Thrombogenicity of a parallel-wire, self-expanding stent in an aorta loop in rats

Abstract

Thrombogenicity of a self-expanding, parallel-wire, stainless steel stent was evaluated in the aorta-loop model in rats. This was done by measuring the time interval between insertion of a heparinized loop-shaped, polyethylene cannula into the abdominal aorta of rats and occlusion of the cannula by thrombus formation, the so-called obstruction time. Obstruction time was compared in two groups of 24 rats not receiving systemic thrombolytic therapy. In one group stents were implanted proximal to the loop while in the other group a sham operation was performed. The obstruction time was not significantly different between the two groups: 94.8 ± 58.9 hours (mean ± SD) in the group without stents versus 76.3 ± 33.8 hours in the group with stents.

In 8 rats the aorta with the implanted stent was morphologically evaluated. One week after stent implantation the rods were surrounded by a small deposit of thrombus with signs of reorganization and partially covered by endothelium. The media was locally compressed by the rods. Two weeks after implantation the thrombus had completely reorganized and was covered by endothelium. In conclusion: In this model the parallel stent appeared to have low thrombogenicity.