Histologic Analysis with the Newly Designed Exoskeleton Seal((R)) Stent-Graft in the Porcine Abdominal Aorta

Abstract

PurposeTo investigate the technical feasibility of a novel exoskeleton Seal((R)) stent-graft and analyze early histologic changes in the porcine abdominal aorta.Materials and MethodsSix pigs received an abdominal stent-graft (Group I), and six received an iliac branch stent-graft (Group II). Groups were subdivided as follows: Group Ia, which received three bifurcated main-body stent-grafts; Group Ib, which received three bifurcated main-body stent-grafts with both iliac graft-stents; Group IIa, which received three simple uni-iliac tapered stent-grafts; and Group IIb, which received three uni-iliac tapered tapered stent-grafts with right straight limb and left branched limb. Statistical analyses were performed with the Wilcoxon signed-rank test and mixed-model regression analysis.ResultsThe primary technical success rate (<24h) was 83% because of two acute thromboses in the lumen of the stented abdominal aorta immediately after stent-graft placement. At 4weeks, late thrombosis occurred in two pigs. Higher mean neointimal hyperplasia areas (23.5% vs. 16.2%; P=.047), neointimal hyperplasia thicknesses (545.5 mu m vs. 422.2 mu m; P=.001), and degrees of collagen deposition (2.71 vs. 2.33; P=.002) were observed at the bare-metal stent-graft compared with the proximal exoskeleton portion of the stent-graft, with no significant differences between the patent and occluded groups or among the four types of stent-grafts.ConclusionsThe exoskeleton stent-graft demonstrates 66% of patency rate during 1-month follow-up due to four cases of thromboses; however, the endothelialization on the junction of proximal graft showed no significant differences between the patent and occluded groups. Further studies should investigate long-term outcomes with prolonged neointimal hyperplasia.