1
|
Fu Y, Bian X, Zou R, Jin R, Leng X, Fan F, Wei S, Cui X, Xiang J, Guan S. Hemodynamic alterations of flow diverters on aneurysms at the fetal posterior communicating artery: A simulation study using CFD to compare the surpass streamline, pipeline flex, and tubridge devices. J Neuroradiol 2024; 51:74-81. [PMID: 37442272 DOI: 10.1016/j.neurad.2023.07.002] [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] [Received: 12/01/2022] [Revised: 07/03/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023]
Abstract
PURPOSE Traditional flow diverters (FDs) for treating aneurysms at the fetal posterior communicating artery are unsatisfactory. Surpass Streamline is a novel FD with different mesh characteristics; however, the outcomes for such aneurysms remain unclear. This study aimed to compare hemodynamic alterations induced by Surpass Streamline, Pipeline Flex, and Tubridge devices and explore possible strategies for aneurysms at the fetal posterior communicating artery. METHODS Two simulated aneurysms (Case 1, Case 2) were constructed from digital subtraction angiography (DSA). The three FDs were virtually deployed, and hemodynamic analysis based on computational fluid dynamics was performed. Hemodynamic parameters, including the sac-averaged velocity magnitude (Velocity), high-flow volume (HFV), and wall shear stress (WSS), were compared between each FD and the untreated model (control). Surpass Streamline was performed in real life for two aneurysms and the clinical outcomes were collected for analysis. RESULTS Compared to the control, the Surpass resulted in the most significant reduction in flow. In Case 1, the Velocity, HFV, and WSS were reduced by 51.6%, 78.1%, and 64.3%, respectively. In Case 2, the Velocity, HFV, and WSS were reduced by 48.0%, 81.1%, and 65.3%, respectively. Tubridge showed slightly larger changes in hemodynamic parameters than Pipeline. In addition, our analysis suggested that metal coverage was correlated with the WSS, Velocity, and HFV. The postoperative DSA showed that the aneurysm was nearly occluded in Case 1 and decreased in Case 2. CONCLUSION Compared to that with the Pipeline and Tubridge, the Surpass resulted in the greatest reduction in hemodynamic parameters and might be effective for aneurysms at the fetal posterior communicating artery. Virtual FD deployment and computational fluid dynamics analysis may be used to predict the treatment outcomes.
Collapse
Affiliation(s)
- Yu Fu
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xin Bian
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | - Rong Zou
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | - Rongbo Jin
- ArteryFlow Technology Co., Ltd., Hangzhou, China
| | | | - Feng Fan
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Sen Wei
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuan Cui
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | | | - Sheng Guan
- Department of Neurointervention Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
| |
Collapse
|
2
|
Nariai Y, Takigawa T, Kawamura Y, Hyodo A, Suzuki K. Inflow Angle and Height-Width Ratio are Predictors of Incomplete Occlusion at One and Two Years After Flow Diverter Treatment for Small- and Medium-Sized Internal Carotid Artery Aneurysms. World Neurosurg 2023; 180:e716-e728. [PMID: 37821031 DOI: 10.1016/j.wneu.2023.10.014] [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] [Received: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023]
Abstract
OBJECTIVE We investigated the association between the inflow angle of aneurysms and their occlusion status at 1 and 2 years after flow diverter (FD) treatment. METHODS We retrospectively analyzed 42 consecutive patients from a single center with 43 untreated, unruptured internal carotid artery (ICA) proximal to communicating segment, saccular aneurysms sized <12 mm. RESULTS At 1 year posttreatment, the complete occlusion (CO) rate was 58.1%. On univariate analyses, the proportion of inflow angle >90° was significantly lower in the CO group than in the incomplete occlusion group (20.0% VS. 83.3%; P < 0.001). The CO incidence decreased with a height-width (H/W) ratio of <1.2 (P = 0.059). On multivariate analysis, an H/W ratio of <1.2 (odds ratio [OR], 0.076; P = 0.027) and an inflow angle of >90° (OR, 0.020; P = 0.0011) significantly influenced CO at 1 year post FD. At 2 years posttreatment, the CO rate was 76.3% (29/38 cases with available follow-up data). On univariate analyses, in the CO group compared to the incomplete occlusion group, the proportion of H/W ratio <1.2 was significantly lower (P = 0.005) and the proportion of inflow angle >90° was significantly lower (P = 0.021); aneurysm dome size tended to be larger (8.5 mm vs. 7.1 mm; P = 0.080). On multivariate analysis, an H/W ratio <1.2 (OR, 0.042; P = 0.015) and an inflow angle >90° (OR: 0.088; P = 0.031) significantly influenced CO at 2 years post FD. CONCLUSIONS The inflow angle of >90° and H/W ratio <1.2 may significantly influence the CO rate in small- or medium-sized internal carotid artery aneurysms 1 and 2 years post FD.
Collapse
Affiliation(s)
- Yasuhiko Nariai
- Department of Neurosurgery, Dokkyo Medical University Saitama Medical Center, Saitama, Japan.
| | - Tomoji Takigawa
- Department of Neurosurgery, Dokkyo Medical University Saitama Medical Center, Saitama, Japan
| | - Yosuke Kawamura
- Department of Neurosurgery, Dokkyo Medical University Saitama Medical Center, Saitama, Japan
| | - Akio Hyodo
- Department of Neurosurgery, Kamagaya General Hospital, Chiba, Japan
| | - Kensuke Suzuki
- Department of Neurosurgery, Dokkyo Medical University Saitama Medical Center, Saitama, Japan
| |
Collapse
|
3
|
Fujitani S, Tsuruta W, Tomioka A, Ishigami D, Sekine T, Hosoo H, Kamiya Y, Matsumaru Y. Aneurysm Isolation is Associated with Complete Occlusion of Aneurysms After Flow Diverter Treatment. Clin Neuroradiol 2023; 33:1087-1093. [PMID: 37428198 DOI: 10.1007/s00062-023-01312-z] [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] [Received: 01/18/2023] [Accepted: 05/22/2023] [Indexed: 07/11/2023]
Abstract
PURPOSE Some aneurysms remain patent after treatment with flow diverters (FD) due to residual blood flow in the aneurysm. Several studies have proposed that branches and residual flow are associated with delayed aneurysm occlusion. We propose that aneurysm isolation (i.e., the complete disconnection of the aneurysm from surrounding vessels) might be a possible factor facilitating aneurysm occlusion. This study aimed to determine if aneurysm isolation was a factor associated with aneurysm occlusion after FD treatment. METHODS We reviewed 80 internal carotid artery (ICA) aneurysms treated with FDs between October 2014 and April 2021. Aneurysm isolation was assessed in high-resolution cone-beam computed tomograms at the end of each treatment. Aneurysms with incorporated branches and those with connections to other branches due to stent malapposition were deemed to be nonisolated. Other factors, such as patient age, sex, anticoagulant use, aneurysm size, adjunct coil use, and the presence of incorporated branches, were considered. The degree of aneurysm occlusion (complete or incomplete) was assessed by follow-up angiograms 12 months after treatment. RESULTS Complete occlusion was achieved in 57 of 80 aneurysms (71%). Completely occluded aneurysms had a significantly higher ratio of isolation compared to incompletely occluded aneurysms (91.2% vs. 69.6%, P = 0.032). Multivariate logistic regression analysis showed that aneurysm isolation was the sole significant predictor of complete aneurysm occlusion (odds ratio, OR 19.38; 95% confidence interval, CI 2.280-164.657; P = 0.007). CONCLUSION Aneurysm isolation is a significant factor contributing to complete occlusion after FD treatment.
Collapse
Affiliation(s)
- Shigeta Fujitani
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Wataro Tsuruta
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan.
| | - Arisa Tomioka
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Daiichiro Ishigami
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
- Department of Neurosurgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tomokazu Sekine
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
| | - Hisayuki Hosoo
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
- Division of Stroke Prevention and Treatment, Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Yuki Kamiya
- Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
| | - Yuji Matsumaru
- Division of Stroke Prevention and Treatment, Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| |
Collapse
|
4
|
Wang Y, Yang X, Zhu W, Wang X, Yao Y, Lu W, Yang G, Qin L, Liu J, Li M. Verification of software-based preoperative simulation of flow diverters in clinical cases. Interv Neuroradiol 2023; 29:510-519. [PMID: 35505598 PMCID: PMC10549721 DOI: 10.1177/15910199221097264] [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: 11/26/2021] [Accepted: 03/24/2022] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE The authors sought to verify the use of a preoperative simulation software for the treatment of intracranial aneurysms using flow diverters (FDs) based on three-dimensional rotational angiography (3DRA) data. METHODS Based on 3DRA data, the preoperative simulation software (UKNOW) was used to simulate the deployment of virtual FDs. The length and dimensions of virtual and real devices were compared. The deployment plan recommended by the UKNOW software was preliminarily used to complete implantations in the real world. During the experiment, experienced neurointerventional experts were responsible for supervising and judging information such as the length, dimension, and deployment location of the FDs. RESULTS This study retrospectively analyzed the data of 29 patients who received FD treatment. There was no statistical difference between the length of the real device and the virtual device (p = 0.6). The dimensions of FDs recommended by the software were consistent with the dimensions used in 24 out of the 29 real cases. In four of the remaining five cases, neurointerventional experts found that the FD dimensions recommended by the software were superior to those were actually used. Thus, the accuracy rate for FD dimension recommendations by the UKNOW software was 96.6% (28/29). Procedures performed in five cases using deployment plans recommended by the UKNOW software all achieved good postoperative results; the deployment positions of the device were reasonable, and all devices showed good wall adherence. CONCLUSIONS UKNOW software could accurately simulate the length and deployment position of the real FDs and provide suitable device dimensions.
Collapse
Affiliation(s)
- Yixuan Wang
- Department of Neurosurgery, The China-Japan Union Hospital, Jilin University, Changchun, China
| | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wei Zhu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xinlan Wang
- Department of Neurosurgery, The China-Japan Union Hospital, Jilin University, Changchun, China
| | - Yangyang Yao
- UnionStrong (Beijing) Technology Co. Ltd, Beijing, China
| | - Wangsheng Lu
- UnionStrong (Beijing) Technology Co. Ltd, Beijing, China
| | - Guangming Yang
- UnionStrong (Beijing) Technology Co. Ltd, Beijing, China
| | - Lan Qin
- UnionStrong (Beijing) Technology Co. Ltd, Beijing, China
| | - Jian Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Miao Li
- Department of Neurosurgery, The China-Japan Union Hospital, Jilin University, Changchun, China
| |
Collapse
|
5
|
Zhang M, Tian Z, Zhang Y, Zhang Y, Wang K, Leng X, Yang X, Xiang J, Liu J. How to perform intra-aneurysmal coil embolization after Pipeline deployment: a study from a hemodynamic viewpoint. J Neurointerv Surg 2023; 15:157-162. [PMID: 35135848 DOI: 10.1136/neurintsurg-2021-018361] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/23/2022] [Indexed: 01/14/2023]
Abstract
BACKGROUND Pipeline embolization device (PED) deployment combined with coil therapy for large complex intracranial aneurysms is effective and considered superior to PED deployment alone. However, the optimal strategy for use of coils remains unclear. We used patient-specific aneurysm models and finite element analysis to determine the ideal packing density of coils after PED placement. METHODS Finite element analysis was used to provide a higher-fidelity model for accurate post-treatment computational fluid dynamics analysis to simulate the real therapeutic process of PED and all coils. We then calculated and analyzed the reduction ratio of velocity to identify the hemodynamic change during PED deployment and each coil embolization. RESULTS Sixteen consecutive patients underwent PED plus coil procedures to treat internal carotid artery intracranial aneurysms. After PED deployment, the intra-aneurysmal flow velocity significantly decreased (15.3 vs 10.0 cm/s; p<0.001). When the first coil was inserted, the flow velocity in the aneurysm further decreased and the reduction was significant (10.0 vs 5.3 cm/s; p<0.001). Analysis of covariance showed that the effect of the reduction ratio of velocity of the second coil was significantly lower than that of the first coil (p<0.001)-that is, when the packing density increased to 7.06%, the addition of coils produced no further hemodynamic effect. CONCLUSION Adjunct coiling could improve the post-PED hemodynamic environment in treated intracranial aneurysms. However, dense packing is not necessary because the intra-aneurysmal hemodynamics tend to stabilize as the packing density reaches an average of 7.06% or after insertion of the second coil.
Collapse
Affiliation(s)
- Mingqi Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhongbin Tian
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Yisen Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Ying Zhang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Kun Wang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | | | - Xinjian Yang
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | | | - Jian Liu
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
6
|
Chen S, Bai B, Lv N, Cheng Y, Ji B. Hemodynamic analysis and implantation strategies of delayed intracranial aneurysm rupture after flow diverter treatment. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1735. [PMID: 35071429 PMCID: PMC8743709 DOI: 10.21037/atm-21-5939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/02/2021] [Indexed: 01/16/2023]
Abstract
BACKGROUND Delayed aneurysm rupture after flow diverters (FDs) is a serious complication which mechanism remains unclear. The hemodynamics of FDs with proximal or distal densification implantation strategies have rarely been reported. In this study, we investigated not only the hemodynamic factors involved in postoperative rupture, but also the hemodynamic effects of different FDs implantation strategies on avoiding this complication. METHODS We selected 2 internal carotid artery (ICA) aneurysms with similar morphological characteristics, both of which were treated with FDs but had opposite therapeutic outcomes (Case 1, ruptured after FD treatment; Case 2, recovered). The FDs strategies we designed were strategy A [with homogeneous 30% metal coverage ratio (MCR)], strategy B (with distal densification of 40% and proximal 30% MCR) and strategy C (with proximal densification of 40% and distal 30% MCR). Virtually FDs deployment and computational fluid dynamics (CFD) method were performed to simulate FDs implantation strategies and analyze the hemodynamics associated with postoperative rupture. RESULTS After FDs implantation, the velocity of blood entering the aneurysm decreased (Case 1, 25.4%; Case 2, 30.6%), but the inflow jet impingement still existed in Case 1. The overall WSS decreased similarly in both cases, but the high WSS region hardly diminished in Case 1. For overall wall pressure, Case 2 decreased slightly but increased in Case 1. Of the three FDs implantation strategies, strategy C had the best hemodynamic effects, including the maximum blood velocity reduction and a tendency to form a more stable flow pattern, the maximum reduction rate of overall WSS and the effective diminish of high WSS area as well as the overall decrease of wall pressure. CONCLUSIONS Not significant decrease of blood flow velocity entering the aneurysm adding persistent impact of inflow jet impingement, high WSS area that did not diminish and abnormal increase of pressure on the aneurysm wall may be causative of postoperative rupture and bleeding of ICA aneurysms. In addition, the hemodynamic effects were favorable when the FD was improved to proximal densification, which may reduce the risk of delayed aneurysm rupture following FDs treatment. KEYWORDS Delayed rupture; flow diverter (FD); computational fluid dynamics (CFD); intracranial aneurysm (IAs); internal carotid artery (ICA).
Collapse
Affiliation(s)
- Shiyao Chen
- Shanghai Interventional Medical Device Engineering Technology Research Center, University of Shanghai for Science and Technology, Shanghai, China
| | - Bin Bai
- Shanghai Interventional Medical Device Engineering Technology Research Center, University of Shanghai for Science and Technology, Shanghai, China
| | - Nan Lv
- Department of Neurosurgery, First Affiliated Hospital of Naval Military Medical University, Changhai Hospital of Shanghai, Shanghai, China
| | - Yunzhang Cheng
- Shanghai Interventional Medical Device Engineering Technology Research Center, University of Shanghai for Science and Technology, Shanghai, China
| | - Bin Ji
- Department of Radiology, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
| |
Collapse
|
7
|
Chassagne F, Barbour MC, Chivukula VK, Machicoane N, Kim LJ, Levitt MR, Aliseda A. The effect of Dean, Reynolds, and Womersley number on the flow in a spherical cavity on a curved round pipe. Part 1. Fluid mechanics in the cavity as a canonical flow representing intracranial aneurysms. JOURNAL OF FLUID MECHANICS 2021; 915:A123. [PMID: 34024939 PMCID: PMC8136084 DOI: 10.1017/jfm.2020.1114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Flow in side-wall cerebral aneurysms can be ideally modelled as the combination of flow over a spherical cavity and flow in a curved circular pipe, two canonical flows. Flow in a curved pipe is known to depend on the Dean number De, combining the effects of Reynolds number, Re, and of the curvature along the pipe centreline, κ. Pulsatility in the flow introduces a dependency on the Womersley number Wo. Using stereo PIV measurements, this study investigated the effect of these three key non-dimensional parameters, by modifying pipe curvature (De), flow-rate (Re), and pulsatility frequency (Wo), on the flow patterns in a spherical cavity. A single counter-rotating vortex was observed in the cavity for all values of pipe curvature κ and Re, for both steady and pulsatile inflow conditions. Increasing the pipe curvature impacted both the flow patterns in the pipe and the cavity, by shifting the velocity profile towards the cavity opening and increasing the flow rate into the cavity. The circulation in the cavity was found to collapse well with only the Dean number, for both steady and pulsatile inflows. For pulsatile inflow, the counter-rotating vortex was unstable and the location of its centre over time was impacted by the curvature of the pipe, as well as the Re and the Wo in the freestream. The circulation in the cavity was higher for steady inflow than for the equivalent average Reynolds and Dean number pulsatile inflow, with very limited impact of the Womersley in the range studied.
Collapse
Affiliation(s)
- Fanette Chassagne
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98105, USA
| | - Michael C. Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98105, USA
| | - Venkat K. Chivukula
- Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA
| | | | - Louis J. Kim
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
- Department of Radiology, University of Washington, Seattle, WA 98107, USA
| | - Michael R. Levitt
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98105, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
- Department of Radiology, University of Washington, Seattle, WA 98107, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98105, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
| |
Collapse
|
8
|
Barbour MC, Chassagne F, Chivukula VK, Machicoane N, Kim LJ, Levitt MR, Aliseda A. The effect of Dean, Reynolds and Womersley numbers on the flow in a spherical cavity on a curved round pipe. Part 2. The haemodynamics of intracranial aneurysms treated with flow-diverting stents. JOURNAL OF FLUID MECHANICS 2021; 915:A124. [PMID: 34658417 PMCID: PMC8519511 DOI: 10.1017/jfm.2020.1115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The flow in a spherical cavity on a curved round pipe is a canonical flow that describes well the flow inside a sidewall aneurysm on an intracranial artery. Intracranial aneurysms are often treated with a flow-diverting stent (FDS), a low-porosity metal mesh that covers the entrance to the cavity, to reduce blood flow into the aneurysm sac and exclude it from mechanical stresses imposed by the blood flow. Successful treatment is highly dependent on the degree of reduction of flow inside the cavity, and the resulting altered fluid mechanics inside the aneurysm following treatment. Using stereoscopic particle image velocimetry, we characterize the fluid mechanics in a canonical configuration representative of an intracranial aneurysm treated with a FDS: a spherical cavity on the side of a curved round pipe covered with a metal mesh formed by an actual medical FDS. This porous mesh coverage is the focus of Part 2 of the paper, characterizing the effects of parent vessel Re, De and pulsatility, Wo, on the fluid dynamics, compared with the canonical configuration with no impediments to flow into the cavity that is described in Part 1 (Chassagne et al., J. Fluid Mech., vol. 915, 2021, A123). Coverage with a FDS markedly reduces the flow Re in the aneurysmal cavity, creating a viscous-dominated flow environment despite the parent vessel Re > 100. Under steady flow conditions, the topology that forms inside the cavity is shown to be a function of the parent vessel De. At low values of De, flow enters the cavity at the leading edge and remains attached to the wall before exiting at the trailing edge, a novel behaviour that was not found under any conditions of the high-Re, unimpeded cavity flow described in Part 1. Under these conditions, flow in the cavity co-rotates with the direction of the free-stream flow, similar to Stokes flow in a cavity. As De increases, the flow along the leading edge begins to separate, and the recirculation zone grows with increasing De, until, above De ≈ 180, the flow inside the cavity is fully recirculating, counter-rotating with respect to the free-stream flow. Under pulsatile flow conditions, the vortex inside the cavity progresses through the same cycle - switching from attached and co-rotating with the free-stream flow at the beginning of the cycle (low velocity and positive acceleration) to separated and counter-rotating as De reaches a critical value. The location of separation within the harmonic cycle is shown to be a function of both De and Wo. The values of aneurysmal cavity Re based on both the average velocity and the circulation inside the cavity are shown to increase with increasing values of De, while Wo is shown to have little influence on the time-averaged metrics. As De increases, the strength of the secondary flow in the parent vessel grows, due to the inertial instability in the curved pipe, and the flow rate entering the cavity increases. Thus, the effectiveness of FDS treatment to exclude the aneurysmal cavity from the haemodynamic stresses is compromised for aneurysms located on high-curvature arteries, i.e. vessels with high De, and this can be a fluid mechanics criterion to guide treatment selection.
Collapse
Affiliation(s)
- Michael C. Barbour
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98107, USA
| | - Fanette Chassagne
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98107, USA
| | - Venkat K. Chivukula
- Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA
| | | | - Louis J. Kim
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
- Department of Radiology, University of Washington, Seattle, WA 98107, USA
| | - Michael R. Levitt
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98107, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
- Department of Radiology, University of Washington, Seattle, WA 98107, USA
| | - Alberto Aliseda
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98107, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA 98107, USA
| |
Collapse
|
9
|
Chaohui L, Yu ZG, Kai H. Balloon-Assisted Coils Embolization for Ophthalmic Segment Aneurysms of the Internal Carotid Artery. Front Neurol 2021; 12:658661. [PMID: 33935955 PMCID: PMC8081857 DOI: 10.3389/fneur.2021.658661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/10/2021] [Indexed: 11/29/2022] Open
Abstract
Objective: To explore the role of balloon-assisted coils technique for ophthalmic segment aneurysms (OSAS). Methods: Clinical data of 30 patients with OSAS were reviewed between December 2017 and December 2018. OSAS were defined as arising from the internal carotid artery (ICA), reaching from the distal dural ring to the origin of the posterior communicating artery. OSAS were classified into four types based on the angiographic findings. The balloon-assisted coils technique was used for the embolization of aneurysms. The duration of balloon inflation cycles, as well as difficulty and complications during the embolization procedure, were recorded. The immediate angiographic results were evaluated according to the Raymond scale. Clinical results were evaluated based on the MRS score. Follow-ups were performed at 18 months post-embolization by DSA or MRA at our institution. Results: Thirty-two aneurysms in 30 patients were detected by digital subtraction angiography (DSA), which included 30 unruptured and two ruptured cases. The patients with ruptured aneurysms were grade II status according to the Hunt-Hess scale. Three cases were type A, nine cases were type B, 17 cases were type C, and three cases were type D. According to aneurysm size, there were 19 cases of small, 11 cases of medium, two cases of large aneurysm. Thirty-two aneurysms were successfully embolized in 30 patients by balloon-assisted coils technique. The ophthalmic artery could be protected by an engorged balloon in the procedure, especially for type A aneurysms. Considering that type D aneurysm arises from the side-wall of the artery and near to tortuous ICA siphon, the balloon catheter was inflated to stabilize the microcatheter allowing for overinflation when necessary. The average duration of balloon dilatation was 4 min, and the average time was 2.5 times. Raymond class was one in 28 aneurysms and two in four aneurysms according to the immediate post-embolization angiographic results. All the patients achieved good clinical effects, except for one patient who presented with brain ischemia resulting in dizziness and contralateral limb weakness for 10 h due to prolonged temporary clamping of the responsible ICA. The follow-up angiography results were satisfactory at 18 months post-embolization. Conclusion: OSAS endovascular treatment with balloon-assisted coils has different advantages in a different classification. The technique is safe, effective, and relatively inexpensive, especially for small and medium OSAS.
Collapse
Affiliation(s)
- Liang Chaohui
- Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Zhang Guang Yu
- Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Hou Kai
- Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| |
Collapse
|
10
|
|