Pressure rinsing of coronary stents immediately before implantation reduces inflammation and neointimal hyperplasia

OBJECTIVES This study evaluates whether rinsing stems with high pressure immediately before implantation minimizes stunt-induced inflammation and neointimal formation. BACKGROUND Several reports indicate that manual stent manipulation before implantation results in foreign body contamination and increased neointimal hyperplasia. METHODS A stent-cleaning chamber was developed to rinse stems at a sustained hydrodynamic pressure of 4 atm for 10 s. Commercial pre-mounted stems were examined with different levels of manipulation: 1) untouched stems: no stent manipulation before implantation; 2) handled stems: manual stent re-crimping on the balloon; 3) rinsed stems: pressure-rinsed with the stent-cleaning chamber. In vitro surface analysis was evaluated by scanning electron microscopy. Neointimal hyperplasia and inflammation around stent struts were also assessed in the pig in-scent restenosis model. RESULTS In vitro analysis revealed fewer contaminants on rinsed stems compared with untouched (p = 0.01) and handled stems (p < 0.001). In vivo, neointimal thickness, neointimal area and vessel percent stenosis were significantly reduced in rinsed, compared with nut-rinsed, stems (p = 0.002, p = 0.007, p = 0.008 respectively). In addition, a significant reduction in the inflammatory infiltrate around struts was observed in untouched, compared with handled, stems (p = 0.04) and in rinsed, compared with not-rinsed, stents (p < 0.001). Regression analysis accounting for injury and neointimal thickness showed significant differences in slopes between "handled + not-rinsed" and "handled + rinsed" stems (p = 0.004), and between "untouched + not-rinsed" and "untouched + rinsed scents" (p = 0.037). CONCLUSIONS Rinsing scents under high pressure immediately before coronary implantation results in less inflammation around struts and thinner neointima at 28 days in this pig model. (J Am Coll Cardiol 2001;38:562-8) (C) 2001 by the American College of Cardiology.