[Stent coated with bovine pericardium: in vitro evaluation, in animals, and initial results in humans]

Covering a stent with a membrane (stent graft) allows treatment of diverse coronary abnormalities such as aneurysms, rupture and fistulas (which, until recently, required surgical therapy). A stent graft could also reduce embolic complications associated with angioplasty of saphenous vein grafts. The objective of this study is to evaluate bovine pericardium as a graft for conventional stents. In vitro testing of the bovine pericardium disclosed an elasticity of 15% and a resistance to rupture of 0.22 kg/mm2, well above the pressure commonly used during stent deployment. In 18 pigs, 29 of 32 (90.63%) attempts to implant stent grafts were successful. Histology of acute porcine studies revealed correct apposition of the stent graft to the vessel wall, subacute and chronic (10 days and 1 month) samples showed adequate endothelization and exclusion of proliferative media. Twenty stents were placed in 15 patients with a 100% success rate. Seven patients had coronary aneurysms and in all a complete exclusion of the aneurysm was obtained without complications. Fourteen patients have a follow-up of 6 or more months with evidence of clinical restenosis in 2 (14.28%), whereas angiographic follow-up in 9 patients, which included the 2 cases with recurrent angina, evidenced restenosis in 3 of 14 stents (21.4%), two of which were overlapped in the LAD of one patient and one corresponded to a series of 9 stents (in 5 patients) placed in saphenous vein grafts. It is concluded that bovine pericardium is a suitable material for stent-grafts and its efficacy to seal coronary aneurysms was demonstrated. These results warrant a larger comparative study to better define its restenosis rate and further delineate its usefulness in the treatment of diseased saphenous vein grafts.