A fluid-structure interaction numerical simulation method based on an interventional aortic valve

Abstract

The application discloses a fluid-structure coupling numerical simulation method based on an intervention aortic valve, and comprises the following steps: performing heart dual-source enhanced CT and heart ultrasound on a patient after TAVR; reconstructing a left ventricle, an aortic sinus and an ascending aorta of the heart by using a heart dual-source enhanced CT file, reconstructing a valve support and an artificial valve leaflet of the TAVR, and drawing a curve of left ventricle volume change with time; establishing a support and a valve leaflet model of the TAVR valve according to support data of the TAVR valve, adjusting the position of the support and the valve leaflet model of the TAVR valve by using the reconstructed support structure of the TAVR valve; meshing the adjusted support and valve leaflet model of the TAVR valve, taking the curve of the left ventricle volume change with time as an inlet condition, determining fluid parameters, and performing fluid-structure coupling simulation to obtain a simulation result; and correcting the simulation result by using a heart ultrasound file to obtain an accurate fluid-structure coupling simulation result of the TAVR valve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aortic valve fluid-structure coupling, in particular to a fluid-structure coupling numerical simulation method based on an interventional aortic valve. BACKGROUND

[0002] Transcatheter aortic valve replacement (TAVR) is the latest surgical treatment for critically ill elderly patients with aortic valve disease. Compared with traditional aortic valve replacement surgery, the early risk of surgery is relatively low, and the short-term and long-term effects are recognized.

[0003] Related studies have shown that due to the deformable characteristics of the TAVR valve stent, after implantation in the human body, it will deform to varying degrees due to the patient's own aortic valve disease, resulting in the valve not being able to achieve the functional indicators when designed in vitro, often resulting in the valve leaflets not being able to fully open or close, and then leading to valve stenosis or insufficiency. The irregular deformation of the TAVR valve leaflet can cause abnormal local stress of the TAVR valve, which can affect the short-term and long-term function of the TAVR valve and the service life of the valve, and affect the prognosis of the patient. Current evaluation of TAVR postoperative valve function is still limited to simple imaging evaluation after image acquisition using ultrasound or CT, focusing on valve stenosis, regurgitation degree, and valve displacement, and perivalvular leakage complications. A few post-processing analysis techniques only focus on the stress of the TAVR stent on the surrounding blood vessels and the influence of coronary blood flow, and do not focus on the evaluation of the valve function itself and the local mechanical characteristics. A few scholars use standardized models of the ideal state of the interventional valve after implantation to evaluate the valve function by fluid-structure coupling, but the stent structure of the TAVR valve after implantation in the human body is deformed by the extrusion of the patient's own valve leaflet and annulus-related tissues. The actual shape and function are very different from the standardized model, resulting in fluid-structure coupling results that cannot reflect the valve function of the patient with a real implanted TAVR valve. Therefore, the current evaluation method cannot provide a reliable prediction standard for the future function of the valve, and it is also difficult to help researchers improve the valve design and provide preoperative surgical effect prediction. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a fluid-structure coupling numerical simulation method based on an interventional aortic valve, which is more accurate in fluid-structure coupling numerical simulation.

[0005] To achieve the above technical purposes, the present application adopts the following technical solutions: a fluid-structure coupling numerical simulation method based on an interventional aortic valve, specifically comprising the following steps:

[0006] Step 1, respectively perform cardiac dual-source enhanced CT and cardiac ultrasound on the patient after TAVR, export the cardiac dual-source enhanced CT file and the cardiac ultrasound file in Dicom format;

[0007] Step 2, import the cardiac dual-source enhanced CT file exported in Dicom format into Mimics software, reconstruct the left ventricle, aortic sinus and ascending aorta, and reconstruct the valve stent and artificial valve leaflet of TAVR, and export the CT reconstructed TAVR valve stent structure in stl file;

[0008] Step 3, use Mimics software to calculate the left ventricular volume of each sequence of the reconstructed left ventricle, aortic sinus and ascending aorta in step 2, and draw the curve of the left ventricular volume change with time according to the left ventricular volume difference between the adjacent 10% cardiac cycles after the left ventricular reconstruction and the heart rate at the time of sampling of the cardiac dual-source enhanced CT;

[0009] Step 4, establish the stent and valve leaflet model of TAVR valve according to the in-vitro measured stent data of TAVR valve by Solidworks software;

[0010] Step 5, import the CT reconstructed TAVR valve stent structure exported in stl file in step 2 into the TAVR valve stent and valve leaflet model established in step 4, adjust the position of the corresponding point on the TAVR valve stent and valve leaflet model according to the position of each point on the CT reconstructed TAVR valve stent structure, so that the adjusted TAVR valve stent and valve leaflet model are completely coincided with the CT reconstructed TAVR valve stent structure;

[0011] Step 6, mesh the adjusted TAVR valve stent and valve leaflet model, take the curve of the left ventricular volume change with time drawn in step 3 as the inlet condition in systole, and take the pressure change curve of the left ventricle and aorta as the inlet condition in diastole, and perform fluid-structure coupling simulation according to the fluid parameters determined by the patient's blood test results, to obtain the simulation results of the opening and closing shape of the valve and the flow velocity spectrum of the valve blood flow;

[0012] Step 7, use the Dicom format exported cardiac ultrasound file in step 1 to correct the simulation results, and obtain the accurate fluid-structure coupling simulation results of TAVR valve.

[0013] Further, the cardiac dual-source enhanced CT is controlled by electrocardiogram, the sequence is split every 10% cardiac cycle, the best systolic and diastolic sequences are determined, and the split sequence is exported as a cardiac dual-source enhanced CT file in Dicom format.

[0014] Further, the cardiac ultrasound is connected to the electrocardiogram analog lead for 3-5 consecutive cardiac cycles, and the aortic valve two-dimensional and three-dimensional motion images and the Doppler aortic valve forward blood flow spectrum are collected, and the cardiac ultrasound file is exported in the Dicom format.

[0015] Further, the process of drawing the curve of the left ventricular volume change over time is as follows: the left ventricular three-dimensional model of each sequence is extracted and the volume is calculated, and the volume parameter V LV (t) is obtained according to the heart rate when the dual-source enhanced CT is sampled, and the curve of the left ventricular volume change over time is drawn with the time point t as the horizontal coordinate and the volume parameter V LV (t) as the vertical coordinate. LV The rate of change of the curve of the left ventricular volume change over time is R= (V LV (t(X+1))-V LV (t(X)) is the left ventricular volume at the corresponding time point t(X), and V LV (t(X+1)) is the left ventricular volume at the corresponding time point t(X+1).

[0016] Further, the stent data of the TAVR valve includes: the stent wire diameter, the stent height, the spatial coordinates of all metal intersections of the stent, the cross-sectional diameters of multiple layers of the stent, and the spatial coordinates of all suture points of the stent leaflets and the stent structure.

[0017] Further, the specific process of step 7 is as follows: the valve opening shape, area and flow velocity pressure difference of the intervention valve measured from the patient's body in the cardiac ultrasound file exported in the Dicom format are used as references to correct the simulation results, so as to obtain accurate fluid-structure coupling simulation results of the TAVR valve.

[0018] Further, the present application also provides a computer readable storage medium storing a computer program, wherein the computer program enables a computer to execute the fluid-structure coupling numerical simulation method based on an intervention aortic valve.

[0019] Further, the present application also provides an electronic device comprising: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to realize the fluid-structure coupling numerical simulation method based on an intervention aortic valve.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The present application establishes the stent and valve leaflet model of the TAVR valve based on the fluid-structure coupling simulation with the in-vitro measured TAVR valve stent data, adjusts the stent and valve leaflet model of the TAVR valve according to the CT reconstructed TAVR valve stent structure, since the TAVR valve stent itself is an industrial product with regular structure and fixed intersection points of the metal wire structure on the stent, the overall morphology of the TAVR valve stent can be accurately simulated by adjusting the positions of the corresponding metal wire intersection points accurately according to the in-vitro measured TAVR valve stent data and the CT reconstructed TAVR valve stent structure, and the stent and valve leaflet model of the TAVR valve is based on the computer-drawn model, which can achieve no artifact distortion and small workload of the later drawn grid, and greatly reduces the operation difficulty and workload of the later computer simulation calculation.

[0022] (2) The present application meshes the adjusted TAVR valve stent and valve leaflet model, takes the curve of the change of the left ventricular volume of the heart with time as the inlet condition in the systole, takes the central chamber and aortic pressure change curve as the inlet condition in the diastole, and carries out fluid-structure coupling simulation according to the fluid parameters determined by the blood test results of the patient, so as to more accurately reflect the actual left ventricular pressure change of the patient in the systole.

[0023] (3) The present application corrects the simulation results by the heart ultrasound file to obtain accurate fluid-structure coupling simulation results of the TAVR valve, avoids using in-vitro simulation as the source of the correction parameter of the fluid-structure coupling data of the patient, uses the data of the patient himself, is closer to the real situation, and is more accurate and reliable in calibration, and saves the time and economic cost of in-vitro calibration, and improves the reliability of correction by using the heart ultrasound data of the patient himself as the correction parameter. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the fluid-structure coupling numerical simulation method based on the intervention aortic valve of the present application is shown in the figure.

[0025] Figure 2 The comparison chart of the adjusted TAVR valve stent and valve leaflet model in the present application and the traditional TAVR valve stent based on CT extraction is shown in the figure, wherein, Figure 2 (a) in the figure is a schematic diagram of the adjusted TAVR valve stent and valve leaflet model in the present application, Figure 2 (b) in the figure is a schematic diagram of the traditional TAVR valve stent based on CT extraction. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further explained and described in combination with the drawings.

[0027] As Figure 1The application provides a fluid-structure coupling numerical simulation method based on an intervention aortic valve, and specifically comprises the following steps:

[0028] Step 1: Dual-source enhanced CT and heart ultrasound are performed on a patient after TAVR, and dual-source enhanced CT files and heart ultrasound files are exported in Dicom format; specifically, the dual-source enhanced CT of the heart is controlled by electrocardiogram gating, the sequence is split every 10% of the cardiac cycle, the best systolic and diastolic sequences are determined, and the split sequence is exported as a dual-source enhanced CT file in Dicom format; the heart ultrasound is simulated by connecting the electrocardiogram leads for 3-5 consecutive cardiac cycles, two-dimensional and three-dimensional motion images and Doppler aortic valve forward blood flow spectrum of the aortic valve are collected, and the heart ultrasound file is exported in Dicom format.

[0029] Step 2: The dual-source enhanced CT file exported in Dicom format is imported into Mimics software, the left ventricle of the heart, the aortic sinus and the ascending aorta are reconstructed, and the valve stent and the artificial valve leaflet of TAVR are reconstructed, the stl file is exported to reconstruct the stent structure of the TAVR valve, a standardized model is obtained, distortion and subsequent problems caused by directly using CT to extract the model are avoided, relevant parameters can be quickly and massively copied, and repeated mesh drawing and the like can be avoided, the workload is greatly reduced, the fluid-structure coupling calculation amount is reduced, the efficiency is improved, and subsequently, computer automatic extraction and matching of the stent mesh intersection of the relevant intervention valve can be adopted, full-automatic CT parameter extraction-matching-fluid-structure coupling is achieved, and clinical popularization and commercial use in the future are expected.

[0030] Step 3: The Mimics software is used to calculate the cardiac left ventricular volume of each sequence of the reconstructed left ventricle of the heart, the aortic sinus and the ascending aorta in step 2, the cardiac left ventricular volume difference between two sequences of adjacent 10% of the cardiac cycle after the left ventricle of the heart is reconstructed and the heart rate when the dual-source enhanced CT is sampled are calculated, and a curve of the change of the cardiac left ventricular volume with time is drawn, so that the actual left ventricular volume and pressure change of the patient are truly reflected, and the simulation result is more in line with the actual situation; specifically, the drawing process of the curve of the change of the cardiac left ventricular volume with time is as follows: the three-dimensional model of the cardiac left ventricle of each sequence is extracted and the volume is calculated, the volume parameter V LV (t) and the corresponding time point t, the time point t is taken as the abscissa, the volume parameter V LV (t) is taken as the ordinate, and the curve of the change of the cardiac left ventricular volume with time is drawn, the volume change rate R of the curve of the change of the cardiac left ventricular volume with time is V LV (t(X+1))-V LV(t(X)) / (t(X+1)-t(X)), wherein t(X) is the corresponding sequence time, t(X+1) is the time at which the next sequence is located, V LV (t(X)) is the left ventricular volume at the corresponding time point t(X), V LV (t(X+1)) is the left ventricular volume at the corresponding time point t(X+1).

[0031] Step 4, a stent and leaflet model of the TAVR valve is established according to the stent data of the TAVR valve measured in vitro by using the Solidworks software; the stent data of the TAVR valve in the application includes: stent wire diameter, stent height, spatial coordinates of all metal intersection points of the stent, cross-sectional diameters of multiple layers of the stent, and spatial coordinates of all suture points of the stent leaflet and the stent structure.

[0032] Step 5, the stent structure of the CT reconstructed TAVR valve in step 2 exported in the stl file is imported into the stent and leaflet model of the TAVR valve established in step 4, and the positions of the corresponding points on the stent and leaflet model of the TAVR valve are adjusted according to the positions of each point on the CT reconstructed stent structure of the TAVR valve, so that the adjusted stent and leaflet model of the TAVR valve are completely coincided with the CT reconstructed stent structure of the TAVR valve, avoiding distortion of the stent and valve model extraction, avoiding repeated grid drawing, helping grid optimization, and greatly reducing the calculation amount of computer fluid-solid coupling.

[0033] Step 6, the adjusted stent and leaflet model of the TAVR valve is meshed, the curve of the left ventricular volume change with time change drawn in step 3 is taken as an inlet condition in the systole, and the central chamber and aortic pressure change curve in the database is taken as an inlet condition in the diastole, fluid parameters determined according to the blood test results of the patient are used for fluid-solid coupling simulation, and simulation results of the opening and closing shape of the valve and the flow velocity spectrum of the valve blood flow are obtained.

[0034] Step 7, the simulation results are corrected by using the heart ultrasound file exported in the Dicom format in step 1 to obtain accurate fluid-solid coupling simulation results of the TAVR valve; specifically, the valve opening shape, area and flow velocity pressure difference of the intervention valve measured from the patient in the heart ultrasound file exported in the Dicom format are taken as a reference to correct the simulation results, so as to obtain accurate fluid-solid coupling simulation results of the TAVR valve, by using the data of the patient himself, the situation is closer to the real situation, the calibration is more accurate and reliable, and the time and economic cost of in vitro calibration are saved, and the reliability of the correction is improved by using the heart ultrasound data of the patient himself as the correction parameter.

[0035] As Figure 2Figure 2 is a comparison diagram of the stent and leaflet model of the TAVR valve adjusted in the application and the traditional CT extraction-based TAVR valve stent, wherein, Figure 2 (b) in Figure 2 is a schematic diagram of the traditional CT extraction-based TAVR valve stent, it can be seen that the CT extraction-based leaflet is very rough, irregular and locally incomplete, which seriously affects the subsequent fluid-structure coupling process, in order to use this model for fluid-structure coupling, a large amount of post-processing is inevitably carried out, and the post-processed model must be artificially reduced and added with local structures, causing serious distortion; Figure 2 (a) in Figure 2 is a schematic diagram of the stent and leaflet model of the TAVR valve adjusted in the application, it can be seen that the stent and leaflet model of the TAVR valve obtained by the application has no artifact distortion and small workload of drawing grid in later stage, which greatly reduces the operation difficulty and workload in later computer simulation calculation, and has practical application and commercial promotion potential for the possibility of subsequent precise full-automatic extraction image-matching-fluid-structure coupling calculation.

[0036] In one of the technical solutions of the application, a computer readable storage medium is provided, which stores a computer program, and the computer program causes a computer to execute the fluid-structure coupling numerical simulation method based on an interventional aortic valve.

[0037] In another technical solution of the application, an electronic device is also provided, which includes a memory, a processor and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the fluid-structure coupling numerical simulation method based on an interventional aortic valve is realized.

[0038] In the embodiments disclosed in the application, the computer storage medium can be a tangible medium, which can contain or store programs for use by or in conjunction with an instruction execution system, device or apparatus. The computer storage medium can include but is not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatus, or any suitable combination of the above. More specific examples of the computer storage medium can include one or more wires, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0039] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software manner depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0040] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall be considered as the protection scope of the present application.

Claims

1. A fluid-structure interaction numerical simulation method based on an interventional aortic valve, characterized in that, Specifically comprising the following steps: Step 1, respectively, for patients after TAVR heart dual-source enhanced CT and cardiac ultrasound, export heart dual-source enhanced CT file and cardiac ultrasound file in Dicom format; Step 2, the Dicom format exported heart dual-source enhanced CT file is imported into Mimics software, reconstructs the left ventricle, aortic sinus and ascending aorta, and reconstructs the valve stent and artificial valve leaflet of TAVR, and exports the CT reconstructed TAVR valve stent structure in stl file; Step 3, using Mimics software to calculate the volume of each sequence of the left ventricle of the heart, according to the difference of the left ventricular volume between the adjacent 10% of the heart cycle after the reconstruction of the left ventricle of the heart and the heart rate at the time of sampling of the heart dual-source enhanced CT, the curve of the left ventricular volume changing with time is drawn; Step 4, according to the data of the stent of the TAVR valve measured in vitro, the stent and the valve leaflet model of the TAVR valve are established by using the Solidworks software; Step 5, the CT reconstructed TAVR valve stent structure exported in stl file in step 2 is imported into the TAVR valve stent and valve leaflet model established in step 4, and the position of the corresponding point on the TAVR valve stent and valve leaflet model is adjusted according to the position of each point on the CT reconstructed TAVR valve stent structure, so that the adjusted TAVR valve stent and valve leaflet model are completely coincided with the CT reconstructed TAVR valve stent structure; Step 6, the adjusted TAVR valve stent and valve leaflet model are meshed, the systolic period is taken as the inlet condition of the curve of the left ventricular volume changing with time drawn in step 3, the diastolic period is taken as the inlet condition of the database heart chamber and aortic pressure change curve, and the fluid parameters determined according to the blood test results of the patient are used for fluid-solid coupling simulation to obtain the simulation results of the opening and closing shape of the valve and the flow velocity spectrum of the blood flow of the valve; Step 7, using the Dicom format exported heart ultrasound file in step 1 to correct the simulation results, the accurate fluid-solid coupling simulation results of the TAVR valve are obtained.

2. The fluid-structure interaction numerical simulation method based on an interventional aortic valve according to claim 1, characterized in that, The heart dual-source enhanced CT is controlled by electrocardiogram, each 10% of the heart cycle is split into sequences, the best systolic period and the best diastolic period sequences are determined, and the split sequences are exported as heart dual-source enhanced CT file in Dicom format.

3. The fluid-structure interaction numerical simulation method based on an interventional aortic valve according to claim 1, characterized in that, The heart ultrasound is connected to the simulated lead of electrocardiogram for 3-5 consecutive heart cycles, the aortic valve two-dimensional and three-dimensional motion images and Doppler aortic valve forward blood flow spectrum are collected, and the heart ultrasound file is exported in Dicom format.

4. The fluid-structure interaction numerical simulation method based on an interventional aortic valve according to claim 1, characterized in that, The process of drawing the curve of left ventricular volume change over time is: extracting the left ventricular three-dimensional model of each sequence and calculating the volume, and obtaining the volume parameter V LV (t) and the corresponding time point t, taking the time point t as the abscissa, and taking the volume parameter V LV (t) as the ordinate to draw the curve of left ventricular volume change over time, the rate of volume change R of the curve of left ventricular volume change over time is R= (V LV (t(X+1))-V LV (t(X)) ) / (t(X+1)-t(X)), wherein t(X) is the corresponding sequence time, t(X+1) is the time at which the next sequence is located, V LV (t(X)) is the left ventricular volume at the corresponding time point t(X), and V LV (t(X+1)) is the left ventricular volume at the corresponding time point t(X+1).

5. The fluid-structure interaction numerical simulation method based on an interventional aortic valve according to claim 1, characterized in that, The stent data of the TAVR valve includes: stent wire diameter, stent height, spatial coordinates of all metal intersection points of the stent, cross-sectional diameter of multiple layers of the stent, and spatial coordinates of all suture points of the stent valve leaflet and the stent structure.

6. The fluid-structure interaction numerical simulation method based on an interventional aortic valve according to claim 1, characterized in that, The specific process of step 7 is: taking the valve opening shape, area and flow velocity pressure difference of the interventional valve measured from the patient in the Dicom format exported heart ultrasound file as reference, correcting the simulation results, so as to obtain the accurate fluid-solid coupling simulation results of the TAVR valve.

7. A computer readable storage medium storing a computer program, characterized in that, The computer program enables a computer to perform the fluid-structure coupling numerical simulation method based on an interventional aortic valve as claimed in any one of claims 1-6.

8. An electronic device, comprising: Comprise: A memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the fluid-structure coupling numerical simulation method based on an interventional aortic valve as claimed in any one of claims 1-6 when executing the computer program.

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