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CN-121983250-A - Construction method of left auricle hemodynamic simulation system

CN121983250ACN 121983250 ACN121983250 ACN 121983250ACN-121983250-A

Abstract

The invention relates to the technical field of medical treatment and discloses a construction method of a left auricle hemodynamic simulation system, which comprises the following core steps of firstly, collecting noninvasive transthoracic echocardiography and heart enhancement CT image data of a patient; and finally, carrying out hemodynamic simulation on the left atrium and the left auricle by utilizing a CFD technology on the basis of the model, and accurately calculating hemodynamic parameters such as blood flow velocity at the opening of the left auricle. The invention has the beneficial effects of realizing completely noninvasive, accurate and quantitative evaluation of the blood flow state of the left auricle and effectively replacing the traditional invasive transesophageal ultrasonic examination. The method remarkably improves the comfort level and the inspection safety of patients, avoids operation related risks, improves the feasibility and the efficiency of screening, and has important value for clinical management of stroke risks of patients suffering from atrial fibrillation.

Inventors

  • GE LAN
  • CHEN TAO
  • WANG QINGSONG
  • WANG XINYAN
  • SONG TINGTING
  • LI JIAN
  • SHI XIANGMIN
  • GUO JUN
  • CHEN YUNDAI

Assignees

  • 中国人民解放军总医院第六医学中心

Dates

Publication Date
20260505
Application Date
20251114

Claims (8)

  1. 1. A method of constructing a left atrial appendage hemodynamic simulation system, the method comprising: step 1, selecting a heart CTA and a non-valve atrial fibrillation patient subjected to transthoracic heart echocardiography examination; step 2, collecting clinical information, namely collecting imaging information of a patient, including a transthoracic echocardiogram and a heart CTA image; step 3, constructing a left atrium and left auricle three-dimensional structure model based on heart enhancement CTA data; Step 4, optimizing the three-dimensional structural model of the left atrium and the left auricle, and performing surface fitting on the three-dimensional structural model of the atrium and the left auricle; step5, constructing a pulmonary vein inlet and a mitral valve outlet of the left atrium; Step 6, meshing the left atrium and the left auricle structure model; step 7, extracting boundary conditions of the hydrodynamic model; step 8, simulating the hemodynamic state of the left atrium and the left auricle by using CFX: And 9, performing operation POST-processing, and calculating TAWSS, OSI, RRT, ECAP, RT and other parameters representing the hemodynamic states of the left atrium and the left auricle by using ANSYS CFD-POST.
  2. 2. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the step of constructing a three-dimensional structural model of the left atrium and the left atrial appendage based on the heart enhanced CTA data in step 3 comprises: Step 3.1, data importing and phase selecting, namely importing cardiac CT image data, selecting ventricular systole as an analysis phase, and entering a left auricle analysis module; step 3.2, preliminary reconstruction of the left atrium, namely generating an initial three-dimensional model of the left atrium, the left auricle and the pulmonary vein root in a seed filling mode by using a 'growing left atrium' function; Step 3.3, model trimming and correction, namely checking the model in a three-dimensional view and a multi-plane view, manually trimming the erroneously included adjacent structures (such as the left ventricle and the aorta), and finishing the accurate extraction of the left atrium cavity; step 3.4, defining a left auricle opening plane, namely selecting the tail end of the left auricle, generating a reference connecting line, and adjusting and confirming the accurate position and direction of the left auricle opening under a plurality of chamfer surface windows; 3.5, finely correcting the volume of the left auricle, namely ensuring that the left auricle cavity is completely filled under three orthogonal chamfer surface windows, and finally correcting the shape and the volume of the left auricle cavity; Step 3.6, parameter measurement and recording, wherein the system automatically calculates and records key morphological parameters such as left atrium volume, left auricle depth, long diameter, split leaf condition and the like; generating a printable three-dimensional model, namely generating a left atrium-left auricle integrated three-dimensional structure suitable for 3D printing based on the corrected model; and 3.8, deriving a model, namely deriving a final three-dimensional geometric model in a stl format for subsequent hydrodynamic analysis.
  3. 3. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the optimizing the three-dimensional structural model of the left atrium and the left atrial appendage in step 4 comprises the step of fitting a curved surface to the three-dimensional structural model of the atrium and the left atrial appendage: step 4.1, importing a model, namely importing an initial stl file into geometric processing software, and adopting a default sampling rate and a default unit; Step 4.2, creating a flow inlet and a flow outlet, namely cutting an inlet and an outlet of a left atrium by using a sheet cutting function to be perpendicular to the running direction of a pulmonary vein and the plane of a mitral valve respectively; step 4.3, grid reconstruction and smoothing, namely setting the side length of a target grid, re-scribing the grid, then loosening and smoothing, and deleting nails to optimize the quality of the grid; step 4.4, repairing and checking the model, namely filling the surface holes, checking abnormal structures in the cavity by using a view cutting tool, and performing local editing and smoothing; Step 4.5, contour line arrangement and curved surface sheet generation, namely detecting and manually drawing contour lines, ensuring that the curved surface sheets are automatically constructed and uniformly arranged after the surface of the model is completely covered, and refining the left auricle area; Step 4.6, generating a solid curved surface, namely constructing a grid based on the arranged curved surface sheets, and fitting to generate a final combined curved surface; and 4.7, model export, namely saving and exporting the processed geometric model into a STEP format file for subsequent hydrodynamic calculation.
  4. 4. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the constructing the pulmonary vein inlet and the mitral valve outlet of the left atrium in step 5 comprises: Step 5.1, preparing and checking a model, namely opening left atrium and left auricle geometry files in SolidWorks, checking the surface integrity of the model, and ensuring no gap; Step 5.2, establishing a sagittal reference standard, namely inserting and moving a right-view reference plane in parallel to establish a new reference plane which can cut into the plane of the left pulmonary vein and the mitral valve; drawing a sagittal plane reference line, namely drawing a sketch straight line on the reference plane to be parallel to the upper left pulmonary vein, the lower left pulmonary vein, the left auricle opening and the mitral valve outlet plane; Step 5.4, creating a vertical reference plane of the key structure, namely, based on the reference line and the right-view reference plane in the step 5.3, creating new reference planes respectively perpendicular to the four key structure planes; Step 5.5, establishing a coronal plane reference datum and a reference line, namely inserting and parallelly moving a forward looking datum plane, establishing a new datum plane which can cut into the right pulmonary vein, drawing a reference line parallel to the right upper and right lower pulmonary veins on the new datum plane, and further establishing a datum plane perpendicular to the new datum plane; Step 5.6, dividing the left auricle, namely dividing the left auricle from the left atrium main body by using the created left auricle opening reference surface as a cutting tool to form independent entities; 5.7, dividing the inlet and the outlet and creating a runner, namely dividing the inlet and the outlet by using the reference surfaces of the rest pulmonary veins and the mitral valve outlets, and stretching all inlet and outlet planes outwards by 200mm on the basis of the dividing, so as to form a flow extension section; and 5.8, deriving a model, and saving the fluid domain geometric model which is finally processed as a STEP AP214 format file.
  5. 5. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the meshing of the left atrial and left atrial appendage structural models in step 6 comprises: Step 6.1, initializing an item, namely starting an Ansys Workbench, creating a grid system, and importing a geometric file of a left atrium-left auricle; step 6.2, confirming and naming the geometric structures, namely checking the consistency of the model part and the anatomical structure of the patient, and naming main geometric bodies such as a left atrium, a left auricle, an inlet of each pulmonary vein, an outlet of a mitral valve and the like; step 6.3, boundary naming is carried out on the wall surfaces of all the geometric bodies, the contact surfaces with other components and the outlets systematically; step 6.4, global grid strategy setting, namely inserting global expansion (boundary layer) setting, selecting all geometric bodies, and limiting the boundary range to all wall surfaces named as wall; Defining basic grid parameters, namely setting physical preference as CFD, designating basic unit size (such as 0.001 m), starting curvature capturing and grid cleaning, and configuring an expansion layer as smooth transition, wherein the maximum is 5 layers; step 6.6, generating an initial grid, namely firstly generating a global tetrahedral grid containing all components; Step 6.7, encrypting the contact area, namely freezing the parts except the left atrium and the left auricle, applying smaller contact size (such as 0.0005 m) on the contact surface between the parts, and generating an encrypted contact area grid; step 6.8, local encryption of the left auricle, namely freezing the left atrium geometry, applying stricter grid size control (such as 0.0005 meter) to the left auricle area, and carrying out local grid refinement; step 6.9, grid quality verification, namely creating a cross section check grid, and confirming that the grid density of the left atrial appendage and the contact area is obviously higher than that of the main area of the left atrium, so as to meet the calculation requirement; and 6.10, outputting the file, namely saving project engineering files, and exporting the project engineering files into a cgns-format grid file for subsequent CFD calculation.
  6. 6. The method for constructing a left auricle hemodynamic simulation system according to claim 1, wherein the step of extracting the boundary condition of the model in step 7 is: Step 7.1, data importing and coordinate calibrating, namely running a program HaoCurve, importing a mitral valve blood flow spectrum image, and establishing a digital coordinate system according to the coordinate axis of the mitral valve blood flow spectrum image; step 7.2, digitizing the velocity curve, namely, carrying out point-by-point tracing on a spectrogram to generate a blood flow velocity-time curve in a complete cardiac cycle; step 7.3, time sequence standardization, namely discretizing a continuous speed curve by taking 0.01 second as a time step and deriving the continuous speed curve as a time-speed data pair; Step 7.4, cycle expansion and duration recording, namely repeating the process, constructing a speed curve of 5 continuous cardiac cycles, and recording the duration of each cycle; and 7.5, exporting the boundary condition file, namely exporting the finally processed multi-cycle speed time series data into a TXT format file for subsequent CFD simulation.
  7. 7. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the simulating left atrial appendage and left atrial appendage hemodynamic conditions using CFX in step 8 comprises: Step 8.1, creating a project and an importing grid, namely creating a general flow field analysis project and importing a cgns grid file of a left atrium-left auricle; Step 8.2, defining a calculation domain and a material, namely creating a fluid domain named "blood", setting the fluid domain as continuous medium and laminar flow, and adding "RESIDENCE TIME" as an additional variable; setting steady-state inlet boundary conditions, namely setting four pulmonary vein inlets (inlet 1-inlet 4) as pressure inlets (0 mmHg), wherein three velocity components are defined by pulmonary vein average velocity calculated by MATLAB; Setting a steady-state outlet boundary condition, namely setting a mitral valve outlet (outlet) as a speed outlet, wherein the speed of the mitral valve outlet is defined by a mitral valve blood flow spectrum curve extracted by MATLAB; Step 8.5, defining inter-domain interfaces by sequentially creating and pairing interfaces between all fluid domains (e.g. inlet1tola-latoinlet1, latolaa-laatola); Step 8.6, configuring a steady state solver control, namely setting the maximum iteration number as 200 steps and setting a target residual error (RMS) as 0.001; Step 8.7, executing steady state calculation and obtaining an initial value, namely running steady state solving, wherein the calculation result is used as an initial flow field of transient simulation; Step 8.8, defining a transient entry velocity Function, namely creating a custom Function (Function 1), and importing pulmonary venous blood flow velocity-time data which is generated by MATLAB and covers 5 cardiac cycles; Step 8.9, creating a transient speed Expression, namely a new Expression (Expression 1), which is defined as a Function created in the last step, namely Function 1 (t); step 8.10, configuring a transient solver, namely changing the analysis type into transient, setting the total time and time step (such as 0.01 s), and setting the maximum iteration number to be 100; step 8.11, applying transient boundary conditions, namely changing the boundary condition types of all pulmonary vein inlets into speed inlets, wherein the values of the boundary condition types are defined by an Expression 1; Step 8.12, setting a monitoring point and an output control, namely defining a speed monitoring point in the center of the left auricle opening plane; Defining flow monitoring expressions, namely creating an inlet total flow monitoring (massflow _inlet) expression and an outlet flow monitoring (massflow _outlet) expression to monitor the flow conservation of a calculation domain in real time; step 8.14, executing transient calculation, namely starting a transient solver to operate by taking a steady-state calculation result as an initial value; and 8.15, after finishing the POST-processing and data extraction, entering a CFD-POST POST-processing module.
  8. 8. The method for constructing a left atrial appendage hemodynamic simulation system of claim 1, wherein the step of performing the POST-operation processing in step 9 includes the steps of calculating parameters representing left atrial and left atrial appendage hemodynamic states using ANSYS CFD-POST calculations TAWSS, OSI, RRT, ECAP and RT, etc: Step 9.1, data derivation, namely, in CFD-POST, deriving wall shear force component data of a left atrium and a left auricle of a 5 th cardiac cycle to a CSV file; step 9.2, calculating external parameters, namely processing the derived data by utilizing a MATLAB program, and calculating TAWSS, OSI and RRT parameters of the left atrium and the left auricle; Step 9.3, mapping and visualizing the result, namely guiding the parameter result obtained by MATLAB calculation back to the CFD-POST, mapping the parameter result to a corresponding geometric model, and generating TAWSS, OSI, RRT and RT distribution cloud images; Step 9.4, calculating derivative parameters ECAP, namely, calculating and displaying a distribution cloud chart of endothelial cell activation potential energy by creating an expression ECAP=OSI/TAWSS based on mapped TAWSS and OSI results; Quantitatively recording the characteristic values of TAWSS, OSI, RRT, ECAP and RT of the left atrium and left auricle area; Step 9.6, assessing the key flow rate by using the calculator function to extract and record the blood flow velocity of the left atrial appendage opening plane in a complete cardiac cycle.

Description

Construction method of left auricle hemodynamic simulation system Technical Field The invention relates to the technical field of medical treatment, in particular to a construction method of a left auricle hemodynamic simulation system. Background Atrial fibrillation (atrial fibrillation) is the most clinically common arrhythmia, and its most serious complications are cerebral stroke and systemic embolism caused by left atrial appendage thrombosis and abscission. Numerous studies have previously demonstrated that blood flow velocity at the left atrial appendage opening is a key hemodynamic index for assessing blood stasis status and thrombus formation risk therein. Currently, this index is measured clinically, mainly by transesophageal ultrasound (TEE). However, TEE, as an invasive procedure, has risks of complications such as poor patient tolerance and esophageal mucosal damage. In addition, the examination has high technical requirements for operating doctors, and the factors limit the popularization and application of the TEE as a conventional screening tool in a wide atrial fibrillation patient group, so that the risk of left atrial appendage thrombosis of a large number of patients cannot be evaluated conveniently and timely. To overcome the originality of TEE, clinic is expected to look at other non-invasive imaging means, but all have obvious defects, and effective substitution is difficult to realize. On the one hand, the conventional transthoracic echocardiography is completely noninvasive, but is limited by factors such as acoustic window conditions, obesity, pulmonary gas interference and the like of a patient, the acquired image quality is not stable enough, the deep structure of the left auricle is difficult to clearly and reliably display, and the low-speed blood flow signal in the deep structure cannot be accurately captured. On the other hand, cardiac enhancement Computed Tomography (CTA) can reconstruct the anatomical morphology of the left atrial appendage in three dimensions with high resolution, accurately show its size, leaflet and internal myogenic trabecular structure, but CTA is essentially a "static" anatomical imaging technique that cannot directly provide critical "dynamic" hemodynamic parameters such as blood flow velocity, wall shear stress, etc. Although the heart nuclear magnetic resonance examination can realize noninvasive evaluation of the hemodynamic state of the heart, the effective evaluation of the blood flow in the left auricle cannot be realized at present due to the thinner wall of the left auricle. Therefore, the existing noninvasive imaging technology has obvious short plates in the aspects of left auricle imaging reliability and functional evaluation, and forms a technical bottleneck of 'disjoint of anatomical structure and blood flow functional information', so that the aim of noninvasively and accurately evaluating the blood flow dynamic state of the left auricle is always not realized. Disclosure of Invention In order to overcome the above-mentioned drawbacks of the prior art. The invention applies the multi-mode noninvasive image fusion and computational fluid dynamics simulation technology to the hemodynamic evaluation of the left auricle for the first time. Specifically, the method firstly fuses complementary information of a transthoracic echocardiogram (providing an initial boundary condition of blood flow velocity) and a heart enhancement CTA (providing an accurate individualized three-dimensional anatomical model) to construct a highly simulated left auricle fluid-solid coupling model. Then, by using computational fluid dynamics technology, numerical simulation is performed on the model to accurately solve the flow field distribution in the left auricle, and key blood flow velocity and other derivative hemodynamic parameters (such as endothelial cell shear stress, blood flow residence time and the like) at the opening of the model are quantitatively calculated. The successful implementation of the technical path realizes the accurate and quantitative evaluation of the left auricle hemodynamic state from the anatomical form to the physiological function on the premise of being completely noninvasive for the first time, and the accuracy of the method can be compared with the invasive TEE measurement. The technical aim of the invention is realized by the following technical scheme that the construction method of the left auricle hemodynamic simulation system comprises the following steps: step 1, selecting a heart CTA and a non-valve atrial fibrillation patient subjected to transthoracic heart echocardiography examination; step 2, collecting clinical information, namely collecting imaging information of a patient, including a transthoracic echocardiogram and a heart CTA image; step 3, constructing a left atrium and left auricle three-dimensional structure model based on heart enhancement CTA data; Step 4, optimizing the three-dimensional structural model of