Experimental Study of Balloon-expandable Metallic Vena Caval Stents in Rabbits

The reactivity and patency of balloon-expandable Strecker stents were determined in the superior vena cava (SVC) and inferior vena cava (IVC) of rabbits. One stent was placed in each of 24 rabbits; 15 were placed in the SVC and nine in the IVC. The duration of stent placement varied between 3 days and 15 months. After the animals were killed, the segments in which the stent was placed were sectioned and analyzed under light microscopy for quantification of neointimal hyperplasia with metal struts in situ. Twenty-three stents remained patent throughout. Two SVC stents thrombosed at 1 week; one of these recanalized spontaneously after 4 weeks. Self-limiting neointimal hyperplasia reached a maximum thickness at 1 month and receded over 3–6 months. In five rabbits with long-term SVC stents, there was a radial shift of the stent to the perivascular layer of fat. Despite this shift, these stents remain patent. Strecker stents are well adapted to the venous system in terms of both patency and histocompatibility.