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Korte J, Marsh LMM, Saalfeld S, Behme D, Aliseda A, Berg P. Fusiform versus Saccular Intracranial Aneurysms-Hemodynamic Evaluation of the Pre-Aneurysmal, Pathological, and Post-Interventional State. J Clin Med 2024; 13:551. [PMID: 38256685 PMCID: PMC11154261 DOI: 10.3390/jcm13020551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Minimally-invasive therapies are well-established treatment methods for saccular intracranial aneurysms (SIAs). Knowledge concerning fusiform IAs (FIAs) is low, due to their wide and alternating lumen and their infrequent occurrence. However, FIAs carry risks like ischemia and thus require further in-depth investigation. Six patient-specific IAs, comprising three position-identical FIAs and SIAs, with the FIAs showing a non-typical FIA shape, were compared, respectively. For each model, a healthy counterpart and a treated version with a flow diverting stent were created. Eighteen time-dependent simulations were performed to analyze morphological and hemodynamic parameters focusing on the treatment effect (TE). The stent expansion is higher for FIAs than SIAs. For FIAs, the reduction in vorticity is higher (Δ35-75% case 2/3) and the reduction in the oscillatory velocity index is lower (Δ15-68% case 2/3). Velocity is reduced equally for FIAs and SIAs with a TE of 37-60% in FIAs and of 41-72% in SIAs. Time-averaged wall shear stress (TAWSS) is less reduced within FIAs than SIAs (Δ30-105%). Within this study, the positive TE of FDS deployed in FIAs is shown and a similarity in parameters found due to the non-typical FIA shape. Despite the higher stent expansion, velocity and vorticity are equally reduced compared to identically located SIAs.
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Affiliation(s)
- Jana Korte
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, 39106 Magdeburg, Germany
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany; (L.M.M.M.); (S.S.); (D.B.); (P.B.)
| | - Laurel M. M. Marsh
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany; (L.M.M.M.); (S.S.); (D.B.); (P.B.)
- Department of Mechanical Engineering, George Mason University, Fairfax, VA 22030, USA
| | - Sylvia Saalfeld
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany; (L.M.M.M.); (S.S.); (D.B.); (P.B.)
- Department of Computer Science and Automation, Ilmenau University of Technology, 98693 Ilmenau, Germany
| | - Daniel Behme
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany; (L.M.M.M.); (S.S.); (D.B.); (P.B.)
- University Hospital Magdeburg, University of Magdeburg, 39106 Magdeburg, Germany
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA;
| | - Philipp Berg
- Research Campus STIMULATE, University of Magdeburg, 39106 Magdeburg, Germany; (L.M.M.M.); (S.S.); (D.B.); (P.B.)
- Department of Medical Engineering, University of Magdeburg, 39106 Magdeburg, Germany
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2
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Williamson PN, Docherty PD, Yazdi SG, Khanafer A, Kabaliuk N, Jermy M, Geoghegan PH. Review of the Development of Hemodynamic Modeling Techniques to Capture Flow Behavior in Arteries Affected by Aneurysm, Atherosclerosis, and Stenting. J Biomech Eng 2022; 144:1128816. [PMID: 34802061 DOI: 10.1115/1.4053082] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Indexed: 02/05/2023]
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death in the developed world. CVD can include atherosclerosis, aneurysm, dissection, or occlusion of the main arteries. Many CVDs are caused by unhealthy hemodynamics. Some CVDs can be treated with the implantation of stents and stent grafts. Investigations have been carried out to understand the effects of stents and stent grafts have on arteries and the hemodynamic changes post-treatment. Numerous studies on stent hemodynamics have been carried out using computational fluid dynamics (CFD) which has yielded significant insight into the effect of stent mesh design on near-wall blood flow and improving hemodynamics. Particle image velocimetry (PIV) has also been used to capture behavior of fluids that mimic physiological hemodynamics. However, PIV studies have largely been restricted to unstented models or intra-aneurysmal flow rather than peri or distal stent flow behaviors. PIV has been used both as a standalone measurement method and as a comparison to validate the CFD studies. This article reviews the successes and limitations of CFD and PIV-based modeling methods used to investigate the hemodynamic effects of stents. The review includes an overview of physiology and relevant mechanics of arteries as well as consideration of boundary conditions and the working fluids used to simulate blood for each modeling method along with the benefits and limitations introduced.
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Affiliation(s)
- Petra N Williamson
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Paul D Docherty
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Sina G Yazdi
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Adib Khanafer
- Vascular, Endovascular, and Renal Transplant Unit, Christchurch Hospital, Canterbury District Health Board, Riccarton Avenue, Christchurch 8053, New Zealand; Christchurch School of Medicine, University of Otago, Dunedin 9016, New Zealand
| | - Natalia Kabaliuk
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Mark Jermy
- Department of Mechanical Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Patrick H Geoghegan
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK; Department of Mechanical and Industrial Engineering, University of South Africa, Johannesburg 2006, South Africa
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Kühn AL, Gounis MJ, Puri AS. Introduction: History and Development of Flow Diverter Technology and Evolution. Neurosurgery 2019; 86:S3-S10. [DOI: 10.1093/neuros/nyz307] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/15/2019] [Indexed: 11/12/2022] Open
Abstract
AbstractThe introduction of flow diverter technology to the field of neurointervention has revolutionized the treatment of intracranial aneurysms. The therapy approach has shifted from intrasaccular aneurysm treatment to exclusion of the aneurysm from the blood circulation with remodeling of the parent artery. Previously, “difficult”-to-treat aneurysms including fusiform and blister aneurysms, but also aneurysms arising from a diseased vessel segment, can now be safely and permanently treated with flow diverters. A little over a decade ago, after extensive bench testing and refinement of the flow diverter concept, the device was eventually available for clinical use and today it has become a standard treatment for intracranial aneurysms. Currently, United States Food and Drug Administration (FDA)-approved flow diverters are the Pipeline Embolization Device (Medtronic) and the Surpass Streamline Flow Diverter (Stryker). The devices can either be delivered or deployed via a standard femoral artery approach or a radial artery approach. Other considerations for catheter setup and device deployment strategies depending on aneurysm location or vessel anatomy are described.
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Affiliation(s)
- Anna Luisa Kühn
- Division of Neuroradiology, Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Matthew J Gounis
- Division of Neuroimaging and Intervention, New England Center for Stroke Research, Department of Radiology, University of Massachusetts Medical Center, Worcester, Massachusetts
| | - Ajit S Puri
- Division of Neuroimaging and Intervention, New England Center for Stroke Research, Department of Radiology, University of Massachusetts Medical Center, Worcester, Massachusetts
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Ho WH, Tshimanga IJ, Ngoepe MN, Jermy MC, Geoghegan PH. Evaluation of a Desktop 3D Printed Rigid Refractive-Indexed-Matched Flow Phantom for PIV Measurements on Cerebral Aneurysms. Cardiovasc Eng Technol 2019; 11:14-23. [PMID: 31820351 PMCID: PMC7002330 DOI: 10.1007/s13239-019-00444-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 11/20/2019] [Indexed: 12/24/2022]
Abstract
PURPOSE Fabrication of a suitable flow model or phantom is critical to the study of biomedical fluid dynamics using optical flow visualization and measurement methods. The main difficulties arise from the optical properties of the model material, accuracy of the geometry and ease of fabrication. METHODS Conventionally an investment casting method has been used, but recently advancements in additive manufacturing techniques such as 3D printing have allowed the flow model to be printed directly with minimal post-processing steps. This study presents results of an investigation into the feasibility of fabrication of such models suitable for particle image velocimetry (PIV) using a common 3D printing Stereolithography process and photopolymer resin. RESULTS An idealised geometry of a cerebral aneurysm was printed to demonstrate its applicability for PIV experimentation. The material was shown to have a refractive index of 1.51, which can be refractive matched with a mixture of de-ionised water with ammonium thiocyanate (NH4SCN). The images were of a quality that after applying common PIV pre-processing techniques and a PIV cross-correlation algorithm, the results produced were consistent within the aneurysm when compared to previous studies. CONCLUSIONS This study presents an alternative low-cost option for 3D printing of a flow phantom suitable for flow visualization simulations. The use of 3D printed flow phantoms reduces the complexity, time and effort required compared to conventional investment casting methods by removing the necessity of a multi-part process required with investment casting techniques.
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Affiliation(s)
- W H Ho
- Department of Mechanical and Industrial Engineering, University of South Africa, Johannesburg, South Africa.,School of Mechanical Aerospace and Industrial Engineering, University of the Witwatersrand, Johannesburg, South Africa
| | - I J Tshimanga
- Department of Mechanical and Industrial Engineering, University of South Africa, Johannesburg, South Africa
| | - M N Ngoepe
- Department of Mechanical Engineering, University of Cape Town, Cape Town, South Africa
| | - M C Jermy
- Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
| | - P H Geoghegan
- Department of Mechanical and Industrial Engineering, University of South Africa, Johannesburg, South Africa. .,Biomedical Engineering, School of Life and Health Sciences, Aston University, Birmingham, England.
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Rautio R, Sinisalo M, Helmiö P. Endovascular treatment of extradural internal carotid artery aneurysm with a flow diverter stent. Acta Radiol Open 2019; 8:2058460119872404. [PMID: 31516735 PMCID: PMC6724490 DOI: 10.1177/2058460119872404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 08/07/2019] [Indexed: 11/16/2022] Open
Abstract
Extradural internal carotid artery aneurysms are rare and the indications for treatment are not well defined. We report successful management of two high extradural internal carotid artery aneurysms treated with flow diverter stents. The endovascular repair of extradural internal carotid artery aneurysms is effective because with surgical treatment there is always the possibility of cranial nerve injury.
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Affiliation(s)
- Riitta Rautio
- Department of Interventional Radiology, Turku University Hospital, Finland
| | - Matias Sinisalo
- Department of Interventional Radiology, Turku University Hospital, Finland
| | - Päivi Helmiö
- Department of Vascular Surgery, Turku University Hospital, Finland
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6
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CFD-Based Comparison Study of a New Flow Diverting Stent and Commercially-Available Ones for the Treatment of Cerebral Aneurysms. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9071341] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Flow-diverting stents (FDSs) show considerable promise for the treatment of cerebral aneurysms by diverting blood flow away from the aneurysmal sacs, however, post-treatment complications such as failure of occlusion and subarachnoid haemorrhaging remain and vary with the FDS used. Based on computational fluid dynamics (CFD), this study aimed to investigate the performance of a new biodegradable stent as compared to two metallic commercially available FDSs. CFD models were developed for an idealized cerebral artery with a sidewall aneurysmal sac treated by deploying the aforementioned stents of different porosities (90, 80, and 70 % ) respectively. By using these models, the simulation and analysis were performed, with a focus on comparing the local hemodynamics or the blood flow in the stented arteries as compared to the one without the stent deployment. For the comparison, we computed and compared the flow velocity, wall shear stress (WSS) and pressure distributions, as well as the WSS related indices, all of which are of important parameters for studying the occlusion and potential rupture of the aneurysm. Our results illustrate that the WSS decreases within the aneurysmal sac on the treated arteries, which is more significant for the stents with lower porosity or finer mesh. Our results also show that the maximum WSS near the aneurysmal neck increases regardless of the stents used. In addition, the WSS related indices including the time-average WSS, oscillatory shear index and relative residence time show different distributions, depending on the FDSs. Together, we found that the finer mesh stents provide more flow reduction and smaller region characterized by high oscillatory shear index, while the new stent has a higher relative residence time.
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Yazdi SG, Geoghegan PH, Docherty PD, Jermy M, Khanafer A. A Review of Arterial Phantom Fabrication Methods for Flow Measurement Using PIV Techniques. Ann Biomed Eng 2018; 46:1697-1721. [DOI: 10.1007/s10439-018-2085-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/25/2018] [Indexed: 12/21/2022]
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Alkhalili K, Hannallah J, Cobb M, Chalouhi N, Philips JL, Echeverria AB, Jabbour P, Babiker MH, Frakes DH, Gonzalez LF. The Effect of Stents in Cerebral Aneurysms: A Review. Asian J Neurosurg 2018; 13:201-211. [PMID: 29682009 PMCID: PMC5898080 DOI: 10.4103/1793-5482.175639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The etiology of up to 95% of cerebral aneurysms may be accounted for by hemodynamically-induced factors that create vascular injury. The purpose of this review is to describe key physical properties that stents have and how they affect cerebral aneurysms. We performed a two-step screening process. First, a structured search was performed using the PubMed database. The following search terms and keywords were used: “Hemodynamics,” “wall shear stress (WSS),” “velocity,” “viscosity,” “cerebral aneurysm,” “intracranial aneurysm,” “stent,” “flow diverter,” “stent porosity,” “stent geometry,” “stent configuration,” and “stent design.” Reports were considered if they included original data, discussed hemodynamic changes after stent-based treatment of cerebral aneurysms, examined the hemodynamic effects of stent deployment, and/or described the geometric characteristics of both stents and the aneurysms they were used to treat. The search strategy yielded a total of 122 articles, 61 were excluded after screening the titles and abstracts. Additional articles were then identified by cross-checking reference lists. The final collection of 97 articles demonstrates that the geometric characteristics and configurations of deployed stents influenced hemodynamic parameters such as aneurysmal WSS, inflow, and pressure. The geometric characteristics of the aneurysm and its position also had significant influences on intra-aneurysmal hemodynamics after treatment. In conclusion, changes in specific aneurysmal hemodynamic parameters that result from stenting relate to a number of factors including the geometric properties and configurations of deployed stents, the geometric properties of the aneurysm, and the pretreatment hemodynamics.
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Affiliation(s)
- Kenan Alkhalili
- Department of Surgery, University of Arizona, Tucson, Arizona, USA
| | - Jack Hannallah
- Department of Surgery, University of Arizona, Tucson, Arizona, USA
| | - Mary Cobb
- Division of Neurosurgery, Duke University, Durham, NC, USA
| | - Nohra Chalouhi
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jessica L Philips
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Pascal Jabbour
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - David H Frakes
- Division of Neurosurgery, Duke University, Durham, NC, USA
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Waseem A, Ahmed I, Hadeel S. Endovascular Management of Microcerebral Aneurysms with Diameter Smaller than 3 mm: Is It Feasible and Safe? J Stroke Cerebrovasc Dis 2018; 27:1590-1598. [PMID: 29475583 DOI: 10.1016/j.jstrokecerebrovasdis.2018.01.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 01/07/2018] [Accepted: 01/12/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The neurosurgical management of microcerebral aneurysms with diameter smaller than 3 mm remains a great challenge as many complications can occur. AIM Our target was to assess the efficacy and usefulness of endovascular treatment of these lesions. METHODS We did a prospective and retrospective gathering of the results of endovascular treatments for a group of 16 patients with 16 microcerebral aneurysms. Four patients were treated by direct coil embolization, and 12 patients were managed by remodeling techniques. RESULTS Coil embolization was technically accessible in all cases. Initial complete occlusion is achieved in 12 patients. We did not face major technical complications such as aneurysmal rupture or coil migration during the endovascular management in 15 patients. Only in 1 case the second and last coil (2⁄1 mm) migrated distally and could not be retrieved. In this case clinical evidence of neurologic deterioration and weakness in left lower limb due to right anterior cerebral artery territory stroke was evidenced in the follow-up computed tomography scan. Follow-up clinical and radiological studies were available for 9 of 12 surviving patients and showed complete occlusion in 7 cases, and in 1 case aneurysm tiny recanalization was demonstrated after 1 year, which was retreated with complete occlusion, and in another case tiny aneurysm recanalization at the neck appeared after 2 years, which was left under observation. CONCLUSIONS Endovascular treatment is a beneficial and effective therapeutic alternative to microsurgery for microaneurysms. The long-term assessment of endovascular management for these lesions was not included in that study.
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Affiliation(s)
- Aziz Waseem
- Department of Neurosurgery, Alexandria University School of Medicine, Alexandria, Egypt; Tawam Hospital, Abu Dhabi, United Arab Emirates.
| | - Ismael Ahmed
- Department of Neurosurgery, Alexandria University School of Medicine, Alexandria, Egypt
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10
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Yeow SL, Leo HL. Is Multiple Overlapping Uncovered Stents Technique Suitable for Aortic Aneurysm Repair? Artif Organs 2017; 42:174-183. [DOI: 10.1111/aor.12993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/23/2017] [Accepted: 06/14/2017] [Indexed: 01/22/2023]
Affiliation(s)
- Siang Lin Yeow
- Division of Research; Singapore General Hospital; Singapore
- Biomedical Engineering; National University of Singapore; Singapore
| | - Hwa Liang Leo
- Biomedical Engineering; National University of Singapore; Singapore
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11
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Influence of overlapping pattern of multiple overlapping uncovered stents on the local mechanical environment: A patient-specific parameter study. J Biomech 2017; 60:188-196. [PMID: 28712543 DOI: 10.1016/j.jbiomech.2017.06.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/05/2017] [Accepted: 06/25/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Multiple overlapping uncovered stents (MOUS) system has shown potentials in managing complex aortic aneurysms with side branches involvement. It promotes the development of thrombus by modulating local flow pattern that reduces the wall tension, while maintaining patency of side branches. However the modulation of local hemodynamic parameters depends on various factors that have not been assessed comprehensively. METHODS Aneurysm 3D geometry was reconstructed based on CT images. One-way fluid-structure interaction analysis was performed to quantify structural stress concentration in the wall, and changes of blood velocity, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT) and pressure in the sac due to the stent deployment. RESULTS High structural stress concentration due to stent deployment was found in the landing zone and it increased linearly with the number of stents deployed. The wall tension in the sac was unaffected by the stent deployment. Stress within the wall was insensitive to the different overlapping pattern. After one stent was deployed, the mean flow velocity in the sac reduced by 36.4%. The deployment of the 2nd stent further reduced the mean sac velocity by 10%. WSS decreased while both OSI and RRT increased after stent deployment, however pressure in the sac remained nearly unchanged. Except for the cases with complete stents struts alignment, different overlapping pattern had little effect on flow parameters. CONCLUSIONS Mechanical parameters modulated by the MOUS are insensitive to different overlapping pattern suggesting that endovascular procedure can be performed with less attention to the overlapping pattern.
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Sotelo J, Urbina J, Valverde I, Mura J, Tejos C, Irarrazaval P, Andia ME, Hurtado DE, Uribe S. Three-dimensional quantification of vorticity and helicity from 3D cine PC-MRI using finite-element interpolations. Magn Reson Med 2017; 79:541-553. [DOI: 10.1002/mrm.26687] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/01/2017] [Accepted: 03/05/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Julio Sotelo
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Structural and Geotechnical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Jesús Urbina
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
| | - Israel Valverde
- Pediatric Cardiology Unit; Hospital Virgen del Rocio; Sevilla Spain
- Cardiovascular Pathology Unit; Institute of Biomedicine of Seville (IBIS), Hospital Virgen del Rocio; Sevilla Spain
| | - Joaquín Mura
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Cristián Tejos
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Pablo Irarrazaval
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Electrical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Marcelo E. Andia
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Daniel E. Hurtado
- Department of Structural and Geotechnical Engineering; Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
| | - Sergio Uribe
- Biomedical Imaging Center; Pontificia Universidad Católica de Chile; Santiago Chile
- Department of Radiology; School of Medicine, Pontificia Universidad Católica de Chile; Santiago Chile
- Institute for Biological and Medical Engineering; Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile; Santaigo Chile
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Lee K, Park H, Park I, Park SQ, Kwon OK, Han J. Y-configuration Stent-assisted Coil Embolization for Wide-necked Intracranial Bifurcation Aneurysms. J Cerebrovasc Endovasc Neurosurg 2017; 18:355-362. [PMID: 28184345 PMCID: PMC5298977 DOI: 10.7461/jcen.2016.18.4.355] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/25/2016] [Accepted: 12/20/2016] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE The objective of this study was to determine the efficiency and safety of Y configuration stent-assisted coiling with double-closed stents for wide-necked intracranial aneurysms located at arterial bifurcations thorough analysis of a multicenter case series. MATERIALS AND METHODS A retrospective chart review was done on 10 patients who underwent endovascular treatment of wide-necked intracranial aneurysms with Y-configuration stent-assisted coil embolization in three centers from August 2011 to March 2014. The degree of aneurysmal occlusion was assessed using the Raymond scale. Clinical outcomes were assessed before operation, at discharge, and at the last follow-up visit using the Glasgow outcome scale. RESULTS The 10 patients included 6 females and 4 males with a mean age of 58.6 years. Indications for treatment included 6 unruptured intracranial aneurysms and 4 ruptured intracranial aneurysms. Five aneurysms were located at the basilar artery bifurcation, four aneurysms were located in an anterior communicating artery, and one aneurysm was in the pericallosal artery. The mean size of the 10 aneurysms was 9.7 mm. All aneurysms had a dome-to-neck ratio of < 1.5 (mean, 0.89). Immediate complications included one thromboembolic event out of the 10 cases. Immediate posttreatment angiograms showed complete occlusion in 1 aneurysm and residual necks in 9 aneurysms. Follow-up results showed 8 complete occlusions and 2 residual necks. No delayed complications were observed during the follow-up period (mean: 20 months). CONCLUSION Y configuration using double-closed cell stents is feasible and safe in selected patients. This method is an acceptable option for managing complex wide-necked bifurcations.
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Affiliation(s)
- Kwangho Lee
- Department of Neurosurgery, Gyeongsang National University School of Medicine and Gyeongsang National, University Hospital, Jinju, Korea
| | - Hyun Park
- Department of Neurosurgery, Gyeongsang National University School of Medicine and Gyeongsang National, University Hospital, Jinju, Korea
| | - Insung Park
- Department of Neurosurgery, Gyeongsang National University School of Medicine and Gyeongsang National, University Hospital, Jinju, Korea.; Department of Neurosurgery, College of Medicine, Gyeongsang National University and Institute of Health, Sciences, Jinju, Korea
| | - Sukh Que Park
- Department of Neurosurgery, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul, Korea
| | - O-Ki Kwon
- Department of Neurosurgery, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Jongwoo Han
- Department of Neurosurgery, Gyeongsang National University School of Medicine and Gyeongsang National, University Hospital, Jinju, Korea
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14
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Dholakia R, Sadasivan C, Fiorella DJ, Woo HH, Lieber BB. Hemodynamics of Flow Diverters. J Biomech Eng 2017; 139:2569375. [DOI: 10.1115/1.4034932] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Indexed: 01/17/2023]
Abstract
Cerebral aneurysms are pathological focal evaginations of the arterial wall at and around the junctions of the circle of Willis. Their tenuous walls predispose aneurysms to leak or rupture leading to hemorrhagic strokes with high morbidity and mortality rates. The endovascular treatment of cerebral aneurysms currently includes the implantation of fine-mesh stents, called flow diverters, within the parent artery bearing the aneurysm. By mitigating flow velocities within the aneurysmal sac, the devices preferentially induce thrombus formation in the aneurysm within hours to days. In response to the foreign implant, an endothelialized arterial layer covers the luminal surface of the device over a period of days to months. Organization of the intraneurysmal thrombus leads to resorption and shrinkage of the aneurysm wall and contents, eventually leading to beneficial remodeling of the pathological site to a near-physiological state. The devices' primary function of reducing flow activity within aneurysms is corollary to their mesh structure. Complete specification of the device mesh structure, or alternately device permeability, necessarily involves the quantification of two variables commonly used to characterize porous media—mesh porosity and mesh pore density. We evaluated the flow alteration induced by five commercial neurovascular devices of varying porosity and pore density (stents: Neuroform, Enterprise, and LVIS; flow diverters: Pipeline and FRED) in an idealized sidewall aneurysm model. As can be expected in such a model, all devices substantially reduced intraneurysmal kinetic energy as compared to the nonstented case with the coarse-mesh stents inducing a 65–80% reduction whereas the fine-mesh flow diverters induced a near-complete flow stagnation (∼98% reduction). We also note a trend toward greater device efficacy (lower intraneurysmal flow) with decreasing device porosity and increasing device pore density. Several such flow studies have been and are being conducted in idealized as well as patient-derived geometries with the overarching goals of improving device design, facilitating treatment planning (what is the optimal device for a specific aneurysm), and predicting treatment outcome (will a specific aneurysm treated with a specific device successfully occlude over the long term). While the results are generally encouraging, there is poor standardization of study variables between different research groups, and any consensus will only be reached after standardized studies are conducted on collectively large datasets. Biochemical variables may have to be incorporated into these studies to maximize predictive values.
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Affiliation(s)
- Ronak Dholakia
- Department of Neurological Surgery, Stony Brook University Medical Center, Stony Brook, NY 11794
| | - Chander Sadasivan
- Department of Neurological Surgery, Stony Brook University Medical Center, Stony Brook, NY 11794
| | - David J. Fiorella
- Department of Neurological Surgery, Stony Brook University Medical Center, Stony Brook, NY 11794
| | - Henry H. Woo
- Department of Neurological Surgery, Stony Brook University Medical Center, Stony Brook, NY 11794
| | - Baruch B. Lieber
- Professor Department of Neurological Surgery, Stony Brook University Medical Center, HSC T12, Room 080, 100 Nicolls Road, Stony Brook, NY 11794-8122 e-mail:
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Zhang M, Anzai H, Chopard B, Ohta M. Towards the patient-specific design of flow diverters made from helix-like wires: an optimization study. Biomed Eng Online 2016; 15:159. [PMID: 28155683 PMCID: PMC5260143 DOI: 10.1186/s12938-016-0257-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Flow diverter (FD) intervention is an emerging endovascular technique for treating intracranial aneurysms. High flow-diversion efficiency is desired to accelerate thrombotic occlusion inside the aneurysm; however, the risk of post-stenting stenosis in the parent artery is posed when flow-diversion efficiency is pursued by simply decreasing device porosity. For improving the prognosis of FD intervention, we develop an optimization method for the design of patient-specific FD devices that maintain high levels of porosity. Methods An automated structure optimization method for FDs with helix-like wires was developed by applying a combination of lattice Boltzmann fluid simulation and simulated annealing procedure. Employing intra-aneurysmal average velocity as the objective function, the proposed method tailored the wire structure of an FD to a given vascular geometry by rearranging the starting phase of the helix wires. Results FD optimization was applied to two idealized (S and C) vascular models and one realistic (R) model. Without altering the original device porosity of 80%, the flow-reduction rates of optimized FDs were improved by 5, 2, and 28% for the S, C, and R models, respectively. Furthermore, the aneurysmal flow patterns after optimization exhibited marked alterations. We confirmed that the disruption of bundle of inflow is of great help in blocking aneurysmal inflow. Axial displacement tests suggested that the optimal FD implanted in the R model possesses good robustness to tolerate uncertain axial positioning errors. Conclusions The optimization method developed in this study can be used to identify the FD wire structure with the optimal flow-diversion efficiency. For a given vascular geometry, custom-designed FD structure can maximally reduce the aneurysmal inflow with its porosity maintained at a high level, thereby lowering the risk of post-stenting stenosis. This method facilitates the study of patient-specific designs for FD devices.
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Affiliation(s)
- Mingzi Zhang
- Graduate School of Engineering, Tohoku University, Katahira 2-1-1, Aoba, Sendai, Miyagi, 9808577, Japan
| | - Hitomi Anzai
- Frontier Research Institute for Interdisciplinary Science, Tohoku University, Katahira 2-1-1, Aoba, Sendai, Miyagi, 9808577, Japan
| | - Bastien Chopard
- CUI, Department d'Informatique, University of Geneva, 7 route de Drize, 1227, Carouge, Switzerland
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba, Sendai, Miyagi, 9808577, Japan.
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Castellan L, Causin F, Perini S. Trattamento endovascolare degli aneurismi intracranici mediante stent. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/1971400903016sp121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- L. Castellan
- Istituto di Neuroradiologia, Ospedale S. Bortolo, Vicenza
| | - F. Causin
- Istituto di Neuroradiologia, Ospedale S. Bortolo, Vicenza
| | - S. Perini
- Istituto di Neuroradiologia, Ospedale S. Bortolo, Vicenza
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Reconstructive Endovascular Treatment of Spontaneous Symptomatic Large or Giant Vertebrobasilar Dissecting Aneurysms: Clinical and Angiographic Outcomes. Clin Neuroradiol 2014; 26:291-300. [PMID: 25540817 DOI: 10.1007/s00062-014-0369-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/17/2014] [Indexed: 12/20/2022]
Abstract
PURPOSE To investigate the clinical and angiographic outcomes of spontaneous symptomatic large or giant vertebrobasilar dissecting aneurysms (VBDAs) following reconstructive endovascular treatment (EVT) with stent(s). METHODS We retrospectively identified 21 patients with spontaneous symptomatic large or giant VBDAs who had been treated with reconstructive EVT between September 2009 and September 2013 in our department. There were 20 men and 1 woman, with a mean age of 46.5 years (range: 17-67 years). Clinical and angiographic data were reviewed and evaluated. RESULTS Reconstructive EVT with sole stenting (SS, 10 cases) or stent-assisted coiling (SAC, 11 cases) technique was technically feasible in all cases. Angiographic follow-up results confirmed delayed thrombosis of the aneurysm sac in only two of the eight cases after SS, and recurrence of the aneurysm sac in six of the nine cases after SAC. Postoperative complications or poor neurologic outcomes occurred in seven cases (33.3 %). Three patients died after SS, including postoperative subarachnoid hemorrhage in one case and pulmonary embolism in one case. The other patient died soon after SAC, without radiologic result to confirm the causes of death. Other adverse events after treatment include ischemic complication in two cases, intramural hemorrhage in one case, aggravation of initial mass effect in one case. As to the other 14 cases, the post-procedural processes were uneventful and no complication was observed. The condition of them was improved in seven cases (33.3 %), and unchanged in seven cases (33.3 %) during follow-up. CONCLUSIONS Reconstructive EVT with traditional intracranial stent(s) for the treatment of large and giant VBDAs carries a high failure rate and substantial risk of complications. The outcome of treating these difficult lesions with traditional intracranial stenting seems questionable and unpredictable.
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Zhang Y, Teng Z, Lu Q, Zhao Z, Bao J, Feng X, Feng R, Chen Z, Huang Y, Sadat U, Gillard JH, Jing Z. Management of complicated aortic aneurysms using multiple overlapping uncovered stents: mid-term outcome from a cohort study. Medicine (Baltimore) 2014; 93:e209. [PMID: 25501077 PMCID: PMC4602789 DOI: 10.1097/md.0000000000000209] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
This study sought to report the mid-term outcome of a modified flow-diverting strategy in the treatment of complicated aortic aneurysms of different morphology. Historical data suggested aortic aneurysm expansion and rupture after endovascular treatment with current commercial flow-diverters, indicating the essentiality of further investigation of this technique prior to its large-scale clinical application. An alternative flow-diverting strategy using layer-by-layer assembled multiple overlapping uncovered stents was employed in this study. The treatment outcome in aneurysms of different morphology (saccular, fusiform, and dissecting) was assessed during a mid-term follow-up period.Of 42 patients enrolled in this study (30 male, mean age: 63.3 years), technical success was achieved in 40 cases. During an average follow-up period of 20.9 months, mean aneurysm diameter shrunk from 53.4 ± 13.6 mm to 48.8 ± 13.9 mm (P < 0.001), while stent-induced sac thrombosis ratio increased significantly (18.1 ± 14.9% to 93.6 ± 9.5%, P < 0.001). The majority of side branches (74/76 major visceral branches, 237/244 minor segmental arteries), covered by 3.3 stents on average, maintained their patency after stenting. Saccular aneurysms manifested the highest thrombus deposition speed (18/20 were totally thrombosed within 12 months) and most significant shrinkage (51.4 ± 13.3 mm pre-operatively vs 43.5 ± 10.2 mm during follow-up, P < 0.001) compared with fusiform and dissecting aneurysms. This modified flow-diverting strategy could be a feasible alternative in the management of complicated aortic aneurysms where vital branches need to be preserved. The treatment outcome may depend on the aneurysm type. Further studies with larger patient cohort and longer follow-up are required to substantiate these results.
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Affiliation(s)
- Yongxue Zhang
- From the Division of Vascular Surgery, Changhai Hospital, Shanghai, China (YZ, QL, ZZ, JB, XF, RF); University Department of Radiology, University of Cambridge, UK (YZ, ZT, YH, JHG); Department of Engineering, University of Cambridge, UK (ZT); School of Aerospace, Tsinghua University, Beijing, China (ZC); Cambridge Vascular Unit, Addenbrooke's Hospital, Cambridge, UK (US); and Military Institute of Vascular Disease, the First Affiliated Hospital of Second Military Medical University, Shanghai, China (ZJ)
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Lee CJ, Srinivas K, Qian Y. Three-dimensional hemodynamic design optimization of stents for cerebral aneurysms. Proc Inst Mech Eng H 2014; 228:213-24. [DOI: 10.1177/0954411914523405] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Flow-diverting stents occlude aneurysms by diverting the blood flow from entering the aneurysm sac. Their effectiveness is determined by the thrombus formation rate, which depends greatly on stent design. The aim of this study was to provide a general framework for efficient stent design using design optimization methods, with a focus on stent hemodynamics as the starting point. Kriging method was used for completing design optimization. Three different cases of idealized stents were considered, and 40–60 samples from each case were evaluated using computational fluid dynamics. Using maximum velocity and vorticity reduction as objective functions, the optimized designs were identified from the samples. A number of optimized stent designs have been found from optimization, which revealed that a combination of high pore density and thin struts is desired. Additionally, distributing struts near the proximal end of aneurysm neck was found to be effective. The success of the methods and framework devised in this study offers a future possibility of incorporating other disciplines to carry out multidisciplinary design optimization.
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Affiliation(s)
- Chang-Joon Lee
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
| | - Karkenahalli Srinivas
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
| | - Yi Qian
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
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20
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Kim YJ, Ko JH. Sole stenting with large cell stents for very small ruptured intracranial aneurysms. Interv Neuroradiol 2014; 20:45-53. [PMID: 24556299 DOI: 10.15274/inr-2014-10007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 09/08/2013] [Indexed: 11/12/2022] Open
Abstract
A flow-diverting stent such as the Pipeline embolization device (PED, ev3 Endovascular, Plymouth, MN, USA) and Silk flow-diverting stent (Balt Extrusion, Montmorency, France) offers an acceptable alternative for the treatment of difficult aneurysms according to their morphologies, including giant, wide-necked, fusiform, and blister types. However, complications arising from the use of these stents have frequently been reported including several cases of branch artery occlusion and delayed occlusion of the stented parent vessel shortly after antiplatelet medications were discontinued, highlighting the potential need for long-term antiplatelet therapy, and disastrous bleeding complications in unruptured aneurysm. In addition, these microcell stents are difficult to use in distal aneurysms located over the ICA bifurcation and basilar tip because of the stiffness of the device, and perforating vessel occlusion is more likely to occur due to the characteristics of the stent. Before the era of flow-diverting microcell stents, large cell intracranial stents like the Neuroform stent (Boston Scientific/Target Therapeutic, Fremont, CA, USA) and Enterprise stent (Cordis Neurovascular, Miami, FL, USA) without coiling were used to provide flow-diverting effects for complex intracranial aneurysms. Sole stenting has been used even in cases of ruptured aneurysm, with patients on different antiplatelet medications. However, no single endovascular institute has embraced sole stenting using large cell intracranial stents as a systemized treatment for ruptured intracranial aneurysms. Here we designed this study to evaluate the possibility of safely treating very small aneurysms using one or two stents without coiling during the period of subarachnoid hemorrhage (SAH). This retrospective study was conducted with eight patients who had rupture of very small intracranial aneurysms (less than 3 mm in size). All were treated using the Neuroform and the Enterprise stents; there was single stenting in five, in-stent telescopic stenting in two, and Y-configured stenting in one. The angiographic results with clinical outcomes were collected and analyzed. Complete aneurysm obliteration was observed in three cases, and size reduction or stable angiographic findings was found in five cases on the last follow-up angiography. No growing aneurysm or rebleeding was found on any follow-up angiography. Thromboembolic complications were found in one patient. It is difficult to make conclusions on the long-term efficacy of this technique with such a small number of cases, however sole stenting with a large cell intracranial stent for the treatment of very small aneurysms may be used safely as an alternative treatment even during an episode of SAH.
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Affiliation(s)
- Young-Joon Kim
- Department of Neurosurgery, Dankook University College of Medicine; Cheonan, Republic of Korea -
| | - Jung Ho Ko
- Department of Neurosurgery, Dankook University College of Medicine; Cheonan, Republic of Korea
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Li C, Li Y, Jiang C, Wu Z, Wang Y, Yang X. Stent alone treatment for dissections and dissecting aneurysms involving the basilar artery. J Neurointerv Surg 2014; 7:50-5. [DOI: 10.1136/neurintsurg-2013-010967] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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22
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Lam AKN, Ko MWL, Leung LKK, Kwok JCK, Yuen MMF, Lam DCC. Characterization of pressure reduction in coil-filled aneurysm under flow of human blood with and without anti-coagulant. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:739-42. [PMID: 24109793 DOI: 10.1109/embc.2013.6609606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Filling aneurysms with embolization coils is a widely used part of the treatment to stop intracranial aneurysm from rupturing. However, the effect of coiling on aneurysmal pressure has not been established. In this study, the effect of intra-aneurysmal coiling on pressure reduction was characterized. Coil deployment in the aneurysm will disturb flow and may induce aneurysmal coagulation. These effects were experimentally examined in this study using silicone rubber saccular aneurysm models. Changes in aneurysmal blood pressure under pulsatile flow were characterized. With coils in the aneurysm, results showed that flow reduction of anti-coagulated blood in the aneurysm did not reduce aneurysmal pressure. Significant pressure reduction was observed only when the blood's coagulation ability is restored to normal. These results suggest that blood coagulation is pivotal to pressure reduction and concomitant with rupture risk reduction in treatments of aneurysm with coils.
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Darsaut TE, Bing F, Makoyeva A, Gevry G, Salazkin I, Raymond J. Flow diversion to treat aneurysms: the free segment of stent. J Neurointerv Surg 2013; 5:452-7. [PMID: 22782844 DOI: 10.1136/neurintsurg-2012-010451] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
PURPOSE Flow diverters (FDs) have led to spectacular results in otherwise untreatable aneurysm cases, but complications can occur. There is a pressing need to study factors that might predict their safety and efficacy. METHODS The anatomical constraints that may impact on the ability of FDs to redirect blood flow and provide a scaffold for neointima formation across the aneurysm or branch ostia are explored and classified. A nomenclature is needed to identify the key factors that should be taken into account before contemplating the use of FDs in clinical aneurysms, and that should be reproduced in experimental models, if they are to guide safe clinical use. RESULTS The free stent segment (FSS), the portion of the device that covers an aneurysm or branch origin, dictates whether aneurysms or branches will remain patent. Three levels of increasing complexity must be taken into account to anticipate what will occur at the FSS level. (1) Virtual models can provide basic principles; (2) in vitro studies allow testing FSS deformations that may occur in various anatomical circumstances and impact on efficacy and safety; (3) but only in vivo studies can provide key information on neointimal closure following implantation that will differentiate success from failure. CONCLUSIONS A nomenclature is necessary to determine the optimal or suboptimal conditions for FDs and to design the virtual, in vitro and in vivo studies that will allow a better understanding of the factors involved in the success or failure of this novel treatment.
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Affiliation(s)
- Tim E Darsaut
- Department of Surgery, Division of Neurosurgery, Mackenzie Health Sciences Centre, University of Alberta Hospital, Edmonton, Alberta, Canada
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24
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Ohta M, Fujimura N, Augsburger L, Barath K, Yilmaz H, Abdo G, Lovblad KO, Rüfenacht DA. Subtracted vortex centers path line method with cinematic angiography for measurement of flow speed in cerebral aneurysms. Neurol Res 2013; 30:251-5. [PMID: 17803843 DOI: 10.1179/016164107x230658] [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] [Indexed: 10/31/2022]
Abstract
BACKGROUND AND PURPOSE The assessment of blood flow speed by imaging modalities is of increasing importance for endovascular treatment, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) utilizes image post-processing for determining flow quantitatively. In current practice, intra-aneurysmal flow in an in vitro model is visualized by laser sheet translumination and digitally recorded. In this study, we applied this method to cinematic angiography (CA), which is the preferred imaging method for endovascular interventions, to analyse hemodynamic changes. The SVC method was applied to the images and compared with results of the slipstream line method with colored fluid. METHODS A transparent tubular model was constructed of silicone which included an aneurysm 10 mm in diameter and having a 5 mm neck on a straight parent artery with a diameter of 3.5 mm. The model was integrated into a pulsatile circulation system. By CA, successive images at 25 frames/s with injection of contrast were obtained. RESULTS AND CONCLUSION Rotating vortexes of contrast, which advanced along the wall of the aneurysm, were observed in successive images of the aneurysm cavity. This phenomenon was also observed in the successive images with the slipstream line method. The speed of the vortex center was calculated and the results show that the vortex speed of CA was the same as that under the slipstream line method. This indicates the possibility of applying the SVC method to medical imaging equipment for analysis of the flow in aneurysms containing stent.
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Affiliation(s)
- Makoto Ohta
- Biofluid Control laboratory, Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan.
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Baráth K, Cassot F, Fasel JHD, Ohta M, Rüfenacht DA. Influence of stent properties on the alteration of cerebral intra-aneurysmal haemodynamics: flow quantification in elastic sidewall aneurysm models. Neurol Res 2013; 27 Suppl 1:S120-8. [PMID: 16197837 DOI: 10.1179/016164105x35477] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES Stent implantation across the neck of cerebral aneurysms may induce intra-aneurysmal flow reduction, and consequently saccular thrombosis and vessel wall repair. To analyse the influence of different stent parameters on such flow reduction, we studied the flow changes in vascular models, induced by a series of stents. METHODS Two different neck-sized elastic sidewall aneurysm models were connected to a circulatory loop. Twenty different stents were introduced in both models to analyse the effect of their parameters, such as porosity, filament diameter and permeability. Flow patterns were visualized by using glass particles and laser sheet translumination. The digitally recorded data were transferred for computer analysis. The changes of the vortex velocity for each stent model combination were investigated and statistically evaluated. RESULTS Intra-aneurysmal flow analysis showed dispersion of the vortices of a variable degree, and velocity reduction of 30% mean in model 1 and 49% mean in model 2. By statistical analysis three groups of stents ('best', 'medium', 'worst') were identified, according to their haemodynamic efficacy. No correlations were observed between the haemodynamic performance of the stents and the porosity, filament diameter and permeability values separately. The stent effects were on average more important in the large-necked than in the small-necked aneurysm model. DISCUSSION Stent implantation induces intra-aneurysmal loss of vortex coherence and flow reduction. The analysed stent parameters show complex interrelationship, including also stent 'design'. The difference in the haemodynamic efficacy of the individual stents between the two models raises the question of 'stent positioning effects'.
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Affiliation(s)
- Krisztina Baráth
- Department of Radiology, University Hospital of Geneva, Geneva, Switzerland.
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Lee JI, Ko JK, Lee TH, Choi CH, Lee SW, Cho WH. Sole stenting technique for the treatment of uncoilable very small aneurysms in the intracranial internal carotid artery. Neurol Med Chir (Tokyo) 2013; 53:310-7. [PMID: 23708222 DOI: 10.2176/nmc.53.310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The treatment of very small aneurysms with diameter of less than 3 mm remains a challenge for both endovascular and surgical treatment. Endovascular treatment of these lesions may be difficult and is associated with a high risk of complications because of their small size. The present study evaluated the safety, feasibility, and efficacy of the endovascular treatment using sole stenting technique for uncoilable very small aneurysms of the intracranial internal carotid artery (ICA). From August 2004 through January 2010, eight very small aneurysms of intracranial ICA in eight patients were treated with endovascular sole stenting technique. All very small aneurysms were ruptured (n = 3) or aneurysms associated with another ruptured (n = 2) and unruptured aneurysms (n = 3) in the same artery. Stents were Neuroform and balloon expandable coronary stents. Stent deployment was carried out without difficulty in all patients. Single stent deployment was done for six aneurysms, and double stents in two aneurysms. The immediate angiographic results were partial occlusion in one case and no occlusion in seven cases. One direct carotid-cavernous fistula occurred during coronary stenting without permanent neurological deficit. No neurological deterioration or hemorrhagic complication was seen during the follow-up period in seven patients. Follow-up angiography (mean 9 months) was available in six patients and revealed complete occlusion in four and no occlusion in two cases. Sole stenting technique may be a feasible and effective therapeutic alternative for uncoilable very small aneurysms. The long-term efficacy and durability of stenting for these lesions remains to be determined in a large series.
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Affiliation(s)
- Jae Il Lee
- Department of Neurosurgery, Pusan National University Hospital, Medical Research Institute, Busan, Republic of Korea
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Comparison of Enterprise With Neuroform Stent-Assisted Coiling of Intracranial Aneurysms. AJR Am J Roentgenol 2013; 200:872-8. [PMID: 23521463 DOI: 10.2214/ajr.12.8954] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Tang AYS, Chan HN, Tsang ACO, Leung GKK, Leung KM, Yu ACH, Chow KW. The effects of stent porosity on the endovascular treatment of intracranial aneurysms located near a bifurcation. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jbise.2013.68099] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wu YF, Yang PF, Shen J, Huang QH, Zhang X, Qian Y, Liu JM. A comparison of the hemodynamic effects of flow diverters on wide-necked and narrow-necked cerebral aneurysms. J Clin Neurosci 2012; 19:1520-4. [PMID: 22704947 DOI: 10.1016/j.jocn.2011.10.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/26/2011] [Accepted: 10/29/2011] [Indexed: 11/27/2022]
Affiliation(s)
- Yong-Fa Wu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, 168 Changhai Road, Shanghai 200433, China
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Hemodynamics of cerebral aneurysms: computational analyses of aneurysm progress and treatment. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:782801. [PMID: 22454695 PMCID: PMC3290806 DOI: 10.1155/2012/782801] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 11/10/2011] [Indexed: 12/02/2022]
Abstract
The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment.
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Effects of metal coverage rate of flow diversion device on neointimal growth at side branch ostium and stented artery: an animal experiment in rabbit abdominal aorta. Neuroradiology 2011; 54:849-55. [PMID: 22170078 DOI: 10.1007/s00234-011-0984-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 11/21/2011] [Indexed: 10/14/2022]
Abstract
INTRODUCTION To access the effect of actual metal coverage rate (MCR) on neointimal growth at covered side branch ostium and stented artery after implantation of a flow diversion device. METHODS Flow diverters (FDs) were implanted into abdominal aortas of 20 New Zealand rabbits. Four weeks and three months after FD implantation, the patency of side branches covered by the devices was assessed by angiography. The animals were sacrificed after angiography at 3 months postsurgery. The local actual MCR was measured under microscope and calculated. The extent of neointimal coverage at the ostia of branches and the neointima within the stent were examined by histology and scanning electron microscopy. RESULTS No side branch occlusion was noted, either immediately after implantation or at follow-ups. At 3 months after implantation, the intimal coverage of branch ostia caused by a 30-40% MCR was not significantly different from that caused by an MCR ≤ 30% (p = 0.792), but it was significantly lower than that caused by an MCR ≥ 40% (p = 0.021). Neointimal thickness in the stented abdominal aorta was positively correlated to MCR (r = 0.523, p = 0.001). The neointima was composed predominantly of smooth muscle cells and collagen fibers. CONCLUSION The actual MCR exhibited remarkable differences once FD was implanted in vivo. Significantly more intimal coverage at the side branch ostia could be induced when MCR was ≥40%. The neointimal thickness within the stent was positively correlated to device MCR.
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Huang QH, Wu YF, Xu Y, Hong B, Zhang L, Liu JM. Vascular geometry change because of endovascular stent placement for anterior communicating artery aneurysms. AJNR Am J Neuroradiol 2011; 32:1721-5. [PMID: 21816920 DOI: 10.3174/ajnr.a2597] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Hemodynamics have been shown to play an important role in the initiation and progress of intracranial aneurysms, and are considered well-related to vascular configuration. The purpose of this study was to quantify the vascular geometry change due to intracranial stent placement and to discuss its potential effects on hemodynamics. MATERIALS AND METHODS Imaging data of patients with wide-neck AcomA aneurysms, treated with stent-assisted coiling between January 2005 and January 2010, were retrospectively analyzed. The angle between the afferent vessels (A1 segment) and the efferent vessels (ipsilateral or contralateral A2 segment) was calculated to determine the exact change in the angle after stent placement. RESULTS In all 20 patients, the stent caused a distinct change in the geometry of the parent vessel. Stent-related vascular angle change ranged from 7.60 to 74.88°, with an average of 29.95°. In 10 cases, the angle changed by >30°. In the 12 patients with the distal segment of the stent placed in the ipsilateral A2 segment, the mean postoperative A1-A2 angle increased by 27.71 ± 13.17° (from 7.60° to 48.29°). In the other 8 patients with the distal segment of the stent placed in the contralateral A2 segment, the mean postoperative A1-AcomA-A2 angle increased by 33.29 ± 21.89°(from 15.49° to 74.88°). CONCLUSIONS In addition to serving as a scaffold to contain coils, stent placement for AcomA aneurysms has a substantial effect on the vascular geometry, which may result in local hemodynamic changes.
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Affiliation(s)
- Q-H Huang
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, China
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Cekirge HS, Yavuz K, Geyik S, Saatci I. A novel "Y" stent flow diversion technique for the endovascular treatment of bifurcation aneurysms without endosaccular coiling. AJNR Am J Neuroradiol 2011; 32:1262-8. [PMID: 21527573 DOI: 10.3174/ajnr.a2475] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Stent-assisted endovascular treatment and flow diversion techniques are increasingly used for the management of wide-neck intracranial aneurysms. We report our initial clinical experience using a new flow diversion technique for the endovascular management of bifurcation aneurysms. MATERIALS AND METHODS Eight bifurcation aneurysms were treated by placing 2 stents in Y-configuration with no accompanying endosaccular packing. This treatment technique aimed at flow diversion was selected in these cases because 1) the aneurysm was giant and causing mass effect, 2) the emanating branches were incorporated within the sac, or 3) the aneurysm was too small. Aneurysms were located at middle cerebral (5 aneurysms) and basilar artery bifurcations (3 aneurysms). Five aneurysms were small, 1 was large, and 2 were partially thrombosed giant. Closed-cell stents were used in all Y-stent placement procedures. RESULTS In all aneurysms, both stents could be placed at the intended locations without any procedural complication. Follow-up angiograms obtained at 3 months to 2 years demonstrated that all stents were patent except for one with asymptomatic P1 occlusion. Complete occlusion with remodelled bifurcation was observed in all middle cerebral artery bifurcation aneurysms and the large basilar tip aneurysm. Residual filling despite reduction in size was observed in both of the partially thrombosed giant aneurysms at 2-year and 3-month follow-up angiograms, respectively. CONCLUSIONS Flow diversion with double stent placement in Y-configuration provided successful and stable aneurysm occlusion. The technical and clinical results achieved are highly encouraging that this technique may contribute to the endovascular treatment of these complex bifurcation aneurysms.
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Affiliation(s)
- H S Cekirge
- Department of Radiology, Hacettepe University Hospitals, Ankara, Turkey
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Mechanical design of an intracranial stent for treating cerebral aneurysms. Med Eng Phys 2010; 32:1015-24. [DOI: 10.1016/j.medengphy.2010.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 06/15/2010] [Accepted: 07/08/2010] [Indexed: 11/16/2022]
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Yoon WK, Kim YW, Kim SR, Park IS, Kim SD, Jo KW, Baik MW. Angiographic and clinical outcomes of stent-alone treatment for spontaneous vertebrobasilar dissecting aneurysm. Acta Neurochir (Wien) 2010; 152:1477-86; discussion 1486. [PMID: 20508955 DOI: 10.1007/s00701-010-0693-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 05/10/2010] [Indexed: 12/15/2022]
Abstract
PURPOSE Spontaneous vertebrobasilar dissecting aneurysm (VBD) is a very challenging disease with an unpredictable clinical course and controversies on treatment strategy. The present study reports radiological and clinical outcomes of stent-alone treatment (SAT) for VBD. METHODS Twenty-four VBDs treated with SAT are included in the present study. Clinical and angiographic data were reviewed retrospectively. RESULTS A total of 24 lesions in 22 patients with a mean follow-up period of 16.21 months were included. Of the 24 individual lesions, 23 were intracranial vertebral artery lesions and 1 lesion was located in the basilar artery. There were six cases of ruptured dissections with the other cases having various symptoms. The immediate post-SAT angiographic outcomes included 5 lesions with good remodeling over 90% recovery and 19 poorly remodeled lesions. The latest angiographic outcomes included 17 cases of good remodeling (remodeling rate over 90%), 6 cases of poor remodeling (remodeling rate below 70%), and 1 case with morphological aggravation. The overlapping stent technique was used in seven cases and it was significantly associated with good angiographic results. None of the rupture cases underwent re-rupture post SAT. There was one case of a symptomatic complication of a femoral arteriovenous fistula. CONCLUSIONS The SAT could be a feasible alternative for the treatment of VBD. The overlapping technique was significantly associated with good angiographic outcome. We expect that technological development of the intracranial stent will allow better procedural outcomes of SAT.
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Affiliation(s)
- Won Ki Yoon
- Department of Neurosurgery, Holy Family Hospital, The Catholic University of Korea, Sosa-dong, Wonmi-gu, Bucheon, Gyeonggi-do 429-717, Republic of Korea
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Bendok BR, Rahme RJ. Intracranial Stents for Aneurysms: Mere Scaffold or Hemodynamic Therapy? World Neurosurg 2010; 74:247-9. [DOI: 10.1016/j.wneu.2010.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Indexed: 11/15/2022]
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Saatci I, Geyik S, Yavuz K, Cekirge S. X-configured stent-assisted coiling in the endovascular treatment of complex anterior communicating artery aneurysms: a novel reconstructive technique. AJNR Am J Neuroradiol 2010; 32:E113-7. [PMID: 20595366 DOI: 10.3174/ajnr.a2111] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Incomplete initial occlusion rates and relatively less long-term durability remain as major problems of endovascular treatment of cerebral aneurysms. Stent-assisted coiling is a well-established current solution to overcome these problems. Double-stent treatment with a Y-configuration has been previously reported to improve the application of coiling to wide-neck bifurcation aneurysms. Herein, a novel technique of X-configured stent-assisted coiling for treatment of wide-neck and complex AcomA aneurysms is described.
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Affiliation(s)
- I Saatci
- Hacettepe University, Department of Radiology, Ankara, Turkey
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Kim YJ. Sole stenting technique for treatment of complex aneurysms. J Korean Neurosurg Soc 2009; 46:545-51. [PMID: 20062570 DOI: 10.3340/jkns.2009.46.6.545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 10/11/2009] [Accepted: 11/09/2009] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Complex aneurysms such as fusiform and very small aneurysms (< 3 mm) are challenging in neurovascular and endovascular surgery. Author reports follow-up results of 9 cases treated by sole stent technique with pertinent literature review. METHODS A retrospective study was made of 9 patients who were treated by sole stenting technique for cerebral aneurysm between January 2003 and January 2009. Two of them had fusiform aneurysm, 5 had very small aneurysm, and 2 had small saccular aneurysm. Five patients had ruptured aneurysms and four had unruptured aneurysms. Seven aneurysms were located in the internal carotid artery (ICA), 1 in the middle cerebral artery (MCA) and 1 in the basilar artery. Follow-up cerebral angiography was performed at post-procedure 3 months, 6 months, and 12 months. Mean follow-up period is 30 months (ranged from 3 days to 30 months). RESULTS Aneurysm size was decreased in 6 of 9 cases on follow-up images and was not changed in 3 cases. Although total occlusion was not seen, patients had stable neurological condition and angiographic result. The procedural complication occurred in 2 cases. One was coil migration and the other was suboptimal deployment of stent, and both were asymptomatic. Re-bleeding and thromboembolic complication had not been occurred. CONCLUSION Sole stenting technique is relatively effective and safe as an alternative treatment for fusiform and very small aneurysms.
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Affiliation(s)
- Young-Joon Kim
- Department of Neurosurgery, Dankook University College of Medicine, Cheonan, Korea
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Naggara O, Darsaut TE, Salazkin I, Soulez G, Guilbert F, Roy D, Weill A, Gevry G, Raymond J. A new canine carotid artery bifurcation aneurysm model for the evaluation of neurovascular devices. AJNR Am J Neuroradiol 2009; 31:967-71. [PMID: 20019111 DOI: 10.3174/ajnr.a1929] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Stents are increasingly used for coiling of difficult aneurysms, to reduce the risk of recurrences, or to modify blood flow. Currently available bifurcation aneurysm models are ill-suited to assess stent performance before clinical use. We designed a new wide-neck canine T-type bifurcation aneurysm model. Its potential value as a training tool as well as in the evaluation of new techniques or embolic agents was assessed. Our first task was to verify that recurrences occurred after satisfactory coiling. A second aim of this preliminary work was to assess if the new model could recreate the technical challenges involved in bifurcation aneurysms. MATERIALS AND METHODS We introduce a new canine wide-neck bifurcation aneurysm model, created by using a vein pouch at the apex of an end-to-side anastomosis of the carotid arteries, with flow reversal in the proximal RCA by ligation of the innominate artery. Three aneurysms were treated with coil embolization, 10 were treated with stents (7 self-expandable, 3 balloon-expandable), and 3 were left untreated. Aneurysms were followed by duplex ultrasonography and angiography, and studied with macroscopic photography after euthanasia 11.8 +/- 3.9 months after surgery. RESULTS All aneurysms remained patent at 9.0 +/- 3.6 months' follow-up. Coiling led to recurrences by 3 months in all 3 cases. Stent placement was technically difficult in all cases and did not lead to aneurysm thrombosis or neointimal closure of the aneurysm neck at 3 months. CONCLUSIONS This model may be suitable for studying the effects of endovascular treatment on aneurysm and branch occlusion rates, for preclinical testing of stents and other intravascular devices, and for training students of endovascular technique.
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Affiliation(s)
- O Naggara
- Interventional Neuroradiology Research Unit, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital, Montreal, Canada
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Augsburger L, Farhat M, Reymond P, Fonck E, Kulcsar Z, Stergiopulos N, Rüfenacht DA. Effect of Flow Diverter Porosity on Intraaneurysmal Blood Flow. Clin Neuroradiol 2009; 19:204-14. [PMID: 19705075 DOI: 10.1007/s00062-009-9005-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Accepted: 06/17/2009] [Indexed: 11/30/2022]
Affiliation(s)
- Luca Augsburger
- Laboratory of Hemodynamics and Cardiovascular Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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Augsburger L, Reymond P, Fonck E, Kulcsar Z, Farhat M, Ohta M, Stergiopulos N, Rüfenacht DA. Methodologies to assess blood flow in cerebral aneurysms: current state of research and perspectives. J Neuroradiol 2009; 36:270-7. [PMID: 19487029 DOI: 10.1016/j.neurad.2009.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 03/15/2009] [Accepted: 03/16/2009] [Indexed: 11/28/2022]
Abstract
With intracranial aneurysms disease bringing a weakened arterial wall segment to initiate, grow and potentially rupture an aneurysm, current understanding of vessel wall biology perceives the disease to follow the path of a dynamic evolution and increasingly recognizes blood flow as being one of the main stakeholders driving the process. Although currently mostly morphological information is used to decide on whether or not to treat a yet unruptured aneurysm, among other factors, knowledge of blood flow parameters may provide an advanced understanding of the mechanisms leading to further aneurismal growth and potential rupture. Flow patterns, velocities, pressure and their derived quantifications, such as shear and vorticity, are today accessible by direct measurements or can be calculated through computation. This paper reviews and puts into perspective current experimental methodologies and numerical approaches available for such purposes. In our view, the combination of current medical imaging standards, numerical simulation methods and endovascular treatment methods allow for thinking that flow conditions govern more than any other factor fate and treatment in cerebral aneurysms. Approaching aneurysms from this perspective improves understanding, and while requiring a personalized aneurysm management by flow assessment and flow correction, if indicated.
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Affiliation(s)
- L Augsburger
- Laboratory of Hemodynamics and Cardiovascular Technology, Ecole polytechnique fédérale de Lausanne, Ecublens, STI IB12 LHTC 1, A1 1241, Station 15, 1015 Lausanne, Vaud, Switzerland.
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Ionita CN, Paciorek AM, Dohatcu A, Hoffmann KR, Bednarek DR, Kolega J, Levy EI, Hopkins LN, Rudin S, Mocco JD. The asymmetric vascular stent: efficacy in a rabbit aneurysm model. Stroke 2009; 40:959-65. [PMID: 19131663 DOI: 10.1161/strokeaha.108.524124] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Development of hemodynamic modifying devices to treat intracranial aneurysms is an active area of research. The asymmetrical vascular stent (AVS), a stent containing a low-porosity patch, is such device. We evaluate AVS efficacy in an in vivo intracranial aneurysm model. METHODS We created 24 elastase rabbit model aneurysms: 13 treated with the AVS, 5 treated with standard coronary stents, and 6 untreated controls. Four weeks after treatment, aneurysms underwent follow-up angiography, cone-beam micro-CT, histological evaluation, and selective electron microscopy scanning. RESULTS Four rabbits died early in the study: 3 during AVS treatment and 1 control (secondary to intraprocedural vessel injury and an unrelated tumor, respectively). AVS-treated aneurysms exhibited very weak or no aneurysm flow immediately after treatment and no flow in all aneurysms at follow-up. Standard stent-treated aneurysms showed flow both after treatment (5/5) and at follow-up (3/5). All control aneurysms remained patent during the study. Micro-CT scans showed: 9 of 9 scanned AVS aneurysms were occluded, 6 of 9 AVS were ideally placed, and 3 of 9 low-porosity region partially covered the aneurysm neck; standard stent-treated aneurysms were 1 of 5 occluded, 2 of 5 patent, and 2 of 5 partially patent. Histology results demonstrated: for AVS-treated aneurysms, advanced thrombus organization in the (9/9); for standard stent-treated aneurysms, (1/4) no thrombus, (2/4) partially thrombosed, and (1/4) fully thrombosed; for control aneurysms (4/4), no thrombus. CONCLUSIONS The use of AVS shows promise as a viable new therapeutic in intracranial aneurysm treatment. These data encourage further investigation and provide substantial support to the AVS concept.
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Affiliation(s)
- Ciprian N Ionita
- Department of Neurosurgery, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA.
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Medical application oriented blood flow simulation. Clin Biomech (Bristol, Avon) 2008; 23 Suppl 1:S130-6. [PMID: 18023946 DOI: 10.1016/j.clinbiomech.2007.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 09/15/2007] [Accepted: 09/24/2007] [Indexed: 02/07/2023]
Abstract
In order to show the application of computational fluid dynamics in biomedical engineering, some numerical simulations of blood flow in arteries, such as hemodynamics of bypass graft for stenosed arteries, hemodynamics of stented aneurysm at the aortic arch, hemodynamics of bypass treatment for DeBakey III aortic dissection, and influence of blood flow on the thermal characteristics of microwave ablation, which were performed by the authors, were reviewed. These simulations can be a powerful tool for the computer assisted surgery in medical application.
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Yavuz K, Geyik S, Saatci I, Cekirge HS. WingSpan Stent System in the endovascular treatment of intracranial aneurysms: clinical experience with midterm follow-up results. J Neurosurg 2008; 109:445-53. [PMID: 18759575 DOI: 10.3171/jns/2008/109/9/0445] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The WingSpan stent is a new self-expandable neurovascular stent designed for endovascular treatment of intracranial atheromatous lesions. The authors report their experience with the use of this stent for the endovascular treatment of intracranial aneurysms. METHODS Thirty-seven patients with 40 wide-necked intracranial aneurysms were treated using the WingSpan stent. Twenty-two aneurysms (55%) were small and 18 (45%) were large or giant. In all but 4 aneurysms, embolization was completed by packing the aneurysm sac with platinum coils. In 4 dissecting aneurysms that were fusiform or too small and wide necked to be catheterized, the stent was used alone. In these cases, the stent bridged the aneurysm neck to allow for flow redirection and the potential stent-induced endothelization effect. RESULTS Follow-up angiograms obtained in 3 of 4 aneurysms, treated with only stent placement, demonstrated aneurysmal thrombosis and parent artery remodeling in 2 patients and moderate decrease in size in 1. Follow-up angiography obtained at 6 months to 1 year in 31 aneurysms after stent-supported coil embolization demonstrated complete occlusion in 23 aneurysms (74.2%) with a progressive thrombosis rate of 66.7% (10 of 15 aneurysms), and a recanalization rate of 16.1%. CONCLUSIONS In treating wide-necked intracranial aneurysms, the WingSpan Stent System is very flexible, secure, and effective. Its delivery system is very easy and exact in that it exerts higher outward radial force, thus providing an excellent conformability and a strong scaffold to hold the coils in place. It may offer an effective treatment when used alone in some fusiform or very wide-necked, small dissecting aneurysms in which other surgical or endovascular treatment strategies are not deemed feasible.
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Affiliation(s)
- Kivilcim Yavuz
- Department of Radiology, Hacettepe University Hospitals, Ankara, Turkey
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Stents for intracranial wide-necked aneurysms: more than mechanical protection. Neuroradiology 2008; 50:991-8. [PMID: 18807024 DOI: 10.1007/s00234-008-0460-0] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 09/02/2008] [Indexed: 10/21/2022]
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Ohta M, Hirabayashi M, Wetzel S, Lylyk P, Wata H, Tsutsumi S, Rüfenacht DA. Impact of stent design on intra-aneurysmal flow. A computer simulation study. Interv Neuroradiol 2008; 10 Suppl 2:85-94. [PMID: 20587255 DOI: 10.1177/15910199040100s216] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 10/01/2004] [Indexed: 11/16/2022] Open
Abstract
SUMMARY In addition to providing a skeleton for vessel reconstruction, stent implantation as used for cerebral aneurysm treatment can induce flow redirection, thus reducing vortical flow velocities within the aneurysm cavity. Further, stent characteristics such as strut size, porosity and cell shape influence the changes in intra-aneurysmal flow by analog simulations. The purpose of this computer simulation study was to visualize the flow pattern over the entire neck area of a side wall aneurysm while changing the stent parameters. A 3-D computer model aneurysm was constructed to have a parent artery of 5 mm diameter and an aneurysm of 10 mm diameter. The distance between the midline of main artery and center point of the aneurysm was 6.8 mm, providing a neck length of 5 mm, a width of 3.6 mm, and a neck area of 14 mm 2. The simulations were carried out with a Finite Element Method based flow simulation package. The incompressible Navier-Stokes equation was solved for a steady flow with a mean speed of 290 mm/s, steady viscosity of 3.83 cp, and density of 1.0 g/cm3. Two parallel stent struts (dimensions: 100 mum m 100 mum m 2.0 mm) were introduced into the plane of the aneurysm neck. The fraction of the aneurysm neck cross-section occupied by the stent was 2.83% in all cases. The velocity distribution through the neck of the aneurysm was calculated for three different choices of separation between the struts for each of two orientations of the struts (parallel and perpendicular) relative to the vessel axis. The flow pattern in the aneurysm was composed of an inflow zone at the distal neck and of an outflow zone at the proximal neck. The placement of stent struts at the aneurysm neck resulted in a decrease in the mean speed in the aneurysm. The degree of reduction and the distribution of flow through the neck did depend on the orientation of the stent struts. The struts, when placed parallel or perpendicular to the parent vessel axis affected the mean speed through the aneurysm neck differently.
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Affiliation(s)
- M Ohta
- Section of Neuroradiology, Department of Radiology, Geneva University Hospital, Geneva; Switzerland
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Ionita CN, Paciorek AM, Hoffmann KR, Bednarek DR, Yamamoto J, Kolega J, Levy EI, Hopkins LN, Rudin S, Mocco J. Asymmetric vascular stent: feasibility study of a new low-porosity patch-containing stent. Stroke 2008; 39:2105-13. [PMID: 18436886 DOI: 10.1161/strokeaha.107.503862] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Intracranial aneurysm (IA) treatment through hemodynamic modification with novel stent designs is a burgeoning area of research. We present a feasibility study for a new low-porosity patch-containing stent designed to treat intracranial aneurysms. The device is deployed so the patch covers the aneurysm neck ensuring strong flow diversion away from the aneurysm while keeping a low probability of occlusion of perforating vessels. METHODS We created 17 side-wall aneurysms in 6 dogs, 2 per carotid artery if animal size permitted. Twelve proximal aneurysms were treated with AVSs: 5 distal aneurysms were untreated, serving as controls against self-thrombosis; 7 treated aneurysms were fully-covered; and 5 were partially-covered. After 4 weeks, a final angiogram was performed and aneurysms were explanted. Angiograms acquired pre- and posttreatment and at 4-week follow-up were analyzed quantitatively using normalized time-density curves (NTDC). Cone-beam micro-CT and histological specimen analysis were then performed. RESULTS Posttreatment, NTDC average peaks dropped to 45% of initial values for the partially-covered aneurysms and 78% for the fully-covered aneurysms. Cone-beam micro-CT imaging performed at 4 weeks posttreatment showed partial thrombosis in 4 of 5 partially-covered aneurysms and complete thrombosis in all fully-covered aneurysms. Histology revealed neointimal coverage of all asymmetrical patch regions and thrombus formation in both fully- and partially-covered aneurysms. Four-week follow-up was not done for 1 animal (2 controls, 2 treated) that expired because of groin hemorrhage and for another animal (1 aneurysm) with an occluded carotid. CONCLUSIONS We demonstrate aneurysmal blood flow diversion using a new low-porosity patch-containing asymmetrical vascular stent in a canine side-wall aneurysm model. Overall results are encouraging and support continued AVS development.
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Affiliation(s)
- Ciprian N Ionita
- Department of Neurosurgery, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY 14209, USA
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Chen Z, Feng H, Tang W, Liu Z, Miao H, Zhu G. Endovascular treatment of very small intracranial aneurysms. ACTA ACUST UNITED AC 2008; 70:30-5; discussion 35. [PMID: 18262637 DOI: 10.1016/j.surneu.2007.05.059] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 05/21/2008] [Indexed: 11/27/2022]
Abstract
BACKGROUND The treatment of very small cerebral aneurysms with maximal diameter less than 3 mm remains a challenge for endovascular and surgical treatment. Endovascular treatment of these lesions may be difficult and associated with high risk of complications because of their small size. Our purpose was to assess the feasibility and results of endovascular treatment of these lesions. METHODS We conducted a retrospective review of our experience and results of endovascular treatments for a series of 11 consecutive patients with 11 very small aneurysms. Of 11 aneurysms, 10 were acutely ruptured, and 1 was unruptured with a previous subarachnoid hemorrhage from another aneurysm. Aneurysms were located at the internal carotid artery (n = 4), the anterior communicating artery (n = 6), and the vertebral artery (n = 1). Seven patients were treated with coil embolization, and remodeling technique was used in 1 case. Three cases underwent intravascular stent implantation. Coil packing was done after in 2 of 3 aneurysms, and stent implantation alone was used in the remaining aneurysm. RESULTS Coil embolization and stent deployment were carried out without difficulty in all cases. Coil packing was not available after stent implantation in 1 case for unsuccessful navigation of microcatheter into the aneurysm sac. Immediate angiography demonstrated complete occlusion in 10 cases and nearly complete occlusion in 1 case with stent implantation alone. No stent thrombosis and aneurysmal rupture was encountered during treatment. With the exception of 1 patient (Hunt and Hess grade 4) who died of pneumonia 4 weeks after treatment, no clinical evidence of neurologic deterioration and hemorrhagic complication was seen during the follow-up period in the remaining 10 patients. Follow-up angiography for 3 to 12 months (mean, 5.3 months) was available in 6 (60%) of 10 surviving patients, and no aneurysm recanalization was found. CONCLUSIONS Endovascular treatment may be a feasible and effective therapeutic alternative for very small aneurysms. The long-term efficacy and durability of endovascular treatment for these lesions remains to be determined in a large series.
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Affiliation(s)
- Zhi Chen
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
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Effects of stent porosity on hemodynamics in a sidewall aneurysm model. J Biomech 2008; 41:1174-83. [PMID: 18377914 DOI: 10.1016/j.jbiomech.2008.01.025] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 12/11/2007] [Accepted: 01/30/2008] [Indexed: 11/21/2022]
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Lee DH, Arat A, Morsi H, Diaz O, Jou LD, Mawad ME. Intimal Thickening after Placement of a Neuroform Stent. Its Incidence and Relation to Angiographic Follow-up Results of Aneurysm Embolization. Interv Neuroradiol 2007; 13:239-46. [PMID: 20566115 DOI: 10.1177/159101990701300303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2007] [Accepted: 08/14/2007] [Indexed: 11/15/2022] Open
Abstract
SUMMARY Little attention has been given to the intimal thickening of the parent artery associated with the use of Neuroform stent. The purposes of this study were are to analyze quantifyanalyze the incidence of the parent artery intimal thickening the incidence and pattern of luminal changes, to to see somedetermine possible predictors of the phenomenonof the intimal thickening, to to evaluate the its effectthe phenomenonrestenosis on the aneurysm treatment results. We reviewed the initial and six-month followup angiographic images in 32 intracranial aneurysm patients treated with Neuroform stent and coilsin wide-necked aneurysm treatment. The initial embolization results were evaluated by the Raymond and Roy classification. The angiographic changes from immediate post-embolization to the six-month follow-up were classified as 'improved', 'unchanged' and 'worse'. The occurrencerates of parent artery intimal thickening was observed. Any perceivable change in the stented segment of the parent artery was considered as 'intimal thickening' and any change of >/=50% as 'significant thickening'. Fisher exact tests and logistic regression analysis were applied to determine the relation between the occurrence of the intimal thickening and several variables. The incidence of the intimal thickening was 18.8% (6/32) and of significant thickening, 3.1% (1/32). The change in angiographic occlusion of the aneurysm was 'improved' in 40.6% (13/32), 'unchanged' in 37.5% (12/32), and 'worse' in 21.9% (7/32). Among the variables, patient's age (>/=55) and follow-up angiographic results ('improved') correlated with the occurrence of the intimal thickening. Of notable finding was all six cases with intimal thickening of the parent artery were associated with 'improved' in their followup angiographic result. Neuroform-associated intimal thickening usually occurs in younger patients and is frequently associated with improved angiographic result of the aneurysm embolization on follow-up.
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Affiliation(s)
- D H Lee
- Department of Radiology, St. Luke's Episcopal Hospital, Baylor College of Medicine, USA - Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, USA -
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