SINGLE AND TANDEM STENTS IN SHEEP ILIAC ARTERIES - IS THERE A DIFFERENCE IN PATENCY

Purpose: To compare patency and neointima formation of single and tand em arterial stents. Methods: In each of six sheep, two Memotherm nitin ol stents (tandem stents) were inserted into the external iliac artery on one side and a single stent into the artery on the opposite side. The size of the iliac lumen was assessed in the proximal, middle, and distal segments of the stents by intravascular ultrasound (IVUS) befor e, immediately after, and 1 month after implantation when the sheep we re killed. Neointimal thickness was determined in the proximal, middle , and distal segments of each stent by light microscopy. Results: All stents remained patent. There was no significant difference in lumen a nd neointimal thickness between single and tandem stents. Cranial tand em stents showed a significantly wider lumen and smaller neointimal th ickness than caudal tandem stents. In the proximal and distal segments , the lumen of the stents was significantly smaller and the neointimal thickness greater than in the middle segment; differences in neointim al thickness were significant only between the proximal and the middle segment. Conclusion: In an experimental setting, tandem stents did no t interfere with one another with regard to patency and neointima form ation when compared with a single contralateral stent. Neointimal thic kening after stent insertion seems to be inversely related to the orig inal arterial diameter.