Power supply device and ablation system

Abstract

This power supply device is provided with: a power supply unit that is electrically connected to a catheter having electrodes and that applies voltage to the electrodes so as to generate biphasic pulses BP; and a control unit that controls the power supply unit to generate, following on a first pulse set P1 in which positive-voltage phase pulses PVP and negative-voltage phase pulses NVP of the biphasic pulses BP spaced apart by a predetermined first interval A1 are continuous, a second pulse set P2 in which positive-voltage phase pulses PVP and negative-voltage phase pulses NVP spaced apart by a second interval A2 that differs from the first interval A1 are continuous.

Description

Power Supply and Ablation System

[0001] The present disclosure relates to a power supply and an ablation system.

[0002] Patent Document 1 discloses an ablation system including an ablation catheter and a pulse waveform generator that delivers voltage pulses to the ablation catheter.

[0003] Special table 2019-500170 publication

[0004] As a result of extensive research, the present inventors have come up with a novel technique for catheter ablation.

[0005] The present disclosure has been made in light of these circumstances, and its purpose is to provide a novel technique related to catheter ablation.

[0006] One aspect of the present disclosure is a power supply device comprising: a power supply unit electrically connected to a catheter having electrodes and configured to apply a voltage to the electrodes to generate biphasic pulses; and a control unit configured to control the power supply unit to generate a first pulse set in which a positive voltage phase pulse and a negative voltage phase pulse of the biphasic pulses are successively spaced a predetermined first interval apart, followed by a second pulse set in which the positive voltage phase pulse and the negative voltage phase pulse are successively spaced a second interval different from the first interval.

[0007] Another aspect of the present disclosure is an ablation system, comprising a catheter having an electrode and the power supply device of the above aspect.

[0008] Any combination of the above components, and conversion of the expression of the present disclosure into a method, device, system, etc., are also valid aspects of the present disclosure.

[0009] According to the present disclosure, a novel technique for catheter ablation can be provided.

[0010] Fig. 1 is a schematic diagram of an ablation system according to an embodiment; Fig. 2 is a perspective view of an electrode assembly; Fig. 3 is a diagram showing the timing of voltage application to each electrode; Fig. 4 is a schematic diagram showing an example of an interval between a positive voltage phase pulse and a negative voltage phase pulse; Fig. 5 is a schematic diagram showing another example of an interval between a positive voltage phase pulse and a negative voltage phase pulse.

[0011] The present disclosure will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from each drawing.

[0012] FIG. 1 is a schematic diagram of an ablation system 1 according to an embodiment. In FIG. 1, some of the components of the ablation system 1 are depicted as functional blocks. At least some of these functional blocks can be realized as a hardware configuration using elements and circuits such as a computer CPU and memory, and as a software configuration using a computer program or the like. Those skilled in the art will understand that these functional blocks can be realized in various ways by combining hardware and software.

[0013] The ablation system 1 performs a predetermined ablation on an affected area 2 of a patient. The affected area 2 may be, for example, an organ experiencing arrhythmia. The ablation system 1 may also be used for ablation on other affected areas 2. The ablation system 1 includes a catheter 4, a return electrode 6, and a power supply 8.

[0014] The catheter 4, as an example, includes a shaft 10, an electrode assembly 12, and a handle 14. The shaft 10 is formed of a flexible tubular body, and at least the distal end is inserted into the patient's body. The shaft 10 is made of a known flexible material, including resins such as polyolefin, polytetrafluoroethylene, polyether block amide, and polyamide. The shaft 10 has a multi-lumen structure, for example, having multiple lumens. Various thin wires (not shown), such as lead wires and operating wires, as well as an inner tube 22 (see FIG. 2), which will be described later, are inserted into the lumens.

[0015] An electrode assembly 12 is provided at the tip of the shaft 10. Fig. 2 is a perspective view of the electrode assembly 12. The electrode assembly 12 has a plurality of splines 16 and a plurality of electrodes 18. Fig. 1 illustrates the splines 16 in a folded state, while Fig. 2 illustrates the splines 16 in an expanded state.

[0016] Each spline 16 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 electrode assembly 12 shown in Figure 2 has, as an example, a first spline 16a, a second spline 16b, a third spline 16c, a fourth spline 16d, a fifth spline 16e, and a sixth spline 16f, but the number of splines 16 is not limited to six and may be any number as long as there is a plurality of splines. In the present disclosure, when there is no need to distinguish the first spline 16a to the sixth spline 16f from one another, they may be simply referred to as "splines 16."

[0017] The splines 16 are spaced apart from one another in the axial direction of the shaft 10. The distal end of each spline 16 is connected to a distal tip 20. The proximal end of each spline 16 is inserted into the shaft 10 from its distal end and fixed to the shaft 10. The distal tip 20 is connected to the distal end of an inner tube 22. The inner tube 22 is passed through the lumen of the shaft 10, and its proximal end is connected to the handle 14. The inner tube 22 can be advanced and retreated toward the distal end and proximal end of the shaft 10 by operating the handle 14.

[0018] When the inner tube 22 is retracted toward the proximal end of the shaft 10 with each spline 16 extending linearly, the distal tip 20 is displaced toward the proximal end of the shaft 10. This causes each spline 16 to curve and bulge outward, and the electrode assembly 12 assumes a basket shape. When the inner tube 22 is pushed toward the distal end of the shaft 10 with each spline 16 curved, the distal tip 20 is displaced toward the distal end of the shaft 10. This causes each spline 16 to become linear, and the electrode assembly 12 is folded. The term "basket shape" comes from the fact that the shape of the multiple splines 16 resembles the curved pattern on the surface of a basketball.

[0019] Each spline 16 is provided with a plurality of electrodes 18. The electrodes 18 are arranged at predetermined intervals along the length of the spline 16. Each electrode 18 is ring-shaped and made of a metal with good electrical conductivity, such as platinum, gold, silver, copper, aluminum, or stainless steel, or an alloy thereof. The electrode assembly 12 shown in FIG. 2 includes a first electrode 18a, a second electrode 18b, a third electrode 18c, and a fourth electrode 18d on each spline 16, as an example, but the number of electrodes 18 is not limited to four. In this disclosure, the first to fourth electrodes 18a to 18d may be simply referred to as "electrodes 18" when there is no need to distinguish them from one another.

[0020] The tip of a conductor (not shown) is connected to each electrode 18. The conductor is passed through the lumen of the shaft 10, and the proximal end is connected to a connector (not shown) of the handle 14 shown in Fig. 1. A power supply unit 8 is electrically connected to each conductor via the connector of the handle 14. As will be described in detail later, a voltage is applied to the plurality of electrodes 18 by the power supply unit 8.

[0021] The handle 14 is provided at the proximal end of the shaft 10, and is disposed outside the body when the catheter 4 is in use, to be grasped or operated by the operator. The handle 14 has a main body portion grasped by the operator and an operating portion for advancing and retracting the inner tube 22. By operating the operating portion, the inner tube 22 can be displaced toward the proximal end relative to the shaft 10, thereby unfolding the electrode assembly 12, which is in a folded state, in a direction intersecting the axis of the shaft 10. Furthermore, by operating the operating portion, the inner tube 22 can be displaced toward the distal end relative to the shaft 10, thereby unfolding the electrode assembly 12, which is in an unfolded state. A connector is provided on the main body portion. The catheter 4 may have an irrigation mechanism that sprays irrigation fluid, such as saline, from the distal end during ablation.

[0022] The return electrode 6 is attached to the patient's body surface during ablation. The return electrode 6 is also electrically connected to a power supply 8. During ablation, a voltage is applied to each electrode 18 and the return electrode 6, thereby performing ablation.

[0023] The power supply device 8 includes an input unit 24, a power supply unit 26, a control unit 28, and a display unit 30. The input unit 24 is configured with, for example, a dial, a button, a touch panel, etc., and is operated by the operator of the ablation system 1. The operator can input various setting values ​​and signals instructing operations to the power supply device 8 via the input unit 24. Note that the various setting values ​​may be set in advance, such as at the time of product shipment, and stored in the power supply device 8. Signals indicating the setting values, etc., are sent from the input unit 24 to the control unit 28.

[0024] The power supply unit 26 applies an ablation voltage V to the electrode 18 and the return electrode 6 in accordance with a control signal CTL sent from the control unit 28. ｏｕｔThe power supply unit 26 is configured with 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 executes predetermined arithmetic processing. The control unit 28 is configured with a microcomputer, for example. The control unit 28 controls the application of voltage Vout to the electrode 18 and the return electrode 6 by sending a control signal CTL to the power supply unit 26. The display unit 30 displays various types of information to the outside. The display unit 30 is configured with a liquid crystal display, a CRT display, an organic EL display, etc.

[0025] Next, the content of the control executed by the control unit 28 will be described. The ablation system 1 of this embodiment performs ablation on the affected area 2 by irreversible electroporation (IRE). Because IRE is non-thermal, it is possible to suppress damage to tissues and nerves located around the affected area 2. 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, and to suppress the occurrence of complications such as esophageal fistula and phrenic nerve paralysis.

[0026] IRE involves pulsed electric field ablation (PFA). PFA is an ablation technique that kills cells by applying a pulsed electric field generated by applying a high voltage to each electrode 18 and the return electrode 6, i.e., forms a lesion in the affected area 2. The electric field tends to be reflected at the boundaries between tissues. This prevents damage to adjacent tissues when the affected area is cauterized.

[0027] With the electrode assembly 12 inserted into the patient's body via a blood vessel or the like and positioned at the affected area 2, the control unit 28, for example, controls the power supply unit 26 to sequentially apply voltage to each electrode 18. FIG. 3 is a diagram showing the timing of voltage application to each electrode 18. Note that FIG. 3 also shows a schematic diagram of the interval between the positive voltage phase pulse and the negative voltage phase pulse applied to each electrode 18. This interval will be described in detail later with reference to FIG. 4. The sequential application of voltage to each electrode 18 can be confirmed, for example, by connecting an oscilloscope to each electrode 18.

[0028] The control unit 28 sequentially applies voltage to the first through third electrodes 18a through 18c provided on one spline 16. The control unit 28 then sequentially applies voltage to the first through third electrodes 18a through 18c provided on another spline 16. The control unit 28 repeats this sequential application until finally applying voltage to all of the first through third electrodes 18a through 18c of the electrode assembly 12. In this embodiment, the fourth electrode 18d on each spline 16 is excluded from the targets to which voltage is applied. The fourth electrode 18d is provided for potential measurement or as a spare in case the ablation range is wide. The fourth electrode 18d may be omitted.

[0029] Specifically, voltages are first applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the first spline 16a in this order. Next, voltages are applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the second spline 16b in this order. Next, voltages are applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the third spline 16c in this order. Next, voltages are applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the fourth spline 16d in this order. Next, voltages are applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the fifth spline 16e in this order. Finally, voltages are applied to the first electrode 18a, the second electrode 18b, and the third electrode 18c on the sixth spline 16f in this order. In FIG. 3, for convenience, the 18 electrodes 18 from the first electrode 18a of the first spline 16a to the third electrode 18c of the sixth spline 16f are numbered consecutively from 1 to 18.

[0030] In this embodiment, the power supply unit 26 applies a voltage to each electrode 18 to generate a biphasic pulse (bipolar pulse). Therefore, a positive voltage phase pulse and a negative voltage phase pulse are applied to each electrode 18, and the polarity of each electrode 18 alternates. The voltage amplitude Am is, for example, 1000 V or more and 4000 V or less. The pulse width Δp is, for example, 0.1 μs or more and 100 μs or less.

[0031] In this embodiment, the sequential application of voltage to all electrodes 18 to be supplied with power in the electrode assembly 12, i.e., the first electrodes 18a to the third electrodes 18c on the first spline 16a to the sixth spline 16f, is considered one revolution. The control unit 28 controls the power supply unit 26 to execute the sequential application of voltage for multiple revolutions. The control unit 28 also controls the power supply unit 26 to repeat the sequential application of voltage for multiple sets, with multiple revolutions being considered one set. The number of revolutions in one set and the number of repeated sets can be appropriately set based on experiments or the like by the designer. For example, the number of revolutions in one set is 2 to 1,000 revolutions, and the number of sets is 2 to 100 sets. Note that the number of revolutions and the number of sets may be one revolution and one set, respectively.

[0032] By sequentially applying a voltage to each electrode 18, it is possible to increase the region that can be formed by each electrode 18 compared to when a voltage is applied to all of the multiple electrodes 18 simultaneously. This is thought to be because when a voltage is applied to all of the multiple electrodes 18 at once, the current is dispersed among the multiple electrodes 18, resulting in a decrease in current density, whereas when a voltage is applied sequentially to each electrode 18, the current is concentrated in one electrode 18, resulting in an increase in current density. Furthermore, by sequentially applying a voltage to the multiple electrodes 18 at intervals, it is possible to suppress body movements of the patient caused by PFA.

[0033] Next, the interval between the positive voltage phase pulse PVP and the negative voltage phase pulse NVP applied to each electrode 18 will be described. FIG. 4 is a schematic diagram showing an example of the interval between the positive voltage phase pulse PVP and the negative voltage phase pulse NVP. In this embodiment, the control unit 28 controls the power supply unit 26 to generate the second pulse set P2 following the first pulse set P1. In other words, the first pulse set P1 and the second pulse set P2 are consecutive to each other. The first pulse set P1 and the second pulse set P2 each correspond to one biphasic pulse BP.

[0034] In the first pulse set P1, the positive voltage phase pulse PVP and the negative voltage phase pulse NVP of the biphasic pulse BP are successively spaced apart by a predetermined first interval A1. In the second pulse set P2, the positive voltage phase pulse PVP and the negative voltage phase pulse NVP are successively spaced apart by a second interval A2 different from the first interval A1. Preferably, one of the first interval A1 and the second interval A2 is at least twice as long as the other. In the example shown in FIG. 4, the second interval A2 is at least twice as long as the first interval A1. Note that in each pulse set, the negative voltage phase pulse NVP may be generated before the positive voltage phase pulse PVP. Naturally, the trailing pulse of a leading pulse set does not also serve as the leading pulse of the trailing pulse set.

[0035] For example, the control unit 28 controls the power supply unit 26 to alternately generate the first pulse set P1 and the second pulse set P2. As an example, the first pulse set P1 is generated by the first electrode 18a on the first spline 16a, the second pulse set P2 is generated by the second electrode 18b, and the first pulse set P1 is generated by the third electrode 18c. Subsequently, the second pulse set P2 is generated by the first electrode 18a on the second spline 16b, the first pulse set P1 is generated by the second electrode 18b, and the second pulse set P2 is generated by the third electrode 18c. This repetition of the first pulse set P1 and the second pulse set P2 is also performed for the first electrode 18a on the third spline 16c and thereafter.

[0036] The control unit 28 may also control the power supply unit 26 as follows. FIG. 5 is a schematic diagram showing another example of the interval between the positive voltage phase pulse PVP and the negative voltage phase pulse NVP. That is, the control unit 28 controls the power supply unit 26 to generate a third pulse set P3 following the first pulse set P1 and the second pulse set P2. The third pulse set P3 corresponds to a biphasic pulse BP, similar to the first pulse set P1 and the second pulse set P2. In the third pulse set P3, the positive voltage phase pulse PVP and the negative voltage phase pulse NVP are successively spaced apart by a third interval A3 that is different from the first interval A1 and the second interval A2. As an example, the third interval A3 is longer than the first interval A1 and the second interval A2.

[0037] For example, the control unit 28 controls the power supply unit 26 to repeat the first pulse set P1, the second pulse set P2, and the third pulse set P3 in this order. As an example, the first pulse set P1 is generated by the first electrode 18a on the first spline 16a, the second pulse set P2 is generated by the second electrode 18b, and the third pulse set P3 is generated by the third electrode 18c. Subsequently, the first pulse set P1 is generated by the first electrode 18a on the second spline 16b, the second pulse set P2 is generated by the second electrode 18b, and the third pulse set P3 is generated by the third electrode 18c. This repetition of the first pulse set P1 to the third pulse set P3 is also performed for the first electrode 18a on the third spline 16c and thereafter.

[0038] The relationship between the lengths of the first interval A1, the second interval A2, and the third interval A3 is not limited to an increasing relationship in this order. For example, the first interval A1, the second interval A2, and the third interval A3 may be shorter in this order. Furthermore, the third interval A3 may be longer than one of the first interval A1 and the second interval A2 and shorter than the other. Furthermore, the third interval A3 may be the same length as the first interval A1 or the second interval A2. Furthermore, the first interval A1 and the second interval A2 may vary within the repetition period as long as consecutive pulses do not have the same length. Similarly, the third interval A3 may vary within the repetition period. Furthermore, an nth pulse set (n is an integer greater than or equal to 4) in which a positive voltage phase pulse PVP and a negative voltage phase pulse NVP are consecutive with an nth interval between them may be generated. The relationship of the nth interval to the first interval A1 and the second interval A2 is the same as that of the third interval A3.

[0039] Furthermore, when the interval between adjacent pulse sets is interval T, the relationship in magnitude between interval T and the first interval A1 to third interval A3 satisfies, for example, the following condition. That is, interval T is longer than the interval between the positive voltage phase pulse PVP and the negative voltage phase pulse NVP in two adjacent pulse sets. For example, interval T between first pulse set P1 and second pulse set P2 is longer than first interval A1 and second interval A2. Furthermore, interval T between second pulse set P2 and third pulse set P3 is longer than second interval A2 and third interval A3. As a more preferred example, interval T is at least twice, and more preferably 5 to 50 times, the longer of the intervals between the positive voltage phase pulse PVP and the negative voltage phase pulse NVP in two adjacent pulse sets. For example, when the first interval A1 is larger than the second interval A2, the interval T between the first pulse set P1 and the second pulse set P2 is preferably at least twice the first interval A1, and more preferably at least 5 times and at most 50 times the first interval A1.

[0040] In addition, in the present embodiment, a voltage is applied to all of the electrodes 18 to be supplied with power on one spline 16 (i.e., the first electrode 18a to the third electrode 18c), and then the power supply destination moves to the electrodes 18 on the next spline 16. However, the order of power supply is not limited as long as voltage is ultimately applied to all of the electrodes 18 to be supplied with power in the electrode assembly 12. For example, a voltage may be applied to some of the electrodes 18 to be supplied with power on one spline 16, and then the power supply destination may move to the electrodes 18 on the next spline 16. As an example, a voltage may be applied sequentially to the first electrodes 18a on each spline 16, then to the second spline 16b on each spline 16, and finally to the third spline 16c on each spline 16.

[0041] Furthermore, the order in which current is supplied to the first electrodes 18a to the third electrodes 18c on each spline 16 is not limited. The order in which current is supplied to the first electrodes 18a to the third electrodes 18c may differ for each spline 16. The order in which current is supplied to the first spline 16a to the sixth spline 16f is also not limited. Furthermore, some splines 16 may be excluded from the power supply targets. Furthermore, a voltage may be applied to the same electrode 18 multiple times in succession, in order to each electrode 18. Furthermore, the electrodes 18 may be divided into multiple electrode groups, the number of which is less than the number of electrodes 18, and voltage may be applied to each electrode group sequentially. When an electrode group includes two or more electrodes 18, applying a voltage to that electrode group results in the voltage being applied to each electrode 18 simultaneously. The same electrode 18 may be assigned to two or more different electrode groups.

[0042] Furthermore, the shapes and numbers of the splines 16 and the electrodes 18 are not limited. There may be only one electrode 18. Furthermore, the catheter 4 may not have splines 16 at the tip of the shaft 10, and the electrodes 18 may be disposed on the shaft 10.

[0043] Furthermore, the configurations of the catheter 4 and the power supply device 8 can be modified as appropriate. For example, the distal end of the shaft 10 of the catheter 4 may be bendable in one direction or multiple directions by operating the handle 14. The control of the power supply unit 26 by the control unit 28 may be realized by hardware (circuitry) or software (program). When realized by software, the software is composed of a group of programs for causing a computer to execute each function. Each program may be, for example, pre-installed in the computer, or may be installed into the computer from a network or a recording medium.

[0044] The embodiments of the present disclosure have been described in detail above. The above-described embodiments merely illustrate specific examples of implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design modifications, such as changing, adding, or deleting components, are possible within the scope of the concept of the present disclosure defined in the claims. A new embodiment with design modifications will combine the effects of the combined embodiments and modifications. In the above-described embodiments, the content that allows such design modifications is emphasized by using notations such as "in this embodiment" or "in this embodiment," but design modifications are also permitted even in content without such notation. Any combination of the components included in each embodiment is also valid as an aspect of the present disclosure. Hatching on cross sections in the drawings does not limit the material of the hatched object.

[0045] Embodiments may be specified by the following items: [Item 1] A power supply device (8) comprising: a power supply unit (26) electrically connected to a catheter (4) having electrodes (18) and applying a voltage to the electrodes (18) to generate biphasic pulses; and a control unit (28) that controls the power supply unit (26) to generate a first pulse set (P1) in which a positive voltage phase pulse (PVP) and a negative voltage phase pulse (NVP) in the biphasic pulse (BP) successively have a predetermined first interval (A1) between them, followed by a second pulse set (P1) in which the positive voltage phase pulse (PVP) and the negative voltage phase pulse (NVP) successively have a second interval (A2) different from the first interval (A1). [Item 2] The power supply device (8) according to item 1, wherein one of the first interval (A1) and the second interval (A2) is at least twice as long as the other. [Item 3] An ablation system (1) comprising: a catheter (4) having an electrode (18); and a power supply device (8) according to item 1 or 2.

[0046] The present disclosure may be utilized in power supply devices and ablation systems.

[0047] 1 Ablation system, 4 Catheter, 8 Power supply device, 18 Electrode, 26 Power supply unit, 28 Control unit, A1 First interval, A2 Second interval, BP Biphasic pulse, NVP Negative voltage phase pulse, PVP Positive voltage phase pulse, P1 First pulse set, P2 Second pulse set.

Claims

1. A power supply device comprising: a power supply unit electrically connected to a catheter having electrodes and applying a voltage to the electrodes to generate biphasic pulses; and a control unit that controls the power supply unit to generate a first pulse set in which a positive voltage phase pulse and a negative voltage phase pulse in the biphasic pulses successively separated by a predetermined first interval, followed by a second pulse set in which the positive voltage phase pulse and the negative voltage phase pulse successively separated by a second interval different from the first interval.

2. The power supply device according to claim 1, wherein one of the first interval and the second interval is at least twice as long as the other.

3. An ablation system comprising: a catheter having an electrode; and a power supply device according to claim 1 or 2.

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