Thromboembolic Events with Enterprise Versus Pipeline: Porcine In Vivo Experiment

BACKGROUND: Thromboembolic complications are serious adverse events associated with stenting of intracranial aneurysms. For the development of novel devices, currently no practical model exists to evaluate distal embolic events. The purpose of the current study was 2-fold: 1) assess the feasibility of a porcine carotid bifurcation model for in vivo testing of stent thrombogenicity and 2) compare the thrombogenicity of the Enterprise vascular reconstruction device versus the Pipeline embolization device (PED). METHODS: Six Yorkshire pigs underwent implantation of size-matched devices across the carotid bifurcation. Each animal received 1 Enterprise and 1 PED contralaterally. Baseline and 2-week follow-up angiography were performed. Images were analyzed including detailed measurements of the rete mirabile, a small-vessel conglomerate supplied by branches of the common carotid artery. RESULTS: In the absence of thromboembolic events at 2 weeks (n = 8), the perfused rete area measured 134.4 +/- 6.9 mm(2). In the presence of thromboembolic events (n = 4), the perfused rete was reduced to an area covering 37.1 +/- 8.6 mm(2) (P < 0.01). There was no difference in thrombogenicity between Enterprise and PED with a thromboembolic event rate of 33.3% for both devices (P > 0.99). CONCLUSION: The swine carotid stent model allows in vivo analysis of device-related thrombogenicity and distal embolic event rates. Size reduction of the perfused rete mirabile indicates the presence of thromboembolic events. Both Enterprise and PED were associated with similar thrombogenicity in this experiment.