SU1577782A1 - Device for examining artificial heart valves - Google Patents

Abstract

The invention relates to medical technology and can be used to test artificial heart valves. The purpose of the invention is to improve the accuracy of measuring the hydrodynamic parameters of valves by bringing the test conditions to natural while reducing the test time. The device contains two opposed pistons 3 and 4 connected by a string 9, a shunt channel 2 with a check valve 10, a test chamber 11 with the test valve 15, pressure sensors 25, 26, an instantaneous flow sensor in the form of a potentiometer 41, kinematically connected with one of the pistons, reference water manometer 23, buffer 16 and storage tank 21, pneumatic pump 19, hydraulic valves 18, 22, automatic calibration unit 24, pressure automatic machine 42, hydraulic drive motor speed control unit 32 and electromechanical transmission d 28 containing the sine mechanism allowing to vary the stroke volume value from zero to constructively predetermined value during operation of the device. The device measures the pressure drop across the test valve and the instantaneous flow through it. The entire valve test cycle is performed automatically, including hydrodynamic information processing, which is printed in the form of a standard protocol and graphs. 2 hp f-ly, 5 ill.

Description

The invention relates to medical technology and can be used to test prosthetic heart valves.

The purpose of the invention is to improve the accuracy of measuring the hydrodynamic parameters of valves by bringing the test conditions to natural while reducing the test time.

FIG. 1 shows a diagram of a device for testing artificial heart valves; in fig. 2 is a kinematic diagram of an electromechanical drive; in fig. 3 is a block diagram of the automatic calibration panel; in fig. 4 is a pressure automatic circuit diagram; in fig. 5 is a block diagram of the rotational speed motor control unit.

The device for testing artificial heart valves contains opposed pistons 3 and 4 located at the ends of housing 1 with shunt channel 2, which are working elements. The pistons 20 are sealed with tubular sleeves 5 and 6, each of which is fixed at one end on a corresponding piston, and the other i: a are displaced liners of piston groups 7 and 8. The pressure machine 42 is electrically connected to the automatic calibration unit 24, the pneumatic pump 19 and the electromechanical drive 28.

- The automatic calibration block contains an amplifier 43 for indicating the levels of a gauge 23. The inputs of these amplifiers are connected to the contact groups of the gauge, and the outputs with light indicators 44 and digital inputs of a computer.

Differential amplifiers 45, 46, 47 are amplifiers for pressure and flow conversion channels. The input of these amplifiers includes electrical sensors 25 and 26, as well as displacement sensors 41, the outputs of the amplifiers are connected to arrow indicators 48-50 signal levels and computer inputs. In addition, the output of amplifier 46 is connected to a pressure circuit breaker 42.

The pressure machine 42 contains two electromagnetic relays 51 and 52. The winding of the relay 51 is connected via an adjustable additional resistance 53 to the output of a differential amplifier 46. The winding of the relay 52 is bounded by a capacitor 54 and is connected at one end to the output of a 15

fixed to the housing 1. Pistons 3 and 4 „of the potential amplifier 46, and the other with the common end of the switching contact of the same relay. Normally closed and normally open contacts of the relay through adjustable additional resistances 55 and 56 are connected to the output differentiated by a string 9 passing inside shunt channel 2. In the same channel a spring-loaded non-return valve 10 is installed. Case 1 contains a test chamber 11 inside which between two transparent coaxial zonal amplifiers 46. Normally, the short tubes 12 and 13 inserted into the third tube coaxially located the third tube 14, the cuff clamped, which forms the attachment point of the test valve 15. The calibration apparatus comprises a buffer emty relay contact 51 is connected to the mains power supply conductor and a common end of the second contact group relay 52. The normally open contact of this group is connected to a pneumatic pump, and a normally closed

40

The bone 16 with the separation membrane 17, 35 is in contact with the control unit 32 which is coaxed through the hydraulic valve 18 with the rotational shunt of the electric motor by the hydraulic channel 2, the pneumopump 19, the coupled drive.

flow through the gas-jet jet 20Block 32 of the speed control unit

cumulative capacity 21, the hydraulic cavity of which is connected through a hydraulic valve 22 with a shunt channel 2, a reference pressure gauge 23 with contact groups and an automatic calibration unit 24. The pressure sensors 25 and 26 are electrically connected to the automatic calibration unit 24 and mounted on the housing 1. The piston 3 (the 45 thyristor electrodes are connected to the right circuit) via the rod 27 with a computer kinemator.

The hydraulic motor contains a DC power source 57 connected in series with the rotor winding of the motor 30 and a group of parallel-connected ballasts 58, each of which is connected in series with the thyristor 59, and the control

0

movement. The pressure machine 42 is electrically connected to the automatic calibration unit 24, the pneumatic pump 19 and the electromechanical drive 28.

The automatic calibration unit contains an amplifier 43 for indicating the levels of a gauge 23. The inputs of these amplifiers are connected to the contact groups of the gauge, and the outputs with light indicators 44 and digital computer inputs.

The differential amplifiers 45, 46, 47 are amplifiers for the pressure and flow conversion channels. The input of these amplifiers includes electrical sensors 25 and 26, as well as displacement sensors 41, the outputs of the amplifiers are connected to arrow indicators 48-50 signal levels and computer inputs. In addition, the output of amplifier 46 is connected to a pressure circuit breaker 42.

The pressure machine 42 contains two electromagnetic relays 51 and 52. The winding of the relay 51 is connected via an adjustable additional resistance 53 to the output of a differential amplifier 46. The winding of the relay 52 is bounded by a capacitor 54 and is connected at one end to the output of

The potential amplifier 46, and the other with the common end of the switching contact of the same relay. Normally closed and normally open contacts of the relay through adjustable additional resistances 55 and 56 are connected to the output. Differential contact of relay 51 is connected to the mains power supply wire and the common end of the second contact group of relay 52. Normally open contact of this group is connected to the pneumatic pump, and normally closed

the contact is with the control unit 32 of the rotational speed of the hydraulic motor.

thyristor electrodes are connected to a computer commutator.

The hydraulic motor contains a DC power source 57 connected in series with the rotor winding of the motor 30 and a group of parallel-connected ballasts 58, each of which is connected in series with the thyristor 59, and the control

is mechanically connected with an electromechanical actuator 28 comprising a housing 29, an electric motor 30 electrically connected through time relay contacts 31 to a block 32

The device works as follows.

After pressing the start button on the automatic calibration block 24, it is turned on and controlled by the speed of its rotation. The electro-50 windings of the hydraulic valves 18 are blocked; the rotor 30 is kinematically connected to the bar- and 22, which are connected to the shunt

a ban 33 in which a conical solar wheel 34 is mounted with the possibility of axial movement with the aid of a clamp 35, a conical satellite 36 which, via a worm gear 37, is connected with a disk 38, 55 equipped with a lead 39 connected to the slide 40 of the sinus mechanism. With the actuator stem 27, a sensor 41 is kinematically coupled.

channel 2 buffer tank 16 and storage tank 21. At the same time, the pneumatic pump 19 is connected, connected through the jet 20 to the storage tank 21. During operation of the pneumatic pump 19, the pressure in the air chamber of the storage tank 21 slowly increases. The rate of increase in pressure is determined by the resistance of the liquid channel 2 buffer tank 16 and the storage tank 21. At the same time, the pneumatic pump 19 connected via the jet 20 to the storage tank 21 is turned on. When the pneumatic pump 19 is operating, the pressure in the air chamber of the storage tank 21 slowly increases. The rate of increase in pressure is determined by the resistance of the nozzle 20 and is adjusted so that the increase and decrease take place within 1.5-2 minutes. This is necessary to eliminate dynamic effects in the hydraulic system, which may be the cause of errors in the calibration of pressure sensors. Since the storage tank 21 is connected to the cavity of the housing 1 and to the buffer tank 16 of the reference water pressure gauge 23, the pressure in the housing 1 and the buffer tank 16 also increases. As the pressure is increased, the fluid in the accumulation tank 21 through the shunting channel 2 fills the lower part of the buffer tank 16 and displaces the electrically conductive

23) and turns on the pneumatic pump 19. When the pneumatic pump 19 operates, the pressure in the device body increases, the pistons 3 and 4 move apart, and the string 9 is pulled up. When the pressure in the stand reaches a predetermined value, the signal from the pressure sensor 25 through the automatic calibration unit 24 turns off the hydraulic valve 22 The storage tank 21 from the inner cavity of the compartment, through the automatic machine 42, turns off the pneumopump 19 and turns on the electric motor of the drive 28.

The motor 30 rotates the drum 33 through the transmission. When the drum 33 is rotated, the leash 39 mounted on the disk 38,

the fluid that is separated from the fluid 15 moves the slide 40 of the sine mechanism located in the housing, which is connected with the piston rod 27 of the piston 3.

membrane 17. The displaced liquid is filled-when the sun wheel 34 is coupled to the sleigh of the tube of the reference pressure gauge 23, the co-tell 36 and the drum 33 rotates, holding the electrical contact corpse-tellite 36 over the stationary solar

py located on its wall. When the pressure wheel is 34 and through the worm gear 37

The magnitude of the increase in the column of liquid 20 turns the disk 38 with a leash of 39 arms in the reference pressure gauge 23 will raise the circle of its axis. The position of the driver 39 relative to the axis of rotation of the drum 33 is constantly changing (the radius of rotation of the driver 39 changes relative to

to the limit, a predetermined mark, closes his last contact. The signal from turning on this contact goes to

automatic calibration block 24, which 25 axes of rotation of the drum 33). Law of motion

on the pneumatic pump 19 issues the command “Stop. After stopping the pneumopump 19, the liquid column of the manometer slowly (within 1.5-2 minutes) sinks, squeezing the working fluid through the hydraulic valves 18 and 22 into the accumulation tank 21. The time 30 of the pressure drop (from maximum to zero) is determined by the resistance of the orifice 20 and is selected such that the process of pressure change can be considered static. The liquid column descending in the manometer sequentially disconnects the contacts of the reference levels. The switching-off pulses through the automatic calibration unit 24 enter the computer, into which the electric potentials proportional to the pressure inside the device case are also continuously transmitted through the calibration unit from the pressure sensors 25 and 26. At the moment the level contact is disconnected (which corresponds to the pressure of a liquid column of a certain height), the computer registers and remembers the potential value of the corresponding pressure sensor and assigns this potential a pressure value equal to the reference level. The reference manometer 23 contains several predetermined levels (there are 20 levels in the described gauge). Thus, pressure sensors 25 and 26 are calibrated at 50 points by 20 points, which allows calibration of pressure channels and taking into account non-linearity of pressure channels.

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The piston in such a motion is described by the following expression

L 2Rcosjf (-cosQt),

where L. is the movement of the piston;

R is the distance between the axes of the drum

and disk;

Q is the angular velocity of rotation of the drum;

i - gear ratio from drum to disk.

As can be seen from expression (1), the amplitude of oscillation of the piston varies according to a harmonic law, determined by the cosQt member, and modulated by a long-period oscillation determined by the cos-

Cl t

Thus, the drive mechanisms form the hydrodynamic oscillations of the piston with a frequency O, and the amplitude of the piston movement in each subsequent

- Ј cycle with frequency.

2.1

In the developed drive, the hollow cycle changes in amplitude from 0 to 2R, where R is the distance between the axes of the drum and the disk occurs in 25 cycles of motion of the piston.

After the liquid column has lowered to the last lower contact, a signal about its opening will go to the automatic calibration unit 24, turn off the hydraulic valve 18 (turning off the reference pressure gauge 23) and turn on the pneumatic pump 19. When the pneumatic pump 19 operates, the pressure in the device case increases, the pistons 3 and 4 when the pressure in the test bench reaches a predetermined value, the signal from the pressure sensor 25 through the automatic calibration unit 24 turns off the hydraulic valve 22, the storage chamber 21 from the internal cavity Twa machine 42 through a pneumatic pressure off 19 and includes drive motor 28.

The motor 30 rotates the drum 33 through the transmission. When the drum 33 is rotated, the leash 39 mounted on the disk 38,

The piston in such a motion is described by the following expression

L 2Rcosjf (-cosQt),

where L. is the movement of the piston;

R is the distance between the axes of the drum

and disk;

Q is the angular velocity of rotation of the drum;

i - gear ratio from drum to disk.

As can be seen from expression (1), the amplitude of oscillation of the piston varies according to a harmonic law, determined by the cosQt member, and modulated by a long-period oscillation determined by the cos-

Cl t

Thus, the drive mechanisms form hydrodynamic oscillations of the piston with a frequency O, with the amplitude of the piston moving in each subsequent

- Ј cycle with frequency.

2.1

In the developed drive, the hollow cycle changes in amplitude from 0 to 2R, where R is the distance between the axes of the drum and the disk occurs in 25 cycles of motion of the piston.

If, with a rotating (or stationary) drum 33, the satellite 36 with the sun wheel 34 is opened by axially displacing the satellite 36 with the help of a lock 35, then the described mechanism located inside the drum 33 will cease

work and due to the self-braking property of the worm gearbox 37, the rotation radius of the driver 39 relative to the axis of the drum 33 will remain unchanged. This drive condition provides the pressure of the piston 3 with a constant amplitude according to the law

(- cosQt) where.

Thus, the electromechanical actuator 28 has two modes of operation. The first mode provides a gradual change in the amplitude of the piston movement, and therefore, for a given section of the piston, the impact surge from zero to the structurally specified maximum value and again to zero. The amplitude change is repeated with a long period. In the developed drive, the period of change of impact surge is 25 times longer than the period of movement of the piston. The second mode provides the drive with a constant shock output.

The drive allows you to vary the shock output in the range from 0 to 4RS, where S is the cross section of the piston, during operation of the device by opening the sun wheel 34 with the satellite 36 at the right time.

When the drive is operated in any of the modes, after the motor 30 is turned on, the piston 3 connected to the drive shaft 27 begins to move. Moving the piston in the direction shown in (Fig. 1) by arrow I leads to the flow of fluid in housing 1. The fluid flows through the test chamber 11 with the test valve 15 and fills the space at the piston 4. At the same time, the fluid flows through the shunt channel 2 is impossible, since such a flow is prevented by a check valve 10. The synchronous movement of both pistons 3 and 4 is ensured by the transfer of pressure through the fluid. After the end of the movement phase of the pistons in the I direction, the force applied to the piston 3 from the drive side changes sign, the piston 3 begins to move in the direction shown in (Fig. 1) by arrow II, and through the string 9 (and not due to vacuum) draws the piston 4. In the same direction, the fluid begins to move. While the test valve 15 is not closed, the fluid flows through the test chamber AND, since the valve 10 is spring-loaded and when the valve 15 is open, the pressure in the shunt channel 2 is not enough to open the valve 10. The liquid flow through the test chamber 11 when the valve 15 is closed simulates regurgitation. After closing the valve 15, the pressure in the housing 1 increases, the valve 10 opens and fluid begins to flow through the shunt channel 2 into the space at the piston 3 until the movement of the piston 3 in direction II ends. Then the cycle is repeated.

Simultaneously with the start of operation of the electric motor 30, the relay 31 connected to the stator winding of the electric motor 30 is turned on, and the time begins to count. In the manufactured device used electromechanical relay EMRV-27-1.

During operation, the device continuously measures two pressure sensors 25 and 26 connected through the automatic calibration console 24 to the computer input, and measures the pressure drop across the test valve 15. Simultaneously, the voltage read from the position sensor 41 is measured, which is proportional to the instantaneous flow function in the highway device. This voltage is also fed to the computer via the automatic calibration block. The information supplied to the computer is processed, printed out in the form of a standard test report and graphs.

After the time delay required for retrieving information, the time relay 31 shuts off the motor 30. At this, the test cycle ends and the device is ready for the next start.

In order to protect the elements of the device from pressure overload, a pressure machine 42 (Fig. 4) is used that is electrically connected via an automatic calibration panel 24 to an electro-manometer. The automatic machine shuts off the motor 30 of the drive if the pressure in the housing 1 is below or above the specified threshold values. For this purpose, the pressure machine 42 contains two electromagnetic relays 51 and 52, the response and release voltage of which is regulated by means of additional resistances 53, 55, 56. If the pressure in the system is normal, then the voltage at the input of the pressure automat (points a and The "b" circuit of Fig. 4) coming from the pressure sensor 25 through the automatic calibration console 24 is not enough to trigger the relay 51. In this mode, the relay 51 is in the state shown in FIG. 4. If the pressure in the system is below normal, the voltage at the points a and b of the circuit will not be sufficient to keep the relay 52 in the tightened state and the contact to P2 / i switches to resistance 55. At the same time, contacts k through the unit 32, the circuit of the electric motor 30 is opened, the pneumatic pump 19 and the hydraulic valve 22 are turned on. Due to the operation of the pneumatic pump 19, the pressure in the system is restored and, when it reaches the norm, the relay 52 switches to the initial state indicated in FIG. 4. Capacitor 54 is needed to eliminate chattering of relay 52 at the time of switching contacts to the RC. When the system pressure is above the threshold value (which may be a consequence of device malfunction), relay 51 is triggered, opening is opened with contacts k, P of pneumatic pump 19 and electric motor 30. Electromechanical actuator 28 stops and will start after the fault has been eliminated.

To change the rotational speed of the motor 30 of the drive, which determines the frequency of the test of the valve 15 (pulse), the device contains a unit 32 controlling the speed of rotation of the engine (Fig. 5). The change in speed is achieved by the inclusion of the ballasts 58 in the rotor circuit of the electric motor 30. The ballasts are switched on by the thyristors 59 by applying a signal from the computer switch to the control electrode of the corresponding thyristor. The thyristors are turned off by briefly disconnecting the DC power source 57 using a computer switch.

The elastic tubular cuffs 5 and 6 (Fig. 1) completely seal the device, allowing the translational movement of the pistons 3 and 4. Each of the cuffs is fixed on the corresponding piston — with one end covering it in diameter, and —other on the housing 1 (on the piston sleeve group), also covering it in diameter. Cuffs 5 and 6 are tightly pressed against the piston of the sleeve by a bandage. With an increase in pressure in the housing 1, the cuffs 5 and 6 are straightened, forming toroidal corrugations, which, when the pistons 3 and 4 move, roll over the piston and the sleeve, without creating a sliding friction.

The work of the reference pressure gauge 23 is based on the closing and opening of contact groups located on its inner wall, when the liquid comes into contact with the contacts. Distilled water or a mixture of water with glycerin, which is usually poured into the case of the device, has a high electrical resistance, therefore, in order to obtain an acceptable current for the amplifier, through the contact group of the pressure gauge 23 (Fig. 1) it is necessary to increase the voltage applied to the contacts. This leads to the release of gas on the electrodes due to the electrolysis of water and sometimes leads to false positives of the contact groups. In the proposed technical solution, the reference manometer 23 is filled with electrolyte, which reduces the electrical resistance of the liquid and allows the voltage on the contact groups to be reduced to a value less than the water decomposition potential. The separation membrane 17 serves to separate the liquid media contained in the device body and in the pressure gauge 23.

Claims (3)

1. Device for testing artificial heart valves, comprising a housing with a working fluid and a working element a volume, a test chamber with a fixture for an artificial valve, a shunt channel with a check valve, an electromechanical actuator, characterized in that 5 in order to increase the reliability of the measurement results of the valve’s hydrodynamic parameters by approximating the test conditions to natural and reducing the test time, it contains a storage tank with hydraulic and pneumatic belts, a pressure machine, an automatic calibration unit, a control unit, a pneumatic pump, a reference pressure gauge with contact groups, time relays, pressure sensors, hydraulic valves and the second working 5, a piston element, which is kinematically connected with the first element, made in the form of a piston, and a displacement sensor; the pistons are fitted with elastic tubular cuffs so that one end of each cuff is fixed on the corresponding piston and the other on the body; the drive contains a sinus mechanism with a link, a catch on which a conical solar wheel is installed with the possibility of axial 5 movement and kinematically connected with a conical satellite installed in the drum and connected through a worm gear with a disk carrying a leash connected to the slide of the sinus mechanism, the disk is located eccentrically relative to 0 axis of the drum at a distance equal to the shoulder of the driver, the reference pressure gauge, the first hydraulic valve, the shunt channel, the second hydraulic valve and the liquid cavity of the storage tank are connected in series, and the gas cavity is accumulative 5, the container is pneumatically connected via a jet to a pneumatic pump, the fixture of an artificial valve consists of two coaxial tubes coaxially located in the third tube, an automatic calibration unit, the inputs of which are connected to the contact groups of the reference pressure gauge, pressure and displacement sensors, the outlets are connected to the pneumatic pump, and hydraulic valves and a pressure automatic machine, the outputs of which are connected to a pneumatic pump and an electromechanical actuator, which through a time relay is connected to a control unit, whose input is with an input device, one of the outputs of the automatic calibration block is the output device. 2. The device according to claim 1, characterized in that it is provided with a buffer tank with an elastic membrane dividing it into two cavities and connected between a reference pressure gauge and the first hydrovalve, the cavity of the buffer tank connected to the reference pressure gauge, and the pressure gauge itself filled with electrolyte. 3. A device according to claim 1, characterized in that the pistons are located oppositely and are interconnected by a string passing through the shunt channel. five  27 39 40 38 33 36 FIG. 2 From 6 but 56 / Sj0  SB 59 Kpi SHIGA