ABSTRACT
Objective:To establish the common carotid artery aneurysm models of Wallstent double stent overlapping implantation in miniature pigs, and evaluate the safety and effectiveness of this procedure by observing the imaging and pathological changes.Methods:Sidewall aneurysm and fusiform aneurysm models in Bama miniature pigs were established surgically and 2 Wallstent stents were overlapped and implanted in situ. Aneurysm healing immediately after surgery and during 8 weeks of follow-up were evaluated according to 2D-DSA by O'Kelly-Marotta (OKM) grading scale and Kamran scale; degrees of stent adhesion immediately after surgery and status of stent endothelialization and aneurysm healing at 2, 4, and 8 weeks after surgery were observed by high resolution C-arm CT(HR-CBCT) and optical coherence tomography (OCT); and the changes of stent endothelialization were evaluated by comparing the HR-CBCT and OCT results with histopathology at 8 weeks after surgery. Perioperative adverse events were recorded.Results:After successful establishment of common carotid artery aneurysm models (including 4 sidewall aneurysms and 4 fusiform aneurysms with average diameter of [11.0±2.8] mm) in 8 miniature pigs, a total of 16 Wallstent stents (2 in each aneurysm) were implanted across the aneurysmal neck, with a technical success rate of 100%. No serious complications such as acute stent thrombosis, or aneurysm rupture and bleeding were observed in the perioperative period. The 2D-DSA immediately after surgery showed obvious intracranial contrast agent retention in 6 patients (1 patient in grading 1, 3 in grading 2, and 2 in grading 3) and aneurysm occlusion in 2 patients (grading 4). Eight weeks after follow-up, all 8 aneurysms had complete occlusions (grading 4); and 2 experimental pigs had in-stent restenosis, with stenosis rates of 52% and 67%, respectively. HR-CBCT and OCT immediately after surgery and during follow-up indicated that the stent metal braid was gradually covered by proliferating intima, with disappeared aneurysm. The cause of in-stent restenosis in 2 experimental pigs was local intima hyperplasia resulted from poor stent adhesion, and pathological findings indicated that the intima hyperplasia was mainly composed of smooth muscle cells and fibrous connective tissues.Conclusion:In animal models, Wallstent stent overlapping implantation is safe and effective in common carotid aneurysms, but intraoperative adverse adhesion of overlapping stent should be avoided.