Smooth Mesh Generation for Numerical Analysis of Blood Vessel Fluid Flow

2011 ◽  
Author(s):  
Juraj Culak ◽  
Yulia V. Peet ◽  
David L. Chopp
Keyword(s):  
Blood Flow ◽  
Image Segmentation ◽  
Fluid Flow ◽  
Numerical Analysis ◽  
Carotid Artery ◽  
Blood Vessel ◽  
Mesh Generation ◽  
Patient Specific ◽  
High Quality

A Matlab-based approach to image segmentation and mesh generation for creating high-quality hexagonal meshes is developed. The successful use of the procedure in patient-specific simulations of blood flow in a carotid artery is demonstrated.

scholarly journals Determinants of Cerebrovascular Reserve in Patients with Significant Carotid Stenosis

2020 ◽  
Author(s):  
Joseph P Archie
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Carotid Stenosis ◽  
Vascular Resistance ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Systemic Arterial Pressure ◽  
Patient Specific ◽  
Flow Reserve

AbstractIntroductionIn patients with 70% to 99% diameter carotid artery stenosis cerebral blood flow reserve may be protective of future ischemic cerebral events. Reserve cerebral blood flow is created by brain auto-regulation. Both cerebral blood flow reserve and cerebrovascular reactivity can be measured non-invasively. However, the factors and variables that determine the availability and magnitude and of reserve blood flow remain poorly understood. The availability of reserve cerebral blood flow is a predictor of stroke risk. The aim of this study is to employ a hemodynamic model to predict the variables and functional relationships that determine cerebral blood flow reserve in patients with significant carotid stenosis.MethodsA basic one-dimensional, three-unit (carotid, collateral and brain) energy conservation fluid mechanics blood flow model is employed. It has two distinct but adjacent blood flow components with normal cerebral blood flow at the interface. In the brain auto-regulated blood flow component cerebral blood flow is maintained normal by reserve flow. In the brain pressure dependent blood flow component cerebral blood flow is below normal because cerebral perfusion pressure is below the lower threshold value for auto-regulation. Patient specific values of collateral vascular resistance are determined from a model solution using clinically measured systemic and carotid arterial stump pressures. Collateral vascular resistance curves illustrate the model solutions for reserve and actual cerebral blood flow as a function of percent diameter carotid artery stenosis and mean systemic arterial pressure. The threshold cerebral perfusion pressure value for auto-regulation is assumed to be 50 mmHg. Normal auto-regulated regional cerebral blood flow is assumed to be 50 ml/min/100g. Cerebral blood flow and reserve blood flow solutions are given for systemic arterial pressures of 80, 90, 100, 110 and 120 mmHg and for three patient specific collateral vascular resistance values, Rw = 1.0 (mean patient value), Rw = 0.5 (lower 1 SD) and Rd = 3.0 (upper 1 SD).ResultsReserve cerebral blood flow is only available when a patients cerebral perfusion pressure is in the normal auto-regulatory range. Both actual and reserve cerebral blood flows are primarily from the carotid circulation when carotid stenosis is less than 60% diameter. Between 60% and 75% stenosis the remaining carotid blood flow reserve is utilized and at higher degrees of stenosis all reserve flow is from the collateral circulation. The primary independent variables that determine actual and reserve cerebral blood flow are mean systemic arterial pressure, degree of carotid stenosis and patient specific collateral vascular resistance. Approximate 16% of patients have collateral vascular resistance greater than 5.0 and are predicted to be at high risk of cerebral ischemia or infarction with progression to severe carotid stenosis or occlusion. The approximate 50% of patients with a collateral vascular resistance less than 1.0 are predicted to have adequate cerebral blood flow with progression to carotid occlusion, and most maintain some reserve. Clinically measured values of cerebral blood flow reserve or cerebrovascular reactivity are predicted to be unreliable without consideration of systemic arterial pressure and degree of carotid stenosis. Reserve cerebral blood flow values measured in patients with only moderate 60% to 70% carotid stenosis are in general too high and variable to be of clinical value, but are most reliable when measured near 80% diameter stenosis and considered as percent of the maximum reserve blood flow. Patient specific measured reserve blood flow values can be inserted into the model to calculate the collateral vascular resistance.ConclusionsPredicting cerebral blood flow reserve in patients with significant carotid stenosis is complex and multifactorial. A simple cerebrovascular model predicts that patient specific collateral vascular resistance is an excellent predictor of reserve cerebral blood flow in patients with significant carotid stenosis. Cerebral blood flow reserve measurements are of limited value without accounting for systemic pressure and actual percent carotid stenosis. Asymptomatic patients with severe carotid artery stenosis and a collateral vascular resistance greater than 1.0 are at increased risk of cerebral ischemia and may benefit from carotid endarterectomy.

Evaluation and Analysis of Cardiovascular Function in Intensive Care Unit Patients by Ultrasound Image Segmentation Based on Deep Learning

2020 ◽  
Vol 10 (8) ◽  
pp. 1892-1898
Author(s):  
Jiaqi Shen ◽  
Fangfang Huang ◽  
Myers Ulrich
Keyword(s):  
Image Segmentation ◽  
Deep Learning ◽  
Carotid Artery ◽  
Blood Vessel ◽  
Nerve Cell ◽  
Clinical Application ◽  
Learning Algorithm ◽  
Linear Filter ◽  
Multi Scale ◽  
Deep Learning Algorithm

Many studies have shown that cardiovascular disease has become one of the major diseases leading to death in the world. Therefore, it is a very meaningful topic to use image segmentation technology to segment blood vessels for clinical application. In order to automatically extract the features of blood vessel images in the process of segmentation, the deep learning algorithm is combined with image segmentation technology to segment the nerve cell membrane and carotid artery images of ICU patients, and to segment the blood vessel images from a multi-dimensional perspective. The relevant data are collected to observe the effect of this model. The results show that the three-dimensional multi-scale linear filter has a good effect on carotid artery segmentation in the image segmentation of nerve cell membranes and carotid artery. When analyzing the accuracy of vascular image segmentation from network parameters and training parameters, it is found that the accuracy of the threedimensional multi-scale linear filter can reach about 85%. Therefore, it can be found that the combination of deep learning algorithm and image segmentation technology has a good segmentation effect, and the segmentation accuracy is also high. The experiment achieves the desired effect, which provides experimental basis for the clinical application of the vascular image segmentation technology.

Analytical Prediction of the Heat Transfer From a Blood Vessel Near the Skin Surface Cooled by a Symmetrical Strip

1975 ◽  
Vol 97 (1) ◽  
pp. 61-65 ◽  
Author(s):  
J. C. Chato ◽  
A. Shitzer
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Steady State ◽  
Carotid Artery ◽  
Blood Vessel ◽  
Analytical Method ◽  
Skin Surface ◽  
Analytical Prediction ◽  
Flow Through ◽  
Optimum Width

A steady-state analytical method has been developed to estimate the amount of heat extracted from a blood vessel running close to the skin surface which is cooled in a symmetrical fashion by a cooling strip. The results indicate that the optimum width of a cooling strip is approximately three times the depth to the centerline of the blood vessel. The heat extracted from a blood vessel similar to the carotid artery by such a strip is about 0.9 w/m-deg C, which is too small to affect significantly the temperature of the blood flow through a main blood vessel, such as the carotid artery.

Analysis of emboli and blood flow in the ophthalmic artery to understand retinal artery occlusion

2014 ◽  
Vol 59 (6) ◽  
Author(s):  
Tim A.S. Kaufmann ◽  
Christoph Leisser ◽  
Jeannie Gemsa ◽  
Ulrich Steinseifer
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Ophthalmic Artery ◽  
Internal Carotid ◽  
Retinal Artery Occlusion ◽  
Artery Occlusion ◽  
Patient Specific ◽  
Retinal Artery ◽  
The Brain

AbstractRetinal artery occlusion (RAO) is a common ocular vascular occlusive disorder that may lead to partial or complete retinal ischemia with sudden visual deterio ration and visual field defects. Although RAO has been investigated since 1859, the main mechanism is still not fully understood. While hypoperfusion of the ophthalmic artery (OA) due to severe stenosis of the internal carotid artery might lead to RAO, emboli are assumed to be the main reason. Intra-arterial thrombolysis is not a sufficient treatment for RAO, and current research is mainly focused on risk factors. In this study, a computational fluid dynamic model is presented to analyse flow conditions and clot behaviour at the junction of the internal carotid artery and OA based on a realistic geometry from a RAO patient. Clot diameters varied between 5 and 200 μm, and the probability of clots reaching the OA or being washed into the brain was analysed. Results show sufficient blood flow and perfusion pressure at the end of OA. The probability that clots from the main blood flow will to be washed into the brain is 7.32±1.08%. A wall shear stress hotspot is observed at the curvature proximal to the internal carotid artery/OA junction. Clots released from this hotspot have a higher probability of causing RAO. The occurrence of such patient-specific pathophysiologies will have to be considered in the future.

scholarly journals Numerical modelling of redo of the prosthetic heart valve: hemodynamics

2019 ◽  
Vol 23 (3) ◽  
pp. 30
Author(s):  
E. A. Ovcharenko ◽  
P. S. Onishchenko ◽  
K. Yu. Klyshnikov ◽  
V. I. Ganyukov ◽  
A. A. Shilov ◽  
...  
Keyword(s):  
Blood Flow ◽  
Numerical Analysis ◽  
Aortic Valve ◽  
Conflict Of Interest ◽  
Computer Modelling ◽  
Haemodynamic Effects ◽  
Patient Specific ◽  
Valve In Valve ◽  
Blood Flow Velocities ◽  
Flow Velocities

<p><strong>Aim.</strong> In this article, we report a numerical analysis of the causes and haemodynamic effects of paraprosthetic regurgitation during redo transcatheter prosthesis of the aortic valve with the “valve-in-valve” technique with respect to the predictive value of computer modelling.<br /><strong>Methods.</strong> We used numerical analysis of haemodynamics for a patient-specific simulation of blood flow in the “valve-in-valve” complex formed from a failed framed and transcatheter self-expanding aortic valve bioprosthesis. The three-dimensional computer models of the aortic root, the frame, and the transcatheter bioprosthesis were reconstructed using the multislice computed tomographic data of patient T. aged 61 years who underwent “valve-in-valve” implantation of a self-expanding valve (CoreValve™; Medtronic, Dublin, Ireland). Computer modelling was performed with the immersed boundary method, considering the haemodynamic characteristics of the patient which were obtained by postoperative transthoracic echocardiography. Qualitative and quantitative indicators of blood flow average and peak blood flow velocities, wall shear, viscous stress, and Reynolds stress were analysed, as were the distributions of these indicators in the blood flow volume of the model. Particular attention was paid to these indicators with regard to the area of observation of the first-degree paraprosthetic regurgitation in the zone of mitral–aortic contact; such regurgitation was clinically observed at 6 months.<br /><strong>Results.</strong> In numerical simulations, high blood flow velocities in the region of interest (the area of the paraprosthetic blood leakage) as well as stresses (viscous and Reynolds stresses) do not generally cause substantial mechanical destruction of red blood cells because of the short exposure time. In the wall of the fistula, the high shear stress that results from the simulation of high blood flow velocities can initiate thrombosis with the participation of von Willebrand factor in the case of endothelial inflow of the primary bioprosthesis with dysfunction. However, these effects were not clinically observed.<br /><strong>Conclusion.</strong> As a result of clinically observed first-degree paraprosthetic regurgitation caused by the low position of the CoreValve™ transcatheter prosthesis in relation to the primary frame bioprosthesis, the contact area of the prosthesis-in-prosthesis was reduced. The patient-specific methods used to assess haemodynamic effects arising from transcatheter prosthetics satisfactorily reproduced the clinical picture of paraprosthetic regurgitation and can form the basis of numerical prognostic models of similar interventions.</p><p>Received 12 June 2019. Revised 31 October 2019. Accepted 6 November 2019.</p><p><strong>Funding:</strong> The research is supported by a grant of the Russian Science Foundation (project No. 18-75-10061).</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p>

An Approach on Fluid-Structure Interaction for Hemodynamics of Carotid Arteries

2012 ◽  
Author(s):  
Sang Hyuk Lee ◽  
Seongwon Kang ◽  
Nahmkeon Hur
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
Solid Mechanics ◽  
Fluid Structure Interaction ◽  
Blood Rheology ◽  
Numerical Approach ◽  
Patient Specific ◽  
Circulation System ◽  
Fluid Structure ◽  
Structure Interaction

In the present study, a problem of the hemodynamic fluid-structure interaction (FSI) in the carotid artery was analyzed using a numerical approach. To predict the blood flow and arterial deformation, a framework for the FSI analysis was developed by coupling computational fluid dynamics (CFD) and solid mechanics (CSM) approaches. Using this framework, the hemodynamics of the carotid artery was simulated with the patient-specific clinical data of the arterial geometry, pulsatile blood flow and blood rheology. It is found that the hemodynamic characteristics of the carotid artery are significantly affected by its geometric factors and flow conditions, and relatively low values of the wall shear stress were observed in the post-plaque dilated region of the carotid bifurcated area. Since these characteristics of the carotid artery are affected by the cerebral circulation system, the effects of the cardiac output and the distal vascular resistance on hemodynamics were also analyzed.

Sign in / Sign up

Export Citation Format

Share Document