Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada.
J Endovasc Ther. 2019 Dec;26(6):797-804. doi: 10.1177/1526602819872499. Epub 2019 Aug 28.
To develop a mechanically realistic aortoiliac model to evaluate anatomic variables associated with stent-graft rotation and to assess common deployment techniques that may contribute to rotation. Idealized aortoiliac geometries were constructed either through direct 3-dimensional (3D) printing (rigid) or through casting with polyvinyl alcohol using 3D-printed molds (flexible). Flexible model bending rigidity was controlled by altering wall thickness. Three flexible patient-specific models were also created based on the preoperative computed tomography angiograms. Zenith infrarenal and fenestrated devices were used in this study. The models were pressurized to 100 mm Hg with normal saline. Deployments were performed under fluoroscopy at 37°C. Rotation was calculated by tracking the change in position of gold markers affixed to the devices. In the rigid idealized models, stent-graft rotation increased with increasing torsion; torsion levels of 1.6, 2.6, and 3.6 mm had mean rotations of 5.2°±0.03°, 11.2°±4.8°, and 27.6°±13.0°, respectively (p<0.001). In the flexible models, the highest rotation (58°±3.0°) was observed in models with high torsion and high rigidity (7.5 mm net torsion and 254 N·m flexural rigidity). No rotation was observed in the absence of torsion. Applying torque to the device during insertion significantly increased stent-graft rotation by an average of 28° across all levels of torsion (p<0.01). Multiple device insertions prior to deployment did not change the observed device rotation. The patient-specific models accurately predicted the degree of rotation seen intraoperatively to within 5°. Insertion technique plays an important role in the degree of stent-graft rotation during deployment. Our model suggests that in vivo correction of device orientation can increase the observed rotation and supports the concept of fully removing the device, adjusting the orientation, and subsequently reinserting. Additionally, increasing iliac artery torsion in the presence of increased vessel rigidity results in stent-graft rotation.
为了开发一种机械逼真的腹主动脉模型，以评估与支架移植物旋转相关的解剖学变量，并评估可能导致旋转的常见部署技术。通过直接三维（3D）打印（刚性）或使用 3D 打印模具通过聚乙醇 casting（柔性）来构建理想的腹主动脉几何形状。通过改变壁厚来控制柔性模型的弯曲刚度。还根据术前计算机断层血管造影创建了三个柔性患者特定模型。本研究中使用了 Zenith 肾下型和开窗型装置。用生理盐水将模型加压至 100mmHg。在 37°C 下透视下进行部署。通过跟踪固定在装置上的金标记的位置变化来计算旋转。在刚性理想模型中，支架移植物的旋转随扭转增加而增加；扭转水平为 1.6、2.6 和 3.6mm 的平均旋转角度分别为 5.2°±0.03°、11.2°±4.8°和 27.6°±13.0°（p<0.001）。在柔性模型中，在扭转和刚度较高（7.5mm 净扭转和 254N·m 弯曲刚度）的模型中观察到最大旋转（58°±3.0°）。在没有扭转的情况下观察不到旋转。在插入过程中对装置施加扭矩会使支架移植物的旋转平均增加 28°，扭转程度为所有级别（p<0.01）。在部署前进行多次装置插入不会改变观察到的装置旋转。患者特定模型准确预测了术中观察到的旋转程度，误差在 5°以内。插入技术在部署过程中支架移植物旋转的程度中起着重要作用。我们的模型表明，体内校正装置方向可以增加观察到的旋转，并支持完全移除装置、调整方向和随后重新插入的概念。此外，在增加血管刚性的同时增加髂动脉扭转会导致支架移植物旋转。
