Balloon-type electrode catheter and method of operating a balloon-type electrode catheter

Abstract

This disclosure provides a technique for suppressing the displacement of an electrode disposed in a catheter. A balloon-type electrode catheter comprises: a catheter shaft (2) having an outer shaft (8) and an inner shaft (10), a balloon (4) disposed on the tip side of the catheter shaft (2), and an electrode (46). The balloon (4) comprises: an outer junction (24), an inner junction (32), a tip-side large-diameter portion (34), a base-side large-diameter portion (36), a small-diameter portion (38) located between the two large-diameter portions and having a diameter smaller than the diameters of the two large-diameter portions, a tip-side inclined portion (40) connecting the tip-side large-diameter portion (34) and the small-diameter portion (38), and a base-side inclined portion (42) connecting the base-side large-diameter portion (36) and the small-diameter portion (38). The electrode (46) is exposed at least in the small-diameter portion (38). After inflation, the balloon (4) deforms by the relative displacement of the outer shaft (8) and the inner shaft (10) in a manner that brings the two inclined portions closer together.

Description

Technical Field

[0001] This disclosure relates to a balloon-type electrode catheter and a method for operating the balloon-type electrode catheter. Background Technology

[0002] Patients with heart failure, pulmonary hypertension, etc., sometimes experience elevated atrial blood pressure. As a treatment method to suppress this rise in atrial pressure, shunt surgery is known to involve forming a shunt (through-hole) in the atrial septum, which serves as a release channel for atrial pressure. During shunt surgery, the periphery of the through-hole is sometimes thermally ablated using an ablation catheter with an electrode at its tip, in a manner that maintains the through-hole for a predetermined period of time (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-60825 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] When thermal ablation is performed on the periphery of the shunt using the aforementioned ablation conduit, it is ideal to maintain the position of the electrode during ablation in order to perform thermal ablation on the periphery more reliably.

[0008] This disclosure was made in view of the following circumstances, and its purpose is to provide a technique for suppressing the displacement of electrodes disposed in a catheter.

[0009] Technical solution

[0010] One aspect of this disclosure is a balloon-type electrode catheter. This balloon-type electrode catheter comprises: a catheter shaft having a tubular outer shaft and an inner shaft accommodated within the outer shaft in a state where it can be relatively displaced relative to the outer shaft in the axial direction, the catheter shaft being inserted into the body; a balloon disposed at the tip of the catheter shaft, capable of expansion by fluid supplied from the base of the catheter shaft; and an electrode disposed on the surface of the balloon. The balloon has: an outer engagement portion engaging with the outer shaft, and an inner engagement portion engaging with the inner shaft at a position offset axially from the outer engagement portion. In its expanded state, the balloon has: a tip-side large-diameter portion, a base-side large-diameter portion located at the base of the catheter shaft, closer to the tip-side large-diameter portion than the tip-side large-diameter portion, a small-diameter portion located between the tip-side and base-side large-diameter portions and having a diameter smaller than the diameters of the two large-diameter portions, a tip-side inclined portion connecting the tip-side large-diameter portion and the small-diameter portion, and a base-side inclined portion connecting the base-side large-diameter portion and the small-diameter portion. The electrode is exposed at least in the small-diameter portion. After the balloon expands by the inflow of fluid, it deforms by the relative displacement of the outer axis and the inner axis, so that the tip side tilted portion approaches the base side tilted portion.

[0011] Another aspect of this disclosure is a method of operating a balloon-type electrode catheter, which has a balloon with electrodes on the tip side of the catheter shaft. The method of operating the balloon-type electrode catheter includes: allowing fluid to flow into the balloon to cause it to expand in a dumbbell shape, deforming the balloon such that the tip and base of the balloon approach each other along the axial direction of the catheter shaft, and applying current to the electrodes.

[0012] Any combination of the above-mentioned constituent elements, or any transformation of the expression of this disclosure among methods, apparatuses, systems, etc., is also valid as a solution of this disclosure.

[0013] Beneficial effects

[0014] According to this disclosure, it is possible to suppress the displacement of electrodes disposed in the catheter. Attached Figure Description

[0015] Figure 1 This is a top view of the balloon-type electrode catheter of the embodiment.

[0016] Figure 2 This is a magnified three-dimensional view of the tip of the balloon-type electrode catheter.

[0017] Figure 3 This is an enlarged cross-sectional view of the tip side of the balloon-type electrode catheter.

[0018] Figure 4 This is an enlarged cross-sectional view of the tip side of the balloon-type electrode catheter.

[0019] Figure 5 This is an enlarged side view of the tip of the balloon-type electrode catheter.

[0020] Figure 6 (A) is an enlarged three-dimensional view of the tip side of the balloon-type electrode catheter. Figure 6 (B) is a schematic cross-sectional view of the top side of the balloon-type electrode catheter.

[0021] Figure 7 (A) is an enlarged three-dimensional view of the base side of the balloon-type electrode catheter. Figure 7 (B) is an enlarged cross-sectional view of the base side of the balloon-type electrode catheter.

[0022] Figure 8 (A) Figure 8 (B) and Figure 8 (C) is a diagram illustrating the working method of the balloon-type electrode catheter.

[0023] Figure 9 This is a diagram illustrating the working method of a balloon-type electrode catheter. Detailed Implementation

[0024] Hereinafter, the present disclosure will be described based on preferred embodiments with reference to the accompanying drawings. These embodiments are not intended to limit the scope of the present disclosure but are examples, and all features described in the embodiments, and combinations thereof, are not necessarily essential features of the present disclosure. Identical or equivalent constituent elements, components, and processes shown in the various drawings are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. Furthermore, for ease of explanation, the scales and shapes of the parts shown in the figures are set in a convenient manner and are not to be interpreted limitingly unless specifically mentioned. In addition, when terms such as "first" and "second" are used in this specification or claims, unless specifically mentioned, these terms are used to distinguish one component from others and do not indicate any order or importance. Furthermore, in each drawing, based on the description of the embodiments, parts of less important components are omitted.

[0025] Figure 1 This is a top view of the balloon-type electrode catheter 1 according to the embodiment. The balloon-type electrode catheter 1 includes a catheter shaft 2, a balloon 4, and a handle 6. The catheter shaft 2 is an elongated tubular member. The length of the catheter shaft 2 is, for example, 600 mm to 1800 mm. The balloon 4 is located on the distal end (distal end) side of the catheter shaft 2. The handle 6 is located on the proximal end (base end) side of the catheter shaft 2. Hereinafter, the side of the balloon-type electrode catheter 1 or the catheter shaft 2 with the balloon 4 will be referred to as the "proximal end side" only, and the side with the handle 6 will be referred to as the "base end side" only. The catheter shaft 2 is inserted into the body from the distal end side. Thus, the balloon 4 is inserted into the body. The handle 6 is positioned externally for operation by the surgeon.

[0026] Figure 2 This is an enlarged three-dimensional view of the tip of balloon-type electrode catheter 1. Figure 3 This is an enlarged cross-sectional view of the tip side of the balloon-type electrode catheter 1. Figure 4 This is an enlarged cross-sectional view of the tip side of the balloon-type electrode catheter 1. Figures 2-4 The diagram shows the inflated state of balloon 4. Additionally, for clarity, some components have been omitted from the diagrams.

[0027] like Figure 2 and Figure 3 As shown, the conduit shaft 2 has an outer shaft 8 and an inner shaft 10. The outer shaft 8 and the inner shaft 10 are made of known flexible materials such as resins such as polyolefins and polyamides. The outer shaft 8 is tubular and houses the inner shaft 10 inside. The inner shaft 10 is housed within the outer shaft 8 in a state where it can be relatively displaced relative to the outer shaft 8 in the axial direction.

[0028] The outer shaft 8 of this embodiment has a multi-cavity structure. Specifically, the outer shaft 8 has: a main cavity 12 extending along a region coinciding with the central axis of the outer shaft 8; and a plurality of secondary cavities 14 disposed around the main cavity 12. The main cavity 12 and each secondary cavity 14 extend from the top end side to the base end side of the outer shaft 8. The inner shaft 10 is housed in the main cavity 12. A portion of the plurality of secondary cavities 14 constitutes a supply cavity 14a, another portion constitutes a discharge cavity 14b, another portion constitutes a wire cavity 14c, and another portion constitutes a sensor cavity 14d. The function of each secondary cavity 14 will be described in detail below.

[0029] The tip of the inner shaft 10, located on the side closer to the tip of the balloon 4, protrudes from the outer shaft 8. A cap-shaped tip 16 covers this tip. The tip 16, like the conduit shaft 2, is made of a known resin material. As an example, the tip 16 and the inner shaft 10 are joined together by welding. A connecting member 18 is embedded in a portion of the outer peripheral surface of the tip 16. As an example, the connecting member 18 is annular and made of a metallic material such as platinum or iridium. Therefore, the connecting member 18 is conductive. The tip 16 and the connecting member 18 are positioned on the side closer to the tip of the balloon 4.

[0030] like Figure 4 As shown, a groove 16a extending from the base of the tip 16 toward the tip side is provided on the inner circumferential surface of the tip 16. Furthermore, a through hole 16b for a wire extending from the tip of the groove 16a toward the connecting member 18 is provided on the tip 16. The balloon-type electrode catheter 1 includes a wire 20 extending from the base side of the catheter shaft 2 toward the tip side. The wire 20 passes through the wire cavity 14c from the base side of the catheter shaft 2 to the tip 16. The wire 20 reaching the tip 16 passes through the groove 16a and the through hole 16b, and is electrically connected to the connecting member 18. As an example, the connecting member 18 and the wire 20 are joined together by welding. The opening of the groove 16a facing the balloon 4 is sealed with adhesive or the like. The base side of the wire 20 is connected to an external power supply device via a handle 6.

[0031] The inner shaft 10 of this embodiment has a single-cavity structure. The inner shaft 10 has a wire cavity 22 extending along a region coinciding with the central axis of the inner shaft 10. The tip 16 has a wire through-hole 16c at a position coinciding with the wire cavity 22 in the axial direction of the guide shaft 2. A guide wire GW (see reference) passes through the wire cavity 22 and the wire through-hole 16c. Figure 8 (A, etc.).

[0032] The balloon 4 can be expanded by fluid supplied from the base of the catheter shaft 2. The fluid is, for example, physiological saline. The balloon 4 is made of a known flexible material containing resins such as polyolefins or polyamides. Figure 2 and Figure 3As shown, the balloon 4 has, in sequence from the base end side of the catheter shaft 2, an outer joint 24, a base end side expansion 26, a diameter reduction 28, a tip side expansion 30, and an inner joint 32.

[0033] The outer joint portion 24 is a cylindrical shape with approximately the same diameter as the outer shaft 8, covering the outer peripheral surface of the region of the outer shaft 8 adjacent to the balloon 4. As an example, the outer joint portion 24 and the outer shaft 8 are joined together by welding. Thus, one end of the balloon 4 is joined to the outer shaft 8. It should be noted that in this embodiment, the outer peripheral surface of the region of the outer shaft 8 adjacent to the balloon 4 is thinned by the same amount as the thickness of the outer joint portion 24. Therefore, when this region is joined to the outer joint portion 24, the outer peripheral surface of the outer joint portion 24 is flush with the outer peripheral surface of the outer shaft 8.

[0034] The inner joint 32 is a cylindrical portion with approximately the same diameter as the tip 16, covering the outer peripheral surface of the tip 16 that is closer to the base end of the connecting member 18. As an example, the inner joint 32 and the tip 16 are joined together by welding. Thus, the other end of the balloon 4 is joined to the inner shaft 10 at a position offset axially from the joint between the balloon 4 and the outer shaft 8 (outer joint 24). It should be noted that in this embodiment, with the tip 16 joined to the inner joint 32, the outer peripheral surface of the inner joint 32 is flush with the outer peripheral surface of the connecting member 18.

[0035] The basal-side expansion portion 26 extends between the outer junction 24 and the narrowed portion 28, including the portion of the balloon 4 with the maximum diameter. The apical-side expansion portion 30 extends between the inner junction 32 and the narrowed portion 28, including the portion of the balloon 4 with the maximum diameter. The narrowed portion 28 is a radially concave portion that covers the entire circumferential region (the direction around the axis of the catheter axis 2) of the balloon 4 between the basal-side expansion portion 26 and the apical-side expansion portion 30. The inflated balloon 4 becomes dumbbell-shaped through the basal-side expansion portion 26, the narrowed portion 28, and the apical-side expansion portion 30.

[0036] In its inflated state, the balloon 4 has a large-diameter portion 34 at the tip, a large-diameter portion 36 at the base, and a small-diameter portion 38. The large-diameter portion 36 at the base is located on the basal side of the catheter axis 2, closer to the tip than the large-diameter portion 34 at the tip. The small-diameter portion 38 is located between the large-diameter portions 34 at the tip and 36 at the base. The diameters of the large-diameter portions 34 at the tip and 36 at the base are larger than the diameter of the small-diameter portion 38, and the diameter of the small-diameter portion 38 is smaller than the diameters of the two large-diameter portions. For example, the diameters of the large-diameter portions 34 at the tip and 36 at the base are 9 mm to 15 mm, and the diameter of the small-diameter portion 38 is 6 mm to 12 mm.

[0037] Furthermore, the balloon 4 has a tip-side inclined portion 40 and a base-side inclined portion 42. The tip-side inclined portion 40 is the portion connecting the tip-side large-diameter portion 34 and the tip-side small-diameter portion 38, and is inclined in a manner from the tip-side large-diameter portion 34 toward the tip-side small-diameter portion 38 and close to the catheter axis 2. The base-side inclined portion 42 is the portion connecting the base-side large-diameter portion 36 and the base-side small-diameter portion 38, and is inclined in a manner from the base-side large-diameter portion 36 toward the base-side small-diameter portion 38 and close to the catheter axis 2.

[0038] In the balloon 4 of this embodiment, the large-diameter portion 34 on the apex side is disposed in the apex-side expansion portion 30, the large-diameter portion 36 on the base side is disposed in the base-side expansion portion 26, and the small-diameter portion 38, the apex-side inclined portion 40, and the base-side inclined portion 42 are disposed in the narrowed-diameter portion 28. As an example, the large-diameter portion 34 on the apex side and the large-diameter portion 36 on the base side are the portions with the largest diameter in the balloon 4. Furthermore, the small-diameter portion 38 is the portion with the smallest diameter in the narrowed-diameter portion 28. It should be noted that the base-side expansion portion 26 and the apex-side expansion portion 30 have shapes that are reversed relative to each other with the narrowed-diameter portion 28 as an axis, but the shapes of the two expansion portions are not limited to this. For example, it is also possible that only one of the expansion portions includes the portion with the largest diameter of the balloon 4. In addition, the diameters of the large-diameter portion 34 on the apex side and the large-diameter portion 36 on the base side may be different.

[0039] Inside the balloon 4, a supply chamber 14a and a discharge chamber 14b are connected to an outer shaft 8. The supply chamber 14a is a cavity that allows fluid to flow into the balloon 4. The supply chamber 14a has a supply port 14a1 inside the balloon 4 to allow fluid to flow into the balloon 4. The base of the supply chamber 14a is connected to an external fluid supply and discharge device via a handle 6. Fluid supplied from the fluid supply and discharge device passes through the supply chamber 14a and is discharged into the balloon 4 from the supply port 14a1. This allows the balloon 4 to inflate.

[0040] The discharge chamber 14b is a chamber for venting gas from inside the balloon 4. The discharge chamber 14b has an outlet 14b1 within the balloon 4 for gas to flow out of the balloon 4. The base of the discharge chamber 14b is connected to the outside via a handle 6. For example, the discharge chamber 14b is used during venting procedures before using the balloon-type electrode catheter 1. That is, fluid is supplied to the balloon 4 from the fluid supply and discharge device via the supply chamber 14a. The fluid supplied to the balloon 4, along with the gas inside the balloon 4, flows from the outlet 14b1 into the discharge chamber 14b, and is then discharged to the outside via the discharge chamber 14b. It should be noted that not only the gas inside the balloon 4 can be discharged to the outside, but the gas in the supply chamber 14a can also be discharged to the outside. When the balloon 4 is contracted during the use of the balloon-type electrode catheter 1, fluid is discharged from the balloon 4 via the supply chamber 14a.

[0041] In this embodiment, the supply port 14a1 is located closer to the tip of the catheter shaft 2 than the discharge port 14b1. This allows fluid to flow into the balloon 4 from the side closer to the tip of the catheter shaft 2, and gas to be discharged from the side closer to the base of the catheter shaft 2. Therefore, more reliable venting is possible. In this embodiment, a portion of the circumferential direction of the tip of the outer shaft 8 within the balloon 4 is cut. Specifically, the portion extending from the discharge chamber 14b at the tip is cut. The remaining portion of the supply chamber 14a extends from the tip. As a result, the supply port 14a1 is offset towards the tip of the catheter shaft 2 compared to the discharge port 14b1.

[0042] The tip of the outer shaft 8 is incised, thereby exposing a portion of the inner shaft 10 within the balloon 4. Within the exposed portion of the inner shaft 10, a contrast marker 44 is positioned at a location coinciding with the small-diameter portion 38 when viewed radially from the balloon 4 (in a direction orthogonal to the axis of the catheter shaft 2). The surgeon can use the contrast marker 44 as an indicator to determine the position of the balloon 4 and even the small-diameter portion 38.

[0043] like Figure 3 and Figure 4 As shown, the balloon-type electrode catheter 1 includes an electrode 46 disposed on the surface of a balloon 4. In this embodiment, the electrode 46 is composed of a metal film laminated on the surface of the balloon 4. In this case, conductive ink containing the metal constituting the electrode 46 is applied to the surface of the balloon 4, thereby forming the electrode 46.

[0044] Electrode 46 extends from connecting member 18 through tip-side inclined portion 40 to small-diameter portion 38. Furthermore, end portion 46a of electrode 46 is positioned closer to the base end than the small-diameter portion 38. In this embodiment, end portion 46a is positioned at the base-side inclined portion 42. Therefore, electrode 46 extends over the inner joint portion 32, tip-side expansion portion 30, and reduced-diameter portion 28 of balloon 4. The tip end of the catheter shaft 2 of electrode 46 is connected to connecting member 18. Thus, wire 20 is electrically connected to electrode 46 via connecting member 18. In this embodiment, the connecting member 18 side of electrode 46 is a cylindrical shape with approximately the same diameter as the inner joint portion 32. Furthermore, multiple strip-shaped portions extend radially from the ends of the cylindrical portions at the tip-side expansion portion 30. And the end portion 46a of each strip-shaped portion is located at the base-side inclined portion 42.

[0045] Figure 5This is an enlarged side view of the tip side of the balloon-type electrode catheter 1. The balloon-type electrode catheter 1 has an insulating film 48. The insulating film 48 covers at least a portion of the region of the electrode 46 from the connecting member 18 to the tip-side inclined portion 40. The electrode 46 is exposed at least in the small-diameter portion 38 and is not covered by the insulating film 48. As an example, the insulating film 48 can be formed by applying a coating containing a known insulating material to the surface of the electrode 46. In this embodiment, the insulating film 48 extends throughout the entire inner joint portion 32 of the balloon 4, the entire tip-side expansion portion 30, and a portion of the tip-side inclined portion 40. Therefore, the electrode 46 is exposed in the remaining portion of the tip-side inclined portion 40, the small-diameter portion 38, and the base-side inclined portion 42. The width W1 of the exposed portion of the electrode 46 in the axial direction of the catheter shaft 2, in other words, the width W1 from the base-side end of the insulating film 48 to the end 46a of the electrode 46, is, for example, 1.5 mm to 4.5 mm.

[0046] Furthermore, the balloon 4 has a through hole 50. The through hole 50 is a hole connecting the inside and outside of the balloon 4, used to drain fluid from inside the balloon 4 to the outside. The through hole 50 can be formed by irradiating the balloon 4 with a laser or the like. The through hole 50 is disposed in at least one of the tip-side inclined portion 40 and the base-side inclined portion 42. Preferably, the through hole 50 is disposed in at least the tip-side inclined portion 40. More preferably, the through hole 50 is disposed in both the tip-side inclined portion 40 and the base-side inclined portion 42. In this embodiment, a plurality of through holes 50 are provided in the tip-side inclined portion 40 and the base-side inclined portion 42, respectively.

[0047] Along the axial direction of the catheter shaft 2, a through hole 50 disposed on the tip-side inclined portion 40 is located at a distance W2 relative to the exposed portion of the electrode 46. Furthermore, a through hole 50 disposed on the base-side inclined portion 42 is located at a distance W3 relative to the exposed portion of the electrode 46. The distances W2 and W3 are, for example, 0.5 mm to 1.5 mm. It should be noted that the distances W2 and W3 can be the same or different values. In each inclined portion, multiple through holes 50 are arranged at predetermined intervals in the circumferential direction of the balloon 4. As an example, multiple through holes 50 are arranged at 45° intervals in the circumferential direction. Furthermore, the through holes 50 are configured to avoid the electrode 46, that is, not to coincide with the electrode 46.

[0048] Figure 6 (A) is an enlarged perspective view of the tip side of the balloon-type electrode catheter 1. Figure 6 Figure (B) is a schematic cross-sectional view of the tip of the balloon-type electrode catheter 1. For ease of explanation, some components have been omitted from the figures. Figure 6 (A) and Figure 6As shown in (B), the outer shaft 8 has a sensor through hole 52 on the side closer to the base end of the balloon 4, which connects the inside and outside of the sensor cavity 14d. As an example, the sensor through hole 52 is provided at a position that coincides with the outer joint portion 24.

[0049] The balloon-type electrode catheter 1 has a temperature sensor 54 for measuring the temperature of the electrode 46. The temperature sensor 54 is, for example, a thermocouple. The temperature sensor 54 extends from the base end of the catheter shaft 2 through the sensor cavity 14d to the sensor through hole 52. Then, the temperature sensor 54 extends through the sensor through hole 52 to the outer joint 24. The balloon 4 has a two-layer structure, and the temperature sensor 54 extends through the interlayer of the balloon 4 to a position where the temperature of the electrode 46 can be measured. The opening of the sensor cavity 14d facing into the balloon 4 is sealed with an adhesive or the like. The base end of the temperature sensor 54 is connected to an external control device via a handle 6.

[0050] Figure 7 (A) is an enlarged three-dimensional view of the base side of the balloon-type electrode catheter 1. Figure 7 (B) is an enlarged cross-sectional view of the base end of the balloon-type electrode catheter 1. The handle 6 has a hub 56, a fluid port 58, an air port 60, a connector 62, and a guidewire port 64. The hub 56 is connected to the base end of the catheter shaft 2. Within the hub 56, the supply chamber 14a, the discharge chamber 14b, the wire chamber 14c, and the sensor chamber 14d are separated from each other.

[0051] The fluid port 58 is connected to the hub portion 56 via the first protective tube 66. One end of the first protective tube 66 is connected to the fluid port 58, and the other end is connected to the hub portion 56. The supply chamber 14a inside the hub portion 56 is inserted into the first protective tube 66. Thus, the supply chamber 14a is connected to the fluid port 58 via the first protective tube 66. The connection between the first protective tube 66 and the supply chamber 14a is sealed by a resin mold or the like.

[0052] Air port 60 is connected to hub portion 56 via second protective tube 68. One end of second protective tube 68 is connected to air port 60, and the other end is connected to hub portion 56. Exhaust chamber 14b inside hub portion 56 is inserted into second protective tube 68. Thus, exhaust chamber 14b is connected to air port 60 via second protective tube 68. The connection between second protective tube 68 and exhaust chamber 14b is sealed by resin casting or the like.

[0053] Connector 62 is connected to hub portion 56 via third protective tube 70. Connector 62 is attached to one end of third protective tube 70, and hub portion 56 is connected to the other end. Wire 20 extending from wire cavity 14c and temperature sensor 54 extending from sensor cavity 14d within hub portion 56 are inserted into third protective tube 70 and connected to terminals built into connector 62. The connection between third protective tube 70 and wire cavity 14c and sensor cavity 14d is sealed using resin molding or the like.

[0054] The guide wire port 64 is connected to the base end of the inner shaft 10 protruding from the hub portion 56. A cylindrical chuck member 72 is fixed to the outlet of the inner shaft 10 in the hub portion 56. An operating ring 74 is fitted onto the chuck member 72. Threaded grooves are provided on the outer circumferential surface of the chuck member 72 and the inner circumferential surface of the operating ring 74, and the operating ring 74 is screwed onto the chuck member 72. The operating ring 74 can approach and separate from the hub portion 56 by its own rotation. A support cylinder 76 supporting the inner shaft 10 is provided between the operating ring 74 and the guide wire port 64. The support cylinder 76 has a through hole extending axially along the inner shaft 10, through which the inner shaft 10 is inserted. The support cylinder 76 and the inner shaft 10 are engaged with each other.

[0055] The inner shaft 10 is not fixed to the hub portion 56, the chuck member 72, or the operating ring 74, and can be displaced relative to them. On the other hand, the outer shaft 8 is fixed to the hub portion 56 via a connection between the first protective tube 66 and the supply chamber 14a, and a connection between the second protective tube 68 and the discharge chamber 14b. When the operating ring 74 is displaced away from the hub portion 56, the support cylinder 76 is pressed towards the base end by the operating ring 74. As a result, the inner shaft 10 and the support cylinder 76 are displaced together in the direction in which they are pulled out from the outer shaft 8. It should be noted that the mechanism for displacing the inner shaft 10 is not limited to the mechanism described above.

[0056] Next, the working method of the balloon-type electrode catheter 1 will be explained. Figure 8 (A) Figure 8 (C) and Figure 9 This is a diagram illustrating the operation of the balloon-type electrode catheter 1. For ease of explanation, some components have been omitted from the diagrams. As an example, the balloon-type electrode catheter 1 can be used in shunt surgery to create a shunt S (through-hole) in the atrial septum (IAS).

[0057] First, a preparation process is performed before using the balloon-type electrode catheter 1. During this preparation process, fluid is supplied into the balloon 4 from the fluid port 58 via the supply chamber 14a. At this time, the air port 60 is open. A portion of the fluid supplied into the balloon 4, along with the gas inside the balloon 4 and the supply chamber 14a, is discharged to the outside via the exhaust chamber 14b and the air port 60. After this venting process, the air port 60 is closed, and the fluid inside the balloon 4 is discharged through the supply chamber 14a and the fluid port 58. As a result, the balloon 4 is under negative pressure, and the balloon 4 is folded.

[0058] like Figure 8 As shown in (A), the shunt S is placed at the treatment site of the atrial septum (IAS) via puncture using an RF (Radio Frequency) needle or similar means. Next, the sheath 78 is passed through the inferior vena cava and the right atrial RA to the shunt S. Then, the guidewire GW is passed through the sheath 78 and advanced to the left atrial LA. The balloon-type electrode catheter 1 is positioned with the guidewire GW inserted into the wire lumen 22. After the guidewire GW reaches the left atrial LA, the catheter shaft 2 is passed through the sheath 78 and inserted into the body. Then, the tip of the catheter shaft 2 is advanced along the guidewire GW to the left atrial LA. The balloon 4 of the balloon-type electrode catheter 1 is inserted into the shunt S, aligned with the shunt S by aligning the small diameter portion 38. The surgeon confirms the position of the angiography marker 44 using intracardiac echocardiography (ICE) or X-ray fluoroscopy, thereby enabling the alignment of the balloon-type electrode catheter 1.

[0059] like Figure 8 As shown in (B), after balloon 4 reaches the atrial septum (IAS), the sheath 78 is pulled out, thus exposing balloon 4. With balloon 4 exposed, fluid is supplied into balloon 4 through fluid port 58, causing balloon 4 to expand in a dumbbell shape. At this time, air port 60 is closed. As balloon 4 expands, the peripheral portion of shunt S engages with the narrowed portion 28. Thus, balloon 4 is secured to the atrial septum (IAS). The peripheral portion of shunt S abuts against the electrode 46 exposed in the narrowed portion 38.

[0060] The balloon 4 has a through-hole 50. Therefore, when fluid flows into the balloon 4, such as... Figure 8 As shown in (C), fluid is discharged from the through-hole 50. This performs flushing (perfusion). The through-hole 50 is located at the top-side inclined portion 40 and the base-side inclined portion 42. Therefore, fluid can easily flow through the gap between the narrowed portion 28 and the atrial septum (IAS). Consequently, blood flow stagnation around the electrode 46 can be more effectively suppressed, and thrombus formation associated with ablation can be inhibited.

[0061] When a thrombus forms in the left atrium (LA), it is more likely to cause serious complications such as cerebral infarction compared to when it forms in the right atrium (RA). Therefore, inhibiting thrombus formation in the left atrium (LA) is more important. Furthermore, in typical shunt procedures, the tip of the balloon 4 is positioned in the left atrium (LA), and the base of the balloon 4 is positioned in the right atrium (RA). Therefore, it is preferable that the through-hole 50 is at least located in the inclined portion 40 on the tip side positioned in the left atrium (LA). This makes it easier to inhibit thrombus formation in the left atrium (LA).

[0062] Furthermore, as in this embodiment, when the through-hole 50 is positioned on both the tip-side inclined portion 40 and the base-side inclined portion 42, thrombus formation can be suppressed on both the left atrial (LA) and right atrial (RA) sides. Therefore, the safety of the shunt procedure can be further improved. It should be noted that if the through-hole 50 is positioned on at least one of the tip-side inclined portion 40 and the base-side inclined portion 42, the thrombus formation suppression effect can be significantly enhanced. Furthermore, in this embodiment, the through-hole 50 is positioned to avoid the electrode 46. This prevents the electrode 46 from being overcooled due to fluid flow. Therefore, more reliable ablation can be performed.

[0063] Next, operate the operating ring 74, as follows: Figure 9 As shown, the outer shaft 8 and the inner shaft 10 undergo relative displacement. In this embodiment, the inner shaft 10 uses the outer shaft 8 as a fulcrum to displace towards the base end of the balloon-type electrode catheter 1. As a result, the tip and base of the balloon 4 deform in a manner that approaches each other along the axial direction of the catheter shaft 2. Consequently, the tip-side inclined portion 40 and the base-side inclined portion 42 approach each other, and the contact area between the periphery of the shunt S and each inclined portion increases. Therefore, the contact area between the periphery of the shunt S and the electrode 46 also increases.

[0064] In this state, a high-frequency current is applied to electrode 46 to perform ablation. Through ablation, the periphery of the shunt S is thermally ablated. This thermal ablation modifies the periphery of the shunt S, thus making it easier to maintain the shunt S for the desired duration. It should be noted that thermal ablation can also be performed using energy other than high-frequency current.

[0065] The inflow of fluid causes the expanded balloon 4 to deform axially towards the catheter axis 2, thereby allowing the periphery of the shunt S to be clamped by the tip-side inclined portion 40 and the base-side inclined portion 42. This further suppresses electrode 46 displacement during ablation. Furthermore, the electrode 46 is more closely attached to the periphery of the shunt S, making it easier to apply high-frequency energy to the periphery of the shunt S. Additionally, the gap between the balloon 4 and the periphery of the shunt S becomes shallower, further suppressing blood stasis and even thrombus formation.

[0066] Furthermore, in this embodiment, the inner joint 32 is positioned closer to the tip of the catheter shaft 2 than the outer joint 24. As the inner joint 32 approaches the outer joint 24, the balloon 4 deforms. That is, by displacing the inner shaft 10 relative to the outer shaft 8 towards the base end, the balloon 4 is compressed axially along the catheter shaft 2. With this configuration, the load applied to the periphery of the shunt S embedded in the reduced diameter portion 28 can be suppressed, and the balloon 4 can be deformed. Therefore, the balloon 4 can be deformed more easily.

[0067] Furthermore, in this embodiment, the inner shaft 10 has a tip portion protruding from the outer shaft 8 on the side closer to the tip than the balloon 4, and a connecting member 18 is disposed at this tip portion. The diameter of the tip portion of the inner shaft 10 protruding from the outer shaft 8 is at least reduced by the thickness of the outer shaft 8. Therefore, by disposing of the connecting member 18 at the tip portion of the inner shaft 10, the increase in diameter of the catheter shaft 2 caused by the provision of the connecting member 18 can be suppressed.

[0068] Furthermore, by providing the connecting member 18 near the tip of the balloon 4, the end 46a of the electrode 46 can be easily positioned near the base of the smaller diameter portion 38. Since the smaller diameter portion 38 of the balloon 4 is positioned near the base of the right atrium RA, the end 46a of the electrode 46 is also positioned in the right atrium RA. Generally, the end 46a of the electrode 46 is prone to overheating. Therefore, by positioning the easily overheated end 46a in the right atrium RA, thrombus formation in the left atrium LA can be further suppressed. Furthermore, the balloon-type electrode catheter 1 of this embodiment includes an insulating membrane 48 covering at least a portion of the region of the electrode 46 from the connecting member 18 to the tip-side inclined portion 40. The smaller diameter portion 38 of the electrode 46 is positioned near the tip of the left atrium LA. Therefore, by providing the insulating membrane 48 in the balloon-type electrode catheter 1, thrombus formation in the left atrium LA can be further suppressed.

[0069] Furthermore, the catheter shaft 2 of this embodiment includes a supply chamber 14a for fluid to flow into the balloon 4, and an exhaust chamber 14b for gas to be discharged from the balloon 4. This prevents gas from the balloon 4 from escaping into the body through the through-hole 50. It also prevents gas from hindering contact between the electrode 46 and the fluid, thus preventing a localized temperature rise in the electrode 46 and hindering ablation. Additionally, the supply port 14a1 of the supply chamber 14a is located closer to the tip of the catheter shaft 2 than the exhaust port 14b1 of the exhaust chamber 14b. This facilitates the discharge of gas from the balloon 4.

[0070] The embodiments of this disclosure have been described in detail above. The above embodiments are merely specific examples of implementing this disclosure. The content of the embodiments does not limit the technical scope of this disclosure; many design changes, such as alterations, additions, and deletions of constituent elements, can be made without departing from the spirit of this disclosure as defined in the claims. New embodiments with applied design changes simultaneously possess the effects of both the combined embodiments and the variations. In the above embodiments, the phrases "in this embodiment" and "in this embodiment" are used to emphasize the possibility of such design changes, but design changes are permitted even without such expressions. Any combination of constituent elements included in each embodiment is also valid as a solution of this disclosure. The shading lines on the cross-sections of the drawings do not limit the material of the objects marked with shading lines.

[0071] The implementation method can also be determined by the following items.

[0072] [Project 1]

[0073] A balloon-type electrode catheter (1) comprising:

[0074] The catheter shaft (2) has a tubular outer shaft (8) and an inner shaft (10) that is accommodated in the outer shaft (8) in a state that can be relatively displaced relative to the outer shaft (8) in the axial direction of the outer shaft (8), and the catheter shaft (2) is inserted into the body;

[0075] A balloon (4), located at the tip of the catheter shaft (2), is expandable by fluid supplied from the base of the catheter shaft (2); and

[0076] Electrode (46) is disposed on the surface of balloon (4).

[0077] The balloon (4) has an outer engagement portion (24) that engages with the outer axis (2), and an inner engagement portion (32) that engages with the inner axis (10) at a position offset axially from the outer engagement portion (24). In its inflated state, the balloon (4) has a large diameter portion (34) on the tip side, a large diameter portion (36) on the basal side of the catheter axis (2) that is closer to the tip side than the large diameter portion (34), a small diameter portion (38) between the large diameter portion (34) and the basal diameter portion (36) that has a diameter smaller than the diameters of the two large diameter portions, a tip side inclined portion (40) connecting the large diameter portion (34) and the small diameter portion (38), and a basal side inclined portion (42) connecting the large diameter portion (36) and the small diameter portion (38).

[0078] The electrode (46) is exposed at least in the small diameter portion (38).

[0079] After the balloon (4) expands due to the inflow of fluid, it deforms by the relative displacement of the outer shaft (8) and the inner shaft (10) in such a way that the tip side inclined portion (40) and the base side inclined portion (42) approach each other.

[0080] [Second Project]

[0081] According to the balloon-type electrode catheter (1) described in the first item, wherein,

[0082] The inner joint (32) is positioned on the top end side of the guide tube shaft (2) relative to the outer joint (24).

[0083] The balloon (4) deforms as it approaches the outer joint (24) through the inner joint (32).

[0084] [Third Project]

[0085] According to the balloon-type electrode catheter (1) described in the first or second item, wherein,

[0086] The balloon-type electrode catheter (1) comprises: a lead wire (20) extending from the base end side of the catheter shaft (2) toward the tip side; and

[0087] A connecting member (18) is positioned at the top end of the balloon (4) near the catheter shaft (2) to electrically connect the lead wire (20) to the electrode (46).

[0088] The electrode (46) extends from the connecting member (18) through the top side inclined portion (40) to the small diameter portion (38), and the end (46a) of the electrode (46) is positioned on the base end side of the guide shaft (2) closer to the small diameter portion (38).

[0089] [Fourth Project]

[0090] According to the balloon-type electrode catheter (1) described in the third item, wherein,

[0091] The inner axis (10) has a tip portion protruding from the outer axis (8) on the apical side of the balloon (4) closer to the catheter axis (2).

[0092] The connecting member (18) is located at the top.

[0093] [Fifth Item]

[0094] According to the balloon-type electrode catheter (1) described in the third or fourth item, wherein,

[0095] The balloon-type electrode catheter (1) has an insulating membrane (48) covering at least a portion of the region from the connecting member (18) to the tip-side inclined portion (40) of the electrode (46).

[0096] [Sixth Item]

[0097] According to any one of the first to fifth items, the balloon-type electrode catheter (1), wherein,

[0098] The catheter shaft (2) has: a supply chamber (14a) for fluid to flow into the balloon (4); and an exhaust chamber (14b) for gas to be expelled from the balloon (4).

[0099] [Seventh Item]

[0100] According to the balloon-type electrode catheter (1) described in item six, wherein,

[0101] The supply chamber (14a) has a supply port (14a1) inside the balloon (4) to allow fluid to flow into the balloon (4).

[0102] The discharge chamber (14b) within the balloon (4) has an discharge port (14b1) that allows gas to flow out of the balloon (4).

[0103] The supply port (14a1) is located on the top side of the conduit shaft (2) relative to the discharge port (14b1).

[0104] [Item 8]

[0105] A method for operating a balloon-type electrode catheter (1), wherein the balloon-type electrode catheter (1) has a balloon (4) with an electrode (46) on the top end side of the catheter shaft (2), and the method for operating the balloon-type electrode catheter (1) includes:

[0106] Fluid flows into the balloon (4), causing the balloon (4) to expand in a dumbbell shape.

[0107] The balloon (4) is deformed by bringing the tip (32) and base (24) of the balloon (4) closer together along the axial direction of the catheter axis (2).

[0108] Apply current to electrode (46).

[0109] Explanation of reference numerals in the attached figures

[0110] 1. Balloon-type electrode catheter

[0111] 2 catheter axis

[0112] 4 balloons

[0113] 8 outer shafts

[0114] 10 inner shaft

[0115] 14a Supply Chamber

[0116] 14a1 supply port

[0117] 14b Discharge chamber

[0118] 14b1 discharge outlet

[0119] 18 connecting components

[0120] 20 wires

[0121] 24 External Joints

[0122] 28. Reduction section

[0123] 32 Inner Joint

[0124] 34. Top side large diameter section

[0125] 36 Large diameter portion of the base

[0126] 38 small diameter section

[0127] 40 Top Side Inclined Section

[0128] 42 Base end inclined portion

[0129] 46 electrodes

[0130] 46a end

[0131] 48 Insulating film

Claims

1. A balloon-type electrode catheter, wherein, have: A catheter shaft having a tubular outer shaft and an inner shaft accommodated within the outer shaft in a state where it can be relatively displaced relative to the outer shaft in the axial direction, the catheter shaft being inserted into the body; A balloon, located at the tip of the catheter shaft, is expandable by fluid supplied from the base of the catheter shaft. as well as Electrodes are disposed on the surface of the balloon. The balloon has: an outer engagement portion that engages with the outer axis, and an inner engagement portion that engages with the inner axis at a position offset from the outer engagement portion in the axial direction; and the balloon, in its inflated state, has: a large-diameter portion on the tip side, a large-diameter portion on the base side of the catheter axis that is closer to the base than the large-diameter portion on the tip side, a small-diameter portion located between the large-diameter portion on the tip side and the large-diameter portion on the base side and having a diameter smaller than the diameters of the two large-diameter portions, a tip-side inclined portion connecting the large-diameter portion on the tip side and the small-diameter portion, and a base-side inclined portion connecting the large-diameter portion on the base side and the small-diameter portion on the base side. The electrode is exposed at least in the small diameter portion. After the balloon expands due to the inflow of fluid, it deforms by the relative displacement of the outer axis and the inner axis, causing the inclined portion at the tip to approach the inclined portion at the base. The peripheral portion of the shunt is embedded in a reduced-diameter portion consisting of the small-diameter portion, the top-side inclined portion, and the base-side inclined portion. The peripheral portion abuts against the electrode exposed in the small-diameter portion, and the peripheral portion is ablated by applying current to the electrode.

2. The balloon-type electrode catheter according to claim 1, wherein, The inner joint is positioned on the top end side of the conduit shaft, which is closer to the outer joint than the outer joint. The balloon deforms as it approaches the outer joint through the inner joint.

3. The balloon-type electrode catheter according to claim 1 or 2, wherein, The balloon-type electrode catheter includes: a wire extending from the base end side of the catheter shaft toward the tip side, and A connecting member, positioned at the tip of the catheter shaft closer to the balloon, electrically connects the lead wire to the electrode. The electrode extends from the connecting member through the top inclined portion to the small diameter portion, and the end of the electrode is positioned on the base end side closer to the conduit axis than the small diameter portion.

4. The balloon-type electrode catheter according to claim 3, wherein, The inner shaft has a tip portion that protrudes from the outer shaft on the side closer to the catheter shaft than the balloon. The connecting member is disposed at the top end.

5. The balloon-type electrode catheter according to claim 3, wherein, The balloon-shaped electrode catheter has an insulating film covering at least a portion of the region from the connecting member to the tip-side inclined portion of the electrode.

6. The balloon-type electrode catheter according to claim 1 or 2, wherein, The catheter shaft has: a supply chamber for allowing fluid to flow into the balloon; and an exhaust chamber for allowing gas to escape from the balloon.

7. The balloon-type electrode catheter according to claim 6, wherein, The supply chamber has a supply port inside the balloon to allow the fluid to flow into the balloon. The discharge chamber has an outlet inside the balloon that allows the gas to flow out of the balloon. The supply port is located on the top side of the conduit shaft, which is closer to the outlet than the outlet.

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