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Kim S, Yang H, Oh JH, Kim YB. Quantitative analysis of hemodynamic changes induced by the discrepancy between the sizes of the flow diverter and parent artery. Sci Rep 2024; 14:10653. [PMID: 38724557 PMCID: PMC11081945 DOI: 10.1038/s41598-024-61312-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/03/2024] [Indexed: 05/12/2024] Open
Abstract
The efficacy of flow diverters is influenced by the strut configuration changes resulting from size discrepancies between the stent and the parent artery. This study aimed to quantitatively analyze the impact of size discrepancies between flow diverters and parent arteries on the flow diversion effects, using computational fluid dynamics. Four silicone models with varying parent artery sizes were developed. Real flow diverters were deployed in these models to assess stent configurations at the aneurysm neck. Virtual stents were generated based on these configurations for computational fluid dynamics analysis. The changes in the reduction rate of the hemodynamic parameters were quantified to evaluate the flow diversion effect. Implanting 4.0 mm flow diverters in aneurysm models with parent artery diameters of 3.0-4.5 mm, in 0.5 mm increments, revealed that a shift from oversized to undersized flow diverters led to an increase in the reduction rates of hemodynamic parameter, accompanied by enhanced metal coverage rate and pore density. However, the flow diversion effect observed transitioning from oversizing to matching was less pronounced when moving from matching to undersizing. This emphasizes the importance of proper sizing of flow diverters, considering the benefits of undersizing and not to exceed the threshold of advantages.
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Affiliation(s)
- Sunghan Kim
- Department of Neurosurgery, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Hyeondong Yang
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do, 15588, Republic of Korea
| | - Je Hoon Oh
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do, 15588, Republic of Korea.
| | - Yong Bae Kim
- Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea.
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Kokkinidou D, Kaliviotis E, Shammas C, Anayiotos A, Kapnisis K. An in vivo investigation on the effects of stent implantation on hematological and hemorheological parameters. Clin Hemorheol Microcirc 2024; 87:39-53. [PMID: 38143339 DOI: 10.3233/ch-231921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2023]
Abstract
BACKGROUND Even though cardiovascular stenting is widely used for the treatment of coronary artery disease, information on how it can affect the hematological and hemorheological profile is scarce in the literature. Most of the work on this issue is based on theoretical or computational fluid dynamics models, lacking in-depth in vitro and in vivo experimental verification. OBJECTIVE This work investigates, in an in vivo setting, the effects of stenting and the implantation time-course on hematological and hemorheological parameters that could potentially compromise the device's functionality and longevity. METHODS Custom-made self-expanding nitinol stents were implanted in the common carotid artery of male CD1 mice. Whole blood samples were collected from control (non-stented) and stented animals at 5 and 10 weeks post-implantation. Hematological measurements and blood viscosity, red blood cell aggregation, and deformability were performed using standard techniques. RESULTS Implant-induced changes were observed in some of the hematological and hemorheological indices. Blood viscosity seems to have been negatively affected by an increased hematocrit and reduced RBC deformability, at 10 weeks post-implantation, despite a slight decrease in RBC aggregation. CONCLUSIONS Although the alterations observed may be the result of the peri-implant inflammatory response, the physiological consequences due to hemorheological changes need to be further investigated.
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Affiliation(s)
- D Kokkinidou
- Department of Mechanical Engineering and Material Science and Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - E Kaliviotis
- Department of Mechanical Engineering and Material Science and Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - C Shammas
- BIOANALYSIS Clinical Laboratory, Limassol, Cyprus
| | - A Anayiotos
- Department of Mechanical Engineering and Material Science and Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - K Kapnisis
- Department of Mechanical Engineering and Material Science and Engineering, Cyprus University of Technology, Limassol, Cyprus
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Li X, Li Z, Jiang W, Wei J, Xu K, Bai T. Effect of lower extremity amputation on cardiovascular hemodynamic environment: An in vitro study. J Biomech 2022; 145:111368. [PMID: 36347116 DOI: 10.1016/j.jbiomech.2022.111368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 10/13/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022]
Abstract
Lower extremity amputation (LEA) was associated with a greater risk of cardiovascular disease, but its hemodynamic mechanisms have not been fully studied. Therefore, to clarify the interrelationship between them, and figure out the potential pathogenesis, the exploration of the hemodynamic environment change of patients after LEA was premeditatedly executed. A near-physiological mock circulatory system (MCS) was employed in the present work to replicate the cardiovascular circulation after LEA in a short time and the unsteady-state numerical simulation was utilized as an auxiliary method to observe the changes of the hemodynamic environment inside the blood vessel. Higher severity of LEA leads to higher peripheral vascular impedance, higher blood pressure, and more obvious redistribution of blood perfusion volume. In addition, higher severity of LEA leads to lower wall shear stress (WSS), higher oscillatory shear index (OSI), and higher relative residence time (RRT) appeared in the infrarenal abdominal aorta and the iliac artery, while these changes are closely related to the higher probability of cardiovascular diseases. Results showed that different degrees of LEA (varying heights, unilateral/bilateral) have diverse effects on the patient's hemodynamic environment. This study explained the potential pathogenesis of cardiovascular diseases after LEA from a hemodynamic perspective and provided a certain reference value for the improvement of the cardiovascular hemodynamic environment and the prevention of cardiovascular diseases in lower extremity amputees.
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Affiliation(s)
- Xiao Li
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China
| | - Zhongyou Li
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China
| | - Wentao Jiang
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China.
| | - Junru Wei
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China
| | - Kairen Xu
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China
| | - Taoping Bai
- Department of Mechanical Science and Engineering, Sichuan University, China; Biomechanical Engineering Laboratory of Sichuan Province, Chengdu, China
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Kim S, Yang H, Hong I, Oh JH, Kim YB. Computational Study of Hemodynamic Changes Induced by Overlapping and Compacting of Stents and Flow Diverter in Cerebral Aneurysms. Front Neurol 2021; 12:705841. [PMID: 34408723 PMCID: PMC8365227 DOI: 10.3389/fneur.2021.705841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/14/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: The flow diversion effect of an intracranial stent is closely related to its metal coverage rate (MCR). In this study, the flow diversion effects of Enterprise and low-profile visualized intraluminal support (LVIS) stents are compared with those of a Pipeline flow diverter, focusing on the MCR change. Moreover, the changes in the flow diversion effect caused by the additional manipulations of overlapping and compaction are verified using computational fluid dynamics (CFD) analysis. Methods: CFD analysis was performed using virtually generated stents mounted in an idealized aneurysm model. First, the flow diversion effects of single Enterprise, LVIS, and Pipeline devices were analyzed. The Enterprise and LVIS were sequentially overlapped and compared with a Pipeline, to evaluate the effect of stent overlapping. The effect of compacting a stent was evaluated by comparing the flow diversion effects of a single and two compacted LVIS with those of two overlapped, uncompacted LVIS and uncompacted and compacted Pipeline. Quantitative analysis was performed to evaluate the hemodynamic parameters of energy loss, average velocity, and inflow rate. Results: Statistically significant correlations were observed between the reduction rates of the hemodynamic parameters and MCR. The single LVIS without compaction induced a reduction in all the hemodynamic parameters comparable to those of the three overlapped Enterprise. Moreover, the two overlapped, uncompacted LVIS showed a flow diversion effect as large as that induced by the single uncompacted Pipeline. Compacted stents induced a better flow diversion effect than uncompacted stents. The single compacted LVIS induced a flow diversion effect similar to that induced by the two uncompacted LVIS or single uncompacted Pipeline. Conclusions: The MCR of a stent correlates with its flow diversion effect. Overlapping and compaction can increase the MCR of an intracranial stent and achieve a flow diversion effect as large as that observed with a flow diverter.
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Affiliation(s)
- Sunghan Kim
- Department of Neurosurgery, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.,Department of Neurosurgery, Severance Stroke Center, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
| | - Hyeondong Yang
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, South Korea
| | - Ineui Hong
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, South Korea
| | - Je Hoon Oh
- Department of Mechanical Engineering and BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, South Korea
| | - Yong Bae Kim
- Department of Neurosurgery, Severance Stroke Center, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
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Analysis of Morphological-Hemodynamic Risk Factors for Aneurysm Rupture Including a Newly Introduced Total Volume Ratio. J Pers Med 2021; 11:jpm11080744. [PMID: 34442388 PMCID: PMC8399007 DOI: 10.3390/jpm11080744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/27/2022] Open
Abstract
The purpose of this study was to evaluate morphological and hemodynamic factors, including the newly developed total volume ratio (TVR), in evaluating rupture risk of cerebral aneurysms using ≥7 mm sized aneurysms. Twenty-three aneurysms (11 unruptured and 12 ruptured) ≥ 7 mm were analyzed from 3-dimensional rotational cerebral angiography and computational fluid dynamics (CFD). Ten morphological and eleven hemodynamic factors of the aneurysms were qualitatively and quantitatively compared. Correlation analysis between morphological and hemodynamic factors was performed, and the relationship among the hemodynamic factors was analyzed. Morphological factors (ostium diameter, ostium area, aspect ratio, and bottleneck ratio) and hemodynamic factors (TVR, minimal wall shear stress of aneurysms, time-averaged wall shear stress of aneurysms, oscillatory shear index, relative residence time, low wall shear stress area, and ratio of low wall stress area) were statistically different between ruptured and unruptured aneurysms (p < 0.05). By simple regression analysis, the morphological factor aspect ratio and the hemodynamic factor TVR were significantly correlated (r2 = 0.602, p = 0.001). Ruptured aneurysms had complex and unstable flow. In ≥7 mm ruptured aneurysms, high aspect ratio, bottleneck ratio, complex flow, unstable flow, low TVR, wall shear stress at aneurysm, high oscillatory shear index, relative resistance time, low wall shear stress area, and ratio of low wall stress area were significant in determining the risk of aneurysm rupture.
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Dazeo N, Muñoz R, Narata AP, Fernandez H, Larrabide I. Intra-saccular device modeling for treatment planning of intracranial aneurysms: from morphology to hemodynamics. Int J Comput Assist Radiol Surg 2021; 16:1663-1673. [PMID: 34195929 DOI: 10.1007/s11548-021-02427-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/28/2021] [Indexed: 10/21/2022]
Abstract
MOTIVATION Intra-saccular devices (ID), developed for the treatment of bifurcation aneurysms, offer new alternatives for treating complex terminal and bifurcation aneurysms. In this work, a complete workflow going from medical images to post-treatment CFD analysis is described and used in the assessment of a concrete clinical problem. MATERIALS AND METHODS Two different intra-saccular device sizes were virtually implanted in 3D models of the patient vasculature using the ID-Fit method. After deployment, the local porosity at the closed end of the device in contact with the blood flow was computed. This porosity was then used to produce a CFD porous medium model of the device. Velocities and wall shear stress were assessed for each model. RESULTS Six patients treated with intra-saccular devices were included in this work. For each case, 2 different device sizes were virtually implanted and 3 CFD simulations were performed: after deployment simulation with each size and before deployment simulation (untreated). A visible reduction in velocities was observed after device implantation. Velocity and WSS reduction was statistically significant (K-S statistics, [Formula: see text]). CONCLUSIONS Placement of different device size can lead to a partial filling of the aneurysm, either at the dome or at the neck, depending on the particular positioning by the interventionist. The methodology used in this work can have a strong clinical impact, since it provides additional information in the process of device selection using preoperative data.
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Affiliation(s)
- Nicolás Dazeo
- Instituto Pladema - CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.
| | - Romina Muñoz
- Instituto Pladema - CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina
| | - Ana Paula Narata
- Neuroradiology Department, University Hospital of Southampton, Southampton, UK
| | | | - Ignacio Larrabide
- Instituto Pladema - CONICET, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.,Galgo Medical S.L., Barcelona, Spain
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7
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Computational methods applied to analyze the hemodynamic effects of flow-diverter devices in the treatment of cerebral aneurysms: Current status and future directions. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2019. [DOI: 10.1016/j.medntd.2019.100018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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8
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Evaluating the Effectiveness of 2 Different Flow Diverter Stents Based on the Stagnation Region Formation in an Aneurysm Sac Using Lagrangian Coherent Structure. World Neurosurg 2019; 127:e727-e737. [DOI: 10.1016/j.wneu.2019.03.255] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 03/23/2019] [Accepted: 03/25/2019] [Indexed: 12/16/2022]
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9
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Teramoto S, Oishi H, Arai H. Comparative Analysis of Long-Term Effect of Stent-Assisted Coiling in Unruptured Sidewall-Type and Terminal-Type Aneurysms. World Neurosurg 2019; 126:e753-e757. [DOI: 10.1016/j.wneu.2019.02.145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 02/14/2019] [Accepted: 02/15/2019] [Indexed: 11/30/2022]
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Shamloo A, Nejad MA, Saeedi M. Fluid–structure interaction simulation of a cerebral aneurysm: Effects of endovascular coiling treatment and aneurysm wall thickening. J Mech Behav Biomed Mater 2017; 74:72-83. [DOI: 10.1016/j.jmbbm.2017.05.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/09/2017] [Accepted: 05/12/2017] [Indexed: 12/01/2022]
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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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12
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Advanced flow MRI: emerging techniques and applications. Clin Radiol 2016; 71:779-95. [PMID: 26944696 DOI: 10.1016/j.crad.2016.01.011] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/10/2015] [Accepted: 01/10/2016] [Indexed: 12/12/2022]
Abstract
Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented.
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Nam HG, Yoo CM, Baek SM, Kim HK, Shin JH, Hwang MH, Jo GE, Kim KS, Cho JH, Lee SH, Kim HC, Lim CH, Choi H, Sun K. Enhancement of Mechanical Properties and Testing of Nitinol Stents in Cerebral Aneurysm Simulation Models. Artif Organs 2015; 39:E213-26. [DOI: 10.1111/aor.12564] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hyo Geun Nam
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Chang Min Yoo
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Seoung Min Baek
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Han Ki Kim
- Department of Mechanical Engineering; Dankook University; Yongin Korea
| | - Jae Hee Shin
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Min Ho Hwang
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Ga Eun Jo
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Kyong Soo Kim
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Jae Hwa Cho
- College of Medicine; Radiation Applied Life Science; Seoul National University; Seoul Korea
| | - Seung Hoon Lee
- Department of Otorhinolaryngology-Head and Neck Surgery; College of Medicine; Korea University; Seoul Korea
| | - Ho Chul Kim
- Department of Radiological Science; Eulji University; Seongnam Korea
| | - Chun Hak Lim
- Department of Anesthesiology and Pain Medicine; College of Medicine; Korea University; Seoul Korea
| | - Hyuk Choi
- Department of Medical Sciences; Graduate School of Medicine; Korea University; Seoul Korea
| | - Kyung Sun
- Thoracic and Cardiovascular Surgery; College of Medicine; Korea University; Seoul Korea
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Benz T, Kowarschik M, Endres J, Redel T, Demirci S, Navab N. A Fourier-based approach to the angiographic assessment of flow diverter efficacy in the treatment of cerebral aneurysms. IEEE TRANSACTIONS ON MEDICAL IMAGING 2014; 33:1788-1802. [PMID: 24801649 DOI: 10.1109/tmi.2014.2320602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Flow diversion is an emerging endovascular treatment option for cerebral aneurysms. Quantitative assessment of hemodynamic changes induced by flow diversion can aid clinical decision making in the treatment of cerebral aneurysms. In this article, besides summarizing past key research efforts, we propose a novel metric for the angiographic assessment of flow diverter deployments in the treatment of cerebral aneurysms. By analyzing the frequency spectra of signals derived from digital subtraction angiography (DSA) series, the metric aims to quantify the prevalence of frequency components that correspond to the patient-specific heart rate. Indicating the decoupling of aneurysms from healthy blood circulation, our proposed metric could advance clinical guidelines for treatment success prediction. The very promising results of a retrospective feasibility study on 26 DSA series warrant future efforts to study the validity of the proposed metric within a clinical setting.
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Rodriguez JN, Hwang W, Horn J, Landsman TL, Boyle A, Wierzbicki MA, Hasan SM, Follmer D, Bryant J, Small W, Maitland DJ. Design and biocompatibility of endovascular aneurysm filling devices. J Biomed Mater Res A 2014; 103:1577-94. [PMID: 25044644 DOI: 10.1002/jbm.a.35271] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/01/2014] [Accepted: 06/12/2014] [Indexed: 12/13/2022]
Abstract
The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.
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Affiliation(s)
- Jennifer N Rodriguez
- Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College Station, Texas, 77843
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16
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Tanemura H, Ishida F, Miura Y, Umeda Y, Fukazawa K, Suzuki H, Sakaida H, Matsushima S, Shimosaka S, Taki W. Changes in hemodynamics after placing intracranial stents. Neurol Med Chir (Tokyo) 2014; 53:171-8. [PMID: 23524501 DOI: 10.2176/nmc.53.171] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stent-assisted coil embolization has enabled the endovascular treatment of wide-necked cerebral aneurysms. Moreover, recent reports demonstrated that stent-assisted coil embolization was associated with a significant decrease in angiographic recurrences of coiled cerebral aneurysms. One of the possible explanations for this adjunctive effect of stent-assisted coil embolization is changes in the local hemodynamics caused by placing intracranial stents. This study investigated the hemodynamic effect of intracranial stents using computational fluid dynamics (CFD) analysis. The geometry of the intracranial stent, Enterprise(TM) VRD, was acquired by using micro computed tomography and virtually placed across the aneurysm orifice of a saccular aneurysm model (saccular model) and a blister-like aneurysm model (blister-like model) constructed from patient-specific three-dimensional (3D) rotational angiography data. Transient CFD analysis was performed with these models with and without stents. Stent placement induced no significant changes in the 3D streamline in the saccular model and slight changes in the blister-like model. Both saccular and blister-like models with stents had lower wall shear stress (WSS) and flow velocity, and higher oscillatory shear index, WSS gradient, and relative residence time than the equivalent models without stents, indicating the possibility that stent placement induced stagnant and disturbed blood flow. Cross-sectional vector velocity around the stent strut revealed complex blood flow patterns with variable direction and velocity. Although this study was a simulation under limited conditions, similar hemodynamic changes might be induced in the neck remnants treated with stent-assisted coil embolization.
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Affiliation(s)
- Hiroshi Tanemura
- Department of Neurosurgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
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Schnell S, Ansari SA, Vakil P, Wasielewski M, Carr ML, Hurley MC, Bendok BR, Batjer H, Carroll TJ, Carr J, Markl M. Three-dimensional hemodynamics in intracranial aneurysms: influence of size and morphology. J Magn Reson Imaging 2013; 39:120-31. [PMID: 24151067 DOI: 10.1002/jmri.24110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 02/12/2013] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To use four-dimensional (4D)-flow MRI for the comprehensive in vivo analysis of hemodynamics and its relationship to size and morphology of different intracranial aneurysms (IA). We hypothesize that different IA groups, defined by size and morphology, exhibit different velocity fields, wall shear stress, and vorticity. MATERIALS AND METHODS The 4D-flow MRI (spatial resolution = 0.99-1.8 × 0.78-1.46 × 1.2-1.4 mm(3) , temporal resolution = 44-48 ms) was performed in 19 IAs (18 patients, age = 55.4 ± 13.8 years) with saccular (n = 16) and fusiform (n = 3) morphology and different sizes ranging from small (n = 8; largest dimension = 6.2 ± 0.4 mm) to large and giant (n = 11; 25 ± 7 mm). Analysis included quantification of volumetric spatial-temporal velocity distribution, vorticity, and wall shear stress (WSS) along the aneurysm's 3D surface. RESULTS The 4D-flow MRI revealed distinct hemodynamic patterns for large/giant saccular aneurysms (Group 1), small saccular aneurysms (Group 2), and large/giant fusiform aneurysms (Group 3). Saccular IA (Groups 1, 2) demonstrated significantly higher peak velocities (P < 0.002) and WSS (P < 0.001) compared with fusiform aneurysms. Although intra-aneurysmal 3D velocity distributions were similar for Group 1 and 2, vorticity and WSS was significantly (P < 0.001) different (increased in Group 1 by 54%) indicating a relationship between IA size and hemodynamics. Group 3 showed reduced velocities (P < 0.001) and WSS (P < 0.001). CONCLUSION The 4D-flow MRI demonstrated the influence of lesion size and morphology on aneurysm hemodynamics suggesting the potential of 4D-flow MRI to assist in the classification of individual aneurysms.
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Affiliation(s)
- Susanne Schnell
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
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Galal A, Bahrassa F, Dalfino JC, Boulos AS. Stent-assisted treatment of unruptured and ruptured intracranial aneurysms: clinical and angiographic outcome. Br J Neurosurg 2013; 27:607-16. [DOI: 10.3109/02688697.2012.757292] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Pieper CC, Meyer C, Verrel F, Schild HH, Wilhelm KE. Using the Multilayer Stent as a Supplement to EVAR in Combined Abdominal Aortic Aneurysm and Iliac Artery Aneurysm With Inadequate Distal Landing Zone—A Case Report. Vasc Endovascular Surg 2012; 46:565-9. [DOI: 10.1177/1538574412456306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Combined abdominal aortic aneurysm (AAA) and iliac artery aneurysm (IAA) is a common condition. The recently approved Cardiatis Multilayer stent (Cardiatis, Isnes, Belgium) is an innovative stent system for peripheral aneurysm management that has been applied in several clinical cases. After deployment, the unique stent design reduces mean velocity and vorticity within the aneurysm sac, causing thrombus formation and thus exclusion of the aneurysm while the vessels branching from the aneurysm remain patent. We describe a case of combined AAA and IAA with successful endovascular aneurysm repair of the AAA and treatment of the internal iliac artery with the Cardiatis Multilayer stent at 12 months of follow-up.
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Affiliation(s)
| | - Carsten Meyer
- Department of Radiology, University of Bonn, Bonn, Germany
| | - Frauke Verrel
- Department of Surgery, University of Bonn, Bonn, Germany
| | - Hans H. Schild
- Department of Radiology, University of Bonn, Bonn, Germany
| | - Kai E. Wilhelm
- Department of Radiology, University of Bonn, Bonn, Germany
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Bell RS, Bank WO, Armonda RA, Vo AH, Kerber CW. Can a self-expanding aneurysm stent be clipped? Emergency proximal control options for the vascular neurosurgeon. Neurosurgery 2012; 68:1056-62. [PMID: 21242822 DOI: 10.1227/neu.0b013e31820d5396] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND If a self-expanding stent has been placed during endovascular treatment of an aneurysm and subsequently an open aneurysm surgery becomes necessary in the same or an adjacent area, is it possible and safe to obtain proximal control by placing a temporary clip on the artery at a point where it contains the stent? OBJECTIVE To evaluate the effect of temporary clip application to 3 separate stent systems in an in vitro flow model with the stated hypothesis that clip application to these stents will result in permanent stent deformation. METHODS This is an in vitro flow model study using an accepted synthetic blood vessel substitute. The Neuroform(3) (Boston Scientific), Enterprise (Cordis/Codman), and Pipeline (ev3) stents were deployed within the flow model; temporary clips were applied; and angiographic measurements subsequently made. RESULTS Two 4 × 30-mm Neuroform(3) stents, two 4.5 × 28-mm Enterprise stents, and two 3.75 × 20-mm Pipeline stents were successfully deployed and clipped repeatedly (4 iterations). Two- and 3-dimensional angiograms were obtained. After repeated clip occlusion, the Neuroform(3) and Enterprise stents returned to their original configuration and diameter. Clip application to both also resulted in immediate flow arrest. In contrast, initial clip application to the Pipeline stents did not result in flow arrest, but the second single clip application did. The Pipeline stents were also irreversibly deformed after the experimental protocol, with an average luminal diameter reduction of 26.85% (P < .05). CONCLUSION The Neuroform(3) and Enterprise stents responded favorably to temporary clip application, returning to their original diameter after clip removal and showing no sign of permanent structural modification. The Pipeline flow-diverting stent, however, was irreversibly deformed by clip application. These data indicate that temporary clip application to certain stents is possible. Further in vivo study is required.
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Affiliation(s)
- Randy S Bell
- Neuro Interventional Service, Department of Radiology, Washington Hospital Center, Washington DC, USA.
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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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Wang S, Ding G, Zhang Y, Yang X. Computational haemodynamics in two idealised cerebral wide-necked aneurysms after stent placement. Comput Methods Biomech Biomed Engin 2011; 14:927-37. [DOI: 10.1080/10255842.2010.502531] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Euringer W, Südkamp M, Rylski B, Blanke P. Endovascular Treatment of Multiple HIV-related Aneurysms Using Multilayer Stents. Cardiovasc Intervent Radiol 2011; 35:945-9. [DOI: 10.1007/s00270-011-0269-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 08/18/2011] [Indexed: 10/17/2022]
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Lu G, Huang L, Zhang XL, Wang SZ, Hong Y, Hu Z, Geng DY. Influence of hemodynamic factors on rupture of intracranial aneurysms: patient-specific 3D mirror aneurysms model computational fluid dynamics simulation. AJNR Am J Neuroradiol 2011; 32:1255-61. [PMID: 21757526 PMCID: PMC7966033 DOI: 10.3174/ajnr.a2461] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 11/09/2010] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND PURPOSE Hemodynamics factors play an important role in the rupture of cerebral aneurysms. The purpose of this study was to evaluate the impact of hemodynamic factors on the rupture of the MANs with 3D reconstruction model CFD simulation. MATERIALS AND METHODS RDSA was performed in 9 pairs of intracranial MANs. Each pair was divided into ruptured and unruptured groups. The hemodynamic factors of the aneurysms and their parent arteries were compared. RESULTS There was a significant difference in the WSS at peak systole between the regions of the aneurysms and their parent arteries in the ruptured group (ie, 6.49 ± 3.48 Pa versus 8.78 ± 3.57 Pa, P =.015) but not in the unruptured group (ie, 9.80 ± 4.12 Pa versus 10.17 ± 7.48 Pa, P =.678). The proportion of the low WSS area to the whole area of the aneurysms was 12.20 ± 18.08% in the ruptured group and 3.96 ± 6.91% in the unruptured group; the difference between the 2 groups was statistically significant (P =.015). The OSI was 0.0879 ± 0.0764 in the ruptured group, which was significantly higher than that of the unruptured group (ie, 0.0183 ± 0.0191, P =.008). CONCLUSIONS MANs may be a useful disease model to investigate possible causes linked to ruptured aneurysms. The ruptured aneurysms manifested lower WSS compared with their parent arteries, a higher proportion of the low WSS area to the whole area of aneurysm, and higher OSI compared with the unruptured aneurysms.
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Affiliation(s)
- G Lu
- Shanghai Department of Radiology, Fudan University, Huashan Hospital, Shanghai, China
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Endovascular Management of Complex Renal Artery Aneurysms Using the Multilayer Stent. Cardiovasc Intervent Radiol 2010; 34:637-41. [DOI: 10.1007/s00270-010-0047-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 10/29/2010] [Indexed: 10/18/2022]
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Dorn F, Niedermeyer F, Balasso A, Liepsch D, Liebig T. The effect of stents on intra-aneurysmal hemodynamics: in vitro evaluation of a pulsatile sidewall aneurysm using laser Doppler anemometry. Neuroradiology 2010; 53:267-72. [PMID: 20563572 DOI: 10.1007/s00234-010-0723-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 05/17/2010] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Hemodynamic modification by means of flow diversion is increasingly used for treatment of intracranial aneurysms. Despite of promising results, there is still a paucity of methods to reliably predict long-term success of this technique. Laser Doppler anemometry (LDA) can be used to quantify the influence of stents on intra-aneurysmal flow in vitro. METHODS All experiments were performed with a pulsatile model of a sidewall aneurysm. A physiologic flow was created with a circulatory experimental setup, and a transparent non-Newtonian glycerol-water solution was used to substitute human blood. Flow velocity was measured with a one-component LDA system, recording flow components parallel and perpendicular to the parent vessel. Three different stents (Solitaire, Silk, Phenox flow diverter) were deployed over the aneurysm neck, respectively. RESULTS Flow reduction was 67.59% (inflow zone), 9.65% (dome) and 37.94% (outflow zone) by the Solitaire stent. The Silk stent reduced the flow by 58.15% (inflow zone), 89.06% (dome) and 90.06% (outflow zone). The Phenox flow diverter reduced the flow by 96.76% (inflow zone), 90% (dome) and 90.91% (outflow zone) when positioned with narrow stent struts but increased the velocity of up to seven times compared to the unstented model when placed with loose strut packing in the proximal part of the aneurysm. CONCLUSION LDA is a feasible method to quantify intra-aneurysmal flow and flow reduction efficacy of stents in vitro. Flow reduction was negligible with a standard self-expanding stent. For dedicated flow diverters, it depended both on stent design and on appropriate positioning.
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Affiliation(s)
- Franziska Dorn
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Munich, Germany.
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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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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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Radaelli AG, Augsburger L, Cebral JR, Ohta M, Rüfenacht DA, Balossino R, Benndorf G, Hose DR, Marzo A, Metcalfe R, Mortier P, Mut F, Reymond P, Socci L, Verhegghe B, Frangi AF. Reproducibility of haemodynamical simulations in a subject-specific stented aneurysm model--a report on the Virtual Intracranial Stenting Challenge 2007. J Biomech 2008; 41:2069-81. [PMID: 18582891 DOI: 10.1016/j.jbiomech.2008.04.035] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 04/24/2008] [Accepted: 04/24/2008] [Indexed: 10/21/2022]
Abstract
This paper presents the results of the Virtual Intracranial Stenting Challenge (VISC) 2007, an international initiative whose aim was to establish the reproducibility of state-of-the-art haemodynamical simulation techniques in subject-specific stented models of intracranial aneurysms (IAs). IAs are pathological dilatations of the cerebral artery walls, which are associated with high mortality and morbidity rates due to subarachnoid haemorrhage following rupture. The deployment of a stent as flow diverter has recently been indicated as a promising treatment option, which has the potential to protect the aneurysm by reducing the action of haemodynamical forces and facilitating aneurysm thrombosis. The direct assessment of changes in aneurysm haemodynamics after stent deployment is hampered by limitations in existing imaging techniques and currently requires resorting to numerical simulations. Numerical simulations also have the potential to assist in the personalized selection of an optimal stent design prior to intervention. However, from the current literature it is difficult to assess the level of technological advancement and the reproducibility of haemodynamical predictions in stented patient-specific models. The VISC 2007 initiative engaged in the development of a multicentre-controlled benchmark to analyse differences induced by diverse grid generation and computational fluid dynamics (CFD) technologies. The challenge also represented an opportunity to provide a survey of available technologies currently adopted by international teams from both academic and industrial institutions for constructing computational models of stented aneurysms. The results demonstrate the ability of current strategies in consistently quantifying the performance of three commercial intracranial stents, and contribute to reinforce the confidence in haemodynamical simulation, thus taking a step forward towards the introduction of simulation tools to support diagnostics and interventional planning.
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Affiliation(s)
- A G Radaelli
- Computational Imaging Laboratory, Information and Communication Technologies Department, Universitat Pompeu Fabra, Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.
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LaDisa JF, Olson LE, Douglas HA, Warltier DC, Kersten JR, Pagel PS. Alterations in regional vascular geometry produced by theoretical stent implantation influence distributions of wall shear stress: analysis of a curved coronary artery using 3D computational fluid dynamics modeling. Biomed Eng Online 2006; 5:40. [PMID: 16780592 PMCID: PMC1550410 DOI: 10.1186/1475-925x-5-40] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 06/16/2006] [Indexed: 01/29/2023] Open
Abstract
Background The success of stent implantation in the restoration of blood flow through areas of vascular narrowing is limited by restenosis. Several recent studies have suggested that the local geometric environment created by a deployed stent may influence regional blood flow characteristics and alter distributions of wall shear stress (WSS) after implantation, thereby rendering specific areas of the vessel wall more susceptible to neointimal hyperplasia and restenosis. Stents are most frequently implanted in curved vessels such as the coronary arteries, but most computational studies examining blood flow patterns through stented vessels conducted to date use linear, cylindrical geometric models. It appears highly probable that restenosis occurring after stent implantation in curved arteries also occurs as a consequence of changes in fluid dynamics that are established immediately after stent implantation. Methods In the current investigation, we tested the hypothesis that acute changes in stent-induced regional geometry influence distributions of WSS using 3D coronary artery CFD models implanted with stents that either conformed to or caused straightening of the primary curvature of the left anterior descending coronary artery. WSS obtained at several intervals during the cardiac cycle, time averaged WSS, and WSS gradients were calculated using conventional techniques. Results Implantation of a stent that causes straightening, rather than conforms to the natural curvature of the artery causes a reduction in the radius of curvature and subsequent increase in the Dean number within the stented region. This straightening leads to modest skewing of the velocity profile at the inlet and outlet of the stented region where alterations in indices of WSS are most pronounced. For example, time-averaged WSS in the proximal portion of the stent ranged from 8.91 to 11.7 dynes/cm2 along the pericardial luminal surface and 4.26 to 4.88 dynes/cm2 along the myocardial luminal surface of curved coronary arteries as compared to 8.31 dynes/cm2 observed throughout the stented region of a straight vessel implanted with an equivalent stent. Conclusion The current results predicting large spatial and temporal variations in WSS at specific locations in curved arterial 3D CFD simulations are consistent with clinically observed sites of restenosis. If the findings of this idealized study translate to the clinical situation, the regional geometry established immediately after stent implantation may predispose portions of the stented vessel to a higher risk of neointimal hyperplasia and subsequent restenosis.
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Affiliation(s)
- John F LaDisa
- Department of Pediatrics (Division of Cardiology), Stanford University, Stanford, California, USA
- Department of Anesthesiology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
| | - Lars E Olson
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
| | - Hettrick A Douglas
- Department of Anesthesiology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
| | - David C Warltier
- Department of Anesthesiology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Medicine (Division of Cardiovascular Diseases), the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Pharmacology and Toxicology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
| | - Judy R Kersten
- Department of Anesthesiology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Pharmacology and Toxicology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
| | - Paul S Pagel
- Department of Anesthesiology, the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
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