Device and method for evaluating durability of heart valve prosthesis

Abstract

The invention discloses an artificial heart valve durability evaluation device and a test method, and relates to the technical field of fatigue test, and the artificial heart valve durability evaluation device is provided with a driving unit, a distribution container, a plurality of test units, a measurement and control unit and a test platform. The driving unit is composed of a linear motor, an air cylinder and the like and drives related parts to move. The distribution container is communicated with a rodless cavity of the cylinder; each testing unit comprises a corrugated pipe, a connecting pipe, a valve fixing mechanism and the like, and valve installation and communication are achieved. The measurement and control unit monitors and regulates pressure. The position of the artificial heart valve is fixed in the channel, and the liquid medium is driven by the single motor to flow back and forth in the channel, so that the artificial valve is opened or closed; liquid is distributed into the multiple testing units through the distribution container, the structure is simple, distribution is uniform, stability is high, the corrugated pipe is arranged to respond to high-frequency vibration, the characteristics of elastic deformation energy storage are utilized, actual working conditions such as fluid pressure and flowing which are closer to the interior of the human heart are created in the testing process, and accuracy is high.

Description

Technical Field

[0001] This invention relates to the field of fatigue testing technology, and in particular to equipment and testing methods for evaluating the durability of artificial heart valves. Background Technology

[0002] Once implanted, artificial heart valves remain in the body long-term. With each heartbeat, the valve leaflets open and close to guide normal blood flow. However, if the artificial heart valve becomes structurally damaged during long-term use, it will be unable to perform its physiological functions, and in severe cases, may even lead to the patient's death. Therefore, before clinical use, it is essential to evaluate the long-term fatigue resistance of artificial heart valves in a simulated in vivo environment.

[0003] Currently, existing valve fatigue life testing devices typically rely on simple mechanical drives to open and close valve leaflets, which cannot simulate the in vivo environment. Therefore, the test results are not accurate. Summary of the Invention

[0004] The purpose of this invention is to provide an artificial heart valve durability evaluation device and testing method to solve the problems existing in the prior art and improve the accuracy of artificial heart valve fatigue life testing.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] In a first aspect, the present invention provides an artificial heart valve durability evaluation device, comprising:

[0007] Test platform;

[0008] The drive unit includes a linear motor and a cylinder respectively fixed on the test platform. The linear motor is used to drive the piston rod of the cylinder to perform reciprocating linear motion. A liquid inlet valve communicating with the rodless chamber of the cylinder is provided on the side wall of the cylinder.

[0009] A dispensing container, which is connected to the rodless chamber of the cylinder, and the top of the dispensing container is sealed;

[0010] The system comprises several test units, each including, from top to bottom, a corrugated tube, a first connecting tube, a valve fixing mechanism, and a second connecting tube. The bottom end of the second connecting tube communicates with the top end of the dispensing container. The bottom end of the first connecting tube and the top end of the second connecting tube are detachably connected to the valve fixing mechanism, which is located at the top end of the second connecting tube and is used to clamp the artificial heart valve to be tested. The bottom end of the corrugated tube is connected to the top end of the first connecting tube, and the top end of the corrugated tube is closed. Each test unit also includes a bypass tube, one end of which communicates with the first connecting tube and the other end of which communicates with the dispensing container. A resistance valve is provided on the bypass tube.

[0011] The measurement and control unit includes a controller, an inverted pressure sensor, and a post-valve pressure sensor. The linear motor, the inverted pressure sensor, and the post-valve pressure sensor are respectively connected to the controller via signals. A pre-valve pressure measuring port communicating with the second connecting pipe is provided on the second connecting pipe, and a post-valve pressure measuring port communicating with the first connecting pipe is provided on the first connecting pipe. The inverted pressure sensor is installed on the pre-valve pressure measuring port, and the post-valve pressure sensor is installed on the post-valve pressure measuring port.

[0012] Preferably, the drive unit further includes a linear guide rail fixed on the test platform and a slider that slides with the linear guide rail, the output end of the linear motor is fixedly connected to the slider, and the slider is fixedly connected to the piston rod of the cylinder through a coupling.

[0013] Preferably, an exhaust valve is also provided at the top of the bellows.

[0014] Preferably, it also includes a drain pipe, wherein the dispensing container is connected to the rodless chamber of the cylinder via a three-way pipe, one port of the three-way pipe is connected to the dispensing container, another port is connected to the rodless chamber of the cylinder, and yet another port is connected to one end of the drain pipe, and a drain valve is provided on the drain pipe.

[0015] Preferably, the linear motor is a voice coil motor.

[0016] Preferably, the cylinder is a rolling diaphragm cylinder.

[0017] Preferably, the first connecting pipe is connected to the second connecting pipe via a quick-connect fitting.

[0018] Preferably, the valve fixation mechanism includes a sleeve and a pressure ring, the sleeve portion is inserted into the second connecting tube, and the outer wall of the sleeve is bonded to the inner wall of the second connecting tube;

[0019] A support ring is fixed on the inner wall of the sleeve, and a pressure ring is threadedly connected to the inner wall of the sleeve. The pressure ring is used to cooperate with the support ring to clamp the edge of the artificial heart valve to be tested.

[0020] Preferably, a socket is provided on the top surface of the pressure ring for inserting a screwdriver.

[0021] Secondly, the present invention provides a method for testing the fatigue life of an artificial heart valve based on the aforementioned artificial heart valve durability evaluation device, comprising:

[0022] Through the inlet valve on the side wall of the cylinder, an appropriate amount of test liquid is injected into the rodless chamber of the cylinder and the distribution container connected thereto, until the artificial heart valve durability evaluation device is filled with test liquid.

[0023] Based on the controller in the measurement and control unit, the motion parameters of the linear motor are set; the motion parameters are used to determine the reciprocating motion law of the piston rod in the cylinder; the piston rod in the cylinder is used to simulate the aortic pressure waveform of a set frequency through reciprocating motion; the linear motor is a voice coil linear motor; the motion parameters include: initial motor position, voice coil motor point-to-point running position, motor stop position, voice coil motor periodic running waveform, voice coil motor periodic running amplitude, voice coil motor periodic running frequency, voice coil single-machine periodic running offset, and voice coil motor periodic running phase offset.

[0024] A segmented adjustment method is adopted to set the pressure thresholds of the prevalvular pressure sensor and the postvalvular pressure sensor in the measurement and control unit. The pressure thresholds are used to monitor the pressure before and after the artificial heart valve. The segmented adjustment method is based on the PVT control mode. Initial pressure adjustment is performed. When the set threshold is reached, low-frequency cycle operation is started. When the fatigue pressure waveform that meets the high / low / average pressure of the low-frequency cycle is obtained, the operating frequency is increased and pressure adjustment continues until the set fatigue frequency is reached.

[0025] Start the linear motor and acquire and record the pressure data before and after the artificial heart valve in the prevalvular pressure sensor and postvalvular pressure sensor; the pressure data includes prevalvular pressure and postvalvular pressure.

[0026] Based on the pressure data before and after the artificial heart valve, the maximum prevalence pressure, average prevalence pressure, minimum prevalence pressure, maximum postvalence pressure, average postvalence pressure, minimum postvalence pressure, and peak transvalvular pressure gradient at valve closure are calculated within one opening and closing cycle.

[0027] According to the valve fatigue performance verification guidelines in the international standard ISO 5840, the maximum value, average value, minimum value, maximum value, average value, minimum value, and peak closure transvalvular pressure gradient of the artificial heart valve durability evaluation equipment are adjusted by setting the operating amplitude, frequency, offset, and phase offset of the voice coil motor.

[0028] The device monitors the maximum, average, minimum, maximum, average, minimum, and peak transvalvular pressure of the tested valve in the artificial heart valve durability evaluation equipment.

[0029] When the monitored postvalvular pressure and peak valve closure transvalvular pressure difference do not meet the valve fatigue performance verification guidelines in the international standard ISO 5840, the operating amplitude, frequency, offset, and phase offset of the voice coil motor are adjusted based on the PID adaptive algorithm until the postvalvular pressure and peak valve closure transvalvular pressure difference meet the valve fatigue performance verification guidelines in the international standard ISO 5840.

[0030] The present invention achieves the following technical effects compared to the prior art:

[0031] The artificial heart valve durability evaluation equipment and testing method provided by this invention improves the accuracy of artificial heart valve fatigue life testing by simulating the blood flow pressure of the human aorta.

[0032] Furthermore, existing valve fatigue life testing devices typically only mechanically drive the valve leaflets to open and close, failing to simulate the in vivo environment and leading to inaccurate test results. In contrast, the drive unit of this invention uses a linear motor to drive the piston rod of a cylinder in reciprocating linear motion. Simultaneously, the cylinder's side wall is equipped with a liquid inlet valve communicating with the rodless chamber, and the distribution container is connected to the rodless chamber of the cylinder. These features create fluid pressure and flow conditions more closely resembling those inside the human heart during testing. This allows for testing of artificial heart valves in an environment more closely aligned with their actual usage scenarios, thereby improving the consistency between test results and actual conditions, and thus increasing test accuracy. Secondly, the artificial heart valve durability evaluation device of this invention distributes the working fluid to each test unit through the distribution container. Since each test unit operates independently, all test units can simultaneously perform durability evaluations of the artificial heart valves, improving evaluation efficiency.

[0033] Furthermore, the controller is connected to the linear motor, the prevalence pressure sensor, and the postvalence pressure sensor respectively. The prevalence and postvalence pressure sensors can monitor the pressure in front of and behind the valve in real time and feed it back to the controller. This allows for precise control of the testing process based on the actual pressure data, ensuring that the testing environment is closer to the real in vivo environment and thus improving the accuracy of the test.

[0034] Furthermore, the bottom end of the first connecting tube and the top end of the second connecting tube in each test unit are detachably connected (e.g., connected via quick-connect couplings). This design allows for convenient and quick disassembly and replacement of components if a component malfunctions or if a different specification of artificial heart valve needs to be replaced during testing, without requiring large-scale disassembly and reassembly of the entire test equipment, thus improving the convenience of testing and the maintainability of the equipment.

[0035] Furthermore, the number of test units in this invention can be adaptively set as needed, and multiple test units can be set at the same time. This allows multiple artificial heart valves to be tested simultaneously in one test, improving testing efficiency.

[0036] Furthermore, the linear motor uses a voice coil motor, which features fast response speed and high precision. It can more accurately drive the reciprocating motion of the piston rod in the cylinder, thereby better simulating the regular movement of the heart valves in the body as the heart beats, ensuring the accuracy and stability of the test.

[0037] Furthermore, the cylinder adopts a rolling diaphragm cylinder, which has good sealing and stability during operation, effectively preventing gas or liquid leakage and ensuring the stability of the test environment, thereby improving the accuracy and reliability of the test.

[0038] Furthermore, during the heartbeat, the human heart experiences periodic pressure changes on the heart valves. During heart contraction, the blood exerts higher pressure on the valves, pushing them open; during diastole, the pressure decreases, and the valves close. In this invention, the elastic deformation of a bellows is used to simulate vascular compliance. In this embodiment, after the air inside the bellows is completely expelled, the bellows is filled with working fluid, which acts directly on the bellows. The elastic deformation of the bellows occurs faster than that of air, thus achieving a faster response compared to existing methods that simulate vascular compliance using air. Moreover, in practical applications, a bellows with appropriate stiffness can be selected based on the required pressure and response frequency. It is important to ensure that the natural frequency of the bellows is not inconsistent with the system's operating frequency to avoid resonance. This solution utilizes the elastic deformation of a bellows to simulate vascular compliance, compared to existing methods that use air cavities. By setting parameters such as the bellows material, wave pitch, wave thickness, and wave depth coefficient k, the solution achieves a bellows whose energy storage capacity, pressure response, oscillation attenuation coefficient, and frequency are adapted to the valve fatigue requirements. This simulates the compliance and resilience of the aorta. Furthermore, by combining parameters such as the output frequency and vibration amplitude of the drive unit, the simulated mechanical properties of the human aorta can be adjusted to achieve the pressure parameters of postvalvular pressure and valve pressure differential during the closure phase that meet fatigue requirements, providing a more precise testing environment for artificial valves.

[0039] Furthermore, an exhaust valve is installed at the top of the bellows to facilitate the discharge of any gas that may be generated inside the bellows during the test, thus avoiding any adverse effects of gas on the test results, such as preventing inaccurate pressure measurements due to the presence of gas.

[0040] Furthermore, a drain pipe is provided, which is connected to the rodless chamber of the cylinder via a three-way pipe and equipped with a drain valve. This facilitates the drainage of liquid inside the equipment after the test or when the test liquid needs to be replaced, making the cleaning and maintenance of the equipment more convenient. It also helps to ensure the consistency of the liquid environment inside the equipment during each test, indirectly improving the accuracy of the test.

[0041] Furthermore, the artificial heart valve durability evaluation device of the present invention has significant technical effects in improving test accuracy, test convenience and flexibility, and equipment performance optimization, and can better meet the needs of accurately testing the fatigue life of artificial heart valves. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0043] Figure 1 This is a schematic diagram of the structure of an artificial heart valve durability evaluation device provided in one embodiment of the present invention;

[0044] Figure 2 This is a partial structural schematic diagram of an artificial heart valve durability evaluation device provided in one embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the structure of the pressure ring provided in one embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the voice coil motor control software interface provided in one embodiment of the present invention;

[0047] In the diagram: 1. Test platform; 2. Linear motor; 3. Slider; 4. Linear guide rail; 5. Coupling; 6. Piston rod; 7. Cylinder; 8. Inlet valve; 9. T-connector; 10. Drain pipe; 11. Dispensing container; 12. Bellows; 13. First connecting pipe; 14. Post-valve pressure sensor; 15. Pre-valve pressure sensor; 16. Quick-connect coupling; 17. Second connecting pipe; 18. Exhaust valve; 19. Drain valve; 20. Valve fixing mechanism; 21. Sleeve; 22. Support ring; 23. Pressure ring; 24. Insertion hole; 25. Bypass pipe; 26. Resistance valve. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The purpose of this invention is to provide an artificial heart valve durability evaluation device to solve the problems existing in the prior art and improve the accuracy of artificial heart valve fatigue life testing.

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] like Figures 1 to 3 As shown, this embodiment provides an artificial heart valve durability evaluation device, including:

[0053] Test platform 1;

[0054] The drive unit includes a linear motor 2 and a cylinder 7, which are respectively fixed on the test platform 1. The linear motor 2 is used to drive the piston rod 6 of the cylinder 7 to perform reciprocating linear motion. A liquid inlet valve 8 is provided on the side wall of the cylinder 7, which communicates with the rodless chamber of the cylinder 7.

[0055] Dispensing container 11 is connected to the rodless chamber of cylinder 7, and the top of dispensing container 11 is sealed.

[0056] Two test units are provided. Each test unit includes a bellows 12, a first connecting tube 13, a valve fixing mechanism 20, and a second connecting tube 17 connected from top to bottom. The bottom end of the second connecting tube 17 is connected to the top end of the dispensing container 11. The bottom end of the first connecting tube 13 and the top end of the second connecting tube 17 are detachably connected to the valve fixing mechanism 20. The valve fixing mechanism 20 is located at the top end of the second connecting tube 17 and is used to clamp the artificial heart valve to be tested. The bottom end of the bellows 12 is connected to the top end of the first connecting tube 13, and the top end of the bellows 12 is closed.

[0057] The measurement and control unit includes a controller, a pre-valve pressure sensor 15, and a post-valve pressure sensor 14. A linear motor 2, the pre-valve pressure sensor 15, and the post-valve pressure sensor 14 are respectively connected to the controller. A pre-valve pressure measuring port is provided on the second connecting pipe 17, and a post-valve pressure measuring port is provided on the first connecting pipe 13. The pre-valve pressure sensor 15 is installed on the pre-valve pressure measuring port, and the post-valve pressure sensor 14 is installed on the post-valve pressure measuring port. Each test unit also includes a bypass pipe 25, one end of which is connected to the first connecting pipe 13, and the other end is connected to the distribution container 11. A resistance valve 26 is provided on the bypass pipe 25. During the test, when the linear motor 2 drives the piston rod 6 of the cylinder 7 to move, causing the volume of the rodless chamber in the cylinder 7 to decrease, the liquid in the distribution container 11 will flow through the second connecting pipe 17, the artificial heart valve under test, and the first connecting pipe 13 into the bellows 12 (the artificial heart valve is equivalent to a one-way valve; in this embodiment, it is necessary to ensure that the direction of its guiding liquid flow is from the second connecting pipe 17 to the first connecting pipe 13). When the linear motor 2 drives the piston rod 6 of the cylinder 7 to move, causing the volume of the rodless chamber in the cylinder 7 to change from a decreasing state to an increasing state, the artificial heart valve under test will slowly change from an open state to a closed state. During the process, although some of the liquid in the bellows 12 and the first connecting pipe 13 will flow back to the distribution container 11 through the not-yet-fully-closed artificial heart valve under test and the second connecting pipe 17, once the artificial heart valve under test is closed, the liquid cannot return to the distribution container 11 through the artificial heart valve under test. Therefore, in reality, most of the liquid in the bellows 12 and the first connecting pipe 13 cannot flow back smoothly to the distribution container 11. Moreover, during the actual test, due to the high frequency of the reciprocating linear motion of the piston rod 6 of the cylinder 7 driven by the linear motor 2, the liquid in the distribution container 11 will gradually decrease over time, causing the test process to fail. This embodiment In this process, by setting a bypass pipe 25 to connect the first connecting pipe 13 and the distribution container 11, it is beneficial that when the volume of the rodless chamber in the cylinder 7 increases, the liquid in the bellows 12 and the first connecting pipe 13 flows back to the distribution container 11 through the bypass pipe 25, so that all the liquid in the bellows 12 and the first connecting pipe 13 can flow back to the distribution container 11, thereby ensuring the normal progress of the test process; and by adjusting the resistance valve 26, the backflow resistance can be adjusted, which is convenient to use; when the linear motor 2 drives the piston rod 6 of the cylinder 7 to move, causing the volume of the rodless chamber in the cylinder 7 to decrease, the artificial heart valve under test will open, and the liquid in the distribution container 11 can smoothly pass through the artificial heart valve under test.

[0058] In the drive unit, the linear motor 2 drives the piston rod 6 of the cylinder 7 to reciprocate linearly. At the same time, the side wall of the cylinder 7 is equipped with an inlet valve 8 that communicates with the rodless chamber, and the distribution container 11 is connected to the rodless chamber of the cylinder 7. These structures can create actual working conditions such as fluid pressure and flow that are closer to those inside the human heart during the test. This allows the artificial heart valve to be tested in an environment that is more in line with its actual use scenario, thereby improving the consistency between the test results and the actual situation, that is, improving the test accuracy.

[0059] During heartbeats, the human heart exerts periodic pressure changes on the heart valves. When the heart contracts, the higher pressure of blood on the valves forces them to open; when the heart relaxes, the pressure decreases, and the valves close. In this invention, the bellows 12, acting as a pressure storage component, can store and release pressure, thereby simulating a pulsating pressure environment similar to that within the body. For example, in a heart valve testing system, it can store pressure generated by the drive device at appropriate stages according to a set rhythm, and then release it at a suitable time, subjecting the valves to pressure changes similar to those experienced during a heartbeat in the human body, thus accurately testing the valve's fatigue performance under such complex pressure conditions.

[0060] It is worth noting that both the drive-related parameters of the drive unit and the related parameters of the bellows 12 (such as material, wave pitch, wave thickness, wave depth coefficient, etc.) should be fully tested so that the artificial heart valve durability evaluation device of this embodiment can simulate the aortic pressure waveform that conforms to the human body when it is working, thereby providing the accuracy of the test results.

[0061] The controller is connected to the linear motor 2, the prevalence pressure sensor 15, and the postvalence pressure sensor 14. The prevalence pressure sensor 15 and the postvalence pressure sensor 14 can monitor the pressure before and after the valve in real time and feed it back to the controller so that the test process can be precisely controlled according to the actual pressure data, ensuring that the test environment is closer to the real in vivo environment, thereby improving the test accuracy.

[0062] In the optional scheme of this embodiment, more preferably, the drive unit further includes a linear guide rail 4 fixed on the test platform 1 and a slider 3 that slides with the linear guide rail 4. The output end of the linear motor 2 is fixedly connected to the slider 3, and the slider 3 is fixedly connected to the piston rod 6 of the cylinder 7 through a coupling 5.

[0063] Linear guide rail 4 provides precise linear motion guidance for slider 3. In artificial heart valve durability testing equipment, when linear motor 2 drives slider 3, slider 3 can only move along the direction defined by linear guide rail 4, avoiding deviation in movement direction due to other external forces or its own structural reasons. This is crucial for accurately simulating the regular, linear opening and closing motion of heart valves in the body with the heartbeat. If the movement direction of the driving component deviates, the force and motion state transmitted to the artificial heart valve will also deviate, affecting the accuracy of the test results and failing to truly reflect the valve's operation under normal physiological conditions. Linear guide rail 4 typically has high manufacturing and installation precision, ensuring smooth and stable linear movement of slider 3 on its surface, reducing frictional resistance and vibration during movement. This low-friction, low-vibration motion characteristic helps improve the overall efficiency of the drive unit, while also extending the service life of related components and reducing the risk of component wear and failure due to friction and vibration.

[0064] In the optional solutions of this embodiment, a more preferred option is that the top end of the bellows 12 is also provided with an exhaust valve 18. The exhaust valve 18 is a one-way valve, which facilitates the discharge of gas in the bellows 12 through the exhaust valve 18 during the test, ensuring that the bellows 12 is completely filled with liquid and there is no gas, so as to avoid the adverse effects of gas on the test results, such as preventing inaccurate pressure measurement due to the presence of gas.

[0065] In the optional embodiments of this example, a more preferred option is to include a drain pipe 10. The dispensing container 11 is connected to the rodless chamber of the cylinder 7 via a three-way pipe 9. One port of the three-way pipe 9 is connected to the dispensing container 11, another port is connected to the rodless chamber of the cylinder 7, and yet another port is connected to one end of the drain pipe 10. A drain valve 19 is provided on the drain pipe 10. The drain pipe 10 and the drain valve 19 facilitate the drainage of liquid in the equipment after the test or when the test liquid needs to be replaced, making the cleaning and maintenance of the equipment more convenient. At the same time, it also helps to ensure the consistency of the liquid environment in the equipment during each test, indirectly improving the accuracy of the test.

[0066] In the optional schemes of this embodiment, it is more preferred that the linear motor 2 is a voice coil motor. The voice coil motor has the characteristics of fast response speed and high precision, which can more accurately drive the reciprocating motion of the piston rod 6 in the cylinder 7, thereby better simulating the regular movement of the heart valve in the body with the heartbeat, and ensuring the accuracy and stability of the test.

[0067] In the optional schemes of this embodiment, it is more preferred that the cylinder 7 is a rolling diaphragm cylinder. The rolling diaphragm cylinder has good sealing and stability during operation, which can effectively prevent gas or liquid leakage and ensure the stability of the test environment, thereby improving the accuracy and reliability of the test.

[0068] In the optional scheme of this embodiment, it is more preferred that the first connecting pipe 13 is connected to the second connecting pipe 17 through the quick-connect connector 16. This design allows for convenient and quick disassembly and replacement of components if a component malfunctions or if a different specification of artificial heart valve needs to be replaced during the test, without the need for large-scale disassembly and reassembly of the entire test equipment, thus improving the convenience of testing and the maintainability of the equipment.

[0069] In the optional embodiments of this example, the valve fixation mechanism 20 preferably includes a sleeve 21 and a pressure ring 23. The bottom of the sleeve 21 is inserted into the second connecting tube 17, and the outer wall of the sleeve 21 is bonded to the inner wall of the second connecting tube 17.

[0070] A support ring 22 is fixedly mounted on the inner wall of the sleeve 21, and a pressure ring 23 is threadedly connected to the inner wall of the sleeve 21. The pressure ring 23 is used to clamp the edge of the artificial heart valve to be tested in conjunction with the support ring 22. An insertion hole 24 is provided on the top surface of the pressure ring 23. The insertion hole 24 is provided so that the user can easily rotate the pressure ring 23 by inserting a screwdriver or other tools into the insertion hole 24. Both the sleeve 21 and the pressure ring 23 are made of metal.

[0071] Example 2

[0072] This embodiment provides a method for testing the fatigue life of artificial heart valves based on the aforementioned artificial heart valve durability evaluation equipment, including:

[0073] Through the inlet valve 8 on the side wall of cylinder 7, an appropriate amount of test liquid is injected into the rodless chamber of cylinder 7 and the distribution container 11 connected thereto, until the artificial heart valve durability evaluation device is filled with test liquid.

[0074] Based on the controller in the measurement and control unit, the motion parameters of the linear motor 2 are set; the motion parameters are used to determine the reciprocating motion law of the piston rod 6 in the cylinder 7; the piston rod 6 in the cylinder 7 is used to simulate the aortic pressure waveform of a set frequency through reciprocating motion; the linear motor 2 is a voice coil linear motor; the motion parameters include: initial motor position, voice coil motor point-to-point running position, motor stop position, voice coil motor periodic running waveform, voice coil motor periodic running amplitude, voice coil motor periodic running frequency, voice coil single-machine periodic running offset, and voice coil motor periodic running phase offset.

[0075] A segmented adjustment method is adopted to set the pressure thresholds of the prevalence pressure sensor 15 and postvalence pressure sensor 14 in the measurement and control unit. The pressure thresholds are used to monitor the pressure before and after the artificial heart valve. The segmented adjustment method is based on the PVT control mode. Initial pressure adjustment is performed. When the set threshold is reached, low-frequency cycle operation is started. When the fatigue pressure waveform that meets the high / low / average pressure of the low-frequency cycle is obtained, the operating frequency is increased and pressure adjustment continues until the set fatigue frequency is reached.

[0076] Start the linear motor 2 and acquire and record the pressure data before and after the artificial heart valve in the prevalence pressure sensor 15 and postvalence pressure sensor 14; the pressure data includes prevalence pressure and postvalence pressure.

[0077] Based on the pressure data before and after the artificial heart valve, the maximum prevalence pressure, average prevalence pressure, minimum prevalence pressure, maximum postvalence pressure, average postvalence pressure, minimum postvalence pressure, and peak transvalvular pressure gradient at valve closure are calculated within one opening and closing cycle.

[0078] According to the valve fatigue performance verification guidelines in the international standard ISO 5840, the maximum value, average value, minimum value, maximum value, average value, minimum value, and peak closure transvalvular pressure gradient of the artificial heart valve durability evaluation equipment are adjusted by setting the operating amplitude, frequency, offset, and phase offset of the voice coil motor.

[0079] The device monitors the maximum, average, minimum, maximum, average, minimum, and peak transvalvular pressure of the tested valve in the artificial heart valve durability evaluation equipment.

[0080] When the monitored postvalvular pressure and peak valve closure transvalvular pressure difference do not meet the valve fatigue performance verification guidelines in the international standard ISO 5840, the operating amplitude, frequency, offset, and phase offset of the voice coil motor are adjusted based on the PID adaptive algorithm until the postvalvular pressure and peak valve closure transvalvular pressure difference meet the valve fatigue performance verification guidelines in the international standard ISO 5840.

[0081] Specifically, in the artificial heart valve fatigue life testing process of this embodiment, the PID self-feedback phenomenon is closely related to the measurement and control unit. At the beginning of the test, the measurement and control unit will initially set the pressure thresholds of the prevalence pressure sensor 15 and the postvalence pressure sensor 14 according to a preset control strategy, such as the PVT control mode. These pressure thresholds are used to monitor the pressure conditions before and after the artificial heart valve to ensure that the valve works normally under simulated aortic pressure waveforms.

[0082] As the linear motor 2 is activated, the piston rod 6 begins to reciprocate, simulating the aortic pressure waveform at a set frequency. During this process, the measurement and control unit collects pre- and post-valve pressure data in real time and compares them with preset pressure thresholds.

[0083] When the actual pressure before or after the valve deviates from the preset threshold, the PID controller in the measurement and control unit will start to function. The PID controller will calculate the adjustment amount based on the deviation between the actual pressure and the set threshold, and correct this deviation by adjusting the motion parameters of the linear motor 2 or other control methods.

[0084] This adjustment process is a self-feedback process, because the measurement and control unit will continuously adjust the control strategy based on the real-time pressure data until the actual pressure stabilizes within the preset threshold range.

[0085] If, during actual testing, the PID self-feedback fails to effectively correct pressure deviations, this could be due to various reasons, such as a faulty valve, a faulty control unit, or an inappropriate control strategy. In this case, the testing personnel need to carefully inspect the testing equipment and methods to determine the root cause of the problem and take appropriate measures to resolve it.

[0086] Specifically, the usage process of the artificial heart valve durability evaluation equipment in this embodiment is as follows:

[0087] A suitable amount of test liquid is injected into the rodless chamber of cylinder 7 and related components such as the dispensing container 11 connected thereto through the liquid inlet valve 8 on the side wall of cylinder 7. Generally, a liquid simulating the characteristics of human blood, such as a liquid medium with specific viscosity and composition, can be used to better simulate the internal environment. During the injection process, the relevant components can be observed for leaks to ensure smooth liquid injection and a good system seal. Then, the liquid inlet valve 8 is closed.

[0088] The motion parameters of the linear motor 2, such as the frequency and amplitude of its reciprocating linear motion, are set through the controller of the measurement and control unit. These parameters determine the reciprocating motion pattern of the piston rod 6 in the cylinder 7, thereby affecting the flow and pressure changes of the liquid within the entire test unit to simulate the working environment of the artificial heart valve under different heartbeat frequencies and amplitudes. For example, the reciprocating motion frequency of the linear motor 2 can be set according to the normal human heartbeat frequency range, generally between 60-100 times / minute, or other frequency values ​​can be set according to specific test requirements. Simultaneously, parameters such as the start and stop times of the linear motor 2 can also be set to ensure that test operations are performed according to a predetermined test plan.

[0089] Appropriate pressure thresholds are set for the prevalence pressure sensor 15 and the postvalence pressure sensor 14. These thresholds will be used to monitor the pressure before and after the artificial heart valve. When the pressure exceeds or falls below the set threshold, the sensor will send a signal back to the controller so that the controller can make timely adjustments or record relevant data. For example, the thresholds can be set according to the pressure range before and after the aortic valve in a normal human body to accurately determine whether the artificial heart valve is in normal working condition and whether there are any abnormal pressure conditions during the test.

[0090] The linear motor 2 is activated by the controller of the measurement and control unit. The linear motor 2 drives the slider 3 to reciprocate linearly along the linear guide rail 4. The slider 3 drives the piston rod 6 of the cylinder 7 to reciprocate linearly through the coupling 5. As the piston rod 6 moves, the volume of the rodless chamber of the cylinder 7 changes, which in turn affects the liquid flow and pressure changes in the connected distribution container 11 and each test unit. When the piston rod 6 extends outward, the volume of the rodless chamber of the cylinder 7 increases, and the liquid pressure decreases; when the piston rod 6 retracts inward, the volume of the rodless chamber of the cylinder 7 decreases, and the liquid pressure increases. This creates a pulsating flow similar to that generated by the beating of a human heart within the test unit, which drives the artificial heart valve to open and close on the valve fixation mechanism 20.

[0091] In this embodiment, the linear motor 2 is selected as a linear voice coil motor driving the hydraulic cylinder as the power source for valve fatigue. When controlling the voice coil motor, different control modes need to be adopted according to changes in the actual application state. Valve fatigue begins when the drive motor starts running, and it takes a period of time after the valve opens and closes at high speed for the postvalvular reservoir to reach equilibrium. After prolonged operation, the valve's motion state changes, causing variations in the load.

[0092] This embodiment controls the voice coil linear motor to quickly reach the set pressure parameters under varying initial load conditions using a segmented adjustment method. Initially, using PVT control mode, the motor's initial position is adjusted to a suitable level. Then, low-frequency cyclic operation is initiated to obtain the fatigue pressure waveform that satisfies high / low / average pressure. The operating frequency is then increased, and the high / low / average pressure is readjusted until the set fatigue frequency is reached. During operation, if the pressure parameters exceed the set deviation, the reverse process is used: the operating frequency is reduced until the set pressure value is reached, and then the frequency is increased again. This upward control strategy effectively ensures rapid system setup and stable adjustment.

[0093] Specifically, regarding voice coil motor control:

[0094] The control of a voice coil motor mainly consists of a voice coil motor, a Copley motor driver, a CAN card, and a PC. Communication is via an RS-232 serial port and CANOpen. A serial-to-USB cable is used to connect the USB end to the computer and the serial end to the RS-232 port of the Copley digital servo motor driver.

[0095] A CAN-PCI card for CAN bus communication is inserted inside the computer chassis. The DB9 port of the CAN card is then connected to the CAN bus communication interface of the copley driver. The amplifier output of the driver is connected to the voice coil motor, and the optical encoder on the voice coil motor (used for position feedback during motor operation) is connected to the feedback signal input of the copley driver. When multiple voice coil motors need to be controlled, multiple copley motor drivers are connected to the CAN bus, with each driver driving one voice coil motor.

[0096] like Figure 4 As shown, the voice coil motor control software was developed using the C++Builder 5.0 platform and the software development kit (CMO.dll). CMO library introduction: The software development kit used for voice coil motor control is the CMO.dll (version 2.18) development tool provided by Copley. CMO.dll is packaged as a COM component, which can be used by all software development tools that support COM components.

[0097] Control mode used: The control program of the voice coil motor mainly uses the PVT control mode in the CMO library, that is, it continuously sends a series of points about position (P), speed (V), and time (T) to the RAM of the copley driver through CanOpen communication. When the motor completes its operation, it continues to send the next series of PVT point arrays, thus achieving the effect of uninterrupted cyclic operation of the motor.

[0098] The main functions of the voice coil motor control software include: initializing the motor position (Home), setting the point-to-point running position of the voice coil motor, setting the motor stop position, setting the periodic running waveform of the voice coil motor, setting the periodic running amplitude of the voice coil motor, setting the periodic running frequency of the voice coil motor, setting the periodic running offset of the voice coil motor, and setting the periodic running phase offset of the voice coil motor.

[0099] During testing, the prevalence pressure sensor 15 and postvalence pressure sensor 14 monitor the pressure before and after the artificial heart valve in real time and transmit the pressure data to the controller of the measurement and control unit. The controller determines whether the artificial heart valve is functioning normally and whether it has reached the set pressure threshold based on the received pressure data. For example, if the prevalence pressure exceeds the set threshold, it may indicate that the artificial heart valve is encountering resistance during opening, requiring further analysis; if the prevalence pressure is below the set threshold, it may indicate that the artificial heart valve is not opening completely or has a leak.

[0100] Specifically, the pre-valve pressure sensor 15 and the post-valve pressure sensor 14 can be ZXP610 type pressure sensors with a pressure range of 60KPa. Their main specifications are: model: ZXP 610, accuracy class: 0.15, nonlinearity: 0.15%FS, repeatability and hysteresis: 0.1%FS, output resistance: 5KΩ, insulation resistance >20MΩ / 50V, power supply: 6V, operating temperature: -10~70℃, and allowable overload: 1.5 times.

[0101] The pressure amplifier circuit uses a two-stage LM317 voltage regulator to provide a 6V regulated output, ensuring a 1.5A output current, a linear regulation of 0.01%, an 80dB ripple rejection ratio, output short-circuit protection, and overcurrent and overheat protection. This allows the 6V output to simultaneously power four sensors. The preamplifier uses an AD8221 precision instrumentation amplifier; the amplifier gain can be adjusted by changing resistor R5. The OPA2277 is a high-precision dual operational amplifier; the first stage is configured as a second-order low-pass filter, and the second stage is a non-inverting proportional amplifier. Adjusting potentiometer W1 allows for zero-point calibration of the sensors.

[0102] The USB data acquisition card uses the Advantech USB-4711A-AE model USB data acquisition board, whose main specifications are as follows: AD channels: 16SE / 8DI, resolution: 12bit, sampling rate: 150KS / s, on-board FIFO: 1024 samples (can hold 1024 sample values), input voltage range from +0.625V to +10V, accuracy from 0.4% to 0.1% (FSR), input impedance: 1GΩ; DA channels: 2, resolution: 12bit, output voltage range: unipolar 0~5V and 0~10V, bipolar +5V and +10V, accuracy +1LSB; digital I / O channels: 8 inputs and 8 outputs, counter: 1 channel.

[0103] This AD / DA board performs the conversion of pressure and temperature. Its resolution, accuracy, and conversion speed meet the requirements for analog signal acquisition.

[0104] During the test, the controller of the measurement and control unit continuously records the pressure data transmitted from the prevalence pressure sensor 15 and the postvalence pressure sensor 14, as well as the motion parameters of the linear motor 2 and other relevant information. This data will be organized into a format that is easy to analyze, such as tables and charts, so as to facilitate a comprehensive analysis of the fatigue life of the artificial heart valve.

[0105] Specifically, the selected control and measurement chassis used in the testing had a 12-channel pressure amplifier, a USB AD conversion module, a 2-channel voice coil motor driver, and a lighting power interface. The testing specifications were as follows: Number of tests: 6 stations; Testable types: mechanical valves, bioprosthetic valves, implantable valves; Testable valve sizes: valves 15-35; Operating frequency: 25-30Hz; Constant temperature: 37±1℃; Pressure conditions: Peak transmembrane pressure difference at aortic valve ≥100mmHg, duration ≥20% of the cycle; Observation / photography of valve opening and closing status; Recording of 10 cycles of pre- and post-valve pressure waveform data.

[0106] At a frequency of 30Hz, the valve status was observed, and normal opening and closing were recorded. Postvalvular pressure, prevalvular pressure, and postvalvular / prevalvular pressure gradient were measured. The maximum / average / minimum prevalvular pressure values ​​were 400 / 63 / -184 mmHg, and the maximum / average / minimum postvalvular pressure values ​​were 240 / 125 / 14 mmHg. The peak transmembrane pressure gradient at aortic valve closure was ≥100 mmHg for a duration >34% of the cycle. The system design objectives were achieved.

[0107] Based on the recorded pressure data, motion parameters, and other information, combined with the actual performance of the artificial heart valve during the testing process (such as whether the opening and closing action is normal, and whether abnormal wear occurs), the fatigue life of the artificial heart valve is assessed. For example, if the artificial heart valve shows significant wear or fails to open and close normally within a short period of time during the test, it may indicate a short fatigue life; if the artificial heart valve can still function normally after a longer period of testing, it may indicate a long fatigue life.

[0108] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An artificial heart valve durability evaluation device, characterized in that, include: Test platform; The drive unit includes a linear motor and a cylinder respectively fixed on the test platform. The linear motor is used to drive the piston rod of the cylinder to perform reciprocating linear motion. A liquid inlet valve communicating with the rodless chamber of the cylinder is provided on the side wall of the cylinder. A dispensing container, which is connected to the rodless chamber of the cylinder, and the top of the dispensing container is sealed; The system comprises several test units, each including, from top to bottom, a corrugated tube, a first connecting tube, a valve fixing mechanism, and a second connecting tube. The bottom end of the second connecting tube is connected to the top end of the dispensing container. The bottom end of the first connecting tube is detachably connected to the top end of the second connecting tube. The valve fixing mechanism is located at the top end of the second connecting tube and is used to clamp the artificial heart valve to be tested. The bottom end of the corrugated tube is connected to the top end of the first connecting tube, and the top end of the corrugated tube is closed. Each test unit also includes a bypass tube, one end of which is connected to the first connecting tube and the other end of which is connected to the dispensing container. A resistance valve is provided on the bypass tube. The measurement and control unit includes a controller, an inverted pressure sensor, and a post-valve pressure sensor. The linear motor, the inverted pressure sensor, and the post-valve pressure sensor are respectively connected to the controller via signals. A pre-valve pressure measuring port communicating with the second connecting pipe is provided on the second connecting pipe, and a post-valve pressure measuring port communicating with the first connecting pipe is provided on the first connecting pipe. The inverted pressure sensor is installed on the pre-valve pressure measuring port, and the post-valve pressure sensor is installed on the post-valve pressure measuring port.

2. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The drive unit also includes a linear guide rail fixed on the test platform and a slider that slides with the linear guide rail. The output end of the linear motor is fixedly connected to the slider, and the slider is fixedly connected to the piston rod of the cylinder through a coupling.

3. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The top of the bellows is also equipped with an exhaust valve, which is a one-way valve, and the bellows is sealed. During the operation of the artificial heart valve durability evaluation equipment, the bellows is filled with liquid to expel all the gas in the bellows. The pressure is stored through the elastic deformation of the bellows. Compared with using air as a medium for temporary pressure storage, the bellows has a faster response speed.

4. The artificial heart valve durability evaluation device according to claim 1, characterized in that: It also includes a drain pipe. The dispensing container is connected to the rodless chamber of the cylinder via a three-way pipe. One port of the three-way pipe is connected to the dispensing container, another port is connected to the rodless chamber of the cylinder, and yet another port is connected to one end of the drain pipe. A drain valve is provided on the drain pipe.

5. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The linear motor is a voice coil motor.

6. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The cylinder is a rolling diaphragm cylinder.

7. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The first connecting pipe is connected to the second connecting pipe via a quick-connect fitting.

8. The artificial heart valve durability evaluation device according to claim 1, characterized in that: The valve fixation mechanism includes a sleeve and a pressure ring. The sleeve is partially inserted into the second connecting tube, and the outer wall of the sleeve is bonded to the inner wall of the second connecting tube. A support ring is fixed on the inner wall of the sleeve, and a pressure ring is threadedly connected to the inner wall of the sleeve. The pressure ring is used to cooperate with the support ring to clamp the edge of the artificial heart valve to be tested.

9. The artificial heart valve durability evaluation device according to claim 8, characterized in that: A socket is provided on the top surface of the pressure ring for inserting a screwdriver.

10. A method for testing the fatigue life of an artificial heart valve based on the artificial heart valve durability evaluation device according to any one of claims 1-9, characterized in that, include: Through the inlet valve on the side wall of the cylinder, an appropriate amount of test liquid is injected into the rodless chamber of the cylinder and the distribution container connected thereto, until the artificial heart valve durability evaluation device is filled with test liquid. Based on the controller in the measurement and control unit, the motion parameters of the linear motor are set; the motion parameters are used to determine the reciprocating motion law of the piston rod in the cylinder; The piston rod in the cylinder is used to simulate aortic pressure waveforms at a set frequency through reciprocating motion. The linear motor is a voice coil linear motor; the motion parameters include: initial motor position, voice coil motor point-to-point running position, motor stop position, voice coil motor periodic running waveform, voice coil motor periodic running amplitude, voice coil motor periodic running frequency, voice coil single-machine periodic running offset, and voice coil motor periodic running phase offset. A segmented adjustment method is adopted to set the pressure thresholds of the prevalvular pressure sensor and the postvalvular pressure sensor in the measurement and control unit. The pressure thresholds are used to monitor the pressure before and after the artificial heart valve. The segmented adjustment method is based on the PVT control mode. Initial pressure adjustment is performed. When the set threshold is reached, low-frequency cycle operation is started. When the fatigue pressure waveform that meets the high / low / average pressure of the low-frequency cycle is obtained, the operating frequency is increased and pressure adjustment continues until the set fatigue frequency is reached. Start the linear motor and acquire and record the pressure data before and after the artificial heart valve in the prevalvular pressure sensor and postvalvular pressure sensor; the pressure data includes prevalvular pressure and postvalvular pressure. Based on the pressure data before and after the artificial heart valve, the maximum prevalence pressure, average prevalence pressure, minimum prevalence pressure, maximum postvalence pressure, average postvalence pressure, minimum postvalence pressure, and peak transvalvular pressure gradient at valve closure are calculated within one opening and closing cycle. According to the valve fatigue performance verification guidelines in the international standard ISO 5840, the maximum value, average value, minimum value, maximum value, average value, minimum value, and peak closure transvalvular pressure gradient of the artificial heart valve durability evaluation equipment are adjusted by setting the operating amplitude, frequency, offset, and phase offset of the voice coil motor. The device monitors the maximum, average, minimum, maximum, average, minimum, and peak transvalvular pressure of the tested valve in the artificial heart valve durability evaluation equipment. When the monitored postvalvular pressure and peak valve closure transvalvular pressure difference do not meet the valve fatigue performance verification guidelines in the international standard ISO 5840, the operating amplitude, frequency, offset, and phase offset of the voice coil motor are adjusted based on the PID adaptive algorithm until the postvalvular pressure and peak valve closure transvalvular pressure difference meet the valve fatigue performance verification guidelines in the international standard ISO 5840.

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