Hemodynamic features of offending vessels at neurovascular contact in patients with trigeminal neuralgia and hemifacial spasm.
Satoh T, Yagi T, Onoda K, Kameda M, Sasaki T, Ichikawa T, Date I
Journal of neurosurgery
1
-
7
2018.07
[Refereed]
[International journal]
View Summary
OBJECTIVEOffending vessels at the site of neurovascular contact (NVC) in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) may have specific hemodynamic features. The purpose of this study was to investigate the wall shear stress (WSS) of offending vessels at NVCs by conducting a computational fluid dynamics (CFD) analysis.METHODSThe authors retrospectively analyzed the cases of 20 patients (10 with TN and 10 with HFS) evaluated by 3D CT angiography and used the imaging findings for analysis of the hemodynamic parameters. The 3D CFD images were directly compared with the NVCs determined by simulated multifusion images of CT angiogram and MR cisternogram, and operative photos. The magnitudes of the WSS (WSSm) at the proximal (WSSm-p), just-beginning (WSSm-j), contact site (WSSm-s), and distal (WSSm-d) areas of each NVC were analyzed. The ratios of the WSSm-j, WSSm-s, and WSSm-d areas to the WSSm-p area were calculated individually. The direction of the WSS (WSSv) and its temporal variation (WSSvV) were depicted and morphologically compared with the NVC confirmed by simulated images and operative findings.RESULTSThe ratios of WSSm at the just-beginning and the contact site to the proximal area of the NVCs (WSSm-j/WSSm-p and WSSm-s/WSSm-p) were both significantly higher than that at the distal area (WSSm-d/WSSm-p) (p < 0.05). The WSSv and WSSvV at the NVCs showed small variation in a single cardiac cycle, especially along the areas that were in contact with the affected nerve.CONCLUSIONSAreas of relatively high WSSm and temporal variation of WSSm (WSSmV) were observed at the NVCs. Less mobility of the WSSv and WSSvV was detected along the side of the vessels in contact with the nerves. These findings may be consistent with the actual area of the NVC. Hemodynamic features of the site of NVC can be added to the preoperative simulation for MVD surgery, which may be useful for the diagnosis and treatment planning of TN and HFS.
Background. - Recent reports have revealed a worsening of aneurysm occlusion between WEB treatment baseline and angiographic follow-up due to "compression" of `the device. Objective. - We utilized computational fluid dynamics (CFD) in order to determine whether the underlying mechanism of this worsening is flow related. Methods. - We included data from all consecutive patients treated in our institution with a WEB for unruptured aneurysms located either at the middle cerebral artery or basilar tip. The CFD study was performed using pre-operative 3D rotational angiography. From digital subtraction follow-up angiographies patients were dichotomized into two groups: one with WEB "compression" and one without. We performed statistical analyses to determine a potential correlation between WEB compression and CFD inflow ratio. Results. - Between July 2012 and June 2015, a total of 22 unruptured middle cerebral artery or basilar tip aneurysms were treated with a WEB device in our department. Three patients were excluded from the analysis and the mean follow-up period was 17 months. Eleven WEBs presented "compression" during follow-up. Interestingly, device "compression" was statistically correlated to the CFD inflow ratio (P=0.018), although not to aneurysm volume, aspect ratio or neck size. Conclusion. - The mechanisms underlying the worsening of aneurysm occlusion in WEB-treated patients due to device compression are most likely complex as well as multifactorial. However, it is apparent from our pilot study that a high arterial inflow is, at least, partially involved. Further theoretical and animal research studies are needed to increase our understanding of this phenomenon. (C) 2017 Elsevier Masson SAS. All rights reserved.
Communications in Computer and Information Science
761
95
-
103
2017
[Refereed]
View Summary
Cerebral aneurysm is known to initiate at the cerebral artery bifurcation. The pathological mechanism of cerebral aneurysm awaits further understanding especially on its initiation. This study sought to elucidate the three-dimensional structure of cerebral vascular bifurcations with and without aneurysms using human cadavers. The two cases had aneurysmal initiations out of total 7 cases. The studied structure was intimal hyperplasia, tunica media and internal elastic lamina, which were recognized by elastica masson staining. The results showed that the non-existence of tunica media and internal elastic lamina was found in the lesion without aneurysm. The non-existence of intimal hyperplasia was only found in the lesion with aneurysm. These data suggest that the formation of intimal hyperplasia may be related with the initiation of aneurysm. We regarded the boundary of existence arteriosclerosis as the position for new arteriosclerosis occurs and thought the direction of new arteriosclerosis grows would influence whether the cerebral aneurysm initiates or not.
The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME
2016
(
0
)
_1E41
-
1_-_1E41-4_
2016
[Refereed]
View Summary
Cerebral revascularization is a general surgery for vascular lesions. Operative procedures are decided based on surgeon's experience, however unpredictable complications are still a problem. The aim of our study is to predict complications before operation by identifying the mechanism of cerebral hemodynamics adaptations. It is considered that blood flow is regulated for meeting demand of tissue cells. There is a little study about the relationship between blood flow in cerebral arteries and cerebral demand. In this study, the total of flow rate in both sides internal carotid arteries and basilar artery is 'supply blood flow', and gray matter volume (V_G) and white matter volume (V_W) are multiplied by each literature cerebral blood flow (k_G, k_W) to calculate 'demand blood flow' (V_G・K_G+V_W・K_W). For 14 healthy volunteers and 2 patients (aneurysm and ischemic), the ratio of difference between demand and supply blood flow on the basis of supply values are studied. As the result, difference between supply blood flow and demand blood flow is -11.3% in healthy subjects. In a case of aneurysm, difference rate is low before and after surgery. In a case of ischemic, there is a high difference rate (59.1%). However, difference becomes lower (12.1%) by supply blood flow increase after operation. It is suggested that difference rate is available for diagnosis of ischemic.
The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME
2016
(
0
)
_1E41
-
1_-_1E41-4_
2016
[Refereed]
View Summary
Cerebral revascularization is a general surgery for vascular lesions. Operative procedures are decided based on surgeon's experience, however unpredictable complications are still a problem. The aim of our study is to predict complications before operation by identifying the mechanism of cerebral hemodynamics adaptations. It is considered that blood flow is regulated for meeting demand of tissue cells. There is a little study about the relationship between blood flow in cerebral arteries and cerebral demand. In this study, the total of flow rate in both sides internal carotid arteries and basilar artery is 'supply blood flow', and gray matter volume (V_G) and white matter volume (V_W) are multiplied by each literature cerebral blood flow (k_G, k_W) to calculate 'demand blood flow' (V_G・K_G+V_W・K_W). For 14 healthy volunteers and 2 patients (aneurysm and ischemic), the ratio of difference between demand and supply blood flow on the basis of supply values are studied. As the result, difference between supply blood flow and demand blood flow is -11.3% in healthy subjects. In a case of aneurysm, difference rate is low before and after surgery. In a case of ischemic, there is a high difference rate (59.1%). However, difference becomes lower (12.1%) by supply blood flow increase after operation. It is suggested that difference rate is available for diagnosis of ischemic.
Controlling sheer stress in a suspension culture using coquette, flow for efficient proliferation of HEK 293 cells
Zin N, Sakaguchi K, Haraguchi Y, Yagi T, Shimizu T, Umezu M
Fluid Mechanics Open Access
3
(
1
)
2016
Pathological engineering analysis of human unruptured cerebral aneurysms for investigation of relationship between hemodynamic stress and smooth muscle cells
Tobe Y, Yagi T, Kawamura K, Umezu M
Proceedings of the ICBME 2016
28
2016
[Refereed]
Proposal of mathematical auto-regulation model for cerebral blood flow rate prediction of cerebral bypass surgery
Takanishi K, Yagi T, Umezu M
Proceedings of the ICBME 2016
2016
[Refereed]
Study of the consistency of wall shear stress in healthy major human cerebral arteries
Takanishi K, Yagi T, Umezu M
Proceedings of the 2016 Summer Biomechanics Bioengineering and Biotransport Conference,scientific sessions
218
2016
[Refereed]
Investigation of flow instability with vascular geometry at the bifurcation of middle cerebral arteries from healthy volunteers
Murayoshi T, Yagi T, Tobe Y, Umezu M
Proceedings of the 2016 Summer Biomechanics Bioengineering and Biotransport Conference
215
2016
[Refereed]
Pathological engineering study of human cerebral aneurysms three dimensional accumulation of foam cells versus hemodynamics
Suto K, Yagi T, Tobe Y, Kawamura K, Umezu M
Proceedings of the 2016 summer biomechanics bioengineering and biotransport conference
197
2016
[Refereed]
2A33 Study on an adaptation of hemodynamics before and after cerebrovascular bypass surgery
Induced Pluripotent Stem Cell Differentiation under Constant Shear Stress
N. K. Mohd Zin, K. Sakaguchi, Y. Haraguchi, T. Yagi, K. Masuura, T. Shimizu, M. Umezu
7TH WACBE WORLD CONGRESS ON BIOENGINEERING 2015
52
7
-
10
2015
[Refereed]
View Summary
Mechanotransduction in in-vitro studies has yet to be done extensively using human induced pluripotent (hiPS) cells. These external mechanical factors are important controlling factor for cell differentiation at a cellular level particularly in cardiomyocytes cells. Cells in a living body are being exposed to many kind of stresses; shear stress in particular modulates cellular function in a living body. Similarly, we are trying to understand the link between the shear stress in the bioreactor and the differentiation effects it has on iPS cells. In this study, we investigate the difference of strictly uniform laminar shear stress with a non-uniform laminar flow and its effects on the cell survival rate and differentiation. Additionally, the elimination of biochemical factors were done to satisfy the need of demand for clinically usable cells for the near future use. By eliminating cytokine induced differentiation. In addition, information pertaining to relationship between fluid shear stress, cellular deformations, cell differentiation and cell survival rate could provide a more optimised condition for cultivation specific type of cells within a shorter time period.
Aims: To define the optimal kissing balloon inflation (KBI) after single-stent deployment in a coronary bifurcation model. Methods and results: We deployed stents in main vessels (MV) followed by KBI in various conditions and compared the stent configurations. A) KBI at the operator's discretion vs. under the guidelines of minimal balloon overlapping (MBO). Various stent configurations were observed after the former option, whereas similar maximal dilation points were observed under the MBO guidelines. B) Long balloon overlapping (LBO) vs. MBO with proximal MV dilated by a large balloon. The proximal MV was dilated to an ideal round shape with MBO versus an oval shape with LBO. C) Two-link vs. 3-link stents. Although the 2-link stent was advantageous to open the side branch, it incurred a risk of overdilatation of the proximal struts, whereas the 3-link stent preserved its structure. Computed simulations of coronary flow were analysed in the following left main coronary models: circle with a diameter of 4 and 5 5 mm, ellipse with longitudinal direction and tilt position. They revealed that the overdilated side was exposed to low shear stress regardless of its shape. Conclusions: Optimal KBI can be achieved with MBO and proximal dilatation by an optimally sized balloon.
This research compared the intraoperative appearance, computational fluid dynamic (CFD) analysis, and scanning electron microscope (SEM) observation of endothelial cells (EC) of seven human cerebral aneurysms in an effort to find the relationship between hemodynamic patterns and wallthinning of aneurysms. Aneurysm walls were categorized into blister-like appearance as thinning, similar appearance to the parental artery or white thickened part as thickening, and areas similar to arteriosclerosis as calcifying region. Seven aneurysms were dissected after clipping operation with markings to confirm the orientation of specimens. Specimens were rinsed in PBS, immersed into 2% glutaraldehyde, 1% osmium solution, graded series of ethanol and tertiary-butyl alcohol, and freeze-dried to observe under SEM. For CFD analysis, 3 dimensional vascular models were constructed and meshed using tetra and prism mesh. The inlet boundary condition used an average flow rate of 350 ml/min. The outlet boundary conditions were set to flow rates based on literature data and for regions with unknown flow rates were set to static pressure. Vascular models were analyzed using CFX 13.0 (ANSYS). Aneurysms contained four thinning, six thickening, and four calcifying regions. SEM analysis showed variations of endothelial cell patterns over aneurysms. Missing EC was only found at thinning regions and all thickening and calcifying regions confirmed damaged or normal EC. CFD analysis showed impinging flow at the thinning region. Impingement was defined by the direction of wall shear stress (WSS) vector and rise of pressure at wall. The impinging flow was only found at the thinning region. The WSS magnitude did not confirm any relationship between wall characteristics or EC patterns. These results suggested that the impinging flow may cause wall thinning of aneurysm.
Arterial diseases of sclerosis and aneurysm are known to be related with a local blood flow. There are indeed decades of related studies, recently being with an aid of a computational approach on a patient-specific basis, but those have yet to be translated into clinical medicine. "Simply why?", and "how to achieve it?" Computational blood flow originates from theoretical and computational fluid dynamics. Understanding the underlying knowledge may be beyond the scope of medical professionals. Engineers have to be fully aware of a barrier on an interface with clinical medicine, and manage to translate the evolving technology with a special focus on balancing the efficacy and safety. Visual analytics is to facilitate to overcome an academic gap between engineering and clinical medicine. This paper deals with the recent development of visual analytics of malignant blood flows in cerebral aneurysms for medical professionals.
Trifurcated arch grafts (3-branch grafts) are now being used to repair the thoracic aorta in addition to conventional arch grafts (4-branch grafts). The anatomical shape of the 3-branch graft is different from the original vessel, so it is necessary for clinical application to evaluate blood flow distribution in the graft to assess whether there is adequate blood flow to the target organs. To achieve this, we developed a computational fluid dynamics (CFD) method to evaluate blood flow distribution in the grafts. Aortic blood flow was measured by phase-contrast magnetic resonance imaging (PC-MRI), and flow distribution into the branched vessels was obtained. The MRI image was used to create a patient-specific image model that represents the geometry of the aortic arch. The CFD analysis method was employed to determine a boundary condition of the blood flow analysis in the aorta using a patient-specific image model. We also created simplified models of 4-branch and 3-branch grafts and used our CFD analysis method to compare blood flow distribution among simplified models. It was found that blood flow distribution in the descending aorta was 71.3 % for the 4-branch graft and 67.7 % for the 3-branch graft, indicating that a sum of branching flow in the 3-branch graft was almost the same as the one in the 4-branch graft. Therefore, there is no major concern about implanting a new 3-branch graft. Our CFD analysis method may be applied to estimate blood flow distribution of a newly developed vascular graft prior to its clinical use and provide useful information for safe use of the graft.
JOURNAL OF THE ROYAL SOCIETY INTERFACE
10
(
82
)
20121031
2013.05
[Refereed]
View Summary
This study experimentally investigated the instability of flow impingement in a cerebral aneurysm, which was speculated to promote the degradation of aneurysmal wall. A patient-specific, full-scale and elastic-wall replica of cerebral artery was fabricated from transparent silicone rubber. The geometry of the aneurysm corresponded to that found at 9 days before rupture. The flow in a replica was analysed by quantitative flow visualization (stereoscopic particle image velocimetry) in a three-dimensional, high-resolution and time-resolved manner. The mid-systolic and late-diastolic flows with a Reynolds number of 450 and 230 were compared. The temporal and spatial variations of near-wall velocity at flow impingement delineated its inherent instability at a low Reynolds number. Wall shear stress (WSS) at that site exhibited a combination of temporal fluctuation and spatial divergence. The frequency range of fluctuation was found to exceed significantly that of the heart rate. The high-frequency-fluctuating WSS appeared only during mid-systole and disappeared during late diastole. These results suggested that the flow impingement induced a transition from a laminar regime. This study demonstrated that the hydrodynamic instability of shear layer could not be neglected even at a low Reynolds number. No assumption was found to justify treating the aneurysmal haemodynamics as a fully viscous laminar flow.
Experimental insight into modeling of cerebral aneurysm hemodynamics: comparison between Stereo PIV and CFD
Takahashi S, Yagi T, Umezu M
Proceedings of 11th Asian Symposium on Visualization
2011
[Refereed]
Experimental insight into spatial and temporal dynamics of wall shear rate using elastic replicas of human cerebral aneurysms with fluorescent Stereo PIV
Yagi T, Shinke M, Umezu M
Proceedings of 11th Asian Symposium on Visualization
2011
[Refereed]
"Wind tunnel" in vascular hemodynamics: why and how?
Yagi T, Takahashi S, Tobe Y, Umezu M, Takao H, Murayama Y
Proceedings of the FULUCOME 2011
2011
[Refereed]
Wall shear stress measurement on an elastic boundary in hemodynamic modeling of cerebral aneurysm using fluorescent scanning Stereo PIV
Yagi T, Takahashi S, Umezu M
Proceedings of 9th International Symposium on Particle Image Velocimetry
2011
[Refereed]
Two Stenting at Coronary Artery Bifurcation Yields Slow-Flow Region at Carina: In vitro Pulsatile Flow Investigation Using Elastic 3-Dimensional Stenotic Bifurcated Artery Replica
Single-cell real-time imaging of flow-induced hemolysis using high-speed microfluidic technology
T. Yagi, S. Wakasa, N. Tokunaga, Y. Akimoto, M. Umezu
WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, VOL 25, PT 4: IMAGE PROCESSING, BIOSIGNAL PROCESSING, MODELLING AND SIMULATION, BIOMECHANICS
25
(
4
)
2337
-
2340
2010
[Refereed]
View Summary
Understanding the mechanism of flow-induced blood cell damage, such as hemolysis and platelet activation, plays an important role for arterial diseases and artificial organs. This study for the first time demonstrates the visualization of flow-induced hemolysis in a single-cell real-time manner using high-speed microfluidic technology. Impinging microjets with a velocity of 1.5 m/s order at a nozzle exit were made in the Y- and T-shaped microchannel. The curved (r=10 mu m) and flat collision surface were compared. Porcine fresh erythrocytes were suspended in PBS at Ht=0.5%. Results showed that membrane failure was only observed in the Y-junction. These erythrocytes were initially elongated at the far region, and then longitudinally compressed in the near wall region due to the sharp adverse pressure gradient, whereas those in the T-junction released the membrane tension as the pressure difference per erythrocyte diminished. In the simulation of energy balance, it was found that the dominant force for the longitudinal compression was the pressure difference per erythrocyte. Such erythrocytes showed the sudden drop of elastic modulus, suggesting that the elongated spectrin network of erythrocyte was fragile for the compressive force and immediately broken by the impact force.
High-speed microfluidic study of colliding human erythrocytes at a single-cell real-time scale
Yagi T, Akimoto Y, Umezu M
Proceedings of 6th World Congress on Biomechanics
2010
[Refereed]
3D near-wall flow mapping by fluorescent Stereo-PIV in an elastic replica of human cerebral aneurysm
Yagi T, Sato A, Umezu M
Proceedings of International Symposium on Flow Visualization 2010
2010
[Refereed]
Biomedical Engineering Analysis of the Rupture Risk of Cerebral Aneurysms: Flow Comparison of Three Small Pre-ruptured Versus Six Large Unruptured Cases
A. Kamoda, T. Yagi, A. Sato, Y. Qian, K. Iwasaki, M. Umezu, T. Akutsu, H. Takao, Y. Murayama
13TH INTERNATIONAL CONFERENCE ON BIOMEDICAL ENGINEERING, VOLS 1-3
23
(
1-3
)
1600
-
+
2009
[Refereed]
View Summary
A relationship between blood flows in cerebral aneurysms and their rupture remains obscure. In clinical practice, the size of aneurysms is one of the important factors for determining a strategy of treatment, but in our database three small aneurysms became ruptured during follow-up. Here, we aim to study their pre-ruptured hemodynamics, and differentiate them with those of six large unruptured aneurysms. All the aneurysms occurred in internal carotid artery, and their mean sizes were 6 and 10.8 mm for pre-ruptured and unruptured cases, respectively. We reproduced their replica as a patient-specific elastic model using clinical images obtained by digital subtraction angiography and a series of rapid proto-typing techniques. Flows were reproduced in vitro using a cerebral flow simulator, and visualized by Time-resolved Particle Image Velocimetry. All pre-ruptured cases showed the collision of an incoming flow at a distal neck, and formed a prominent jet stream directing towards the aneurismal head. In contrast, none of unruptured aneurysms had such a marked impingement, and their flows were most likely characterized by swirling patterns. All unruptured cases occurred in a twisted vessel, or carotid siphon, whereas pre-ruptured ones were located downstream whose geometries consisted of a simple curvature. These findings suggest that internal carotid artery has a regional dependency of the risk of aneurismal rupture. Furthermore, the presence of jet streams for small-sized aneurysms may be a substantial indicator of the rupture and immediate treatments.
Microscale Visualization of Erythrocyte Deformation by Colliding with a Rigid Surface Using a High-Speed Impinging Jet
S. Wakasa, T. Yagi, Y. Akimoto, N. Tokunaga, K. Iwasaki, M. Umezu
13TH INTERNATIONAL CONFERENCE ON BIOMEDICAL ENGINEERING, VOLS 1-3
23
(
1-3
)
1422
-
+
2009
[Refereed]
View Summary
Erythrocyte deformation by colliding with a rigid surface using a high-speed impinging jet was studied with microfluidic techniques. We aim to investigate the relevance of colliding erythrocytes with hemolysis. A micro-channel chip was made of polydimenthyl-siloxane (PDMS), which comprised a T- and V-shaped junction with a micro-nozzle and diffuser in order to attain a high-speed microflow with a jet velocity of m/s scale. A high-speed camera with a microscope imaged colliding erythrocytes by shadow imaging. Porcine erythrocyte with a hematocrit of 0.5% in phosphate buffer saline was utilized. At the Y-junction, erythrocytes showed buckling due to an impulsive, longitudinal, compressive deformation. Such anomalous phenomena were not detected at the T-junction, where erythrocytes underwent sequential compressions as approaching the colliding surface. Erythrocyte after buckling showed a hazy membrane while being released from the colliding surface, suggesting the ejection of hemoglobin out of the pore on a membrane. Flow-induced hemolysis has been considered as a model of viscous shear stress and exposure time. From our data, however, it was suggested that hemolysis due to a high-speed impinging flow characterized by mechanical heart valve flows may arise as an impulsive failure of erythrocyte membrane upon collision.
New challenge for studying flow-induced blood damage: macroscale modeling and microscale verification
T. Yagi, S. Wakasa, N. Tokunaga, Y. Akimoto, T. Akutsu, K. Iwasaki, M. Umezu
13TH INTERNATIONAL CONFERENCE ON BIOMEDICAL ENGINEERING, VOLS 1-3
23
(
1-3
)
1430
-
+
2009
[Refereed]
View Summary
Prosthetic heart valves often induce blood cell trauma, but its mechanism is not clearly understood due to the complexity of dynamical flows. We herein propose a new challenge, termed macroscale modeling and microscale verification. This report is the former, and here we aim to clarify the physical interpretation of Reynolds stress for flowing cells. One polymer and two mechanical valves are compared, and the Reynolds stress is visualized using a novel analytical technique including time-resolved particle image velocimetry and continuous wavelet transform. The method enables to analyze the dynamics of Reynolds stress in a spatial and temporal domain. As a result, it is found that the Reynolds stress should be considered as an indicator of impinging flows for circulating cells. Such flows may impulsively apply a colliding force on a membrane of flowing cells. As microscale verification based on this new hypothesis, we are currently investigating such collision phenomena of flowing cells using high-speed microfluidic techniques.
Stereoscopic PIV measurements on 3D swirling convergent flows inside a Spiral Vortex ventricular assist device
Yagi T, Yang W, Umezu M
Proceedings PIV’05, 6th International Symposium on Particle Image Velocimetry
2005
[Refereed]
An investigation of instantaneous high-frequency turbulent stress in the vicinity of artificial heart valves using wavelet transform analysis of Dynamic PIV measurements
Yagi T, Ishikawa D, Sudo H, Akutsu T, Yang W, Iwasaki K, Umezu M
Proceedings of the IFMBE, The 12th ICBME
12
2005
[Refereed]
An experimental investigation of three-dimensional pulsatile flow structures within the Spiral Vortex Ventricular Assist Device using Stereoscopic PIV
Yagi T, Yang W, Ishikawa D, Sudo H, Iwasaki K, Umezu M
Proceedings of the IFMBE, The 12th ICBME
12
2005
[Refereed]
2009
WC on Med Phy & BME
Single-cell real-time imaging of flow-induced hemolysis using high-speed microfluidic technology
Winner:
Yagi T, Umezu M
YSA
2006
ISFV
Real-time planar spectral analysis of instantaneous high-frequency stress on blood cells downstream of an artificial heart valve,
Winner:
Yagi T, W. Yang, M. Umezu
Outstanding Paper Award
2005
ICBME
An experimental investigation of three dimensional pulsatile flow structures within the spiral vortex ventricular assist device using Stereoscopic PIV
Three-dimensional volume characterization of swirling flow with fluid-structure coupling in a spiral vortex pulsatile blood pump
Yagi T, Wakasa S, Yang W, Iwasaki K, Umezu M
45th JSAO&IFAO Joint Congress
Presentation date:
2007
The mechanism of turbulence: new finding of impulsively-generated compressive mechanical stress on blood cells flowing through artificial heart valves,