Catheter system

Abstract

This catheter system 1 comprises: an electrode catheter 4 that has a catheter electrode 14 on the distal-end side thereof and is inserted into the cardiac chamber; an external electrode 6 that is disposed on the body surface; a power supply unit 26 that is electrically connected to the catheter electrode 14 and the external electrode 6 and applies a voltage to the catheter electrode 14 and the external electrode 6; and a control unit 28 that controls the power supply unit 26 so as to apply a voltage for defibrillation between the catheter electrode 14 and the external electrode 6.

Description

Catheter System

[0001] The present disclosure relates to a catheter system.

[0002] Conventionally, an external defibrillator that applies defibrillation by applying electrodes to the patient's body surface is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2016-187438

[0004] In external defibrillation, there has been a problem that the success rate of defibrillation may decrease in patients in whom electrical energy for defibrillation is difficult to reach from outside the body, such as obese patients.

[0005] The present disclosure has been made in view of such circumstances, and its object is to provide a novel technique related to defibrillation treatment.

[0006] One aspect of the present disclosure is a catheter system. This catheter system includes an electrode catheter having a catheter electrode on the tip side and inserted into the heart cavity, an external electrode disposed on the body surface, a power supply unit electrically connected to the catheter electrode and the external electrode and applying a voltage to the catheter electrode and the external electrode, and a control unit that controls the power supply unit to apply a defibrillation voltage between the catheter electrode and the external electrode.

[0007] Any combination of the above components, and those obtained by converting the expression of the present disclosure among methods, apparatuses, systems, etc. are also effective as aspects of the present disclosure.

[0008] According to the present disclosure, a novel technique related to defibrillation treatment can be provided.

[0009] It is a schematic diagram of the catheter system according to Embodiment 1. It is a schematic diagram showing a state where the electrode catheter is inserted into the heart cavity. FIGS. 3(A), 3(B), and 3(C) are schematic diagrams for explaining the control executed by the control unit. It is a schematic diagram showing a state where a plurality of electrode catheters are inserted into the heart cavity in the catheter system according to Embodiment 2. FIGS. 5(A) and 5(B) are schematic diagrams for explaining the control executed by the control unit of the catheter system according to Embodiment 3.

[0010] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0011] (Embodiment 1) Figure 1 is a schematic diagram of a catheter system 1 according to Embodiment 1. In Figure 1, some of the components of the catheter system 1 are depicted as functional blocks. At least some of these functional blocks can be realized as hardware components and circuits, including the CPU and memory of a computer, and as software components, by computer programs, etc. It will be understood by those skilled in the art that these functional blocks can be realized in various ways by combining hardware and software. The catheter system 1 is used when performing defibrillation on a patient 2. The catheter system 1 comprises an electrode catheter 4, an external electrode 6, and a power supply device 8.

[0012] The electrode catheter 4, for example, has the form of a known defibrillation catheter or diagnostic catheter, and comprises a shaft 10, a handle 12, and a catheter electrode 14. The shaft 10 is, for example, a tubular body that is long in one direction, and at least its tip is inserted into the heart chamber of the patient 2. The shaft 10 can be made of a known flexible material. Various thin wires (not shown), such as conductors or pull wires, are inserted inside the shaft 10. The handle 12 is provided on the proximal end of the shaft 10 and is positioned outside the body when the electrode catheter 4 is in use, and is grasped and operated by the user. By operating the handle 12, the user can direct the tip of the shaft 10 in a predetermined direction. A power supply device 8 is electrically connected to the handle 12 via a connector (not shown).

[0013] The catheter electrode 14 is provided on the tip side of the shaft 10. The catheter electrode 14 is made of a metal or an alloy thereof with good conductivity. For example, the catheter electrode 14 is ring-shaped and extends around the entire circumference of the shaft 10. Alternatively, the catheter electrode 14 may extend only to a part of the circumferential direction of the shaft 10. The tip end of a conductor is connected to the catheter electrode 14. The conductor is passed through the inside of the shaft 10, and its proximal end is connected to the connector on the handle 12. This electrically connects the catheter electrode 14 and the power supply 8 via the conductor.

[0014] The electrode catheter 4 of this embodiment has a plurality of catheter electrodes 14. Figure 2 is a schematic diagram showing the electrode catheter 4 inserted into the cardiac chamber. For example, the plurality of catheter electrodes 14 can be divided into a first electrode group G1 and a second electrode group G2. In the example shown in Figure 2, the first electrode group G1 and the second electrode group G2 each contain eight catheter electrodes 14, but the number of catheter electrodes 14 belonging to each electrode group is not particularly limited and may be more than eight. Also, each electrode group may contain only one catheter electrode 14. In each electrode group, the plurality of catheter electrodes 14 are arranged in the axial direction of the electrode catheter 4 with a predetermined distance between them. The first electrode group G1 is positioned closer to the tip of the electrode catheter 4 than the second electrode group G2.

[0015] In the example shown in Figure 2, the electrode catheter 4 enters the right atrium (RA) from the superior vena cava (SVC) and extends into the coronary sinus (CS). The first electrode group G1 is positioned in the coronary sinus CS. The second electrode group G2 is positioned in the right atrium RA. The electrode catheter 4 may have three or more electrode groups. For example, a third electrode group may be provided in the superior vena cava (SVC) proximal to the second electrode group G2. Alternatively, the electrode catheter 4 may be inserted into the right atrium RA from the inferior vena cava (IVC).

[0016] Returning to Figure 1, the external electrodes 6 are placed on the body surface of the patient 2. There may be multiple external electrodes 6. In this embodiment, the external electrodes 6 include a first external electrode 6a and a second external electrode 6b. Hereinafter, when it is not necessary to distinguish between the first external electrode 6a and the second external electrode 6b, they may be simply referred to as "external electrodes 6". The external electrodes 6 are, for example, made up of patch electrodes and can be attached to the body surface of the patient 2. For example, the first external electrode 6a is attached to the right anterior chest, and the second external electrode 6b is attached to the left side of the chest. The external electrodes 6 are electrically connected to the power supply device 8 via a conductor.

[0017] The power supply unit 8 comprises an input unit 24, a power supply unit 26, a control unit 28, and a display unit 30. The input unit 24 is composed of, for example, a dial, buttons, a touch panel, etc., and is operated by the user of the catheter system 1. The user can input various setting values ​​and signals to instruct operations to the power supply unit 8 via the input unit 24. Note that various setting values ​​may be pre-set and stored in the power supply unit 8 at the time of product shipment, etc. Signals indicating the setting values, etc., are sent from the input unit 24 to the control unit 28.

[0018] The power supply unit 26 is electrically connected to the catheter electrode 14 and the external electrode 6. The power supply unit 26 can apply voltage to the catheter electrode 14 and the external electrode 6 according to control signals sent from the control unit 28. The power supply unit 26 is composed of a predetermined power supply circuit, such as a switching regulator. The control unit 28 controls the operation of the entire power supply device 8 and performs predetermined calculation processing. The control unit 28 is composed of a microcomputer, for example. The control unit 28 controls the application of voltage to the catheter electrode 14 and the external electrode 6 by sending control signals to the power supply unit 26. The display unit 30 displays various information to the outside. The display unit 30 is composed of a liquid crystal display, a CRT display, an organic EL display, etc.

[0019] The control unit 28 can acquire information regarding the patient's electrocardiogram waveform from the monitoring device 32. The monitoring device 32 acquires the patient's electrocardiogram waveform via the electrocardiogram measurement unit 34. Figure 1 schematically shows the arrangement of the electrocardiogram measurement unit 34. The electrocardiogram measurement unit 34 can be composed of patch electrodes attached to the surface of the patient's body or electrode catheters inserted into the patient's body. If electrode catheters 4 or external electrodes 6 can be used as the electrocardiogram measurement unit 34, the monitoring device 32 may acquire the electrocardiogram waveform via electrode catheters 4 or external electrodes 6. The monitoring device 32 sends the acquired electrocardiogram waveform to the control unit 28.

[0020] (Application of Defibrillation Voltage) Next, the contents of the control performed by the control unit 28 will be explained. Figures 3(A), 3(B), and 3(C) are schematic diagrams illustrating the control performed by the control unit 28. The control unit 28 controls the power supply unit 26 to apply a defibrillation voltage between the catheter electrode 14 and the external electrode 6. For example, as shown in Figure 3(A), the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage between the first electrode group G1 and the second electrode group G2 and the first external electrode 6a. This control may be performed when atrial fibrillation (AF) occurs in patient 2. Also, as shown in Figure 3(B), the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage between the first electrode group G1 and the second electrode group G2 and the second external electrode 6b. This control may be performed when ventricular fibrillation (VF) occurs in patient 2. The control unit 28 can detect whether atrial fibrillation (AF) or ventricular fibrillation (VF) has occurred in patient 2 based on the electrocardiogram waveform acquired from the monitoring device 32.

[0021] By performing defibrillation using catheter electrodes 14 placed inside the heart chamber, it is possible to deliver electrical energy for defibrillation to the affected area more easily compared to external defibrillation, which uses only external electrodes placed on the body surface. Therefore, the success rate of defibrillation can be increased. In addition, the voltage required for defibrillation can be reduced. This makes it possible to avoid risks such as burns to the patient 2. Furthermore, in recent years, 3D mapping systems that obtain three-dimensional anatomical information have come into use. With 3D mapping systems, it was necessary to attach three pairs of patch electrodes to the patient's body surface in the X, Y, and Z axis directions. This can make it difficult to secure space for attaching defibrillation patch electrodes. In contrast, by using catheter electrodes 14 for defibrillation, the number of external electrodes required can be reduced compared to external defibrillation. This makes it easier to perform defibrillation even when a 3D mapping system is being used.

[0022] The control unit 28 may apply a defibrillation voltage between the first external electrode 6a and the catheter electrode 14, and when a predetermined switching condition is met, it may control the power supply unit 26 to switch to applying the defibrillation voltage between the second external electrode 6b and the catheter electrode 14. An example of a switching condition in this control is the occurrence of ventricular fibrillation (VF).

[0023] For example, for atrial fibrillation (AF), cardioversion, or defibrillation, is sometimes performed by applying voltage synchronized with the QRS wave. In cardioversion, voltage may be mistakenly applied near the peak of the T wave, i.e., during the vulnerable phase, resulting in a so-called "Shock on T" state and inducing ventricular fibrillation (VF). Therefore, when the control unit 28 is performing defibrillation for atrial fibrillation (AF) by applying voltage to the first external electrode 6a and catheter electrode 14, and the monitoring device 32 acquires an electrocardiogram waveform indicating the occurrence of ventricular fibrillation (VF), the control unit 28 controls the power supply unit 26 to switch to applying voltage to the second external electrode 6b and catheter electrode 14 to perform defibrillation for ventricular fibrillation (VF).

[0024] Therefore, according to the catheter system 1 of this embodiment, if ventricular fibrillation (VF) occurs during defibrillation for atrial fibrillation (AF), the system can automatically switch to defibrillation for ventricular fibrillation (VF). This allows for faster and more accurate defibrillation for ventricular fibrillation (VF). Furthermore, compared to using an intracardiac electrode catheter for atrial fibrillation (AF) and an external defibrillator for ventricular fibrillation (VF), the effort required to switch from defibrillation for atrial fibrillation (AF) to defibrillation for ventricular fibrillation (VF) can be reduced. In addition, contamination of the surgical field due to the use of an external defibrillator can be avoided.

[0025] Furthermore, the catheter system 1 may be capable of not only switching from defibrillation for atrial fibrillation (AF) to defibrillation for ventricular fibrillation (VF), but also switching from defibrillation for ventricular fibrillation (VF) to defibrillation for atrial fibrillation (AF), or performing defibrillation for both ventricular fibrillation (VF) and atrial fibrillation (AF) simultaneously.

[0026] Furthermore, the control unit 28 may control the power supply unit 26 to apply a defibrillation voltage between the catheter electrodes 14 and between the external electrodes 6. For example, as shown in Figure 3(C), the control unit 28 can control the power supply unit 26 to apply a defibrillation voltage between the first electrode group G1 and the second electrode group G2. The control unit 28 can also control the power supply unit 26 to apply a defibrillation voltage between the first external electrode 6a and the second external electrode 6b. The application of voltage between the catheter electrodes 14 and the application of voltage between the external electrodes 6 may be performed simultaneously, or the system may be controlled so that the application of voltage between the two is not performed when one of the voltage applications is being performed.

[0027] The combination of electrodes to which the defibrillation voltage is applied can be arbitrarily set within the range in which defibrillation can be performed. For example, in addition to the above, such combinations can also include only the first external electrode 6a and the first electrode group G1, only the first external electrode 6a and the second electrode group G2, only the second external electrode 6b and the first electrode group G1, only the second external electrode 6b and the second electrode group G2, only the first external electrode 6a and the second external electrode 6b and the first electrode group G1 and the second electrode group G2, only the first external electrode 6a and the second external electrode 6b and the first electrode group G1, and only the first external electrode 6a and the second external electrode 6b and the second electrode group G2.

[0028] The control unit 28 may control the power supply unit 26 to perform a combination of applying a defibrillation voltage between the catheter electrodes 14 and applying a defibrillation voltage between the catheter electrodes 14 and the external electrode 6. Alternatively, the control unit 28 may control the power supply unit 26 to perform a combination of applying a defibrillation voltage between the external electrodes 6 and applying a defibrillation voltage between the catheter electrodes 14 and the external electrode 6. These measures can help improve the success rate of defibrillation.

[0029] Furthermore, the control unit 28 may apply a defibrillation voltage between the catheter electrode 14 and at least one of the first external electrode 6a and the second external electrode 6b, and when a predetermined switching condition is met, it may control the power supply unit 26 to switch to applying the defibrillation voltage between the first external electrode 6a and the second external electrode 6b. An example of the switching condition in this control is the continuation of atrial fibrillation (AF) for a predetermined period of time.

[0030] For example, when the control unit 28 is performing defibrillation for atrial fibrillation (AF) by applying voltage between the first external electrode 6a and the catheter electrode 14, and the monitoring device 32 acquires an electrocardiogram waveform indicating the occurrence of atrial fibrillation (AF) for a predetermined time from the start of the defibrillation, the control unit 28 controls the power supply unit 26 to switch to applying voltage between the first external electrode 6a and the second external electrode 6b. This can improve the success rate of defibrillation. The "predetermined time" can be set appropriately based on the designer's empirical knowledge or experiments and simulations conducted by the designer, and is set in advance and stored in the control unit 28.

[0031] The switching condition in this control may be the continuation of ventricular fibrillation (VF) for a predetermined period of time. In this case, for example, when the control unit 28 is performing defibrillation for ventricular fibrillation (VF) by applying a voltage between the second external electrode 6b and the catheter electrode 14, and the monitoring device 32 acquires an electrocardiogram waveform indicating the occurrence of ventricular fibrillation (VF) for a predetermined period of time from the start of the defibrillation, the control unit 28 controls the power supply unit 26 to switch to applying a voltage between the first external electrode 6a and the second external electrode 6b.

[0032] Furthermore, the control unit 28 may apply a defibrillation voltage between the catheter electrodes 14, and when predetermined switching conditions are met, it may control the power supply unit 26 to switch to applying the defibrillation voltage between the first external electrode 6a and the second external electrode 6b. For example, when the control unit 28 is performing defibrillation for atrial fibrillation (AF) or ventricular fibrillation (VF) by applying a voltage between the catheter electrodes 14, and the monitoring device 32 acquires an electrocardiogram waveform indicating the occurrence of atrial fibrillation (AF) or ventricular fibrillation (VF) for a predetermined time from the start of the defibrillation, it may control the power supply unit 26 to switch to applying a voltage between the first external electrode 6a and the second external electrode 6b.

[0033] (Application of Ablation Voltage) The control unit 28 may control the power supply unit 26 to apply a voltage for ablation of biological tissue by irreversible electroporation (IRE) between the catheter electrodes 14 and between the catheter electrodes 14 and the external electrode 6. In this disclosure, the defibrillation voltage is, for example, 1V to 2000V, and the ablation voltage is, for example, 1V to 5000V.

[0034] Because IRE is non-thermal, it can minimize damage to surrounding tissues and nerves of the target tissue. For example, when performing pulmonary vein dissection to treat atrial fibrillation (AF), it can suppress damage to the esophagus and phrenic nerve around the affected area, thereby reducing the risk of complications such as esophageal fistula and phrenic nerve paralysis.

[0035] In IRE, pulsed electric field ablation (PFA) is performed. PFA is an ablation procedure that kills cells by using a pulsed electric field generated by applying a high voltage between each catheter electrode 14 and the external electrode 6, or between the catheter electrodes 14 themselves, thereby forming a region (lesion) in the living tissue. The electric field tends to reflect at the boundary between tissues. Therefore, when the affected area is ablated, damage to adjacent tissues can be suppressed. For example, the power supply unit 26 applies a defibrillation voltage and an ablation voltage to each electrode to generate a biphasic pulse (bipolar pulse). Therefore, a positive voltage phase pulse and a negative voltage phase pulse are applied to each electrode, and the polarity of each electrode switches alternately. The power supply unit 26 may also apply a voltage to each electrode to generate a monophasic pulse.

[0036] The control unit 28 can control the power supply unit 26 to apply defibrillation voltage and ablation voltage to each electrode, allowing both catheter ablation, which locally cauterizes the area suspected to be the cause of arrhythmia, and defibrillation to be performed with a single catheter system 1. Therefore, for example, if atrial fibrillation (AF) or ventricular fibrillation (VF) occurs in patient 2 during catheter ablation, defibrillation can be performed quickly.

[0037] The combination of electrodes to which the ablation voltage is applied can be arbitrarily set within the range in which ablation can be performed. For example, the control unit 28 can apply ablation to any combination of the external electrodes 6 shown in Figures 3(A) to 3(C), excluding those between the external electrodes 6. In other words, the control unit 28 can control the power supply unit 26 to apply the ablation voltage between the first electrode group G1 and the second electrode group G2, or between at least one of the first electrode group G1 and the second electrode group G2 and at least one of the first external electrode 6a and the second external electrode 6b, etc. Note that the combination of electrodes used when performing defibrillation and the combination of electrodes used when performing ablation can be mutually applied within the range in which their respective purposes can be achieved.

[0038] The control unit 28 may control the power supply unit 26 to perform a combination of applying an ablation voltage between the catheter electrodes 14 and applying an ablation voltage between the catheter electrodes 14 and the external electrode 6, similar to the case of defibrillation. By applying an ablation voltage between at least one catheter electrode 14 and at least one external electrode 6, monopolar application (also called unipolar application) can be performed. Alternatively, by applying an ablation voltage between the catheter electrodes 14, bipolar application can be performed.

[0039] Monopolar application allows for easier formation of regions deep within tissue compared to bipolar application. Conversely, bipolar application allows for easier formation of regions over a wider area in the direction of tissue surface (i.e., the direction in which the surface expands) compared to monopolar application. Therefore, combining monopolar and bipolar application methods allows for changing the range over which the electric field can be generated. This makes it possible to form regions more reliably over a wider area.

[0040] The order in which monopolar and bipolar voltage applications are performed is not particularly limited. Furthermore, a combination of one monopolar application and one bipolar application may constitute one set, and multiple sets of voltage applications may be performed. Also, the number of monopolar and bipolar applications included in one set is not limited to one each. For example, one set may consist of one or more consecutive monopolar applications and one or more consecutive bipolar applications. Additionally, multiple sets with different contents may be combined in a single ablation procedure.

[0041] In addition, the control unit 28 can control the power supply unit 26 to execute monopolar application alone, or can control the power supply unit 26 to execute bipolar application alone. Whether to execute monopolar application or bipolar application can be selected by the user of the catheter system 1 via the input unit 24. Alternatively, when the control program of the power supply unit 26 is incorporated into the power supply device 8, the control unit 28 may select according to the control program selected by the user via the input unit 24.

[0042] In either monopolar application or bipolar application, the number and combination of the catheter electrodes 14 to which voltage is applied can be appropriately selected. For example, in monopolar application, the catheter electrodes 14 may be sequentially made the voltage application targets one by one. Also, the catheter electrodes 14 may be divided into a plurality of groups, and the voltage application target may be switched in units of groups. Further, voltage may be applied to all of the catheter electrodes 14 simultaneously.

[0043] When voltage is applied to each catheter electrode 14 or each group, the region that can be formed by monopolar application can be enlarged compared to the case where voltage is applied to all of the catheter electrodes 14 simultaneously. This is presumably because when voltage is applied to all of the catheter electrodes 14 that are the voltage application targets at once, the current disperses and flows, so the current density decreases, but when voltage is sequentially applied to each catheter electrode 14 or each group, the current concentrates and the current density increases.

[0044] Also, in bipolar application, the control unit 28 can control the power supply unit 26 to arbitrarily combine a plurality of catheter electrodes 14 and apply voltage between the combined catheter electrodes 14. The combination of the catheter electrodes 14 may be one-to-one, or may be multiple-to-multiple, that is, the groups described above, or may be one-to-multiple.

[0045] In both monopolar and bipolar application methods, when grouping multiple catheter electrodes 14, the method of grouping and the number of groups are not particularly limited. For example, the first electrode group G1 and the second electrode group G2 may each constitute one group, or multiple groups may be formed within the first electrode group G1 and the second electrode group G2, respectively. Furthermore, catheter electrodes 14 belonging to the first electrode group G1 and catheter electrodes 14 belonging to the second electrode group G2 may be assigned to the same group. In addition, there may be a group to which only one catheter electrode 14 belongs, or the same catheter electrode 14 may be assigned to two or more different groups.

[0046] Furthermore, when switching the target of voltage application on an electrode-by-electrode or group-by-group basis, the order of voltage application can be set as appropriate. Also, when switching the target of voltage application on an electrode-by-electrode or group-by-group basis, sequential application may be performed in which the target is switched after one voltage application, or continuous application may be performed in which the target is switched after voltage is applied to the same target multiple times in a row. Sequential application and continuous application may also be combined.

[0047] By continuously applying voltage to the same catheter electrode 14 or group, the number of times the application target is switched can be reduced compared to switching the application target after each voltage application. This simplifies the control performed by the control unit 28. In this disclosure, "applying voltage multiple times consecutively" means applying pulses to the same catheter electrode 14 multiple times without intervening with application to other catheter electrodes 14. The fact that voltage is applied to each catheter electrode 14 multiple times consecutively can be confirmed, for example, by connecting an oscilloscope to each catheter electrode 14. Note that setting the voltage application target on an electrode-by-electrode or group-by-group basis can also be applied to defibrillation.

[0048] (Selection of Electrodes Based on Impedance) The control unit 28 can apply a voltage for impedance measurement between the catheter electrode 14 and the external electrode 6, and select an electrode to be combined with the catheter electrode 14 that is the measurement target of the impedance Z according to the measured impedance Z. The external electrode 6 to which the voltage for impedance measurement is applied is at least one of the first external electrode 6a and the second external electrode 6b.

[0049] In a situation where the tip side of the electrode catheter 4 is disposed within the heart cavity, the targets that the catheter electrode 14 contacts include biological tissue and blood. Also, when physiological saline for perfusion is jetted from the tip of the electrode catheter 4, the physiological saline is also included in the targets that the catheter electrode 14 contacts. Biological tissue has lower conductivity than blood and physiological saline. Therefore, the impedance Z that occurs when a voltage is applied between the catheter electrode 14 and the external electrode 6 becomes relatively high when the catheter electrode 14 is in contact with biological tissue, and becomes relatively low when the catheter electrode 14 is not in contact with biological tissue, that is, when the entire exposed portion of the catheter electrode 14 is in contact with blood or physiological saline. Therefore, it is possible to determine whether or not the catheter electrode 14 is in contact with biological tissue using the impedance Z as an index.

[0050] Therefore, the control unit 28 controls the power supply unit 26 to apply a voltage for impedance measurement between the catheter electrode 14 and the external electrode 6. Then, the control unit 28 acquires information including the voltage value, current value, etc. obtained by the application of the voltage via the power supply unit 26. Thereby, the control unit 28 can measure the impedance Z between the catheter electrode 14 and the external electrode 6. Then, the control unit 28 calculates the difference ΔZ (absolute value) between the measured impedance Z and a predetermined reference impedance Z0, and determines whether the difference ΔZ is greater than or equal to a predetermined threshold value Zth.

[0051] The reference impedance Z0 is the impedance that serves as the reference point, or zero point, when determining contact between the catheter electrode 14 and biological tissue. For example, the reference impedance Z0 can be measured by applying an impedance measurement voltage between the two catheter electrodes 14, provided that the tip of the electrode catheter 4 is positioned within the cardiac chamber and that it is guaranteed that the two catheter electrodes 14 are not in contact with biological tissue. Alternatively, two reference electrodes dedicated to measuring the reference impedance Z0 may be provided on the shaft 10 at a position where it is guaranteed that they will not come into contact with biological tissue, and the reference impedance Z0 may be measured using these two reference electrodes. The reference impedance Z0 is measured in advance within the patient's body and stored in the control unit 28. The threshold value Zth can be set as appropriate based on the designer's empirical knowledge or experiments and simulations conducted by the designer, and is set in advance and stored in the control unit 28.

[0052] When the difference ΔZ is greater than or equal to the threshold Zth, it can be determined that the catheter electrode 14 is in contact with biological tissue. When the catheter electrode 14 is in contact with biological tissue, electrical energy for defibrillation or ablation can be delivered to the biological tissue more reliably than when it is not in contact. Therefore, when the difference ΔZ is greater than or equal to the threshold Zth, the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage or ablation voltage between the catheter electrode 14 used to measure impedance Z and another catheter electrode 14. Furthermore, if the catheter electrode 14 to which the voltage is applied is also confirmed to be in contact with biological tissue by contact determination based on impedance Z, the reliability of defibrillation or ablation can be further enhanced.

[0053] On the other hand, when the difference ΔZ is less than the threshold Zth, it can be determined that the catheter electrode 14 is not in contact with biological tissue. If the catheter electrode 14 is not in contact with biological tissue, a large amount of current flows into the blood or saline solution, making it difficult to transfer electrical energy from the catheter electrode 14 to the biological tissue. Therefore, when the difference ΔZ is less than the threshold Zth, the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage or an ablation voltage between the catheter electrode 14 and the external electrode 6. When the catheter electrode 14 is not in contact with biological tissue, applying the voltage to the external electrode 6 allows for more reliable transfer of electrical energy to the biological tissue compared to applying it to another catheter electrode 14.

[0054] The control unit 28 may control the power supply unit 26 to apply an impedance measurement voltage between the two catheter electrodes 14. In this case, when the difference ΔZ between the impedance Z between the two catheter electrodes 14 and the reference impedance Z0 is greater than or equal to the threshold Zth, it can be determined that both catheter electrodes 14 are in contact with biological tissue. Therefore, the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage or an ablation voltage to the two catheter electrodes 14. On the other hand, when the difference ΔZ is less than the threshold Zth, it can be determined that at least one of the catheter electrodes 14 is not in contact with biological tissue. In this case, for example, the control unit 28 controls the power supply unit 26 to apply a defibrillation voltage or an ablation voltage to either catheter electrode 14, with the external electrode 6 as the target of the voltage application.

[0055] The control unit 28 may inform the user of the catheter system 1 of the fact that the catheter electrode 14 is not in contact with biological tissue by displaying it on the display unit 30, for example. This allows the user to take action such as adjusting the orientation of the shaft 10 so that the catheter electrode 14 makes contact with biological tissue, or instructing the control unit 28 via the input unit 24 to switch the target of the voltage application to another catheter electrode 14.

[0056] Furthermore, the following control may be performed: First, contact with biological tissue is determined for all catheter electrodes 14. Then, if the control unit 28 determines that a catheter electrode 14 to which a defibrillation voltage or ablation voltage is to be applied is not in contact with biological tissue, it may switch to another catheter electrode 14 that is determined to be in contact with biological tissue and perform defibrillation or ablation.

[0057] The control unit 28 may also control the power supply unit 26 to perform defibrillation or ablation by setting the electrode to which the voltage is applied to the electrode selected by the user via the input unit 24 when the difference ΔZ is greater than or equal to the threshold Zth, and to set the electrode to which the voltage is applied to the external electrode 6 when the difference ΔZ is less than the threshold Zth.

[0058] Furthermore, if multiple catheter electrodes 14 are divided into multiple groups and defibrillation voltage or ablation voltage is applied to each group, the contact determination of the catheter electrodes 14 described above may be performed on a group basis. Also, contact determination may be performed periodically during defibrillation or ablation, and the electrode to be used may be switched according to the determination result. In addition, the catheter electrode 14 to which the voltage is applied may be selected or switched according to the number of times and duration the voltage is applied to the catheter electrode 14, the temperature of the catheter electrode 14, etc.

[0059] (Embodiment 2) This embodiment has the same configuration as Embodiment 1, except that there are multiple electrode catheters 4.Hereafter, this embodiment will be described focusing on the configurations that differ from Embodiment 1, and the common configurations will be briefly described or omitted.Figure 4 is a schematic diagram showing how multiple electrode catheters 4 are inserted into the cardiac chambers in the catheter system 1 according to Embodiment 2.

[0060] The catheter system 1 may have a plurality of electrode catheters 4. The electrode catheter 4 in this embodiment includes a first electrode catheter 4a and a second electrode catheter 4b. In the example shown in Figure 4, the first electrode catheter 4a enters the right atrium RA from the superior vena cava (SVC) and extends into the coronary sinus (CS). The second electrode catheter 4b is inserted into the right atrium RA from the inferior vena cava (IVC).

[0061] As an example, the first electrode catheter 4a has the form of a defibrillation catheter, and the second electrode catheter 4b has the form of an ablation catheter. The first electrode catheter 4a has the same structure as the electrode catheter 4 shown in Figure 2, with the first electrode group G1 and the second electrode group G2 provided on the tip side of the shaft 10. The second electrode catheter 4b has a shaft 10, a handle (not shown), and an electrode assembly 36. The shaft 10 of the second electrode catheter 4b has the same structure as the shaft 10 of the first electrode catheter 4a. The handle is provided on the proximal end side of the shaft 10.

[0062] The electrode assembly 36 is provided on the tip side of the shaft 10. As an example, the electrode assembly 36 has a plurality of splines and a plurality of catheter electrodes 14. Each spline is a linear body extending in the axial direction of the shaft 10 and is made of the same flexible material as the shaft 10. The splines are spaced apart from each other in the direction of the axis of the shaft 10. The tip side of each spline is connected to the tip tip. The proximal end of each spline is inserted into the shaft 10 from the tip side and fixed to the shaft 10. The tip side of the inner tube is connected to the tip tip. The inner tube is passed through the lumen of the shaft 10 and its proximal end is connected to the handle. The inner tube can move forward and backward toward the tip and proximal end of the shaft 10 by operating the handle. The plurality of splines can be curved so that they bulge outward as the inner tube is displaced in the axial direction of the shaft 10.

[0063] Multiple catheter electrodes 14 are provided on each spline. The multiple catheter electrodes 14 are arranged at predetermined intervals from each other in the longitudinal direction of each spline. For example, each catheter electrode 14 is ring-shaped and extends around the entire circumference of the spline. Alternatively, the catheter electrode 14 may extend only to a portion of the circumferential direction of the spline. The tip end of a conductor is connected to each catheter electrode 14. The conductor is passed through the inside of the shaft 10, and its proximal end is connected to the connector on the handle. This electrically connects each catheter electrode 14 to the power supply 8 via the conductor. Note that only one catheter electrode 14 may be provided on each spline.

[0064] The control unit 28 may control the power supply unit 26 to perform a combination of voltage application between the catheter electrode 14 on the first electrode catheter 4a and the catheter electrode 14 on the second electrode catheter 4b, voltage application between the catheter electrode 14 on the first electrode catheter 4a and the external electrode 6, and voltage application between the catheter electrode 14 on the second electrode catheter 4b and the external electrode 6. The voltage applied to each electrode may be a voltage for defibrillation or a voltage for ablation.

[0065] In other words, as an example, the catheter system 1 can perform at least one of defibrillation and ablation using the first electrode catheter 4a and the second electrode catheter 4b. Furthermore, it can perform at least one of defibrillation and ablation using the first electrode catheter 4a and at least one of the first external electrode 6a and the second external electrode 6b. Furthermore, it can perform at least one of defibrillation and ablation using the second electrode catheter 4b and at least one of the first external electrode 6a and the second external electrode 6b.

[0066] The second electrode catheter 4b has a shape that makes it easier to bring the catheter electrode 14 into contact with biological tissue than the first electrode catheter 4a. By performing defibrillation with the catheter electrode 14 in contact with biological tissue, the success rate of defibrillation can be increased. In particular, the decrease in the success rate of defibrillation in patient 2 with atrial hypertrophy can be suppressed. Furthermore, by performing ablation with the catheter electrode 14 in contact with biological tissue, region formation can be achieved more reliably.

[0067] When performing defibrillation or ablation using a first electrode catheter 4a and a second electrode catheter 4b, these electrode catheters can be positioned on either side of the target site in the heart. In this disclosure, "positioned on either side" means that the catheter electrodes 14 of each electrode catheter are positioned in a manner that allows the electrical energy necessary for defibrillation or ablation to be applied to the target site. The first electrode catheter 4a and the second electrode catheter 4b only need to be positioned such that the target site is interposed between them, and they do not need to be in physical contact with the target site. For example, one electrode catheter 4 may be inserted through the femoral artery with the catheter electrode 14 placed in the left ventricle, and the other electrode catheter 4 may be inserted through the femoral vein with the catheter electrode 14 placed in the right ventricle, with the two positioned on either side of the target site in the interventricular septum.

[0068] Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed in the right ventricle, and the catheter electrode 14 of the other electrode catheter 4 may be placed in the left ventricle. Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed in the Vein of Marshall (VOM), and the catheter electrode 14 of the other electrode catheter 4 may be placed in the left atrium. Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed on the posterior wall side of the left atrium, and the catheter electrode 14 of the other electrode catheter 4 may be placed in the esophagus. Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed in the coronary sinus CS, and the catheter electrode 14 of the other electrode catheter 4 may be placed on the mitral isthmus side of the left atrium or near the mitral valve. Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed in the pulmonary artery (PA), and the catheter electrode 14 of the other electrode catheter 4 may be placed in the right superior pulmonary vein (RSPV) or on the roof side of the left atrium. Alternatively, the catheter electrode 14 of one electrode catheter 4 may be placed in the aorta, and the catheter electrode 14 of the other electrode catheter 4 may be placed on the posterior wall side of the left atrium.

[0069] The first electrode catheter 4a and the second electrode catheter 4b may both be in the form of a defibrillator catheter, or they may both be in the form of an ablation catheter. The positional relationship between the first electrode catheter 4a and the second electrode catheter 4b may be determined such that the catheter electrodes 14 of one electrode catheter 4 are all positioned in the coronary sinus CS, and the catheter electrodes 14 of the other electrode catheter 4 are all positioned in the right atrium RA.

[0070] In this embodiment as well, the combination of electrodes to which the defibrillation voltage and ablation voltage are applied can be arbitrarily set within a range that allows for defibrillation and ablation. For example, in addition to those described above, such combinations can include the catheter electrodes 14 on the first electrode catheter 4a and the catheter electrodes 14 on the second electrode catheter 4b. Furthermore, if one electrode catheter 4 has a first electrode group G1 and a second electrode group G2, and the other electrode catheter 4 has an electrode assembly 36, a combination of at least one of the first electrode group G1 and the second electrode group G2 and the electrode assembly 36 is also possible. Furthermore, if both electrode catheters 4 have a first electrode group G1 and a second electrode group G2, combinations such as the first electrode group G1 with each other, the second electrode group G2 with each other, or one first electrode group G1 with the other second electrode group G2 are also possible. Furthermore, if both electrode catheters 4 have an electrode assembly 36, a combination of the electrode assemblies 36 with each other is also possible. In addition, the targets for voltage application can be determined on an electrode-by-electrode or group-by-group basis. Furthermore, for defibrillation, a combination of the first external electrode 6a and the second external electrode 6b is also possible.

[0071] (Embodiment 3) This embodiment has the same configuration as Embodiment 1, except that there is one external electrode 6.Hereafter, this embodiment will be described focusing on the configurations that differ from Embodiment 1, and the common configurations will be briefly described or omitted.Figures 5(A) and 5(B) are schematic diagrams illustrating the control performed by the control unit 28 of the catheter system 1 according to Embodiment 3.

[0072] The catheter system 1 may have only one external electrode 6. In this case, the external electrode 6 may be positioned on the patient's body surface in a region where it can perform the functions of both the first external electrode 6a and the second external electrode 6b of Embodiment 1.

[0073] As shown in Figure 5(A), the control unit 28 can control the power supply unit 26 to apply defibrillation voltage and ablation voltage between the first electrode group G1 and the second electrode group G2 and the external electrode 6. Alternatively, the control unit 28 may control the power supply unit 26 to apply voltage only between the external electrode 6 and the first electrode group G1, or only between the external electrode 6 and the second electrode group G2. Furthermore, as shown in Figure 5(B), the control unit 28 can control the power supply unit 26 to apply defibrillation voltage and ablation voltage between the first electrode group G1 and the second electrode group G2. In this embodiment as well, there may be multiple electrode catheters 4, as in Embodiment 2. The combination of electrodes to which defibrillation voltage and ablation voltage are applied can be arbitrarily set within a range in which defibrillation and ablation can be performed.

[0074] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible, as long as they do not deviate from the idea of ​​this disclosure as defined in the claims. A new embodiment with design changes will have the effects of both the combined embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0075] In each embodiment, the configuration of the electrode catheter 4 and the power supply 8 can be changed as appropriate. For example, some of the catheter electrodes 14 may be excluded from the application of the defibrillation voltage or ablation voltage. In this case, the catheter electrodes 14 can be used for potential measurement or as spares when the defibrillation range or ablation range is wide.

[0076] Contact of the electrode with biological tissue can also be determined by using the pressure applied to the catheter electrode 14 as an indicator, in addition to or instead of the impedance Z. When contact determination based on impedance Z and contact determination based on pressure are combined, the control unit 28 may determine that the catheter electrode 14 is in contact with biological tissue only if both determinations determine that the catheter electrode 14 is in contact with biological tissue, or it may determine that the catheter electrode 14 is in contact with biological tissue if contact is determined to be present in either one of the contact determinations, even if the other contact determination determines that there is no contact. There may be three or more electrode catheters 4 and external electrodes 6.

[0077] The control of the power supply unit 26 by the control unit 28 may be implemented by hardware (circuit) or by software (program). If implemented by software, the software consists of a group of programs that cause the computer to execute each function. Each program may be pre-installed in the computer or installed on the computer from a network or recording medium.

[0078] (Response to the earliest abnormal waveform) As described above, the catheter system 1 according to each embodiment can be used in catheter ablation, which locally ablates the area considered to be the cause of the arrhythmia. During ablation, atrial fibrillation (AF), a type of arrhythmia, may occur. If atrial fibrillation (AF) occurs, as described above, electrical energy is supplied via the electrode catheter 4 or external electrode 6 for defibrillation. When atrial fibrillation (AF) is eliminated by the supply of electrical energy, a normal heartbeat often begins, but the site causing the arrhythmia may become abnormally excited before the start of a normal heartbeat.

[0079] The occurrence of this abnormal excitation can be detected by analyzing the electrocardiogram waveform after defibrillation and detecting the earliest abnormal waveform indicating the onset of abnormal excitation. While the majority of these earliest abnormal waveforms are caused by abnormalities in the pulmonary veins, some are caused by abnormalities in other areas. The site of abnormal excitation can be identified from the position of the catheter electrode 14 from which the earliest abnormal waveform was acquired. Therefore, by detecting the earliest abnormal waveform, it becomes possible to effectively perform additional ablation procedures on the site of abnormal excitation.

[0080] The control unit 28 can determine the completion of defibrillation based on, for example, the timing of when the power supply unit 26 is instructed to apply the defibrillation voltage, or the timing of when the instruction is stopped. Furthermore, the earliest abnormal waveform can be detected as follows. That is, for example, the monitoring device 32 uses the catheter electrodes 14 of the electrode catheter 4 as an electrocardiogram measurement unit 34 to acquire the electrocardiogram waveform. In other words, the catheter electrodes 14 for defibrillation are used to acquire the electrocardiogram waveform. All or some of the multiple catheter electrodes 14 of the electrode catheter 4 can function as an electrocardiogram measurement unit 34. The control unit 28 can detect the earliest abnormal waveform based on the electrocardiogram waveform information acquired from the monitoring device 32. Alternatively, the monitoring device 32 may detect the earliest abnormal waveform and transmit a signal to the control unit 28 indicating that the earliest abnormal waveform has been detected.

[0081] The earliest abnormal waveforms are detected, for example, by an abnormality detection unit (not shown) mounted on the control unit 28 or the monitoring device 32. For example, the monitoring device 32 measures electrocardiograms at various locations such as the superior vena cava (SVC), coronary sinus (CS), and right atrial RA using an electrocardiogram measurement unit 34 such as an electrode catheter 4. Furthermore, once a normal heartbeat begins after defibrillation, the first waveform is acquired by the electrocardiogram measurement unit 34, in other words, the catheter electrode 14, which normally measures the electrocardiogram of the right atrium.

[0082] As an example, the abnormality detection unit detects the earliest waveform as the waveform acquired first after the defibrillation waveform corresponding to the application of the defibrillation voltage, and whose amplitude exceeds a predetermined threshold. The threshold is, for example, 0.5 mV. Furthermore, if the earliest waveform is acquired by an electrocardiogram measurement unit 34 different from the electrocardiogram measurement unit 34 that should acquire the waveform first under normal conditions, the abnormality detection unit determines that the earliest waveform is the earliest abnormal waveform.

[0083] Furthermore, the abnormality detection unit can also detect the timing at which the amplitude of the electrocardiogram exceeds a threshold in each of the multiple electrocardiogram measurement units 34, and if the detection order of these timings differs from that of normal operation, it can detect that the earliest abnormal waveform has occurred.

[0084] Furthermore, the anomaly detection unit can also detect the earliest abnormal waveform based on the shape of the earliest waveform. That is, the earliest abnormal waveform detected when abnormal excitation occurs after defibrillation tends to take on a specific shape (hereinafter referred to as the abnormal shape as appropriate). Therefore, the anomaly detection unit can determine that the earliest waveform is the earliest abnormal waveform if its shape matches the abnormal shape.

[0085] When the abnormality detection unit detects the earliest abnormal waveform, the control unit 28 may display the electrocardiogram waveform including the earliest abnormal waveform, as well as information indicating the electrocardiogram measurement unit 34 that detected the earliest abnormal waveform, on the display unit 30. This improves the convenience for the user of the catheter system 1.

[0086] Furthermore, the control unit 28 may transmit an ablation signal instructing the application of a voltage for ablation of biological tissue when the earliest abnormal waveform is included in the electrocardiogram waveform, in other words, when the abnormality detection unit detects the earliest abnormal waveform. For example, the control unit 28 transmits an ablation signal to the power supply unit 26 and controls the power supply unit 26 to apply an ablation voltage to the catheter electrode 14. In other words, the electrode used for defibrillation and acquisition of the electrocardiogram waveform is also used for ablation. The power supply unit 26 applies an ablation voltage to the catheter electrode 14 that has detected the earliest abnormal waveform, as an example. This allows for more reliable treatment of abnormal excitation. The power supply unit 26 may also apply an ablation voltage to another catheter electrode 14, such as a catheter electrode 14 adjacent to the catheter electrode 14 that has detected the earliest abnormal waveform, in addition to or instead of the catheter electrode 14 that has detected the earliest abnormal waveform.

[0087] Furthermore, if the electrode catheter 4 includes a first electrode catheter 4a and a second electrode catheter 4b, the monitoring device 32 may acquire an electrocardiogram waveform using the first electrode catheter 4a. The control unit 28 may also transmit an ablation signal to the power supply unit 26 and control the power supply unit 26 to apply an ablation voltage to the catheter electrode 14 on the second electrode catheter 4b. The control unit 28 can perform ablation by appropriately combining the first electrode catheter 4a, the second electrode catheter 4b, and the external electrode 6.

[0088] If the catheter system 1 includes an ablation device (not shown) in addition to the electrode catheter 4 and power supply 8, the control unit 28 may transmit a signal indicating the detection of the earliest abnormal waveform, or an ablation signal, to the ablation device when the earliest abnormal waveform is detected. Upon receiving the ablation signal, the ablation device applies an ablation voltage to its electrodes. In this case, the electrode catheter 4 and power supply 8 of the catheter system 1 may function solely as defibrillators. Alternatively, electrocardiogram waveform information may be sent from the monitoring device 32 to the ablation device, and the earliest abnormal waveform may be detected in the ablation device. The ablation device can determine the end of defibrillation, for example, by receiving a signal from the control unit 28 indicating the end of defibrillation.

[0089] Furthermore, when detecting the earliest abnormal waveform with the catheter electrode 14 of the first electrode catheter 4a and performing ablation with the catheter electrode 14 of the second electrode catheter 4b or the electrode of another ablation device, for example, the ablation electrode is moved to the vicinity of the waveform detection electrode before the ablation voltage is applied. In this case, the waveform detection electrode and the ablation electrode may come into contact. When the ablation electrode is in contact with the waveform detection electrode, it is difficult to perform accurate ablation.

[0090] When such contact occurs, noise appears in the electrocardiogram waveform detected by the waveform detection electrode. The control unit 28 may then notify the user of the occurrence of the noise by displaying it on the display unit 30. This allows the user to take measures such as shifting the relative positions of the waveform detection electrode and the ablation electrode to prevent contact. Alternatively, the control unit 28 and the ablation device may start ablation when they detect that the contact has been resolved and that it is possible to apply the ablation voltage, or they may prompt the user to start ablation by displaying on the display unit 30 that it is possible to apply the ablation voltage.

[0091] Furthermore, in the control system that detects the earliest abnormal waveform after defibrillation and performs ablation, defibrillation is not limited to being performed by a combination of catheter electrodes 14 and external electrodes 6. For example, defibrillation may be performed by applying a defibrillation voltage between the catheter electrodes 14, followed by detection of the earliest abnormal waveform and ablation.

[0092] Embodiments may be specified by the following items: [Item 1] A catheter system (1) comprising: an electrode catheter (4) having a catheter electrode (14) at its tip and inserted into the heart chamber; an external electrode (6) positioned on the body surface; a power supply unit (26) electrically connected to the catheter electrode (14) and the external electrode (6) and applying voltage to the catheter electrode (14) and the external electrode (6); and a control unit (28) that controls the power supply unit (26) to apply a defibrillation voltage between the catheter electrode (14) and the external electrode (6). [Item 2] The catheter system (1) of Item 1, wherein the electrode catheter (4) has a plurality of catheter electrodes (14), and the control unit (28) controls the power supply unit (26) to perform voltage application between the catheter electrodes (14) and voltage application between the catheter electrodes (14) and the external electrode (6). [Item 3] The catheter system (1) according to item 1 or item 2, wherein the electrode catheter (4) includes a first electrode catheter (4a) and a second electrode catheter (4b), and the control unit (28) controls the power supply unit (26) to perform the following: applying a voltage between the catheter electrode (14) on the first electrode catheter (4a) and the catheter electrode (14) on the second electrode catheter (4b), applying a voltage between the catheter electrode (14) on the first electrode catheter (4a) and an external electrode (6), and applying a voltage between the catheter electrode (14) on the second electrode catheter (4b) and an external electrode (6). [Item 4] The catheter system (1) according to any of Items 1 to 3, wherein the external electrode (6) includes a first external electrode (6a) and a second external electrode (6b), and the control unit (28) applies a voltage between the first external electrode (6a) and the catheter electrode (14), and when a predetermined switching condition is met, controls the power supply unit (26) to switch to applying a voltage between the second external electrode (6b) and the catheter electrode (14).[Item 5] A catheter system (1) according to any of Items 1 to 4, wherein the external electrode (6) includes a first external electrode (6a) and a second external electrode (6b), and the control unit (28) applies a voltage between the catheter electrode (14) and at least one of the first external electrode (6a) and the second external electrode (6b), and when a predetermined switching condition is met, controls the power supply unit (26) to switch to applying a voltage between the first external electrode (6a) and the second external electrode (6b). [Item 6] An electrode catheter (4) having a plurality of catheter electrodes (14), an external electrode (6) including a first external electrode (6a) and a second external electrode (6b), and a control unit (28) performing voltage application between the catheter electrodes (14), and when predetermined switching conditions are met, controlling the power supply unit (26) to switch to applying voltage between the first external electrode (6a) and the second external electrode (6b), a catheter system (1) according to any of items 1 to 5. [Item 7] A catheter system (1) according to any of Items 1 to 6, wherein the electrode catheter (4) has a plurality of catheter electrodes (14), and the control unit (28) measures impedance (Z) by applying a voltage for impedance measurement between the catheter electrodes (14) and the external electrode (6), or between the catheter electrodes (14) themselves, and when the difference (ΔZ) between the measured impedance (Z) and a reference impedance (Z0), which is a reference point for determining contact between the catheter electrodes (14) and biological tissue, is greater than or equal to a predetermined threshold (Zth), the power supply unit (26) is controlled to apply a voltage between the catheter electrodes (14) themselves, and when the difference (ΔZ) is less than the threshold (Zth), the power supply unit (26) is controlled to apply a voltage between the catheter electrodes (14) and the external electrode (6). [Item 8] A catheter system (1) according to any of Items 1 to 7, wherein the electrode catheter (4) has a plurality of catheter electrodes (14), and the control unit (28) controls the power supply unit (26) to apply a voltage for ablation of biological tissue by irreversible electroporation between the catheter electrodes (14) and between the catheter electrodes (14) and the external electrode (6).[Item 9] A catheter system (1) according to any of Items 1 to 8, wherein the catheter electrode (14) acquires an electrocardiogram waveform, and the control unit (28) transmits an ablation signal instructing the application of a voltage for ablation of biological tissue by irreversible electroporation when the electrocardiogram waveform contains the earliest abnormal waveform. [Item 10] A catheter system (1) according to Item 9, wherein the control unit (28) transmits an ablation signal to the power supply unit (26) and controls the power supply unit (26) to apply an ablation voltage to the catheter electrode (14). [Item 11] The catheter system (1) of Item 9, wherein the electrode catheter (4) includes a first electrode catheter (4a) and a second electrode catheter (4b), the catheter electrode (14) on the first electrode catheter (4a) acquires an electrocardiogram waveform, the control unit (28) transmits an ablation signal to the power supply unit (26) and controls the power supply unit (26) to apply an ablation voltage to the catheter electrode (14) on the second electrode catheter (4b). [Item 12] The catheter system (1) comprises a power supply unit (8) including a power supply unit (26) and a control unit (28), and an ablation device separate from the power supply unit (8), the control unit (28) transmits an ablation signal to the ablation device, the ablation device has electrodes separate from the electrode catheter (4) and external electrodes (6) and applies an ablation voltage to the electrodes.

[0093] This disclosure relates to a catheter system.

[0094] 1 Catheter system, 4 Electrode catheters, 4a First electrode catheter, 4b Second electrode catheter, 6 External electrodes, 6a First external electrode, 6b Second external electrode, 14 Catheter electrodes, 26 Power supply unit, 28 Control unit.

Claims

1. A catheter system comprising: an electrode catheter having a catheter electrode at its tip and inserted into the cardiac chamber; an external electrode placed on the body surface; a power supply unit electrically connected to the catheter electrode and the external electrode and applying voltage to the catheter electrode and the external electrode; and a control unit that controls the power supply unit to apply a defibrillation voltage between the catheter electrode and the external electrode.

2. The catheter system according to claim 1, wherein the electrode catheter has a plurality of catheter electrodes, and the control unit controls the power supply unit to perform voltage application between the catheter electrodes and voltage application between the catheter electrodes and the external electrode.

3. The catheter system according to claim 1 or 2, wherein the electrode catheter includes a first electrode catheter and a second electrode catheter, and the control unit controls the power supply unit to perform the following: applying a voltage between the catheter electrode on the first electrode catheter and the catheter electrode on the second electrode catheter, applying a voltage between the catheter electrode on the first electrode catheter and the external electrode, and applying a voltage between the catheter electrode on the second electrode catheter and the external electrode.

4. The catheter system according to claim 1 or 2, wherein the external electrode includes a first external electrode and a second external electrode, and the control unit performs voltage application between the first external electrode and the catheter electrode, and when a predetermined switching condition is met, controls the power supply unit to switch to voltage application between the second external electrode and the catheter electrode.

5. The catheter system according to claim 1 or 2, wherein the external electrode includes a first external electrode and a second external electrode, and the control unit performs voltage application between the catheter electrode and at least one of the first external electrode and the second external electrode, and controls the power supply unit to switch to voltage application between the first external electrode and the second external electrode when a predetermined switching condition is met.

6. The catheter system according to claim 1 or 2, wherein the electrode catheter has a plurality of catheter electrodes, the external electrode includes a first external electrode and a second external electrode, and the control unit applies a voltage between the catheter electrodes and controls the power supply unit to switch to applying a voltage between the first external electrode and the second external electrode when predetermined switching conditions are met.

7. The catheter system according to claim 1 or 2, wherein the electrode catheter has a plurality of catheter electrodes, the control unit measures impedance by applying a voltage for impedance measurement between the catheter electrodes and the external electrodes, or between the catheter electrodes themselves, and controls the power supply unit to apply a voltage between the catheter electrodes themselves when the difference between the measured impedance and a reference impedance which is a reference point for determining contact of the catheter electrodes with biological tissue is greater than or equal to a predetermined threshold, and to apply a voltage between the catheter electrodes and the external electrodes when the difference is less than the threshold.

8. The catheter system according to claim 1 or 2, wherein the electrode catheter has a plurality of catheter electrodes, and the control unit controls the power supply to apply a voltage for ablation of biological tissue by irreversible electroporation between the catheter electrodes and between the catheter electrodes and the external electrode.

9. The catheter system according to claim 1 or 2, wherein the catheter electrode acquires an electrocardiogram waveform, and the control unit transmits an ablation signal instructing the application of a voltage for ablation of biological tissue by irreversible electroporation when the electrocardiogram waveform contains the earliest abnormal waveform.

10. The catheter system according to claim 9, wherein the control unit transmits the ablation signal to the power supply unit and controls the power supply unit to apply an ablation voltage to the catheter electrode.

11. The catheter system according to claim 9, wherein the electrode catheter includes a first electrode catheter and a second electrode catheter, the catheter electrode on the first electrode catheter acquires the electrocardiogram waveform, the control unit transmits the ablation signal to the power supply unit and controls the power supply unit to apply an ablation voltage to the catheter electrode on the second electrode catheter.

12. The catheter system according to claim 9, comprising a power supply unit including the power supply unit and the control unit, and an ablation device separate from the power supply unit, wherein the control unit transmits the ablation signal to the ablation device, and the ablation device has an electrode separate from the electrode catheter and the external electrode, and applies an ablation voltage to the electrode.

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