scholarly journals Thrombin–Fibrinogen In Vitro Flow Model of Thrombus Growth in Cerebral Aneurysms

TH Open ◽  
2021 ◽  
Vol 05 (02) ◽  
pp. e155-e162
Author(s):  
Malebogo N. Ngoepe ◽  
Etheresia Pretorius ◽  
Ilunga J. Tshimanga ◽  
Zahra Shaikh ◽  
Yiannis Ventikos ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Computational Models ◽  
Flow Model ◽  
Three Dimensional ◽  
Significant Risk ◽  
Cerebral Aneurysms ◽  
Parent Vessel ◽  
Risk Of Rupture ◽  
Aneurysm Thrombosis

AbstractCerebral aneurysms are balloon-like structures that develop on weakened areas of cerebral artery walls, with a significant risk of rupture. Thrombi formation is closely associated with cerebral aneurysms and has been observed both before and after intervention, leading to a wide variability of outcomes in patients with the condition. The attempt to manage the outcomes has led to the development of various computational models of cerebral aneurysm thrombosis. In the current study, we developed a simplified thrombin–fibrinogen flow system, based on commercially available purified human-derived plasma proteins, which enables thrombus growth and tracking in an idealized cerebral aneurysm geometry. A three-dimensional printed geometry of an idealized cerebral aneurysm and parent vessel configuration was developed. An unexpected outcome was that this phantom-based flow model allowed us to track clot growth over a period of time, by using optical imaging to record the progression of the growing clot into the flow field. Image processing techniques were subsequently used to extract important quantitative metrics from the imaging dataset, such as end point intracranial thrombus volume. The model clearly demonstrates that clot formation, in cerebral aneurysms, is a complex interplay between mechanics and biochemistry. This system is beneficial for verifying computational models of cerebral aneurysm thrombosis, particularly those focusing on initial angiographic occlusion outcomes, and will also assist manufacturers in optimizing interventional device designs.

scholarly journals Effect of Pulsatility on the Transport of Thrombin in an Idealized Cerebral Aneurysm Geometry

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 133
Author(s):  
Struan Hume ◽  
Jean-Marc Ilunga Tshimanga ◽  
Patrick Geoghegan ◽  
Arnaud G. Malan ◽  
Wei Hua Ho ◽  
...  
Keyword(s):  
Computational Model ◽  
Steady Flow ◽  
Cerebral Aneurysm ◽  
Computational Models ◽  
Cerebral Aneurysms ◽  
Scalar Function ◽  
Aneurysm Wall ◽  
Aneurysm Thrombosis ◽  
Using Data

Computational models of cerebral aneurysm thrombosis are designed for use in research and clinical applications. A steady flow assumption is applied in many of these models. To explore the accuracy of this assumption a pulsatile-flow thrombin-transport computational fluid dynamics (CFD) model, which uses a symmetrical idealized aneurysm geometry, was developed. First, a steady-flow computational model was developed and validated using data from an in vitro experiment, based on particle image velocimetry (PIV). The experimental data revealed an asymmetric flow pattern in the aneurysm. The validated computational model was subsequently altered to incorporate pulsatility, by applying a data-derived flow function at the inlet boundary. For both the steady and pulsatile computational models, a scalar function simulating thrombin generation was applied at the aneurysm wall. To determine the influence of pulsatility on thrombin transport, the outputs of the steady model were compared to the outputs of the pulsatile model. The comparison revealed that in the pulsatile case, an average of 10.2% less thrombin accumulates within the aneurysm than the steady case for any given time, due to periodic losses of a significant amount of thrombin-concentrated blood from the aneurysm into the parent vessel’s bloodstream. These findings demonstrate that pulsatility may change clotting outcomes in cerebral aneurysms.

Abstract 2731: CFD Reveals Hemodynamic Differences Between Unruptured And Ruptured Intracranial Aneurysms During Observation

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Hiroyuki Takao ◽  
Yuichi Murayama ◽  
Toshihiro Ishibashi ◽  
Ichiro Yuki ◽  
Shinobu Otsuka ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Significant Risk ◽  
Cerebral Aneurysms ◽  
Aneurysm Rupture ◽  
Medium Size ◽  
Hemodynamic Parameters ◽  
Natural Risk ◽  
Risk Of Rupture ◽  
Significant Difference

Background and Purpose: Although various studies have been performed, the mechanism leading to the rupture of cerebral aneurysms has not yet been elucidated. Accurate assessment of cerebral aneurysm rupture risk is important because current treatments carry a small but significant risk that can exceed the small natural risk of rupture. Various hemodynamic parameters have been proposed for estimating the risk of rupture of cerebral aneurysms, with limited success. We evaluated several hemodynamic parameters to predict rupture in a dataset of initially unruptured aneurysms in which some aneurysms ruptured during follow-up observation. Methods: Geometry of the aneurysm and blood vessels was extracted from CTA images and analyzed using a mathematical formula for fluid flow under pulsatile blood flow conditions. Fifty side-wall internal carotid posterior communicating artery (ICA-pcom) aneurysms and fifty middle cerebral artery (MCA) bifurcation aneurysms of medium size were investigated for Energy loss (EL), Pressure Loss Coefficient (PLC), wall-shear-stress (WSS) and oscillatory shear index (OSI). During a follow-up observation period, 6 ICA-pcom and 7 MCA aneurysms ruptured (44 and 43 remained unruptured, respectively, with the same location and a similar size as the ruptured cases). Results: A significant difference in the minimum WSS between aneurysms that ruptured and those that remained unruptured was noted only in ICA aneurysms (P<0.001). EL showed higher tendency in ruptured aneurysms but statistically not significant. For PLC, a significant difference was noted in both ICA (P<0.001) and MCA (P<0.001) aneurysms. All other parameters did not show significant differences between the two groups. Conclusion: A significant difference was noted in WSSMIN only in ICA aneurysms. For PLC, a significant difference was noted in both ICA and MCA aneurysms, suggesting that PLC may be one, out of possibly other useful parameters to predict cerebral aneurysm rupture.

500 An in vitro steady flow model of mitral regurgitation by three-dimensional Doppler

1999 ◽  
Vol 1 ◽  
pp. S86-S86
Author(s):  
R DESIMONE ◽  
G GLOMBITZA ◽  
C VAHL ◽  
H MEINZER ◽  
S HAGL
Keyword(s):  
Mitral Regurgitation ◽  
Steady Flow ◽  
Flow Model ◽  
Three Dimensional

scholarly journals Rescue Therapy for Procedural Complications Associated With Deployment of Flow-Diverting Devices in Cerebral Aneurysms

2018 ◽  
Vol 15 (6) ◽  
pp. 624-633 ◽  
Author(s):  
Fawaz Al-Mufti ◽  
Krishna Amuluru ◽  
Eric R Cohen ◽  
Vikas Patel ◽  
Mohammad El-Ghanem ◽  
...  
Keyword(s):  
Rescue Therapy ◽  
Significant Risk ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Side Branch ◽  
Parent Vessel ◽  
Vessel Injury ◽  
Procedural Complications ◽  
Background Material ◽  
Device Deployment

Abstract Flow diverting devices (FDDs) have revolutionized the treatment of morphologically complex intracranial aneurysms such as wide-necked, giant, or fusiform aneurysms. Although FDDs are extremely effective, they carry a small yet significant risk of intraprocedural complications. As the implementation of these devices increases, the ability to predict and rapidly treat complications, especially those that are iatrogenic or intraprocedural in nature, is becoming increasingly more necessary. Our objective in this paper is to provide a descriptive summary of the various types of intraprocedural complications that may occur during FDDs deployment and how they may best be treated. A systematic and qualitative review of the literature was conducted using electronic databases MEDLINE and Google Scholar. Searches consisted of Boolean operators “AND” and “OR” for the following terms in different combinations: “aneurysm,” “endovascular,” “flow diverter,” “intracranial,” and “pipeline.” A total of 94 papers were included in our analysis; approximately 87 of these papers dealt with periprocedural endovascular (mainly related to FDDs) complications and their treatment; 7 studies concerned background material. The main categories of periprocedural complications encountered during deployment of FDDs are failure of occlusion, parent vessel injury and/or rupture, spontaneous intraparenchymal hemorrhage, migration or malposition of the FDDs, thromboembolic or ischemic events, and side branch occlusion Periprocedural complications occur mainly due to thromboembolic events or mechanical issues related to device deployment and placement. With increasing use and expanding versatility of FDDs, the understanding of these complications is vital in order to effectively manage such situations in a timely manner.

scholarly journals Prediction of Aerosol Deposition in the Human Respiratory Tract via Computational Models: A Review with Recent Updates

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 137 ◽  
Author(s):  
Vu Khac Hoang Bui ◽  
Ju-Young Moon ◽  
Minhe Chae ◽  
Duckshin Park ◽  
Young-Chul Lee
Keyword(s):  
Respiratory Tract ◽  
Particle Deposition ◽  
Computational Models ◽  
Aerosol Particles ◽  
Three Dimensional ◽  
Aerosol Deposition ◽  
Research Area ◽  
Human Respiratory Tract

The measurement of deposited aerosol particles in the respiratory tract via in vivo and in vitro approaches is difficult due to those approaches’ many limitations. In order to overcome these obstacles, different computational models have been developed to predict the deposition of aerosol particles inside the lung. Recently, some remarkable models have been developed based on conventional semi-empirical models, one-dimensional whole-lung models, three-dimensional computational fluid dynamics models, and artificial neural networks for the prediction of aerosol-particle deposition with a high accuracy relative to experimental data. However, these models still have some disadvantages that should be overcome shortly. In this paper, we take a closer look at the current research trends as well as the future directions of this research area.

Endovascular Treatment of Cerebral Aneurysms

2002 ◽  
Vol 15 (5) ◽  
pp. 537-548 ◽  
Author(s):  
G.B. Bradač ◽  
G. Stura ◽  
M. Bergui
Keyword(s):  
Endovascular Treatment ◽  
Cerebral Aneurysm ◽  
Essential Role ◽  
Cerebral Aneurysms ◽  
Balloon Occlusion ◽  
New Technique ◽  
Endovascular Techniques ◽  
Parent Vessel ◽  
Endovascular Approach

Balloon occlusion of parent vessel and direct coiling are the two endovascular techniques routinely used and commonly accepted as alternatives to surgery for treatment of the cerebral aneurysm in many patients. Based on our experience and what is reported in the literature, the various aspects concerning techniques, difficulties, risks, are described. In comparison to surgery, the endovascular approach is a relatively new technique, which is still in evolution. To date, there is no objective indication regarding the method to be used in a given case. The experience and attitude of the involved team still play an essential role.

scholarly journals A Better, Faster Road From Biological Data to Human Health: A Systems Biology Approach for Engineered Cell Cultures

2017 ◽  
Author(s):  
Brian T. Hawkins ◽  
Sonia Grego
Keyword(s):  
Systems Biology ◽  
Computational Models ◽  
Three Dimensional ◽  
Toxicity Testing ◽  
Biological Data ◽  
Physiological Relevance ◽  
Toxicity Risk ◽  
Therapeutic Development ◽  
Single Cell Type

Traditionally, the interactions of drugs and toxicants with human tissue have been investigated in a reductionist way—for example, by focusing on specific molecular targets and using single-cell-type cultures before testing compounds in whole organisms. More recently, “systems biology” approaches attempt to enhance the predictive value of in vitro biological data by adopting a comprehensive description of biological systems and using computational tools that are sophisticated enough to handle the complexity of these systems. However, the utility of computational models resulting from these efforts completely relies on the quality of the data used to construct them. Here, we propose that recent advances in the development of bioengineered, three-dimensional, multicellular constructs provide in vitro data of sufficient complexity and physiological relevance to be used in predictive systems biology models of human responses. Such predictive models are essential to maximally leveraging these emerging bioengineering technologies to improve both therapeutic development and toxicity risk assessment. This brief outlines the opportunities presented by emerging technologies and approaches for the acceleration of drug development and toxicity testing, as well as the challenges lying ahead for the field.

scholarly journals Patient-Specific Aortic Phantom With Tunable Compliance

2019 ◽  
Vol 2 (4) ◽  
Author(s):  
Antonio Gallarello ◽  
Andrea Palombi ◽  
Giacomo Annio ◽  
Shervanthi Homer-Vanniasinkam ◽  
Elena De Momi ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Computational Models ◽  
Three Dimensional ◽  
Complex Interventions ◽  
Patient Specific ◽  
Arch Model ◽  
Magnetic Resonance Imaging Mri ◽  
Variable Wall ◽  
Silicone Model

Abstract Validation of computational models using in vitro phantoms is a nontrivial task, especially in the replication of the mechanical properties of the vessel walls, which varies with age and pathophysiological state. In this paper, we present a novel aortic phantom reconstructed from patient-specific data with variable wall compliance that can be tuned without recreating the phantom. The three-dimensional (3D) geometry of an aortic arch was retrieved from a computed tomography angiography scan. A rubber-like silicone phantom was manufactured and connected to a compliance chamber in order to tune its compliance. A lumped resistance was also coupled with the system. The compliance of the aortic arch model was validated using the Young's modulus and characterized further with respect to clinically relevant indicators. The silicone model demonstrates that compliance can be finely tuned with this system under pulsatile flow conditions. The phantom replicated values of compliance in the physiological range. Both, the pressure curves and the asymmetrical behavior of the expansion, are in agreement with the literature. This novel design approach allows obtaining for the first time a phantom with tunable compliance. Vascular phantoms designed and developed with the methodology proposed in this paper have high potential to be used in diverse conditions. Applications include training of physicians, pre-operative trials for complex interventions, testing of medical devices for cardiovascular diseases (CVDs), and comparative Magnetic-resonance-imaging (MRI)-based computational studies.

Computational Analyses of an In-Vitro Aneurysm Model Based on Three-Dimensional Angiography With Comparison to Phase Contrast Magnetic Resonance Imaging and Dye Injection Studies

2010 ◽  
Author(s):  
Stephanie M. George ◽  
Pierre Watson ◽  
John N. Oshinski ◽  
Charles W. Kerber ◽  
Daniel Karolyi ◽  
...  
Keyword(s):  
High Speed ◽  
Phase Contrast ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cerebral Aneurysms ◽  
Computational Fluid Dynamic Simulation ◽  
Poor Correlation ◽  
Aneurysm Model

Computational fluid dynamic simulation (CFD) is a valuable tool that has been used to understand some of the fundamental conditions of cerebrovascular flow. Current methods include anatomic modeling of cerebral aneurysms derived from vascular imaging such as MRA, CTA, and three-dimensional angiography. The input blood flow waveforms can be represented from either mathematical models or physiologic sampling of flow with phase contrast MR techniques or particle image velocimetry (1). While there has been general acceptance of the validity of computational fluid dynamics, some research suggests that there can be poor correlation between CFD flow calculations and directly measured flow (2). Therefore, the purpose of this study is to qualitatively compare flow patterns in a cerebral aneurysm model using data derived from three sources: (i) direct phase contrast MRA measurement in the model; (ii) CFD simulation using computer models created from three dimensional angiography, and (iii) previously published high speed injection dye studies.

The canine tail artery as a model for cerebral aneurysm studies

1989 ◽  
Vol 67 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Teresa Terpin Boyce ◽  
Margot R. Roach
Keyword(s):  
Cross Section ◽  
Flow Model ◽  
Cerebral Aneurysms ◽  
The Body ◽  
Iliac Arteries ◽  
Aorta Aneurysm ◽  
Tail Artery ◽  
India Ink ◽  
Reasonable Model

The occluded canine tail artery, which comes off in the same plane as the aortoiliac junction, has been used as a flow model for cerebral aneurysms. These experiments were designed to determine if it is a realistic distensible model of human intracranial aneurysms. Distensibility studies were done on the aorta, and the iliac and tail arteries of four dogs. From these pressure–volume studies, tension–strain curves, elastances, and collagen slack were obtained. The tail artery is stiffer longitudinally and more distensible circumferentially than the other vessels. The iliac arteries and the aorta are not significantly different. The elastance of elastin and collagen is lower in the tail artery, and the collagen is more wavy circumferentially. Longitudinally, the collagen slack is least for the tail artery, and the elastance of elastin is not different in all three vessels. The number of elastin layers in the iliac and tail arteries seen in cross section is not significantly different, but the aorta is different from both these vessels. In another four dogs the aorta proximal to the trifurcation was cannulated and infused with saline to increase pressure. India ink marks were put on the surface to measure changes in length. Photographs were taken at intervals of 10 mmHg(1 mmHg = 133.3 Pa). This was done with the vessels tethered and untethered in the body and then taken out and studied with the same method in vitro. Arteries tethered in the body expanded circumferentially more than longitudinally. The tail artery becomes less distensible if untethered in the body and therefore acts more like an aneurysm. This makes it a good distensible flow model for aneurysm study. Even though the walls of the tail artery are thick and the geometry is not spherical, it is a reasonable model to study flow in aneurysms.Key words: elasticity, aorta, aneurysm, tethering, canine.

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