DEPOSITION OF PLATELETS AND NEUTROPHILS IN PORCINE ILIAC ARTERIES AFTER ANGIOPLASTY AND WALLSTENT PLACEMENT COMPARED WITH ANGIOPLASTY ALONE

Purpose. This study was designed to compare deposition of In-111-label ed platelets and neutrophils after balloon angioplasty (PTA) alone and PTA plus Wallstents. Methods. Histological investigation was performe d with scanning electron microscopy (SEM). Fifty percent stenoses of b oth iliac arteries was created by resorbable ligature in 13 pigs. Afte r 30 days, PTA was performed bilaterally with an additional stenting p rocedure done on one side. Autologous platelets were labeled and reinf used before the interventional procedure in six pigs, and labeled neut rophils were used in seven pigs. The deposition of the labeled cells w as recorded in vivo over 270 min using a scintillation camera. The res ults were correlated with in vitro measurements. Results. Scanning rev ealed significant increase in platelet and neutrophil deposition at th e site of the stent compared with the site where PTA alone was underta ken. In vitro measurements confirmed these differences. SEM demonstrat ed a fibrin lining on the stent surface and numerous adherent platelet s. The adjacent arterial lumen was almost completely covered by fibrin ous material. The PTA-alone site demonstrated denudation of endothelia l cells and less fibrinous material, as well as platelets and leukocyt es. Conclusion. The complex interaction in the response of the vessel wall and flowing blood involves both platelet and neutrophil adhesion. The self-expandable vascular endoprosthesis contributes to increased deposition of platelets and neutrophils as seen in this experimental m odel of nonatheromatous stenosis.