Background Thromboembolic complications are the most common adverse events associated with extracranial and intracranial stent placement. Currently no model exists for evaluation of distal embolic events that allows for testing of novel stent devices. The purpose of this study was to assess the feasibility of a porcine carotid bifurcation model for the evaluation of thromboembolic events after stent placement.

Materials and methods Six Yorkshire pigs underwent implantation of an Enterprise vascular reconstruction device (Enterprise) across the carotid bifurcation and a size-mathced pipeline embolization device (PED) was placed across the contralateral carotid bifurcation. The porcine rete mirabile, a small vessel conglomerate between the extra and intracranial circulation, acted as a filter for embolic debris. Two weeks after stent placement, follow up catheter angiography was performed and the size of the rete mirabile was measured to determine the incidence of thromboembolic events.

Results Two pigs in the Enterprise group (33%) and two pigs in the PED group (33%) had distal thromboembolic events. Of the pigs with no thromboembolic event present at 2 weeks, the rete height measured 17.0±0.6 mm, the width 8.8±0.4 mm, and the rete area 134.4±6.9 mm² (n=8). For the animals with thromboembolic events (n=4), the perfused rete was reduced to a height of 9.5±0.9 mm, a width of 4.6±0.1 mm, covering an area of 37.1±8.6 mm² (p<0.01). There was no difference in rates of thromboembolic events between the two devices. Neoendothelialization was noted to be more pronounced with PED compared to Enterprise.

Discussion This study shows that the porcine carotid bifurcation is a useful in-vivo model for assessment of stent thrombogenicity. Distal embolic events are characterized by stent/branch occlusions, the endothelial response and a reduction in size of the rete mirabile. While the PED was associated with increased neoendothelialization compared to the Enterprise, both devices demonstrated similar thrombogenicity.

Disclosures A. Griffin: None. E. Hauck: None.