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Rynio P, Gutowski P, Kazimierczak A. Physician-Modified Stent-Grafts Created in the Three-Dimensionally Aortic Template Have Better Reliability and Greater Alignment With the Target Vessels Than Stent-Grafts Modified Based on Measurements From Computed Tomography. J Endovasc Ther 2023; 30:769-778. [PMID: 35543452 DOI: 10.1177/15266028221095396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Physician-modified stent-grafts (PMSG) are widely used, especially when a patient's condition precludes waiting for a custom-made device. In recent years, the modification process has been upgraded using 3-dimensional (3D) aortic templates. Nonetheless, the reliability of PMSG and accuracy of fenestration alignment with the target vessel are not known. Thus, the study is aimed to fulfill the gap in current knowledge. MATERIALS AND METHODS Ten computed tomographic (CT) scans of aortic aneurysm previously treated with the fenestrated endovascular repair were selected to 3D-print aortic templates and elastic vessel phantoms. Two vascular surgeons performed fenestrations using the 3D template and modification plan based on CT measurements. Two operators each performed 10 fenestrated stent-grafts in the aortic template and 10 using CT measurements, for a total of 40 fenestrated stent-grafts. Then, stent-grafts were implanted in elastic vessel phantoms, which served to evaluate fenestration alignment with the target vessel. The alignment was judged in a 5-point scale: 0%, 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100%. The distances between fenestrations served to calculate interobserver variability for both methods. The measurements were processed as interclass correlation coefficient (ICC), Pearson and Spearman correlation, and Bland-Altman plots. RESULTS PMSG created with a 3D template had higher interclass correlation coefficient values and Pearson/Spearman correlation than fenestrations created from CT measurements. The rate of fenestration alignment with the target vessel was higher for PMSG created with a 3D template (p=0.007). CONCLUSIONS PMSGs created with a 3D template are more reliable and have better fenestration alignment with the target vessel than PMSGs created based on CT measurements.
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Affiliation(s)
- Pawel Rynio
- Department of Vascular Surgery, Pomeranian Medical University in Szczecin, Szczecin, Poland
| | - Piotr Gutowski
- Department of Vascular Surgery, Pomeranian Medical University in Szczecin, Szczecin, Poland
| | - Arkadiusz Kazimierczak
- Department of Vascular Surgery, Pomeranian Medical University in Szczecin, Szczecin, Poland
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Jordano L, Robinson EC, Mirza A, Skeik N, Stanberry L, Manunga J. Effects of Iliac Tortuosity Index on Fenestrated Endovascular Aortic Aneurysm Repair for Pararenal and Thoracoabdominal Aortic Aneurysms. J Endovasc Ther 2023:15266028231172375. [PMID: 37154503 DOI: 10.1177/15266028231172375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
PURPOSE To evaluate the effect of iliac tortuosity on procedural metrics and outcomes of patients with complex aortic aneurysms (cAAs) undergoing repair with fenestrated/branched endografts (f/b-EVAR [endovascular aortic aneurysm repair]). MATERIAL AND METHODS The study is a single-center, retrospective review of a prospectively maintained database of patients undergoing aneurysm repair using f/b-EVAR between the years 2013 and 2020 at our institution. Included patients had at least 1 preoperative computed tomography angiography (CTA) available for analysis. Iliac artery tortuosity index (TI) was calculated using centerline of flow imaging from a 3-dimensional work station based on the formula: (centerline iliac artery length / straight-line iliac artery length). The associations between iliac artery tortuosity and procedural metrics, including total operative time, fluoroscopy time, radiation dose, contrast volume, and estimated blood loss (EBL), were evaluated. RESULTS During this period, 219 patients with cAAs underwent f/b-EVAR at our institution. Ninety-one patients (74% men; mean age = 75.2±7.7 years) met criteria for inclusion into the study. In this group, there were 72 (79%) juxtarenal or paravisceral aneurysms and 18 (20%) thoracoabdominal aortic aneurysms and 5 patients (5.4%) with failed previous EVAR. The average aneurysm diameter was 60.1±0.74 mm. Overall, 270 vessels were targeted, and 267 (99%) were successfully incorporated, including 25 celiac arteries, 67 superior mesenteric arteries, and 175 renal arteries. The mean total operative time was 236±83 minutes, fluoroscopy time was 87±39 minutes, contrast volume was 81±47 mL, radiation dose 3246±2207 mGy, and EBL was 290±409 mL. The average left and right TIs for all patients were 1.5±0.3 and 1.4±0.3, respectively. On multivariable analysis, the interval estimates suggest positive association between TI and procedural metrics to a certain degree. CONCLUSIONS In the current series, we found no definitive association between iliac artery TI and procedural metrics, including operative time, contrast used, EBL, fluoroscopy time, and dose in patients undergoing cAA repair using f/b-EVAR. However, there was a trend toward association between TI and all these metrics on multivariable analysis. This potential association needs to be evaluated in a larger series. CLINICAL IMPACT Iliac artery tortuosity should not exclude patients with complex aortic aneurysms from being offered fenestrated or branched stent graft repair. However, special considerations should be taken to mitigate the impact of access tortuosity on alignment of fenestrations with target vessels, including use of extra stiff wires, through and through access and delivering the fenestrated/branched device into another (larger) sheath such as a Gore DrySeal in patients with arteries large enough to accommodate such sheaths.
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Affiliation(s)
- Lia Jordano
- Section of Vascular and Endovascular Surgery of Vascular Surgery, Allina Health Minneapolis Heart Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
| | - Emilie C Robinson
- Section of Vascular and Endovascular Surgery of Vascular Surgery, Allina Health Minneapolis Heart Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
| | | | - Nedaa Skeik
- Section of Vascular and Endovascular Surgery of Vascular Surgery, Allina Health Minneapolis Heart Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
- Minneapolis Heart Institute Foundation, Minneapolis, MN, USA
| | | | - Jesse Manunga
- Section of Vascular and Endovascular Surgery of Vascular Surgery, Allina Health Minneapolis Heart Institute, Abbott Northwestern Hospital, Minneapolis, MN, USA
- Minneapolis Heart Institute Foundation, Minneapolis, MN, USA
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Shahbazian N, Doyle MG, Forbes TL, Amon CH. A modeling framework for computational simulations of thoracic endovascular aortic repair. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3578. [PMID: 35107881 DOI: 10.1002/cnm.3578] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/29/2022] [Indexed: 05/12/2023]
Abstract
Thoracic endovascular aortic repair (TEVAR) is a minimally invasive treatment for thoracic aortic conditions including aneurysms and is associated with a number of postoperative stent graft related complications. Computational simulations of TEVAR have the potential to predict surgical outcomes and complications preoperatively. When using simulations for stent graft design and prediction of complications in a population, it is difficult to generalize patient-specific TEVAR computational models due to patient variability. This study proposes a novel modeling framework for creating realistic population-based computational models of TEVAR focused on aneurysms that allow for developing various clinically relevant geometric configurations and scenarios that are not easily attainable with limited patient data. The framework includes a methodology for developing population-based thoracic aortic geometries and defining age-dependent aortic tissue material models, as well as detailed steps and boundary conditions for finite element modeling of stent graft deployment during TEVAR. The simulation framework is illustrated for predicting the formation of a bird-beak configuration, a wedge-shaped gap at the proximal end of the deployed stent graft in TEVAR that leads to incomplete seal. A baseline TEVAR simulation model was developed along with three simulations in which the value of aortic curvature, aortic arch angle, or aortic tissue properties varied from the baseline model. Analyzing the length and angle of the bird-beak configuration in each case shows that the bird-beak size is sensitive to different values of the aortic geometry highlighting the importance of using realistic parameter values.
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Affiliation(s)
- Negin Shahbazian
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Matthew G Doyle
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Surgery, Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Thomas L Forbes
- Department of Surgery, Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Cristina H Amon
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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Boumpouli M, Sauvage EL, Capelli C, Schievano S, Kazakidi A. Characterization of Flow Dynamics in the Pulmonary Bifurcation of Patients With Repaired Tetralogy of Fallot: A Computational Approach. Front Cardiovasc Med 2021; 8:703717. [PMID: 34660711 PMCID: PMC8514754 DOI: 10.3389/fcvm.2021.703717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 09/07/2021] [Indexed: 11/18/2022] Open
Abstract
The hemodynamic environment of the pulmonary bifurcation is of great importance for adult patients with repaired tetralogy of Fallot (rTOF) due to possible complications in the pulmonary valve and narrowing of the left pulmonary artery (LPA). The aim of this study was to computationally investigate the effect of geometrical variability and flow split on blood flow characteristics in the pulmonary trunk of patient-specific models. Data from a cohort of seven patients was used retrospectively and the pulmonary hemodynamics was investigated using averaged and MRI-derived patient-specific boundary conditions on the individualized models, as well as a statistical mean geometry. Geometrical analysis showed that curvature and tortuosity are higher in the LPA branch, compared to the right pulmonary artery (RPA), resulting in complex flow patterns in the LPA. The computational analysis also demonstrated high time-averaged wall shear stress (TAWSS) at the outer wall of the LPA and the wall of the RPA proximal to the junction. Similar TAWSS patterns were observed for averaged boundary conditions, except for a significantly modified flow split assigned at the outlets. Overall, this study enhances our understanding about the flow development in the pulmonary bifurcation of rTOF patients and associates some morphological characteristics with hemodynamic parameters, highlighting the importance of patient-specificity in the models. To confirm these findings, further studies are required with a bigger cohort of patients.
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Affiliation(s)
- Maria Boumpouli
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Emilie L. Sauvage
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Claudio Capelli
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Silvia Schievano
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
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Louvelle L, Doyle M, Van Arsdell G, Amon C. The Effect of Geometric and Hemodynamic Parameters on Blood Flow Efficiency in Repaired Tetralogy of Fallot Patients. Ann Biomed Eng 2021; 49:2297-2310. [PMID: 33837495 DOI: 10.1007/s10439-021-02771-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 03/27/2021] [Indexed: 12/27/2022]
Abstract
Surgical repair of Tetralogy of Fallot (TOF) involves a series of steps to remove right ventricular outflow tract and pulmonary artery obstruction. However, the large degree of anatomic variability among preoperative TOF patients may impact the effectiveness of different repair strategies and, subsequently, different geometric modifications for different patients. This study investigates the relationships between geometric and hemodynamic parameters and mechanical energy efficiency for a patient-specific dataset of 16 postoperative TOF repairs, using morphometric and statistical shape analyses, as well as computational fluid dynamics simulations with physiologically-relevant inlet and outlet boundary conditions. Quantitatively, negative correlations were found between the right and left pulmonary artery centerline tract cumulative torsion and energy efficiency (r = - 0.65, p = 0.01, for both). A positive correlation was also found for a statistical shape mode associated with skewing of the geometric sub-regions (r = 0.61, p = 0.01). Qualitatively, medium- and low-efficiency geometries exhibit disturbed flow and much more proximal vortex formation as compared to a high-efficiency geometry. Thus, it is recommended, as much as possible, to both relieve and avoid the introduction of torsion into the patient's anatomy during surgical repair of TOF.
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Affiliation(s)
- Leslie Louvelle
- Institute of Biomedical Engineering, University of Toronto, Toronto, Canada.
| | - Matthew Doyle
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, Toronto, Canada
| | - Glen Van Arsdell
- Division of Cardiac Surgery, University of California Los Angeles, Los Angeles, USA
- Division of Cardiac Surgery, University of Toronto, Toronto, Canada
| | - Cristina Amon
- Institute of Biomedical Engineering, University of Toronto, Toronto, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
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Crawford SA, Doyle MG, Amon CH, Forbes TL. Impact of Insertion Technique and Iliac Artery Anatomy on Fenestrated Endovascular Aneurysm Repair. J Endovasc Ther 2019; 26:797-804. [DOI: 10.1177/1526602819872499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
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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Affiliation(s)
- Sean A. Crawford
- 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
| | - Matthew G. Doyle
- Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Cristina H. Amon
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Thomas L. Forbes
- Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada
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Doyle MG, Crawford SA, Osman E, Hatch J, Tse LW, Amon CH, Forbes TL. Comparison of Qualitative and Quantitative Assessments of Iliac Artery Tortuosity and Calcification. Vasc Endovascular Surg 2019; 53:464-469. [DOI: 10.1177/1538574419858163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction: During endovascular aneurysm repair, the iliac artery typically serves as a conduit for device delivery. The degree of tortuosity and calcification in the iliac artery ultimately determines whether the device can successfully traverse the vessel. These 2 parameters can be assessed using qualitative approaches or calculated using quantitative methods based on the Society for Vascular Surgery (SVS) reporting standards. The objective of this study was to determine whether qualitative methods are sufficient to accurately assess iliac artery tortuosity and calcification by calculating interobserver variability and comparing them to the SVS Reporting Standards. Methods: Three vascular surgeons reviewed preoperative computed tomography scans for 50 patients who underwent fenestrated endovascular aneurysm repair and qualitatively assessed left and right iliac artery tortuosity and calcification. Iliac artery geometries were segmented from these image sets. Tortuosity index and calcification length ratio were calculated and categorized based on the SVS Reporting Standards. Results: Interobserver variability was calculated for the qualitative assessments using interclass correlation coefficients. For tortuosity index, among the 3 observers, good agreement was found for the left iliac artery and fair agreement was found for the right. For calcification length ratio, excellent agreement was found for both iliac arteries. When compared to the quantitative assessment, the qualitative assessments underpredicted tortuosity in 2.3% of cases, matched the quantitative values in 16.7% of cases, and overpredicted tortuosity in 81.0% of cases. The qualitative assessments underpredicted calcification in 46.3% of cases, matched the quantitative values in 49.3% of cases, and overpredicted calcification in 4.3% of cases. Conclusion: Qualitative assessment of iliac artery tortuosity showed fair-to-good interobserver agreement and poor agreement to SVS Reporting Standards. Qualitative assessment of iliac artery calcification showed excellent interobserver agreement and fair agreement to SVS Reporting Standards. These trends should be considered when qualitative reporting methodologies are used.
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Affiliation(s)
- Matthew G. Doyle
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada
| | - Sean A. Crawford
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Elrasheed Osman
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada
| | - Jessica Hatch
- Division of Vascular Surgery and Division of General Surgery, Sunnybrook Health Sciences Centre, Toronto, Canada
| | - Leonard W. Tse
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada
| | - Cristina H. Amon
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Thomas L. Forbes
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada
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Predictive Numerical Simulations of Double Branch Stent-Graft Deployment in an Aortic Arch Aneurysm. Ann Biomed Eng 2019; 47:1051-1062. [PMID: 30706308 DOI: 10.1007/s10439-019-02215-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/18/2019] [Indexed: 01/04/2023]
Abstract
Total endovascular repair of the aortic arch represents a promising option for patients ineligible to open surgery. Custom-made design of stent-grafts (SG), such as the Terumo Aortic® RelayBranch device (DB), requires complex preoperative measures. Accurate SG deployment is required to avoid intraoperative or postoperative complications, which is extremely challenging in the aortic arch. In that context, our aim is to develop a computational tool able to predict SG deployment in such highly complex situations. A patient-specific case is performed with complete deployment of the DB and its bridging stents in an aneurysmal aortic arch. Deviations of our simulation predictions from actual stent positions are estimated based on post-operative scan and a sensitivity analysis is performed to assess the effects of material parameters. Results show a very good agreement between simulations and post-operative scan, with especially a torsion effect, which is successfully reproduced by our simulation. Relative diameter, transverse and longitudinal deviations are of 3.2 ± 4.0%, 2.6 ± 2.9 mm and 5.2 ± 3.5 mm respectively. Our numerical simulations show their ability to successfully predict the DB deployment in complex anatomy. The results emphasize the potential of computational simulations to assist practitioners in planning and performing complex and secure interventions.
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Rommens KL, Estrera AL. Contemporary Management of Aortic Arch Aneurysm. Semin Thorac Cardiovasc Surg 2019; 31:697-702. [DOI: 10.1053/j.semtcvs.2019.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/18/2019] [Indexed: 11/11/2022]
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Crawford SA, Sanford RM, Doyle MG, Wheatcroft M, Amon CH, Forbes TL. Prediction of advanced endovascular stent graft rotation and its associated morbidity and mortality. J Vasc Surg 2018; 68:348-355. [DOI: 10.1016/j.jvs.2017.11.061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/05/2017] [Indexed: 10/18/2022]
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Sanford RM, Crawford SA, Genis H, Doyle MG, Forbes TL, Amon CH. Predicting Rotation in Fenestrated Endovascular Aneurysm Repair Using Finite Element Analysis. J Biomech Eng 2018; 140:2681000. [DOI: 10.1115/1.4040124] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Indexed: 01/20/2023]
Abstract
Fenestrated endovascular aneurysm repair (FEVAR) is a minimally invasive method of abdominal aortic aneurysm (AAA) repair utilized in patients with complex vessel anatomies. Stent grafts (SG) used in this process contain fenestrations within the device that need to be aligned with the visceral arteries upon successful SG deployment. Proper alignment is crucial to maintain blood flow to these arteries and avoid surgical complications. During fenestrated SG deployment, rotation of the SG can occur during the unsheathing process. This leads to misalignment of the vessels, and the fenestrations and is associated with poor clinical outcomes. The aim of this study was to develop a computational model of the FEVAR process to predict SG rotation. Six patient-specific cases are presented and compared with surgical case data. Realistic material properties, frictional effects, deployment methods, and boundary conditions are included in the model. A mean simulation error of 2 deg (range 1–4 deg) was observed. This model was then used to conduct a parameter study of frictional properties to see if rotation could be minimized. This study showed that increasing or decreasing the coefficients of friction (COF) between the sheath and the vessel walls would decrease the amount of rotation observed. Our model accurately predicts the amount of SG rotation observed during FEVAR and can be used as a preoperative planning tool within the surgical workflow.
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Affiliation(s)
- Ryan M. Sanford
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
| | - Sean A. Crawford
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, ON M5G 2C4, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Helen Genis
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Matthew G. Doyle
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Thomas L. Forbes
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Cristina H. Amon
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
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Tasso P, Raptis A, Matsagkas M, Lodi Rizzini M, Gallo D, Xenos M, Morbiducci U. Abdominal aortic aneurysm endovascular repair: profiling post-implantation morphometry and hemodynamics with image-based computational fluid dynamics. J Biomech Eng 2018; 140:2682796. [PMID: 30029263 DOI: 10.1115/1.4040337] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Indexed: 11/08/2022]
Abstract
Endovascular aneurysm repair (EVAR) has disseminated rapidly as an alternative to open surgical repair for the treatment of abdominal aortic aneurysms (AAAs), because of its reduced invasiveness, low mortality and morbidity rate. The effectiveness of the endovascular devices used in EVAR is always at question as postoperative adverse events can lead to re-intervention or to a possible fatal scenario for the circulatory system. Motivated by the assessment of the risks related to thrombus formation, here the impact of two different commercial endovascular grafts on local hemodynamics is explored through 20 image-based computational hemodynamic models of EVAR-treated patients (N=10 per each endograft model). Hemodynamic features, susceptible to promote thrombus formation, such as flow separation and recirculation, are quantitatively assessed and compared with the local hemodynamics established in image-based infrarenal abdominal aortic models of healthy subjects (N=10). The hemodynamic analysis is complemented by a geometrical characterization of the EVAR-induced reshaping of the infrarenal abdominal aortic vascular region. The findings of this study indicate that: (1) the clinically observed propensity to thrombus formation in devices used in EVAR strategies can be explained in terms of local hemodynamics by means of image-based computational hemodynamics approach; (2) reportedly pro-thrombotic hemodynamic structures are strongly correlated with the geometry of the aortoiliac tract postoperatively. In perspective, our study suggests that future clinical follow up studies could include a geometric analysis of the region of the implant, monitoring shape variations that can lead to hemodynamic disturbances of clinical significance.
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Affiliation(s)
- Paola Tasso
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino 10129, Italy
| | - Anastasios Raptis
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina 45500, Greece
| | - Miltiadis Matsagkas
- Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa 41334, Greece
| | - Maurizio Lodi Rizzini
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino 10129, Italy
| | - Diego Gallo
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino 10129, Italy
| | - Michalis Xenos
- Department of Mathematics, University of Ioannina, Ioannina 45500, Greece
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino 10129, Italy
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