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Zhuravleva II, Liashenko MM, Shadanov AA, Sirota DA, Cherniavskiĭ AM. [Quo vadimus? Fundamental problems of developing hybrid prostheses of thoracic aorta]. ANGIOLOGIIA I SOSUDISTAIA KHIRURGIIA = ANGIOLOGY AND VASCULAR SURGERY 2021; 27:103-112. [PMID: 35050254 DOI: 10.33529/angio2021412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This article is a review briefly characterizing the state of the art of hybrid surgery of the thoracic aorta using the frozen elephant trunk technique worldwide and in Russia, also discussing unsolved problems of fundamental science, being key issues in creation of new models of hybrid prostheses of the thoracic aorta. The main attention is paid to the problem of radial stiffness of the stent-graft portion of the prosthesis. Performed is a detailed analysis of the factors influencing this characteristic of the sent graft: shape, size and number of cells of the stent element, thickness of the nitinol wire it is made of, method of edge connection, nitinol properties depending on the alloy grade and methods of thermoforming. It is shown that excessive stiffness leads to the development of d-SINE syndrome. This is followed by discussing the problem of optimal stiffness of stent grafts, based on the design of stent graft elements and elastic properties of the wall of the true channel of a dissecting aortic aneurysm. Also proposed is an approach to solving the problem of d-SINE, consisting in creation of conical stent grafts and/or a gradual decrease of radial stiffness of stent elements in the direction of the distal portion. Comprehensively addressed are disadvantages of the graft portion of the prosthesis, in 95% of items made of polyethylene terephthalate fiber: susceptibility to degradation associated with manufacturing defects and intraoperative microdamages, abrasive effect in the zone of contact with stent elements, partial postoperative hydrolysis and an inflammatory reaction to a foreign body, often being clinically pronounced. Also touched upon are certain aspects of creating hermetic coatings of the graft portion, with the use of vancomycin possessing low cytotoxicity as part of an antibacterial component being promising. As a whole, it is demonstrated that advances in creating a novel generation of hybrid prostheses should be associated with new approaches and materials, to be obtained at the junction of medicine and fundamental sciences.
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Affiliation(s)
- I Iu Zhuravleva
- Department of Aorta and Coronary Arteries Surgery, Laboratory of Bioprosthetics, National Medical Research Centre named after Academician E.N. Meshalkin, RF Ministry of Public Health, Novosibirsk, Russia
| | - M M Liashenko
- Department of Aorta and Coronary Arteries Surgery, Laboratory of Bioprosthetics, National Medical Research Centre named after Academician E.N. Meshalkin, RF Ministry of Public Health, Novosibirsk, Russia
| | - A A Shadanov
- Department of Aorta and Coronary Arteries Surgery, Laboratory of Bioprosthetics, National Medical Research Centre named after Academician E.N. Meshalkin, RF Ministry of Public Health, Novosibirsk, Russia
| | - D A Sirota
- Department of Aorta and Coronary Arteries Surgery, Laboratory of Bioprosthetics, National Medical Research Centre named after Academician E.N. Meshalkin, RF Ministry of Public Health, Novosibirsk, Russia
| | - A M Cherniavskiĭ
- Department of Aorta and Coronary Arteries Surgery, Laboratory of Bioprosthetics, National Medical Research Centre named after Academician E.N. Meshalkin, RF Ministry of Public Health, Novosibirsk, Russia
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CHIANG CHENGHSIEN, HUNG TINKAN, YEH MINGLONG, CHEN WEILING, KAN CHUNGDANN. FIXATION STUDY OF SINGLE AND DOUBLE STENT GRAFTS FOR ENDOVASCULAR AORTIC REPAIR. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519418500549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Application of double-barreled cannon stent grafts aortic repair (DoBAR) was reported in 2011 for extremely large aortic aneurysms of patients when there was no proper size of grafts for the emergent treatment. Fixation characteristics of the double stent grafts are obtained in a laboratory setting, and are incorporated with those of single Zenith TX2 grafts of sizes from 34 to 42[Formula: see text]mm. Radial stress and shear increase linearly with the oversizing parameter but decrease with increasing stent diameter. The slope of the linear relationship is practically the same for this group of grafts. When the original circular stent grafts of diameter 36 and 38[Formula: see text]mm are deformed to form DoBAR of diameter 44 or 46.4[Formula: see text]mm, the formation could provide higher radial stress and shear to secure fixation for endo-aortic repair. The experimental results of single and DoBAR grafts can be incorporated for clinical application of DoBAR for emergent treatment.
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Affiliation(s)
- CHENG-HSIEN CHIANG
- Department of Biomedical Engineering, National Cheng Kung University, No. 1, Daxue Road, East District, Tainan City 701, Taiwan
| | - TIN-KAN HUNG
- Department of Bioengineering, University of Pittsburgh, 700 O’Hara Street, Pittsburgh, PA 15261, USA
| | - MING-LONG YEH
- Department of Biomedical Engineering, National Cheng Kung University, No. 1, Daxue Road, East District, Tainan City 701, Taiwan
| | - WEI-LING CHEN
- Department of Engineering and Maintenance, Kaohsiung Veterans General Hospital, No. 386, Dazhong 1st Road, Zuoying District, Kaohsiung City 81362, Taiwan
| | - CHUNG-DANN KAN
- Division of Cardiovascular Surgery, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138 Sheng-Li Road, Tainan 704, Taiwan
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Tricarico R, He Y, Laquian L, Scali ST, Tran-Son-Tay R, Beck AW, Berceli SA. Hemodynamic and Anatomic Predictors of Renovisceral Stent-Graft Occlusion Following Chimney Endovascular Repair of Juxtarenal Aortic Aneurysms. J Endovasc Ther 2017; 24:880-888. [PMID: 28914135 DOI: 10.1177/1526602817731096] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To identify anatomic and hemodynamic changes associated with impending visceral chimney stent-graft occlusion after endovascular aneurysm repair (EVAR) with the chimney technique (chEVAR). METHODS A retrospective evaluation was performed of computed tomography scans from 41 patients who underwent juxtarenal chEVAR from 2008 to 2012 to identify stent-grafts demonstrating conformational changes following initial placement. Six subjects (mean age 74 years; 3 men) were selected for detailed reconstruction and computational hemodynamic analysis; 4 had at least 1 occluded chimney stent-graft. This subset of repairs was systematically analyzed to define the anatomic and hemodynamic impact of these changes and identify signature patterns associated with impending renovisceral stent-graft occlusion. Spatial and temporal analyses of cross-sectional area, centerline angle, intraluminal pressure, and wall shear stress (WSS) were performed within the superior mesenteric and renal artery chimney grafts used for repair. RESULTS Conformational changes in the chimney stent-grafts and associated perturbations, in both local WSS and pressure, were responsible for the 5 occlusions in the 13 stented branches. Anatomic and hemodynamic signatures leading to occlusion were identified within 1 month postoperatively, with a lumen area <14 mm2 (p=0.04), systolic pressure gradient >25 Pa/mm (p=0.03), and systolic WSS >45 Pa (p=0.03) associated with future chimney stent-graft occlusion. CONCLUSION Chimney stent-grafts at increased risk for occlusion demonstrated anatomic and hemodynamic signatures within 1 month of juxtarenal chEVAR. Analysis of these parameters in the early postoperative period may be useful for identifying and remediating these high-risk stent-grafts.
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Affiliation(s)
- Rosamaria Tricarico
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Yong He
- 2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Liza Laquian
- 3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Salvatore T Scali
- 2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Roger Tran-Son-Tay
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.,4 Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Adam W Beck
- 5 University of Alabama School of Medicine, Birmingham, AL, USA
| | - Scott A Berceli
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.,2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
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Roy D, Lerouge S, Inaekyan K, Kauffmann C, Mongrain R, Soulez G. Experimental validation of more realistic computer models for stent-graft repair of abdominal aortic aneurysms, including pre-load assessment. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02769. [PMID: 26748474 DOI: 10.1002/cnm.2769] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 12/30/2015] [Accepted: 01/04/2016] [Indexed: 06/05/2023]
Abstract
Although the endovascular repair of abdominal aortic aneurysms is a less invasive alternative than classic open surgery, complications such as endoleak and kinking still need to be addressed. Numerical simulation of endovascular repair is becoming a valuable tool in stent-graft (SG) optimization, patient selection and surgical planning. The experimental and numerical forces required to produce SG deformations were compared in a range of in vivo conditions in the present study. The deformation modes investigated were: bending as well as axial, transversal and radial compressions. In particular, an original method was developed to efficiently account for radial pre-load because of the pre-compression of stents to match the graft dimensions during manufacturing. This is important in order to compute the radial force exerted on the vessel after deployment more accurately. Variations of displacement between the experimental and numerical results ranged from 1.39% for simple leg bending to 5.93% for three-point body bending. Finally, radial pre-load was modeled by increasing Young's modulus of each stent. On average, it was found that Young's modulus had to be augmented by a factor of 2. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- David Roy
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada, H2X 0A9
- Biomedical Engineering Institute, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
| | - Sophie Lerouge
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada, H2X 0A9
- Department of Mechanical Engineering, École de Technologie Supérieure, Montréal, Québec, Canada, H3C 1K3
- Department of Radiology, Radio-Oncology and Nuclear Medicine, Université de Montréal, Montréal, Québec, Canada, H3C 3J7
| | - Karina Inaekyan
- Department of Mechanical Engineering, École de Technologie Supérieure, Montréal, Québec, Canada, H3C 1K3
| | - Claude Kauffmann
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada, H2X 0A9
| | - Rosaire Mongrain
- Department of Mechanical Engineering, McGill University, Montréal, Québec, Canada, H3A 0C3
| | - Gilles Soulez
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada, H2X 0A9
- Biomedical Engineering Institute, Université de Montréal, Montréal, Québec, Canada, H3T 1J4
- Department of Radiology, Radio-Oncology and Nuclear Medicine, Université de Montréal, Montréal, Québec, Canada, H3C 3J7
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Chiang CH, Yeh ML, Chen WL, Kan CD. Apparatus for Comparison of Pullout Forces for Various Thoracic Stent Grafts at Varying Neck Angulations and Oversizes. Ann Vasc Surg 2015; 31:196-204. [PMID: 26597245 DOI: 10.1016/j.avsg.2015.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/07/2015] [Accepted: 10/11/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND The purpose of this study is to provide an apparatus for comparison of pullout forces for various thoracic stent grafts at varying neck angulations and oversizes. METHODS An in vitro platform capable of performing pullout tests was used on stent grafts in angulated silicone tubes designed for this study (0°, 45°, 90°, and 135° with a 32-mm inner diameter) in a temperature-controlled chamber (37 ± 2°C). Three commercial stent grafts with sizes commonly used in Taiwan (Valiant: 34, 36, 38, and 40 mm; Zenith TX2: 34, 36, 38, and 40 mm; and TAG: 34, 37, and 40 mm) were used, and each size was tested 8 times for each angulation condition. RESULTS The mean dislodgement forces (DFs) at 0° angulation within 10-20% oversize were approximately 22.7, 9.6, and 9.0 N for the Valiant, Zenith TX2, and TAG devices, respectively, whereas the mean DFs decreased by 46%, 38%, and 50% to 12.3, 5.9, and 4.5 N when the angulation reached 135°. Regression analysis shows that neck angulation was a significant factor for the Valiant and Zenith TX2 devices (P < 0.0001 and P < 0.0001, respectively) but not for the TAG device (P = 0.483). In addition, oversize and interactions between variables (angulation × oversize) exhibited significant effects on the DFs for all devices (P < 0.0001). CONCLUSIONS We successfully built up an apparatus for comparison of pullout forces for various thoracic stent grafts at varying neck angulations and oversizes. With the empirical comparative data of different brand stent grafts under various conditions shown and compared, our findings suggest that aortic neck angulation has a negative correlation with stent-graft fixation. To have better stent-graft fixation and seal in the aortic arch for thoracic endovascular aortic repair, a longer landing zone with cautiously selected oversize is a more suitable selection.
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Affiliation(s)
- Cheng-Hsien Chiang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Ming-Long Yeh
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Ling Chen
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Chung-Dann Kan
- Division of Cardiovascular Surgery, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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Callanan A, Davis N, McGloughlin T, Walsh M. The effects of stent interaction on porcine urinary bladder matrix employed as stent-graft materials. J Biomech 2014; 47:1885-93. [DOI: 10.1016/j.jbiomech.2014.02.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 11/28/2013] [Accepted: 02/27/2014] [Indexed: 11/16/2022]
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Scali ST, Feezor RJ, Chang CK, Waterman AL, Berceli SA, Huber TS, Beck AW. Critical analysis of results after chimney endovascular aortic aneurysm repair raises cause for concern. J Vasc Surg 2014; 60:865-73; discussion 873-5. [PMID: 24816514 DOI: 10.1016/j.jvs.2014.03.295] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/23/2014] [Indexed: 12/17/2022]
Abstract
OBJECTIVE "Chimney" techniques used to extend landing zones for endovascular aortic repair (chEVAR) have been increasingly reported; however, concerns about durability and patency remain. The purpose of this analysis was to examine midterm outcomes of chEVAR. METHODS All patients at the University of Florida treated with chEVAR were reviewed. Major adverse events (MAEs) were recorded and defined as any chimney stent thrombosis, type Ia endoleak in follow-up, reintervention, 30-day/in-hospital death, or ≥25% decrease in estimated glomerular filtration rate after discharge. Primary end points included chimney stent patency and freedom from MAE. Secondary end points included complications and long-term survival. RESULTS From 2008 to 2012, 41 patients (age ± standard deviation, 73 ± 8 years; male, 66% [n = 27]) were treated with a total of 76 chimney stents (renal, n = 51; superior mesenteric artery, n = 16; celiac artery, n = 9) for a variety of indications: juxtarenal, 42% (n = 17, one rupture), suprarenal, 17% (n = 7), and thoracoabdominal aneurysm, 17% (n = 7); aortic anastomotic pseudoaneurysm, 15% (n = 6; three ruptures); type Ia endoleak after EVAR, 7% (n = 3); and atheromatous disease, 2% (n = 1). Two patients had a single target vessel abandoned because of cannulation failure, and one had a type Ia endoleak at case completion (technical success, 93%). Intraoperative complications occurred in seven patients (17%), including graft maldeployment with unplanned mesenteric chimney (n = 2) and access vessel injury requiring repair (n = 5). Major postoperative complications developed in 20% (n = 8). The 30-day mortality and in-hospital mortality were 5% (n = 2) and 7% (n = 3), respectively. At median follow-up of 18.2 months (range, 1.4-41.5 months), 28 of 33 patients (85%) with available postoperative imaging experienced stabilization or reduction of abdominal aortic aneurysm sac diameters. Nine patients (32%) developed endoleak at some point during follow-up (type Ia, 7% [n = 3]; type II, 10% [n = 4]; indeterminate, 7% [n = 3]), and one patient underwent open, surgical conversion. The estimated probability of freedom from reintervention (±standard error mean) was 96% ± 4% at both 1 year and 3 years. Primary patency of all chimney stents was 88% ± 5% and 85% ± 5% at 1 year and 3 years, respectively. Corresponding freedom from MAEs was 83% ± 7% and 57% ± 10% at 1 year and 3 years. The actuarial estimated survival for all patients at 1 year and 5 years was 85% ± 6% and 65% ± 8%, respectively. CONCLUSIONS These results demonstrate that chEVAR can be completed with a high degree of success; however, perioperative complications and MAEs during follow-up, including loss of chimney patency and endoleak, may occur at a higher rate than previously reported. Elective use of chEVAR should be performed with caution, and comparison to open and fenestrated EVAR is needed to determine long-term efficacy of this technique.
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Affiliation(s)
- Salvatore T Scali
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla.
| | - Robert J Feezor
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Catherine K Chang
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Alyson L Waterman
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Scott A Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Thomas S Huber
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Adam W Beck
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
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CHEN ZENGSHENG, ZHANG YAN, YAO ZHAOHUI, XU SHANGDONG, ZHANG XIWEN. EXPERIMENTAL RESEARCH OF THE PRESSURE REDUCTION ON AAA WALL BY THE INSERTION OF A STENT GRAFT. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The purpose of this study was to investigate the influence of stent grafts on the wall pressure of aneurysms and find out what kind of stent graft is suitable for curing aneurysm. A set of experiment apparatus that simulated the human heart and artery was set up, including an elastic abdominal aortic aneurysm (AAA) model which was made of rubber. The influence of healing induced by stent grafts with different diameters and either permeable or impermeable on the AAA were investigated by comparing experiments using the AAA model with clinical stent grafts in a pulsatile flow system that simulated human blood circulation. The experiment results show that the pressure on the AAA wall reduced after the insertion of a stent graft. The permeable stent graft is not propitious to the pressure reduction. Furthermore, the reduction of pressure is related to stent graft diameter, that is, stent grafts whose diameter is 10–15% larger than the arterial diameter leads to the optimal reduction of the wall pressure. The results are unprecedented and expected to have significant clinical applications.
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Affiliation(s)
- ZENGSHENG CHEN
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, P. R. China
| | - YAN ZHANG
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, P. R. China
| | - ZHAOHUI YAO
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, P. R. China
| | - SHANGDONG XU
- Institute of Heart, Pulmonary and Vascular Diseases, Beijing Anzhen Hospital, Beijing 100029, P. R. China
| | - XIWEN ZHANG
- Department of Engineering Mechanics, School of Aerospace, Tsinghua University, Beijing 100084, P. R. China
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Scali ST, Feezor RJ, Huber TS, Beck AW. Acute bilateral renal artery chimney stent thrombosis after endovascular repair of a juxtarenal abdominal aortic aneurysm. J Vasc Surg 2013; 61:1058-61. [PMID: 24246538 DOI: 10.1016/j.jvs.2013.10.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 09/26/2013] [Accepted: 10/01/2013] [Indexed: 11/20/2022]
Abstract
The use of "chimney" stents to augment the proximal landing zone for endovascular aneurysm repair has been increasingly reported. Despite mounting enthusiasm for this technique, the durability of this type of repair and capability to preserve perfusion to target branches remains a paramount concern. Here, we report management of a patient presenting with acute bilateral renal chimney stent thrombosis and a type Ia endoleak.
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Affiliation(s)
- Salvatore T Scali
- Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, Fla.
| | - Robert J Feezor
- Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, Fla
| | - Thomas S Huber
- Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, Fla
| | - Adam W Beck
- Division of Vascular Surgery and Endovascular Therapy, University of Florida College of Medicine, Gainesville, Fla
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von Sachsen S, Senf B, Burgert O, Meixensberger J, Florek HJ, Mohr FW, Etz CD. Stent graft visualization and planning tool for endovascular surgery using finite element analysis. Int J Comput Assist Radiol Surg 2013; 9:617-33. [PMID: 24170574 DOI: 10.1007/s11548-013-0943-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 09/03/2013] [Indexed: 11/26/2022]
Abstract
PURPOSE A new approach to optimize stent graft selection for endovascular aortic repair is the use of finite element analysis. Once the finite element model is created and solved, a software module is needed to view the simulation results in the clinical work environment. A new tool for interpretation of simulation results, named Medical Postprocessor, that enables comparison of different stent graft configurations and products was designed, implemented and tested. METHODS Aortic endovascular stent graft ring forces and sealing states in the vessel landing zone of three different configurations were provided in a surgical planning software using the Medical Imaging Interaction Tool Kit (MITK) software system. For data interpretation, software modules for 2D and 3D presentations were implemented. Ten surgeons evaluated the software features of the Medical Postprocessor. These surgeons performed usability tests and answered questionnaires based on their experience with the system. RESULTS The Medical Postprocessor visualization system enabled vascular surgeons to determine the configuration with the highest overall fixation force in 16+/-6 s, best proximal sealing in 56+/-24s and highest proximal fixation force in 38+/- s. The majority considered the multiformat data provided helpful and found the Medical Postprocessor to be an efficient decision support system for stent graft selection. The evaluation of the user interface results in an ISONORM-conform user interface (113.5 points). CONCLUSION The Medical Postprocessor visualization software tool for analyzing stent graft properties was evaluated by vascular surgeons. The results show that the software can assist the interpretation of simulation results to optimize stent graft configuration and sizing.
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Affiliation(s)
- S von Sachsen
- Innovation Center Computer Assisted Surgery (ICCAS), University of Leipzig, Leipzig, Germany,
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Prasad A, Xiao N, Gong XY, Zarins CK, Figueroa CA. A computational framework for investigating the positional stability of aortic endografts. Biomech Model Mechanobiol 2013; 12:869-87. [PMID: 23143353 PMCID: PMC3638896 DOI: 10.1007/s10237-012-0450-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 10/19/2012] [Indexed: 10/27/2022]
Abstract
Endovascular aneurysm repair (Greenhalgh in N Engl J Med 362(20):1863-1871, 2010) techniques have revolutionized the treatment of thoracic and abdominal aortic aneurysm disease, greatly reducing the perioperative mortality and morbidity associated with open surgical repair techniques. However, EVAR is not free of important complications such as late device migration, endoleak formation and fracture of device components that may result in adverse events such as aneurysm enlargement, need for long-term imaging surveillance and secondary interventions or even death. These complications result from the device inability to withstand the hemodynamics of blood flow and to keep its originally intended post-operative position over time. Understanding the in vivo biomechanical working environment experienced by endografts is a critical factor in improving their long-term performance. To date, no study has investigated the mechanics of contact between device and aorta in a three-dimensional setting. In this work, we developed a comprehensive Computational Solid Mechanics and Computational Fluid Dynamics framework to investigate the mechanics of endograft positional stability. The main building blocks of this framework are: (1) Three-dimensional non-planar aortic and stent-graft geometrical models, (2) Realistic multi-material constitutive laws for aorta, stent, and graft, (3) Physiological values for blood flow and pressure, and (4) Frictional model to describe the contact between the endograft and the aorta. We introduce a new metric for numerical quantification of the positional stability of the endograft. Lastly, in the results section, we test the framework by investigating the impact of several factors that are clinically known to affect endograft stability.
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Affiliation(s)
- Anamika Prasad
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Nan Xiao
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Biomedical Engineering, King’s College London, London SE1 7EH, UK
| | - Xiao-Yan Gong
- Medical Implant Mechanics LLC, 26895 Aliso Creek Road, Aliso Viejo, CA 92656, USA
| | | | - C. Alberto Figueroa
- Department of Biomedical Engineering, King’s College London, London SE1 7EH, UK
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Stefanov F, McGloughlin T, Delassus P, Morris L. Hemodynamic variations due to spiral blood flow through four patient-specific bifurcated stent graft configurations for the treatment of abdominal aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:179-196. [PMID: 23255342 DOI: 10.1002/cnm.2525] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 09/18/2012] [Accepted: 10/07/2012] [Indexed: 06/01/2023]
Abstract
Endovascular repair is now a recognised procedure for treating abdominal aortic aneurysms. However, post-operative complications such as stent graft migration and thrombus may still occur. To assess these complications numerically, the correct input boundary conditions, which include the full human aorta with associated branching, should be included. Four patient-specific computed tomography scanned bifurcated stent grafts (SGs) were modelled and attached onto a full human aorta, which included the ascending, aortic arch and descending aortas. Two of the SG geometries had a twisted leg configuration, while the other two had conventional nontwisted leg configurations. Computational fluid dynamics was completed for both geometries and the hemodynamics assessed. The complexity of the flow patterns and secondary flows were influenced by the inclusion of the full human aorta at the SG proximal section. During the decelerating phase significant recirculations occurred along the main body of all SG configurations. The inclusion of the full human aorta did not impact the velocity contours within the distal legs and there was no difference in drag forces with the SG containing the full human aorta and those without. A twisted leg configuration further promoted a spiral flow formation along its distal legs.
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Affiliation(s)
- Florian Stefanov
- Galway Medical Technologies Centre-GMedTech, Department of Mechanical and Industrial Engineering, Galway Mayo Institute of Technology, Galway, Ireland
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Callanan A, Morris LG, McGloughlin TM. Finite element and photoelastic modelling of an abdominal aortic aneurysm: a comparative study. Comput Methods Biomech Biomed Engin 2012; 15:1111-9. [DOI: 10.1080/10255842.2011.574618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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