombus accumulates on these devices, leading to acute vessel occlusion. A potential solution to this problem is stent surface modification with hydrophilic polymers, which might lirnit platelet adhesion and reactivity. Methods: N-vinylpyrrolidone (NVP) and potassium sulfopropyl acrylate (KSPA) hydrophilie monomers were ~/graft polymerized onto 1 cm e stainless steel slabs and 4 mm Palmaz stalnless steel stents. Surface characteristics of modified and plain stainless steel stents were then investigated with contact angle and x-ray photoelectron spectroscopy measurements, and in vitro and in vivo platelet reactivity was assessed as 1 nindium platelet accumulation expressed as counts/min/cm 2. Results: Surface modification of stainless steel slabs and stents with both NVP and KSPA hydrophilic polymers significantly reduced in vitro platelet adhesion (plain = 2249 + 723 cotmts/min/cm 2, NVP = 428 + 156 counts/min/cm 2, KSPA = 958 + 223 counts/min/ cm 2) and in vivo platelet accumulation after 1 hour of blood flow exposure (plain = 1407 + 796 counts/min/cm 2, NVP = 426 + 175 cotmts/min/cm 2, KSPA = 399 + 124 counts/min/cm2). In addition, platelet accumulation on modified stents indexed to plain stents was lowest in KSPA-modified stents (NVP = 79.3% + 31.7% of plain, KSPA = 51.2% -+ 36.2% ofplain). Surface analysis confirmed surface grafting with both monomers, and SEM documented smoothing of the irregular surfaces of the stainless steel stents after grafting. Conclusion: Hydrophilic polymer surface modification of stainless steel stents decreases initial steht surface platelet accumulation, which may decrease the risk ofvessel thrombosis associated with the use of these devices. (J Vasc SuRa 1995;22:327-36.)