A method, system, device and medium for evaluating fatigue life of a prosthetic leaflet

Abstract

The application provides a kind of artificial valve fatigue life evaluation method, system, equipment and medium, method includes: obtaining the stress load spectrum of artificial valve surface fatigue failure risk point in several cardiac cycles;Obtain the load order segment number of the stress load spectrum of any cardiac cycle after the load trend tends to be stable, the alternating stress, average stress and cycle number of each load order segment;Calculate the fatigue failure cycle number of the artificial valve material standard sample corresponding to each load order segment;The ratio of cycle number and fatigue failure cycle number under each load order segment is calculated to obtain the fatigue damage under the load order segment;The sum of fatigue damage under all load orders is obtained, and its reciprocal is the expected fatigue life.The application has the advantages of short time consumption, low cost, low difficulty, high accuracy, high precision and less limitation.

Description

Technical Field

[0001] This invention belongs to the field of artificial leaflet technology, and specifically relates to a method, system, equipment and medium for evaluating the fatigue life of artificial leaflets. Background Technology

[0002] Valves and leaflets play a vital role in the human circulatory system. When valves become diseased, minimally invasive interventional surgery becomes an effective, safe treatment method with fewer side effects. This surgery allows for the implantation of prosthetic valves to replace and replace the diseased valve. The artificial leaflets of these prosthetic valves are typically made from animal pericardium or polymer materials. While they possess excellent performance, they have a limited fatigue life. According to FDA regulations, the fatigue life of artificial valve leaflets should exceed 200 million cycles, roughly equivalent to a ten-year lifespan, thus ensuring long-term benefit for patients after surgery.

[0003] Currently, the overall fatigue life of prosthetic valves is evaluated through in vitro accelerated fatigue testing (leaflets opening and closing 10 times per second or more). This experiment can obtain the overall fatigue life of the valve under idealized operating conditions and evaluate whether the valve as a whole meets regulatory standards. However, it has the following problems: 1) It takes 6-12 months to complete 200 million fatigue tests; 2) Valve fatigue testing equipment is expensive, and the cost of consumables for accelerated fatigue testing is high; 3) Fatigue testing requires professional personnel for instrument debugging, prosthetic valve sample installation, and manual data collection, which makes it difficult; 4) It is a fatigue test of the entire prosthetic valve, which cannot accurately evaluate the fatigue life of the artificial leaflets, resulting in low accuracy; 5) Fatigue testing relies on visual observation of leaflet damage, but the cracks that occur when the leaflets reach their 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 leaflet opening and closing cycles has already far exceeded the fatigue limit, and there is also the possibility of not detecting leaflet cracks in time, resulting in low accuracy; 6) Fatigue testing is an evaluation of the fatigue life of artificial valve leaflets based on the idealized operating conditions of the fatigue testing instrument. The working conditions of a prosthetic valve after implantation differ greatly from ideal working conditions, and the physiological and anatomical structures of different patients are also completely different. According to the knowledge of fatigue mechanics, the fatigue life of artificial valve leaflets is related to their structure and morphology. Therefore, although the prosthetic valve and artificial valve leaflets meet the regulatory requirements under ideal working conditions through accelerated fatigue testing, due to the different working conditions, there are cases in clinical practice where the valve leaflets in the patient's body fail before reaching their fatigue life, which leads to many limitations in testing. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method, system, device and medium for evaluating the fatigue life of artificial leaflets, so as to reduce the time, cost and difficulty required for evaluating the fatigue life of artificial leaflets, reduce the limitations of evaluating the fatigue life of artificial leaflets, and improve the accuracy and precision of evaluating the fatigue life of artificial leaflets.

[0005] To achieve the above and other related objectives, this invention proposes a method for evaluating the fatigue life of artificial leaflets, characterized by comprising:

[0006] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet;

[0007] The minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet is the fatigue life of the artificial leaflet.

[0008] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0009] Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles;

[0010] Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments, alternating stress of each load sequence, average stress of each load sequence, and number of cycles of each load sequence.

[0011] Calculate the number of fatigue failure cycles of the standard sample of artificial leaflet material corresponding to each load sequence;

[0012] The fatigue damage under each load sequence is calculated by calculating the ratio of the number of cycles to the number of fatigue failure cycles.

[0013] Obtain the sum of fatigue damage under all load orders, and obtain its reciprocal as the expected fatigue life.

[0014] In one embodiment of the present invention, the step of obtaining the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtaining the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment includes:

[0015] Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments of the stress load spectrum.

[0016] Obtain the minimum and maximum stresses in each load sequence;

[0017] The alternating stress and average stress under each load sequence are calculated based on the minimum stress and the maximum stress.

[0018] In one embodiment of the present invention, the alternating stress is half the difference between the maximum stress and the minimum stress; the average stress is half the sum of the maximum stress and the minimum stress.

[0019] In one embodiment of the present invention, the step of calculating the number of fatigue failure cycles of the standard sample of the artificial leaflet material corresponding to each load sequence includes:

[0020] When the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected, and the fatigue strength of the artificial leaflet material at the fatigue failure risk point is calculated based on the correction result.

[0021] When the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress of that load sequence is the fatigue strength of the artificial leaflet material at the fatigue failure risk point.

[0022] The number of fatigue failure cycles is calculated based on the relationship between fatigue strength and fatigue failure cycle count.

[0023] In one embodiment of the present invention, when the loads in the load sequence are non-pulsating cyclic loads and asymmetric cyclic loads, the loads in that load sequence are corrected using the Goodman equation or the Morrow equation.

[0024] Its Goodman equation is:

[0025] Among them, S a S represents the alternating stress for each load sequence; m S represents the average stress of each load sequence; Nf The fatigue strength of the artificial leaflet material; S u This represents the nominal ultimate tensile strength of the artificial leaflet material.

[0026] In one embodiment of the present invention, when the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected using the Morrow equation, which is:

[0027] Among them, S a S represents the alternating stress for each load sequence; m S represents the average stress of each load sequence; Nf The fatigue strength of the artificial leaflet material; σ f This represents the true ultimate tensile strength of the artificial leaflet material.

[0028] In one embodiment of the present invention, when the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected using the Gerber equation, which is: S a S represents the alternating stress for each load sequence; m S represents the average stress of each load sequence; Nf The fatigue strength of the artificial leaflet material; S u This represents the nominal ultimate tensile strength of the artificial leaflet material.

[0029] This invention also proposes an artificial leaflet fatigue life evaluation system, characterized in that it includes:

[0030] The expected fatigue life acquisition module is used to obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet.

[0031] The fatigue life acquisition module obtains the minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet, which is the fatigue life of the artificial leaflet.

[0032] The expected fatigue life acquisition module includes:

[0033] The stress load spectrum acquisition unit is used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles.

[0034] The stress load spectrum processing unit is used to obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and to obtain the number of load sequence segments, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence.

[0035] The fatigue failure cycle calculation unit is used to calculate the fatigue failure cycle of the standard sample of artificial leaflet material corresponding to each load sequence.

[0036] The expected fatigue life calculation unit is used to calculate the fatigue damage under each load sequence by calculating the ratio of the number of cycles to the number of fatigue failure cycles; and to obtain the sum of fatigue damage under all load sequences and obtain its reciprocal as the expected fatigue life.

[0037] The present invention also proposes an electronic device, including 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 the artificial leaflet fatigue life evaluation method as described in any of the above embodiments.

[0038] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, the computer program being used to cause a computer to execute the artificial leaflet fatigue life evaluation method as described in any of the above embodiments.

[0039] This invention proposes a method, system, device, and medium for evaluating the fatigue life of artificial valve leaflets. It calculates fatigue life by targeting typical fatigue failure risk points on the surface of the artificial valve leaflet. The calculation process uses the stress load spectrum of the artificial valve leaflet in the last cardiac cycle of several cardiac cycles, obtaining the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles for each load sequence segment. The fatigue life under each load sequence segment is then summed to obtain the expected fatigue life. This method has the following advantages: short calculation time (only about 1-10 hours for fatigue evaluation calculation of artificial valve leaflets under ideal working conditions); less than 5 days for fatigue evaluation calculation of artificial valve leaflets under extremely complex individual patient working conditions; and low cost. This method offers several advantages: First, it eliminates the need for expensive fatigue testing equipment and consumables. It utilizes virtual leaflet simulation and evaluation algorithms to determine the fatigue life of artificial leaflets. Second, it is easy to debug, as the fatigue evaluation and calculation equipment is simple to set up. It automatically collects data on leaflet stress and strain, and automatically calculates the fatigue life of the artificial leaflet without requiring a sample. Third, it boasts high accuracy, eliminating the influence of metal supports, skirts, and sutures, focusing solely on the fatigue life of the artificial leaflet. Fourth, it offers high precision, with the fatigue life (number of opening and closing cycles) of the artificial leaflet accurate to single digits. Fifth, it has few limitations, allowing for the evaluation and calculation of artificial leaflet fatigue life under any conditions, including idealized conditions similar to those of fatigue testing equipment and complex implantation conditions in different patients. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating the fatigue life evaluation method for artificial leaflets in one embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram illustrating the fatigue life calculation process for any fatigue failure risk point in one embodiment of the present invention.

[0043] Figure 3This is a schematic diagram illustrating the stress load spectrum of the integrated points on the surface of the artificial valve leaflet over five cardiac cycles in one embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of the stress load spectrum extracted during the last cardiac cycle in one embodiment of the present invention.

[0045] Figure 5 This is a schematic diagram of a simplified stress load spectrum experienced during the last cardiac cycle in one embodiment of the present invention.

[0046] Figure 6 This is a structural block diagram of an artificial leaflet fatigue life evaluation system in one embodiment of the present invention.

[0047] Figure 7 This is a structural block diagram of the artificial leaflet fatigue life evaluation calculation device in one embodiment of the present invention. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0050] Please see Figure 1 As shown, in this embodiment, the present invention proposes a method, system, device, and medium for evaluating the fatigue life of artificial leaflets, thereby reducing the time, cost, and difficulty required for evaluating the fatigue life of artificial leaflets, reducing the limitations of artificial leaflet fatigue life evaluation, and improving the accuracy and precision of artificial leaflet fatigue life evaluation. Specifically, the method for evaluating the fatigue life of artificial leaflets includes:

[0051] S1. Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet;

[0052] S2. The minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet is the fatigue life of the artificial leaflet.

[0053] For details, please refer to Figure 2As shown, in this embodiment, the step of obtaining the expected fatigue life corresponding to a fatigue failure risk point on the surface of the artificial leaflet includes:

[0054] S11. Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles; for example, the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles can be obtained through two-way fluid-structure interaction finite element simulation.

[0055] Understandably, during each cardiac cycle, the artificial valve leaflet completes one periodic opening and closing motion due to the flow field force. However, within one motion cycle, any point on the surface of the artificial valve leaflet is subjected to several varying stress loads. The total stress load on the artificial valve leaflet during one motion cycle constitutes the stress load spectrum at that point, which is implemented for example... Figure 3 As shown, the stress load spectrum of any point on the surface of the artificial valve is obtained over 5 cardiac cycles. Due to the calculation error caused by the initial start-up of the multi-field coupling calculation, the stress load spectrum of this point in the first 1-2 cardiac cycles does not have a periodicity. However, the calculation error is gradually eliminated in the 3-5 cardiac cycles, and the hydrodynamic characterization of each cardiac cycle tends to be consistent, and the stress load spectrum shows a periodicity.

[0056] S12. Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment.

[0057] Understandably, the rainflow counting method can be used to extract all sub-cycles within the load spectrum and record the number n of identical sub-cycles. The rainflow counting method involves rotating the stress-time history data record of the stress load spectrum by 90°, with the time axis vertically downwards. The data record resembles a series of rooftops from which rainwater flows down, hence the name rainflow counting method. The main function of the rainflow counting method is to simplify the measured load history into several load cycles for use in fatigue life estimation and compiling fatigue test load spectra. Based on the two-parameter method, it considers two variables: dynamic intensity (amplitude) and static intensity (mean), conforming to the inherent characteristics of fatigue loads. Its basic counting principle is:

[0058] Rain flowed down the slope sequentially from the inside of the peak position of the load time history;

[0059] Rain flow begins at a certain peak point and stops flowing when it encounters a peak larger than its initial peak.

[0060] When a stream of rain meets a stream of rain flowing down from above, it must stop flowing.

[0061] Extract all full loops and record the amplitude of each loop;

[0062] The remaining divergent-convergent load time history after the first stage of counting is equivalent to a convergent-divergent load time history, and the second stage of rainflow counting is performed. The total number of counting cycles is equal to the sum of the counting cycles of the two counting stages.

[0063] In this embodiment, since the calculation error is gradually eliminated in the 3rd to 5th cardiac cycles, the hydrodynamic characterization of each cardiac cycle tends to be consistent, and the stress load spectrum exhibits a periodic pattern. Therefore, the stress load spectrum of the last (5th) cardiac cycle at that point can be extracted. For the last cardiac cycle, please refer to [link to relevant documentation]. Figure 4 As shown, the number of load sequence segments and the alternating stress S of each load sequence segment in the stress load spectrum are obtained by rainflow counting method. a / MPa, average stress S for each load sequence m / MPa and the number of cycles n for each load sequence. Of course, if the number of cardiac cycles calculated by multi-field coupling is greater (e.g., calculated up to the 10th cardiac cycle), the stress load spectrum of the points within the 10th cardiac cycle should be extracted.

[0064] Understandably, to reduce the computational burden of rainflow counting, the stress load spectrum can be simplified; please refer to [link / reference needed]. Figure 5 As shown, Figure 5 Yes Figure 4 The stress load spectrum of the last cardiac cycle is simplified by treating similar peak values ​​in the load spectrum as equal and taking the average value, thereby simplifying the load spectrum and reducing the amount of calculation.

[0065] In this embodiment, the step of obtaining the number of load sequence segments, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence from the stress load spectrum of the last cardiac cycle within n cardiac cycles includes:

[0066] S121. Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments of the stress load spectrum.

[0067] S122. Obtain the minimum stress S in each load sequence. min / MPa and maximum stress S max / Mpa;

[0068] S123. Calculate the alternating stress and average stress for each load sequence based on the minimum stress and the maximum stress. Wherein, the alternating stress S... a The maximum stress S maxand the minimum stress S min Half of the difference; the average stress S m The maximum stress S max With minimum stress S min One-half of the sum.

[0069] Based on the rainflow counting method, in Figure 5 The stress-load spectrum at this point contains eight load sequences, each with a minimum stress S. min / MPa and maximum stress S max / MPa, then according to the formula The alternating stress S in each load sequence a / MPa, according to the formula Calculate the average stress S for each load sequence. m / MPa, the number of cycles n in each load sequence can be obtained by counting the total number of cycles of the force value. In this embodiment, the number of cycles of the 8 load sequences are denoted as n1, n2, ..., n8.

[0070] S13. Calculate the number of fatigue failure cycles of the artificial leaflet material standard sample corresponding to each load sequence; in this embodiment, the step of calculating the number of fatigue failure cycles of the artificial leaflet material standard sample corresponding to each load sequence includes:

[0071] When the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected, and the fatigue strength of the artificial leaflet material at the fatigue failure risk point is calculated based on the correction result.

[0072] The number of fatigue failure cycles is calculated based on the relationship between fatigue strength and fatigue failure cycle count.

[0073] In this embodiment, when the fatigue SN curve of the material describes the number of symmetrical cycles required for fatigue failure at different stress levels, the load order of the asymmetric cycle can be corrected using either the Goodman equation or the Morrow equation.

[0074] Its Goodman equation is:

[0075] Among them, S u The nominal ultimate tensile strength of the artificial leaflet material is an inherent material constant that can be obtained through mechanical experiments on the artificial leaflet material.

[0076] Its Morrow equation is:

[0077] Where, σ f The true ultimate tensile strength of the artificial leaflet material is an inherent material constant.

[0078] In another embodiment, when the fatigue SN curve of the material describes the number of pulsating cycles required for fatigue failure at different stress levels, it is preferable to use the Gerber equation to correct all load cycles in the load sequence to pulsating cycles, so as to unify the load form. The correction equation is as follows:

[0079] At this time, S Nf This refers to the fatigue strength of the material under complete pulsating cycling.

[0080] In this embodiment, when the artificial leaflet has been in operation for more than 10 years, the number of cycles is expected to exceed 10 to the power of 8, which is considered ultra-high cycle fatigue. Therefore, the fatigue intensity and the number of fatigue failure cycles are related as follows:

[0081] S Nf =σ' f (2N f1 ) b , among which, S Nf Artificial leaflet materials are in a completely symmetrical cycle and at 2N f1 Fatigue strength at the following level: 2N f1 N in f1 This refers to the number of half-cycles of fatigue failure in an artificial leaflet material under fully symmetrical cyclic tensile stress. A full cycle refers to the number of complete cycles from maximum stress to minimum stress and back to maximum stress, while a half-cycle refers to the number of unidirectional stress changes from maximum stress to minimum stress (or vice versa). Therefore, the two half-cycle numbers together constitute the full cycle number. 2N f1 It is an inherent material constant, which can be obtained from the fatigue life curve of the artificial leaflet material. σ' f 'b' is the single-cycle fatigue strength coefficient of the artificial leaflet material, an inherent material constant, which can be obtained from the fatigue life curve of the artificial leaflet material. 'b' is the fatigue life exponent, an inherent material constant used to describe the relationship between fatigue life and stress level, i.e., the slope of the fatigue life curve, which can also be obtained from the fatigue life curve of the artificial leaflet material. It is understood that the fatigue life exponent 'b' is preferably the slope 'k' of the high-cycle fatigue segment of the Asquin-type SN curve.

[0082] In this embodiment, the fatigue life curve of the artificial leaflet material can be obtained first, the fatigue life index can be obtained based on the fatigue life curve, and the corresponding correction equation described in the above embodiment can be selected according to the method of obtaining the fatigue life curve.

[0083] In this embodiment, the equation is based on the Goodman modified equation and the above formula S. Nf =σ' f (2N f1 ) b Taking this as an example, the number of fatigue failure cycles can be calculated.

[0084] It is understandable that, since the reciprocal of the number of fatigue failures of the standard sample material is the fatigue damage, in this embodiment, when the load of the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load of this load sequence needs to be corrected. The fatigue failure number of the standard sample material corresponding to the artificial leaflet is obtained by using the corrected fatigue strength, thereby calculating its fatigue damage.

[0085] Of course, in some other embodiments, if the fatigue life curve used is obtained based on a full-cycle tensile test, then S Nf =σ' f (2N f1 ) b Change to S Nf =σ' f (N f2 ) b At this time N f2 This refers to the number of full cycles of fatigue failure of artificial leaflet materials under fully symmetrical cyclic tensile stress.

[0086] When the load sequence is a pulsating cyclic load or a symmetrical cyclic load, then the alternating stress S of that load sequence is... a That is, the fatigue strength S of the artificial leaflet material at the fatigue failure risk point. Nf ,at this time,

[0087] S14. Calculate the fatigue damage under each load sequence by the ratio of the number of cycles to the number of fatigue failure cycles; specifically, the ratio of the number of cycles n to the number of fatigue failure cycles N under each load sequence is... f ratio This refers to the fatigue damage under that load sequence.

[0088] S15. Obtain the sum of fatigue damage under all load sequences and take its reciprocal as the expected fatigue life. It can be understood that when the total cumulative damage equals 1, the material is considered to have reached its fatigue life; therefore, the expected fatigue life L can be derived as follows: Where N fi Let n be the number of fatigue failure cycles under the i-th load order. i Number of cycles under the i-th load order.

[0089] Understandably, based on the principles of materials mechanics and fracture mechanics, points with high maximum stress values ​​are at risk of fatigue failure, meaning they have poor fatigue life and are more prone to tearing and breakage. Therefore, the preferred selection point should be one with a high maximum stress value. Stress concentration areas are high-risk areas for fatigue failure, and the fatigue life of the material at the point of maximum stress integration represents the overall lifespan of the artificial leaflet. The load spectrum of the point of maximum stress integration on the artificial leaflet surface can be extracted over a complete cardiac cycle. Of course, any other point of interest besides those with high stress values ​​can be used as a stress-load spectrum extraction point.

[0090] It should be understood that the sequence number of each step in the above embodiments does not imply 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.

[0091] Please see Figure 6 As shown, the present invention provides an artificial leaflet fatigue life evaluation system, which corresponds to the artificial leaflet fatigue life evaluation method one in the above embodiments. Figure 6 This is a structural block diagram of an artificial leaflet fatigue life evaluation system proposed in this invention. The artificial leaflet fatigue life evaluation system 100 includes a desired fatigue life acquisition module 10 and a fatigue life acquisition module 20. Detailed descriptions of each functional module are as follows:

[0092] The expected fatigue life acquisition module 10 is used to acquire the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet.

[0093] The fatigue life acquisition module 20 obtains the minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet, which is the fatigue life of the artificial leaflet.

[0094] The expected fatigue life acquisition module 10 includes a stress load spectrum acquisition unit 11, a stress load spectrum processing unit 12, a fatigue failure cycle count calculation unit 13, and an expected fatigue life calculation unit 14. Detailed descriptions of each functional module are as follows:

[0095] The stress load spectrum acquisition unit 11 is used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point within several cardiac cycles;

[0096] The stress load spectrum processing unit 12 is used to obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and to obtain the number of load sequence segments, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence.

[0097] The fatigue failure cycle calculation unit 13 is used to calculate the fatigue failure cycle of the standard sample of artificial leaflet material corresponding to each load sequence.

[0098] The expected fatigue life calculation unit 14 is used to calculate the fatigue damage under each load sequence based on the number of fatigue failure cycles and the number of cycles under each load sequence; and to obtain the sum of fatigue damage under all load sequences and obtain its reciprocal as the expected fatigue life.

[0099] Specific limitations regarding the artificial leaflet fatigue life evaluation system can be found in the limitations of the artificial leaflet fatigue life evaluation method described above, and will not be repeated here. Each module in the aforementioned artificial leaflet fatigue life evaluation system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0100] Please see Figure 7 As shown, this invention also proposes a fatigue life evaluation and calculation device for prosthetic valve leaflets. This device can evaluate and calculate the lifespan of prosthetic valve leaflets for prosthetic valves requiring long-term in vitro fatigue testing, or for implanted prosthetic valve leaflets, based on input prosthetic valve product data, in vitro experimental data, and clinical data. Specifically, it includes a data exchange module 101, a 3D modeling module 102, a virtual experiment & virtual surgery module 103, a multi-field coupling calculation module 104, a fatigue life evaluation module 105, and a human-computer interaction module 106. Detailed descriptions of each functional module are as follows:

[0101] The data exchange module 101 is used to collect and store prosthetic valve product data, in vitro experimental data and clinical data, and transmit this data to the 3D modeling module 102 and the human-computer interaction module 106.

[0102] Prosthetic valves typically consist of a metal framework, artificial leaflets, and a skirt. The metal framework is often made of metals such as cobalt-chromium alloy or nickel-titanium alloy. The artificial leaflets can be made from biological tissues such as porcine or bovine pericardium, or from polymeric materials such as expanded polytetrafluoroethylene (ePTFE) or polyethylene terephthalate (PET), mimicking the shape of natural human valve leaflets. The skirt, also typically made of ePTFE or PET, serves a sealing function.

[0103] The valve product data described in this invention includes the dimensional and structural parameters (such as the diameter of the metal stent and the height of the artificial leaflet) and material parameters (such as the elastic modulus of the metal stent material and the fatigue life curve of the artificial leaflet material). The above data can be input into the product parameters based on the actual structural design of the prosthetic valve being used, ensuring the completeness of these dimensional and structural parameters and material parameters.

[0104] In the in vitro biomimetic circulation test of the prosthetic valve, the prosthetic valve is loaded and fixed in a receiving structure. Liquid flows in from the inlet end and then flows out from the outlet end to simulate the flow of blood in the body, causing the artificial valve leaflets to open and close.

[0105] The in vitro experimental data described in this invention refers to the internal spatial dimensions of the prosthetic valve, the liquid pressure applied at the inflow end, and the liquid parameters applied at the outflow end during in vitro biomimetic circulation testing 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 serve as load inputs for subsequent multi-field coupling calculations. It is understood that if other structural experimental instruments are used, the dimensional parameters of the containment structure should be input according to the actual situation to ensure the integrity of these dimensions and structures.

[0106] In vitro experimental data may also include experimental results such as liquid flow rate and liquid pressure, which can be used to compare and verify the results of subsequent multi-field coupling calculations.

[0107] The clinical data described in this 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 subsequent 3D model reconstruction and virtual surgical boundary conditions, while postoperative data can be used for comparison and verification of subsequent virtual surgical and multi-field coupling calculation results.

[0108] The clinical data described in this invention uses the aortic valve as an example only. If other valves (such as mitral, tricuspid, pulmonary, or lower extremity venous valves) are used, multimodal image data of the corresponding location should be input according to the actual situation, and it should be ensured that a three-dimensional model of the native valve tissue and its surrounding tissues can be completed using only one image.

[0109] The 3D modeling module 102 uses the prosthetic valve product data, in vitro experimental data and clinical data in the data exchange module 101 to construct a 3D model of the prosthetic valve, a 3D model of the flow field in the in vitro experiment and a 3D model of the individualized tissue structure. It can also communicate with the human-computer interaction module 106 to provide feedback on the progress and results of the 3D model construction.

[0110] Taking the preoperative aortic valve as an example, the 3D modeling module 102 first constructs a tissue 3D model directly based on the influence data, but this type of model is relatively coarse. Then, the 3D modeling module 102 performs smoothing, repair and other operations on the coarse 3D model to further refine the model into a preoperative 3D model that can be used for virtual surgery and multi-field coupling calculation. At the same time, the internal space of this preoperative 3D model is the individualized flow field 3D model.

[0111] The virtual experiment & virtual surgery module 103 can simulate real experimental and surgical operations based on the finite element algorithm. The three-dimensional model of the prosthetic valve product constructed by the three-dimensional modeling module 102 can be implanted into the in vitro experimental structure or the preoperative three-dimensional model according to the actual experimental or surgical operation.

[0112] The three-dimensional model of the prosthetic valve product is implanted. Through the same pressure, intervention, release, and balloon expansion operations as the actual surgery, it is implanted into the preoperative three-dimensional model, thus completing the virtual surgical procedure 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).

[0113] The virtual experimental implantation process involves implanting a 3D model of the prosthetic valve product into an in vitro experimental structure, thus obtaining a virtual experimental implantation model. The virtual experimental implantation process is similar to the virtual surgical implantation process and will not be described in detail here.

[0114] The multi-field coupling calculation module 104, based on computational fluid dynamics theory, adaptive mesh theory, submerged boundary theory, and arbitrary Lagrange-Euler theory, obtains a virtual experimental implantation model or a three-dimensional model after virtual surgery based on the virtual experiment & virtual surgery module 103. It embeds the aortic constitutive equation inverted from multimodal image data, the leaflet constitutive equation fitted based on uniaxial / biaxial tensile tests and Bayesian inferences of the Mooney-Rivlin constitutive equation, and embeds the dynamic pressure curves of the patient's left ventricle and ascending aorta measured by Doppler ultrasound as load inputs. It uses the ascending aortic blood flow velocity based on 4D Flow as a verification condition, applies a bidirectional fluid-structure coupling algorithm to reconstruct fluid dynamics, the kinematics of the vessel wall and leaflets, and constructs a multi-field coupling calculation model of blood flow-vessel wall-valve (i.e., simulating liquid flow and driving the opening and closing motion of the artificial leaflets). It outputs multi-dimensional information such as leaflet morphological parameters, leaflet mechanical functional parameters, liquid ejection angle, and liquid flow trend.

[0115] The fatigue life evaluation module 105, based on the multi-dimensional information output by the multi-field coupling calculation module 104, including the morphological parameters of the artificial valve leaflet, the mechanical functional parameters of the leaflet, and the blood flow trend, first obtains the stress load spectrum of the fatigue failure risk points on the surface of the artificial valve leaflet. Then, it calculates the fatigue intensity of each load sequence in the stress load spectrum using the rainflow counting method and the Goodman criterion. Finally, it calculates the fatigue life of that point using the superposition principle, and finally completes the calculation of the expected fatigue life of the artificial valve leaflet. It can be understood that this fatigue life evaluation module 105 is the same as the artificial valve leaflet fatigue life evaluation system described in the above embodiment, and corresponds to the artificial valve leaflet fatigue life evaluation method one in the above embodiment.

[0116] Please see Figure 1 and Figure 2 As shown, this application also proposes an electronic device, including 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, it performs the following steps:

[0117] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet;

[0118] The minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet is the fatigue life of the artificial leaflet.

[0119] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0120] Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles;

[0121] Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments, alternating stress of each load sequence, average stress of each load sequence, and number of cycles of each load sequence.

[0122] Calculate the number of fatigue failure cycles of the standard sample of artificial leaflet material corresponding to each load sequence;

[0123] The fatigue damage under each load sequence is calculated by calculating the ratio of the number of cycles to the number of fatigue failure cycles.

[0124] Obtain the sum of fatigue damage under all load orders, and obtain its reciprocal as the expected fatigue life.

[0125] Please see Figure 1 and Figure 2As shown, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, performs the following steps:

[0126] Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet;

[0127] The minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet is the fatigue life of the artificial leaflet.

[0128] The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include:

[0129] Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles;

[0130] Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments, alternating stress of each load sequence, average stress of each load sequence, and number of cycles of each load sequence.

[0131] Calculate the number of fatigue failure cycles of the standard sample of artificial leaflet material corresponding to each load sequence;

[0132] The fatigue damage under each load sequence is calculated by calculating the ratio of the number of cycles to the number of fatigue failure cycles.

[0133] Obtain the sum of fatigue damage under all load orders, and obtain its reciprocal as the expected fatigue life.

[0134] It should be noted that the functions or steps that can be implemented by the computer-readable storage medium or computer device described above can be referred to in the foregoing method embodiments. To avoid repetition, they will not be described one by one here.

[0135] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, 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), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0136] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to 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.

[0137] This invention proposes a method, system, device, and medium for evaluating the fatigue life of artificial valve leaflets. It calculates fatigue life by targeting typical fatigue failure risk points on the surface of the artificial valve leaflet. The calculation process uses the stress load spectrum of the artificial valve leaflet in the last cardiac cycle of several cardiac cycles, obtaining the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles for each load sequence segment. The fatigue life under each load sequence segment is then summed to obtain the expected fatigue life. This method has the following advantages: short calculation time (only about 1-10 hours for fatigue evaluation calculation of artificial valve leaflets under ideal working conditions); less than 5 days for fatigue evaluation calculation of artificial valve leaflets under extremely complex individual patient working conditions; and low cost. This method offers several advantages: First, it eliminates the need for expensive fatigue testing equipment and consumables. It utilizes virtual leaflet simulation and evaluation algorithms to determine the fatigue life of artificial leaflets. Second, it is easy to debug, as the fatigue evaluation and calculation equipment is simple to set up. It automatically collects data on leaflet stress and strain, and automatically calculates the fatigue life of the artificial leaflet without requiring a sample. Third, it boasts high accuracy, eliminating the influence of metal supports, skirts, and sutures, focusing solely on the fatigue life of the artificial leaflet. Fourth, it offers high precision, with the fatigue life (number of opening and closing cycles) of the artificial leaflet accurate to single digits. Fifth, it has few limitations, allowing for the evaluation and calculation of artificial leaflet fatigue life under any conditions, including idealized conditions similar to those of fatigue testing equipment and complex implantation conditions in different patients.

[0138] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

[0139] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A method for evaluating the fatigue life of artificial leaflets, characterized in that, include: Obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet; The minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet is the fatigue life of the artificial leaflet. The steps for obtaining the expected fatigue life corresponding to each fatigue failure risk point include: Obtain the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles; Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments, alternating stress of each load sequence, average stress of each load sequence, and number of cycles of each load sequence. Calculate the number of fatigue failure cycles of the standard sample of artificial leaflet material corresponding to each load sequence; The fatigue damage under each load sequence is calculated by calculating the ratio of the number of cycles to the number of fatigue failure cycles. Obtain the sum of fatigue damage under all load orders, and obtain its reciprocal as the expected fatigue life; The step of calculating the number of fatigue failure cycles of the standard sample of the artificial leaflet material corresponding to each load sequence includes: When the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected, and the fatigue strength of the artificial leaflet material at the fatigue failure risk point is calculated based on the correction result. When the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress of that load sequence is the fatigue strength of the artificial leaflet material at the fatigue failure risk point. The number of fatigue failure cycles is calculated based on the relationship between fatigue strength and fatigue failure cycle count.

2. The method for evaluating the fatigue life of artificial leaflets according to claim 1, characterized in that, The steps of obtaining the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtaining the number of load sequence segments, the alternating stress of each load sequence segment, the average stress of each load sequence segment, and the number of cycles of each load sequence segment include: Obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and obtain the number of load sequence segments of the stress load spectrum. Obtain the minimum and maximum stresses in each load sequence; The alternating stress and average stress under each load sequence are calculated based on the minimum stress and the maximum stress.

3. The method for evaluating the fatigue life of artificial leaflets according to claim 2, characterized in that, The alternating stress is half the difference between the maximum stress and the minimum stress; the average stress is half the sum of the maximum stress and the minimum stress.

4. The method for evaluating the fatigue life of artificial leaflets according to claim 1, characterized in that, When the loads in the load sequence are non-pulsating cyclic loads and asymmetric cyclic loads, the loads in that load sequence are corrected using the Goodman equation or the Morrow equation. Its Goodman equation is: , in, The alternating stress for each load sequence; The average stress for each load sequence; The fatigue strength of artificial leaflet materials; This represents the nominal ultimate tensile strength of the artificial leaflet material.

5. The method for evaluating the fatigue life of artificial leaflets according to claim 1, characterized in that, When the loads in the load sequence are non-pulsating cyclic loads and asymmetric cyclic loads, the loads in this load sequence are corrected using the Morrow equation, which is as follows: , in, The alternating stress for each load sequence; The average stress for each load sequence; The fatigue strength of artificial leaflet materials; This represents the true ultimate tensile strength of the artificial leaflet material.

6. The method for evaluating the fatigue life of artificial leaflets according to claim 1, characterized in that, When the loads in the load sequence are non-pulsating cyclic loads and asymmetric cyclic loads, the loads in this load sequence are corrected using the Gerber equation, which is as follows: , The alternating stress for each load sequence; The average stress for each load sequence; The fatigue strength of artificial leaflet materials; This represents the nominal ultimate tensile strength of the artificial leaflet material.

7. A fatigue life evaluation system for artificial leaflets, characterized in that, include: The expected fatigue life acquisition module is used to obtain the expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet. The fatigue life acquisition module obtains the minimum expected fatigue life corresponding to all fatigue failure risk points on the surface of the artificial leaflet, which is the fatigue life of the artificial leaflet. The expected fatigue life acquisition module includes: The stress load spectrum acquisition unit is used to acquire the stress load spectrum of the artificial valve leaflet surface fatigue failure risk point over several cardiac cycles. The stress load spectrum processing unit is used to obtain the stress load spectrum of any cardiac cycle after the load trend of several cardiac cycles has stabilized, and to obtain the number of load sequence segments, the alternating stress of each load sequence, the average stress of each load sequence, and the number of cycles of each load sequence. The fatigue failure cycle calculation unit is used to calculate the fatigue failure cycle number of the standard sample of the artificial leaflet material corresponding to each load sequence; wherein, the step of calculating the fatigue failure cycle number of the standard sample of the artificial leaflet material corresponding to each load sequence includes: When the load in the load sequence is a non-pulsating cyclic load and an asymmetric cyclic load, the load in that load sequence is corrected, and the fatigue strength of the artificial leaflet material at the fatigue failure risk point is calculated based on the correction result. When the load sequence is a pulsating cyclic load or a symmetrical cyclic load, the alternating stress of that load sequence is the fatigue strength of the artificial leaflet material at the fatigue failure risk point. The number of fatigue failure cycles is calculated based on the relationship between fatigue strength and fatigue failure cycle count. The expected fatigue life calculation unit is used to calculate the fatigue damage under each load sequence by calculating the ratio of the number of cycles to the number of fatigue failure cycles; and to obtain the sum of fatigue damage under all load sequences and obtain its reciprocal as the expected fatigue life.

8. An electronic device, characterized in that, It includes 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 the artificial leaflet fatigue life evaluation method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, It stores a computer program that enables the computer to perform the artificial leaflet fatigue life evaluation method as described in any one of claims 1-6.

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