Ablation system

The ablation system employs irreversible electroporation with monopolar and bipolar voltage applications to address thermal damage issues in RF ablation, achieving targeted tissue lesions with reduced collateral damage.

WO2026120894A1PCT designated stage Publication Date: 2026-06-11JAPAN LIFELINE CO LTD
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
JAPAN LIFELINE CO LTD
Filing Date
2025-09-25
Publication Date
2026-06-11

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Abstract

An ablation system 1 for performing ablation of biological tissue 2 using an irreversible electroporation method comprises: a surgical treatment tool 4 having a shaft 10, a clip part 12 including a pair of holding pieces 16 and at least one ablation electrode provided on at least one of the holding pieces 16, and an operation part 22 that opens and closes the clip part 12; a counter electrode plate 6; a power supply part 26 that applies a voltage to the at least one ablation electrode 18 and the counter electrode plate 6; and a control part 28 that controls the power supply part 26 so as to execute monopolar system application that applies the voltage between the at least one ablation electrode 18 and the counter electrode plate 6.
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Description

Ablation system 【0001】 The present disclosure relates to an ablation system. 【0002】 Patent Document 1 discloses a surgical device used for ablation performed in cardiac surgery. This surgical device has a clip portion and ablates living tissue using radio frequency (RF) energy. 【0003】 Japanese Patent Translation of PCT International Publication No. 2022-525823 【0004】 As a result of intensive studies by the present inventor, a new ablation technique was conceived in which living tissue is ablated using energy other than RF energy with a surgical device having a clip portion. 【0005】 The present disclosure has been made in view of such circumstances, and an object thereof is to provide a novel technique related to ablation. 【0006】 One aspect of the present disclosure is an ablation system for performing ablation of living tissue using irreversible electroporation. This ablation system includes a shaft, a clip portion provided on the tip side of the shaft and including a pair of clamping pieces and at least one ablation electrode provided on at least one of the clamping pieces, and a surgical treatment instrument provided on the proximal side of the shaft and having an operation portion for opening and closing the clip portion, a counter electrode plate, a power supply portion for applying a voltage to at least one ablation electrode and the counter electrode plate, and a control portion for controlling the power supply portion so as to execute monopolar application for applying a voltage between at least one ablation electrode and the counter electrode plate. 【0007】 Any combination of the above components, and those obtained by converting the expressions 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 ablation can be provided. 【0009】These are schematic diagrams of an ablation system according to an embodiment. Figures 2(A), 2(B), and 2(C) are perspective views of the clip portion. Figures 3(A), 3(B), and 3(C) are schematic diagrams illustrating monopolar application using the clip portion in the open state. Figures 4(A), 4(B), and 4(C) are schematic diagrams illustrating bipolar application performed when the clip portion is in the open state and not clamping biological tissue. Figures 4(D), 4(E), and 4(F) are schematic diagrams illustrating bipolar application performed when the clip portion is clamping biological tissue. These are schematic diagrams illustrating a combination of monopolar application and bipolar application using the clip portion in the open state. Figures 6(A), 6(B), and 6(C) are schematic diagrams illustrating monopolar application using the clip portion in the closed state. Figures 7(A), 7(B), and 7(C) are schematic diagrams illustrating bipolar application using the clip portion in the closed state. This is a schematic diagram illustrating the combination of monopolar and bipolar application methods using a clip in a closed state. 【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】Figure 1 is a schematic diagram of an ablation system 1 according to an embodiment. In Figure 1, some of the components of the ablation system 1 are depicted as functional blocks. At least some of these functional blocks can be implemented as hardware components and circuits, including the CPU and memory of a computer, and as software components, such as computer programs. It will be understood by those skilled in the art that these functional blocks can be implemented in various ways through combinations of hardware and software. 【0012】 The ablation system 1 performs ablation on the patient's biological tissue 2. In this embodiment, the biological tissue 2 to be ablated is the heart, which is experiencing arrhythmia. The ablation system 1 can also be used for surgical treatments such as ablation for cancers occurring in organs such as the digestive tract (including the bile duct) and the respiratory system (including the lungs), as well as nerve ablation for pain relief. The ablation system 1 comprises a surgical instrument 4, a counter electrode plate 6, and a power supply device 8. 【0013】 The surgical instrument 4 comprises a shaft 10, a clip portion 12, and a handle 14. The shaft 10 is, for example, a tubular body that is long in one direction, with at least its tip positioned inside the patient's body. The shaft 10 is made of known flexible materials including resins such as nylon, nylon elastomer, polytetrafluoroethylene, polyethylene, vinyl chloride, polyolefin, polytetrafluoroethylene, polyether block amide, and polyamide, or known metallic materials including pseudoelastic alloys such as Ni-Ti alloys, superelastic alloys, shape memory alloys, stainless steel, aluminum, aluminum alloys, copper, and copper alloys. The shaft 10 has, for example, a double-tube structure, through which various thin wires (not shown), such as conductors, are inserted. The inner tube is also slidable relative to the outer tube in the axial direction of the shaft 10. 【0014】A clip portion 12 is provided at the tip of the shaft 10. Figures 2(A), 2(B), and 2(C) are perspective views of the clip portion 12. The clip portion 12 has a pair of clamping pieces 16 and a plurality of ablation electrodes 18. The clamping pieces 16 are also called clip pieces or forceps pieces. Each clamping piece 16 is a tubular body that is long in one direction and protrudes from the circumferential surface of the shaft 10 in a direction intersecting the axial direction of the shaft 10. The shape of each clamping piece 16 is not particularly limited and may be circular or rectangular. In other words, the shape of the cross-section intersecting the extending direction of the clamping piece 16 may be circular or polygonal. The shape of the cross-section may also be semicircular, etc. Furthermore, each clamping piece 16 may protrude linearly or curved from the circumferential surface of the shaft 10. Furthermore, the angle between each clamping piece 16 and the shaft 10 is not particularly limited; the angle may be a right angle, an acute angle, or an obtuse angle. Each clamping piece 16 is made of a high-rigidity material, similar to the shaft 10. 【0015】 The clip portion 12 can be opened and closed by operating the operation portion 22, which will be described later. The closed state of the clip portion 12 is when the pair of clamping pieces 16 are in contact with each other. The open state of the clip portion 12 is when the pair of clamping pieces 16 are separated from each other. Figure 2(A) shows the clip portion 12 in a fully open state. Figure 2(B) shows the clip portion 12 in a partially open state. Figure 2(C) shows the clip portion 12 in a closed state. In this disclosure, the "closed state of the clip portion 12" also includes a state in which the pair of clamping pieces 16 are separated from each other and the gap between the pair of clamping pieces 16 is less than or equal to a predetermined size. This predetermined size is, for example, the dimension in the direction in which the pair of clamping pieces 16 are aligned at the widest part of each clamping piece 16, in other words, at the part where the area of ​​the cross-section perpendicular to the extending direction of the clamping piece 16 is maximum. 【0016】For example, one clamping piece 16 is fixed to the tip of the outer tube of the shaft 10. A slit (not shown) extending in the axial direction of the shaft 10 is provided on the circumferential surface of the outer tube at a position that overlaps with the first clamping piece 16 in the circumferential direction of the shaft 10. The tip of the inner tube is exposed to the outside through the slit. The other clamping piece 16 is fixed to this exposed portion. Hereinafter, the clamping piece 16 fixed to the outer tube will be referred to as the first clamping piece 16a, and the clamping piece 16 fixed to the inner tube will be referred to as the second clamping piece 16b. Also, when there is no need to distinguish between the first clamping piece 16a and the second clamping piece 16b, they may simply be referred to as "clamping piece 16". 【0017】 The first clamping piece 16a is positioned closer to the tip of the shaft 10 than the second clamping piece 16b. The positions of the first clamping piece 16a and the second clamping piece 16b in the circumferential direction of the shaft 10 overlap. When the operating part 22 is operated, the inner tube slides relative to the outer tube in the axial direction of the shaft 10. Consequently, the second clamping piece 16b slides in the axial direction of the shaft 10 within the slit. This allows the second clamping piece 16b to move closer to or further away from the first clamping piece 16a. This displacement of the second clamping piece 16b causes the clip portion 12 to switch from an open state to a closed state, or from a closed state to an open state. 【0018】Multiple ablation electrodes 18 are provided on a pair of clamping pieces 16. In this embodiment, multiple ablation electrodes 18 are provided on each of the first clamping piece 16a and the second clamping piece 16b. On each clamping piece 16, the multiple ablation electrodes 18 are arranged at predetermined intervals from each other in the longitudinal direction of the clamping piece 16. The surgical instrument 4 of this embodiment, as an example, has a first ablation electrode 18a, a second ablation electrode 18b, a third ablation electrode 18c, and a fourth ablation electrode 18d on each clamping piece 16, but the number of ablation electrodes 18 provided on each clamping piece 16 is not limited to four. For example, one ablation electrode 18 may be provided on each clamping piece 16. Also, multiple ablation electrodes 18 may be provided on only one of the two clamping pieces 16, and the other may not have any ablation electrodes 18. Furthermore, one ablation electrode 18 may be provided on only one of the two clamping pieces 16, while the other does not have an ablation electrode 18. In this disclosure, when it is not necessary to distinguish between the first ablation electrode 18a to the fourth ablation electrode 18d, they may simply be referred to as "ablation electrode 18". 【0019】 Each ablation electrode 18 is made of a highly conductive metal such as platinum, gold, silver, copper, aluminum, or stainless steel, or an alloy thereof. Preferably, each ablation electrode 18 is ring-shaped and extends around the entire circumference of the clamping piece 16. This expands the range of positional possibilities for the clamping piece 16 that allows the ablation electrode 18 to contact the biological tissue 2. Performing ablation with the ablation electrode 18 in contact with the biological tissue 2 allows for more reliable formation of a region (lesion) in the biological tissue 2. Therefore, making the ablation electrode 18 ring-shaped increases the freedom of positioning and positioning of the surgical instrument 4 during ablation. Alternatively, the ablation electrode 18 may extend only to a portion of the circumferential direction of the clamping piece 16. 【0020】The tip end of a conductor (not shown) is connected to each ablation electrode 18. The conductor is passed through the inside of the clamping piece 16 and the shaft 10, and its base end is connected to a connector (not shown) on the handle 14 shown in Figure 1. The power supply 8 is electrically connected to each conductor via the connector on the handle 14. Therefore, each ablation electrode 18 is electrically connected to the power supply 8 via the conductor and connector. As will be described in detail later, the power supply 8 supplies power for ablation to the multiple ablation electrodes 18. 【0021】 Returning to Figure 1, the handle 14 is provided on the base end of the shaft 10 and is positioned outside the body when the surgical instrument 4 is in use, and is grasped and operated by the user. The handle 14 has a main body portion 20 that is grasped by the user and an operating portion 22 for opening and closing the clip portion 12. By operating the operating portion 22, the second clamping piece 16b can be moved forward and backward relative to the first clamping piece 16a. This makes it possible to switch between the open and closed states of the clip portion 12. The connector is provided on the main body portion 20. Furthermore, by adjusting the amount of operation of the operating portion 22, the degree of separation between the first clamping piece 16a and the second clamping piece 16b, in other words, the degree to which the clip portion 12 is open can be changed in multiple stages or continuously. The surgical instrument 4 may also have an irrigation mechanism that sprays an irrigation fluid such as physiological saline from the tip side during ablation. 【0022】 The counter electrode plate 6 is attached to the patient's body surface during ablation. The counter electrode plate 6 is also electrically connected to the power supply unit 8. As will be described in detail later, the power supply unit 8 supplies power for ablation to the counter electrode plate 6. 【0023】 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 ablation 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. 【0024】 The power supply unit 26 is electrically connected to the surgical instrument 4 and the counter electrode plate 6. The power supply unit 26 supplies the ablation voltage V to the multiple ablation electrodes 18 and the counter electrode plate 6 according to the control signal CTL sent from the control unit 28. ｏｕｔを A voltage can be applied. 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 Vout to each ablation electrode 18 and counter electrode plate 6 by sending a control signal CTL 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. 【0025】 Next, the control performed by the control unit 28 will be described. The ablation system 1 of this embodiment performs ablation on biological tissue 2 using irreversible electroporation (IRE). Since IRE is non-thermal, it can suppress damage to tissues and nerves located around the biological tissue 2 being treated. For example, when performing pulmonary vein dissection to treat atrial fibrillation, it is possible to suppress damage to the esophagus and phrenic nerve around the affected area, thereby suppressing the occurrence of complications such as esophageal fistula and phrenic nerve paralysis. 【0026】 In IRE, pulsed electric field ablation (PFA) is performed. Therefore, according to this embodiment, a novel ablation technique using PFA instead of RF can be provided. PFA is an ablation technique that kills cells by a pulsed electric field generated by applying a high voltage between each ablation electrode 18 and the counter electrode plate 6, or between the ablation electrodes 18 themselves, thereby forming a region in the biological tissue 2. The electric field tends to reflect at the boundary between tissues. For this reason, damage to adjacent tissues can be suppressed when the affected area is cauterized. 【0027】In this embodiment, the power supply unit 26 applies voltage to each ablation electrode 18 and counter electrode plate 6 to generate biphase pulses (bipolar pulses). Therefore, positive voltage phase pulses and negative voltage phase pulses are applied to each ablation electrode 18 and counter electrode plate 6, and the polarity of each ablation electrode 18 and counter electrode plate 6 alternately switches. The voltage amplitude value Am is, for example, 1000V to 4000V. The pulse width Δp is, for example, 0.1μs to 100μs. 【0028】 With the clip portion 12 positioned inside the patient's body and in contact with the biological tissue 2 representing the affected area, the control unit 28 controls the power supply unit 26 to apply voltage to each ablation electrode 18 and counter electrode plate 6. Specifically, the control unit 28 controls the power supply unit 26 to perform monopolar application (also called unipolar application). In addition, the control unit 28 in this embodiment can control the power supply unit 26 to perform a combination of bipolar and monopolar application. The control unit 28 can also control the power supply unit 26 to perform monopolar application alone, or to perform bipolar application alone. Whether to perform monopolar or bipolar application may be selected by the user of the ablation system 1 via the input unit 24, or, if the control program for 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. In other words, the user can input a signal to the control unit 28 via the input unit 24 that indicates which method of application to perform. 【0029】 In monopolar application, a voltage is applied between at least one ablation electrode 18 and the counter electrode plate 6. In bipolar application, a voltage is applied between the ablation electrodes 18. Therefore, monopolar application makes it easier to form regions deep into the biological tissue 2 than bipolar application. On the other hand, bipolar application makes it easier to form regions over a wide area in the direction of the surface of the biological tissue 2 (i.e., the direction in which the surface expands) than monopolar application. 【0030】 Furthermore, the control unit 28 controls the power supply unit 26 to apply voltage to the ablation electrode 18 at least when the clip portion 12 is in the closed state. In this embodiment, the control unit 28 can control the power supply unit 26 to apply voltage to the ablation electrode 18 both when the clip portion 12 is in the closed state and when it is in the open state. In other words, the ablation system 1 of this embodiment can perform both monopolar and bipolar voltage application both when the clip portion 12 is in the closed state and when it is in the open state. 【0031】 (Monopolar application using the clip portion 12 in the open state) Figures 3(A), 3(B), and 3(C) are schematic diagrams illustrating monopolar application using the clip portion 12 in the open state. For example, as shown in Figure 3(A), the control unit 28 can control the power supply unit 26 to apply voltage between the ablation electrode 18 and the counter electrode plate 6, by sequentially applying voltage to each ablation electrode 18 on each clamping piece 16 of the clip portion 12 in the open state. 【0032】 As an example, the voltage is first applied to the first ablation electrode 18a, second ablation electrode 18b, third ablation electrode 18c, and fourth ablation electrode 18d of the first clamping piece 16a in that order, and a voltage is applied between each ablation electrode 18 and the counter electrode plate 6. In other words, a voltage is applied between the first ablation electrode 18a of the first clamping piece 16a and the counter electrode plate 6, then between the second ablation electrode 18b of the first clamping piece 16a and the counter electrode plate 6, then between the third ablation electrode 18c of the first clamping piece 16a and the counter electrode plate 6, and then between the fourth ablation electrode 18d of the first clamping piece 16a and the counter electrode plate 6. Next, the voltage is applied to the first ablation electrode 18a, second ablation electrode 18b, third ablation electrode 18c, and fourth ablation electrode 18d of the second clamping piece 16b in that order, and a voltage is applied between each ablation electrode 18 and the counter electrode plate 6. 【0033】Furthermore, the control unit 28 can divide the multiple ablation electrodes 18 into multiple groups and switch the target of voltage application on a group basis to perform monopolar application. For example, as shown in Figure 3(B), the first ablation electrodes 18a to the fourth ablation electrodes 18d on the first clamping piece 16a are designated as the first group, and the first ablation electrodes 18a to the fourth ablation electrodes 18d on the second clamping piece 16b are designated as the second group. Then, after a voltage is applied between the four ablation electrodes 18 belonging to the first group and the counter electrode plate 6, a voltage is applied between the four ablation electrodes 18 belonging to the second group and the counter electrode plate 6. In other words, a voltage is applied simultaneously to the first ablation electrodes 18a to the fourth ablation electrodes 18d on each clamping piece 16. "Simultaneous application" in this disclosure means that the state in which a voltage is applied to each ablation electrode 18 overlaps at least for a certain period of time. 【0034】 Furthermore, as shown in Figure 3(C), the control unit 28 can also control the power supply unit 26 to apply voltage between all ablation electrodes 18 and the counter electrode plate 6, treating all ablation electrodes 18 of the clip unit 12 as targets for simultaneous voltage application. However, when applying voltage to each ablation electrode 18 or each group, the region that can be formed by monopolar application can be made larger compared to when voltage is applied simultaneously to all ablation electrodes 18 of the clip unit 12. This is thought to be because when voltage is applied to all ablation electrodes 18 at once, the current is dispersed and flows, reducing the current density, but when voltage is applied sequentially to each ablation electrode 18 or each group, the current is concentrated and the current density increases. 【0035】When grouping multiple ablation electrodes 18, the method of grouping and the number of groups are not particularly limited. For example, there may be a group to which only one ablation electrode 18 belongs, or the same ablation electrode 18 may be assigned to two or more different groups. Also, the ablation electrode 18 on the first clamping piece 16a and the ablation electrode 18 on the second clamping piece 16b may be assigned to the same group. 【0036】 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. Furthermore, when switching the target of voltage application on an electrode-by-electrode or group-by-group basis, the application target may be switched after a single voltage application (hereinafter referred to as sequential application), or the application target may be switched after voltage has been applied to the same target multiple times consecutively (hereinafter referred to as continuous application). Sequential and continuous application may also be combined. 【0037】 By continuously applying voltage to the same ablation electrode 18 or group, the number of times the application target is switched can be reduced compared to switching the application target each time voltage is applied. This simplifies the control performed by the control unit 28. In this disclosure, "applying voltage multiple times consecutively" means applying a biphasic pulse to the same ablation electrode 18 multiple times without applying it to other ablation electrodes 18 in between. The fact that voltage has been applied to each ablation electrode 18 multiple times consecutively can be confirmed, for example, by connecting an oscilloscope to each ablation electrode 18. 【0038】(Bipolar application using the clip portion 12 in the open state) Figures 4(A), 4(B), and 4(C) are schematic diagrams illustrating bipolar application performed when the clip portion 12 is in the open state and not clamping biological tissue 2. Figures 4(D), 4(E), and 4(F) are schematic diagrams illustrating bipolar application performed when the clip portion 12 is clamping biological tissue 2. The control unit 28 can arbitrarily combine a plurality of ablation electrodes 18 on the open clip portion 12 and control the power supply unit 26 to apply a voltage between the combined ablation electrodes 18. The control unit 28 can also perform bipolar application in both the state where biological tissue 2 is clamped between the pair of clamping pieces 16 and the state where it is not clamped. The monopolar application described above can also be performed in both the state where biological tissue 2 is clamped between the pair of clamping pieces 16 and the state where it is not clamped. Examples of biological tissue 2 that can be grasped by a pair of clamping pieces 16 include the pulmonary veins and the left atrial appendage. 【0039】 For example, as shown in Figures 4(A) and 4(D), the control unit 28 controls the power supply unit 26 to combine two ablation electrodes 18 provided on the same clamping piece 16 and apply a voltage between the two ablation electrodes 18. As an example, first a voltage is applied between the first ablation electrode 18a and the second ablation electrode 18b of the first clamping piece 16a, then a voltage is applied between the second ablation electrode 18b and the third ablation electrode 18c of the first clamping piece 16a, and then a voltage is applied between the third ablation electrode 18c and the fourth ablation electrode 18d of the first clamping piece 16a. Next, a voltage is applied between the first ablation electrode 18a and the second ablation electrode 18b of the second clamping piece 16b, then a voltage is applied between the second ablation electrode 18b and the third ablation electrode 18c of the second clamping piece 16b, and then a voltage is applied between the third ablation electrode 18c and the fourth ablation electrode 18d of the second clamping piece 16b. 【0040】Furthermore, as shown in Figures 4(B) and 4(E), the control unit 28 can combine the ablation electrode 18 on the first clamping piece 16a and the ablation electrode 18 on the second clamping piece 16b and control the power supply unit 26 to apply a voltage between the two ablation electrodes 18. For example, first, a voltage is applied between the first ablation electrodes 18a of the first clamping piece 16a and the second clamping piece 16b, then a voltage is applied between the second ablation electrodes 18b of the first clamping piece 16a and the second clamping piece 16b, then a voltage is applied between the third ablation electrodes 18c of the first clamping piece 16a and the second clamping piece 16b, and then a voltage is applied between the fourth ablation electrodes 18d of the first clamping piece 16a and the second clamping piece 16b. 【0041】 Furthermore, as shown in Figures 4(C) and 4(F), the control unit 28 can also perform a combination of bipolar voltage application, where two ablation electrodes 18 provided on the same clamping piece 16 are the targets of voltage application, and bipolar voltage application, where two ablation electrodes 18 provided on different clamping pieces 16 are the targets of voltage application. 【0042】 Instead of clamping the biological tissue 2 with the clip portion 12, ablation can also be performed by pressing the open clip portion 12 against the surface of the biological tissue 2. This allows for the formation of regions over a wide area of ​​the surface of the biological tissue 2. Therefore, the time required for ablation can be shortened when performing ablation on the surface of the biological tissue 2. 【0043】When applying a voltage between the ablation electrode 18 on the first clamping piece 16a and the ablation electrode 18 on the second clamping piece 16b with the biological tissue 2 sandwiched by the clip part 12, the first clamping piece 16a and the second clamping piece 16b are closer to each other than in the fully open state. For this reason, a combination may occur where the combined ablation electrodes 18 are overly close to each other. If the two ablation electrodes 18 are overly close, it is conceivable that a large current may flow between the two ablation electrodes 18 and spark discharge may occur. Therefore, when performing bipolar mode application with the biological tissue 2 sandwiched by the pair of clamping pieces 16, the control unit 28 calculates the distance between the ablation electrodes 18 from the operation amount of the operation unit 22 or the like, and according to the calculation result, control such as avoiding the execution of bipolar mode application or switching the ablation electrode 18 to which the voltage is applied may be performed. 【0044】 The order of voltage application to each combination of the ablation electrodes 18 can be set as appropriate. Also, the combination method of the ablation electrodes 18 to which the voltage is applied can be set as appropriate. For example, non-adjacent ablation electrodes 18 on each clamping piece 16 may be combined. As an example, on each clamping piece 16, the first ablation electrode 18a and the third ablation electrode 18c may be combined, and the second ablation electrode 18b and the fourth ablation electrode 18d may be combined. Also, on each clamping piece 16, the first ablation electrode 18a and the second ablation electrode 18b may be combined, and the first ablation electrode 18a and the third ablation electrode 18c may be combined. 【0045】Also, when the ablation electrode 18 on the first clamping piece 16a and the ablation electrode 18 on the second clamping piece 16b are combined, the two combined ablation electrodes 18 may be displaced from each other in the protruding direction of the clamping piece 16. For example, the first ablation electrode 18a of the first clamping piece 16a and the second ablation electrode 18b of the second clamping piece 16b may be combined, the second ablation electrode 18b of the first clamping piece 16a and the third ablation electrode 18c of the second clamping piece 16b may be combined, and the third ablation electrode 18c of the first clamping piece 16a and the fourth ablation electrode 18d of the second clamping piece 16b may be combined. 【0046】 Also, the plurality of ablation electrodes 18 may be divided into a plurality of groups, and the voltage application target may be determined in units of groups. The method of grouping and the number of groups are not particularly limited, which is the same as in the case of the monopolar method application described above. Also, in the bipolar method application, sequential application may be performed, continuous application may be performed, or both may be performed. 【0047】 (Monopolar method application and bipolar method application using the clip portion 12 in the open state) FIG. 5 is a schematic diagram for explaining a combination of monopolar method application and bipolar method application using the clip portion 12 in the open state. For example, as shown in FIG. 5, the control unit 28 first executes monopolar method application. In this monopolar method application, as an example, after a voltage is applied between the first group to which the first ablation electrodes 18a to 18d on the first clamping piece 16a belong and the counter electrode plate 6, a voltage is applied between the second group to which the first ablation electrodes 18a to 18d on the second clamping piece 16b belong and the counter electrode plate 6. 【0048】Next, the control unit 28 performs bipolar voltage application. In this bipolar voltage application, as an example, a voltage is applied between the first ablation electrodes 18a of the first clamping piece 16a and the second clamping piece 16b, then a voltage is applied between the second ablation electrodes 18b of the first clamping piece 16a and the second clamping piece 16b, then a voltage is applied between the third ablation electrodes 18c of the first clamping piece 16a and the second clamping piece 16b, and then a voltage is applied between the fourth ablation electrodes 18d of the first clamping piece 16a and the second clamping piece 16b. 【0049】 By combining monopolar and bipolar application methods, the range over which an electric field can be generated can be changed. This makes it possible to form a region more reliably over a wider area. As a result, undesirable situations such as the generation of re-entry circuits can be suppressed. 【0050】 In each application method, the ablation electrodes 18 to which voltage is applied can be set as appropriate. That is, in the monopolar application method, the target of voltage application may be switched on an electrode-by-electrode basis, as shown in Figure 3(A), or all ablation electrodes 18 may be treated as a single unit to which voltage is applied, as shown in Figure 3(C). In the bipolar application method, two ablation electrodes 18 provided on the same clamping piece 16 may be combined, as shown in Figures 4(A) and 4(D), or a bipolar application method in which two ablation electrodes 18 provided on the same clamping piece 16 are targeted for voltage application may be combined with a bipolar application method in which two ablation electrodes 18 provided on different clamping pieces 16 are targeted for voltage application, as shown in Figures 4(C) and 4(F). Furthermore, the above-mentioned various modifications can be applied to the order of voltage application, the combination of ablation electrodes 18 to which voltage is applied simultaneously, sequential application, continuous application, etc. 【0051】The order in which monopolar and bipolar voltage applications are performed is not particularly limited; a monopolar application may be performed after a bipolar application. 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. 【0052】 (Monopolar application using the clip portion 12 in a closed state) Figures 6(A), 6(B), and 6(C) are schematic diagrams illustrating monopolar application using the clip portion 12 in a closed state. For example, as shown in Figure 6(A), the control unit 28 can control the power supply unit 26 to apply voltage between the ablation electrode 18 and the counter electrode plate 6, by sequentially applying voltage to each ablation electrode 18 on each clamping piece 16 of the clip portion 12 in a closed state. 【0053】 Furthermore, as shown in Figure 6(B), the control unit 28 can divide the multiple ablation electrodes 18 into multiple groups, switch the target to which voltage is applied on a group-by-group basis, and perform monopolar application. 【0054】 Furthermore, as shown in Figure 6(C), the control unit 28 can also control the power supply unit 26 to apply voltage between all ablation electrodes 18 and the counter electrode plate 6, treating all ablation electrodes 18 of the clip unit 12 as targets for simultaneous voltage application. 【0055】 The method of grouping the multiple ablation electrodes 18 and the number of groups are not particularly limited, the order of voltage application can be set as appropriate, and various settings can be adjusted, such as sequential application and continuous application being performed individually or in combination, which is the same as in the monopolar application method using the clip portion 12 in the open state. 【0056】(Bipolar application using the clip portion 12 in a closed state) Figures 7(A), 7(B), and 7(C) are schematic diagrams illustrating bipolar application using the clip portion 12 in a closed state. The control unit 28 can arbitrarily combine the multiple ablation electrodes 18 of the clip portion 12 in a closed state and control the power supply unit 26 to apply a voltage between the combined ablation electrodes 18. 【0057】 For example, as shown in Figure 7(A), the control unit 28 can combine two ablation electrodes 18 provided on the same clamping piece 16 and control the power supply unit 26 to apply a voltage between the two ablation electrodes 18. 【0058】 Furthermore, as shown in Figure 7(B), the control unit 28 can combine the ablation electrode 18 on the first clamping piece 16a and the ablation electrode 18 on the second clamping piece 16b, and control the power supply unit 26 to apply a voltage between the two ablation electrodes 18. In the closed clip section 12, unlike the open clip section 12, combinations of ablation electrodes 18 that are in contact with each other or excessively close together occur more reliably. Applying a voltage to such a combination would cause a short circuit between the two ablation electrodes 18, so it is necessary to exclude such combinations from bipolar voltage application. 【0059】 Examples of ablation electrode combinations 18 that are in contact with or excessively close to each other include combinations of ablation electrodes 18 in which at least a portion overlaps with each other in the direction of protrusion of the clamping piece 16. Therefore, the combination of ablation electrode 18 on the first clamping piece 16a and ablation electrode 18 on the second clamping piece 16b to which voltage is applied is such that the entire electrodes are offset from each other in the direction of protrusion of the clamping piece 16. 【0060】For example, first a voltage is applied between the first ablation electrode 18a of the first clamping piece 16a and the second ablation electrode 18b of the second clamping piece 16b, then a voltage is applied between the second ablation electrode 18b of the first clamping piece 16a and the third ablation electrode 18c of the second clamping piece 16b, then a voltage is applied between the third ablation electrode 18c of the first clamping piece 16a and the fourth ablation electrode 18d of the second clamping piece 16b. Subsequently, a voltage is applied between the fourth ablation electrode 18d of the first clamping piece 16a and the third ablation electrode 18c of the second clamping piece 16b, then a voltage is applied between the third ablation electrode 18c of the first clamping piece 16a and the second ablation electrode 18b of the second clamping piece 16b, and then a voltage is applied between the second ablation electrode 18b of the first clamping piece 16a and the first ablation electrode 18a of the second clamping piece 16b. 【0061】 Furthermore, as shown in Figure 7(C), the control unit 28 can also perform a combination of bipolar voltage application, where two ablation electrodes 18 provided on the same clamping piece 16 are the targets of voltage application, and bipolar voltage application, where two ablation electrodes 18 provided on different clamping pieces 16 are the targets of voltage application. 【0062】 Examples of biological tissue 2 that can be targeted for ablation using the closed clip portion 12 include the RA isthmus located between the inferior vena cava and the tricuspid valve on the right atrium side, and the mitral isthmus located between the left inferior pulmonary vein and the mitral valve annulus on the left atrium side. By performing ablation using the closed clip portion 12, the biological tissue 2 can be cauterized linearly. Therefore, by cauterizing areas where iatrogenic arrhythmias such as atrial tachycardia may occur if a wide area is cauterized with the closed clip portion 12, the occurrence of such arrhythmias can be suppressed. 【0063】The order in which the voltage is applied can be set as appropriate, the combination of the ablation electrodes 18 can be set as appropriate except for combinations that are in contact with each other or excessively close together, the targets to which the voltage is applied may be defined in groups, in which case there are no particular limitations on how the groups are divided or the number of groups, and various settings can be adjusted, such as sequential application and continuous application being carried out individually or in combination, which is the same as with bipolar application using the clip portion 12 in the open state. 【0064】 (Monopolar and bipolar application using the clip portion 12 in a closed state) Figure 8 is a schematic diagram illustrating the combination of monopolar and bipolar application using the clip portion 12 in a closed state. For example, as shown in Figure 8, the control unit 28 first performs monopolar application. In this monopolar application, as an example, a voltage is applied between the first group, to which the first ablation electrodes 18a to the fourth ablation electrodes 18d on the first clamping piece 16a belong, and the counter electrode plate 6, and then a voltage is applied between the second group, to which the first ablation electrodes 18a to the fourth ablation electrodes 18d on the second clamping piece 16b belong, and the counter electrode plate 6. Subsequently, the control unit 28 performs bipolar application. In this bipolar application, as an example, a voltage is applied between the ablation electrode 18 of the first clamping piece 16a and the ablation electrode 18 of the second clamping piece 16b. 【0065】 In each application method, the ablation electrodes 18 to which the voltage is applied can be set as appropriate. That is, in the monopolar application method, the target of voltage application may be switched on an electrode-by-electrode basis as shown in Figure 6(A), or all ablation electrodes 18 may be treated as a single unit to which the voltage is applied as shown in Figure 6(C). In the bipolar application method, two ablation electrodes 18 provided on the same clamping piece 16 may be combined as shown in Figure 7(A), or a bipolar application method in which two ablation electrodes 18 provided on the same clamping piece 16 are targeted for voltage application may be combined with a bipolar application method in which two ablation electrodes 18 provided on different clamping pieces 16 are targeted for voltage application as shown in Figure 7(C). 【0066】 The above-mentioned various setting adjustments can be applied to the voltage application sequence, the combination of ablation electrodes 18 to which voltage is applied simultaneously, sequential and continuous application, and the execution order and number of executions of monopolar and bipolar application. 【0067】 Furthermore, if the control unit 28 controls the power supply unit 26 to apply voltage to the ablation electrode 18 only when the clip portion 12 is in a closed state, for example, the ablation electrode 18 on each clamping piece 16 is an electrode piece that does not function as an electrode when the clip portion 12 is in an open state, and when the clip portion 12 is in a closed state, the electrode piece on one clamping piece 16 and the electrode piece on the other clamping piece 16 come together to form the ablation electrode 18, thereby enabling ablation. 【0068】 (Selection of electrodes based on impedance) The control unit 28 in this embodiment can apply a voltage for impedance measurement to the ablation electrode 18 and determine whether or not to use the ablation electrode 18 for ablation according to the measured impedance Z. This determination can be performed regardless of the open / closed state of the clip portion 12. It can also be performed when performing either monopolar or bipolar voltage application. 【0069】 When the clip portion 12 is positioned inside the patient's body, the ablation electrode 18 primarily contacts biological tissue 2. Depending on the surgical procedure, the ablation electrode 18 may also come into contact with blood, saline solution, or the atmosphere. Biological tissue 2 has lower conductivity than blood or saline solution. Therefore, the impedance Z generated when a voltage is applied between the ablation electrode 18 and the counter electrode plate 6 in these liquids is relatively high when the ablation electrode 18 is in contact with biological tissue 2, and relatively low when the ablation electrode 18 is not in contact with biological tissue 2, that is, when the entire exposed portion of the ablation electrode 18 is in contact with blood or saline solution. 【0070】Furthermore, the biological tissue 2 has higher conductivity than the atmosphere. Therefore, the impedance Z generated when a voltage is applied between the ablation electrode 18 and the counter electrode plate 6 in the atmosphere is relatively low when the ablation electrode 18 is in contact with the biological tissue 2, and relatively high when the ablation electrode 18 is not in contact with the biological tissue 2, that is, when the entire exposed portion of the ablation electrode 18 is in contact with the atmosphere. Thus, it is possible to determine whether or not the ablation electrode 18 is in contact with the biological tissue 2 using the impedance Z as an indicator. 【0071】 Therefore, the control unit 28 transmits a control signal CTL to the power supply unit 26, controlling the power supply unit 26 to apply a voltage for impedance measurement between the ablation electrode 18 and the counter electrode plate 6. The control unit 28 then acquires information, including the voltage value and current value obtained from the application of the voltage, via the power supply unit 26. This allows the control unit 28 to measure the impedance Z between the ablation electrode 18 and the counter electrode plate 6. The control unit 28 then 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 Zth. 【0072】 The reference impedance Z0 is the reference point, or zero point, impedance used to determine contact between the ablation electrode 18 and the biological tissue 2. For example, the reference impedance Z0 can be measured by applying an impedance measurement voltage between the two ablation electrodes 18 while the clip portion 12 is positioned inside the patient's body and it is guaranteed that the two ablation electrodes 18 are not in contact with the biological tissue 2. Alternatively, two reference electrodes specifically for measuring the reference impedance Z0 may be provided in positions on the clip portion 12 or shaft 10 where it is guaranteed that they will not come into contact with the biological tissue 2, and the reference impedance Z0 may be measured using these two reference electrodes. The reference impedance Z0 is measured in advance inside 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. 【0073】 When the difference ΔZ is greater than or equal to the threshold Zth, it can be determined that the ablation electrode 18 is in contact with the biological tissue 2. Blood and saline solution have extremely high conductivity compared to air. Also, biological tissue 2 has lower conductivity than blood and saline solution, but higher conductivity than air. For this reason, when the ablation electrode 18 comes into contact with biological tissue 2 while it is in blood or saline solution, the impedance Z changes in a direction that increases relative to the reference impedance Z0. On the other hand, when the ablation electrode 18 comes into contact with biological tissue 2 while it is in air, the impedance Z changes in a direction that decreases relative to the reference impedance Z0. 【0074】 Therefore, the increase or decrease in impedance Z when the ablation electrode 18 comes into contact with biological tissue 2, depending on whether a conductive liquid or air is present around the ablation electrode 18, is in opposite directions with respect to the reference impedance Z0. However, in either case, when the ablation electrode 18 comes into contact with biological tissue 2, the difference ΔZ exceeds the threshold Zth. Thus, when the difference ΔZ is greater than or equal to the threshold Zth, it can be determined that the ablation electrode 18 is in contact with biological tissue 2. 【0075】 When the ablation electrode 18 is in contact with the biological tissue 2, an electric field can be reliably generated by the biological tissue 2 compared to when there is no contact. Therefore, when the difference ΔZ is greater than or equal to a predetermined threshold Zth, the control unit 28 controls the power supply unit 26 to apply an ablation voltage to the ablation electrode 18 used to measure the impedance Z, that is, to perform ablation using the ablation electrode 18. When performing bipolar application using this ablation electrode 18, contact determination based on impedance Z is also performed on the other ablation electrode 18, so that bipolar application can be performed using only the ablation electrode 18 that is guaranteed to be in contact with the biological tissue 2. 【0076】On the other hand, when the difference ΔZ is less than the threshold Zth, it can be determined that the ablation electrode 18 is not in contact with the biological tissue 2. When the ablation electrode 18 is not in contact with the biological tissue 2, it is more difficult to effectively generate an electric field in the biological tissue 2 compared to when it is in contact with the biological tissue 2. Therefore, when the difference ΔZ is less than the threshold Zth, the control unit 28 controls the power supply unit 26 so as not to apply an ablation voltage to the ablation electrode 18 used to measure the impedance Z, that is, to avoid performing ablation using the ablation electrode 18. 【0077】 In this case, the control unit 28 may inform the user of the ablation system 1 of this fact by displaying on the display unit 30 that the ablation electrode 18 is not in contact with the biological tissue 2. This allows the user to take appropriate action, such as adjusting the position of the clip unit 12 so that the ablation electrode 18 makes contact with the biological tissue 2, or instructing the control unit 28 via the input unit 24 to switch the target of the ablation voltage application to another ablation electrode 18. Alternatively, the following control may be performed: First, a contact determination with the biological tissue 2 is performed for all ablation electrodes 18. Then, if the control unit 28 determines that the ablation electrode 18 to which the ablation voltage is scheduled to be applied is not in contact with the biological tissue 2, based on the user's instructions or the control program, it may switch to another ablation electrode 18 that has been determined to be in contact with the biological tissue 2 and perform the ablation. 【0078】 The control unit 28 may also control the power supply unit 26 to apply an impedance measurement voltage between the two ablation electrodes 18. In this case, when the difference ΔZ between the impedance Z between the two ablation electrodes 18 and the reference impedance Z0 is greater than or equal to the threshold Zth, it can be determined that both ablation electrodes 18 are in contact with the biological tissue 2. Therefore, the control unit 28 controls the power supply unit 26 to apply an ablation voltage to the two ablation electrodes 18. 【0079】On the other hand, when the difference ΔZ is less than the threshold Zth, it can be determined that at least one of the ablation electrodes 18 is not in contact with the biological tissue. In this case, for example, the control unit 28 controls the power supply unit 26 so that no ablation voltage is applied to either ablation electrode 18. The control unit 28 may also perform actions such as notifying the user or switching the target to which the voltage is applied, as described above. Regarding the switching of the target to which the voltage is applied, for example, the control unit 28 may combine one of the two ablation electrodes 18 that have undergone contact determination with an ablation electrode 18 other than these two ablation electrodes 18, and perform contact determination on this new combination. Then, if the control unit 28 determines that the two newly combined ablation electrodes 18 are in contact with the biological tissue 2, it may perform ablation using these two ablation electrodes 18. 【0080】 (Selection of electrodes based on pressure) The control unit 28 in this embodiment can determine whether or not to use the ablation electrode 18 for ablation depending on the pressure P applied to the ablation electrode 18. This determination can be performed regardless of the open / closed state of the clip portion 12. It can also be performed when performing either monopolar or bipolar application. 【0081】 When the pressure P applied to the ablation electrode 18 is equal to or greater than a predetermined threshold Pth, it can be determined that the ablation electrode 18 is in contact with the biological tissue 2. Therefore, when the pressure P is equal to or greater than the threshold Pth, the control unit 28 controls the power supply unit 26 to apply an ablation voltage to the ablation electrode 18, that is, to perform ablation using the ablation electrode 18. When performing bipolar application using the ablation electrode 18, contact determination based on pressure P is also performed on the other ablation electrode 18, so that bipolar application can be performed using only the ablation electrode 18 that is guaranteed to be in contact with the biological tissue 2. 【0082】On the other hand, when the pressure P is less than the threshold Pth, it can be determined that the ablation electrode 18 is not in contact with the biological tissue 2. When the pressure P is less than the threshold Pth, the control unit 28 controls the power supply unit 26 so as not to apply the ablation voltage to the ablation electrode 18, that is, to avoid performing ablation using the ablation electrode 18. In this case, the control unit 28 may perform actions such as notifying the user or switching the target to which the voltage is applied, as described above. 【0083】 The pressure P applied to the ablation electrode 18 can be measured using a known measurement method. For example, the pressure P can be measured by attaching a known pressure sensor to the ablation electrode 18. The threshold value Pth 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 held in the control unit 28. 【0084】 Furthermore, if multiple ablation electrodes 18 are divided into multiple groups and an ablation voltage is applied to each group, the contact determination of the ablation electrodes 18 based on the impedance Z and pressure P described above may be performed on a group basis. Alternatively, contact determination based on impedance Z and contact determination based on pressure P may be combined. In this case, the control unit 28 may determine that the ablation electrode 18 is in contact with the biological tissue only if both the contact determination based on impedance Z and the contact determination based on pressure P determine that the ablation electrode 18 is in contact with the biological tissue, or it may determine that the ablation electrode 18 is in contact with the 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. Additionally, contact determination may be performed periodically during ablation, and the ablation electrode 18 to be used may be switched according to the result of the determination. Furthermore, the ablation electrode 18 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 ablation electrode 18, the temperature of the ablation electrode 18, etc. 【0085】(Selection of application method based on impedance) The control unit 28 can also decide whether to perform monopolar application or bipolar application depending on the result of the contact determination using the impedance as an indicator as described above. That is, when the ablation electrode 18 is in contact with the biological tissue 2, a more reliable electric field can be generated in the biological tissue 2 by bipolar application compared to when there is no contact. Therefore, when the difference ΔZ between the measured impedance Z and the reference impedance Z0 is greater than or equal to the threshold Zth, the control unit 28 controls the power supply unit 26 to perform bipolar application using the ablation electrode 18. 【0086】 On the other hand, in bipolar application where the ablation electrode 18 is not in contact with the biological tissue 2, it is difficult to effectively generate an electric field in the biological tissue 2. Therefore, the control unit 28 controls the power supply unit 26 to perform monopolar application using the ablation electrode 18 when the difference ΔZ is less than the threshold Zth. With monopolar application, an electric field can be generated in the biological tissue compared to bipolar application, even if the ablation electrode 18 is not in contact with the biological tissue. 【0087】 When measuring impedance Z by applying a voltage for impedance measurement between two ablation electrodes 18, if the difference ΔZ is greater than or equal to the threshold Zth, the control unit 28 controls the power supply unit 26 to perform bipolar application using the two ablation electrodes 18. On the other hand, if the difference ΔZ is less than the threshold Zth, for example, the control unit 28 controls the power supply unit 26 to perform monopolar application for either ablation electrode 18. 【0088】The control unit 28 may control the power supply unit 26 to perform bipolar or monopolar application using the ablation electrode 18 that has been subjected to contact determination when the difference ΔZ is greater than or equal to the threshold Zth, and to perform monopolar application using the ablation electrode 18 when the difference ΔZ is less than the threshold Zth. In this way, by allowing the user to choose whether to perform bipolar or monopolar application when the ablation electrode 18 is in contact with the biological tissue 2, the flexibility of treatment using the ablation system 1 can be increased. For example, when the lesion is deep within the biological tissue 2, it may be preferable to perform monopolar application even when the ablation electrode 18 is in contact with the biological tissue 2. 【0089】 (Selection of application method based on pressure) The control unit 28 can also decide whether to perform monopolar application or bipolar application depending on the result of the contact determination using the pressure described above as an indicator. That is, when the pressure P applied to the ablation electrode 18 is greater than or equal to the threshold Pth, the control unit 28 controls the power supply unit 26 to perform bipolar application using the ablation electrode 18. On the other hand, when the pressure P is less than the threshold Pth, the control unit 28 controls the power supply unit 26 to perform monopolar application using the ablation electrode 18. 【0090】 The control unit 28 may control the power supply unit 26 to perform bipolar or monopolar application using the ablation electrode 18 that has been subjected to contact determination when the pressure P is equal to or greater than the threshold Pth, and to perform monopolar application using the ablation electrode 18 when the pressure P is less than the threshold Pth. This increases the flexibility of treatment using the ablation system 1. 【0091】Furthermore, contact detection may be performed periodically during ablation, and the application method may be switched between monopolar and bipolar depending on the result of the detection. In addition, the application method may be selected or switched depending on the number of times and duration that voltage is applied to the ablation electrode 18, the temperature of the ablation electrode 18, etc. 【0092】 The configuration of the surgical instrument 4 and the power supply unit 8 can be changed as appropriate. For example, the structure for opening and closing the clip portion 12 is not limited to sliding between the outer and inner tubes of the shaft 10. The clip portion 12 may also have a structure in which the first clamping piece 16a protrudes from the tip side of the shaft 10 in the axial direction of the shaft 10, and the second clamping piece 16b is rotatably connected to the base end of the first clamping piece 16a. In this case, the second clamping piece 16b can move closer to and further away from the first clamping piece 16a by rotating with its base end as a pivot point. In addition, some of the ablation electrodes 18 may be excluded from the application of the ablation voltage. In this case, the ablation electrodes 18 can be used for potential measurement or as spares when the ablation range is wide. In other words, not all of the ablation electrodes 18 on the clip portion 12 are necessarily subject to the application of the ablation voltage. 【0093】 Furthermore, the control of the power supply unit 26 by the control unit 28 may be implemented in hardware (circuit) or in software (program). If implemented in software, the software consists of a group of programs that cause a computer to execute each function. Each program may be pre-installed in the computer or installed in the computer from a network or recording medium. The power supply unit 26 may apply voltage to each ablation electrode 18 to generate monophase pulses. 【0094】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. 【0095】The embodiments may be specified by the items described below. [Item 1] An ablation system (1) for performing ablation of biological tissue (2) using irreversible electroporation, comprising: a shaft (10); a surgical instrument (4) having a shaft (10), a pair of clamping pieces (16) provided on the tip side of the shaft (10) and a clip portion (12) including at least one ablation electrode (18) provided on at least one of the clamping pieces (16), and an operating portion (22) provided on the proximal end side of the shaft (10) for opening and closing the clip portion (12); a counter electrode plate (6); a power supply unit (26) for applying voltage to at least one ablation electrode (18) and the counter electrode plate (6); and a control unit (28) for controlling the power supply unit (26) to perform monopolar application of voltage between at least one ablation electrode (18) and the counter electrode plate (6). [Item 2] The ablation system (1) of Item 1, wherein the clip section (12) has a plurality of ablation electrodes (18), and the control unit (28) controls the power supply unit (26) to perform a combination of bipolar application, where a voltage is applied between the ablation electrodes (18), and monopolar application. [Item 3] The ablation system (1) of Item 1 or Item 2, wherein the control unit (28) controls the power supply unit (26) to apply a voltage to the ablation electrodes (18) at least when the clip section (12) is in a closed state. [Item 4] The ablation system (1) of Item 3, wherein the control unit (28) controls the power supply unit (26) to apply a voltage to the ablation electrodes (18) both when the clip section (12) is in a closed state and when it is in an open state.[Item 5] An ablation system (1) according to any of Items 1 to 4, wherein the clip section (12) has a plurality of ablation electrodes (18), and the control unit (28) applies a voltage for impedance measurement between the ablation electrodes (18) and the counter electrode plate (6), or between the ablation electrodes (18) themselves to measure the impedance (Z), 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 ablation electrodes (18) and biological tissue (2), is greater than or equal to a predetermined threshold (Zth), an ablation voltage is applied to the ablation electrodes (18), and when the difference (ΔZ) is less than the threshold (Zth), the power supply unit (26) is controlled so as not to apply an ablation voltage to the ablation electrodes (18). [Item 6] An ablation system (1) according to any of Items 1 to 5, wherein the control unit (28) applies an ablation voltage to the ablation electrode (18) when the pressure (P) applied to the ablation electrode (18) is equal to or greater than a predetermined threshold (Pth), and controls the power supply unit (26) so as not to apply an ablation voltage to the ablation electrode (18) when the pressure (P) is less than the threshold (Pth). [Item 7] The ablation system (1) of Item 2, wherein the control unit (28) measures impedance (Z) by applying a voltage for impedance measurement between the ablation electrode (18) and the counter electrode plate (6), or between the ablation electrodes (18) themselves, and when the difference (ΔZ) between the measured impedance (Z) and the reference impedance (Z0), which is a reference point for determining contact between the ablation electrode (18) and the biological tissue (2), is greater than or equal to a predetermined threshold (Zth), the power supply unit (26) controls the power supply unit (26) to perform bipolar application using the ablation electrode (18) when the difference (ΔZ) is less than the threshold (Zth), and when the difference (ΔZ) is less than the threshold (Zth), the power supply unit (26) controls the power supply unit (26) to perform monopolar application using the ablation electrode (18).[Item 8] The ablation system (1) is provided with an input unit (24) for inputting a signal to a control unit (28) to instruct whether to perform bipolar or monopolar application, and the control unit (28) applies a voltage for impedance measurement between the ablation electrode (18) and the counter electrode plate (6), or between the ablation electrodes (18) themselves, to measure the impedance (Z), 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 ablation electrode (18) and the biological tissue (2), is greater than or equal to a predetermined threshold (Zth), the power supply unit (26) is controlled to perform application according to the signal using the ablation electrode (18), and when the difference (ΔZ) is less than the threshold (Zth), the power supply unit (26) is controlled to perform monopolar application using the ablation electrode (18), as described in Item 2. [Item 9] An ablation system (1) according to Item 2 or Item 7, wherein the control unit (28) controls the power supply unit (26) to perform bipolar application using the ablation electrode (18) when the pressure (P) applied to the ablation electrode (18) is equal to or greater than a predetermined threshold (Pth), and to perform monopolar application using the ablation electrode (18) when the pressure (P) is less than the threshold (Pth). [Item 10] The ablation system (1) is provided with an input unit (24) for inputting a signal to a control unit (28) to instruct whether to perform bipolar or monopolar application, and the control unit (28) controls the power supply unit (26) to perform application according to the signal using the ablation electrode (18) when the pressure (P) applied to the ablation electrode (18) is equal to or greater than a predetermined threshold (Pth), and to perform monopolar application using the ablation electrode (18) when the pressure (P) is less than the threshold (Pth), the ablation system (1) according to item 2 or item 8. 【0096】 This disclosure can be used in ablation systems. 【0097】1 Ablation system, 2 Biological tissue, 4 Surgical instruments, 6 Counter electrode plate, 10 Shaft, 12 Clip section, 16 Clamping piece, 18 Ablation electrode, 22 Operating section, 26 Power supply section, 28 Control section.

Claims

1. An ablation system for performing ablation of biological tissue using irreversible electroporation, comprising: a shaft; a surgical instrument having a shaft, a pair of clamping pieces provided on the tip side of the shaft and a clip portion including at least one ablation electrode provided on at least one of the clamping pieces, and an operating portion provided on the proximal end side of the shaft for opening and closing the clip portion; a counter electrode plate; a power supply unit for applying voltage to at least one of the ablation electrodes and the counter electrode plate; and a control unit for controlling the power supply unit to perform monopolar voltage application between at least one of the ablation electrodes and the counter electrode plate.

2. The ablation system according to claim 1, wherein the clip portion has a plurality of ablation electrodes, and the control unit controls the power supply unit to perform a combination of bipolar voltage application, in which a voltage is applied between the ablation electrodes, and monopolar voltage application.

3. The ablation system according to claim 1 or 2, wherein the control unit controls the power supply unit to apply a voltage to the ablation electrode when at least the clip portion is in a closed state.

4. The ablation system according to claim 3, wherein the control unit controls the power supply unit to apply a voltage to the ablation electrode both when the clip unit is in a closed state and when it is in an open state.

5. The ablation system according to claim 1 or 2, wherein the clip portion has a plurality of ablation electrodes, the control unit measures impedance by applying a voltage for impedance measurement between the ablation electrode and the counter electrode plate, or between the ablation electrodes themselves, and when the difference between the measured impedance and a reference impedance which is a reference point for determining contact of the ablation electrode with the biological tissue is greater than or equal to a predetermined threshold, the control unit applies an ablation voltage to the ablation electrode, and when the difference is less than the threshold, the power supply unit controls the power supply unit so as not to apply an ablation voltage to the ablation electrode.

6. The ablation system according to claim 1 or 2, wherein the control unit controls the power supply unit so as not to apply an ablation voltage to the ablation electrode when the pressure applied to the ablation electrode is above a predetermined threshold, and when the pressure is below the threshold.

7. The ablation system according to claim 2, wherein the control unit measures impedance by applying a voltage for impedance measurement between the ablation electrode and the counter electrode plate, or between the ablation electrodes themselves, and controls the power supply unit to perform the bipolar application using the ablation electrode when the difference between the measured impedance and a reference impedance which is a reference point for determining contact of the ablation electrode with the biological tissue is greater than or equal to a predetermined threshold, and performs the monopolar application using the ablation electrode when the difference is less than the threshold.

8. The ablation system according to claim 2, comprising: an input unit for inputting a signal to the control unit indicating whether to perform the bipolar application or the monopolar application; the control unit measuring impedance by applying a voltage for impedance measurement between the ablation electrode and the counter electrode plate, or between the ablation electrodes themselves; when the difference between the measured impedance and a reference impedance, which is a reference point for determining contact of the ablation electrode with the biological tissue, is greater than or equal to a predetermined threshold, the power supply unit is controlled to perform the application according to the signal using the ablation electrode; and when the difference is less than the threshold, the power supply unit is controlled to perform the monopolar application using the ablation electrode.

9. The ablation system according to claim 2 or 7, wherein the control unit controls the power supply unit to perform the bipolar application using the ablation electrode when the pressure applied to the ablation electrode is above a predetermined threshold, and to perform the monopolar application using the ablation electrode when the pressure is below the threshold.

10. The ablation system according to claim 2 or 8, wherein the ablation system includes an input unit for inputting a signal to the control unit indicating whether to perform the bipolar application or the monopolar application, and the control unit controls the power supply unit to perform the application according to the signal using the ablation electrode when the pressure applied to the ablation electrode is above a predetermined threshold, and to perform the monopolar application using the ablation electrode when the pressure is below the threshold.