JP2024120188A - Medical Devices and Methods for Forming Shunts - Google Patents

Abstract

[Problem] To provide a medical device capable of positioning an expansion body at an appropriate angle relative to biological tissue, and a method of forming a shunt using the same. [Solution] A medical device (10) comprising an expansion body (21), a long shaft section (20), and an electrode section (22), the expansion body (21) having a recess (51) that recesses radially inward when the expansion body (21) is expanded and defines a receiving space (51b) capable of receiving biological tissue, the electrode section (22) being disposed along the recess (51) so as to face the receiving space (51b), the length along the axial direction from the base end fixing section (31) to the bottom (51a) of the recess (51) being 10mm to 30mm, the shaft section (20) being formed with a first curve (60) that starts at the base end fixing section (31) or a position closer to the hand side than the base end fixing section (31) and bends in one direction toward the hand side, and a second curve (62) that starts at the base end of the first curve (60) or a position closer to the hand side than the base end and bends in the opposite direction to the first curve (60) toward the hand side. [Selected Figure] Figure 4

Description

The present invention relates to a medical device that applies energy to biological tissue and a method for forming a shunt using the same.

A known medical device is one in which an electrode portion is placed on an expandable body that expands and contracts inside the body, and ablation treatment is performed by cauterizing biological tissue with high-frequency current from the electrode portion. Shunt treatment for the atrial septum is known as one type of ablation treatment. In shunt treatment, a shunt (puncture hole) that serves as an escape route for elevated atrial pressure is formed in the fossa ovalis of the atrial septum in patients with heart failure, allowing the symptoms of heart failure to be alleviated. In shunt treatment, the atrial septum is accessed via a transvenous approach, and a shunt of the desired size is formed. Such a medical device is disclosed, for example, in Patent Document 1.

International Publication No. 2020-094094

In a medical device for performing shunt therapy, the expandable body has a recess that recesses radially inward when expanded and defines a receiving space capable of receiving biological tissue. The electrode portion described above is placed in the recess. In order to apply sufficient energy from the electrode portion to the biological tissue, the recess needs to be in close contact with the biological tissue over the entire circumference.

When the expansion body is positioned at a right angle or a close angle to the surface direction of the atrial septum, the recess can make even contact with the biological tissue over the entire circumference. If the expansion body is positioned at a large incline with respect to the atrial septum, some areas of the recess in the circumferential direction will not be able to make sufficient contact with the biological tissue, and sufficient energy cannot be applied from the electrode portion, which may prevent the shunt from being formed with the desired diameter.

The present invention has been made to solve the above-mentioned problems, and aims to provide a medical device that can position an expandable body at an appropriate angle relative to biological tissue, and a method for forming a shunt using the same.

The medical device according to the present invention, which achieves the above object, comprises an expansion body that can expand and contract in the radial direction, a long shaft portion having a base end fixing portion to which the base end of the expansion body is fixed, and an electrode portion provided along the expansion body, the expansion body has a recess that is recessed radially inward when the expansion body is expanded and defines a receiving space capable of receiving biological tissue, the electrode portion is arranged along the recess so as to face the receiving space, the length along the axial direction from the base end fixing portion to the bottom of the recess is 10 mm to 30 mm, and the shaft portion is formed with a first curve that starts at the base end fixing portion or a position closer to the hand side than the base end fixing portion and bends in one direction toward the hand side, and a second curve that starts at the base end of the first curve or a position closer to the hand side than the base end and bends in the opposite direction to the first curve toward the hand side.

The shunt formation method according to the present invention, which achieves the above-mentioned object, is a shunt formation method for forming a shunt connecting the right atrium and the left atrium in the fossa ovalis using a medical device comprising an expansion body capable of expanding and contracting in the radial direction, a long shaft portion having a base end fixing portion to which the base end of the expansion body is fixed, and an electrode portion provided along the expansion body, the expansion body has a recess that recesses radially inward when the expansion body is expanded and defines a receiving space capable of receiving biological tissue, the electrode portion is arranged along the recess so as to face the receiving space, and the shaft portion extends in a direction from the base end fixing portion or a position closer to the hand side to the base end fixing portion toward the hand side. The medical device has a first curve that bends in the direction opposite to the first curve, and a second curve that bends from the base end of the first curve or a position closer to the hand side than the base end as a starting point toward the hand side in the opposite direction to the first curve. The medical device is inserted into the right atrium from the inferior vena cava, and in the right atrium, the first curve is positioned so as to be convex in the direction away from the fossa ovalis. The contracted expandable body is inserted into a hole formed in the fossa ovalis, and the expandable body is expanded within the hole, and the biological tissue surrounding the hole is placed in the receiving space of the recess, and the biological tissue placed in the receiving space is cauterized using the electrode so as to inhibit closure of the hole due to natural healing.

The medical device and shunt formation method configured as described above allows the shaft portion to be bent from the inferior vena cava by the second curve to the opposite side of the atrial septum where the expansion body is placed, and then bent by the first curve to the atrial septum side, so that the expansion body can be positioned at an angle close to perpendicular to the atrial septum. This allows the recess to be brought into close contact with the biological tissue over the entire circumferential direction, ensuring the formation of a shunt of the desired size.

The shaft portion has a bending angle of the first curve defined as α (°), a bending radius of the first curve defined as 1 (mm), a bending angle of the second curve defined as β (°), a bending radius of the second curve defined as r (mm), and an axial length of the expansion body defined as L (mm),
(l-lcos(α-β))+(r-rcosβ))≦15mm
Lsin45°+lsin(α-β)+lsinβ≦40mm
35°≦α-β≦55°
In this way, by directing the expandable body from the inferior vena cava toward the atrial septum, it is possible to reliably position the expandable body at an appropriate angle with respect to the atrial septum.

The shaft portion may have the first curve and the second curve in advance before being inserted into the living body. This allows the expansion body to be reliably positioned at an appropriate angle simply by inserting the shaft portion to the target site.

The shaft portion may have a bending operation portion, and the first curve and the second curve may be formed in the shaft portion by operating the bending operation portion while the shaft portion and the expansion body are placed inside the living body. This allows the expansion body to be reliably positioned at an appropriate angle by operating the bending operation portion.

The first curve and the second curve may be arranged in the right atrium with the expansion body arranged in the atrial septum. This allows the shaft portion extending from the inferior vena cava to bend in two directions in the right atrium, ensuring that the expansion body is arranged at an angle close to perpendicular to the atrial septum.

FIG. 1 is a front view showing an overall configuration of a medical device according to an embodiment. FIG. FIG. FIG. 2 is an enlarged view of the tip of the shaft portion and the expansion body. FIG. 13 is an explanatory diagram showing a state in which an expansion body is placed in the atrial septum, with the medical device shown in a front view and the biological tissue shown in a cross-sectional view. 1 is a flowchart of a procedure using a medical device. 7A and 7B are diagrams showing the state S2 in FIG. 6, in which (a) is an enlarged view of the atrial septum in cross section near the balloon, and (b) is a cross-sectional view of the atrial septum showing the shape of the puncture hole. 7A and 7B are diagrams showing the state S3 in Figure 6, in which (a) shows a cross-section of the atrial septum and an enlarged view of the vicinity of the expandable body showing the inside of the storage sheath in a see-through manner, and (b) is a cross-sectional view of the atrial septum with the storage sheath inserted through the puncture hole. 13 is a cross-sectional view of the heart in a state in which a storage sheath containing an expandable body is placed in a puncture hole. FIG. 13 is a cross-sectional view of the heart with the distal end side of the expandable body exposed from the housing sheath. FIG. FIG. 13 is an enlarged view of the vicinity of the expansion body, showing the atrial septum in cross section with the expansion body with its tip side exposed in contact with the atrial septum. FIG. 13 is an enlarged view of the vicinity of the expansion body, showing a cross section of the atrial septum with the expansion body entirely exposed. FIG. 13 is an enlarged view of the vicinity of the expandable body, showing a cross section of the atrial septum when a first curve and a second curve are formed in the shaft portion. FIG. 7 is a diagram showing the state of S4 in FIG. 6, and is a cross-sectional view of the atrial septum in a state in which the puncture hole has been expanded by an expandable body. FIG. 7 is a diagram showing the state S5 in FIG. 6, and is an enlarged view of the vicinity of the expansion body showing the atrial septum in cross section. FIG. 13 is an enlarged view of a shaft portion and an expansion body according to a first modified example. FIG. 13 is an enlarged view of a shaft portion and an expansion body according to a second modified example. 13A and 13B are enlarged views of a shaft portion and an expansion body according to a third modified example, in which FIG. 13A illustrates the state of the shaft portion before deformation, and FIG. 13B illustrates the state of the shaft portion after deformation.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated for the sake of explanation and may differ from the actual ratios. In addition, in this specification, the side of the medical device 10 that is inserted into a cavity in the body will be referred to as the "tip" or "tip side", and the side that is operated by the hand will be referred to as the "base end" or "base side".

The medical device in the following embodiment is configured to expand a puncture hole Hh formed in the atrial septum HA of a patient's heart H, and to perform a maintenance procedure to maintain the expanded puncture hole Hh at its size.

As shown in FIG. 1, the medical device 10 of this embodiment has a long shaft portion 20, an expansion body 21 provided at the tip of the shaft portion 20, and a hand-operated portion 23 provided at the base end of the shaft portion 20. The expansion body 21 is provided with an electrode portion 22, which is an energy transmission element for performing the maintenance treatment described above.

The shaft portion 20 has a distal shaft portion 30 including a base end fixing portion 31 to which the base end of the expansion body 21 is fixed, and a distal end fixing portion 33 to which the distal end of the expansion body 21 is fixed. The distal shaft portion 30 extends inside the expansion body 21 from the base end to the distal end of the expansion body 21.

The shaft portion 20 has a storage sheath 25 provided at the outermost periphery. The expansion body 21 can move axially forward and backward relative to the storage sheath 25. When the storage sheath 25 is moved to the tip side of the shaft portion 20, it can store the expansion body 21 inside. When the storage sheath 25 is moved to the base end side from a state in which the expansion body 21 is stored, the expansion body 21 can be exposed.

A traction shaft 26 is disposed inside the shaft portion 20. The traction shaft 26 is provided from the proximal end side of the hand operation unit 23 to the distal end side of the expansion body 21, protrudes from the distal end of the shaft portion 20, is connected to the distal end of the expansion body 21, and is slidable relative to the shaft portion 20. The distal end of the traction shaft 26 is fixed to the distal end member 35.

The tip member 35 to which the tip of the traction shaft 26 is fixed does not need to be fixed to the expansion body 21. This allows the tip member 35 to apply a compressive force to the expansion body 21 along the axis of the shaft portion 20 as the traction shaft 26 slides in the base end direction relative to the shaft portion 20. In addition, when storing the expansion body 21 in the storage sheath 25, moving the tip member 35 away from the expansion body 21 toward the tip side makes it easier for the expansion body 21 to move in the extension direction, improving storage properties.

The handheld operation unit 23 has a housing 40 that is held by the surgeon, an operation dial 41 that can be rotated by the surgeon, and a conversion mechanism 42 that operates in conjunction with the rotation of the operation dial 41. The towing shaft 26 is held by the conversion mechanism 42 inside the handheld operation unit 23. The conversion mechanism 42 can move the towing shaft 26 it holds forward and backward along the axial direction in response to the rotation of the operation dial 41. For example, a rack and pinion mechanism can be used as the conversion mechanism 42.

The shaft portion 20 is preferably made of a material that has a certain degree of flexibility. Examples of such materials include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or mixtures of two or more of these, soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, fluororesins such as polytetrafluoroethylene, polyimide, PEEK, silicone rubber, latex rubber, etc.

The traction shaft 26 can be formed from a long wire material such as a superelastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, a metal material such as stainless steel, or a resin material with relatively high rigidity.

The tip member 35 can be made of, for example, a superelastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, a metal material such as stainless steel, a polymer material such as polyolefin, polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, or fluororesin, or a mixture of these, or a multi-layer tube of two or more types of polymer materials.

The expandable body 21 will be described in more detail. As shown in Figures 2 and 3, the expandable body 21 has multiple wire parts 50 in the circumferential direction. The wire parts 50 branch and merge along the length direction to form a mesh-like structure. This allows the expandable body 21 to expand and contract in the radial direction. The base end of the wire part 50 extends from the base end fixing part 31 to the tip side. The tip of the wire part 50 extends from the base end of the tip fixing part 33 to the base end side. The wire part 50 is inclined so that it becomes larger in the radial direction from both ends in the axial direction toward the center. In addition, the wire part 50 has a recess 51 in the axial center that is recessed radially inward of the expandable body 21. The radially innermost part of the recess 51 is the bottom part 51a. The recess 51 defines a receiving space 51b that can receive biological tissue when the expandable body 21 is expanded.

The recess 51 has a base-side rising portion 52 extending radially outward from the base end of the bottom portion 51a, and a tip-side rising portion 53 extending radially outward from the tip of the bottom portion 51a. When the traction shaft 26 slides in the base-side direction relative to the shaft portion 20 and a compressive force is applied to the expansion body 21, the tip-side rising portion 53 and the base-side rising portion 52 approach each other and are in close contact with the biological tissue received in the receiving space 51b. The electrode portion 22 is arranged along the recess 51 on the base-side rising portion 52 so as to face the receiving space 51b. The tip-side rising portion 53 has an outer edge portion 55 that branches into two from the vicinity of the bottom portion 51a and extends radially outward, and a backrest portion 56 that is arranged between the two outer edge portions 55. The electrode portion 22 may be arranged on the tip-side rising portion 53.

The wire section 50 that forms the expansion body 21 can be formed by laser cutting a single metal cylindrical member. The wire section 50 can be formed from a metal material. Examples of the metal material that can be used include titanium alloys (Ti-Ni, Ti-Pd, Ti-Nb-Sn, etc.), copper alloys, stainless steel, beta titanium steel, and Co-Cr alloys. It is better to use alloys that have spring properties, such as nickel-titanium alloys. However, the materials of the wire section 50 are not limited to these, and it may be formed from other materials.

The electrode units 22 are connected to an external device, an energy supply device (not shown), by a conductor (not shown) covered with an insulating coating material. A high-frequency voltage is applied between the two electrode units 22 from the energy supply device via the conductor, and energy is imparted between them.

Next, the shape of the tip of the shaft portion 20 will be described. As shown in FIG. 4, the shaft portion 20 is pre-shaped to have a first curve 60 that starts from the position of the base end fixing portion 31 of the expansion body 21 and bends in one direction toward the hand side, and a second curve 62 that starts from the base end position of the first curve 60 and bends in the opposite direction to the first curve 60 toward the hand side. The first curve 60 and the second curve 62 give the shaft portion 20 a shape that is bent in an approximately S-shape. Here, the bending angle of the first curve 60 is α (°), the bending radius of the first curve 60 is 1 (mm), the bending angle of the second curve 62 is β (°), the bending radius of the second curve 62 is r (mm), and the axial length of the expansion body 21 is L (mm).

The diameter of the space formed inside the recess 51 must be 4 mm or more. If the length L/2, half the axial length L of the expansion body 21, is less than 10 mm, the self-expansion force of the expansion body 21 will exceed the limit of its storage in the storage sheath 25. If L/2 exceeds 30 mm, the bending radius l of the first curve 60 of the shaft portion 20 must be reduced, and the storage sheath 25 storing the shaft portion 20 may kink. For this reason, the expansion body 21 is formed so that the length of L/2 is in the range of 10 mm to 30 mm. The length of L/2 is more preferably set to 15 mm to 25 mm. This allows the bending angle of the shaft portion 20 to be small and the bending radius to be large, reducing the risk of kinking of the storage sheath 25 when delivering the medical device 10, and also allows the expansion body 21 to have a self-expansion force that is easy to store in the storage sheath 25.

As shown in FIG. 5, the expansion body 21 that has entered the right atrium HRa from the inferior vena cava Iv is placed in the puncture hole Hh formed at the position of the fossa ovalis of the atrial septum HA to perform the maintenance procedure. At this time, the shaft portion 20 is placed in the right atrium HRa from the tip side having the expansion body 21 toward the hand side so that the first curve 60 is convex in the direction away from the fossa ovalis, and reaches the inferior vena cava Iv via the second curve 62 that bends in the opposite direction to the first curve 60. Since the shaft portion 20 has the second curve 62 that bends in the opposite direction to the first curve 60, the first curve 60 passes near the posterior wall of the right atrium HRa that faces the atrial septum HA, and the bending radius of the first curve 60 can be increased. This allows the expansion body 21 to be placed at an angle close to perpendicular to the atrial septum HA.

The bending radius and bending angle of the first curve 60 and the second curve 62 can be set arbitrarily depending on the size, shape, etc. of the heart to be used, but it is preferable to set them so as to satisfy all of the relationships (1) to (3) below. In this way, by directing the expandable body 21 from the inferior vena cava Iv toward the atrial septum HA, it is possible to reliably position the expandable body 21 at an appropriate angle relative to the atrial septum HA.
(l-lcos(α-β))+(r-rcosβ))≦15mm (1)
Lsin45°+lsin(α-β)+lsinβ≦40mm (2)
35°≦α－β≦55° (3)

A treatment method using the medical device 10 will be described. The treatment method of this embodiment is performed on a patient suffering from heart failure (left ventricular failure). More specifically, as shown in FIG. 5, this is a treatment method performed on a patient suffering from chronic heart failure in which the blood pressure of the left atrium HLa increases due to hypertrophy of the myocardium of the left ventricle of the heart H and increased stiffness.

As shown in FIG. 6, first, a puncture hole Hh is created in the atrial septum HA (S1). When forming the puncture hole Hh, the surgeon delivers an introducer, which is a combination of a guiding sheath and a dilator, to the vicinity of the atrial septum HA. The introducer can be delivered to the right atrium HRa, for example, via the inferior vena cava Iv. The introducer can also be delivered using a guidewire. The surgeon can insert the guidewire through the dilator and deliver the introducer along the guidewire. Note that insertion of the introducer and the guidewire into the living body can be performed by a known method, such as using an introducer for introducing blood vessels.

The surgeon passes a puncture device (not shown) from the right atrium HRa to the left atrium HLa to form a puncture hole Hh. The puncture device is passed through a dilator and delivered to the atrial septum HA.

Next, the surgeon delivers the balloon catheter 100 to the vicinity of the atrial septum HA along the guide wire 11 that has been inserted beforehand. As shown in FIG. 7, the balloon catheter 100 has a balloon 102 at the tip of the shaft portion 101. Once the balloon 102 is positioned in the atrial septum HA, it is expanded radially as shown in FIG. 7(a) to push open the puncture hole Hh (S2). At this time, due to the influence of the fibers of the septal tissue, the puncture hole Hh expands to the maximum diameter of the expanded balloon 102 in the direction along the fibers, but is difficult to expand in other directions, resulting in an elongated shape as shown in FIG. 7(b).

Next, the medical device 10 is delivered from the inferior vena cava Iv through the right atrium HRa to the vicinity of the atrial septum HA, and the expansion body 21 is placed at the position of the puncture hole Hh (S3). No guidewire is used when delivering the medical device 10, but a guidewire may be used for stable operation under pulsation.

The tip of the medical device 10 penetrates the atrial septum HA and reaches the left atrium HLa. As shown in FIG. 8(a), when the medical device 10 is inserted, the expansion body 21 is stored in the storage sheath 25. Note that the shape of the expansion body 21 is simplified in this figure and in FIGS. 11 to 13 and 15. As shown in FIG. 8(b), the puncture hole Hh is expanded by the balloon 102, so that the storage sheath 25 can be inserted through the puncture hole Hh. The storage sheath 25, which stores the expansion body 21 and the shaft portion 20 inside, extends from the inferior vena cava Iv toward the atrial septum HA as shown in FIG. 9, so that the tip of the storage sheath 25 is inclined with respect to the vertical direction of the atrial septum HA.

Next, the storage sheath 25 is moved toward the base end, and about half of the tip side of the expansion body 21 is exposed to the outside of the storage sheath 25, and is expanded in the left atrium HLa. Even at this stage, as shown in FIG. 10, the storage sheath 25 is inclined with respect to the vertical direction of the atrial septum HA. Next, the entire medical device 10 is moved toward the base end, and the tip side standing part 53 of the expansion body 21 is abutted against the atrial septum HA, as shown in FIG. 11. At this time, since the axial direction of the expansion body 21 is inclined with respect to the vertical direction of the atrial septum HA, the lower side of the expansion body 21 is not abutted against the atrial septum HA. From this state, the storage sheath 25 is moved toward the base end, and as shown in FIG. 12, the entire expansion body 21 is exposed to the outside of the storage sheath 25 and expanded. Even at this stage, the axial direction of the expansion body 21 is inclined relative to the perpendicular direction of the atrial septum HA, so the upper base end standing part 52 of the expansion body 21 does not abut the atrial septum HA, and part of the electrode part 22 is far removed from the biological tissue. In addition, the lower side of the atrial septum HA is pushed toward the left atrium HLa by the base end standing part 52 of the expansion body 21.

Next, as shown in FIG. 5, the storage sheath 25 is moved toward the base end so that the tip end is positioned near the entrance of the inferior vena cava Iv, and the shaft portion 20 exposed from the storage sheath 25 forms a first curve 60 and a second curve 62 in the right atrium HRa. By positioning the shaft portion 20 so that the first curve 60 is convex in the direction away from the fossa ovalis, the expansion body 21 can be positioned at an angle close to perpendicular to the atrial septum HA as shown in FIG. 13. This allows the receiving space 51b of the expansion body 21 to receive the biological tissue surrounding the puncture hole Hh (S4).

As shown in FIG. 14, the expansion of the expansion body 21 expands the puncture hole Hh to have a substantially uniform diameter along the circumferential direction. The expansion body 21 changes the shape of the puncture hole Hh, but does not expand the maximum diameter. Therefore, the maximum diameter of the puncture hole Hh is equal to the diameter in the major axis direction of the puncture hole Hh expanded by the balloon 102 in S2.

With the receiving space 51b receiving the biological tissue, the surgeon operates the operating unit 23 to move the traction shaft 26 toward the base end. As a result, as shown in FIG. 15, the expandable body 21 is pulled in the compression direction by the distal member 35, and is compressed in the axial direction, the atrial septum HA is grasped by the proximal side standing portion 52 and the distal side standing portion 53, and the electrode portion 22 is pressed against the biological tissue (S5).

The expandable body 21 has a shaft portion 20 with a first curve 60 and a second curve 62, and is positioned at an angle close to perpendicular to the atrial septum HA, so that all of the electrode portions 22 can be pressed evenly against the biological tissue.

After the puncture hole Hh is expanded, the surgeon checks the hemodynamics (S6). As shown in FIG. 5, the surgeon delivers a hemodynamics checking device 120 to the right atrium HRa via the inferior vena cava Iv. As the hemodynamics checking device 120, for example, a known echo catheter can be used. The surgeon can display the echo image acquired by the hemodynamics checking device 120 on a display device such as a display, and check the amount of blood passing through the puncture hole Hh based on the display result.

Next, the surgeon performs a maintenance procedure to inhibit closure of the puncture hole Hh due to natural healing and to maintain its size (S7). In the maintenance procedure, high-frequency energy is applied to the edge of the puncture hole Hh through the electrode portion 22, thereby cauterizing (heating and cauterizing) the edge of the puncture hole Hh with the high-frequency energy. The high-frequency energy is applied by applying a voltage between a pair of electrode portions 22 adjacent in the circumferential direction.

When the biological tissue near the edge of the puncture hole Hh is cauterized through the electrode portion 22, a denatured portion is formed near the edge where the biological tissue has denatured. Since the biological tissue in the denatured portion loses its elasticity, the puncture hole Hh can maintain the shape it had when it was expanded by the expander 21.

After the maintenance procedure, the surgeon checks the hemodynamics again (S8), and if the amount of blood passing through the puncture hole Hh is the desired amount, the surgeon reduces the diameter of the expandable body 21, stores it in the storage sheath 25, and removes it from the puncture hole Hh. Furthermore, the entire medical device 10 is removed from the living body, and the procedure is completed.

As described above, the shapes of the first curve 60 and the second curve 62 of the shaft portion 20 can be set arbitrarily within a certain range that satisfies the above conditions (1) to (3). As shown in FIG. 16, the shape can be changed from a shape in which the bending radius l of the first curve 60 is minimum and the bending radius r of the second curve 62 is maximum to a shape in which the bending radius l of the first curve 60 is maximum and the bending radius r of the second curve 62 is minimum, as shown in FIG. 17.

The first curve 60 may be bent from a position closer to the hand side than the base end fixing part 31 of the shaft part 20. The second curve 62 may be bent from a position closer to the hand side than the base end of the first curve 60.

The first curve 60 and the second curve 62 of the shaft portion 20 may not be formed in advance, and may be formed in vivo. As shown in FIG. 18(a), the shaft portion 20 is straight and has a bending operation portion 70 for bending the shaft portion 20. The bending operation portion 70 has a distal end ring 71 and a proximal end ring 73 fixed to the shaft portion 20, a first wire 72 whose distal end is fixed to the distal end ring 71, and a second wire 74 whose distal end is fixed to the proximal end ring 73. The first wire 72 and the second wire 74 are fixed at positions opposite each other in the circumferential direction of the shaft portion 20. In addition, both the first wire 72 and the second wire 74 extend to the proximal portion.

After delivering the expansion body 21 to the atrial septum HA, as shown in FIG. 18(b), the first wire 72 and the second wire 74 are pulled from the proximal side, causing the shaft portion 20 to bend from the distal ring 71 and the proximal ring 73 positions, respectively. The shaft portion 20 bent from the distal ring 71 position forms a first curve 60. The shaft portion 20 bent from the proximal ring 73 position forms a second curve 62 by bending in the opposite direction to the first curve 60. This allows the expansion body 21 to be positioned at an angle close to perpendicular to the atrial septum HA. The first wire 72 and the second wire 74 may be pulled simultaneously or sequentially.

As described above, the medical device 10 according to this embodiment comprises an expansion body 21 that can expand and contract radially, a long shaft portion 20 having a base end fixing portion 31 to which the base end of the expansion body 21 is fixed, and an electrode portion 22 that is provided along the expansion body 21, the expansion body 21 having a recess 51 that recesses radially inward when the expansion body 21 expands and defines a receiving space 51b that can receive biological tissue, and the electrode portion 22 is arranged along the recess 51 so as to face the receiving space 51b, The length along the axial direction from the base end fixing part 31 to the bottom 51a of the recess 51 is 10 mm to 30 mm, and the shaft part 20 is formed with a first curve 60 that starts from the base end fixing part 31 or a position closer to the hand side than the base end fixing part 31 and bends in one direction toward the hand side, and a second curve 62 that starts from the base end of the first curve 60 or a position closer to the hand side than the base end and bends in the opposite direction to the first curve 60 toward the hand side.

The shunt formation method according to this embodiment is a shunt formation method for forming a shunt connecting the right atrium and the left atrium in the fossa ovalis using a medical device 10 including an expansion body 21 that can expand and contract in the radial direction, a long shaft portion 20 having a base end fixing portion 31 to which the base end of the expansion body 21 is fixed, and an electrode portion 22 provided along the expansion body 21, the expansion body 21 having a recess 51 that recesses radially inward when the expansion body 21 is expanded and defines a receiving space 51b that can receive biological tissue, the electrode portion 22 is arranged along the recess 51 so as to face the receiving space 51b, and the shaft portion 20 is extended from the base end fixing portion 31 or a position closer to the hand than the base end fixing portion 31 as a starting point. The medical device 10 has a first curve 60 that bends in one direction toward the hand side, and a second curve 62 that bends in the opposite direction to the first curve 60 toward the hand side, starting from the base end of the first curve 60 or a position closer to the hand side than the base end. The medical device 10 is inserted into the right atrium from the inferior vena cava, and in the right atrium, the first curve 60 is positioned so that it is convex in the direction away from the fossa ovalis. In this state, the contracted expandable body 21 is inserted into the hole formed in the fossa ovalis, and the expandable body 21 is expanded within the hole, and the biological tissue surrounding the hole is placed in the receiving space 51b of the recess 51, and the biological tissue placed in the receiving space 51b is cauterized using an electrode to prevent the hole from closing due to natural healing.

The medical device 10 and shunt formation method configured in this manner can be arranged so that the shaft portion 20 is first bent from the inferior vena cava by the second curve 62 to the opposite side of the atrial septum where the expansion body 21 is placed, and then bent toward the atrial septum by the first curve 60, so that the expansion body 21 can be positioned at an angle close to perpendicular to the atrial septum. This allows the recess 51 to be brought into close contact with the biological tissue over the entire circumferential direction, ensuring the formation of a shunt of the desired size.

In the shaft portion 20, the bending angle of the first curve 60 is α (°), the bending radius of the first curve 60 is 1 (mm), the bending angle of the second curve 62 is β (°), the bending radius of the second curve 62 is r (mm), and the axial length of the expansion body 21 is L (mm).
(l-lcos(α-β))+(r-rcosβ))≦15mm
Lsin45°+lsin(α-β)+lsinβ≦40mm
35°≦α-β≦55°
In this way, by directing the expandable body 21 from the inferior vena cava toward the atrial septum, it is possible to reliably position the expandable body 21 at an appropriate angle with respect to the atrial septum.

The shaft portion 20 may be configured to have the first curve 60 and the second curve 62 in advance before being inserted into the living body. This allows the expansion body 21 to be reliably positioned at an appropriate angle simply by inserting the shaft portion 20 to the target site.

The shaft portion 20 may have a bending operation portion 70, and the first curve 60 and the second curve 62 may be formed in the shaft portion 20 by operating the bending operation portion 70 while the shaft portion 20 and the expansion body 21 are placed inside the living body. This allows the expansion body 21 to be reliably positioned at an appropriate angle by operating the bending operation portion 70.

The first curve 60 and the second curve 62 may be arranged in the right atrium with the expansion body 21 positioned in the atrial septum. This allows the shaft portion 20 extending from the inferior vena cava to bend in two directions in the right atrium, ensuring that the expansion body 21 is positioned at an angle close to perpendicular to the atrial septum.

The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical concept of the present invention.

LIST OF SYMBOLS 10 Medical device 11 Guide wire 20 Shaft portion 21 Expansion body 22 Electrode portion 23 Hand operation portion 25 Storage sheath 26 Traction shaft 30 Distal shaft portion 31 Base end fixing portion 33 Distal end fixing portion 35 Distal member 40 Housing 41 Operation dial 42 Conversion mechanism 50 Wire portion 51 Recess 51a Bottom portion 51b Receiving space 52 Base end side standing portion 53 Distal end side standing portion 55 Outer edge portion 56 Backrest portion 56a Receiving surface 57 Arm portion 57a Bending portion 60 First curve 62 Second curve 70 Bending operation portion 71 Distal end side ring 72 First wire 73 Base end side ring 74 Second wire

Claims (6)

An expandable body that is radially expandable and contractable;
A long shaft portion having a base end fixing portion to which the base end of the expansion body is fixed;
An electrode portion provided along the expansion body;
Equipped with
The expandable body has a recess that is recessed radially inward when the expandable body is expanded and defines a receiving space capable of receiving biological tissue,
The electrode portion is disposed along the recess so as to face the receiving space,
The length along the axial direction from the base end fixing portion to the bottom of the recess is 10 mm to 30 mm,
A medical device in which the shaft portion is formed with a first curve that bends in one direction toward the hand side, starting from the base end fixing portion or a position closer to the hand side than the base end fixing portion, and a second curve that bends in the opposite direction to the first curve, starting from the base end of the first curve or a position closer to the hand side than the base end. The shaft portion has a bending angle of the first curve defined as α (°), a bending radius of the first curve defined as 1 (mm), a bending angle of the second curve defined as β (°), a bending radius of the second curve defined as r (mm), and an axial length of the expansion body defined as L (mm),
(l-lcos(α-β))+(r-rcosβ))≦15mm
Lsin45°+lsin(α-β)+lsinβ≦40mm
35°≦α-β≦55°
The medical device according to claim 1 , which satisfies all of the following relationships: The medical device according to claim 1 or 2, wherein the shaft portion has the first curve and the second curve in advance before being inserted into a living body. The shaft portion has a bending operation portion,
A medical device as described in claim 1 or 2, wherein the first curve and the second curve are formed in the shaft portion by operating the bending operating portion while the shaft portion and the expansion body are placed inside a living body. The medical device according to any one of claims 1 to 4, wherein the first curve and the second curve are placed in the right atrium with the expansion body placed in the atrial septum. A shunt formation method for forming a shunt in the fossa ovalis connecting the right atrium and the left atrium by using a medical device including an expansion body that can be expanded and contracted in a radial direction, a long shaft portion having a base end fixing portion to which the base end of the expansion body is fixed, and an electrode portion provided along the expansion body,
The expandable body has a recess that is recessed radially inward when the expandable body is expanded and defines a receiving space capable of receiving biological tissue,
The electrode portion is disposed along the recess so as to face the receiving space,
the shaft portion has a first curve that is bent in one direction toward the proximal side from the base end fixing portion or a position closer to the proximal side than the base end fixing portion as a starting point, and a second curve that is bent in an opposite direction to the first curve from a base end of the first curve or a position closer to the proximal side than the base end as a starting point,
Inserting the medical device into the right atrium via the inferior vena cava;
inserting the contracted expandable body into a hole formed in the fossa ovalis in a state in which the first curve is disposed in the right atrium so as to be convex in a direction away from the fossa ovalis;
Expanding the expandable body within the hole to place the biological tissue surrounding the hole in the receiving space of the recess;
A shunt formation method, comprising cauterizing the biological tissue disposed in the receiving space using the electrode portion so as to inhibit closure of the hole by natural healing.

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