Mass transfer and blood flow in a patient-specific three-dimensional Willis circle

2021 ◽  
Vol 126 ◽  
pp. 105369
Author(s):  
Alessio Pignani ◽  
Ivan Di Venuta ◽  
Andrea Boghi ◽  
Fabio Gori
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Three Dimensional ◽  
Patient Specific

Does the DSA reconstruction kernel affect hemodynamic predictions in intracranial aneurysms? An analysis of geometry and blood flow variations

2017 ◽  
Vol 10 (3) ◽  
pp. 290-296 ◽  
Author(s):  
P Berg ◽  
S Saalfeld ◽  
S Voß ◽  
T Redel ◽  
B Preim ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Aneurysms ◽  
Three Dimensional ◽  
Patient Specific ◽  
Parent Artery ◽  
Imaging Data ◽  
Specific Flow ◽  
Aneurysm Neck ◽  
Velocity Magnitude ◽  
Reconstruction Kernel

BackgroundComputational fluid dynamics (CFD) blood flow predictions in intracranial aneurysms promise great potential to reveal patient-specific flow structures. Since the workflow from image acquisition to the final result includes various processing steps, quantifications of the individual introduced potential error sources are required.MethodsThree-dimensional (3D) reconstruction of the acquired imaging data as input to 3D model generation was evaluated. Six different reconstruction modes for 3D digital subtraction angiography (DSA) acquisitions were applied to eight patient-specific aneurysms. Segmentations were extracted to compare the 3D luminal surfaces. Time-dependent CFD simulations were carried out in all 48 configurations to assess the velocity and wall shear stress (WSS) variability due to the choice of reconstruction kernel.ResultsAll kernels yielded good segmentation agreement in the parent artery; deviations of the luminal surface were present at the aneurysm neck (up to 34.18%) and in distal or perforating arteries. Observations included pseudostenoses as well as noisy surfaces, depending on the selected reconstruction kernel. Consequently, the hemodynamic predictions show a mean SD of 11.09% for the aneurysm neck inflow rate, 5.07% for the centerline-based velocity magnitude, and 17.83%/9.53% for the mean/max aneurysmal WSS, respectively. In particular, vessel sections distal to the aneurysms yielded stronger variations of the CFD values.ConclusionsThe choice of reconstruction kernel for DSA data influences the segmentation result, especially for small arteries. Therefore, if precise morphology measurements or blood flow descriptions are desired, a specific reconstruction setting is required. Furthermore, research groups should be encouraged to denominate the kernel types used in future hemodynamic studies.

scholarly journals Two-Phase Non-Newtonian Pulsatile Blood Flow Simulations in a Rigid and Flexible Patient-Specific Left Coronary Artery (LCA) Exhibiting Multi-Stenosis

2021 ◽  
Vol 11 (23) ◽  
pp. 11361
Author(s):  
Abdulgaphur Athani ◽  
Nik Nazri Nik Ghazali ◽  
Irfan Anjum Badruddin ◽  
Abdullah Y. Usmani ◽  
Sarfaraz Kamangar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Left Coronary Artery ◽  
Solid Wall ◽  
Three Dimensional ◽  
Patient Specific ◽  
Maximum Pressure ◽  
Three Dimensional Model ◽  
Two Phase ◽  
Pressure Drops

Coronary artery disease (CAD) is stated as one of the most common causes of death all over the world. This article explores the influence of multi stenosis in a flexible and rigid left coronary artery (LCA) model using a multiphase blood flow system which has not yet been studied. Two-way fluid–solid interaction (FSI) is employed to achieve flow within the flexible artery model. A realistic three-dimensional model of multi-stenosed LCA was reconstructed based on computerized tomography (CT) images. The fluid domain was solved using a finite volume-based commercial software (FLUENT 2020). The fluid (blood) and solid (wall) domains were fully coupled by using the ANSYS Fluid-Structure Interaction solver. The maximum pressure drops, and wall shear stress was determined across the sever stenosis (90% AS). The higher region of displacement occurs at the pre-stenosis area compared to the other area of the left coronary artery model. An increase in blood flow velocity across the restricted regions (stenosis) in the LCA was observed, whereas the recirculation zone at the post-stenosis and bifurcation regions was noted. An overestimation of hemodynamic descriptors for the rigid models was found as compared to the FSI models.

Simulation of personalised haemodynamics by various mounting positions of a prosthetic valve using computational fluid dynamics

2019 ◽  
Vol 64 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Markus Bongert ◽  
Marius Geller ◽  
Werner Pennekamp ◽  
Volkmar Nicolas
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Heart Valve Disease ◽  
Patient Specific ◽  
Opening Angle ◽  
The European Union ◽  
Prosthetic Valves ◽  
Magnetic Resonance Imaging Mri

Abstract Diseases of the cardiovascular system account for nearly 42% of all deaths in the European Union. In Germany, approximately 12,000 patients receive surgical replacement of the aortic valve due to heart valve disease alone each year. A three-dimensional (3D) numerical model based on patient-specific anatomy derived from four-dimensional (4D) magnetic resonance imaging (MRI) data was developed to investigate preoperatively the flow-induced impact of mounting positions of aortic prosthetic valves to select the best orientation for individual patients. Systematic steady-state analysis of blood flow for different rotational mounting positions of the valve is only possible using a virtual patient model. A maximum velocity of 1 m/s was used as an inlet boundary condition, because the opening angle of the valve is at its largest at this velocity. For a comparative serial examination, it is important to define the standardised general requirements to avoid impacts other than the rotated implantation of the prosthetic aortic valve. In this study, a uniform velocity profile at the inlet for the inflow of the aortic valve and the real aortic anatomy were chosen for all simulations. An iterative process, with the weighted parameters flow resistance (1), shear stress (2) and velocity (3), was necessary to determine the best rotated orientation. Blood flow was optimal at a 45° rotation from the standard implantation orientation, which will offer a supply to the coronary arteries.

Assessment of Invasive Fractional Flow Reserve Procedures Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Yasser Abuouf ◽  
Muhamed Albadawi ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Fractional Flow Reserve ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Patient Specific ◽  
Concomitant Treatment ◽  
Fractional Flow ◽  
Flow Reserve

Abstract Coronary artery disease is the abnormal contraction of heart supply blood vessel. It may lead to major consequences such as heart attack and death. This narrowing in the coronary artery limits the oxygenated blood flow to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. Fractional Flow Reserve (FFR) is one of the most accurate methods to pinpoint the stenosis severity. The advantages of FFR are high accuracy, immediate estimation of the severity of the stenosis, and concomitant treatment using balloon or stent. Nevertheless, the main disadvantage of the FFR is being an invasive procedure that requires an incision under anesthesia. Moreover, inserting the guidewire across the stenosis may result in a ‘tight-fit’ between the vessel lumen and the guidewire. This may cause an increase in the measured pressure drop, leading to a false estimation of the blood flow parameters. To estimate the errors in diagnosis procedures, a comprehensive three-dimensional model blood flow along with guidewire is developed. Reconstructed three-dimensional coronary artery geometry from a patient-specific scan is used. Blood is considered non-Newtonian and the flow is pulsatile. The comprehensive model is numerically simulated using boundary conditions. Based on the predicted results, the ratio between pressure drop and distal dynamic pressure (CDP) is studied. The predicted results for each case are compared with the control case (the case without guidewire) and analyzed. It was found that simulating the model by placing the guidewire at a full position prior to the simulation leads to an overestimation of the CDP as it increases by 34.3%. However, simulating the procedure of guidewire insertion is more accurate. It shows that the CDP value increases by 7%.

scholarly journals Modeling autoregulation in three-dimensional simulations of retinal hemodynamics

2016 ◽  
Vol 1 (1) ◽  
pp. 88-115
Author(s):  
Matteo Aletti ◽  
Jean-Frédéric Gerbeau ◽  
Damiano Lombardi
Keyword(s):  
Experimental Data ◽  
Blood Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Blood Flow Rate ◽  
Patient Specific ◽  
Initial Attempt ◽  
Structural Part ◽  
3D Network

Purpose: Autoregulation is a mechanism necessary to maintain an approximately constant blood flow rate in the microcirculation when acute changes in systemic pressure occur. Failure of autoregulation in the retina has been associated with various diseases, including glaucoma. In this work, we propose an initial attempt to model autoregulation in a 3D network of retinal arteries.Methods: The blood flow is modeled with the time-dependent Stokes equations. The arterial wall model includes the endothelium and the smooth muscle fibers. Various simplifying assumptions lead to a fluid-structure model where the structural part appears as a boundary condition for the fluid. The numerical simulations are performed on a patient-specific network of 25 segments of retinal arteries located in the inferior temporal quadrant.Results: The simulations performed on the patient-specific artertial network have provided velocities which are in good agreement with published experimental data. In addition, the model allowed to reproduce flow rate-pressure curves which are comparable with experimental data or results obtained with 0D models. In particular, a characteristic plateau of the flow rate has been found for pressures ranging from 40 to 60 mmHg.Conclusion: This work proposes the first 3D simulation of blood flow in a real network of retinal arteries and it also incorporates an autoregulation mechanism. This can be viewed as a first step towards a more complete 3D model of the hemodynamic of the eye.

scholarly journals Effect of guidewire insertion in fractional flow reserve procedure for real geometry using computational fluid dynamics

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Yasser Abuouf ◽  
Muhamed AlBadawi ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Fractional Flow Reserve ◽  
Treatment Plan ◽  
Three Dimensional ◽  
Patient Specific ◽  
Flow Ratio ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Actual Flow

Abstract Background Coronary artery disease is an abnormal contraction of the heart supply blood vessel. It limits the oxygenated blood flow to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. Fractional flow reserve (FFR) is the most accurate method to pinpoint the stenosis severity. However, inserting the guidewire across stenosis may cause a false overestimation of severity. Methods To estimate the errors due to guidewire insertion, reconstructed three-dimensional coronary artery geometry from a patient-specific scan is used. A comprehensive three-dimensional blood flow model is developed. Blood is considered non-Newtonian and the flow is pulsatile. The model is numerically simulated using realistic boundary conditions. Results The FFR value is calculated and compared with the actual flow ratio. Additionally, the ratio between pressure drop and distal dynamic pressure (CDP) is studied. The obtained results for each case are compared and analyzed with the case without a guidewire. It was found that placing the guidewire leads to overestimating the severity of moderate stenosis. It reduces the FFR value from 0.43 to 0.33 with a 23.26% error compared to 0.44 actual flow ratio and the CDP increases from 5.31 to 7.2 with a 35.6% error. FFR value in mild stenosis does not have a significant change due to placing the guidewire. The FFR value decreases from 0.83 to 0.82 compared to the 0.83 actual flow ratio. Conclusion Consequently, physicians should consider these errors while deciding the treatment plan.

COMPUTATIONAL FLUID DYNAMICS OF TWO PATIENT-SPECIFIC SYSTEMIC TO PULMONARY SHUNTS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350005 ◽  
Author(s):  
JINLI DING ◽  
YOUJUN LIU ◽  
LINJUAN CHAI ◽  
XUE CAO ◽  
FENG WANG
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Innominate Artery ◽  
Patient Specific ◽  
Pulmonary Shunt ◽  
Computed Tomography Images ◽  
Systemic Artery

Tetralogy of Fallot is the most common cyanotic congenital heart defect. For severe cases, inserting a systemic to pulmonary shunt, which distributes part of systemic artery blood into the pulmonary artery, is the preferable palliative surgery. Based on the computed tomography images and three-dimensional geometry technologies, two patient-specific anatomical options of systemic to pulmonary shunts including the aorta to pulmonary shunt (APS) and innominate artery to pulmonary shunt (IPS) have been simulated for computational fluid dynamics. The objective of this study was to predict the hemodynamics within the shunts and confirm, through patient-specific simulations, the shunt with the optimal performance. Results indicated that both options created high velocity gradients and pressure gradients at the proximal end of the shunts. Obvious flow recirculation appeared at the inner region near the proximal end of the shunts. Part of the reverse flow from the descending aorta, left subclavian artery, left carotid artery and innominate artery was driven into the shunts during the diastolic period. The IPS provided better balanced and more adequate blood flow distributions between the systemic and pulmonary circulations. The APS provided slightly excessive pulmonary blood flow which can ultimately result in cardiac failure and pulmonary hypertension.

scholarly journals A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise

2016 ◽  
Vol 310 (9) ◽  
pp. H1242-H1258 ◽  
Author(s):  
Christopher J. Arthurs ◽  
Kevin D. Lau ◽  
Kaleab N. Asrress ◽  
Simon R. Redwood ◽  
C. Alberto Figueroa
Keyword(s):  
Mathematical Model ◽  
Heart Rate ◽  
Blood Flow ◽  
Feedback Control ◽  
Coronary Blood Flow ◽  
Feedforward Control ◽  
Three Dimensional ◽  
Aortic Pressure ◽  
Oxygen Deficit ◽  
Patient Specific

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit.

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