Combinational Optimization of Strut Placement for Intracranial Stent Using a Realistic Aneurysm

Anzai, Hitomi; Chopard, Bastien; Ohta, Makoto

doi:10.4236/jfcmv.2014.22009

Cited by 6 publications

(4 citation statements)

References 37 publications

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“…e study of hemodynamics provides an effective method for us to solve the abovementioned problems. Previous studies have pointed out that hemodynamic study of applying CABGs to treat other diseases such as coronary stenosis by using computational fluid dynamics (CFD), which has attracted wide attention in recent years and has many applications in the vascular field [16][17][18], has made progress. Also, those research studies confirm that surgical outcomes correlate with some important hemodynamic characteristics including mass flow rate, wall shear stress (WSS), and oscillatory shear index (OSI) [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

A Hemodynamic-Based Evaluation of Applying Different Types of Coronary Artery Bypass Grafts to Coronary Artery Aneurysms

et al. 2020

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Coronary artery bypass grafts (CABGs), including saphenous vein grafts (SVGs) or left internal mammary artery (LIMA) grafts, are recently applied to treat coronary artery aneurysm (CAA). Surgical outcomes are considered to be related to surgical strategies (types of the bypass graft and whether CAA ligated or not) and the size of the CAA (usually characterized by diameter). However, the understanding of the relationship between the surgical outcomes and the abovementioned factors is limited. Previous studies related to CABG treatments have shown hemodynamic studies could help evaluate surgical outcomes through graft mass flow rate, wall shear stress (WSS), and oscillatory shear index (OSI). It is believed that the hemodynamic study of applying CABGs to CAA, which is not studied yet, could help us understand the different CABG surgeries. The aim of the study was to evaluate the hemodynamic differences among different surgical methods. To do this, eight three-dimensional models were constructed, representing application of SVGs and LIMA grafts to CAAs (whether ligated or not) with diameters two, three, and five times the normal diameter, to perform computational fluid dynamics (CFD) simulation. The lumped-parameter model (LPM) was coupled to the boundary of the 3D models which increase the complexity of the simulation, but it can ensure the stability of the simulation boundary conditions. The results show that SVG (no matter whether ligated or not) hemodynamic characteristics are positive, with an average high graft mass flow rate of 70 ml/min, an average WSS of 0.479 Pa, and a low OSI of 0.001. LIMA with CAA ligation has the same characteristics with higher WSS (average 1.701 Pa). The hemodynamic characteristics of LIMA without CAA ligation are negative, including high reverse mass flow rate and high OSI (0.367). The results indicate that the surgical outcomes of LIMA with CAA ligation are likely to be the best among these models. The surgical outcomes of LIMA without CAA ligation seem to be undesirable due to the high reverse mass flow and high OSI. The CAA diameter may not have a significant effect on surgical outcomes.

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Section: Introductionmentioning

confidence: 99%

A Hemodynamic-Based Evaluation of Applying Different Types of Coronary Artery Bypass Grafts to Coronary Artery Aneurysms

et al. 2020

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“…Anzai et al advocates that BOI, which is visualized as a region of streamlines entering an aneurysm, is the region affecting circulation in an aneurysm [11]. We regard BOI as being associated with inflow rate ratio, WSS ratio and mean OSI ratio.…”

Section: F Mori Et Al / Changes In Blood Flow Due To Stented Parentmentioning

confidence: 95%

“…Moreover, the selfexpandable stent is most often employed for the treatment of cerebral aneurysms and is thought to reduce flow due to its characteristics of low porosity and fine struts [5]. Zanaty It was recently determined that flow reduction is caused by the following events: 1) the configuration of the parent artery [8,9], 2) stent placement [10,11] and 3) parent artery expansion [12]. Zanaty It was recently determined that flow reduction is caused by the following events: 1) the configuration of the parent artery [8,9], 2) stent placement [10,11] and 3) parent artery expansion [12].…”

Section: Introductionmentioning

confidence: 99%

Changes in blood flow due to stented parent artery expansion in an intracranial aneurysm

Mori

Ohta

Matsuzawa

2014

THC

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BACKGROUND: Stent placement is thought to obstruct the inflow of blood to an aneurysm. However, we introduced parent artery expansion and demonstrated that this may reduce the blood flow by the stent. In our previous study using idealized shapes, the results showed that flow reduction was greater than 22.2%, even if the expansion rate was only 6%. Furthermore, the parent artery expansion is predominantly caused by the effect of flow reduction as compared to that of flow reduction due to the obstruction of flow under stent placement. However, a realistic shape is complex and the blood flow also becomes complex flow. It is not understood whether the results of flow in the idealized shape are reflective of flow from a realistic 3D model. Therefore, we examined the effect of parent artery expansion using a realistic model. OBJECTIVE: The aim is to clarify the effects of parent artery expansion on inflow rate, wall shear stress, and oscillatory shear index. METHODS: We used a patient-specific geometry of a human internal carotid artery with an aneurysm. The geometry of parent artery expansion due to oversized stent constructed based on the voronoi diagram. We performed calculations in the unsteady-state situations using constructed models. RESULTS: The complexity of the flow in the aneurysm decreases in case of expanded parent artery. The inflow rate decreases by 33.6% immediately after parent artery expansion alone without a stent. The effect of the parent artery expansion on flow reduction is larger than that of the obstruction flow by stent placement. In addition, wall shear stress and oscillatory shear index on the aneurysm wall decrease by change in blood flow due to the parent artery expansion. CONCLUSION: The effects of the parent artery expansion in a realistic aneurysm model with different stent lengths were evaluated on the basis of a numerical simulation. Although the flow was complex, the parent artery expansion with stent reduces the inflow to the aneurysm and wall shear stress and oscillatory shear index on the aneurysm. Therefore, we suggest that changes in the blood flow because of the parent artery expansion may be identified and, sometimes, is more effective than the obstruction flow due to the stent placement.

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“…CFD has been used widely in the research of vascular diseases in recent years [14][15][16] and can be used to estimate important hemodynamic parameters including mass flow, WSS, OSI, and RRT. e mass-flow rate can usually be calculated based on speed measurement using non-invasive ultrasonic velocimetry.…”

Section: Introductionmentioning

confidence: 99%

Hemodynamic-Based Evaluation on Thrombosis Risk of Fusiform Coronary Artery Aneurysms Using Computational Fluid Dynamic Simulation Method

et al. 2020

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Coronary artery aneurysms (CAAs) have been reported to associate with an increased risk for thrombosis. Distinct to the brain aneurysm, which can cause a rupture, CAA’s threat is more about its potential to induce thrombosis, leading to myocardial infarction. Case reports suggest that thrombosis risk varied with the different CAA diameters and hemodynamics effects (usually wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT)) may relate to the thrombosis risk. However, currently, due to the rareness of the disease, there is limited knowledge of the hemodynamics effects of CAA. The aim of the study was to estimate the relationship between hemodynamic effects and different diameters of CAAs. Computational fluid dynamics (CFD) provides a noninvasive means of hemodynamic research. Four three-dimensional models were constructed, representing coronary arteries with a normal diameter (1x) and CAAs with diameters two (2x), three (3x), and five times (5x) that of the normal diameter. A lumped parameter model (LPM) which can capture the feature of coronary blood flow supplied the boundary conditions. WSS in the aneurysm decreased 97.7% apparently from 3.51 Pa (1x) to 0.08 Pa (5x). OSI and RRT in the aneurysm were increased apparently by two orders of magnitude from 0.01 (1x) to 0.30 (5x), and from 0.38 Pa−1 (1x) to 51.59 Pa−1 (5x), separately. Changes in the local volume of the CAA resulted in dramatic changes in local hemodynamic parameters. The findings demonstrated that thrombosis risk increased with increasing diameter and was strongly exacerbated at larger diameters of CAA. The 2x model exhibited the lowest thrombosis risk among the models, suggesting the low-damage (medication) treatment may work. High-damage (surgery) treatment may need to be considered when CAA diameter is 3 times or higher. This diameter classification method may be a good example for constructing a more complex hemodynamic-based risk stratification method and could support clinical decision-making in the assessment of CAA.

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Combinational Optimization of Strut Placement for Intracranial Stent Using a Realistic Aneurysm

Cited by 6 publications

References 37 publications

A Hemodynamic-Based Evaluation of Applying Different Types of Coronary Artery Bypass Grafts to Coronary Artery Aneurysms

A Hemodynamic-Based Evaluation of Applying Different Types of Coronary Artery Bypass Grafts to Coronary Artery Aneurysms

Changes in blood flow due to stented parent artery expansion in an intracranial aneurysm

Hemodynamic-Based Evaluation on Thrombosis Risk of Fusiform Coronary Artery Aneurysms Using Computational Fluid Dynamic Simulation Method

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