Comparison of Tissue Reaction with Three Different Endografts Used for Exclusion of Carotid Artery Aneurysm in a Dog Model

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Abstract

PURPOSE

To assess the efficacy and biocompatibility of balloon-expandable stainless-steel stents covered with various membrane types.

MATERIALS AND METHODS

Stents covered with biomembrane (ie, piglet greater omentum vein), polyurethane, or expanded polytetrafluoroethylene (ePTFE;n= 12 each) were implanted into the 36 bilateral carotid arteries of 18 dogs to treat 36 surgically created saccular side wall aneurysms. Treated dogs were administered anticoagulation therapy after stent implantation. Angiography was performed immediately after the procedure and at 2, 4, and 12 weeks. Aneurysm isolation, primary parent artery patency, acute thrombosis in the stent, and endoleak were investigated. Two dogs in each group were killed at each follow-up interval, the stent-implanted arteries were removed for light and electron microscopy, and aneurysm thrombosis, stenosis rate, and endothelialization progress were observed.

RESULTS

Thirty-six stents were successfully placed and 36 aneurysms completely isolated, with no endoleaks revealed by immediate or follow-up angiography. The primary patency rates of the biomembrane-, polyurethane-, and ePTFE-covered stents were 91.7%, 50%, and 66.7%, respectively. At 12 weeks, a luminal narrowing of 24.27% ± 6.23% was seen in the biomembrane group, compared with 30.78% ± 1.41% (P= .025) in the polyurethane group and 20.56% ± 7.22% (P= .247) in the ePTFE group. All treated aneurysmal pouches had filled with thrombi and stent wires were encased by extended neointima. Endothelialization in the biomembrane group had begun by 2 weeks, which was earlier than in the polyurethane or ePTFE groups.

CONCLUSIONS

All three stent-grafts successfully excluded carotid aneurysms. Biomembrane-covered stents showed better primary patency and less intimal hyperplasia than polyurethane- or ePTFE-covered stents.

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