The rabbit superior mesenteric artery as an in vivo model for perforator artery occlusion assessment after flow diversion.

Abstract

OBJECTIVE: Covering side branches with flow diverters (FDs) raises concerns regarding side branch occlusion and potentially delayed ischemic complications. Existing preclinical models fail to replicate these risks. We developed a novel preclinical model using the rabbit superior mesenteric artery (SMA) to investigate FD-associated branch occlusion and neointimal changes. MATERIAL AND METHODS: Eighteen rabbits were enrolled; three were excluded for periprocedural complications. Fifteen animals completed follow-up, each with a single FD implanted in the SMA (one of three Pipeline Embolization Devices: 5 Bare-Flex, 4 Shield-Flex, and 6 Vantage). Branch patency (using Digital subtraction angiography DSA and histology) and ostial coverage/neointima (using optical coherence tomography OCT), were assessed at 1 or 3 months. Results were compared between-(FD and time) groups using Mann-Whitney and Kruskal-Wallis test. RESULTS: Fifteen animals completed the study. Among 35 covered branches, 30 (85.7%) remained patent, 4 (11.4%) were pre-occlusive, and 1 (2.9%) occluded. Median ostium coverage by OCT was 77.0%. Mean in-stent stenosis was 35.0%. No significant difference were found across FD types or timepoints comparing patency, medium ostium coverage, in-stent stenosis. Histology confirmed progressive neointimal maturation and partial to full ostium coverage, with strong correlation to OCT findings. No correlation was found between neointimal thickness and ostium coverage. CONCLUSION: The rabbit SMA model successfully detected rare occlusions and common pre-occlusive changes, approaching clinical data. This model may help to evaluate FD safety, optimize design, and investigate endothelial responses.