Blood Flow In Aneurysm Research Articles

Impacts of the aneurysm deformation induced by stent on hemodynamic of blood flow in saccular internal carotid artery aneurysms

Impacts of the aneurysm deformation induced by stent on hemodynamic of blood flow in saccular internal carotid artery aneurysms

Utilizing indocyanine green video angiography to bridge intracranial aneurysm treatment gaps in low- and middle-income countries: a mini-review.

Intracranial aneurysms, affecting 2%-5% of the population, pose a significant challenge to neurosurgeons due to their potential to cause subarachnoid haemorrhage and high mortality rates. Intraoperative angiography is necessary for effective surgical planning and indocyanine green video angiography (ICG-VA) has emerged as a useful tool for real-time visualization of aneurysmal blood flow, aiding in better planning for potential blood flow and detection of aneurysm remnants. This mini narrative review explores the application of ICG-VA in intracranial aneurysm surgery. Compared with conventional dye-based angiography, ICG-VA is safer, more effective and more cost-effective. It can assess haemodynamic parameters, cerebral flow during temporary artery occlusion, completeness of clipping and patency of branch vessels. However, implementing ICG-VA in low- and middle-income countries presents challenges such as financial constraints, limited access to training and expertise, patient selection and consent issues. Addressing these obstacles requires capacity-building, training programmes for neurosurgeons and multidisciplinary teams, technology transfer, equipment donations, public-private partnerships, continued research and development, reducing conventional dye usage, reducing ICG wastage, exploring mechanisms to reuse ICG dyes and advocating for increased government funding and healthcare budgets.

Analysis of the Risk of Basilar Aneurysm Rupture Based on CTA Morphological Parameters

Objective: To investigate morphological risk factors of basilar aneurysm rupture based on computer tomography angiography (CTA) parameters. Materials and methods: The clinical and CTA data of 43 patients with basilar aneurysm admitted to Shaanxi Provincial People’s Hospital from January 2015 to July 2023 were analyzed. The patients were divided into “ruptured group” and “unruptured group,” and the morphological parameters of aneurysms were measured. The general data and morphological parameters between the two groups were statistically analyzed. Logistic regression was used to analyzed statistically significant parameters, and the receiver operating characteristic curve was drawn to evaluate its diagnostic effectiveness. Results: Irregular aneurysms were more likely to rupture than regular aneurysms (x² = 13.971, P < 0.05). The maximum diameter (4.92 [3.37–6.94] mm), length-width ratio (1.31 [1.14–1.55]), height (4.08 [2.71–5.34] mm), aspect ratio (0.99 [0.84–1.45]), and inflow angle (133.63 ± 11.21°) of aneurysms in the ruptured group were larger than the unruptured group, and the differences were statistically significant (P < 0.05). Binary logistic regression showedthat aneurysm shape (OR = 39.347, P = 0.021), length-width ratio (OR = 313.062, P = 0.033), and inflow angle (OR = 1.156, P = 0.004) were independent risk factors for rupture. The area under the curve were 0.809, 0.842. and 0.894, respectively. Conclusion: Aneurysm shape, aspect ratio, and blood flow incidence angle are independent risk factors for basilar aneurysm rupture, which means that they can be used to predict the risk of rupture to a certain extent.

Spectral domain graph convolutional deep neural network for predicting unsteady and nonlinear flows

Mode decomposition methods, such as proper orthogonal decomposition and dynamic mode decomposition (DMD), have introduced a novel data-driven approach for flow prediction. These methods aim to identify a collection of modes that capture the essential flow features. Subsequently, the flow field data are projected onto these modes to reconstruct and predict the evolution of the flow field. However, due to their inherent linearity, mode decomposition methods are limited in effectively handling unsteady and nonlinear flow exhibiting significant nonlinearities. In this study, we propose a spectral graph convolutional deep neural network (SGC-DNN). It employs the eigenvectors of the Laplacian matrix as modes to fully utilize the adjacency information within the graph structure to solve flow on an unstructured grid better. Additionally, we employ a DNN (deep neural network) to model the temporal evolution of each mode, thereby enhancing the model's adaptability to nonlinear flow fields. To evaluate the performance of our proposed SGC-DNN, we compare its prediction results with those obtained using DMD and DNN for the flow around a cylinder on unstructured grids at various Reynolds numbers (ranging from 1000 to 500 000). We also compared the predictive results of these three models for flow with complex geometries, such as the Da Vinci pipeline flow and intracranial aneurysm blood flow. The comparative analysis demonstrates that SGC-DNN outperformed the other models, yielding lower L2 relative errors and higher R2 values. These outcomes highlight the superiority of SGC-DNN in accurately predicting unsteady and nonlinear flow characterized by graph structures.

Towards Prediction of Blood Flow in Coiled Aneurysms Before Treatment: A Porous Media Approach.

Modeling blood flow in aneurysms treated with coils could be used to understand the complete embolization of the aneurysm, through thrombus formation that fills the entire sac. Modeling of the endovascular coil mass as a porous medium is a technique that allows for study of aneurysm hemodynamics, efficiently for patient-specific treatment outcome predictions. Models in the literature use mean porosity of coils in the aneurysmal volume, proving inadequate for outcome prediction. However, models that consider heterogeneous porosity distribution have shown more accurate hemodynamics. We recently published the porous crown model, considering the heterogeneous coil mass distribution, validated on two patients. This study aims (i) to validate the porous crown model for a larger cohort (eight patients), and (ii) to propose a porous medium model translatable to clinical practice in treatment planning. We analyzed the porosity distribution of the endovascular coils deployed inside the cerebral aneurysm phantoms of eight patients using 3D x-ray synchrotron images. The permeability and inertial factor of the porous crown model are calculated using previously published methodology. We propose a new "bilinear" porous model, that uses the same hypothesis, but the permeability and inertial factor can be defined from just basic information available in the neuro-suite, i.e., the aneurysmal sac volume and the coil volume fraction targeted by the neurosurgeon. These two models are compared to the coil-resolved simulations, considered as the gold standard. The results show that both the porous crown model and the bilinear model produce similarly accurate hemodynamics in the aneurysm. The error in the standard (mean porosity) porous model is 66%, whereas the error of the bilinear model is 26%, compared to the coil-resolved. The bilinear model is promising as a means of treatment outcome prediction at time of intervention.

Extrahepatic portal vein aneurysm in which the acute thrombogenic process triggered by trauma confirmed by abdominal ultrasonography: a case report.

Extrahepatic portal vein aneurysm (PVA) is a rare condition in which the extrahepatic portal vein is partially dilated into a sac-like or spindle-like shape. Usually, patients are followed, but surgery is considered in cases of rupture, thrombus, or enlargement. We report a case of thrombus formation in an extrahepatic portal vein aneurysm following trauma that resulted in regression of the aneurysm and extrahepatic portal vein occlusion. Immediately after the trauma, ultrasonography showed moderately hyperechoic structures and comet signs along the vessel wall of the aneurysm and turbulent blood flow in the aneurysm, like in a whirlpool. There were floating point-like echogenic features, which were presumed to be microthrombi. In other words, the trauma might have triggered Virchow's triad: changes in the vessel wall, changes in blood properties, and blood stagnation. This is a valuable case in which ultrasonography imaging revealed interesting changes during the thrombus formation process inside an extrahepatic portal vein aneurysm. The aneurysm's size was reduced by thrombus-induced organization, but the main trunk of the portal vein became deficient in blood flow, resulting in extrahepatic portal vein occlusion. This case is suggestive of the mechanism of extrahepatic portal vein occlusion.

Evaluation of Intra-Aneurysmal Residual Blood Flow with the iMSDE T1-Black Blood Imaging after Flow Diverter Treatment.

We aimed to evaluate the efficacy of the "improved motion-sensitized driven-equilibrium (iMSDE)"-prepared T1-weighted black blood (T1-BB) MRI for monitoring treatment effect with a flow diverter (FD) for cerebral aneurysms. Following the exclusion of concomitant coiling and retreatment cases from 60 consecutive cases of cerebral aneurysms treated with FDs at our institution, 32 with imaging data were included in the analysis. Detectability of residual blood flow within the aneurysms was validated as follows: 1) comparison of MRI sequences (iMSDE-prepared T1-BB images, T1-weighted images [ T1WI], and time-of-flight [ TOF]-MRA) in cases of incompletely occluded aneurysms and 2) comparison of angiography and MRI sequences in the same period. 1) The probability of diagnosing intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p <0.001). 2) The diagnostic accuracy of residual aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB than that with T1WI (p = 0.032). Furthermore, in cases of incomplete occlusion, the probability of detecting intra-aneurysmal blood flow was significantly higher with iMSDE-prepared T1-BB (iMSDE-prepared T1-BB vs. T1WI, p <0.001; iMSDE-prepared T1-BB vs. TOF-MRA, p = 0.023). Our results demonstrated that iMSDE-prepared T1-BB could help distinguish between blood flow and thrombus within the aneurysms after FD treatment, especially in the early stages of FD treatment.

Fluid-structure interaction model of blood flow in abdominal aortic aneurysms with thermic treatment

Hyperthermia is one of the non-invasive therapy of an Abdominal Aortic Aneurysm (AAA), which is achieved by applying a heat source upon the AAA without surgical operation. This research paper considers laminar flow and heat transfer in a heated abdominal aortic aneurysm using an isothermal boundary condition. Heat is added to explicate the thermal treatment of a diseased artery. The blood is assumed as a non-Newtonian fluid based on the shear-thinning Carreau model. Two unequal aneurysms are assumed in the lower wall to simulate bulges or a disordered artery. Flexible wall segments are assumed in the upper wall and opposing to each aneurysm. The transient momentum and energy equations are solved based on the fluid–structure interaction (FSI) using the Arbitrary-Lagrangian–Eulerian (ALE) method. It is found that the shear stress is much higher for a higher index of the power-law fluid governing the blood viscosity and hence, it is strictly recommended to reduce the viscous nature of the blood in diseased vessels. It is found also that the thermal energy can be greatly transported across the blood at a higher Reynolds number, this means that the hyperthermia therapy becomes effective when blood flows violently through the aortic.

Numerical analysis of blood flow in abdominal aortic aneurysm using finite volume method

There is a deadly cardiovascular disease that can cause swelling of the Abdominal Aorta. This disease is known as Abdominal Aortic Aneurysm (AAA). AAA is believed to be a degenerative process caused by genetic factors, gender, body weight, and age. Changes in collagen and elastin in the aortic wall are the cause of the degeneration process. Therefore, it will cause dilatation of the aortic wall. Swelling of the aortic blood vessels will affect the blood flow velocity in the aortic blood vessels. This research aims to analyze the velocity of blood flow in the Abdominal Aortic Aneurysm based on swelling diameter, proximal neck length, and aneurysm channel length using Computational Fluids Dynamics (CFD). The blood flow velocity was modeled using mathematical language based on mass continuity equations and momentum equations. Then the finite volume method was one method to solve the mathematical model. MATLAB and ANSYS FLUENT software were used to simulate the velocity of blood flow analysis. The results of the research were shown that the larger the diameter and swelling channel length, the smaller the velocity of blood flow produced. Then, the greater the length of the proximal neck, the faster the resulting blood flow will be.

Lattice Boltzmann model for simulation of flow in intracranial aneurysms considering non-Newtonian effects

We propose a robust modified central Hermite polynomial-based multiple relaxation time lattice Boltzmann model with independent control over relaxation of acoustic modes for non-Newtonian fluids, more specifically in the context of blood flow in intracranial aneurysms. The use of the robust collision operator along with the implicit computation of the non-linear stress allows for a very wide operation domain in terms of time step and grid-size. The solver is first validated via well-documented configurations such as the 2D Poiseuille–Hagen and lid-driven cavity flows with a power-law fluid. The results clearly show second-order convergence of the scheme. The model is then used to simulate pulsating flow in an ideal aneurysm geometry with four different viscosity laws, namely, Newtonian, power-law, Carreau–Yasuda, and Cross. The results show that the assumption of high shear rates does not necessarily hold within the aneurysm sac. Finally, the solver is used to simulate pulsating blood flow in a patient-specific configuration.

Insufficient Closing Forces of Yasargil Titanium Clips in Two Small Aneurysms Detected with Intraoperative Indocyanine Green Videoangiography.

Aneurysm clips must have adequate closing forces because residual blood flow in clipped aneurysms may result in aneurysm recurrence. Such flow can be intraoperatively detected by visual inspection, microvascular Doppler sonography, indocyanine green videoangiography (ICG-V), angiography, and puncture. We present two patients with ruptured very small middle cerebral artery aneurysms (3 and 2.9 mm). The necks of both aneurysms were microsurgically clipped with Yasargil aneurysm clips without any complications. In both aneurysms, visual inspection suggested complete occlusion, but ICG-V showed persistent residual blood flow between the middle parts of the clip blades.The first patient was treated with a 5.4-mm FT744T clip (closing force of 1.47 N). After the ICG-V finding, a second 3.9-mm FT714T clip (closing force of 1.08 N) was placed on the tips of the already implanted clip to increase the closing forces. Subsequent ICG-V did not show any further residual blood flow. In the second patient, the aneurysm was clipped with an 8.0-mm FE764K clip (closing force of 1.77 N). Intraoperative ICG-V showed persistent residual blood flow within the aneurysmal dome despite complete closure of the clip. The clip was repositioned closer to the parent vessel. Consecutive ICG-V did not show any residual blood flow. Visually undetected incomplete aneurysm occlusion can be revealed with ICG-V. In very small aneurysms, standard closing forces of clips may not be sufficient and complete closure of the clip branches should be intraoperatively validated with ICG-V.

Effect of Proximal Parent Artery Stenosis on the Outcomes of Posterior Communicating Artery Aneurysms: A Preliminary Study Based on Case-Specific Hemodynamic Analysis

The objective of the study was to evaluate the effect of proximal parent artery stenosis on the hemodynamics of aneurysms in the internal carotid artery-posterior communicating artery (ICA-Pcom). A retrospective study of 74 patients with aneurysms in the ICA-Pcom who underwent treatment at the Department of Neurosurgery of Changhai Hospital was conducted between January and June 2018. Patients with proximal parent artery stenosis were included. Case-specific three-dimensional images were reconstructed, and software-based simulations of different stenosis morphologies were performed, focusing on stenosis severity and the distance from the aneurysm to the stenosis. The wall shear stress (WSS) of the aneurysms and blood flow velocity of the aneurysm neck plane were calculated. We performed simulations to evaluate the outcomes of postballoon angioplasty by considering a virtual operation group. To further assess whether WSS after balloon angioplasty increases the risk of aneurysm rupture, a control group of ruptured ICA-Pcom aneurysms without parent artery stenosis was matched with the virtual operation group based on sex, age, history of hypertension, and aneurysm size. Thereafter, the normalized WSS of the 2 groups was calculated. Eight patients with parent artery stenosis were included (2 men and 6 women; average age: 64±15years). The patients were divided into eccentric and concentric stenosis groups according to the stenotic morphologies, with 4 patients in each group. In both groups, the average WSS of the aneurysm and average blood flow velocity at the neck plane increased with the severity of parent artery stenosis, whereas the WSS did not correlate with distance. In the concentric stenosis group, the average blood flow velocity generally decreased as the distance between stenosis and aneurysm increased; however, no such trend was observed in the eccentric stenosis group. The normalized WSS of aneurysms after virtual balloon angioplasty was higher than that of the ruptured aneurysms (0.599 [0.548, 0.800] vs. 0.367 [0.324, 0.407]; P=0.007). Intensified severity of proximal stenosis increases the blood flow velocity and aneurysmal WSS, which may lead to the progression of ICA-Pcom aneurysms. Treatment of the stenosis can reduce the WSS of aneurysms; however, its effect on the prognosis of ICA-Pcom aneurysms requires more concrete evidence.

Targeting Platelet Activation in Abdominal Aortic Aneurysm: Current Knowledge and Perspectives.

Abdominal aortic aneurysm (AAA) is a potentially fatal vascular disease that involves complex multifactorial hemodynamic, thrombotic, inflammatory, and aortic wall remodeling processes. However, its mechanisms are incompletely understood. It has become increasingly clear that platelets are involved in pathological processes of vascular diseases beyond their role in hemostasis and thrombosis. Platelet activation with membrane receptors and secreted mediators promotes thrombus formation and the accumulation of inflammatory cells, which may play an important role in the development of AAA by destroying the structural integrity and stability of the vessel wall. Turbulent blood flow in aortic aneurysms promotes platelet activation and aggregation. Platelet count and heterogeneity are important predictive, diagnostic, and prognostic indicators of AAA. We summarize the relationship between platelet activation and AAA development and propose future research directions and possible clinical applications.

Hemodynamic Analysis of Pipeline Embolization Device Stent for Treatment of Giant Intracranial Aneurysm under Unsupervised Learning Algorithm.

To treat large intracranial aneurysms, pipeline embolization device (PED) stent with unsupervised learning algorithms was utilized. Unsupervised learning model algorithm was used to screen aneurysm health big data, find aneurysm blood flow and PED stent positioning characteristic parameters, and guide PED stent treatment of intracranial aneurysms. The research objects were 100 patients with intracranial large aneurysm admitted to X Hospital of X Province from June 2020 to June 2021, who were enrolled into two groups. One group used the prototype transfer generative adversarial network (PTGAN) model to measure mean blood flow and mean vascular pressure and guide the placement of PED stents (PTGAN group). The other group did not use the model to place PED (control group). The PTGAN model can learn feature information from horizontal and vertical directions, with smooth edges and prominent features, which can effectively extract the main morphological and texture features of aneurysms. Compared with the convolutional neural network (CNN) model, the accuracy of the PTGAN model increased by 8.449% (87.452%–79.003%), and the precision increased by 8.347% (91.23%–82.883%). The recall rate increased by 7.011% (87.231%–80.22%), and the F1 score increased by 8.09% (89.73%–81.64%). After the adoption of the PTGAN model, the average blood flow inside the aneurysm body was 0.22 (m/s). After the adoption of the CNN model, the average blood flow inside the aneurysm body was 0.21 (m/s), and the difference was 0.01 (m/s), which was considerable (p < 0.05). Through this research, it was found that the PTGAN model was better than the CNN model in terms of accuracy, precision, recall, and F1 score values. The PTGAN model was better than the CNN model in detecting the average blood flow rate and average blood pressure after treatment, and the blood flowed smoothly. Postoperative complications and postoperative relief were also better than those of the control group. In summary, based on the unsupervised learning algorithm, the PED stent had a good adoption effect in the treatment of intracranial aneurysms and was suitable for subsequent treatment.

Analytical and Computational Investigation of Blood Flow in Generic Aortic Aneurysm: A Closed Conduit Approach

Analytical and Computational Investigation of Blood Flow in Generic Aortic Aneurysm: A Closed Conduit Approach

Blood flow in abdominal aortic aneurysms indicates severity and threat

Modeling underlying flow in abdominal aortic aneurysms will aid monitoring, severity assessment and patient care.

Intra-aneurysmal thrombosis and turbulent flow on MRI of large and giant internal carotid artery aneurysms

ObjectiveLarge and giant intracranial aneurysms are vascular pathologies associated with high morbidity and mortality. The purpose of this study was to assess large and giant internal carotid artery (ICA) aneurysms and their intra-aneurysm thrombosis and turbulent flow on magnetic resonance (MR) imaging. MethodsThis study investigated the large and giant ICA aneurysms in 12 patients. MR images, angiograms, and their treatment were retrospectively reviewed. ResultsMR imaging demonstrated high and intermediate signals in addition to the normal flow void. The heterogeneous MR intensities correspond to turbulent flow, laminar flow, or intramural thrombosis. Turbulent flow in 8 cases and intramural thrombosis in 4 cases. Angiography showed turbulent blood flow in saccular and fusiform aneurysms with smooth walls. Intra-aneurysm thrombosis was found in fusiform aneurysms associated with pathology of adjacent ICA wall. A growing saccular aneurysm of the ICA with regular wall involving a turbulent flow was observed. ConclusionThe turbulent flow and thrombosis in large and giant aneurysms can be detected on MR images. Most large and giant aneurysm is not fill with thrombus but turbulent blood flow. Partially thrombosed lesions are caused by pathology vessel wall not turbulent flow. Aneurysm growth can be caused by turbulent blood flow and intra-aneurysm thrombosis.

Sudden circulatory collapse caused by mechanical obstruction of the left main coronary trunk with infective endocarditis vegetation: a case report

BackgroundAcute coronary syndrome (ACS) caused by mechanical obstruction of the coronary artery with a vegetation is extremely rare but associated with high mortality. The optimal management strategy of this condition remains controversial because of its scarcity. We experienced a case of sudden circulatory collapse due to mechanical occlusion of the left main coronary trunk with a vegetation.Case presentationA 68-year-old woman with aortic and mitral valve infective endocarditis suffered sudden dyspnea followed by heart arrest while awaiting surgery. Despite treatment with adequate antibiotic therapy, she had had multiple embolic infarctions and ruptured infectious cerebral aneurysms. We conducted transcatheter arterial embolization of the aneurysm and postponed the cardiac surgery due to residual aneurysmal blood flow. She suffered sudden cardiac arrest, and extracorporeal membrane oxygenation was applied after cardiopulmonary resuscitation. An echocardiogram revealed diffuse severe hypokinesis, and emergency coronary angiography was performed under suspicion of ACS. It revealed obstruction of the left main coronary trunk by a vegetation. Emergent cardiac surgery was performed. A vegetation had occluded the left coronary orifice. Aortic and mitral valve replacement with coronary artery bypass to the left antero-descending branch was performed. Regarding her cardiac function, she still required extracorporeal membrane oxygenation after surgery. She passed away 19 days after surgery due to multiple organ failure.ConclusionsACS caused by mechanical obstruction of the coronary artery with a vegetation is rare but associated with high mortality. When circulatory collapse acutely occurs in patients with aortic valve infective endocarditis, we should suspect acute coronary artery obstruction. Urgent coronary angiography is mandatory to rescue the patient while preparing for emergency surgery.

Simulation of intracranial hemodynamics by an efficient and accurate immersed boundary scheme.

We use computational fluid dynamics (CFD) to simulate blood flow in intracranial aneurysms (IAs). Despite ongoing improvements in the accuracy and efficiency of body-fitted CFD solvers, generation of a high quality mesh appears as the bottleneck of the flow simulation and strongly affects the accuracy of the numerical solution. To overcome this drawback, we use an immersed boundary method. The proposed approach solves the incompressible Navier-Stokes equations on a rectangular (box) domain discretized using uniform Cartesian grid using the finite element method. The immersed object is represented by a set of points (Lagrangian points) located on the surface of the object. Grid local refinement is applied using an automated algorithm. We verify and validate the proposed method by comparing our numerical findings with published experimental results and analytical solutions. We demonstrate the applicability of the proposed scheme on patient-specific blood flow simulations in IAs.

3D Modeling of Blood Flow in Simulated Abdominal Aortic Aneurysm.

Besides biological factors, abdominal aortic aneurysm rupture is also caused by mechanical parameters, which are constantly affecting the wall's tissue due to their abnormal values. The ability to evaluate these parameters could vastly improve the clinical treatment of patients with abdominal aortic aneurysms. The objective of this study was to develop and demonstrate a methodology to analyze the fluid dynamics that cause the wall stress distribution in abdominal aortic aneurysms, using accurate 3D geometry and a realistic, nonlinear, elastic biomechanical model using a computer-aided software. The geometry of the abdominal aortic aneurysm; was constructed on a 3D scale using computer-aided software SolidWorks (Dassault Systems SolidWorksCorp., Waltham MA). Due to the complex nature of the abdominal aortic aneurysm geometry, the physiological forces and constraints acting on the abdominal aortic aneurysm wall were measured by using a simulation setup using boundary conditions and initial conditions for different studies such as finite element analysis or computational fluid dynamics. The flow pattern showed an increase velocity at the angular neck, followed by a stagnated flow inside the aneurysm sack. Furthermore, the wall shear stress analysis showed to focalized points of higher stress, the top and bottom of the aneurysm sack, where the flow collides against the wall. An increase of the viscosity showed no significant velocity changed but results in a slight increase in overall pressure and wall shear stress. Conducting computational fluid dynamics modeling of the abdominal aortic aneurysm using computer-aided software SolidWorks (Dassault Systems SolidWorksCorp., Waltham MA) proves to be an insightful approach for the clinical setting. The careful consideration of the biomechanics of the abdominal aortic aneurysm may lead to an improved, case-specific prediction of the abdominal aortic aneurysm rupture potential, which could significantly improve the clinical management of these patients.