Centre for Applied Biomedical Engineering Research, MSSi, Department of Mechanical and Aeronautical Engineering, University of Limerick, Ireland.
J Endovasc Ther. 2010 Feb;17(1):95-107. doi: 10.1583/09-2920.1.
To develop an improved methodology for investigating the parameters influencing stent-graft migration, with particular focus on the limitations of existing methods.
A physiological silicone rubber abdominal aortic aneurysm (AAA) model for fixation studies was manufactured based on an idealized AAA geometry: the model had a 24-mm neck, a 50-mm aneurysm, 12-mm-diameter legs, a 60 degrees bifurcation angle, and 2-mm-thick walls. The models were authenticated in neck fixation experiments. The displacement force required to migrate stent-grafts in physiological pulsatile flow was tested dynamically in water at 37 degrees C. A commercially available longitudinally rigid stent-graft (AneuRx) and a homemade device with little longitudinal rigidity were studied in a number of different configurations to investigate the effect of neck fixation length and systolic pressure on displacement force.
The AneuRx (6.95+/-0.49 to 8.52+/-0.5 N) performed significantly better than the homemade device (2.57+/-0.11 to 4.62+/-0.25 N) in pulsatile flow. The opposite was true in the neck fixation tests because the longitudinal stiffness of the AneuRx was not accounted for. Increasing pressure or decreasing fixation length compromised the fixation of the homemade device. This relationship was not as clear for the AneuRx because decreasing proximal fixation resulted in an increase in iliac fixation, which could assist fixation in this device.
Assessing the migration resistance of stent-grafts based solely on proximal fixation discriminates against devices that are longitudinally stiff. Current in vivo models may give inaccurate displacement forces due to the high degree of oversizing in these studies. A novel in vitro approach, accounting for longitudinal rigidity and realistic graft oversizing, was developed to determine the resistance of aortic stent-grafts to migration in the period immediately after device implantation.
开发一种改进的方法来研究影响支架移植物迁移的参数，特别关注现有方法的局限性。
根据理想的腹主动脉瘤（AAA）几何形状制造了一种用于固定研究的生理硅橡胶 AAA 模型：该模型具有 24mm 的颈部、50mm 的瘤体、12mm 直径的支脚、60 度的分叉角和 2mm 厚的壁。对模型进行了颈部固定实验验证。在 37°C 的生理脉动流中动态测试了在水中迁移支架移植物所需的位移力。研究了一种商用纵向刚性支架移植物（AneuRx）和一种纵向刚性较小的自制装置，在多种不同配置下研究了颈部固定长度和收缩压对位移力的影响。
AneuRx（6.95+/-0.49 至 8.52+/-0.5 N）在脉动流中明显优于自制装置（2.57+/-0.11 至 4.62+/-0.25 N）。在颈部固定测试中则相反，因为 AneuRx 的纵向刚度未被考虑在内。增加压力或减少固定长度会削弱自制装置的固定。对于 AneuRx 来说，这种关系并不明显，因为近端固定减少会导致髂固定增加，这可以在该装置中辅助固定。
仅基于近端固定评估支架移植物的迁移阻力会歧视纵向刚性较大的装置。由于这些研究中存在高度的过度扩张，当前的体内模型可能会给出不准确的位移力。为了确定支架移植物在植入后立即抵抗迁移的能力，开发了一种新的体外方法，该方法考虑了纵向刚性和现实的移植物过度扩张。
