Catheter system and shape ascertaining assistance method

Abstract

This catheter system includes: a catheter having a long shaft that has a lumen, a shape variation mechanism provided on the distal end side of the shaft, and a handle 14 provided on the proximal end side of the shaft; and a shape ascertaining assistance part 40 for outputting a shape signal related to the shape assumed by the shape variation mechanism. The handle 14 has a slide part 34. The catheter has a displacement transmission member 22 that is displaced together with the slide part 34 to cause the shape variation mechanism to deform. The shape ascertaining assistance part 40 has at least two terminal parts electrically connected to at least two measurement points, where the impedance between the measurement points changes due to the displacement of the slide part 34. The shape ascertaining assistance part 40 applies a voltage between the terminal parts and measures the impedance, and determines the shape signal by utilizing the fact that the impedance changes due to the displacement of the slide part 34.

Description

Catheter System and Shape Recognition Support Method

[0001] The present disclosure relates to a catheter system and a shape recognition support method.

[0002] Conventionally, a catheter having a shape-variable mechanism whose shape changes at the tip of a shaft has been known (see, for example, Patent Document 1). This catheter includes a shaft having a lumen, a distal electrode assembly as a shape-variable mechanism provided on the distal end side of the shaft, and a handle provided on the proximal end side of the shaft. A cable was passed through the lumen of the shaft, the distal end side of the cable was connected to the distal electrode assembly, and the proximal end side of the cable was connected to the handle. Then, by sliding the slide portion provided on the handle, the cable was displaced in the axial direction of the shaft to deform the distal electrode assembly.

[0003] Japanese Patent Publication No. 10-503700

[0004] In a situation where the shape-variable mechanism is inserted into a patient's body, it is difficult to confirm the shape taken by the shape-variable mechanism. Even if the operator of the catheter can estimate the shape from the position of the slide portion on the handle at hand, it is not easy to grasp the shape quickly and accurately. Also, when multiple people are involved in the operation, etc., people other than the operator may want to grasp the shape of the shape-variable mechanism. However, since it is difficult for people other than the operator to confirm the position of the slide portion, it is not even easy to estimate the shape.

[0005] The present disclosure has been made in view of such a situation, and an object thereof is to provide a technique for assisting in grasping the shape taken by a shape-variable mechanism provided in a catheter.

[0006] One aspect of the present disclosure is a catheter system. The system comprises a catheter having a long shaft having a lumen, a shape-changing mechanism provided at the tip of the shaft, and a handle provided at the proximal end of the shaft, and a shape-gathering support unit that outputs a shape signal relating to the shape taken by the shape-changing mechanism. The handle has a sliding portion operated by an operator. The catheter has a displacement transmission member positioned within the lumen and connected to the sliding portion and the shape-changing mechanism, which displaces together with the sliding portion to deform the shape-changing mechanism. The shape-gathering support unit has at least two terminals electrically connected to at least two measurement points where the impedance between the measurement points changes due to the displacement of the sliding portion, and measures the impedance by applying a voltage between each terminal and determines a shape signal by utilizing the fact that the impedance changes due to the displacement of the sliding portion.

[0007] Another aspect of the present disclosure is a shape recognition support method for a catheter having a long shaft with a lumen, a shape-changing mechanism provided at the tip of the shaft, and a handle provided at the proximal end of the shaft, which assists in recognizing the shape taken by the shape-changing mechanism. The handle has a sliding portion operated by an operator. The catheter has a displacement transmission member placed in the lumen and connected to the sliding portion and the shape-changing mechanism, which displaces together with the sliding portion to deform the shape-changing mechanism. The shape recognition support method includes measuring the impedance by applying a voltage between at least two measurement points where the impedance between the measurement points changes due to the displacement of the sliding portion, and presenting shape information regarding the state taken by the shape-changing mechanism by utilizing the fact that the impedance changes due to the displacement of the sliding portion.

[0008] Any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid forms of this disclosure.

[0009] According to this disclosure, it is possible to understand the shape taken by the shape-changing mechanism provided in the catheter.

[0010] This is a schematic diagram of the catheter system according to Embodiment 1. Figure 2(A) is a perspective view of the shape-changing mechanism taking the first unfolded shape. Figure 2(B) is a side view of the shape-changing mechanism taking the first unfolded shape. Figure 3(A) is a perspective view of the shape-changing mechanism taking the second unfolded shape. Figure 3(B) is a side view of the shape-changing mechanism taking the second unfolded shape. This is a plan view of the handle. This is a diagram showing the internal structure of the handle and the shape-grasping support unit. This is a diagram showing the internal structure of the handle and the shape-grasping support unit according to Embodiment 2. Figure 7(A) is a diagram showing the internal structure of the handle and the shape-grasping support unit according to Embodiment 3. Figures 7(B) and 7(C) are schematic diagrams illustrating the change in the positional relationship between the two terminal parts and the conductive and insulating parts due to the displacement of the sliding part.

[0011] 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.

[0012] (Embodiment 1) Figure 1 is a schematic diagram of a catheter system 1 according to Embodiment 1. In Figure 1, some of the components of the catheter system 1 are depicted as functional blocks. At least some of these functional blocks can be realized in hardware configuration by elements and circuits such as a computer's CPU and memory, and in software configuration by a computer program, etc. It will be understood by those skilled in the art that these functional blocks can be realized in various forms by combinations of hardware and software. Also, in Figure 1, the slide portion 34 of the handle 14 is not shown.

[0013] Catheter system 1 is an ablation system that performs ablation on a patient's affected area 2, for example. Examples of affected area 2 include organs where arrhythmias occur. Catheter system 1 may also be used for ablation of other affected areas 2, or for procedures other than ablation. Catheter system 1 comprises a catheter 4, a counter electrode 6, and a power supply 8.

[0014] The catheter 4 comprises a shaft 10, a shape-changing mechanism 12, and a handle 14. The shaft 10 is a long, flexible tubular body, with at least its tip 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 lumen 11 (see Figure 2(A), etc.). A displacement transmission member 22 (see Figure 2(A), etc.) is inserted through the lumen 11. The shaft 10 is also provided with a lumen (not shown) through which various thin wires (not shown), such as conductors, are inserted.

[0015] A shape-changing mechanism 12 is provided at the tip of the shaft 10. Figure 2(A) is a perspective view of the shape-changing mechanism 12 in its first unfolded shape. Figure 2(B) is a side view of the shape-changing mechanism 12 in its first unfolded shape. Figure 3(A) is a perspective view of the shape-changing mechanism 12 in its second unfolded shape. Figure 3(B) is a side view of the shape-changing mechanism 12 in its second unfolded shape. Note that Figure 1 shows the shape-changing mechanism 12 in its folded shape.

[0016] The shape-changing mechanism 12 of this embodiment is, as an example, an electrode assembly having a plurality of splines 16 and a plurality of electrodes 18. 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 shape-changing mechanism 12 of this embodiment has five splines 16, but the number of splines 16 is not limited to five and may be multiple.

[0017] Each spline 16 is arranged at intervals from each other in the direction of the axis of the shaft 10. The tip end of each spline 16 is connected to the tip 20. The base end of each spline 16 is inserted into the shaft 10 from the tip end and fixed to the shaft 10. The tip end of the displacement transmission member 22 is connected to the tip 20. As an example, the displacement transmission member 22 is made up of a long tubular or rod-shaped body. The displacement transmission member 22 is placed inside the lumen 11, with its tip end connected to the shape-changing mechanism 12 via the tip 20, and its base end connected to the sliding portion 34 of the handle 14 (see Figure 4, etc.).

[0018] The displacement transmission member 22 can move forward and backward toward the tip and base ends of the shaft 10 by the displacement of the sliding portion 34. As shown in Figure 1, when the shape-changing mechanism 12 is in a folded shape with each spline 16 folded, in other words, a linear shape, the displacement of the sliding portion 34 toward the base end of the shaft 10 causes the displacement transmission member 22 to be pulled toward the base end of the shaft 10, causing the tip 20 to be displaced toward the base end of the shaft 10. As a result, the shape-changing mechanism 12 curves so that each spline 16 bulges outward, becoming an unfolded shape. Also, when the shape-changing mechanism 12 is in an unfolded shape, the displacement of the sliding portion 34 toward the tip of the shaft 10 causes the displacement transmission member 22 to be pushed toward the tip of the shaft 10, causing the tip 20 to be displaced away from the base end of the shaft 10. As a result, the shape-changing mechanism 12 returns to its folded shape.

[0019] The shape-changing mechanism 12 can switch between a first unfolded shape, shown in at least Figures 2(A) and 2(B), and a second unfolded shape, shown in Figures 3(A) and 3(B), depending on the amount of displacement of the displacement transmission member 22. One example of the first unfolded shape is a so-called basket shape, in which a plurality of splines 16 are curved to a predetermined degree. The term "basket shape" comes from the fact that the shape of the curved plurality of splines 16 resembles the curved pattern on the surface of a basketball. One example of the second unfolded shape is a so-called flower shape, in which the plurality of splines 16 are curved more sharply than in the first unfolded shape. The term "flower shape" comes from the fact that the shape of the curved plurality of splines 16 resembles the shape of an open flower.

[0020] Each spline 16 in the second unfolded shape has a portion with greater curvature than in the first unfolded shape. In other words, the curvature of the portion with the maximum curvature in the second unfolded shape is greater than the curvature of the portion with the maximum curvature in the first unfolded shape. The shape-changing mechanism 12 can also take on a shape of bulge between the folded shape and the first unfolded shape, or between the first unfolded shape and the second unfolded shape, depending on the amount of displacement of the displacement transmission member 22. In this embodiment, the shape-changing mechanism 12 takes on the second unfolded shape when the displacement transmission member 22 is pulled in to the furthest base end, but the configuration is not limited to this. The shape-changing mechanism 12 may take on the second unfolded shape before the displacement transmission member 22 is pulled in to the furthest base end.

[0021] Each spline 16 is provided with at least one electrode 18. In this embodiment, as an example, each spline 16 is provided with multiple electrodes 18, more specifically, four electrodes 18. Each electrode 18 is arranged at a predetermined distance from each other in the longitudinal direction of the spline 16. Each electrode 18 is ring-shaped and made of a highly conductive metal such as platinum, gold, silver, copper, aluminum, or stainless steel, or an alloy thereof. The tip end of a conductor (not shown) is connected to each electrode 18. The conductor is passed through the lumen of the shaft 10, and its base end is connected to a connector 38 of the handle 14 shown in Figure 1 (see Figure 4). A power supply 8 is electrically connected to each conductor via the connector 38 of the handle 14. Power for ablation is supplied to each electrode 18 from the power supply 8.

[0022] Returning to Figure 1, the handle 14 is located on the proximal end of the shaft 10 and is positioned outside the body when the catheter 4 is in use, and is grasped or manipulated by the operator. The structure of the handle 14 will be described in detail later. The counter electrode 6 is attached to the patient's body surface during ablation. The counter electrode 6 is also electrically connected to the power supply unit 8. Power for ablation is supplied to the counter electrode 6 from the power supply unit 8.

[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 catheter system 1. The user can input various setting values ​​and signals to instruct operations to the power supply unit 8 via the input unit 24. Note that various setting values ​​may be pre-set and stored in the power supply unit 8 at the time of product shipment, etc. Signals indicating the setting values, etc., are sent from the input unit 24 to the control unit 28.

[0024] The power supply unit 26 applies an ablation voltage V to the multiple electrodes 18 and the counter electrode plate 6 according to the control signal CTL sent from the control unit 28. ｏｕｔ A voltage is 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 the electrode 18 and the 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] The control unit 28 performs ablation on the affected area 2 using, for example, irreversible electroporation (IRE). Because IRE is non-thermal, it can minimize damage to surrounding tissues and nerves. For example, when performing pulmonary vein dissection to treat atrial fibrillation, it can suppress damage to the esophagus and phrenic nerve around the affected area, thereby preventing complications such as esophageal fistula and phrenic nerve paralysis. Pulsed electric field ablation (PFA) is performed in IRE. PFA is an ablation technique that kills cells by applying a pulsed electric field generated by applying a high voltage between each electrode 18 and the counter electrode plate 6, or between the electrodes 18 themselves, thereby forming a region (lesion) in the affected area 2. The electric field tends to reflect at the boundaries between tissues. Therefore, it can suppress damage to adjacent tissues when the affected area is ablated.

[0026] Once the shape-variable mechanism 12 is inserted into the patient's body via a blood vessel or the like and positioned in the affected area 2, the control unit 28 controls the power supply unit 26 to apply voltage to each electrode 18 and the counter electrode plate 6. For example, the control unit 28 controls the power supply unit 26 to perform monopolar application (also called unipolar application), bipolar application, or both. In monopolar application, voltage is applied between the electrode 18 and the counter electrode plate 6. In bipolar application, voltage is applied between the electrodes 18. The order in which voltage is applied to each electrode 18, the number and combination of electrodes 18 to which voltage is applied simultaneously, and the number of times voltage is applied consecutively to the same electrode 18 can be appropriately set based on the designer's empirical knowledge or experiments and simulations conducted by the designer. Alternatively, a second catheter 4 may be used in place of or in addition to the counter electrode plate 6, and voltage may be applied between the electrodes 18 of the two catheters 4.

[0027] Next, the structure of the handle 14 and the shape-grasping support unit 40 will be described. Figure 4 is a plan view of the handle 14. Figure 5 is a diagram showing the internal structure of the handle 14 and the shape-grasping support unit 40. The handle 14 has a main body 32, a sliding part 34, a support part 36, and a connector 38. The main body 32 is, for example, a cylindrical body extending in the axial direction of the shaft 10, and is grasped by the operator of the catheter 4. A connector 38 is provided on the proximal end side of the main body 32. The shaft 10 is connected to the tip side of the main body 32.

[0028] The sliding portion 34 is a mechanism for displacing the displacement transmission member 22 in the axial direction of the shaft 10, and is operated by an operator. When the sliding portion 34 is operated, the displacement transmission member 22 is displaced together with the sliding portion 34, thereby deforming the shape variable mechanism 12. The support portion 36 supports the sliding portion 34 so that it can slide in the axial direction of the shaft 10. The support portion 36 in this embodiment has a groove, in other words a rail, that extends in the axial direction of the shaft 10 inside the main body portion 32. This groove is exposed to the outside of the main body portion 32 through an opening provided on the side surface of the main body portion 32. The sliding portion 34 can be fitted into this groove from the outside of the main body portion 32 and slide along the groove.

[0029] For example, the operator of the catheter 4 can deform the shape-changing mechanism 12 by grasping the main body 32 with the palm and several fingers excluding the thumb, and sliding the slide part 34 with the thumb. As an example, when the slide part 34 is at the tip of the groove of the support part 36, the displacement transmission member 22 is pushed out as far as the tip of the shaft 10, and the shape-changing mechanism 12 takes on a folded shape. Also, when the slide part 34 is in the middle of the groove, the displacement transmission member 22 is pulled in by a predetermined amount toward the base end of the shaft 10, and the shape-changing mechanism 12 takes on a first unfolded shape. Furthermore, when the slide part 34 is located toward the base end of the groove, the displacement transmission member 22 is pulled in as far as the base end of the shaft 10, and the shape-changing mechanism 12 takes on a second unfolded shape.

[0030] The catheter system 1 includes a shape recognition support unit 40 that assists in understanding the shape taken by the shape variable mechanism 12. In this embodiment, the shape recognition support unit 40 consists of a power supply unit 26, a control unit 28, and a display unit 30. At least two measurement points are set on the catheter 4. The two measurement points are set at positions where the impedance between each measurement point changes due to the displacement of the slide unit 34. The shape recognition support unit 40 has at least two terminals electrically connected to each measurement point. The shape recognition support unit 40 then applies a voltage between each terminal to measure the impedance, and using the fact that the impedance changes due to the displacement of the slide unit 34, it determines a shape signal related to the shape taken by the shape variable mechanism 12 and outputs it to, for example, the display unit 30.

[0031] The handle 14 of this embodiment has a first conductive member 42 on which a first measurement point M1 is set, and a second conductive member 44 on which a second measurement point M2 is set. The first conductive member 42 is made of a metal such as SUS and is provided on the slide portion 34. For example, the first conductive member 42 is a support column provided on the back surface of the slide portion 34, that is, on the side opposite to the surface that the operator touches, and is inserted into a groove of the support portion 36. The displacement transmission member 22 is connected to the first conductive member 42. Preferably, the first conductive member 42 and the displacement transmission member 22 are electrically insulated, or the displacement transmission member 22 is made of an insulating material. The second conductive member 44 is made of a metal such as SUS and is provided on the support portion 36 and extends in the sliding direction of the slide portion 34. For example, the second conductive member 44 is a metal plate laid on the bottom surface of the groove of the support portion 36 and extending in the axial direction of the shaft 10. Then, the second measurement point M2 is set on one end of the second conductive member 44, in this embodiment, on the base end. For example, the second conductive member 44 has a tab portion that extends outside the groove of the support portion 36, and this tab portion is designated as the second measurement point M2. Alternatively, the second measurement point M2 may be set on the tip end of the second conductive member 44.

[0032] The sliding portion 34 slides from one end to the other of the second conductive member 44 with the first conductive member 42 electrically connected to the second conductive member 44. The shape-grasping support unit 40 has a first terminal portion 46 and a second terminal portion 48. The first terminal portion 46 is electrically connected to the first conductive member 42 on which the first measurement point M1 is set. The second terminal portion 48 is electrically connected to the base end of the second conductive member 44 on which the second measurement point M2 is set. The first terminal portion 46 and the second terminal portion 48 are connected to the power supply unit 26 via lead wires.

[0033] The power supply unit 26 applies a voltage for determining the shape of the shape variable mechanism 12 between the first terminal section 46 and the second terminal section 48 in accordance with the control signal CTL from the control unit 28. As a result, a voltage is applied between the first conductive member 42 and the second conductive member 44, causing current to flow. The control unit 28 can obtain information including voltage values ​​and current values ​​obtained by applying voltage to the first terminal section 46 and the second terminal section 48 via the power supply unit 26, and measure the impedance between the two terminals.

[0034] When the sliding portion 34 is displaced, the distance between the first terminal portion 46 and the second terminal portion 48, in other words, the distance between the first measurement point M1 and the second measurement point M2, changes. In addition, the impedance between the two measurement points changes according to this change in distance. Therefore, the control unit 28 can determine the position of the sliding portion 34 from the measured impedance (absolute value). From the position of the sliding portion 34, the amount of displacement of the displacement transmission member 22, and consequently the shape of the shape variable mechanism 12, can be determined. The control unit 28 determines a shape signal related to the shape taken by the displacement transmission member 22 according to the measured impedance. For example, a conversion table that associates impedance with the shape of the shape variable mechanism 12 is created in advance and held in the shape recognition support unit 40. The control unit 28 uses this conversion table to determine the shape taken by the shape variable mechanism 12 from the measured impedance. The control unit 28 then outputs a shape signal indicating the determined shape to the display unit 30.

[0035] The display unit 30 displays information regarding the shape of the shape-variable mechanism 12 to the outside. The manner in which the information is displayed by the display unit 30 is not particularly limited; the shape taken by the shape-variable mechanism 12 may be illustrated or described in words. This allows the user of the catheter system 1 to understand the shape taken by the shape-variable mechanism 12. The control unit 28 may also output a signal indicating the impedance value as a shape signal to the display unit 30. In this case, the user of the catheter system 1 can understand the shape taken by the shape-variable mechanism 12 from the impedance displayed on the monitor. Therefore, the user can receive support from the shape recognition support unit 40 in understanding the shape taken by the shape-variable mechanism 12. The execution of the shape recognition support process may be started by an instruction from the user via the input unit 24, or it may be started automatically by an operating program held in the shape recognition support unit 40.

[0036] As described above, the catheter system 1 according to this embodiment includes a shape recognition support unit 40 that outputs a shape signal related to the shape change mechanism 12. The shape recognition support unit 40 uses a first conductive member 42 that follows the displacement of the slide portion 34 as the first measurement point M1, and a second conductive member 44 that does not follow the displacement of the slide portion 34 as the second measurement point M2, connects a first terminal portion 46 and a second terminal portion 48 to each measurement point, and measures the impedance by applying a voltage to the two terminal portions. Then, by utilizing the fact that the impedance between the two measurement points changes due to the displacement of the slide portion 34, it presents information regarding the shape change mechanism 12. This makes it easier for people other than the operator of the catheter 4 to understand the shape change mechanism 12. In addition, it becomes easier for the operator of the catheter 4 to quickly and accurately understand the shape change mechanism 12.

[0037] (Embodiment 2) Embodiment 2 has the same configuration as Embodiment 1, except for the configuration related to shape grasping support. Hereinafter, this embodiment will be described mainly for the configuration that differs from Embodiment 1, and the common configuration will be briefly described or omitted. Figure 6 is a diagram showing the internal structure of the handle 14 and the shape grasping support unit 40 according to Embodiment 2.

[0038] In the catheter 4 of this embodiment, a first measurement point M1 is set on the first conductive member 42, a second measurement point M2 is set on one end of the second conductive member 44, and a third measurement point M3 is set on the other end of the second conductive member 44. As an example, the second measurement point M2 is set on the base end of the second conductive member 44, and the third measurement point M3 is set on the tip end of the second conductive member 44. Therefore, the first measurement point M1 is positioned between the second measurement point M2 and the third measurement point M3. The shape-grasping support unit 40 has a first terminal portion 46 electrically connected to the first conductive member 42 on which the first measurement point M1 is set, a second terminal portion 48 electrically connected to the base end of the second conductive member 44 on which the second measurement point M2 is set, and a third terminal portion 50 electrically connected to the tip end of the second conductive member 44 on which the third measurement point M3 is set. The first terminal portion 46, the second terminal portion 48, and the third terminal portion 50 are connected to the power supply unit 26 via lead wires.

[0039] The power supply unit 26 applies a voltage between the first terminal 46 and the second terminal 48. The power supply unit 26 also applies a voltage between the first terminal 46 and the third terminal 50. The control unit 28 obtains information including voltage values ​​and current values ​​obtained by applying voltage to the first terminal 46 and the second terminal 48 via the power supply unit 26 and measures the first impedance between the two terminals. The control unit 28 also obtains information including voltage values ​​and current values ​​obtained by applying voltage to the first terminal 46 and the third terminal 50 via the power supply unit 26 and measures the second impedance between the two terminals.

[0040] For example, when the slide portion 34 is displaced toward the proximal end of the catheter 4, the distance between the first terminal portion 46 and the second terminal portion 48 decreases, and the distance between the first terminal portion 46 and the third terminal portion 50 increases. As a result, both the first impedance between the first terminal portion 46 and the second terminal portion 48 and the second impedance between the first terminal portion 46 and the third terminal portion 50 change. Therefore, the control unit 28 can determine the position of the slide portion 34 from the difference or ratio of the measured first impedance (absolute value) and second impedance (absolute value), and can determine the shape of the shape-changing mechanism 12. Accordingly, the control unit 28 determines the shape signal according to the difference between the first impedance and the second impedance, or the ratio of the first impedance and the second impedance. For example, a conversion table is created in advance and stored in the shape-recognition support unit 40, which associates the difference or ratio of the first impedance and the second impedance with the shape of the shape-changing mechanism 12. The control unit 28 uses this conversion table to determine the shape that the shape-changing mechanism 12 will take and outputs the shape signal to the display unit 30.

[0041] In this embodiment, three measurement points are set on the catheter 4, and two impedances are measured. These two impedances increase or decrease in inverse relation to the displacement of the slide portion 34. Therefore, the difference or ratio of these two impedances reflects the displacement of the slide portion 34 more significantly than if only one of the impedances were measured. Thus, by using this difference or ratio to determine the shape taken by the shape-changing mechanism 12, it becomes possible to more accurately grasp the shape taken by the shape-changing mechanism 12.

[0042] (Embodiment 3) Embodiment 3 has the same configuration as Embodiment 1, except for the configuration related to shape grasping support.Hereafter, this embodiment will be described mainly for the configuration that differs from Embodiment 1, and the common configuration will be briefly described or omitted.Figure 7(A) is a diagram showing the internal structure of the handle 14 and the shape grasping support unit 40 according to Embodiment 3.Figures 7(B) and 7(C) are schematic diagrams illustrating the change in the positional relationship between the two terminal parts and the conductive part 54 and insulating part 56 due to the displacement of the slide part 34.

[0043] The catheter 4 of the present embodiment has a displacement member 52 that is displaced together with the slide portion 34. The displacement member 52 has conductive portions 54 and insulating portions 56 that are arranged in the displacement direction, that is, in the axial direction of the shaft 10. The displacement member 52 of the present embodiment is configured, as an example, by a displacement transmission member 22 connected to the slide portion 34. By making the displacement transmission member 22 also serve as the displacement member 52, an increase in the number of parts can be suppressed. The displacement transmission member 22 is made of a metal such as SUS. Also, a part of the proximal end side of the displacement transmission member 22 is covered with an insulating member such as PEBAX. In the present embodiment, the proximal end side of the displacement transmission member 22 from the position where the slide portion 34 is connected is covered with an insulating member. And the portion where the surface of the displacement transmission member 22 is exposed constitutes the conductive portion 54, and the portion covered with the insulating member constitutes the insulating portion 56. Note that a displacement member 52 may be provided separately from the displacement transmission member 22.

[0044] A first measurement point M1 and a second measurement point M2 are set on the catheter 4. The first measurement point M1 is set in a range where the conductive portion 54 extends regardless of the position of the displacement member 52 on the displacement orbit of the displacement member 52. The second measurement point M2 is set in a range where, on the displacement orbit of the displacement member 52, whether the conductive portion 54 extends or the insulating portion 56 extends switches according to the position of the displacement member 52. For example, the first measurement point M1 is arranged on the distal end side in the groove of the support portion 36, and the second measurement point M2 is arranged on the proximal end side in the groove. Therefore, the slide portion 34 is arranged between the first measurement point M1 and the second measurement point M2.

[0045] The shape-grasping support unit 40 has a first terminal section 46 and a second terminal section 48. The first terminal section 46 is electrically connected to a first measurement point M1. The second terminal section 48 is electrically connected to a second measurement point M2. The first terminal section 46 and the second terminal section 48 are, for example, made of annular metal members, and a displacement member 52 is slidably inserted through each terminal section. Therefore, the first terminal section 46 is always in contact with the conductive section 54, regardless of the position of the displacement member 52, in other words, regardless of the position of the sliding section 34. The second terminal section 48 switches between contacting the conductive section 54 and contacting the insulating section 56 depending on the position of the displacement member 52, in other words, depending on the position of the sliding section 34.

[0046] The power supply unit 26 applies a voltage between the first terminal section 46 and the second terminal section 48. The control unit 28 obtains information, including voltage and current values, obtained by applying voltage to the first terminal section 46 and the second terminal section 48, via the power supply unit 26, and measures the impedance between the two terminals. When the slide section 34 and the displacement member 52 are displaced, the object that the second terminal section 48 contacts switches between the conductive section 54 and the insulating section 56. As a result, the impedance between the two terminal sections changes. Therefore, the control unit 28 can determine the position of the slide section 34 from the measured impedance (absolute value) and determine the shape of the shape variable mechanism 12. The control unit 28 determines a shape signal according to the measured impedance and outputs it to the display unit 30.

[0047] As an example, the first measurement point M1 and the second measurement point M2, or rather the first terminal portion 46 and the second terminal portion 48, are set as follows. That is, when the slide portion 34 is at the tip side and the middle portion of the groove, that is, when the shape variable mechanism 12 takes the folded shape and the first unfolded shape, as shown in FIG. 7(B), the first terminal portion 46 contacts the conductive portion 54, and the second terminal portion 48 contacts the insulating portion 56. On the other hand, when the slide portion 34 is located at the base end side of the groove, that is, when the shape variable mechanism 12 takes the second unfolded shape, both the first terminal portion 46 and the second terminal portion 48 contact the conductive portion 54. In this case, based on the impedance between the two terminals, it is possible to determine whether the shape variable mechanism 12 is in either the folded shape or the first unfolded shape, or in the second unfolded shape.

[0048] In the present embodiment, based on the presence or absence of conduction between the second terminal portion 48 and the displacement member 52, the shape taken by the shape variable mechanism 12 is grasped. For this reason, although it is difficult to finely discriminate the shape taken by the shape variable mechanism 12, simplification of the processing and control related to shape grasping support can be achieved. Further, since the positions of the first terminal portion 46 and the second terminal portion 48 are fixed, simplification of the structure related to shape grasping support can be achieved.

[0049] As described above, the embodiments of the present disclosure have been described in detail. The above-described embodiments are merely specific examples for implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design changes such as component changes, additions, deletions, etc. are possible without departing from the idea of the present disclosure defined in the claims. The new embodiments to which design changes are applied have the effects of the combined embodiments and modifications respectively. In the above-described embodiments, with respect to the content in which such design changes are possible, notations such as "in the present embodiment" and "in the present embodiment" are added for emphasis, but design changes are also allowed for the content without such notations. Any combination of the components included in each embodiment is also effective as an aspect of the present disclosure. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached.

[0050] The configuration of the catheter 4 and the shape recognition support unit 40 can be changed as appropriate. For example, the tip 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 implemented by hardware (circuit) or by software (program). If implemented by 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 on the computer from a network or recording medium.

[0051] Furthermore, the shape and number of splines 16 and electrodes 18 are not limited. Electrodes 18 may not be provided on some splines 16. Also, some electrodes 18 may be used for potential measurement or as spares when the ablation range is wide. Moreover, the shape-variable mechanism 12 does not have to have splines 16. For example, the shape-variable mechanism 12 may be a known ring-shaped catheter in which the ring diameter is variable according to the displacement of the slide portion 34.

[0052] The embodiment may be specified by the items described below. [Item 1] A catheter (4) having a long shaft (10) having a lumen (11), a shape-changing mechanism (12) provided on the tip side of the shaft (10), and a handle (14) provided on the proximal end side of the shaft (10), and a shape-grasping support unit (40) that outputs a shape signal relating to the shape taken by the shape-changing mechanism (12), wherein the handle (14) has a slide part (34) that is operated by an operator, and the catheter (4) has a displacement transmission member (22) that is disposed in the lumen (11) and connected to the slide part (34) and the shape-changing mechanism (12), and displaces together with the slide part (34) to deform the shape-changing mechanism (12), The shape-finding support unit (40) has at least two terminals (46, 48) electrically connected to at least two measurement points (M1, M2) where the impedance between measurement points changes due to the displacement of the slide part (34), and measures the impedance by applying a voltage between each terminal (46, 48), and determines a shape signal by utilizing the fact that the impedance changes due to the displacement of the slide part (34), in the catheter system (1).[Second item] The handle (14) has a support portion (36) that slidably supports the slide portion (34), a first conductive member (42) provided on the slide portion (34), and a second conductive member (44) provided on the support portion (36) and extending in the sliding direction of the slide portion (34), the slide portion (34) slides with the first conductive member (42) electrically connected to the second conductive member (44), a first measurement point (M1) is set on the first conductive member (42) and a second measurement point (M2) is set on one end of the second conductive member (44), the shape grasping support unit (40) has a first terminal portion (46) electrically connected to the first measurement point (M1) and a second terminal portion (48) electrically connected to the second measurement point (M2), and measures the impedance by applying a voltage between the first terminal portion (46) and the second terminal portion (48) and determines a shape signal according to the impedance. Catheter system (1) of item 1 [Item 3] A third measurement point (M3) is set on the other end of the second conductive member (44), and the shape grasping support unit (40) has a third terminal (50) electrically connected to the third measurement point (M3), and measures the first impedance by applying a voltage between the first terminal (46) and the second terminal (48), measures the second impedance by applying a voltage between the first terminal (46) and the third terminal (50), and determines the shape signal according to the difference or ratio of the first impedance and the second impedance, Catheter system (1) of item 2.[Item 4] The catheter system (1) of Item 1, wherein the catheter (4) has a displacement member (52) that displaces together with the slide portion (34), the displacement member (52) has a conductive portion (54) and an insulating portion (56) that are aligned with each other in the direction of displacement, the catheter (4) has a first measurement point (M1) set in the range on the displacement trajectory of the displacement member (52) in which the conductive portion (54) extends regardless of the position of the displacement member (52), and a second measurement point (M2) set in the range in which the extension of the conductive portion (54) or the insulating portion (56) switches depending on the position of the displacement member (52), the shape grasping support unit (40) has a first terminal portion (46) electrically connected to the first measurement point (M1), and a second terminal portion (48) electrically connected to the second measurement point (M2), and a voltage is applied between the first terminal portion (46) and the second terminal portion (48) to measure the impedance and determine the shape signal according to the impedance. [Item 5] The catheter system according to claim 4, wherein the displacement member (52) is composed of a displacement transmission member (22). [Item 6] The catheter system (1) according to any one of items 1 to 5, wherein the shape-changing mechanism (12) has a plurality of splines (16) arranged in the direction of the axis of the shaft (10) and at least one electrode (18) provided on each spline (16), and the shape-changing mechanism (12) can switch between at least a first unfolded shape in which the plurality of splines (16) are curved to a predetermined degree and a second unfolded shape in which the plurality of splines (16) are curved more sharply than in the first unfolded shape by the displacement of the sliding part (34).[Item 7] A shape recognition support method for a catheter (4) having a long shaft (10) having a lumen (11), a shape-changing mechanism (12) provided on the tip side of the shaft (10), and a handle (14) provided on the proximal end side of the shaft (10), wherein the handle (14) has a slide portion (34) operated by an operator, and the catheter (4) has a displacement transmission member (22) disposed in the lumen (11) and connected to the slide portion (34) and the shape-changing mechanism (12), which displaces together with the slide portion (34) to deform the shape-changing mechanism (12), and the shape recognition support method includes applying a voltage between at least two measurement points (M1, M2) where the impedance between measurement points changes due to the displacement of the slide portion (34) to measure the impedance, and using the fact that the impedance changes due to the displacement of the slide portion (34) to present shape information regarding the state taken by the shape-changing mechanism (12).

[0053] This disclosure can be used in catheter systems and shape recognition support methods.

[0054] 1 Catheter system, 4 Catheter, 10 Shaft, 12 Shape-changing mechanism, 14 Handle, 22 Displacement transmission member, 34 Slide part, 36 Support part, 40 Shape-grasping support part, 42 First conductive member, 44 Second conductive member, 46 First terminal part, 48 Second terminal part, 50 Third terminal part, 52 Displacement member, 54 Conductive part, 56 Insulating part, M1 First measurement point, M2 Second measurement point, M3 Third measurement point.

Claims

1. A catheter system comprising: a catheter having a long shaft having a lumen, a shape-changing mechanism provided at the tip of the shaft, and a handle provided at the proximal end of the shaft; and a shape-grasping support unit that outputs a shape signal relating to the shape taken by the shape-changing mechanism, wherein the handle has a slide portion operated by an operator; the catheter has a displacement transmission member disposed within the lumen and connected to the slide portion and the shape-changing mechanism, which displaces together with the slide portion to deform the shape-changing mechanism; and the shape-grasping support unit has at least two terminal portions electrically connected to at least two measurement points where the impedance between measurement points changes due to the displacement of the slide portion, and the impedance is measured by applying a voltage between each terminal portion, and the shape signal is determined by utilizing the fact that the impedance changes due to the displacement of the slide portion.

2. The catheter system according to claim 1, wherein the handle has a support portion that slidably supports the slide portion, a first conductive member provided on the slide portion, and a second conductive member provided on the support portion and extending in the sliding direction of the slide portion, the slide portion slides with the first conductive member electrically connected to the second conductive member, a first measurement point is set on the first conductive member, and a second measurement point is set on one end of the second conductive member, and the shape grasping support portion has a first terminal portion electrically connected to the first measurement point and a second terminal portion electrically connected to the second measurement point, and a voltage is applied between the first terminal portion and the second terminal portion to measure the impedance, and the shape signal is determined according to the impedance.

3. A catheter system according to claim 2, wherein a third measurement point is set on the other end of the second conductive member, the shape-grasping support unit has a third terminal portion electrically connected to the third measurement point, a voltage is applied between the first terminal portion and the second terminal portion to measure a first impedance, a voltage is applied between the first terminal portion and the third terminal portion to measure a second impedance, and the shape signal is determined according to the difference or ratio of the first impedance and the second impedance.

4. The catheter system according to claim 1, wherein the catheter has a displacement member that displaces together with the sliding portion, the displacement member has a conductive portion and an insulating portion that are aligned with each other in the direction of displacement, the catheter has a first measurement point set on the displacement trajectory of the displacement member in a range in which the conductive portion extends regardless of the position of the displacement member, and a second measurement point set in a range in which the extension of the conductive portion or the insulating portion switches depending on the position of the displacement member, the shape grasping support unit has a first terminal portion electrically connected to the first measurement point and a second terminal portion electrically connected to the second measurement point, and the impedance is measured by applying a voltage between the first terminal portion and the second terminal portion, and the shape signal is determined according to the impedance.

5. The catheter system according to claim 4, wherein the displacement member is composed of the displacement transmission member.

6. The catheter system according to any one of claims 1 to 5, wherein the shape-changing mechanism comprises a plurality of splines arranged in the direction of the axis of the shaft and at least one electrode provided on each spline, and the shape-changing mechanism is capable of switching between at least a first unfolded shape in which the plurality of splines are curved to a predetermined degree and a second unfolded shape in which the plurality of splines are more curved than in the first unfolded shape by displacement of the sliding part.

7. A shape recognition support method for a catheter having a long shaft having a lumen, a shape-changing mechanism provided on the tip side of the shaft, and a handle provided on the proximal end side of the shaft, wherein the handle has a sliding portion operated by an operator, the catheter has a displacement transmission member disposed in the lumen and connected to the sliding portion and the shape-changing mechanism, which displaces together with the sliding portion to deform the shape-changing mechanism, and the shape recognition support method includes measuring the impedance by applying a voltage between at least two measurement points where the impedance between measurement points changes due to the displacement of the sliding portion, and presenting shape information relating to the state taken by the shape-changing mechanism by utilizing the fact that the impedance changes due to the displacement of the sliding portion.

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