Information processing device and catheter system

Abstract

Provided are: a balloon catheter; a fluid handling device that performs at least one of the supplying of a use fluid to be used for the balloon catheter and the discharging of the use fluid from the balloon catheter; a plurality of measuring electrodes for causing an alternating current to flow through the use fluid in the balloon catheter or the fluid handling device; an impedance measuring instrument that measures an impedance measurement value for the use fluid by causing an alternating current to flow through the use fluid by using the plurality of measuring electrodes; and an information processing device. The information processing device is provided with: an impedance acquisition unit 40 that acquires the impedance measurement value of the use fluid measured by the impedance measuring instrument; and a determination unit 50 that determines, on the basis of the impedance measurement value, whether a preset abnormality occurrence condition indicating that an abnormality has occurred is met.

Description

Information Processing Apparatus and Catheter System

[0001] The present disclosure relates to a catheter system including a balloon catheter, and an information processing apparatus used therefor.

[0002] Patent Document 1 discloses a balloon catheter including a shaft, a balloon provided on the shaft, and a heating member capable of heating a fluid supplied into the balloon.

[0003] International Publication No. 2023 / 120680

[0004] There are cases where it is desired to grasp the occurrence of any abnormality when using a balloon catheter. The inventor of the present application has conceived a technique capable of grasping the occurrence of an abnormality by a novel method.

[0005] One object of the present disclosure is to provide a novel technique capable of grasping the occurrence of an abnormality when using a balloon catheter.

[0006] One aspect of the present disclosure is a catheter system. The catheter system comprises: a balloon catheter having a shaft, a balloon provided on the shaft, and a heating member capable of heating a fluid supplied into the balloon; a fluid handling device that performs at least one of supplying a working fluid used for the balloon catheter and discharging the working fluid from the balloon catheter; a plurality of measurement electrodes for passing an alternating current through the working fluid inside any one of the balloon catheter and the fluid handling device; an impedance measuring device that measures an impedance measurement value of the working fluid by passing the alternating current through the working fluid using the plurality of measurement electrodes; and an information processing apparatus, wherein the information processing apparatus comprises: an impedance acquisition unit that acquires the impedance measurement value of the working fluid used for the balloon catheter, the impedance measurement value being measured by the impedance measuring device; and a determination unit that determines whether or not a predetermined abnormality occurrence condition indicating that an abnormality has occurred is satisfied based on the impedance measurement value.

[0007] Another aspect of the present disclosure is an information processing device. This information processing device is used in a catheter system comprising a balloon catheter, wherein the balloon catheter comprises a shaft, a balloon provided on the shaft, and a heating member capable of heating the fluid supplied into the balloon, and comprises an impedance acquisition unit that obtains an impedance measurement value of the working fluid used in the balloon catheter, measured by an impedance measuring instrument, and a determination unit that determines whether or not predetermined abnormality conditions indicating that an abnormality has occurred are met based on the impedance measurement value.

[0008] According to this disclosure, it will be possible to detect the occurrence of abnormalities when using balloon catheters.

[0009] This is a configuration diagram showing the catheter system of the embodiment. This is a schematic cross-sectional view showing a part of the balloon catheter of the embodiment. This is a block diagram showing the functions of a part of the catheter system of the embodiment. This is a graph showing the relationship between impedance and temperature. This is a flowchart showing an example of the operation related to the determination process of the embodiment. This is an explanatory diagram regarding the leakage current generated in the balloon catheter.

[0010] Embodiments for implementing the catheter system of this disclosure are described below. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. For the sake of clarity, components are omitted, enlarged, or reduced in each drawing. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0011] Refer to Figure 1. The catheter system 10 comprises a balloon catheter 12, a fluid handling device 14, a plurality of measuring electrodes 16, a temperature measuring device 26 (not shown in Figure 1), and an information processing unit 30. Hereinafter, the fluid actually used in the balloon catheter 12 will be referred to as the working fluid. This working fluid may include, for example, gases, liquids, and semi-solid substances such as gels. This working fluid may, for example, be a reversible thermogelling substance that is liquid at room temperature and gels into a semi-solid substance when heated. This refers to, for example, a contrast agent to which methylcellulose has been added. Specific examples of the working fluid are not limited to these; for example, in addition to various other contrast agents, physiological saline, sterile water, and other liquids, various gases such as air may also be used.

[0012] Refer to Figures 1 and 2. The balloon catheter 12 comprises a shaft 20, a balloon 22 provided on the shaft 20, at least one heating member 24 capable of heating the fluid supplied into the balloon 22, and a handle device 28 provided on the proximal portion of the shaft 20 and grasped by the operator.

[0013] The balloon catheter 12 is used for treating biological tissue. The surface temperature of the balloon 22 is adjusted by heating the working fluid inside the balloon 22 with the heating element 24. The treatment with the balloon catheter 12 is performed by bringing the balloon 22, whose surface temperature has been adjusted, into contact with biological tissue. The treatment here is, for example, ablation, but is not limited to any specific example.

[0014] The shaft 20 is inserted into the body at least in its distal portion and is flexible enough to be bent and deformed. The shaft 20 is constructed using at least one shaft member 20a, 20b. The shaft members 20a, 20b in this embodiment include an outer shaft member 20a and an inner shaft member 20b disposed within a lumen 20c formed in the outer shaft member 20a.

[0015] The balloon 22 is expandable by the fluid supplied inside. The balloon 22 is attached to the shaft 20 by welding, adhesive, or the like in at least a portion of it, and is supported by the shaft 20. The type of balloon 22 is not particularly limited, and various types of balloons such as compliant balloons and non-compliant balloons may be used.

[0016] The heating element 24 functions as an electrode for heating by an electric heating method. The heating element 24 is placed inside the balloon 22. The balloon catheter 12 in this embodiment includes at least two heating elements 24 provided at intervals in the axial direction of the shaft 20 inside the balloon 22. The heating elements 24 may be fixed to the shaft 20 by various fixing means such as bonding, welding, or swaging.

[0017] Refer to Figure 1. The fluid handling device 14 performs at least one of the following: supplying the working fluid to the balloon catheter 12 and discharging the working fluid from the balloon catheter 12. The fluid handling device 14 is composed of, for example, a syringe, a pump, etc. In this embodiment, an example is described in which the fluid handling device 14 performs both supplying and discharging the working fluid, but it may also perform only one of these functions. The fluid handling device 14 that supplies the working fluid and the fluid handling device 14 that discharges the working fluid may exist separately. In this embodiment, the fluid handling device 14 can supply fluid into the balloon 22 via the handle device 28 and the lumen 20c of the shaft 20. In this embodiment, the fluid handling device 14 can discharge fluid outside the balloon catheter 12 by drawing the fluid inside the balloon 22 through the handle device 28 and the lumen 20c of the shaft 20.

[0018] Multiple measuring electrodes 16 are used to pass an alternating current through the working fluid inside either the balloon catheter 12 or the fluid handling device 14. In this embodiment, the measuring electrodes 16 are used to pass an alternating current through the working fluid inside the balloon catheter 12, but they may also be used to pass an alternating current through the working fluid inside the fluid handling device 14. In this embodiment, the measuring electrodes 16 are provided inside the balloon 22. In this embodiment, the measuring electrodes 16 also serve as heating members 24, but they may be provided separately from the heating members 24. It can also be said that each of the two measuring electrodes 16 serves as each of the two heating members 24.

[0019] Multiple measuring electrodes 16 may be provided on either the balloon catheter 12 or the fluid handling device 14. In this case, the working fluid inside either the balloon catheter 12 or the fluid handling device 14 is mainly present in the current flow path between the multiple measuring electrodes 16. Alternatively, one measuring electrode 16 may be provided inside the balloon catheter 12, and the other measuring electrodes 16 may be provided on a counter electrode plate located outside the body. In this case, in addition to the working fluid inside the balloon catheter 12, bodily fluids, biological tissue, etc., outside the balloon catheter 12 may also be present in the current flow path between the multiple measuring electrodes 16. In any case, the multiple measuring electrodes 16 should be positioned so that an alternating current can be passed through the working fluid inside either the balloon catheter 12 or the fluid handling device 14.

[0020] Refer to Figure 3. Figure 3 is a block diagram showing a part of the configuration of the catheter system 10. Each block is composed of a combination of hardware elements and software elements, or either hardware elements or software elements. Each block may be realized in various ways through the coordination of these elements. Each block may be realized by common hardware elements or software elements, or by separate hardware elements or software.

[0021] The temperature measuring device 26 includes a temperature detection unit 26a that detects an electrical signal indicating the temperature of the balloon 22 or the fluid inside the balloon 22, and a signal processing unit 26b that processes the electrical signal detected by the temperature detection unit 26a to obtain a temperature measurement value indicating the temperature of the balloon 22 or the fluid inside the balloon 22. The temperature detection unit 26a is configured using, for example, a thermocouple, a thermistor, etc. The temperature detection unit 26a only needs to be able to detect an electrical signal indicating the temperature of the balloon 22 or the fluid inside the balloon 22, and its specific example and specific placement location are not particularly limited. In this embodiment, an example is shown in which the temperature detection unit 26a is placed inside the balloon 22, and the temperature measuring device 26 obtains a temperature measurement value indicating the temperature of the fluid inside the balloon 22. In addition, the temperature detection unit 26a may be placed outside the balloon 22, for example, or between the layers of a two-layer balloon 22. In this case, the temperature measuring device 26 can obtain a temperature measurement value indicating the temperature of the balloon 22. The temperature detection unit 26a may be attached to either the shaft 20 or the balloon 22. The signal processing unit 26b is electrically connected to the temperature detection unit 26a via wiring (not shown) provided inside the handle device 28 and the shaft 20. The signal processing unit 26b converts the electrical signal into a digital signal by AD conversion and then performs various signal processing such as scaling to obtain the temperature measurement value. The signal processing unit 26b is shown as being incorporated as part of the information processing device 36, but it may also be provided separately from the information processing device 36. The temperature measuring instrument 26 uses the temperature detection unit 26a and the signal processing unit 26b to measure a temperature measurement value indicating the temperature of the balloon 22 or the fluid inside the balloon 22 at regular measurement intervals, for example.

[0022] The information processing unit 30 includes a power supply 32 that supplies power to the heating element 24, an impedance measuring instrument 34 that measures the impedance of the fluid being used using a plurality of measuring electrodes 16, and an information processing device 36. In this embodiment, the information processing unit 30 is configured as a console that integrates the power supply 32, the impedance measuring instrument 34, and the information processing device 36. Alternatively, the information processing device 36 may be provided separately from the power supply 32 and the impedance measuring instrument 34.

[0023] The power supply 32 is composed of, for example, a power supply circuit such as a regulator. The power supply 32 is electrically connected to the heating element 24 via a connector 28a provided on the handle device 28 and wiring (not shown) provided inside the handle device 28 and the shaft 20. The power supply 32 supplies power to the heating element 24 in a manner corresponding to the heating method of the heating element 24. The heating method of the heating element 24 in this embodiment is a bipolar heating method. The bipolar heating method here refers to a method in which the fluid inside the balloon 22 is heated by Joule heat generated by passing current between a plurality of heating elements 24. In this case, the power supply 32 supplies power so that current is passed between the plurality of heating elements 24. The heating method of the heating element 24 is not particularly limited, and a monopolar heating method in which the fluid is heated by passing current between an external counter electrode plate and the heating element 24 may also be used. The bipolar heating method, monopolar heating method, etc., are direct resistance heating methods in which the fluid is directly heated by Joule heat generated in the fluid inside the balloon 22. In addition to the heating method described above, the heating method for the heating element 24 may also be an indirect resistance heating method, in which the fluid is indirectly heated by the Joule heat generated in the heating element 24. In this embodiment, the power supply 32 applies an AC voltage to the multiple heating elements 24, thereby allowing an AC current to flow through the working fluid between the multiple heating elements 24 using the heating elements 24.

[0024] The impedance meter 34 may be composed of, for example, an impedance monitor, an LCR meter, etc. The impedance meter 34 is electrically connected to the measuring electrode 16. When the measuring electrode 16 is provided inside the balloon 22, the impedance meter 34 is electrically connected to the measuring electrode 16 via a connector 28a provided on the handle device 28 and wiring (not shown) provided inside the handle device 28 and the shaft 20. The impedance meter 34 can flow an alternating current through the working fluid between the multiple measuring electrodes 16 by applying an alternating voltage to the multiple measuring electrodes 16. Based on the response when the alternating current is flowed in this way, the impedance meter 34 can measure the impedance measurement value (hereinafter also referred to as the impedance measurement value of the working fluid) that indicates the impedance of the working fluid. The impedance meter 34 measures the impedance measurement value of the working fluid by flowing an alternating current through the working fluid using the multiple measuring electrodes 16. The impedance meter 34 measures the impedance measurement value by flowing an alternating current through the working fluid when the balloon 22 is not ruptured.

[0025] The information processing device 36 functions as a computer. The hardware elements of the information processing device 36 include, for example, a processor, ROM (Read Only Memory), and RAM (Random Access Memory). The software elements of the information processing device 36 include, for example, an operating system and applications.

[0026] The information processing device 36 includes a temperature acquisition unit 38 that acquires temperature measurements of the balloon 22 or the working fluid measured by a temperature measuring instrument 26, and an impedance acquisition unit 40 that acquires impedance measurements of the working fluid measured by an impedance measuring instrument 34. In addition, the information processing device 36 includes a processing unit 42 that performs various processing, an operation unit 44 for performing various operations, and a storage unit 46 for storing various information. The processing unit 42 includes a control unit 48 that controls heating by the heating element 24, and a determination unit 50 that performs determination processing based on the impedance measurement value. The operation unit 44 includes a power operation unit 44A for switching the power of the information processing unit 30 on and off, and a heating start operation unit 44B for performing a heating start operation to start heating. Each operation unit 44, 44A, and 44B is composed of, for example, buttons, dials, touch panels, etc.

[0027] The temperature acquisition unit 38 is electrically connected to the temperature measuring instrument 26. The temperature acquisition unit 38 acquires the temperature measurement value by receiving the temperature measurement value that is periodically and repeatedly sent from the temperature measuring instrument 26.

[0028] The impedance acquisition unit 40 is electrically connected to the impedance measuring instrument 34. The impedance acquisition unit 40 acquires the impedance measurement value by receiving the impedance measurement value that is periodically and repeatedly sent from the impedance measuring instrument 34.

[0029] The control unit 48 is electrically connected to the power supply 32. The control unit 48 controls the heating of the working fluid by the heating element 24 by controlling the power supplied from the power supply 32 to the heating element 24. To achieve this, the control unit 48 controls the output, heating time, etc., of the heating element 24. Here, output refers to the heating force of the working fluid by the heating element 24, and may be expressed as the amount of heat (W) imparted to the object by that heating.

[0030] The control unit 48 performs temperature maintenance control, controlling the heating by the heating element 24 so that the temperature measurement value acquired by the temperature acquisition unit 38 approaches a preset target temperature value. In this embodiment, the heating of the working fluid for temperature maintenance control by the control unit 48 is started by a user's heating start operation on the heating start operation unit 44B. The heating start operation here refers to, for example, pressing a switch. The target temperature value may be a variable value set by the user's operation on the operation unit 44, or it may be a predetermined fixed value. By performing temperature maintenance control by the control unit 48, the temperature measurement value of the balloon 22 or the working fluid is maintained within a temperature range near the target temperature value. The control unit 48 performs this temperature maintenance control until the elapsed time since the start of temperature maintenance control exceeds a preset time. The preset time is set to the time necessary to obtain an effect suitable for treatment using the balloon catheter 12.

[0031] The determination unit 50 performs a determination process to determine whether or not a predetermined abnormality occurrence condition, which indicates that an abnormality has occurred, is met, based on the impedance measurement value obtained by the impedance acquisition unit 40. In this embodiment, an abnormality that is subject to determination by the abnormality occurrence condition is when the impedance measurement value of the fluid being used falls outside the normal range predetermined as the range of normal impedance measurement values. In order to determine such an abnormality, the abnormality occurrence condition in this embodiment is that the impedance measurement value is outside the normal range. Normal range identification information that identifies this normal range is stored in the storage unit 46. The determination unit 50 determines whether or not the impedance measurement value is within the normal range identified from the normal range identification information stored in the storage unit 46.

[0032] The fluid predetermined to be used in the balloon catheter 12 is called the appropriate fluid. The aforementioned normal range may be predetermined as the range in which the impedance measurement value of the appropriate fluid can take place. If a fluid other than the appropriate fluid is mistakenly used as the fluid to be used, the impedance measurement value of the fluid to be used may fall outside the normal range thus defined. In this case, the occurrence of such fluid misuse will be included in the abnormalities that will be identified based on the abnormality occurrence conditions.

[0033] Refer to Figure 4. The magnitude of the fluid impedance changes depending on the fluid temperature, with the impedance decreasing as the temperature increases. Based on this, the determination unit 50 may determine whether the abnormality conditions are met based on the temperature measurement value obtained by the temperature acquisition unit 38, in addition to the impedance measurement value. To achieve this, the abnormality conditions may be defined as being outside the normal range R, which is determined according to the temperature measurement value, as described above. This normal range R may be predetermined as the range that the impedance measurement value of an appropriate fluid can take when any temperature measurement value is within a predetermined temperature range. In this case, the determination unit 50 identifies the normal range R of the impedance measurement value when the temperature measurement value is obtained, based on relational information showing the relationship between the normal range R of the impedance measurement value and the temperature measurement value. After this, the determination unit 50 determines whether the obtained impedance measurement value is within the identified normal range R.

[0034] Relationship information showing the relationship between the normal range R of impedance measurements and temperature measurements is stored in the storage unit 46 as the aforementioned normal range identification information. This relationship information is identified, for example, by a relationship formula, a table, etc. Here, an example is shown in which this relationship information is identified by a relationship formula Eq1 that defines an upper threshold and a relationship formula Eq2 that defines a lower threshold. In this case, the normal range R is defined as the range between the upper threshold defined by relationship formula Eq1 and the lower threshold defined by relationship formula Eq2. In addition, the normal range R may also be defined as a range below the upper threshold using only the upper threshold, or a range above the lower threshold using only the lower threshold.

[0035] The normal range R may be set based on the results of experiments, simulations, etc. For example, a relational equation Eq0 showing the relationship between the appropriate fluid temperature and impedance may be estimated based on experiments, simulations, etc., and a predetermined range based on this relational equation Eq0 may be set as the normal range R. Here, an example is shown in which the measured value P of the appropriate fluid impedance at a specific temperature is obtained in advance, and the relational equation Eq0 is estimated using various estimation methods such as interpolation, extrapolation, and regression based on the obtained measured value P. The impedance changes depending on the size of the balloon 22 and the size of the measuring electrode 16. Taking this into consideration, the size of the predetermined range based on the relational equation Eq0 at an arbitrary temperature may be, for example, a range within ±10% of the impedance value at an arbitrary temperature specified from the relational equation Eq0. Furthermore, as shown in Figure 4, the upper and lower thresholds that define the normal range R may be set so that they become smaller as the measured temperature of the balloon 22 or the fluid increases.

[0036] The control unit 48 may control heating by the heating element 24 based on the determination result of the determination unit 50. Here, a first control mode of the control unit 48 using such determination result of the determination unit 50 will be described. Consider the case where the heating is stopped, and heating of the working fluid by the heating element 24 is stopped. In this heating stopped state, if the determination unit 50 determines that the abnormal occurrence conditions are not met, the control unit 48 may start heating by the heating element 24, assuming that the predetermined heating start conditions are met. Also, in the heating stopped state, the control unit 48 does not have to start heating by the heating element 24 even if the determination unit 50 determines that the abnormal occurrence conditions are met or if the heating start conditions are met. The heating start conditions here refer to, for example, the user performing a heating start operation on the heating start operation unit 44B.

[0037] The information processing device 36 may include a notification unit 52 that notifies the determination result of the determination unit 50. This allows the user to understand the determination result of the determination unit 50. The notification unit 52 may be configured as a lamp, display, etc. that notifies in a visually recognizable manner, or as a speaker, etc. that notifies in an audibly recognizable manner. The notification unit 52 may notify the determination result of the determination unit 50 in at least one of the following cases: (1) when the determination unit 50 determines that the conditions for an abnormality have been met, or (2) when the determination unit 50 determines that the conditions for an abnormality have not been met. In this embodiment, the notification unit 52 notifies that an abnormality has occurred in case (1).

[0038] Next, an example of the operation of the catheter system 10 described above will be explained. Figure 5 is a flowchart of an example of the operation related to the determination process. First, the balloon 22 of the shaft 20 is transported to the treatment site of the living body using a delivery catheter or the like. Also, the balloon 22 is expanded by supplying fluid into the balloon 22. After this, when the impedance measuring instrument 34 satisfies the predetermined measurement start conditions, it starts measuring the impedance measurement value of the fluid being used using the measuring electrode 16 (S10). In this embodiment, the measurement start condition is that the power of the information processing unit 30 is switched on by the power operation unit 44A. The impedance acquisition unit 40 receives the impedance measurement value that is periodically and repeatedly sent from the impedance measuring instrument 34 and acquires the impedance measurement value.

[0039] Subsequently, when the heating start condition is met (S12), the determination unit 50 performs a determination process to determine whether or not the abnormality occurrence condition is met based on the impedance measurement value acquired by the impedance acquisition unit 40 (S14). If the determination unit 50 determines that the abnormality occurrence condition is not met (N in S14), the control unit 48 starts heating with the heating element 24 (S16). Here, the control unit 48 performs the temperature maintenance control described above. The subsequent processing will be omitted from the explanation. On the other hand, if the determination unit 50 determines that the abnormality occurrence condition is met (Y in S14), the control unit 48 does not start heating with the heating element 24 (S18). At the same time, the notification unit 52 notifies that an abnormality has occurred (S18). This completes the processing.

[0040] The effects of the catheter system 10 and the information processing device 36 described above will now be explained.

[0041] The information processing device 36 includes a determination unit 50 that determines whether or not the conditions for an abnormality to occur are met based on the impedance measurement value. Therefore, the determination result of the determination unit 50 can be used to identify the occurrence of an abnormality when using the balloon catheter 12. In particular, by performing the determination process based on the impedance measurement value, it is effective in identifying the misuse of fluids, such as the use of a fluid other than the appropriate fluid.

[0042] The control unit 48 of the information processing device 36 controls heating by the heating element 24 based on the determination result of the determination unit 50. This allows the determination result of the determination unit 50 to be reflected in the control of heating by the heating element 24.

[0043] If the determination unit 50 determines that an abnormality occurrence condition is satisfied, the control unit 48 does not start heating by the heating member 24. This makes it possible to prevent the occurrence of malfunctions caused by starting heating when an abnormality that is a target of determination based on the abnormality occurrence condition has occurred. Suppose a case where the abnormality targeted for determination based on the abnormality occurrence condition is the aforementioned misuse of fluid. In this case, a situation in which a used fluid different from a proper fluid is heated by the heating member 24 can be avoided. Therefore, when the viscosity, specific heat, etc. of the used fluid are greatly different from those of the proper fluid, the occurrence of malfunctions caused by heating the used fluid can be avoided. The malfunctions herein include, for example, a rapid temperature rise caused by the specific heat of the used fluid being larger than that of the proper fluid, and temperature unevenness caused by the viscosity of the used fluid being larger than that of the proper fluid.

[0044] The abnormality occurrence condition is that the measured impedance value is outside the normal range. This makes it possible to stably avoid malfunctions caused by the measured impedance value being outside the normal range. For example, when the measured impedance value is larger than the normal range, it becomes difficult for an alternating current to flow through the used fluid, which may cause a delay in temperature rise. Also, when the measured impedance value is smaller than the normal range, an alternating current easily flows through the used fluid, which may cause an abnormal temperature rise. According to the present embodiment, these malfunctions can be stably avoided.

[0045] The impedance of a fluid has temperature dependency that depends on temperature. In this regard, the determination unit 50 of the present embodiment determines whether an abnormality occurrence condition is satisfied based on the measured impedance value and the measured temperature value. By using the measured temperature value in addition to the measured impedance value in this way, the occurrence of an abnormality can be accurately grasped in consideration of the temperature dependency of the impedance of the fluid.

[0046] The measurement electrode 16 also serves as the heating member 24. This makes it possible to reduce the number of parts of the entire catheter system 10 compared to a case where the measurement electrode 16 and the heating member 24 are separate bodies.

[0047] Each of the two measurement electrodes 16 also serves as each of the two heating members 24. Accordingly, the working fluid is heated by a bipolar heating method, and uneven temperature of the fluid in the balloon 22 can be suppressed as compared with a monopolar heating method. In addition, since the two heating members 24 used in the bipolar heating method also serve as separate measurement electrodes 16, when an alternating current is passed through the working fluid by each measurement electrode 16 to measure an impedance measurement value, it is possible to avoid passing objects other than the working fluid (for example, body fluid, etc.) through the energization path between the respective measurement electrodes 16 as much as possible. Therefore, it becomes less susceptible to the influence of the impedance of objects other than the working fluid, which is advantageous for accurately determining whether or not an abnormality to be determined based on an abnormality occurrence condition has occurred.

[0048] Next, other features of the catheter system 10 will be described. The power source 32 heats the working fluid by passing an alternating current of a first frequency f1 (Hz) through the working fluid using the heating member 24 under the control of the control unit 48. The impedance measuring device 34 may measure an impedance measurement value of the working fluid by passing an alternating current of a second frequency f2 (Hz), which is smaller than the first frequency f1, through the working fluid using the plurality of measurement electrodes 16. This advantage will be described below.

[0049] As a result of continued studies, the inventor of the present application has newly recognized the following. Reference is made to FIG. 6. FIG. 6 schematically shows a part of the balloon catheter 12. The balloon catheter 12 includes a plurality of wires 60 connected to the plurality of measurement electrodes 16. The wire 60 includes a conductive wire and an insulating layer covering the conductive wire. The plurality of wires 60 are inserted through the lumen 20c of the outer shaft member 20a. The higher the frequency of the alternating current f is, the more easily the alternating current flows as a leakage current between the conductive wires of the wires 60 due to the influence of the stray capacitance of the fluid 62 existing between the wires 60. Here, an arrow is added to the flow direction of the current, and a portion where the leakage current occurs is indicated by a hollow arrow. When a leakage current flows, it behaves as if there is a resistance component connected in parallel with the working fluid between the measurement electrodes 16 between these wires 60. As the frequency f of the alternating current increases, this influence becomes larger, so that the impedance of the working fluid between the measurement electrodes 16 becomes less likely to be reflected in the impedance measurement value.

[0050] In this embodiment, the impedance measuring instrument 34 measures the impedance of the working fluid by passing an alternating current with a second frequency f2, which is smaller than the first frequency f1, through the working fluid. Therefore, compared to the case where an alternating current with the first frequency f1 is passed through the working fluid, leakage current is less likely to flow between the aforementioned wiring 60. As a result, the impedance of the working fluid between the measuring electrodes 16 is more easily reflected in the impedance measurement value, which is advantageous in accurately determining whether or not an abnormality, which is subject to discrimination based on the abnormality occurrence conditions, has occurred. In relation to this effect, it is preferable that the second frequency f2 is somewhat smaller than the first frequency f1. From this viewpoint, the second frequency f2 may be, for example, half or less of the first frequency f1. For example, the first frequency f1 may be 480 kHz and the second frequency f2 may be 80 kHz. Note that the second frequency f2 may be greater than or equal to the first frequency f1.

[0051] Next, a second control mode by the control unit 48 using the determination result of the determination unit 50 will be described. Consider the case where the working fluid inside the balloon 22 is heated at normal output by the heating member 24. In this heated state, the working fluid inside the balloon 22 may be replaced by discharging the working fluid inside the balloon 22 with one fluid handling device 14 and supplying new working fluid into the balloon 22 with another fluid handling device 14. At this time, the aforementioned misuse of fluid may occur if a fluid other than the appropriate fluid is mistakenly supplied into the balloon 22. Here, an example of using the second control mode in such a case will be described, but it may also be used in other cases.

[0052] When the system is in this heated state, the control unit 48 may continue heating with the heating element 24 at normal output if the determination unit 50 determines that the abnormal condition is not met. Alternatively, when the system is in this heated state, the control unit 48 may stop heating with the heating element 24 if the determination unit 50 determines that the abnormal condition is met. In addition, the control unit 48 may reduce the output of the heating element 24 instead of stopping heating. Reducing the output of the heating element 24 here means changing the output of the heating element 24 to a reduced output that is lower than the normal output. The reduced output may be set to be significantly smaller than the normal output. For example, the reduced output may be set so that the amount of heat (W) imparted to the fluid by heating with the heating element 24 at the reduced output is less than or equal to half the amount of heat imparted by heating with the heating element 24 at normal output.

[0053] This prevents the situation where the fluid being used is continuously heated at the same output by the heating element 24 when an abnormality that is subject to detection based on the abnormality occurrence conditions occurs. Let's assume that the abnormality that is subject to detection based on the abnormality occurrence conditions is the misuse of the fluid as described above. In this case, if the viscosity, specific heat, etc. of the fluid being used differ significantly from that of the appropriate fluid, it becomes possible to avoid malfunctions caused by continuously heating the fluid being used at the same output.

[0054] Next, we will describe the transformation forms of each component described so far.

[0055] The number of heating elements 24 is not particularly limited; there may be three or more, or just one. The number of temperature measuring devices 26 is not particularly limited; there may be two or more. When multiple temperature measuring devices 26 are used, the control unit 48 may use the highest temperature measurement value among the multiple temperature measurements taken by the multiple temperature measuring devices 26 to maintain the temperature. The temperature measuring device 26 for measuring the temperature measurement value used in the judgment process is provided in either the balloon catheter 12 or the fluid handling device 14, and it is sufficient that it can measure a temperature measurement value indicating the temperature of the working fluid or balloon 22 inside either of them.

[0056] The control unit 48 may control the heating of the heating element 24 without using the determination result of the determination unit 50. The control unit 48 may be able to execute only one of the first and second control modes described above, or it may be able to execute both.

[0057] The determination unit 50 only needs to be able to determine whether or not the abnormality conditions are met based on the impedance measurement value, and the specific processing method for this is not particularly limited. The determination unit 50 may also determine whether or not the abnormality conditions are met without using the temperature measurement value. Furthermore, if the determination unit 50 uses the temperature measurement value as well for the determination process, the specific processing method for this is not particularly limited. An example has been described in which the normal range is defined as the range that the impedance measurement value of the appropriate fluid can take, but it may also be defined as a range other than this. For example, when heating with the heating member 24, the way the temperature of the fluid used rises changes depending on the impedance measurement value of the fluid used. The normal range may be defined as a range suitable for an appropriate temperature rise. The determination unit 50 may select the appropriate fluid by operating the operation unit 44 and determine whether or not the abnormality conditions corresponding to the selected appropriate fluid are met.

[0058] Up to this point, we have described an example in which the determination unit 50 performs a determination process using an impedance measurement value corresponding to a single current path, obtained by passing an alternating current through a single current path between two measuring electrodes 16. However, the determination process is not limited to this, and the determination process may also be performed using multiple impedance measurement values ​​corresponding to each current path, obtained by individually passing an alternating current through multiple current paths between different combinations of measuring electrodes 16. In this case, the control unit 48 may perform the various processes described above when it determines that the abnormality occurrence conditions have been met based on at least one impedance measurement value among the multiple impedance measurement values ​​corresponding to each current path. In addition, the control unit 48 may perform the various processes described above when it determines that the abnormality occurrence conditions have been met based on two or more impedance measurement values ​​among the multiple impedance measurement values ​​corresponding to each current path. The various processes here refer to stopping heating by the heating element 24, reducing its output, and notifying the occurrence of an abnormality by the notification unit 52. In this case, the two measuring electrodes 16 that form one current path and the two measuring electrodes 16 that form the other current paths do not have to overlap, or only one may overlap.

[0059] The relationship between the first heating frequency f1 and the second impedance measurement frequency f2 described above (for example, f1 > f2) may be combined with the second control mode described above. In this case, when the working fluid is heated by passing an alternating current of the first frequency f1 using the heating element 24, the impedance measurement value of the working fluid is measured by passing an alternating current of the second frequency f2 using the measuring electrode 16. In other words, an alternating current of the first frequency f1 for heating and an alternating current of the second frequency f2 for impedance measurement are passed simultaneously. As a first embodiment to realize this, a mode may be adopted in which an alternating current containing the components of the first heating frequency f1 and the second impedance measurement frequency f2 is passed through the working fluid using a pair of measuring electrodes 16 that also serve as the heating element 24. In addition, as a second embodiment to realize this, a mode may be adopted in which an alternating current of the first frequency f1 is passed through using a pair of heating elements 24, while an alternating current of the second frequency f2 is passed through using a dedicated pair of measuring electrodes 16 different from the heating element 24.

[0060] In the first embodiment, a filter such as a low-pass filter incorporated in the impedance measuring instrument 34 may be used to remove the component of the first frequency f1 included in the response obtained by passing the aforementioned AC current through the working fluid, and only the component of the second frequency f2 may be extracted. Then, the impedance measurement value of the working fluid may be obtained using the extracted component of the second frequency f2.

[0061] When the second embodiment is adopted, passing an alternating current of the first frequency f1 through the wiring for the heating element may cause leakage current to occur between the wiring for the heating element and the wiring for the measuring electrode. Therefore, in order to reduce the effect of this leakage current, it is advisable to place the wiring for the heating element and the wiring for the measuring electrode as far apart as possible, or to use the aforementioned filter. Here, the wiring for the heating element refers to the wiring electrically connected to the heating element 24, and the wiring for the measuring electrode refers to the wiring electrically connected to the measuring electrode 16.

[0062] The contents of each component described in the embodiments above are illustrative. The abstract technical ideas derived from these should not be interpreted restrictively to the contents of this specification. Many design changes, such as modifications, additions, and deletions, are possible for the contents of each component described in the embodiments. Such modifications are emphasized with the notations "this form" and "embodiment." However, design changes are also permitted for contents without such notations. Any combination of the above components is also valid. For example, any description of another embodiment may be combined with an embodiment, or any description of an embodiment and another variant may be combined with a variant. Furthermore, any substitution of any of the components and expressions of this disclosure between methods, apparatus, systems, etc., is also valid as an embodiment of this disclosure.

[0063] This disclosure relates to a catheter system comprising a balloon catheter.

[0064] 10...Catheter system, 12...Balloon catheter, 14...Fluid handling device, 16...Measurement electrode, 20...Shaft, 22...Balloon, 24...Heating element, 26...Temperature measuring instrument, 32...Power supply, 34...Impedance measuring instrument, 36...Information processing device, 38...Temperature acquisition unit, 40...Impedance acquisition unit, 48...Control unit, 50...Determination unit.

Claims

1. A catheter system comprising: a balloon catheter having a shaft, a balloon provided on the shaft, and a heating member capable of heating the fluid supplied into the balloon; a fluid handling device that supplies a working fluid to the balloon catheter and discharges the working fluid from the balloon catheter; a plurality of measuring electrodes for passing an alternating current through the working fluid inside either the balloon catheter or the fluid handling device; an impedance measuring instrument that measures the impedance measurement value of the working fluid by passing an alternating current through the working fluid using the plurality of measuring electrodes; and an information processing device, wherein the information processing device comprises: an impedance acquisition unit that obtains the impedance measurement value of the working fluid measured by the impedance measuring instrument; and a determination unit that determines whether or not predetermined abnormality conditions indicating that an abnormality has occurred are met based on the impedance measurement value.

2. The catheter system according to claim 1, wherein the information processing device includes a control unit that controls the heating of the working fluid by the heating member by controlling the power supplied to the heating member from a power source, and the control unit controls the heating by the heating member based on the determination result of the determination unit.

3. The catheter system according to claim 2, wherein the control unit is in a heating stop state in which heating by the heating member is stopped, and when the determination unit determines that the abnormality occurrence condition is met, the control unit does not start heating by the heating member.

4. The catheter system according to claim 2 or 3, wherein the control unit is in a heating state in which the working fluid is being heated by the heating member, and when the determination unit determines that the abnormal condition is met, the control unit stops heating by the heating member or reduces the output of the heating member.

5. The catheter system according to any one of claims 1 to 4, wherein the abnormality condition is that the impedance measurement value is outside a predetermined normal range.

6. The catheter system according to any one of claims 1 to 5, wherein the information processing device comprises a temperature acquisition unit that acquires a temperature measurement value of the balloon or the working fluid measured by a temperature measuring instrument, and the determination unit determines whether or not the abnormality occurrence condition is met based on the impedance measurement value and the temperature measurement value.

7. The catheter system according to claim 6, wherein the abnormality condition is that the impedance measurement value is within a predetermined normal range and outside the normal range determined according to the temperature measurement value.

8. A catheter system according to any one of claims 1 to 7, comprising a power supply that uses the heating member to supply alternating current to the working fluid, wherein the power supply heats the working fluid by supplying alternating current of a first frequency to the working fluid, and the impedance measuring instrument measures the impedance measurement value of the working fluid by supplying alternating current of a second frequency lower than the first frequency to the working fluid using a plurality of measuring electrodes.

9. An information processing device used in a catheter system equipped with a balloon catheter, wherein the balloon catheter comprises a shaft, a balloon provided on the shaft, and a heating member capable of heating the fluid supplied into the balloon, and the information processing device comprises an impedance acquisition unit that obtains an impedance measurement value of the working fluid used in the balloon catheter, measured by an impedance measuring instrument, and a determination unit that determines whether or not predetermined abnormality conditions indicating that an abnormality has occurred are met based on the impedance measurement value.

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