Establishment of carotid artery in-stent restenosis models after Neuroform EZ stent implantation and their imaging and pathological studies / 中华神经医学杂志

ABSTRACT

Objective:To establish the carotid artery in-stent restenosis (ISR) models in Bama pigs after Neuroform EZ stent implantation, and observe and summarize their imaging and pathological characteristics.Methods:Thirteen healthy Bama pigs from Guangxi Province were chosen; carotid artery intima was injuried by balloon over-dilation; Neuroform EZ stents were implanted at the vascular injury sites to establish ISR models. Blood flow at areas accepted carotid artery stent implantation in Bama pigs was monitored by bedside color ultrasound every 2 weeks after surgery; once hemodynamic changes (acceleration or deceleration of the blood flow) in stents were detected, DSA, intravascular ultrasound (IVUS), optical coherence tomography (OCT) and high-resolution MRI (HR-MRI) were performed immediately. Bama pigs were then sacrificed and tissues at the stents were taken; HE staining was used to observe the pathological changes.Results:Thirteen Neuroform EZ stents were implanted into 13 Bama pigs after balloon over-dilation of the unilateral carotid arteries with a technical success rate of 100%. Hemodynamic changes in stents were detected in these 13 pigs (10 with acceleration and 3 with deceleration) at (12.46±3.57) weeks after stenting (ranged from 6-18 weeks); ISR of different degrees was found in all these 13 pigs by DSA with an average stenosis rate of (44.23±9.39)%. IVUS and OCT found that the main body of stents was covered by hyperplastic intima, and thickened intima resulted in local lumen stenosis; and obvious vascular wall enhancement in these lumens was shown on HR-MRI. HE staining showed rupture of intravascular internal elastic lamina and severely arterial intimal hyperplasia;and the hyperplastic intima was mainly composed of smooth muscle cells.Conclusion:Carotid artery ISR models in Bama pigs can be accurately and reliably established at approximately 12 weeks by tearing endovascular intima with balloon over-dilation and implanting Neuroform EZ stents, and multiple imaging and pathology methods confirm that ISR is caused by hyperplastic intima.