Patient-Specific Simulation Prior to Endovascular Aneurysm Repair: The Use of 3D Printed Aneurysms

The endovascular treatment of abdominal aortic aneurysm (EVAR) consists of inserting a delivery system through intravascular pathway and deploying one or several stent-grafts at the aneurysm site in order to exclude it. This procedure has proven to have a high success rate for eligible patient population and benefits in terms of reduced blood loss, intraoperative morbidity and length of hospital stay. As the selection criteria for EVAR extend progressively due to enhancements in the devices and delivery systems, clinicians are confronted with cases becoming increasingly difficult and demanding procedures with steep learning curve (aortic dissection, branched and fenestrated stent-graft, and complex anatomy with high tortuosity or short aortic neck). In this context patient-specific Finite Element Modeling (FEM) could provide a predictive tool to support endovascular device assessment and selection as well as intervention planning. Given the lack of dedicated solutions, the aim of this study was to assess the feasibility of simulating the main steps of EVAR procedure, from guidewire insertion to stent-graft deployment.

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Impact of Insertion Technique and Iliac Artery Anatomy on Fenestrated Endovascular Aneurysm Repair

Journal of Endovascular Therapy ◽

10.1177/1526602819872499 ◽

2019 ◽

Vol 26 (6) ◽

pp. 797-804

Author(s):

Sean A. Crawford ◽

Matthew G. Doyle ◽

Cristina H. Amon ◽

Thomas L. Forbes

Keyword(s):

Stent Graft ◽

Iliac Artery ◽

Flexural Rigidity ◽

Endovascular Aneurysm Repair ◽

Patient Specific ◽

Bending Rigidity ◽

Insertion Technique ◽

3 Dimensional ◽

Aneurysm Repair

Purpose: 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. Materials and Methods: 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. Results: In the rigid idealized models, stent-graft rotation increased with increasing torsion; torsion levels of 1.6, 2.6, and 3.6 mm−1 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−1 net torsion and 254 N·m2 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°. Conclusion: 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.

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Utilizing patient-specific 3D printed guides for graft reconstruction in thoracoabdominal aortic repair

Scientific Reports ◽

10.1038/s41598-021-97541-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Taehun Kim ◽

Dayeong Hong ◽

Junhyeok Ock ◽

Sung Jun Park ◽

Younju Rhee ◽

...

Keyword(s):

Thoracoabdominal Aortic Aneurysm ◽

Patient Specific ◽

New Techniques ◽

3D Printed ◽

Thoracoabdominal Aortic Aneurysm Repair ◽

Branched Graft ◽

Aneurysm Repair ◽

Segmental Arteries ◽

Aortic Aneurysm Repair ◽

Graft Reconstruction

AbstractIn thoracoabdominal aortic aneurysm repair, repairing the visceral and segmental arteries is challenging. Although there is a pre-hand-sewn and multi-branched graft based on the conventional image-based technique, it has shortcomings in precisely positioning and directing the visceral and segmental arteries. Here, we introduce two new reconstruction techniques using patient-specific 3D-printed graft reconstruction guides: (1) model-based technique that presents the projected aortic graft, visualizing the main aortic body and its major branches and (2) guide-based technique in which the branching vessels in the visualization model are replaced by marking points identifiable by tactile sense. We demonstrate the effectiveness by evaluating conventional and new techniques based on accuracy, marking time requirement, reproducibility, and results of survey to surgeons on the perceived efficiency and efficacy. The graft reconstruction guides cover the segmentation, design, fabrication, post-processing, and clinical application of open surgical repair of thoracoabdominal aneurysm, and proved to be efficient for accurately reconstructing customized grafts.

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