Patient-Specific Changes in Aortic Hemodynamics Are Associated with Thrombotic Risk after Fenestrated Endovascular Aneurysm Repair with Large Diameter Endografts

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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Prognostic significance of large diameter proximal aortic neck in endovascular aneurysm repair

VASA ◽

10.1024/0301-1526/a000844 ◽

2020 ◽

Vol 49 (3) ◽

pp. 215-224

Author(s):

George A. Antoniou ◽

Aws Alfahad ◽

Stavros A. Antoniou ◽

Hassan Badri

Keyword(s):

Meta Analysis ◽

Large Diameter ◽

Prognostic Significance ◽

Endovascular Aneurysm Repair ◽

Small Diameter ◽

Aneurysm Rupture ◽

Random Effects Models ◽

Late Failure ◽

Aortic Neck ◽

Aneurysm Repair

Summary. Background: Adverse morphological features of the proximal aortic neck have been identified as culprits for late failure after endovascular aneurysm repair (EVAR). Our objective was to investigate the prognostic role of wide proximal aortic neck in EVAR. Methods: We conducted a review of the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify studies comparing outcomes of EVAR in patients with large versus small proximal aortic neck. A meta-analysis of time-to-event data was performed with the inverse-variance method and the results were reported as summary hazard ratio (HR) and 95 % CI. We applied random-effects models of meta-analysis. Results: We identified 9 observational studies reporting on a total of 7,682 patients (1,961 with large diameter and 5,721 with small diameter neck). The hazard of death (HR 1.57, 95 % CI 1.23–2.01; P = 0.0003), aneurysm-related reintervention (HR 2.06, 95 % CI 1.23–3.45; P = 0.006), type Ia endoleak (HR 6.69, 95 % CI 4.39–10.20; P < 0.001), sac expansion (HR 10.07, 95 % CI 1.80–56.53; P = 0.009), aneurysm rupture (HR 2.96, 95 % CI 2.00–4.38; P < 0.0001), and neck-related adverse events (HR 10.33, 95 % CI 4.95–21.56; P < 0.0001) was higher in patients with large diameter proximal aortic neck than in those with small neck. Conclusions: Patients with a large proximal aortic neck were found to have poorer outcomes than those with small neck. This finding has implications in decision making when selecting methods for aneurysm treatment and in EVAR surveillance for aneurysm-related complications in this cohort of patients.

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Spiral CT Angiography versus Aortography in the Assessment of Aortoiliac Length in Patients Undergoing Endovascular Abdominal Aortic Aneurysm Repair

Journal of Endovascular Therapy ◽

10.1177/152660289800500306 ◽

1998 ◽

Vol 5 (3) ◽

pp. 222-227 ◽

Cited By ~ 7

Author(s):

Matthew P. Armon ◽

Simon C. Whitaker ◽

Roger H.S. Gregson ◽

Peter W. Wenham ◽

Brian R. Hopkinson

Keyword(s):

Renal Artery ◽

Large Diameter ◽

Endovascular Aneurysm Repair ◽

Spiral Ct ◽

Abdominal Aortic Aneurysm Repair ◽

Aortic Aneurysms ◽

Aortic Bifurcation ◽

Abdominal Aortic ◽

Aneurysm Repair ◽

Level Of Agreement

Purpose: To compare measurements of aortoiliac length obtained with spiral computed tomographic angiography (CTA) and aortography in patients undergoing endovascular aneurysm repair. Methods: The distances from the lower-most renal artery to the aortic bifurcation and from the aortic bifurcation to the common iliac artery (CIA) bifurcation were measured using both CTA and aortography in 108 patients with abdominal aortic aneurysms. Results: The level of agreement between CTA and aortography was high, with 69% of aortic and 76% of iliac measurements within 1 cm and > 90% within 2 cm of each other. Mean differences were −0.35 ± 1.20 cm and 0.25 ± 1.10 cm, respectively, for aortic and iliac lengths. Aortography overestimated renal artery to aortic bifurcation length in comparison to CTA (p = 0.003), particularly in patients with large aneurysms (> 6.5 cm) and lumen diameters > 4.5 cm (p < 0.0001). Measurements of CIA length were shorter by aortography than CTA (p = 0.02). Conclusions: There is a high level of agreement between CTA and aortography in the measurement of aortoiliac length, but aortography overestimates renal artery to aortic bifurcation length in patients with large-diameter aneurysms and wide aneurysm lumens. CTA is sufficiently accurate in the majority of cases to be used as the sole basis for the construction of endovascular grafts.

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