Method, system, device and medium for predicting crack propagation of artificial valve leaflet

Abstract

The present invention proposes a method, system, device and medium for predicting crack propagation of an artificial valve leaflet. The method includes obtaining the stress load spectrum and the initial crack shape and length at any point on the surface of the artificial valve leaflet during several cardiac cycles; obtaining the number of load sequence segments of the stress load spectrum during the cardiac cycle after the load trend tends to be stable, and the maximum stress value and minimum stress value of each load sequence; calculating the maximum stress and minimum stress around the crack based on the maximum stress value and minimum stress value of each load sequence, and calculating the crack propagation tear length generated by each load sequence, and then obtaining the single total tear length generated by a single cardiac cycle based on the length of the initial crack, and calculating the total number of cardiac cycles required based on the total crack length when the artificial valve leaflet reaches damage. The present invention can predict the damage size of the artificial valve leaflet more accurately, thereby assisting in diagnosis and treatment and assisting in the optimal design of the prosthetic valve.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial valve leaflets, and in particular relates to a method, system, equipment and medium for predicting crack propagation of artificial valve leaflets. Background Art

[0002] Valves and leaflets play a vital role in the human circulatory system. When a valve becomes diseased, minimally invasive interventional surgery becomes an effective, safe, and less harmful treatment. Through this surgery, a prosthetic valve can be implanted to replace and substitute for the diseased valve. The artificial leaflets of these prosthetic valves are usually made of animal pericardium or polymer materials. Although they have excellent performance, they have a certain fatigue life limit. According to FDA regulations, the fatigue life of artificial leaflets should be greater than 200 million times, which is approximately equivalent to a service life of ten years, thereby ensuring that patients can benefit long-term after undergoing surgery.

[0003] When a prosthetic valve is implanted in the human body, cracks will appear when the number of times the artificial leaflets are opened and closed reaches the fatigue life limit. Currently, the evaluation of the overall fatigue life of the prosthetic valve is completed through in vitro accelerated fatigue testing (the leaflets open and close 10 times or more per second). This experiment can obtain the overall fatigue life of the valve under idealized working conditions and evaluate whether the valve as a whole meets regulatory standards. The fatigue test observes the leaflets to see if they are damaged by the naked eye, but in the experiment, the cracks generated when the leaflets reach the fatigue limit are extremely small and cannot be detected by the naked eye. When significant cracks are detected by the naked eye, the number of times the leaflets open and close has far exceeded the fatigue life limit.

[0004] Existing technologies are unable to effectively predict the crack propagation rate and crack trend of artificial valve leaflets. Especially after a prosthetic valve is implanted in the human body, when the artificial valve leaflet reaches its fatigue life limit and ruptures, it is clinically impossible to predict the rate at which the crack will continue to propagate. Summary of the Invention

[0005] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a method, system, equipment and medium for predicting crack propagation of artificial valve leaflets, so as to solve the problem that the prior art is unable to better predict the crack propagation rate, crack trend, etc. of artificial valve leaflets, especially when the prosthetic valve is implanted in the human body, when the artificial valve leaflet reaches the fatigue life limit and ruptures, the clinical practice is unable to predict the speed at which the crack will continue to propagate.

[0006] To achieve the above and other related objectives, the present invention provides a method for predicting crack propagation of an artificial valve leaflet, comprising:

[0007] Obtain the stress load spectrum, initial crack shape and length at any point on the artificial valve leaflet surface during several cardiac cycles;

[0008] Obtaining a stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable, and obtaining the number of load sequence segments, the maximum stress value, and the minimum stress value of each load sequence segment of the stress load spectrum;

[0009] The maximum stress and minimum stress around the crack are calculated based on the maximum stress and minimum stress values ​​of each load sequence;

[0010] Calculate the crack propagation and tearing length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0011] The total tear length generated by a single cardiac cycle is obtained based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0012] The total number of cardiac cycles required is calculated based on the total crack length of the artificial valve leaflet when it reaches damage and the total single tear length.

[0013] In one embodiment of the present invention, the step of obtaining the stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable, and obtaining the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment includes:

[0014] Obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable;

[0015] Simplifying the stress load spectrum;

[0016] According to the simplified stress load spectrum, the number of load sequence segments, the maximum stress value and the minimum stress value of each load sequence are obtained.

[0017] In one embodiment of the present invention, the calculating and obtaining the maximum stress and minimum stress around the crack according to the maximum stress value and the minimum stress value of each load sequence includes:

[0018] The maximum stress value S max and the minimum stress value S min Substitute into the formula respectively The maximum stress σ around the crack is calculated separately. max and minimum stress σ min ;

[0019] Where E is the elastic modulus of the artificial valve leaflet material; e is the working hardening index of the artificial valve leaflet material; K t is the stress concentration factor.

[0020] In one embodiment of the present invention, the calculating and obtaining the maximum stress and minimum stress around the crack according to the maximum stress value and the minimum stress value of each load sequence includes:

[0021] The maximum stress value S max and the minimum stress value S min Substitute into the formula respectively The maximum stress σ around the crack is calculated separately. max and minimum stress σ min ;

[0022] Where E is the elastic modulus of the artificial valve leaflet material; e is the working hardening index of the artificial valve leaflet material; K t is the stress concentration factor.

[0023] In one embodiment of the present invention, when the initial crack shape is elliptical, the stress concentration factor K t Calculated by the following formula:

[0024] Where L is the major axis of the initial crack, and q is the minor axis of the initial crack.

[0025] In one embodiment of the present invention, when the initial crack shape is elliptical, the stress concentration factor K t Calculated by the following formula:

[0026] Where q is the minor axis of the initial crack, and r is the fillet radius of the initial crack.

[0027] In one embodiment of the present invention, the step of calculating the crack propagation tear length generated by each load sequence based on the maximum stress and the minimum stress around the crack comprises:

[0028] The maximum stress σ of the nth load sequence max and minimum stress σ min Substitute into the formula In order to calculate the crack extension and tearing length generated by the nth load sequence,

[0029]

[0030] Wherein, C is the crack growth rate of the artificial valve leaflet material; m is the crack growth index of the artificial valve leaflet material; α is the crack growth length, and H is the length of the initial crack.

[0031] The present invention also provides a crack propagation prediction system for an artificial valve leaflet, comprising:

[0032] A data acquisition module is used to obtain the stress load spectrum and initial crack shape and length of any point on the surface of the artificial valve leaflet during several cardiac cycles;

[0033] A load sequence acquisition module is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment;

[0034] The stress calculation module is used to calculate the maximum stress and minimum stress around the crack based on the maximum stress value and minimum stress value of each load sequence;

[0035] A single-segment tear length calculation module is used to calculate the crack propagation tear length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0036] A single-cycle tear length calculation module is used to obtain the total tear length generated by a single cardiac cycle based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0037] The crack extension calculation module is used to calculate the total number of cardiac cycles required based on the total crack length of the artificial valve leaflet when it reaches damage and the single total tear length.

[0038] The present invention also proposes an electronic device comprising a processor, a memory and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute a computer program stored in the memory to implement a crack propagation prediction method for an artificial valve leaflet as described in any one of the above embodiments.

[0039] The present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program is used to enable a computer to execute the method for predicting crack propagation of an artificial valve leaflet as described in any one of the above embodiments.

[0040] The present invention proposes a method, system, equipment and medium for predicting crack propagation of artificial valve leaflets, which can predict and calculate in a short period of time the speed and angle of continued tearing of the damaged cracks in the prosthetic valve during in vitro experiments or implantation in the body after the artificial valve leaflet reaches its service life. Then, by formulating standards for the acceptable degree of cracks in the artificial valve leaflet, the time during which the artificial valve leaflet can continue to work normally can be predicted, or the maximum time at which the artificial valve leaflet requires secondary surgical intervention after reaching its service life can be evaluated, thereby assisting in diagnosis and treatment. In addition, in in vitro accelerated fatigue experiments during the research and development and design process of prosthetic valves, when the damage of the artificial valve leaflet is not timely and accurately observed, a more accurate artificial valve leaflet damage size can be obtained based on the crack propagation prediction method of the artificial valve leaflet described in the present invention, thereby assisting in the optimized design of the prosthetic valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 Schematic diagram of a flow chart of a method for predicting crack propagation of an artificial valve leaflet in one embodiment of the present invention.

[0043] Figure 2 Schematic diagram of obtaining the stress load spectrum of the integral points on the surface of the artificial valve leaflet during 5 cardiac cycles in one embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram of extracting the stress load spectrum of the last cardiac cycle in one embodiment of the present invention.

[0045] Figure 4 Schematic diagram of a simplified stress load spectrum during the last cardiac cycle in one embodiment of the present invention.

[0046] Figure 5 Schematic diagram of a crack in an artificial valve leaflet in one embodiment of the present invention.

[0047] Figure 6 This is a structural block diagram of a crack propagation prediction system for an artificial valve leaflet in one embodiment of the present invention.

[0048] Figure 7 This is a structural block diagram of a crack propagation prediction and calculation device for an artificial valve leaflet in one embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0050] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0051] See also Figure 1 As shown, in this embodiment, in view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method, system, device and medium for predicting crack propagation of artificial valve leaflets, so as to solve the problem that the prior art cannot make a good prediction of the crack propagation rate and crack trend of artificial valve leaflets, especially when the prosthetic valve is implanted in the human body and the artificial valve leaflets reach the fatigue life limit and rupture, the clinical cannot predict the speed at which the cracks continue to propagate. Specifically, the method for predicting crack propagation of artificial valve leaflets includes:

[0052] S1. Obtain the stress load spectrum and initial crack shape and length of any point on the artificial valve leaflet surface during several cardiac cycles;

[0053] S2. Obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment.

[0054] S3. Calculate the maximum stress and minimum stress around the crack based on the maximum stress value and minimum stress value of each load sequence;

[0055] S4. Calculating the crack propagation and tearing length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0056] S5. Obtaining a single total tear length generated by a single cardiac cycle based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0057] S6. Calculate the total number of cardiac cycles required based on the total crack length of the artificial valve leaflet when it reaches damage and the total single tear length.

[0058] In step S1 , for example, bidirectional fluid-solid coupling finite element simulation can be used to obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point during several cardiac cycles.

[0059] It is understandable that in each cardiac cycle, the artificial valve leaflet completes a cyclical movement of opening and closing due to the flow field force. However, in one movement cycle, any point on the surface of the artificial valve leaflet is subjected to several changing stress loads. All the stress loads on the artificial valve leaflet in one movement cycle are the stress load spectrum of the point. For example, Figure 2As shown in the figure, the stress load spectrum of any point on the surface of the artificial valve leaflet within 4 cardiac cycles is obtained. Since the multi-field coupling calculation is affected by the calculation value error generated when it is first started, the stress load spectrum of this point in the first cardiac cycle has no periodic pattern, but the calculation error is gradually eliminated in the 2-4 cardiac cycles, the fluid dynamics representation of each cardiac cycle tends to be consistent, and the stress load spectrum shows a periodic pattern.

[0060] It is understood that, based on knowledge of material mechanics and fracture mechanics, points with large maximum stress values ​​are fatigue failure risk points, meaning they have a poor fatigue life and are more susceptible to tearing and breakage. Therefore, the points selected should preferably be those with large maximum stress values. In some other embodiments, in addition to points with large maximum stress values, any other points of interest can be used as stress load spectrum extraction points.

[0061] In step S2, the steps of obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment include:

[0062] S21. Obtaining a stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable;

[0063] S22, simplifying the stress load spectrum;

[0064] S23. Obtain the number of load sequence segments, the maximum stress value, and the minimum stress value of each load sequence segment according to the simplified stress load spectrum.

[0065] It is understandable that the rain flow counting method can be used to extract all sub-cycles in the load spectrum and record the number n of identical sub-cycles. The rain flow counting method refers to rotating the stress-time history data record of the stress load spectrum by 90°, with the time coordinate axis pointing vertically downward. The data record is like a series of roofs, and rainwater flows down along the roofs, so it is called the rain flow counting method. The main function of the rain flow counting method is to simplify the measured load history into several load cycles for fatigue life estimation and preparation of fatigue test load spectra. It is based on the two-parameter method, taking into account the two variables of dynamic strength (amplitude) and static strength (mean), and conforms to the inherent characteristics of the fatigue load itself. Its basic counting principle is:

[0066] The rain flow flows down the slope from the inner side of the peak position of the load time history;

[0067] The rain flow starts from a certain peak point and stops when it encounters a peak larger than its starting peak.

[0068] When a rain stream meets a rain stream flowing down from above, it must stop flowing;

[0069] Take out all the full cycles and write down the amplitude of each cycle;

[0070] The divergent-convergent load time history remaining after the first stage counting is equivalent to a convergent-divergent load time history, and the second stage rainflow counting is performed. The total number of counting cycles is equal to the sum of the counting cycles of the two counting stages.

[0071] In this embodiment, the stress load spectrum of the last (4th) cardiac cycle of the point is extracted. For the last cardiac cycle, please refer to Figure 3 As shown in the figure, the number of load sequence segments of the stress load spectrum and the maximum stress value S of each load sequence are obtained by the rain flow counting method. max , the minimum stress value S of each load sequence min Of course, if the number of cardiac cycles calculated by multi-field coupling is greater (for example, calculation up to the 10th cardiac cycle), the stress load spectrum of the points within the 10th cardiac cycle should be extracted.

[0072] It is understandable that in order to reduce the amount of rain flow counting calculations, the stress load spectrum can also be simplified, see Figure 4 As shown, Figure 4 Yes Figure 3 The stress load spectrum of the last cardiac cycle is simplified by considering the similar peak values ​​in the load spectrum as equal and taking them as the average value, thereby simplifying the load spectrum and reducing the amount of calculation.

[0073] It can be understood that the multi-field coupling is a surface stress calculation based on a complete and undamaged three-dimensional model of the artificial valve leaflet. Combining the knowledge of fatigue mechanics and the tear shape set above, the Glinka criterion based on strain energy density theory is used to calculate the maximum stress value and the minimum stress value around the crack. The Glinka criterion is based on the assumption that as long as the plastic zone at the crack is surrounded by an elastic field, the strain energy density at the notch root of the linear elastic notch behavior and the elastic-plastic notch behavior is almost the same. The multi-field coupling stress calculation and tear setting of the artificial valve leaflet described in the present invention conform to the basic assumptions of the Glinka criterion. Therefore, in step S3, the calculation of the maximum stress value and the minimum stress value of each load sequence to obtain the maximum stress and minimum stress around the crack includes:

[0074] The maximum stress value S max and the minimum stress value S min Substitute them into the Glinka criterion to predict the stress around the crack to calculate the maximum stress σ around the crack max and minimum stress σ min , the Glinka criterion predicts the stress around the crack as follows: Where E is the elastic modulus of the artificial valve leaflet material, which is an inherent material constant and can be obtained through mechanical experiments on artificial valve leaflet materials; e is the working hardening index of the artificial valve leaflet material, which is an inherent material constant and can be obtained through mechanical experiments on artificial valve leaflet materials; S is the applied stress, which is the maximum stress value S of each load sequence in the stress load spectrum at that point. max Or minimum stress value S min The maximum stress value S of the i-th load sequence is recorded as imax Or minimum stress value S imin ,For example, Figure 4 In the embodiment, there are two load sequences, the maximum stress value S in the first segment is 1max is 1Mpa, the minimum stress value S 1min is 0.2Mpa; the maximum stress value S in the second section 2max is 1Mpa, the minimum stress value S 2min 0.3Mpa. ;K t is the stress concentration factor, which is only related to the structure and shape of the crack and has nothing to do with the material. Figure 5 As shown in the examples, the K of the elliptical crack t The calculation formula is:

[0075] Wherein, L is the major axis of the initial crack, and q is the minor axis of the initial crack;

[0076] Of course, in some other embodiments, the stress concentration factor K t It can also be calculated by the following formula:

[0077] Where q is the minor axis of the initial crack, and r is the fillet radius of the initial crack. Of course, when the initial crack has other shapes, such as a rectangular or diamond-shaped crack, the Kt value is calculated accordingly.

[0078] It is also understood that in some other embodiments, the maximum stress value and the minimum stress value around the crack can be calculated by using mechanical principles such as the Neuber criterion or the linear criterion. Specifically, the maximum stress and the minimum stress around the crack are calculated based on the maximum stress value and the minimum stress value of each load sequence, including:

[0079] The maximum stress value S max and S min Substitute into the Neuber criterion formula respectively The maximum stress σ around the crack is calculated separately. max and minimum stress σ min .

[0080] See also Figure 1As shown, in step S4, the crack propagation tearing length generated by each load sequence is calculated based on the maximum stress and minimum stress around the crack, including:

[0081] The maximum stress σ of the nth load sequence max and minimum stress σ min Substitute into the formula In order to calculate the crack extension and tearing length generated by the nth load sequence,

[0082]

[0083] Wherein, C is the crack growth rate of the artificial valve leaflet material, which is an inherent material constant and can be obtained by fitting and measuring the cyclic tensile mechanical experiment of the artificial valve leaflet material sample; m is the crack growth index of the artificial valve leaflet material, which is an inherent material constant and can be obtained by fitting and measuring the cyclic tensile mechanical experiment of the artificial valve leaflet material sample; α is the crack growth length; and H is the length of the initial crack.

[0084] See also Figure 1 As shown, in step S5, the method of obtaining the total tear length generated by a single cardiac cycle based on the length of the initial crack and the crack propagation tear length of each load sequence specifically includes: calculating the propagation tear length of the crack in each direction under n load sequences according to the superposition principle. The calculation formula of the superposition principle is: Where α0 is the initial crack length. If the tear length in the major axis direction is calculated, the L value is substituted. If the tear length in the minor axis direction is calculated, the q value is substituted.

[0085] See also Figure 1 As shown, in step S6, assuming that the maximum crack length is less than Y mm and does not affect the normal function of the prosthetic valve, the life of the prosthetic valve leaflet is calculated by calculating the number of cycles from the time the crack appears at the fatigue life of the prosthetic valve leaflet to the time the crack propagates to Y mm. That is, the total number of cardiac cycles is calculated based on the total crack length at the time the prosthetic valve leaflet reaches damage and the total single tear length. The total number of cardiac cycles is the maximum life of the prosthetic valve leaflet from crack initiation to complete failure. It is understood that the total time required from crack initiation to crack propagation to Y mm, calculated based on the valve leaflet opening and closing speed or heart rate in an in vitro accelerated test, can also be used as the maximum life of the prosthetic valve leaflet from crack initiation to complete failure.

[0086] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0087] See also Figure 6As shown, the present invention provides a crack propagation prediction system for an artificial valve leaflet, which corresponds to the crack propagation prediction method for an artificial valve leaflet in the above embodiment. Figure 6 This is a block diagram of the structure of a crack propagation prediction system for an artificial valve leaflet proposed in the present invention. The crack propagation prediction system 100 for an artificial valve leaflet includes a data acquisition module 10, a load sequence acquisition module 20, a stress calculation module 30, a single-segment tear length calculation module 40, a single-cycle tear length calculation module 50, and a crack propagation calculation module 60. The functional modules are described in detail as follows:

[0088] The data acquisition module 10 is used to obtain the stress load spectrum and initial crack shape and length of any point on the surface of the artificial valve leaflet during several cardiac cycles;

[0089] The load sequence acquisition module 20 is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment;

[0090] The stress calculation module 30 is used to calculate the maximum stress and minimum stress around the crack according to the maximum stress value and minimum stress value of each load sequence;

[0091] The single-segment tear length calculation module 40 is used to calculate the crack propagation tear length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0092] The single-cycle tear length calculation module 50 is used to obtain the single total tear length generated by a single cardiac cycle based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0093] The crack extension calculation module 60 is used to calculate the required total number of cardiac cycles based on the total crack length when the artificial valve leaflet reaches damage and the single total tear length.

[0094] For the specific definition of the crack propagation prediction system for artificial valve leaflets, please refer to the definition of the crack propagation prediction method for artificial valve leaflets above, which will not be repeated here. The various modules in the above-mentioned crack propagation prediction system for artificial valve leaflets can be implemented in whole or in part by software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0095] See also Figure 7As shown, the present invention also proposes a crack propagation prediction calculation device for artificial valve leaflets, which can evaluate and calculate the service life of artificial valve leaflets of prosthetic valves that require long-term in vitro fatigue testing, or evaluate and calculate the service life of artificial valve leaflets of prosthetic valves implanted in the body through the input of prosthetic valve product data, in vitro experimental data and clinical data. Specifically, the data intersection module 101, the three-dimensional modeling module 102, the virtual experiment & virtual surgery module 103, the multi-field coupling calculation module 104, the fatigue life evaluation module 105 and the human-computer interaction module 106. The functional modules are described in detail as follows:

[0096] The data exchange module 101 is used to collect and store prosthetic valve product data, in vitro experimental data and clinical data, and transmit these data to the three-dimensional modeling module 102 and the human-computer interaction module 106.

[0097] A prosthetic valve typically consists of a metal stent, artificial leaflets, and a skirt. The metal stent is often made of metals such as cobalt-chromium alloy and nickel-titanium alloy. The artificial leaflets can be made from biological tissues such as porcine or bovine pericardium, or from polymers such as expanded polytetrafluoroethylene (EPTFE) and polyethylene terephthalate (PET), modeled after the natural human leaflets. The skirt, often made of polymers such as expanded polytetrafluoroethylene (EPTFE) and polyethylene terephthalate (PET), provides a seal.

[0098] The valve product data described in the present invention includes the dimensional and structural parameters of the metal stent, prosthetic valve leaflets, and skirt (e.g., the diameter of the metal stent and the height of the prosthetic valve leaflets), as well as material parameters (e.g., the elastic modulus of the metal stent material and the fatigue life curve of the prosthetic valve leaflet material). This data can be input into product parameters based on the actual structural design of the prosthetic valve in use, ensuring the integrity of these dimensional and structural parameters and material parameters.

[0099] In the in vitro bionic circulation test of the prosthetic valve, the prosthetic valve is loaded and fixed in a containing structure. Liquid flows in from the inflow end and then flows out from the outflow end to simulate the flow of blood in the body, causing the artificial valve leaflets to open and close.

[0100] The in vitro experimental data described in the present invention refers to the internal space dimensional parameters of the prosthetic valve, the liquid pressure parameters applied at the inflow end, and the liquid parameters applied at the outflow end during the in vitro bionic circulation test of the prosthetic valve. The dimensional parameters of the containment structure are used to define the area where the liquid can flow during the experiment, and the pressure parameters at both ends are used as load inputs for the subsequent multi-field coupling calculation. It is understandable that if other structural experimental instruments are used, the dimensional parameters of the containment structure should be input based on the actual situation to ensure the integrity of these dimensional structures.

[0101] In vitro experimental data can also include experimental result data, such as liquid flow rate, liquid pressure, etc., which can be used as a comparison and verification for the subsequent multi-field coupling calculation results.

[0102] The clinical data described in the present invention includes multimodal valve imaging data, including but not limited to valve ultrasound imaging data, valve CTA imaging data, valve magnetic resonance imaging data, and bilateral valve pressure. The clinical data can be divided into preoperative data and postoperative data. Preoperative data can be used as parameter input for later 3D model reconstruction and virtual surgery boundary conditions, while postoperative data can be used for comparison and verification of later virtual surgery and multi-field coupling calculation results.

[0103] The clinical data described in the present invention only takes the aortic valve as an example. If other valves are used (such as the mitral valve, tricuspid valve, pulmonary valve, lower limb venous valve, etc.), the multimodal imaging data of the corresponding parts should be input according to the actual situation, and ensure that the three-dimensional modeling of the native valve tissue and its surrounding tissues can be completed through one influencing data.

[0104] The three-dimensional modeling module 102 uses the prosthetic valve product data, in vitro experimental data and clinical data in the data intersection module 101 to construct a three-dimensional model of the prosthetic valve, a three-dimensional flow field model of the in vitro experiment and a three-dimensional model of the individualized tissue structure, and can communicate with the human-computer interaction module 106 to provide feedback on the construction progress and results of the three-dimensional model.

[0105] Taking the preoperative aortic valve as an example, the 3D modeling module 102 first constructs a rough 3D tissue model directly based on the impact data. The model then smoothes and repairs the rough 3D model, further refining it into a preoperative 3D model suitable for virtual surgery and multi-field coupling calculations. The internal space of this preoperative 3D model then becomes the personalized 3D flow field model.

[0106] The virtual experiment and virtual surgery module 103 can simulate real experimental operations and real surgical operations based on the finite element algorithm, and implant the three-dimensional model of the prosthetic valve product constructed by the three-dimensional modeling module 102 into the containing structure in the in vitro experiment or the preoperative three-dimensional model according to actual experimental operations or actual surgical operations.

[0107] The three-dimensional model of the prosthetic valve product is implanted into the preoperative three-dimensional model through the same compression, gripping, intervention, release, and balloon expansion operations as the actual surgical procedure, thereby completing the virtual surgical process and obtaining a virtual postoperative three-dimensional model (different from the postoperative three-dimensional model obtained based on the impact data in the three-dimensional modeling module 102).

[0108] Implanting the 3D model of the prosthetic valve into the in vitro containment structure completes the virtual experiment implantation process, thereby obtaining a virtual experiment implantation model. The virtual experiment implantation process is similar to the virtual surgical implantation process and will not be described in detail here.

[0109] The multi-field coupling calculation module 104, based on computational fluid dynamics theory, adaptive grid theory, immersed boundary theory, and arbitrary Lagrangian-Euler theory, obtains a virtual experimental implant model or a virtual post-operative three-dimensional model based on the virtual experiment & virtual surgery module 103. The module embeds the aortic vascular constitutive equation inverted based on multimodal imaging data and the leaflet constitutive equation based on uniaxial / biaxial tensile testing and Bayesian inference fitting of the Mooney-Rivlin constitutive equation. The module also embeds the patient's left ventricular and ascending aorta dynamic pressure curves measured by Doppler ultrasound as load inputs and uses the ascending aorta blood flow velocity based on 4D flow as a verification condition. A bidirectional fluid-structure coupling algorithm is used to reconstruct the fluid dynamics and the kinematics of the vessel wall and leaflets. A multi-field coupling calculation model of blood flow, vessel wall, and valve is constructed (i.e., simulating fluid flow and driving the opening and closing motion of the artificial valve leaflets). The module then outputs multiple information, including leaflet morphological parameters, leaflet mechanical function parameters, liquid ejection angle, and liquid flow trend.

[0110] The crack propagation calculation module 105 first obtains the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point based on the multivariate information such as the artificial valve leaflet morphological parameters, the mechanical function parameters of the valve leaflet, and the blood flow trend output by the multi-field coupling calculation module 104, and then calculates the fatigue strength of each load sequence in the stress load spectrum by the rain flow counting method and the Goodman criterion, and then calculates the fatigue life of the point by the superposition principle, and finally completes the calculation of the expected fatigue life of the artificial valve leaflet. It can be understood that the crack propagation calculation module 105 is the same as the crack propagation prediction system of the artificial valve leaflet described in the above embodiment, and corresponds to the crack propagation prediction method of the artificial valve leaflet in the above embodiment.

[0111] See also Figure 1 and Figure 2 As shown, the present application also proposes an electronic device, comprising a processor, a memory, and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute a computer program stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0112] Obtain the stress load spectrum, initial crack shape and length at any point on the artificial valve leaflet surface during several cardiac cycles;

[0113] Obtaining a stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable, and obtaining the number of load sequence segments, the maximum stress value, and the minimum stress value of each load sequence segment of the stress load spectrum;

[0114] The maximum stress and minimum stress around the crack are calculated based on the maximum stress and minimum stress values ​​of each load sequence;

[0115] Calculate the crack propagation and tearing length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0116] The total tear length generated by a single cardiac cycle is obtained based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0117] The total number of cardiac cycles is calculated based on the total crack length of the artificial valve leaflet when it is damaged and the total single tear length. The total number of cardiac cycles is the lifespan of the artificial valve leaflet.

[0118] See also Figure 1 and Figure 2 As shown, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which implements the following steps when the computer program is executed by a processor:

[0119] Obtain the stress load spectrum, initial crack shape and length at any point on the artificial valve leaflet surface during several cardiac cycles;

[0120] Obtaining a stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable, and obtaining the number of load sequence segments, the maximum stress value, and the minimum stress value of each load sequence segment of the stress load spectrum;

[0121] The maximum stress and minimum stress around the crack are calculated based on the maximum stress and minimum stress values ​​of each load sequence;

[0122] Calculate the crack propagation and tearing length generated by each load sequence based on the maximum stress and minimum stress around the crack;

[0123] The total tear length generated by a single cardiac cycle is obtained based on the length of the initial crack and the crack propagation tear length of each load sequence;

[0124] The total number of cardiac cycles is calculated based on the total crack length when the artificial valve leaflet reaches the fatigue life and the single total tear length. The total number of cardiac cycles is the life of the artificial valve leaflet.

[0125] It should be noted that the functions or steps that can be implemented by the computer-readable storage medium or computer device can be found in the aforementioned method embodiments. To avoid repetition, they will not be described one by one here.

[0126] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0127] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0128] The present invention proposes a method, system, equipment and medium for predicting crack expansion of artificial valve leaflets, which can predict and calculate in a short period of time the speed and angle of the continued tearing of the damaged cracks in the prosthetic valve during in vitro experiments or implanted in the body after the artificial valve leaflet reaches its service life. Then, by formulating standards for the acceptable degree of cracks in the artificial valve leaflet, the time during which the artificial valve leaflet can continue to work normally can be predicted, or the maximum time during which the artificial valve leaflet requires secondary surgical intervention after reaching its service life can be evaluated, thereby assisting in diagnosis and treatment. For example, through individualized artificial valve leaflet fatigue life assessment, the service life of the artificial valve leaflet is about 10 years. Through the crack expansion prediction described in the present invention, the time from the generation of tiny cracks to the crack expansion to the maximum acceptable degree is 3 months. Therefore, the patient should receive examination and secondary treatment within at least 3 months 10 years after the operation to avoid life-threatening conditions.

[0129] The present invention proposes a method, system, equipment and medium for predicting crack propagation of artificial valve leaflets. In an in vitro accelerated fatigue test during the research, development and design process of a prosthetic valve, when it is not timely and accurately observed when the artificial valve leaflet is damaged, a more accurate artificial valve leaflet damage size can be obtained based on the crack propagation prediction method of the artificial valve leaflet described in the present invention, thereby assisting in the optimized design of the prosthetic valve. For example, in an in vitro 20-fold accelerated fatigue test, a 10mm crack was observed in the artificial valve leaflet on the 300th day. According to the crack propagation prediction described in the present invention, it takes 2 days for the tiny crack to propagate to a 10mm crack. Therefore, the actual fatigue life of the artificial valve leaflet in this in vitro accelerated fatigue test is (300-2)*20=5960 days, not 300*20=6000 days.

[0130] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

[0131] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A method for predicting crack propagation of an artificial valve leaflet, characterized in that: include: Obtain the stress load spectrum, initial crack shape and length at any point on the artificial valve leaflet surface during several cardiac cycles; Obtaining a stress load spectrum of any cardiac cycle after the load trend during several cardiac cycles becomes stable, and obtaining the number of load sequence segments, the maximum stress value, and the minimum stress value of each load sequence segment of the stress load spectrum; The maximum stress and minimum stress around the crack are calculated based on the maximum stress and minimum stress values ​​of each load sequence; Calculate the crack propagation and tearing length generated by each load sequence based on the maximum stress and minimum stress around the crack; The total tear length generated by a single cardiac cycle is obtained based on the length of the initial crack and the crack propagation tear length of each load sequence; The total number of cardiac cycles required is calculated based on the total crack length of the artificial valve leaflet when it reaches damage and the total single tear length.

2. The method for predicting crack propagation of an artificial valve leaflet according to claim 1, wherein: The steps of obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtaining the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment include: Obtaining the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable; Simplifying the stress load spectrum; According to the simplified stress load spectrum, the number of load sequence segments, the maximum stress value and the minimum stress value of each load sequence are obtained.

3. The method for predicting crack propagation of an artificial valve leaflet according to claim 1, wherein: The calculation of the maximum stress and the minimum stress around the crack according to the maximum stress value and the minimum stress value of each load sequence includes: The maximum stress value S max and the minimum stress value S min Substitute into the formula respectively The maximum stress σ around the crack is calculated separately. max and minimum stress σ min ; Where E is the elastic modulus of the artificial valve leaflet material; e is the working hardening index of the artificial valve leaflet material; K t is the stress concentration factor.

4. The method for predicting crack propagation of an artificial valve leaflet according to claim 1, wherein: The calculation of the maximum stress and the minimum stress around the crack according to the maximum stress value and the minimum stress value of each load sequence includes: The maximum stress value S max and the minimum stress value S min Substitute into the formula respectively The maximum stress σ around the crack is calculated separately. max and minimum stress σ min ; Where E is the elastic modulus of the artificial valve leaflet material; e is the working hardening index of the artificial valve leaflet material; K t is the stress concentration factor.

5. The method for predicting crack propagation of an artificial valve leaflet according to claim 3 or 4, characterized in that: When the initial crack shape is elliptical, the stress concentration factor K t Calculated by the following formula: Where L is the major axis of the initial crack, and q is the minor axis of the initial crack.

6. The method for predicting crack propagation of an artificial valve leaflet according to claim 3 or 4, characterized in that: When the initial crack shape is elliptical, the stress concentration factor K t Calculated by the following formula: Where q is the minor axis of the initial crack, and r is the fillet radius of the initial crack.

7. The method for predicting crack propagation of an artificial valve leaflet according to claim 1, wherein: The method of calculating the crack propagation and tearing length generated by each load sequence according to the maximum stress and minimum stress around the crack includes: The maximum stress σ of the nth load sequence max and minimum stress σ min Substitute into the formula In order to calculate the crack extension and tearing length generated by the nth load sequence, Wherein, C is the crack growth rate of the artificial valve leaflet material; m is the crack growth index of the artificial valve leaflet material; α is the crack growth length, and H is the length of the initial crack.

8. A system for evaluating the lifespan of an artificial valve leaflet, characterized in that: include: A data acquisition module is used to obtain the stress load spectrum and initial crack shape and length of any point on the surface of the artificial valve leaflet during several cardiac cycles; A load sequence acquisition module is used to obtain the stress load spectrum of any cardiac cycle after the load trend in several cardiac cycles tends to be stable, and obtain the number of load sequence segments of the stress load spectrum, the maximum stress value and the minimum stress value of each load sequence segment; The stress calculation module is used to calculate the maximum stress and minimum stress around the crack based on the maximum stress value and minimum stress value of each load sequence; A single-segment tear length calculation module is used to calculate the crack propagation tear length generated by each load sequence based on the maximum stress and minimum stress around the crack; A single-cycle tear length calculation module is used to obtain the total tear length generated by a single cardiac cycle based on the length of the initial crack and the crack propagation tear length of each load sequence; The crack extension calculation module is used to calculate the total number of cardiac cycles required based on the total crack length of the artificial valve leaflet when it reaches damage and the single total tear length.

9. An electronic device, characterized in that: It comprises a processor, a memory and a communication bus; the communication bus is used to connect the processor and the memory; the processor is used to execute the computer program stored in the memory to implement the crack propagation prediction method of the artificial valve leaflet as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and the computer program is used to enable a computer to execute the crack propagation prediction method of an artificial valve leaflet as described in any one of claims 1 to 7.

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