Effect of Local Coil Density on Blood Flow Stagnation in Densely Coiled Cerebral Aneurysms: A Computational Study Using a Cartesian Grid Method

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Tomohiro Otani ◽  
Takuya Shindo ◽  
Satoshi Ii ◽  
Masayuki Hirata ◽  
Shigeo Wada
Keyword(s):  
Blood Flow ◽  
Computational Study ◽  
Grid Method ◽  
Neck Region ◽  
Cartesian Grid ◽  
Dense Packing ◽  
Patient Specific ◽  
Local Flow ◽  
Cartesian Grid Method ◽  
Flow Stagnation

Aneurysm recurrence is the most critical concern following coil embolization of a cerebral aneurysm. Adequate packing density (PD) and coil uniformity are believed necessary to achieve sufficient flow stagnation, which decreases the risk of aneurysm recurrence. The effect of coil distribution on the extent of flow stagnation, however, especially in cases of dense packing (high PD), has received less attention. Thus, the cause of aneurysm recurrence despite dense packing is still an open question. The primary aim of this study is to evaluate the effect of local coil density on the extent of blood flow stagnation in densely coiled aneurysms. For this purpose, we developed a robust computational framework to determine blood flow using a Cartesian grid method, by which the complex fluid pathways in coiled aneurysms could be flexibly treated using an implicit function. This tool allowed us to conduct blood flow analyses in two patient-specific geometries with 50 coil distribution patterns in each aneurysm at clinically adequate PD. The results demonstrated that dense packing in the aneurysm may not necessarily block completely the inflow into the aneurysm and local flow that formed in the neck region, whose strength was inversely related to this local PD. This finding suggests that local coil density in the neck region still plays an important role in disturbing the remaining local flow, which possibly prevents thrombus formation in a whole aneurysm sac, increasing the risk of aneurysm regrowth and subsequent recurrence.

Abstract 566: Experimental Investigation of Blood Flow in the Femoral Bifurcated Artery

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Azadeh Lotfi ◽  
Zachary Lawler ◽  
Omar Jan ◽  
Tracie Barber ◽  
Anne Simmons
Keyword(s):  
Blood Flow ◽  
Additional Treatment ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Local Flow ◽  
Micro Piv ◽  
Stent Restenosis ◽  
Tibial Arteries ◽  
Hemodynamic Disturbance ◽  
Good Patency

Stent implantation is one of the most widely used interventional treatments for arterial stenosis which occurs predominantly due to atherosclerosis. Although stent placement can ensure very good patency of the lumen, stent-induced hemodynamic disturbance, which can lead to further stenosis, still remains a common clinical complication. This study investigates the degree of hemodynamic disturbance induced by stenting an idealized bifurcated popliteal artery, which branches into the anterior and posterior tibial arteries, and is known as a site prone to atherosclerosis. Both stent-free and stented bifurcated arteries were examined, and the local flow patterns analysed for the comparative disturbance through the use of Micro Particle Image Velocity (micro-PIV) system. A life-size model of the artery was reconstructed using dimensions obtained from a patient specific MRI scan. The experiments were conducted under steady flow conditions, and the flow rates across the bifurcation were visualized and measured using the micro-PIV system. It was shown that hemodynamic disturbances induced by the blood flow over the stent can further disrupt the arterial wall downstream of the stent causing further downstream vascular damage in addition to the in-stent restenosis. This downstream vascular disruption may require additional treatment depending on the type and severity of the damage. The results also support the hypothesis that links certain flow dynamic behaviour with the development of early intimal thickening, as the near wall low fluid momentum regions are found at locations where thickening was localized in bifurcated arteries in clinical studies.

Cartesian Grid Method for Moderate-Reynolds-Number Flows Around Complex Moving Objects

AIAA Journal ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Jo-Einar Emblemsvag ◽  
Ryuta Suzuki ◽  
Graham V. Candler
Keyword(s):  
Reynolds Number ◽  
Moving Objects ◽  
Grid Method ◽  
Cartesian Grid ◽  
Cartesian Grid Method ◽  
Moderate Reynolds Number ◽  
Reynolds Number Flows

Development of Cooling Structures for Blu-Ray Disc Compatible Optical Disc Drives Using Computational Fluid Dynamics Based on Cartesian Grid Method

2007 ◽  
Author(s):  
Nobuyuki Isoshima ◽  
Takayuki Fujimoto ◽  
Yukinobu Abe ◽  
Masatoshi Watanabe ◽  
Yoshiaki Yamauchi ◽  
...  
Keyword(s):  
Laser Diode ◽  
High Speed ◽  
High Performance ◽  
Flow Simulation ◽  
Grid Method ◽  
Ambient Air ◽  
Cartesian Grid ◽  
Optical Disc ◽  
Rotating Disc ◽  
Cartesian Grid Method

High-performance, simple cooling structures for optical disc drives compatible with the Blu-ray disc (BD) were developed using unsteady numerical flow simulation based on the Cartesian grid method. In the new structure, an additional hole in the tray outside of the disc induced a secondary upward flow, which is caused by a pressure difference and rotating-disc flow. The secondary flow decreases the ambient air-temperature of the laser diode below the hole, and furthermore it increases the velocity around the laser diode and enhances the heat transfer rate. The experimental results indicate that the cooling effect of the laser diode increases, and the disc vibration is not influenced by the additional hole in the tray. The cooling structures are applied to the so-called super-multi BD drive, which achieved 4X high-speed recording for the first time in the industry.

Computational Study on the Effects of Peripheral Vessel Network on Blood Flow in the Arterial Circle of Willis

2007 ◽  
Author(s):  
Shigefumi Tokuda ◽  
Takeshi Unemura ◽  
Marie Oshima
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Vascular System ◽  
Computational Study ◽  
Circulatory System ◽  
Biological Data ◽  
Patient Specific ◽  
Peripheral Vessel

Cerebrovascular disorder such as subarachnoid hemorrhage (SAH) is 3rd position of the cause of death in Japan [1]. Its initiation and growth are reported to depend on hemodynamic factors, particularly on wall shear stress or blood pressure induced by blood flow. In order to investigate the information on the hemodynamic quantities in the cerebral vascular system, the authors have been developing a computational tool using patient-specific modeling and numerical simulation [2]. In order to achieve an in vivo simulation of living organisms, it is important to apply appropriate physiological conditions such as physical properties, models, and boundary conditions. Generally, the numerical simulation using a patient-specific model is conducted for a localized region near the research target. Although the analysis region is only a part of the circulatory system, the simulation has to include the effects from the entire circulatory system. Many studies have carried out to derive the boundary conditions to model in vivo environment [3–5]. However, it is not easy to obtain the biological data of cerebral arteries due to head capsule.

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