METHOD AND DEVICE FOR DETECTING A WEAR CONDITION OF A VENTRICULAR ASSIST DEVICE AND FOR OPERATING SAME, AND VENTRICULAR ASSIST DEVICE

Abstract

The invention relates to a method for detecting a state of wear of a cardiac support system. The method comprises a read-in step and a determination step. During the read-in step, a sensor signal (315) representing an operating state of the cardiac support system is read in. During the determination step, a wear signal (325) is determined using the sensor signal (315) and a comparison rule (320). The wear signal (325) represents the wear condition.

Claims

1.-13. (canceled)

14. A method for detecting a state of wear of a cardiac support system, the method comprising: receiving a first sensor signal, the first sensor signal associated with a first operating state associated with an impeller of a cardiac support system; receiving a second sensor signal, the second sensor signal associated with a second operating state of the cardiac support system; and determining a wear signal based at least in part on the first sensor signal, the second sensor signal, and a comparison rule, wherein the wear signal is associated with the state of wear of the cardiac support system.

15. The method of claim 14, wherein the first sensor signal is associated with deposits on the impeller or an imbalance of the impeller.

16. The method of claim 14, wherein the first sensor signal is associated with at least one of: position, vibration, acceleration, pressure, rotation rate, temperature, voltage, current, power, optical reflection, or electrical resistance associated with the impeller.

17. The method of claim 14, wherein the second sensor signal is associated with an inlet cannula of the cardiac support system.

18. The method of claim 17, wherein the second sensor signal is associated with a change in flow or pressure in the inlet cannula.

19. The method of claim 14 further comprising: providing the first sensor signal or the wear signal to an external processing device.

20. The method of claim 14, wherein the first sensor signal represents the operating state of the cardiac support system in the time domain or the frequency domain.

21. The method of claim 14 further comprising: determining a characteristic oscillation in changes of the first operating state of the cardiac support system, and wherein the characteristic oscillation is associated with an error pattern of the first operating state.

22. The method of claim 14, further comprising determining the comparison rule based at least in part on the first sensor signal.

23. The method of claim 14 further comprising: generating a fingerprint based at least in part on the first sensor signal; comparing the fingerprint with a healthy fingerprint based at least in part on the comparison rule; and determining the wear signal based at least in part on the comparison between the fingerprint and the healthy fingerprint.

24. The method of claim 14 further comprising: generating a control signal configured to control a component of the cardiac support system, the control signal generated based at least in part on the wear signal; and transmitting the control signal for controlling a component of the cardiac support system.

25. A system configured to determine a state of wear of a cardiac support system, the system comprising: a reading device configured to receive a first sensor signal associated with a first operating state of an impeller of a cardiac support system and a second sensor signal associated with a second operating state of the cardiac support system; and a determination device configured to determine a wear signal based at least in part on the first sensor signal, the second sensor signal, and a comparison rule.

26. The system of claim 25 further comprising: a control device configured to generate and transmit a control signal to the cardiac support system, wherein the control signal is configured to control a component of the cardiac support system, and wherein the control signal is generated based at least in part on the wear signal.

27. The system of claim 25, wherein the first sensor signal is associated with an impeller of the cardiac support system.

28. The system of claim 25, wherein the first sensor signal represents the operating state of the cardiac support system in the time domain or the frequency domain.

29. The system of claim 25, wherein the second sensor signal is associated with an inlet cannula of the cardiac support system.

30. A cardiac support system comprising: an inlet cannula for delivering blood volume flow to a flow pump; an impeller of the flow pump; and a device configured to determine a state of wear of a cardiac support system, the device comprising: a reading device configured to receive a first sensor signal associated with a first operating state of the impeller of the cardiac support system and a second sensor signal associated with a second operating state of the cardiac support system; and a determination device configured to determine a wear signal based at least in part on the first sensor signal, the second sensor signal, and a comparison rule; and a control device configured to generate and transmit a control signal to the cardiac support system, wherein the control signal is configured to control a component of the cardiac support system, and wherein the control signal is generated based at least in part on the wear signal.

31. The system of claim 30, wherein the first sensor signal is associated with an operating state of the impeller of the cardiac support system.

32. The system of claim 30, wherein the first sensor signal represents the operating state of the cardiac support system in the time domain or the frequency domain.

33. The system of claim 30, wherein the second sensor signal is associated with an operating state of the inlet cannula of the cardiac support system.

Description

[0022] Design examples of the approach presented here are shown schematically in the drawings and explained in more detail in the following description. The figures show:

[0023] FIG. 1 a schematic illustration of a cardiac support system in aortic valve position according to one design example;

[0024] FIG. 2 a schematic illustration of an apical cardiac support system according to one design example;

[0025] FIG. 3 a schematic illustration of a device for detecting a state of wear of a cardiac support system according to one design example;

[0026] FIG. 4 a schematic illustration of a device for operating a cardiac support system according to one design example;

[0027] FIG. 5 a schematic illustration of an arrangement of sensors of a cardiac support system with a device for detecting a state of wear of a cardiac support system according to one design example; and

[0028] FIG. 6 a flow diagram of a method for detecting a state of wear of a cardiac support system and a method for operating a cardiac support system according to one design example.

[0029] In the following description of favorable design examples of the present invention, the same or similar reference signs are used for the elements shown in the various figures, which have a similar effect, whereby a repeated description of these elements is omitted.

[0030] FIG. 1 shows a schematic illustration of a cardiac support system 100 in aortic valve position according to one design example. The figure shows a simple illustration of the cardiac support system 100 in the implanted state in a heart 105. In the aortic valve position of the cardiac support system 100 shown here, a section of the cardiac support system 100 with an inlet cannula 110 is disposed in the left ventricle 115 of the heart 105, and another section of the cardiac support system 100 is disposed in the aorta 120 in the region of the aortic valves 125. A pump volume flow 130 is received at the tip of the inlet cannula 110 in the ventricle 115 and discharged in the region of the aorta 120. One design example of the cardiac support system 100 shown here comprises a device for detecting a state of wear or for operating the cardiac support system 100, as shown with reference to FIGS. 3 and 4 described in the following.

[0031] FIG. 2 shows a schematic illustration of an apical cardiac support system 100 according to one design example. The figure shows a simple illustration of the cardiac support system 100 in the implanted state. The apical cardiac support system 100 comprises an input for introducing a blood flow, which pumps a blood flow from the left ventricle 115 of the heart into the aorta 120 via a drain cannula 205 which is led along the heart 105 outside the heart 105. For this purpose, the pump volume flow 130 is delivered to the drain cannula 205 by a pump of the cardiac support system 100, for example a rotary pump. The drain cannula 205 delivers the pump volume flow 130 to the aorta 120. One design example of the apical cardiac support system 100 shown here also comprises a device for detecting a state of wear or for operating the cardiac support system 100, as shown with reference to FIGS. 3 and 4 described in the following.

[0032] FIG. 3 shows a schematic illustration of a device 300 for detecting a state of wear of a cardiac support system according to one design example. The device 300 comprises a reading device 305 and a determination device 310. The reading device 305 is configured to read in a sensor signal 315 that represents an operating state of the cardiac support system. The determination device 310 is configured to determine a wear signal 325 using the sensor signal 315 and a comparison rule 320. The wear signal 325 represents the state of wear.

[0033] The device 300 shown here can be used in conjunction with a cardiac support system such as one of the two cardiac support systems shown as an example in the preceding FIGS. 1 and 2.

[0034] According to one design example, the determination device 310 is configured to determine at least one wear parameter and to provide the wear signal 325 comprising the wear parameter. Additionally or alternatively, the determination device 310 is configured to determine at least one functional parameter representing a functionality of the cardiac support system and to provide the wear signal 325 comprising the functional parameter.

[0035] According to the design example shown here, the determination device 310 is also configured to provide the wear signal 325 to an interface with an external processing device 335. The sensor signal 315 is optionally also provided to the interface with the external processing device 335. The interface can be wireless or wired.

[0036] According to the design example shown here, the reading device 305 is also configured to read in at least one further sensor signal 330, which represents a further operating state of the cardiac support system. The determination device 310 is configured to determine the wear signal 325 using the sensor signal 315, the at least one further sensor signal 330 and the comparison rule 320. The determination device 310 is also optionally configured to extract a sensor parameter set using the sensor signal 315 and the at least one further sensor signal 330, and to determine the wear signal 325 using the sensor parameter set and the comparison rule 320. According to the design example shown here, the comparison rule is prestored in the determination device. The comparison rule 320 is optionally defined using the sensor signal 315.

[0037] According to the design example shown here, the sensor signal 315 and the further sensor signal 330 are provided by a sensor device 340. The sensor device 340 is optionally configured to sense the operating state and to provide the sensor signal 315 representing the operating state. According to one design example, the sensor device 340 is also configured to sense an electrical quantity, a temperature, a pressure, a volume flow, a movement, an optical or acoustic signal, a force, or a change in position of the cardiac support system in order to provide the sensor signal 315. According to one design example, the sensor signal 315 is configured to represent the operating state in the time domain and additionally or alternatively in the frequency domain.

[0038] In combination with a cardiac support system, the device 300 shown here can be used for monitoring at least one functional group of a cardiac support system so that a maintenance intervention can be carried out before the first symptoms or acute emergencies occur. The sensor device 340 can be a sensor device integrated into the cardiac support system, for example, and configured to determine operating parameters such as currents, voltages, temperatures, vibrations, pressures and pressure changes, sound, optical reflection coefficients, forces and changes in position. According to one design example, sensor parameters are extracted from the sensor data using the determination device 310, for example in the time domain and additionally or alternatively in the frequency domain.

[0039] A fingerprint of the system can, as it were, be generated from the determined sensor parameter set or the sensor parameter set can be regarded as such a fingerprint. Using the determination device 310, the fingerprint can continuously be compared to the definition of a healthy fingerprint in the form of the comparison rule 320. Deviations of the fingerprint from the healthy fingerprint of the comparison rule 320 are an indication of ongoing aging or damage processes of the cardiac support system. The temporal progression of the sensor parameter set is optionally employed using the determination device 310 to assess wear processes of the cardiac support system and possibly predict a time of failure. According to the design example shown here, the determination device 310 is configured to provide the wear signal 325 to the interface with the external processing device 335 to, in the event of a deviation from the normal fingerprint identified by means of the wear signal 325, for example in the form of the wear signal 325 comprising the wear parameter, inform the wearer of the implanted cardiac support system with the device 300, for example, the patient or a physician via the wear signal 325 representing the state of wear.

[0040] Such a monitoring of the condition of the cardiac support system using a variant of the device 300 shown here advantageously makes it possible to achieve a reduction or even a prevention of critical system failures. The early detection of a system degradation provides a time advantage, so that surgery appointments for component replacement, for example, can be planned early. Predictive maintenance interventions increases the patient's quality of life by not exposing the patient to a medical emergency scenario. The device 300 shown here can also be referred to as a condition monitoring system and provides an additional safeguard particularly for subsystems that cannot be configured to be redundant, such as the pump motor. By integrating the device 300 as a condition monitoring system, the patient's confidence in his support system can be increased, which results in a sense of security.

[0041] Using the wear signal 325, the determined state of wear can be transmitted via the interface with the external processing device 335 in the form of a communication interface, such as a radio modem or a wired interface. If the external processing device 335 comprises a display device, for example in the form of a screen of the extracorporeal control device or the portable device, a so-called “wearable”, such as a smartphone coupled via Bluetooth Low Energy as an external processing device 335, the state of wear provided by means of the wear signal 325 can be displayed on the display device, for example in the form of a condition measure of the state of wear.

[0042] By providing the wear signal 325 to the interface with the external processing device 335, the state of wear and/or the underlying sensor values or sensor parameters can additionally or alternatively also be stored for later retrieval (via cable, radio, or an inductively coupled communication interface) in the extracorporeal control device or a control device implanted with the cardiac support system and/or can be transmitted via a wide area communication network (for example, WLAN, LTE, or GPRS) to a central server. The use of a central server has the advantage that the system fingerprint and the parameter trend progression of the sensor data and the state of wear transmitted by means of the wear signal 325 can be compared to a large population of systems, so that it is possible to make robust statements about the system state of the cardiac support system.

[0043] FIG. 4 shows a schematic illustration of a device 400 for operating a cardiac support system according to one design example. The device 400 shown here is configured to operate and additionally or alternatively control the cardiac support system, such as the cardiac support system shown as an example with reference to FIG. 1 or FIG. 2. For this purpose, the device 400 comprises the reading device 305 and the determination device 310, which correspond substantially to the reading device and the determination device shown in FIG. 3. The reading device 305 is correspondingly configured to read in the sensor signal 315 provided by the sensor device 340, and the determination device 310 is configured to determine and provide the wear signal 325 using the sensor signal 315 and the comparison rule 320.

[0044] According to the design example shown here, the device 400 also comprises a control device 405. The control device 405 is configured to provide a control signal 410 for controlling a component 415 of the cardiac support system using the sensor signal 315 or the wear signal 325.

[0045] The component 415 of the cardiac support system is a control unit, for example, or a structural element such as a pump or an impeller or a drive device as shown in the following FIG. 5. If, by means of the sensor signal 315 and additionally or alternatively by the determination of the wear signal 325 using the determination device 310, the device 400 detects a fall or other physical impact on the patient, the device 400 is configured to, using the control device 405, control one of the components 415 of the cardiac support system, such as the pump, by means of the control signal 410 to temporarily slow or stop the pump in order to prevent or reduce damage to the mechanical elements.

[0046] FIG. 5 shows a schematic illustration of an arrangement of sensors of a cardiac support system 100 for a device 300 for detecting a state of wear of a cardiac support system 100 according to one design example. The example sensor integration into the cardiac support system 100 shown here can also be carried out in conjunction with the device 400 for operating the cardiac support system 100. The cardiac support system correspondingly comprises the device 300; 400, for example, which is similar to or the same as a variant of the device as described with reference to the preceding FIGS. 3 and 4. As an example, the cardiac support system 100 shown here is shown as a cardiac support system for the aortic valve position, like the cardiac support system described with reference to FIG. 1.

[0047] The cardiac support system 100 comprises a tip 505, an inlet cage 510 for receiving a blood volume flow, an inlet cannula 515 for delivering the blood volume flow to a micro-axial flow pump, an impeller 520 of the micro-axial flow pump, a magnetically or mechanically coupled electric drive 525, a supply cable 530 and a control unit 535. The control unit 535 comprises the device 300; 400, for example. As an example, the cardiac support system 100 comprises a variety of sensors as a sensor device in an example of a mounting position. According to the design example shown here, the cardiac support system 100 comprises three temperature sensors 542, two of which are disposed in the region of the electric drive 525 and one of which is disposed in the region of the tip 505. As an example, the cardiac support system 100 also comprises three pressure sensors 544, of which one is disposed in the region of the tip 505, one is disposed in the region of the inlet cannula 515 and one is disposed in the region of the electric drive 525. In the region between the tip 505 and the inlet cage 510, the cardiac support system also comprises an ultrasonic flow sensor 546. At an end facing away from the tip 505, the inlet cannula 515 additionally comprises a force, bending or distance sensor 548 and an optical reflection coefficient sensor 550. Adjacent to the impeller 520, the electric drive 525 comprises an impeller position sensor 552 in the form of a magnetic sensor or a Hall sensor, an optical distance sensor such as a laser interferometer, or an inductive and additionally or alternatively capacitive rotor position sensor. In the center of the electric drive 525, the cardiac support system 100 comprises a vibration sensor, a structure-borne sound sensor, a microphone and additionally or alternatively a microcontroller, for example in the form of a sensor hub, as a further impeller position sensor 554. In the region of the point of contact of the control unit 535 with the supply cable 530, the cardiac support system comprises a voltage sensor 556 in the form of a voltage, current, power, electrical resistance and/or back EMF sensor. The control unit 535 further comprises a control device sensor 558 in the form of a microphone, pressure, acceleration and/or rotation rate sensor, or temperature sensor.

[0048] A redundant design of the sensors 542, 544, 546, 548, 550, 552, 554, 556 and 558 shown here is advantageous for self-diagnosis of the sensors 542, 544, 546, 548, 550, 552, 554, 556 and 558 using deviations between the individual sensor values. An integration of all of the sensors 542, 544, 546, 548, 550, 552, 554, 556 and 558 shown here does not make sense in every application or, for reasons of installation space or cost, cannot be implemented in every application. The most relevant sensors can be selected in a targeted manner depending on the specific application, for example on the basis of a failure mode and effects analysis (FMEA analysis) or observed failures in long-term tests or stress tests.

[0049] The following is a list of application examples for the device 300, 400 in conjunction with the cardiac support system 100 and a sensor device such as one or more of the sensors 542, 544, 546, 548, 550, 552, 554, 556 and 558 shown here for detecting the state of wear of the cardiac support system 100 and/or for operating the cardiac support system 100:

[0050] The impeller sensor 554 in the form of the microphone or the structure-borne sound sensor and additionally or alternatively the control device sensor 558 in the form of the microphone and/or an acceleration sensor enables an analysis of the bearing wear by determining the state of wear.

[0051] In the case of magnetically coupled and magnetically mounted impellers 520, aging and deposits and the onset of pump thromboses can result in an imbalance of the impeller 520, which can be detected via the microphone, the acceleration sensor, the rotation rate sensor and the structure-borne sound sensor of the impeller sensor 554 and/or the control device sensor 558.

[0052] A change in friction in the sliding bearings of the cardiac support system 100, for example as a result of wear or the build-up of deposits, can be detected via a change in the power consumption, which can be sensed by a voltage sensor 556 in the form of a current, voltage, or power sensor, in combination with the actual pressure build-up or volume flow build-up, which can be sensed by one of the pressure sensors 544 in the region of the inlet cannula 515 or the electric drive 525 or the ultrasonic flow sensor 546. This error pattern furthermore also leads to a characteristic oscillation, which can be detected by the microphone, the acceleration sensor, the rotation rate sensor and the structure-borne sound sensor of the impeller sensor 554 and/or the control device sensor 558.

[0053] A measurement of the slippage between the magnetically coupled drive 525 and the impeller 520 provides information about the condition of the coupling and the sliding bearings of the impeller 520. The slippage can be sensed via an optical, magnetic or capacitive impeller position sensor 552, for example, or the phase relationship of the electric drive current and the back-induced field energy (back EMF) in currentless turns of the multiphase electric motor 525 can be sensed by means of the voltage sensor 556, for example in the control device 535 or in the electric drive 525. For this purpose, the voltage sensor 556 can be placed in the position shown here or in the region of the electric drive 525 in the position of the temperature sensor 542 or pressure sensor 554 disposed there.

[0054] A load on the bearings and a resulting pressure build-up of the impeller 520 can also be sensed at the bearing of the impeller by means of the force, strain or distance sensors 548.

[0055] Deposits and the onset of pump thromboses can be detected via a pressure drop in the inlet hose in the form of the inlet cannula 515, for example via pressure gradients between the aorta and the inlet cannula 515 or the ventricle, but also via a comparison of the electrical power consumption detectable by means of the voltage sensor 556 with the actual flow detectable by means of the ultrasonic flow sensor 546 and the pressure build-up of the pump detectable by means of the pressure sensors 544.

[0056] Indications of aging processes in the stator of the electric drive 525 are provided by the winding temperature that can be detected by means of the temperature sensor 542 positioned in the region of the electric drive 525, for example, or the winding impedance that can be detected by means of the voltage sensor 556, but also by optically, inductively or capacitively measured dimensions of the motor air gap measured by means of an impeller position sensor 552 in the position of the temperature sensor 542 or pressure sensor 544 disposed in the region of the electric drive 525.

[0057] Deposits on the rotor, as well as an imbalance, can also be determined via optical measurement of the reflection coefficient using the reflection coefficient sensor 550.

[0058] The quality of the supply cable 530 can be monitored via an electrical resistance measurement by means of the voltage sensor 556. In addition to detecting cable breaks (series measurement), the resistance measurement can also be carried out as a complex-valued impedance measurement between adjacent line strands to assess the condition of the insulation jacket and/or dielectric.

[0059] Faults in the power and signal electronics of the control device 535 can be detected by measuring the temperature of individual assemblies and monitoring selected voltage levels.

[0060] Suctioning of a pump inlet to the ventricular wall of the aorta in a cardiac support system 100 in aortic valve position, a so-called “suction”, can also be detected by means of the device 300, 400 shown here. A supporting blood volume flow is no longer possible if the cardiac support system 100 suctions on; the cardiac support system 100 should (automatically) reduce the pump power until said system releases from the aortic wall. Suctioning on can be detected via the pressure gradient of the pressure sensors in the region of the tip 505 and in the region of the inlet cannula 515 and by means of the ultrasonic flow sensor 546. Partial closure of the inlet cage 510 also changes the flow conditions in the inlet cage 510, which can be detected via the Doppler spectrum of the ultrasonic flow sensor 546.

[0061] The sensor data processing by means of the determination device of the device 300, 400 is based on the analysis of the sensor signals in the time domain, for example via relative or absolute threshold values, mean values, standard deviations, minimum and maximum values in time windows or the overall observation period. Additionally or alternatively, the sensor data processing by means of the determination device of the device 300, 400 is based on the analysis of the sensor signals in the frequency domain, for example via a determination of characteristic frequencies, a median frequency of the spectrum, the integrated band energy in defined frequency bands or also the absolute amplitude at the location of known damage frequencies. The mentioned sensor parameters of the operating state can be determined on the basis of predefined threshold values of the comparison rule as condition parameters, i.e.

[0062] as wear parameters, for example. Alternatively, a fingerprint of the system parameters can also be defined as a comparison rule and, for example, a threshold value can be defined on a mathematical distance measure on the fingerprint defined as healthy, for example as a threshold value hyperplane in the multidimensional parameter space.

[0063] The processing of the sensor values can be realized in a pump-integrated microcontroller such as a sensor hub or in the control device 535. The sensor hub can also be used only for preprocessing the sensor data and forwarding extracted sensor parameters, which reduces the required communication bandwidth along the supply cable 530.

[0064] FIG. 6 shows a flow diagram of a method 600 for detecting a state of wear of a cardiac support system and a method 700 for operating a cardiac support system according to one design example.

[0065] The method 600 comprises a read-in step 601 and a determination step 603. In the read-in step 601, a sensor signal representing an operating state of the cardiac support system is read-in. In the determination step 603, a wear signal is determined using the sensor signal and a comparison rule. The wear signal represents the state of wear.

[0066] According to one design example, at least one wear parameter is determined in the determination step 603. In this case, the wear signal includes the at least one wear parameter. In the determination step 603, at least one functional parameter representing a functionality of the cardiac support system is optionally determined as well. The wear signal then comprises the at least one functional parameter.

[0067] The method 600 also optionally comprises a step 605 of providing the sensor signal and/or the wear signal to an interface with an external processing device. The provision step 605 optionally takes place after the determination step 603. If only the sensor signal is provided in the provision step 605, the provision step 605 can also take place subsequent to the read-in step 601.

[0068] According to one design example, the method 600 further comprises a sensing step 607, in which the operating state is sensed and the sensor signal representing the operating state is provided. The sensing step 607 optionally takes place before the read-in step 601. The sensing step 607 is additionally or alternatively carried out before the provision step 605.

[0069] In the read-in step 601, a further sensor signal representing a further operating state of the cardiac support system is optionally read-in. In this case, the wear signal is determined in the determination step 603 using the sensor signal, the further sensor signal and the comparison rule. A sensor parameter set is optionally also extracted in the determination step 603 using the sensor signal and the further sensor signal. The wear signal is then determined using the sensor parameter set and the comparison rule.

[0070] According to one design example, the method 600 further comprises a step 609 of defining the comparison rule using the sensor signal. The defining step 609 is optionally carried out after the read-in step 601 before the determination step 603.

[0071] The method 700 for operating a cardiac support system comprises at least step 601 and step 603 of the method 600 and optionally one or more of steps 605, 607 and 609 as described above. The method 700 further comprises a step 701 of providing a control signal for controlling a component of the cardiac support system. The control signal is provided using the sensor signal or the wear signal.

[0072] If a design example includes an “and/or” conjunction between a first feature and a second feature, this should be read to mean that the design example according to one embodiment comprises both the first feature and the second feature and, according to another embodiment, comprises either only the first feature or only the second feature.