Method for Simulating Hemodynamic Characteristics of Left Ventricular Wall Thrombus Using CFD Technology

Abstract

The present invention discloses a method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology, which includes the following steps. Step 1: Obtain the original data of enhanced cardiac CT of the patient and the real-time aortic valve flow velocity of echocardiogram. Step 2: Import the discretized model into ADINA software. Step 3: Under the condition of maintaining boundary conditions and load conditions, perform dynamic simulation on the cardiac models corresponding to different thrombus factors to obtain the motion characteristics of blood flow in different cardiac models and the force characteristics of thrombus, and obtain the compressive stress and shear stress exerted by the surrounding blood flow field on the thrombus. The method for simulating the hemodynamic characteristics of left ventricular mural thrombus provided by the present invention uses the real enhanced cardiac CT of the patient as the model, simulates the hemodynamic parameters of echocardiogram, and uses CFD means to simulate hemodynamics, so as to explore whether the hemodynamic state of the thrombus in individual patients with left ventricular mural thrombus is prone to detachment, and further achieve the purpose of accurately predicting the risk of thrombus detachment.

Description

Technical Field

[0001] The present invention relates to the technical field of left ventricular mural thrombus research, and specifically relates to a method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology. Background Art

[0002] Left ventricular mural thrombus, as a clinically dangerous disease, is often accompanied by systemic embolism, such as stroke, renal infarction, etc. The clinical incidence has a high fatality rate and disability rate. Limited by the sample size, most current clinical studies are case reports or predictions of risk factors for thrombus formation. On the other hand, due to the too low statistical power, further analysis of relevant factors for the clinical characteristics of thrombus cannot be carried out.

[0003] For left ventricular mural thrombus, the common treatment method is anticoagulation, but such patients often need to antiplatelet at the same time, and the combined application has a greater bleeding risk. By simulating different states after thrombus formation, it is more important to efficiently and realistically identify high-risk and easily detachable thrombus in clinical work.

[0004] At present, for the left ventricular simulation carried out by using CFD software, most use regular geometric models or animal models, and fail to combine the real-time flow velocity parameters of patients, which is far from the real patient situation, and it is difficult to accurately predict the risk of thrombus detachment and difficult to be used for quantitative analysis and judgment.

[0005] In addition, compared with cardiac MRI, cardiac CT is widely carried out in primary hospitals, with good image imaging effect, simple operation, short completion time, and a wide range of application populations. As cardiac simulation imaging data, it is reliable and convenient.

[0006] Therefore, a method for simulating the hemodynamic characteristics of left ventricular mural thrombus based on CFD technology is proposed. Summary of the Invention

[0007] Aiming at the main problems mentioned in the background art, the present invention aims to provide a method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology. Based on the enhanced cardiac CT of patients, an individual-related numerical simulation model is established. By real-time measuring the hemodynamic parameters by echocardiography and using CFD software to simulate the hemodynamic behavior, the blood flow dynamic load received by the individual left ventricular mural thrombus of the patient is obtained, and further the purpose of accurately predicting the risk of thrombus detachment is achieved to solve the problems mentioned in the background art.

[0008] The above technical object of the present invention is achieved by the following technical solutions:

[0009] A method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology, comprising the following steps:

[0010] Step 1: Based on the enhanced cardiac CT data and imaging materials of the patient, establish a cardiac geometric model through CAE software, reproduce the thrombus position, morphology, and number factors in the geometric model, use tetrahedral meshes to divide the mesh of the calculation area, and obtain a discretized model;

[0011] Step 2: Import the discretized model into ADINA software. The flow field inlet adopts a velocity boundary, determine the blood flow velocity at the inlet boundary according to the echocardiogram results, and the ventricular wall adopts the MOVING WALL boundary of the ADINA special boundary. Establish the motion data of the ventricular wall within one cycle according to the echocardiogram results;

[0012] Step 3: Under the condition of maintaining the boundary conditions and load conditions, perform dynamic simulations on the cardiac models corresponding to different thrombus factors, obtain the motion characteristics of the blood flow and the force characteristics of the thrombus in different cardiac models, obtain the compressive stress and shear stress exerted by the surrounding blood flow field on the thrombus, and through numerical integration, obtain the normal and tangential blood flow loads received by the thrombus, and then evaluate the thrombus detachment risk of the cardiac models corresponding to different thrombus factors.

[0013] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein, in Step 1, the uniqueness of the controlled variables is controlled by the method of controlling variables.

[0014] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein, when considering the thrombus position and number among the controlled variables, it is assumed that the thrombus morphology is consistent.

[0015] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein, when considering the thrombus morphology among the controlled variables, it is assumed that the thrombus position and number are consistent.

[0016] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein, among the controlled variables, it is also assumed that the thrombus morphology can be determined by the diameter and height, so as to avoid the interference of the complex thrombus boundary on the analysis results.

[0017] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein, among the controlled variables, qualitative analysis is also performed on flat-bottom and pointed-top thrombi, mainly analyzing the motion characteristics of the blood flow and the force characteristics of the thrombus in the cardiac models corresponding to flat-bottom, pointed-top, and normal thrombi under the condition that the simulation conditions remain unchanged.

[0018] The above method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, wherein the entire modeling process of Step 1 is carried out in Catia. For a single thrombus, the shape characteristics of the thrombus are confirmed based on the morphological parameters of the thrombus, and it is attached to the corresponding position on the heart wall through geometric modeling. At the same time, the model is exported to ADINA in the form of x_t, and the internal flow field information is obtained by means of Boolean operation; for thrombi with different numbers, the operation processes of the above Step 1, Step 2, and Step 3 are repeated at different corresponding positions on the heart wall.

[0019] In summary, the present invention mainly has the following beneficial effects:

[0020] The method for simulating the hemodynamic characteristics of left ventricular mural thrombus provided by the present invention uses the cardiac enhanced CT of a real patient as a model, determines the boundary conditions with the hemodynamic parameters of echocardiography, and simulates the hemodynamics by means of CFD, so as to explore the probability of detachment of the hemodynamic state of the thrombus in individual patients with left ventricular mural thrombus, and further achieve the purpose of quantitatively predicting the risk of thrombus detachment. Brief Description of the Drawings

[0021] Figure 1 It is an image of a patient with left ventricular mural thrombus under echocardiography;

[0022] Figure 2 It is an image of the same patient with left ventricular mural thrombus under enhanced CT;

[0023] Figure 3 It is a model diagram of 3D three-dimensional reconstruction of left ventricular mural thrombus, and the shaded part is the thrombus;

[0024] Figure 4 It is an image of the peak velocity of aortic valve flow in the systolic phase of the patient in real time, measuring the blood flow velocity and time at three nodes: the beginning of systole (the aortic valve is about to open), the mid-systole (the aortic valve is fully open), and the end-systole (the aortic valve is closed) of the patient;

[0025] Figure 5 It is a CFD diagram of the patient at the beginning of systole when the aortic valve is about to open;

[0026] Figure 6 It is a CFD diagram of the patient in mid-systole when the aortic valve is fully open;

[0027] Figure 7 It is a CFD diagram of the patient at the end of systole when the aortic valve is closed. Detailed Embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. It should be noted that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Reference Figures 1-7 , a method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, comprising the following steps:

[0030] Step 1: According to the cardiac enhanced CT data and imaging materials of the patient, establish a cardiac geometric model through CAE software, reproduce the thrombus position, morphology, and number factors in the geometric model, and use tetrahedral meshes to divide the computational domain to obtain a discretized model;

[0031] Step 2: Import the discretized model into ADINA software. The flow field inlet adopts a velocity boundary, and the inflow boundary blood flow velocity is determined according to the echocardiogram results. The ventricular wall adopts the MOVING WALL boundary of the ADINA special boundary, and the motion data of the ventricular wall within one cycle is established according to the echocardiogram results;

[0032] Step 3: Under the condition of maintaining the boundary conditions and load conditions, perform dynamic simulations on the cardiac models corresponding to different thrombus factors, obtain the motion characteristics of the blood flow and the force characteristics of the thrombus in different cardiac models, obtain the compressive stress and shear stress exerted by the surrounding blood flow field on the thrombus, and through numerical integration, obtain the normal and tangential blood flow loads received by the thrombus, and then evaluate the thrombus detachment risk of the cardiac models corresponding to different thrombus factors.

[0033] Specifically, in this embodiment, in step 1, the uniqueness of variables is controlled by the method of controlling variables.

[0034] Specifically, in this embodiment, when considering the thrombus position and number, the control variables include assuming that the thrombus morphology is consistent.

[0035] Specifically, in this embodiment, when considering the thrombus morphology, the control variables also include assuming that the thrombus position and number are consistent.

[0036] Specifically, in this embodiment, the control variables also include assuming that the thrombus morphology can be determined by the diameter and height, so as to avoid the interference of the complex thrombus boundary on the analysis results.

[0037] Specifically, in this embodiment, the control variables further include qualitative analysis of flat-top and pointed-top thrombi. The main analysis is to analyze the motion characteristics of blood flow in the heart model corresponding to flat-top, pointed-top, and normal thrombi and the force characteristics of thrombi under the condition of ensuring the same analysis conditions.

[0038] Specifically, in this embodiment, the entire modeling process of step one is carried out in Catia. For a single thrombus, the shape parameters of the thrombus are used to confirm the external shape characteristics of the thrombus, and it is attached to the corresponding position on the heart wall through geometric modeling. At the same time, the model is exported to ADINA in the form of x_t, and the internal flow field information is obtained by means of Boolean operation; for thrombi with different numbers, the above steps one, two, and three are repeated at different positions corresponding to the heart wall.

[0039] Working principle:

[0040] (1) In the preliminary pre-experiment part, the research on the heart with different thrombus morphologies and its blood movement laws was carried out by combining medical images and the finite element method. Computer models of hearts with different thrombus morphologies were established, and the blood flow pressure and velocity at any moment in a continuous motion cycle at the corresponding positions of the heart were obtained in combination with medical images as the boundary conditions for CAE analysis. The effects of pressure and blood flow state on thrombi were evaluated.

[0041] The research combined CT scans to establish a heart model of different thrombus states, and carried out CFD analysis of relevant heart models through AIDNA software to solve the Navier-Stokes equation of blood flow motion. To make the analysis data valid, the influence of grid density on the convergence of the results was discussed at the initial stage of the research. The entire ventricle was meshed with a size of 1 mm, and the inflow boundary had a smaller size and was the key focus, with a size of 0.5 mm for meshing. To better characterize the motion characteristics of the fluid, tetrahedral elements were used to generate the mesh. The blood density was taken as 1.05e-009 ton / mm^3, and the kinematic viscosity was 3.5e-009 Mpa.s. To make the CAE analysis more consistent with the actual situation, the compressibility of the blood was considered, and its bulk modulus was set to 2 GPa. At the same time, the influence of gravity on the analysis results was considered throughout the analysis process, and the gravitational acceleration was taken as 9800 mm / s^2. To better describe the blood flow motion state in the left ventricle during the compression period, the pressure change state and velocity change state at the outlet position during a complete systolic period were obtained and used as the loading boundary conditions in the CAE analysis process; for the area surrounded by the ventricular wall around the blood, the motion of the ventricular wall was characterized by a moving boundary. The entire simulation calculation was implemented using ADINA software. For the fluid region, transient analysis was selected, and the iterative method was Euler iteration. For a period T, the time step was divided according to T / 100 to ensure the accuracy and efficiency of the analysis.

[0042] (2) Simulate different thrombus states, such as the size, shape, and location of the thrombus, to simulate and analyze the cardiac pressure distribution characteristics and blood flow characteristics under different thrombus states, so as to evaluate the influence of pressure and blood flow status on the thrombus. Try to analyze and summarize on the basis of this model for this patient when what state of the thrombus is likely to break off (because the state of the thrombus is a dynamic process and requires dynamic follow-up)

[0043] In summary:

[0044] The method for simulating the hemodynamic characteristics of left ventricular mural thrombus provided by the present invention has the following technical effects:

[0045] According to the actual heart conditions of each patient, enhanced CT images and real-time echocardiogram index simulations are carried out. For patients with existing thrombi, different states of the thrombus (size, location, number, etc.) are simulated to simulate the hemodynamic changes of the same patient under different states, so as to achieve the purpose of accurately predicting the risk of thrombus detachment.

[0046] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology, characterized in that: The steps are as follows: Step 1: Based on the original data of the enhanced cardiac CT of the patient and the real-time aortic valve flow velocity of echocardiography, establish a cardiac geometric model through CAE software, reproduce the thrombus position, shape, and number factors in the geometric model, use tetrahedral meshes to divide the mesh of the calculation area, and obtain a discretized model; Step 2: Import the discretized model into ADINA software. The flow field inlet adopts a velocity boundary, determine the blood flow velocity of the inlet boundary according to the echocardiography result, the ventricular wall adopts the MOVING WALL boundary of the ADINA special boundary, and establish the motion data of the ventricular wall within one cycle according to the echocardiography result; Step 3: Under the condition of maintaining the boundary conditions and load conditions, conduct dynamic simulations on the cardiac models corresponding to different thrombus factors, obtain the motion characteristics of the blood flow and the force characteristics of the thrombus in different cardiac models, obtain the compressive stress and shear stress exerted on the thrombus by the surrounding blood flow field, and through numerical integration, obtain the normal and tangential blood flow loads received by the thrombus, and then evaluate the thrombus detachment risk of the cardiac models corresponding to different thrombus factors.

2. A method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology according to claim 1, characterized in that: In Step 1, the uniqueness of the controlled variables is controlled by the method of controlling variables.

3. The method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology according to claim 2, wherein: The controlled variables include assuming that the thrombus shape is consistent when considering the thrombus position and number.

4. The method for simulating the hemodynamic characteristics of left ventricular mural thrombus by using CFD technology according to claim 3, characterized in that: The controlled variables also include assuming that the thrombus position and number are consistent when considering the thrombus shape.

5. A method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology according to claim 4, characterized in that: The controlled variables also include assuming that the thrombus shape can be determined by the diameter and height to avoid the interference of the complex thrombus boundary on the analysis results.

6. A method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology according to claim 5, characterized in that: The controlled variables also include conducting qualitative analysis on flat-bottom and pointed-top thrombi, mainly analyzing the motion characteristics of the blood flow and the force characteristics of the thrombus in the cardiac models corresponding to flat-bottom, pointed-top, and normal thrombi under the condition of ensuring the same analysis conditions.

7. A method for simulating the hemodynamic characteristics of left ventricular mural thrombus using CFD technology according to claim 6, characterized in that: The entire modeling process in Step 1 is carried out in catia. For a single thrombus, confirm the external shape characteristics of the thrombus according to the shape parameters of the thrombus, attach it to the corresponding position on the cardiac wall surface through geometric modeling, and at the same time export the model to ADINA in the form of x_t, and use the Boolean operation method to obtain the internal flow field information; for thrombi with different numbers, repeat the operation processes of Step 1, Step 2, and Step 3 at different positions corresponding to the cardiac wall surface.

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