阅读说明：本技术 使用光纤传感器作为基于导管的医疗设备中的诊断工具 (Using fiber optic sensors as diagnostic tools in catheter-based medical devices ) 是由 R·S·甘地 T·张 于 2019-09-20 设计创作，主要内容包括：一种血泵系统,包括：光学传感器,其配置为在血泵的泵送操作期间检测光学信号；以及光纤,其配置为将光学信号从光纤传感器传输到通信地联接至光纤传感器的评估设备。评估设备被配置为接收传输的光学信号和指示电动机电流的信号作为输入,并基于电动机电流和光学信号确定与血泵相关的机械故障事件。(A blood pump system comprising: an optical sensor configured to detect an optical signal during a pumping operation of the blood pump; and an optical fiber configured to transmit the optical signal from the optical fiber sensor to an evaluation device communicatively coupled to the optical fiber sensor. The evaluation device is configured to receive as inputs the transmitted optical signal and a signal indicative of the motor current and to determine a mechanical fault event associated with the blood pump based on the motor current and the optical signal.)

1. A blood pump system, the system comprising:

a catheter having a proximal end and a distal end;

a blood pump having a motor coupled to the catheter, wherein the motor has a motor current;

a fiber optic sensor configured to detect optical signals during a pumping operation of the blood pump;

an optical fiber configured to transmit the optical signal from the optical fiber sensor to an evaluation device communicatively coupled with the optical fiber sensor,

wherein the evaluation device is configured to:

receiving as inputs the transmitted optical signal and a signal indicative of the motor current,

calculating a signal-to-noise ratio (SNR) of the optical signal,

a predetermined threshold value of the received SNR is determined,

comparing the calculated SNR with the predetermined threshold, and

determining a mechanical fault event associated with the blood pump; and

wherein the evaluation device determines that a mechanical fault event associated with the blood pump has occurred when, within a period of time:

(1) the motor current is greater than zero, an

(2) The increase in the calculated SNR over the time period exceeds the predetermined threshold.

2. The blood pump system of claim 1, wherein the evaluation device is configured to generate and output an indicator related to the mechanical fault event in response to determining the mechanical fault event.

3. The blood pump system of any of claims 1-2, wherein the evaluation device is configured to determine the threshold based on a baseline SNR.

4. The blood pump system of claim 3, wherein the determined threshold is twice the magnitude of the baseline SNR.

5. The blood pump system of any of the preceding claims, wherein the evaluation device is configured to determine a pressure signal based on the transmitted optical signal.

6. The blood pump system of claim 5, wherein the evaluation device is configured to determine the mechanical fault event based on the calculated SNR, the motor current, and the determined pressure signal.

7. The blood pump system of any preceding claim, wherein the fiber optic sensor is coupled to the pump housing.

8. The blood pump system of any preceding claim, wherein the fibre-optic sensor is located at a distal end of the catheter.

9. The blood pump system of any preceding claim, wherein the period of time is between about 1 to about 5 minutes.

10. The blood pump system of any of claims 1-8, wherein the period of time is between about 5 to about 10 minutes.

11. The blood pump system of any of the preceding claims, further comprising:

a second fiber sensor configured to detect a second optical signal; and

a second optical fiber configured to transmit the second optical signal from the second optical fiber sensor to an evaluation device communicatively coupled with the second optical fiber sensor.

12. The blood pump system of any preceding claim, wherein based on the calculated SNR, the evaluation device is configured to detect a shock in any of a pump, a motor, and a cannula of a pump.

13. A method of determining a mechanical fault event of a blood pump, the method comprising:

determining a motor current of a motor coupled to a catheter and driving the blood pump;

detecting an optical signal at the blood pump;

transmitting the optical signal from the fiber optic sensor to an evaluation device using an optical fiber;

calculating, at the evaluation device, a signal-to-noise ratio (SNR) based on the transmitted optical signal; and

determining a mechanical fault event associated with the blood pump based on the calculated SNR and the determined motor current, wherein the evaluation device determines that a mechanical fault event associated with the blood pump has occurred when:

(1) the motor current is greater than zero, an

(2) The increase in the calculated SNR over the time period exceeds the predetermined threshold.

14. The method of claim 13, wherein in response to determining the mechanical fault event, generating and outputting an indicator related to the mechanical fault event.

15. The method of claim 13, further comprising determining a threshold based on a baseline SNR.

16. The method of claim 15, wherein the determined threshold is twice the magnitude of the baseline SNR.

17. The method of any of claims 13-16, further comprising determining a pressure signal based on the transmitted optical signal.

18. The method of claim 17, further comprising determining the mechanical fault event based on the calculated SNR, the determined motor current, and the determined pressure signal.

19. The method of any of claims 13-18, wherein the fiber optic sensor is coupled to the motor.

20. The method of any of claims 13-19, wherein the fiber optic sensor is located at a distal end of the catheter.

21. The method of any one of claims 13-20, wherein the period of time is between about 1 to about 5 minutes.

22. The method of any one of claims 13-21, wherein the period of time is between about 5 to about 10 minutes.

23. A method of operating a catheter-based blood pump system driven by a motor, the blood pump system including an inlet cannula and a pump having a rotor in a shroud, the method comprising the steps of:

actuating a rotor of the pump by sending a current from the motor to the rotor,

detecting current flow to and from the motor,

detecting vibration of parts of said pump, an

Adjusting a current to the motor based on the detected vibration.

24. The method of claim 22, wherein the detected vibration is indicative of a bearing failure in the pump.

25. The method of any of claims 13-24, wherein detecting a shock or mechanical fault comprises detecting an optical signal from an optical sensor positioned on or near at least one of the shroud, the sleeve, and the motor.

26. The method of any of claims 13-25, further comprising identifying a fault in the rotor by detecting a change in vibration of the pump or casing during a period of time when current to the motor is positive.

Background

Catheter-based medical devices may be monitored to ensure that the device is functioning properly. For example, early and reliable detection of bearing failure in a blood pump may help prevent any sudden stop of the pump and associated adverse effects on the patient. Some blood pumps use motor current as a sense signal to monitor pump performance. But motor current does not always capture early signs of bearing failure and is affected by other factors.

The blood pump may be integrated with a fiber optic pressure sensor to monitor the position of the pump in the patient vasculature. In addition to monitoring pressure signals, fiber optic sensors can also be used to monitor stress/strain, temperature, and vibration. For example, as described in U.S. patent No. 9,669,144, a fiber optic sensor may be used to monitor kinks in a catheter. Fiber optic sensors have not been employed to detect the continuous operating characteristics of catheter-based medical devices.

Disclosure of Invention

The systems, methods, and devices described herein provide for the use of optical fibers as diagnostic tools to assess the performance and status of catheter-based medical devices, and ultimately detect potential failures. Improvements in the system (adaptation) may include an optical sensor and an optical fiber connecting the sensor to a monitor or other signal processing device configured to receive input signals from the sensor and determine characteristics of the medical device. In some implementations, the tool is used to detect mechanical failure of the blood pump. Embodiments of a blood pump system are disclosed that include an optical sensor configured to detect an optical signal during a pumping operation of the blood pump, and an optical fiber configured to transmit the optical signal from the optical fiber sensor to an evaluation device communicatively coupled to the optical fiber sensor. The sensor is positioned near the pump to detect disturbances in the blood caused by the pumping action of the pump, which disturbances may cause changes or deformations in the optical sensor head. The sensor head deforms based on the pressure of the blood pressing on the sensor head. When the sensor head is deformed, the light jumps into the sensor fiber and is picked up by the evaluation device. The reflected light is compared to a reference or baseline signal and a pressure signal is extracted from the comparison. Using the reflected light, the sensor may also detect disturbances in the blood stream caused by vibrations in a pump housing, rotor, motor or cannula included in the pump system. In some refinements, the sensor is attached to or placed adjacent to the pump housing, or placed near the pump motor (in the case of an implantable motor). The evaluation device may be configured to receive as inputs the transmitted optical signal and a signal indicative of the pump motor current and determine a mechanical fault event associated with the pump based on the motor current and the optical signal.

The tool may be used in conjunction with one or more other parameters (e.g., motor current readings and other sensor readings, such as placement signals and flow rates) to enhance detection. In a first implementation, the tool is implemented in a blood pump system that includes a catheter having a proximal end and a distal end, a blood pump having a motor coupled with the catheter, an optical sensor configured to detect an optical signal during a pumping operation of the blood pump, and an optical fiber extending through the catheter and configured to transmit the optical signal from the optical sensor to an evaluation device communicatively coupled to the optical sensor. An optical sensor is positioned at or near the pump in order to detect disturbances in the blood caused by the pumping action of the pump. The evaluation device is configured to receive the input signal and determine whether a mechanical malfunction event associated with the blood pump has occurred. In some implementations, the determination is made based on the input optical signal and a motor current of the blood pump motor. If the pump stops pumping or encounters resistance during operation, the optical signal (and the noise associated therewith) will change due to changes in the vibration of the motor, pump or pump parts or casing, and such changes can be detected by the evaluation device. The evaluation device may be configured to receive as inputs the transmitted optical signal and a signal indicative of the motor current, calculate a signal-to-noise ratio (SNR) of the optical signal, receive a predetermined threshold value of the SNR, compare the calculated SNR to the predetermined threshold value, and determine a mechanical failure event associated with the blood pump, pump part, cannula, or pump motor.

A change in SNR may indicate a problem with the pump. SNR is related to the vibrations of the blood pump or the system parts (e.g., cannula or motor) (as used herein, pump vibrations generally refer to the mechanical vibrations of the implanted device (including the pump, its parts, or cannula or motor that occur when the device is operated in vivo)). When the motor stops, the pump will also stop and accordingly the motor current will be zero and the vibrations will be minimal. In this state, the SNR is relatively large because the noise level of the optical signal is low due to the small mechanical vibration of the pump. Under normal conditions, when the motor is running, the motor current is greater than zero and the pump vibrations increase. During this state, the SNR is relatively low because the noise level of the optical signal is large. Mechanical failure events may occur, resulting in the pump jamming, slowing down or stopping altogether. In this state, the motor current is greater than zero (indicating that the motor is driving current) for a period of time but the SNR increases, e.g., the calculated SNR increases for a period of time until a predetermined threshold is exceeded, then a fault may be detected. A motor current greater than zero indicates that the motor is operating as if the pump were operating properly, while an increase in SNR indicates that the pump is experiencing more vibration, which may indicate that the pump is malfunctioning even though it continues to pump (e.g., the bearings may wear).

The evaluation device may be configured to generate and output an indicator associated with the mechanical fault event in response to determining the mechanical fault event.

In some implementations, the evaluation device is configured to determine the threshold based on the baseline SNR. The threshold may be the SNR (or average) during normal pump steady state operation. In some implementations, the determined threshold is twice the baseline SNR, or at least 3x or 10x or more.

In certain implementations, the evaluation device is configured to determine a pressure signal based on the transmitted optical signal and use the signal to evaluate pump performance. For example, the evaluation device may be configured to determine a mechanical fault event based on the calculated SNR, the motor current, and the determined pressure signal.

The optical fiber is positioned to receive a detectable signal that can be readily used to evaluate the performance of the device. In some implementations, the fiber optic sensor is attached to the pump housing, or to a catheter or cannula near the motor, but positioned such that it is in contact with blood flowing from the pump (or through the motor). According to some implementations, the fiber optic sensor is located at the distal end of the catheter. In some implementations, the diagnostic tool includes a second fiber optic sensor that detects a second optical signal and a second optical fiber that transmits the second optical signal to the evaluation device. The second optical signal may be placed, for example, near the distal end of the pump (e.g., near the pump inlet opening) to detect a change in SNR of the pumping cadence associated with the distal end of the pump. Such signals may also be used to determine mechanical fault events.

The user can adjust the period of time during which pump performance (and in particular SNR and motor current) is monitored for short or long term monitoring. In some implementations, the time period is set to about 1 to about 5 minutes. According to certain implementations, the period of time is between about 5 and about 10 minutes, or up to 6 hours, up to 24 hours, or up to one week or more.

The present disclosure also contemplates various methods, for example, which provide a method of determining a mechanical failure event of a blood pump during operation of the pump. The method includes determining a motor current of a motor driving the blood pump. The method further includes detecting the optical signal at the blood pump during operation of the pump and transmitting the optical signal from the optical sensor (e.g., placed near the pump housing or pump rotor) to the evaluation device using the optical fiber. Further, the method includes calculating, at the evaluation device, a signal-to-noise ratio (SNR) based on the transmitted optical signal. The method also includes determining a mechanical fault event associated with the blood pump motor based on the calculated SNR and the determined motor current. A change in SNR may indicate a problem with the pump (e.g., mechanical stress that may lead to device failure). In some configurations, a mechanical fault event is triggered when the motor current is greater than zero for a period of time and the calculated SNR increases beyond a predetermined threshold during the period of time.

In some implementations, the method further includes, in response to determining the mechanical fault event, generating and outputting a signal indicative of the mechanical fault event. For example, a signal indicative of a mechanical fault event may be transmitted to the processing system and displayed as an audible alarm, a visual alarm, or both.

In certain implementations, the method further includes determining the threshold based on a baseline SNR occurring, for example, during normal operation of the pump. According to some implementations, the determined threshold is twice the size of the baseline SNR.

In some implementations, the method further includes determining a pressure signal based on the transmitted optical signal. In certain implementations, the method further includes determining a mechanical fault event based on the calculated SNR, the determined motor current, and the determined pressure signal.

In certain implementations, the fiber optic sensor is coupled to the motor. According to some implementations, the fiber optic sensor is located at the distal end of the catheter.

In some implementations, the period of time is between about 1 to about 5 minutes. According to some implementations, the time period is between about 5 to about 10 minutes.

In accordance with a further implementation of the present disclosure, a method is provided for operating a catheter-based blood pump system driven by a motor, the blood pump system including an inlet cannula and a pump having a rotor in a shroud. The method includes actuating a rotor of the pump by sending a current from the motor to the rotor. The method also includes sensing current flowing to and from the motor. The method also includes detecting vibration of the pump component, or the sleeve, motor, or other system component. The method may further include adjusting the current to the motor based on the detected vibration. In some implementations, the detected vibration is indicative of a bearing failure in the pump rotor or the motor. In other implementations, detecting the vibration includes detecting an optical signal from an optical sensor positioned on or near at least one of the shroud, the sleeve, and the motor. In certain implementations, the method further includes identifying a fault in the pump rotor by detecting a change in vibration of a system component (e.g., pump or casing) during a period of time when the current to the motor is positive.

The systems and methods may be applied to blood pump systems having various pump configurations. For example, it may be applied to a pump with an on-board motor having a motor coupled to the pump rotor and the conduit (e.g., an Impella system), or to an external motor and a pump driving a cable (e.g., a Hemopump-type pump for converting torque provided by an external motor).

Drawings

The foregoing and other objects and advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

FIG. 1 shows an isometric view of an illustrative blood pump placed through the aorta, extending through the aortic valve into the left ventricle, and having one or more integrated fiber optic sensors;

FIG. 2 shows a cross-sectional view of the fiber optic sensor of FIG. 1 with an optical fiber;

FIG. 3 shows an illustrative graph of a continuous recording of motor current and calculated signal-to-noise ratio based on signals from the fiber optic sensors of FIGS. 1 and 2 for the blood pump of FIG. 1;

FIG. 4 shows an illustrative graph of a continuous recording of calculated SNR based on signals from the fiber optic sensor of FIG. 2;

5A-C show illustrative graphs of successive recordings of placement signals and motor currents of the blood pump of FIG. 1 and calculated SNR based on signals from the fiber optic sensors of FIGS. 1 and 2;

FIG. 6 shows an illustrative method for determining a mechanical fault event associated with the blood pump of FIG. 1;

FIG. 7 illustrates a method of generating and outputting indicators associated with the determined mechanical fault event of FIG. 6 and the blood pump of FIG. 1;

FIG. 8 shows 7 illustrative graphs representing data collected from a blood pump system; and

fig. 9 shows 7 illustrative graphs representing data collected from the blood pump system over a period of time following that shown in fig. 8.

Detailed Description

Certain illustrative embodiments will be described in order to provide a general understanding of the systems, methods, and devices described herein. The systems, methods, and devices described herein provide for the use of fiber optic sensors as diagnostic tools to assess the performance and status of catheter-based medical devices. The evaluation device is used to calculate the signal-to-noise ratio (SNR) of the optical signal from the fiber optic sensor. The SNR can be used to determine the magnitude of mechanical vibrations of a medical device, such as an intracardiac blood pump. At higher vibrations, the SNR is much lower than at lower vibrations. In addition, the rise in the SNR signal coincides with a mechanical failure event of the medical device while the medical device is operating. For example, transient spikes on the SNR signal of a blood pump may coincide with pump bearing failures. In contrast, under static conditions without vibration, no transient displacement was observed.

The SNR using fiber optic sensors (alone or in combination with other operating parameters) may facilitate earlier and more reliable detection of mechanical failure events and instabilities. Early and reliable detection of mechanical failure in the blood pump can help prevent sudden and harmful stopping of the pump and associated adverse effects on the patient. The SNR of the fiber optic sensor may also help determine the location of the device within the body. Proper placement of the device in the body is important for optimal performance. Another advantage of using the SNR of the fiber optic sensor is that it can be used to detect vibrations and evaluate the performance, stability and temperature of the device.

Fig. 1 shows an intracardiac blood pump with a catheter 10, which is introduced retrograde into the descending aorta 11. Descending aorta 11 is a portion of aorta 12 that first rises from the heart and then descends and has an aortic arch 14. At the beginning of the aorta 12, an aortic valve 15 connects the left ventricle 16 to the aorta 12, and an intracardiac blood pump extends through the aortic valve 15. In addition to the catheter 10, the blood pump further comprises a rotary pumping device 50 secured at the distal end of the catheter hose 20. The pumping device 50 has a motor part 51 coupled to the guide tube and the guide tube 10 arranged distally from the motor part 51, and a flow sleeve 53 protruding from the pump part 52 in the distal direction. The pump portion has a rotor within a shroud. The cannula has a distal inlet 54 and a proximal outlet at the proximal end of the rotor. The motor speed of the rotary pumping device 50 is dependent on the motor current driving the rotary pumping device 50. At the distal end of the suction opening 54 there is provided a soft-flexible tip 55, for example configured as a "pigtail".

Various fluids, electrical wires and other lines extend through the catheter hose 20 to operate the pumping device 50. Therein, fig. 1 shows a configuration with two optical fibers 28 and 29 attached at their proximal ends to an evaluation device 100. These optical fibers 28 and 29 are part of an optical pressure sensor, respectively, whose sensor heads 60 and 30 are located on the one hand outside the housing of the pump part 52 and on the other hand outside the suction opening 54. The sensor head 60 is in contact with blood flowing into the aorta and is therefore able to detect optical signals within the blood flowing in the aorta (to measure aortic pressure and detect pump vibrations). The sensor head 30 is positioned (in use) near the distal end of the pump in the left ventricle so that it contacts blood in the left ventricle to measure left ventricle pressure (and also detect pump or cannula vibrations). For example, optical signal measurements are performed by transmitting pulses (or continuous streams) of light into the blood stream and receiving return pulses forming an optical sensor signal, which can be returned to the evaluation device for processing. The return pulse is a reflection of the original pulse that couples back into the sensor head due to deformation of the glass films of the sensor heads 30 and 60, as described below. The optical signals from the sensor heads are transmitted to the evaluation device 100, which the evaluation device 100 converts into electrical signals and transmits and displays them on the display screen 101. Although two sensors are shown, the system may be configured to use only one sensor. As discussed further below, the sensor head 60 is in the vicinity of the pump housing and motor portion 51 where vibration will be greatest, and thus the sensor head 60 may be more suitable than the sensor 30 for detecting mechanical failure events. The sensor 30 may also be used to detect rhythmic changes in casing movement during pumping, which may also indicate pump failure. The motor current of the rotary pumping device 50 is also transmitted to the evaluation device 100 via electrical leads in the catheter and can be displayed on a display screen 101.

The sensors may provide a variety of beneficial information. The system can measure aortic pressure via a sensor head 60 (and optionally another sensor, such as sensor 30) positioned within the patient. If other sensors are used, other pressures may also be detected, such as the ventricular pressure through the sensor head 30. The pressure measurement may also provide a contractility measurement to track the recovery of the heart. Contractility represents the intrinsic ability of the myocardium to contract. The pressure signal may also be evaluated to identify a differential pressure that may be used to calculate blood flow through the cannula of the pumping device 50. Ventricular pressure and the amount of blood flow during the heartbeat can be used to determine contractility. The distal sensor head 30 may also extend into the soft flexible tip 55, e.g., positioned such that the head protrudes from the tip, to detect ventricular pressure. By detecting ventricular pressure with the sensor head 30, the clinician can detect when the pump is traversing the aortic valve. In addition, the sensor is sensitive enough to detect slight bending of the tip 55, which can guide the clinician more effectively to push the pump through the valve. As shown in fig. 1, the sensor may also detect excessive pressure on the heart wall due to bending or kinking when the pump is positioned near the heart wall, for example, due to the suction of the inlet into the mitral valve and chordae tendineae inside the ventricle. Detection of this condition allows the user to rotate or withdraw the pump.

Fig. 2 further illustrates an electro-optical pressure measurement. Fig. 2 shows a pressure measuring catheter 26 with a lumen 27 in which an optical fiber 29 (and optionally 28) can move freely. The catheter 26 may preferably be made of nitinol or another shape memory alloy or polymer hose. As shown in fig. 1, the conduit 26 exits the conduit hose 20 at an exit point 57 and is directed along (e.g., externally to) the flexible flow sleeve 53. At the distal end 34 of the optical fiber 29 (or 28), the pressure measurement catheter has a sensor head (e.g., 30 or 60) with a head housing 31, the head housing 31 containing a thin glass membrane 32 abutting a lumen 33. Light strikes the glass film 32 and enters and exits the optical fiber 28 (or 29) in a low loss manner (i.e., with little attenuation loss over the entire length of the fiber). The glass film 32 is pressure-sensitive and deforms according to the magnitude of the pressure acting on the sensor head 30 (or 60). Deformation of the glass film 32 causes light to be reflected and coupled back into the optical fiber 28 (or 29). At the proximal end of the optical fiber 28 (or 29), i.e. in the evaluation device 100, a digital camera, e.g. a CCD camera or CMOS, receives the incident light and generates a pressure dependent electrical signal. For example, a camera may receive incident light and generate an optical image or pattern, which is then transmitted to a signal processor in an evaluation device configured to receive the image or pattern as input and use it to calculate a pressure signal. In some embodiments, the signal processor is configured to use the calculated pressure signal to control the supply of electrical power to the motor-operated pumping device 50. For example, if the calculated pressure signal is low, the signal processor increases the power supply to the motor-operated pumping device 50. If the calculated pressure signal is high, the signal processor reduces the power supply to the electrically operated pumping device 50.

As described above, the distal sensor head 30 extends into the soft flexible tip 55 for sensing ventricular pressure at the tip 55 of the pump. As shown, a head 60 is positioned proximal to the pump and held in the aorta to detect aortic pressure. Its signal is detected and transmitted to the evaluation device 100. The signals from heads 30 and 60 may be compared at evaluation device 100 and used to calculate a differential pressure signal/measurement, which is used for pump placement and monitoring. Differential signals or measurements may also be used in conjunction with motor current and other parameters to monitor pump placement and performance, as discussed herein. Furthermore, this enables a very sensitive detection of the bending of the tip 55, which enables a simpler valve crossing. When the pump is located near the wall, as shown in fig. 1, excessive pressure on the heart wall due to bending or kinking may be detected. The latter may also cause the portal to be sucked up on the cardiac structure. The user can correct this detection by rotating or withdrawing the pump.

The distal sensor head 60 and the optical fiber 28B may be used to detect a mechanical fault event at the motor portion 51 of the rotary pumping device 50. The optical signal transmitted from the distal sensor head 60 to the evaluation device 100 using the optical fiber 28B may be used by the evaluation device 100 to calculate the SNR of the optical signal. The SNR is related to the mechanical vibration of the rotary pumping device 50. When the rotary pumping device 50 is stopped, the mechanical vibrations of the rotary pumping device 50 are minimal. In this state, since the noise level of the optical signal is low, the SNR is relatively large. When the rotary pumping device 50 is operated, the mechanical vibration of the rotary pumping device 50 increases. During normal operation, the SNR is relatively low because the noise level of the optical signal is large and the motor current is greater than zero (because the motor is driving current to the pump). The SNR when the rotary pumping device 50 is operating under this normal condition may be considered the baseline SNR and may be used to determine a threshold SNR for detecting a change in SNR that may signal a mechanical failure event. During a mechanical failure event, when the speed of the rotary pumping device 50 is reduced, for example due to a bearing failure or a rotor portion seizing, the SNR may increase for a short time, but the motor current is positive, indicating that the motor is still operating.

An increase in SNR above a baseline (or other threshold) can be detected and evaluated to assess pump performance. In some applications, the evaluation device 100 determines whether a mechanical failure event has occurred by determining whether an increase in SNR over a period of time exceeds a threshold value over a period of time (or some point in time) during which the pump is operating (e.g., as indicated by motor current being positive). Prior to the mechanical failure event, the evaluation device 100 will be configured with a threshold based on the baseline SNR. For example, the threshold may be set as a factor (e.g., one-quarter, one-third, one-half, or two times) of the magnitude of the baseline SNR. Other thresholds may be used by the evaluation device 100 to determine mechanical failure events. Alternatively, the evaluation device 100 may receive an input from the user indicating a threshold value for evaluating the SNR variation. The time period for evaluating the SNR may be any time period required. For example, the input period of time may be one minute, between about one and about five minutes, between about five and about ten minutes, or between about ten minutes and about twenty minutes. Other time periods may be used by the evaluation device 100 to determine mechanical failure events. If the evaluation device 100 determines that a mechanical fault event has occurred, for example, if the SNR exceeds a threshold value during an evaluation period in which the motor current remains positive, the evaluation device 100 may generate and output an indicator related to the mechanical fault event. The indicator may be displayed on the display screen 101.

Fig. 3 shows an illustrative graph 300 of a continuous recording of motor current and calculated SNR based on signals from the fiber optic sensors of fig. 1 and 2 for the rotary pumping device 50 of fig. 1 over a period of several days. Graph 300 includes motor current 302 and SNR 304. The motor current 302 of the rotary pumping device 50 is transmitted to the evaluation device 100 over a period of several days and is greater than zero when the rotary pumping device 50 is running and zero when the motor is stopped. The baseline SNR would be the SNR when the rotary pumping device 50 is operating because the SNR is relatively low. During the bearing failure event 306, the SNR304 increases from the baseline SNR over a short period of time (e.g., a few minutes in the example of fig. 3). For example, as shown in fig. 3, SNR304 increases from a baseline SNR of approximately 3500 to SNR304 of 5500. Because the speed of the rotating pumping device 50 has decreased due to bearing failure, the SNR increases over this short period of time, and thus the pump vibrations slow down. In this example, the SNR increases by about 2000 over a short period of time. The evaluation device 100 determines a threshold SNR for detecting the bearing failure event 306. For example, because the baseline SNR is the SNR during normal operation of the pump, the evaluation device 100 may determine the threshold based on the baseline SNR. Large deviations from the SNR during pump operation indicate a bearing failure event. It may also indicate other failures of the pump. The evaluation device 100 may determine that the threshold is a fixed and/or predetermined amount of the baseline SNR. For example, as shown in fig. 3, the evaluation device 100 may determine that the threshold is half of the baseline SNR (3500) or 1750. The evaluation device 100 may determine that a bearing fault event 306 occurred because the motor current is greater than zero (the rotary pumping device 50 is running) and the increase in SNR (2000) is greater than the threshold (1750) over a short period of time. At least one advantage of using the SNR304 of the fiber optic sensor in conjunction with the motor current 302 is that it allows for earlier and more reliable detection of a pump failure event 306 (e.g., a bearing failure, which is otherwise difficult to detect). Unlike previous generations of blood pumps, the systems and methods of the present disclosure contemplate using an optical sensor to evaluate pump performance by detecting a signal from a fiber optic sensor, such as SNR 304. The sensor may also be used to monitor placement of the pump in the vasculature. .

Fig. 4 shows an illustrative graph 400 of a continuous recording of SNR calculated based on signals from the fiber optic sensor of fig. 2 over a period of one or more months. Graph 400 includes a first SNR 402 and a second SNR 404. The first SNR 402 and the second SNR 404 are obtained from the evaluation device 100 at different points in time and compared in the graph 400, respectively. During normal operation for several days, the first SNR 402 and the second SNR 404 do not increase for a short period of time. To simulate a bearing fault event 406, power to the blood pump is shut down. During the bearing failure event 406, the first SNR 402 and the second SNR 404 increase over a short period of time due to a power loss. The loss of power reduces the speed of the rotary pumping device 50, resulting in reduced vibration. The vibration reduction simulates a bearing failure event 406. As described with respect to fig. 3, the evaluation device 100 may determine that a bearing failure event 406 has occurred based on the first SNR 402 and the second SNR 404. Fig. 4 shows the reliability of using the SNR signal as an indicator of bearing failure, since there is little false positive.

Alternatively, the evaluation device 100 may use the placement signal, the motor current, and the SNR to determine whether a mechanical fault event has occurred. The placement signal is calculated by the evaluation device 100 from the transmitted optical signal of the sensor head 60 and indicates the pressure. The placement signal may be used in conjunction with the processes described above with respect to fig. 3 and 4 to determine a mechanical failure event. For example, fig. 5A-C show three illustrative graphs of the placement signal and motor current of the rotary pumping device 50 of fig. 1 and a continuous recording of the calculated SNR based on the signals from the fiber optic sensors of fig. 1 and 2. As shown in each of the three graphs of fig. 5A-C, when the placement signal is stable, the evaluation device may determine that the SNR decreases as the motor speed increases because the mechanical vibrations of the rotary pumping device 50 increase as the motor speed increases. If the placement signal is stable, the motor speed/current is stable and the SNR increases within a short period of time, the evaluation device 100 will identify a mechanical fault event. For example, the SNR increase may be instantaneous. In some examples, the SNR increase may occur over a time period of between about 100 milliseconds and about 1 second or between about 1 second and about 10 seconds. In other examples, the increase in SNR may occur over a period of about one minute to about five minutes or about five minutes to about ten minutes. Using SNR in combination with the placement signal and motor current is advantageous because the placement signal provides more information about the location of the pump within the patient.

Fig. 6 illustrates a method 600 of determining a mechanical fault event associated with the blood pump 50 of fig. 1. In step 602, the evaluation device 100 determines the motor current of the motor driving the blood pump. For example, as mentioned above with respect to fig. 1 and 2, the motor current of the rotary pumping device 50 is transmitted to the evaluation device 100 and may be displayed on the display screen 101.

In step 604, the evaluation device 100 determines whether the motor current is greater than zero. For example, if the rotary pumping device 50 is stopped, the motor current is zero, whereas if the rotary pumping device 50 is running, the motor current is greater than zero. If the motor current is zero, method 600 ends at step 606. However, if the motor current is greater than zero, the method 600 proceeds to step 608.

In step 608, the evaluation device 100 detects an optical signal at the blood pump. For example, as mentioned above with respect to fig. 1 and 2, the glass membrane 32 is pressure sensitive and deforms in response to the amount of pressure acting on the sensor head 60 (or 30). For example, deformation of the glass film 32 causes light to be reflected and coupled back into the optical fiber 28 (or 29).

At step 610, the optical fiber 28 transmits the optical signal from the fiber sensor to an evaluation device. For example, as mentioned above with respect to fig. 1 and 2, the optical signals transmitted by the sensor heads 30 and 60 can be converted into electrical signals in the evaluation device 100 and displayed, for example, on the display screen 101.

In step 612, the evaluation device 100 calculates the SNR based on the transmitted optical signal. For example, the optical signal transmitted from distal sensor head 60 to evaluation device 100 using optical fiber 28 may be used by evaluation device 100 to calculate the SNR of the optical signal. SNR is linked to the mechanical vibration of the rotary pumping device 50. When the rotary pumping device 50 is stopped, the motor current is zero and the mechanical vibrations of the rotary pumping device 50 are minimal. In this state, since the noise level of the optical signal is low, the SNR is relatively large. When the rotary pumping device 50 is operated, the motor current is greater than zero and the mechanical vibration of the rotary pumping device 50 increases. In this state, since the noise level of the optical signal is large, the SNR is relatively low.

At step 614, the evaluation device 100 determines a mechanical failure event associated with the blood pump motor based on the calculated SNR. As mentioned above with respect to fig. 1 and 2, when the rotary pumping device 50 is stopped, the mechanical vibrations of the rotary pumping device 50 are minimal. In this state, since the noise level of the optical signal is low, the SNR is relatively large. When the rotary pumping device 50 is operated, the motor current is greater than zero and the mechanical vibration of the rotary pumping device 50 increases. The rapid rise in SNR from the baseline (e.g., when the pump is operating normally) signals that the pump has a mechanical problem. For example, during a fault condition, the SNR is relatively low because the noise level of the optical signal is large, but the motor current is greater than zero, indicating that the motor is driving the pump with current, but the pump is not pumping (or slowing). The evaluation device 100 determines a threshold SNR for detecting a mechanical failure event. In an aspect, the evaluation device may receive a threshold SNR from a user input. Alternatively, the SNR when the rotary pumping device 50 is operating may be considered the baseline SNR and may be used to determine a threshold SNR for detecting a mechanical failure event. During a mechanical failure event, the SNR increases in a short time as the speed of the rotary pumping device 50 decreases, for example due to a bearing failure. Step 614 is described in more detail below with respect to method 700 of fig. 7.

Fig. 7 illustrates a method 700 of generating and outputting an indicator associated with the method 600 and a determined mechanical failure event of the blood pump of fig. 1. In step 702, the evaluation device 100 receives as input the transmitted optical signal and a signal indicative of the motor current. For example, as mentioned above with respect to fig. 1 and 2, the motor current of the rotary pumping device 50 is transmitted to the evaluation device 100 and may be displayed on the display screen 101, and the optical signal transmitted by one or both of the sensor heads 30 and 60 may be converted in the evaluation device 100 into an electrical signal and displayed, for example, on the display screen 101.

In step 704, the evaluation device 100 determines whether the motor current is greater than zero. For example, if the rotary pumping device 50 is stopped, the motor current is zero, whereas if the rotary pumping device 50 is running, the motor current is greater than zero. If the motor current is zero, the method 700 ends at step 706. However, if the motor current is greater than zero, the method 700 proceeds to step 708. When the rotary pumping device 50 stops (or slows down), the mechanical vibrations of the rotary pumping device 50 are slow and reach a minimum when the pump stops. During the pump-off state, the SNR is relatively large because the noise level of the optical signal is low. When the rotary pumping device 50 is operated, the motor current is greater than zero and the mechanical vibration of the rotary pumping device 50 increases. In this state, during normal pump operation, the SNR is relatively low because the noise level of the optical signal is large.

But at pump failure or failure, the SNR changes and the following steps help in the identification. In step 708, the evaluation device 100 calculates the SNR based on the transmitted optical signal. For example, the optical signal transmitted from the proximal sensor head 60 to the evaluation device 100 using the optical fiber 28 may be used by the evaluation device 100 to calculate the SNR of the optical signal. The SNR is related to the mechanical vibration of the rotary pumping device 50.

In step 710, the evaluating device 100 receives a predetermined threshold value of SNR. For example, the SNR when the rotary pumping device 50 is operating may be considered the baseline SNR and may be used to determine a threshold SNR for detecting a mechanical failure event. The evaluation device 100 may determine a threshold based on the baseline SNR prior to the mechanical failure event. For example, the threshold may be a factor (e.g., one-fourth, one-half, or two times) of the magnitude of the baseline SNR.

In steps 712 and 714, the evaluation device 100 compares the calculated SNR over a time period to a predetermined threshold and determines whether the increase in the calculated SNR over the time period exceeds the predetermined threshold. For example, during a mechanical failure event, the SNR increases over a short period of time because the speed of the rotating pumping device 50 decreases due to a failure of a pump part (e.g., a bearing failure). The evaluation device 100 may determine whether a mechanical failure event has occurred by determining whether the increase in SNR over a time period exceeds a threshold. The time period may be any time period established by the user. For example, the time period may be greater than one minute. In other examples, the time period may be between about one minute and about five minutes or between about five minutes and about ten minutes. As shown with respect to fig. 3, because the motor current is greater than zero (the rotary pumping device 50 is running) and the SNR increases (2000) for a short period of time greater than a threshold (1750), the evaluation device 100 may determine that a fault event 306 has occurred.

If the evaluation device 100 determines that the increase in the calculated SNR does not exceed the predetermined threshold over the time period, the method 700 ends at step 716. However, if the evaluation device 100 determines that the increase in SNR calculated over a period of time exceeds a predetermined threshold, the method 700 continues to step 718.

At step 718, the assessment device 100 generates and outputs an indicator associated with the mechanical fault event. For example, if the evaluation device 100 determines that a mechanical failure event has occurred, the evaluation device 100 may generate and output an indicator associated with the mechanical failure event. The indicator may be displayed on the display screen 101. The device 100 may also send a control signal to turn off the motor in response to the determination.

Figures 8-9 show data collected from a blood pump system having a mechanical failure. Fig. 8 shows seven illustrative graphs representing data collected from a blood pump system. Graph 804 shows the SNR of the optical sensor (without units), graph 806 shows the raw purge flow (mL/hr), graph 808 shows the placement signal (mmHg), graph 810 shows the motor current (mA), graph 812 shows the motor speed (rpm), graph 814 shows the pump flow (L/min), and graph 816 shows the alarm occurrence (alarm number). Graphs 804 through 816 are shown on the same time scale and start at the same time (3/7/2019, 12:31: 34). At time 802, the SNR (shown in graph 804) increases significantly relative to the SNR prior to time 802. Prior to time 802, the average SNR was about 2500, the maximum was about 6000, and the minimum was about 1000. After time 802, the average SNR is about 5000, the maximum value exceeds 8000, and the minimum value is about 1000. At time 802, the motor current (as shown in graph 810) also increases rapidly over a short period of time, jumping from an average of about 760mA before time 802 (with a maximum of about 830mA and a minimum of about 690mA) to an average of about 850mA after time 802 (with a maximum of over 1000mA and a minimum of about 780 mA). The magnitude of the pump flow variance (shown in graph 814) also decreases at time 802, from an average magnitude of about 1L before time 802 to an average magnitude of about 0.2L after time 802. These increases in SNR and motor current at time 802 represent a mechanical problem or instability in the blood pump system-a problem that is timely related to bearing failure, subsequently leading to motor failure as shown in fig. 9 and described below.

Fig. 9 is a continuation of the graph shown in fig. 8 (beginning on day 7/3/2019, 14:52:57, where the x-axis of the graph shown in fig. 8 ends). Plot 904 shows a continuation of the SNR of plot 804, plot 906 shows a continuation of the raw purge flow signal of plot 806, plot 908 shows a continuation of the put signal of plot 808, and plot 910 shows a continuation of the motor current signal of plot 810. Graph 912 shows a continuation of the motor speed signal of graph 812, graph 914 shows a continuation of the pump flow signal of graph 814, and graph 916 shows a continuation of the alarm occurrence signal of graph 816. At time 902, a motor in the blood pump system fails. As can be seen in FIG. 9, when the motor fails (after a bearing failure at time 802), the SNR increases, the placement signal decreases, the motor current decreases to approximately zero mA, the motor stops running (motor speed goes to zero rpm), the pump flow stops, and an alarm is triggered (as shown in graph 916). The increase in SNR and motor current at time 802 indicates that the blood pump system has a mechanical failure approximately one hour prior to the motor failure at time 902. At least one benefit of identifying an increase in SNR and motor current (e.g., at time 802) is earlier and more reliable detection of mechanical problems and instabilities in the blood pump system. In some implementations, such increases in SNR and motor current, or both, may trigger alarms, motor shutdown, or prompt a user to remove (and in some cases replace) the blood pump system before the motor fails. .

In view of the foregoing, those of ordinary skill in the art will appreciate that the present disclosure provides for the use of fiber optic sensors as diagnostic tools to assess the performance and status of catheter-based medical devices. Although the embodiments and features described herein are particularly described for use in connection with a percutaneous heart pump system, it will be understood that the parts and other features outlined below may be combined with one another in any suitable manner and may be adapted and applied to other types of medical devices, such as electrophysiology research and catheter ablation devices, angioplasty and stenting devices, angiographic catheters, peripherally inserted central catheters, central venous catheters, midline catheters, peripheral catheters, inferior vena cava filters, abdominal aortic aneurysm treatment devices, thrombectomy devices, TAVR delivery systems, cardiac therapy and cardiac assist devices, including balloon pumps, cardiac assist devices implanted using surgical incisions, and any other vein or artery based endoluminal introduction catheters and devices.

The foregoing is merely illustrative of the principles of the present disclosure and the systems, methods and apparatus may be practiced in other ways than the described embodiments, which are presented for purposes of illustration and not of limitation. It should be understood that the systems, methods, and devices disclosed herein, while shown for use in a system percutaneous heart pump, may be applied to systems, methods, and devices for other implantable heart pumps or implantable heart assist devices.

Variations and modifications will occur to those skilled in the art upon review of the present disclosure. The various features described or illustrated above, including any components thereof, may be combined or integrated in other systems. Also, certain features may be omitted or not implemented. The various embodiments described or illustrated above may be combined in any manner.

Examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and made a part of this application.