Serial late dilatations of expanded polytetrafluoroethylene‐covered stents in porcine aorta

BACKGROUND: Covered stents may be desirable for stenting of coarctations. OBJECTIVES: To evaluate the ability of Atrium expanded polytetrafluoroethylene (ePTFE)-covered stents to be implanted and then serially dilated to the size of the adjacent aorta during a rapid growth period in swine. METHODS: Eight Yorkshire pigs (7 females) with a mean weight of 18.3 +/- 0.7 kg had an Atrium ePTFE-covered stent deployed in the descending aorta. Five of these animals also had an identical Atrium bare metal stent (BMS) control deployed in the descending aorta. All swines were recatheterized with the first dilatation of the stents to 14 mm at day 100. Four of these animals were recatheterized at day 145 and euthanized, and the remaining four swine were recatheterized with a second dilatation to 18-20 mm, 195 days after initial implantation. RESULTS: All stents were deployed without device malfunction, and both uncovered and covered stents were successfully dilated from 10 to 11 mm to the size of the adjacent aorta (16-20 mm). There was no gradient across either type of stent on recatheterization and all stents were well sized to the native aorta. Only the size of the aorta limited the degree of stent dilatation. The Atrium covered stents consistently recoiled after maximal dilatation and required higher pressures for further expansion. Gross damage to the aorta was noted in two animals in which stents were dilated to >20% the diameter of the native aorta. In stent neointimal thickness was equivalent for both types of stent. CONCLUSIONS: Atrium ePTFE-covered stents can be implanted at 10-11 mm and serially dilated to accommodate for rapid aortic growth. High pressure balloons are required for dilatation of ePTFE-covered stents. Atrium covered stents exhibited more recoil and foreshortening at larger diameters.