medical devices

Abstract

In order to provide a medical device and a shunt formation method with which susceptibility to the effects of variations in the thickness of biological tissue is reduced, excess expansion of a hole in the biological tissue is inhibited, and suitable and highly safe cauterization is made possible, the present invention is provided with an expansion body (21), an elongated shaft part (31) to which the base end of the expansion body is fixed, a plurality of energy transmission elements (22) disposed along the expansion body, and a traction shaft (33). The traction shaft is configured to slide against the shaft part (31) in the base end direction to apply, through a force-receiving part (51) to the expansion body, a compressive force that applies a compression along the axis of the shaft part so that a plurality of energy transmission element disposition parts (81) and a plurality of facing parts (82) approach each other. The expansion body has buffer parts (64) that are disposed in a first expansion part (53) and that are configured to deform in a direction different to the direction heading from the force-receiving part to a distal-end-side top part (57) along a distal-end-side expansion part (56), and thereby relieve the compressive force.

Description

[Technical Field]

[0001] The present invention relates to a medical device having an expandable body that expands in vivo. Su Regarding. [Background technology]

[0002] Chronic heart failure is known as a type of heart disease. Chronic heart failure is broadly divided into systolic dysfunction and diastolic dysfunction based on indicators of cardiac function. In patients with diastolic dysfunction, the myocardium becomes enlarged and stiff, causing increased blood pressure in the left atrium and a decrease in the heart's pumping function. This can lead to the patient exhibiting symptoms of heart failure, such as pulmonary edema. There are also heart diseases in which increased blood pressure in the right atrium due to pulmonary hypertension and other conditions can cause the heart's pumping function to decrease, resulting in symptoms of heart failure.

[0003] In recent years, shunt therapy has been attracting attention for these heart failure patients, in which a shunt (a through-hole) is formed in the atrial septum as an escape route for elevated atrial pressure, thereby alleviating the symptoms of heart failure. In shunt therapy, the atrial septum is accessed via a transvenous approach, and a through-hole of a desired size is formed. Examples of medical devices for performing such atrial septal shunt therapy include those described in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 094094 Summary of the Invention [Problem to be solved by the invention]

[0005] The medical device described in Patent Document 1 clamps biological tissue from the distal and proximal ends using two expandable bodies that can expand around the axis of a long shaft, and brings electrode portions, which are multiple energy transmission elements arranged circumferentially on one of the expandable bodies, into contact with the biological tissue so that they are arranged circumferentially around the hole in the biological tissue to be treated.Energy is then applied from the multiple electrode portions to cauterize the biological tissue.

[0006] When grasping tissue to press the electrodes against it, the compressive force of the expandable body by the traction shaft varies greatly depending on the thickness of the tissue.When the tissue is thick, a larger compressive force than expected is applied to the electrode, which may cause the pores in the biological tissue to expand more than expected.

[0007] The present invention has been made to solve the above-mentioned problems, and provides a medical device that is less susceptible to variations in the thickness of biological tissue, prevents excessive dilation of holes in biological tissue, and enables safe and appropriate cauterization. Su The purpose is to provide. [Means for solving the problem]

[0008] The medical device according to the present invention, which achieves the above-mentioned object, comprises an expandable body capable of expanding and contracting in a radial direction and having a distal end including a force receiving portion, a long shaft portion having a distal end to which a base end of the expandable body is fixed, a plurality of energy transmission elements provided along the expandable body, and a traction shaft disposed inside the shaft portion, protruding from the distal end of the shaft portion, connectable to the force receiving portion of the expandable body, and slidable relative to the shaft portion, wherein the expandable body has a distal expansion portion extending radially outward from the force receiving portion toward the base end, and a distal apex portion disposed on the base end side of the distal expansion portion and curved convexly outward in the radial direction. a first expansion section including a proximal expansion section extending radially outward from the distal end of the shaft section toward the distal direction, a second expansion section including a proximal apex section disposed at the distal end of the proximal expansion section and curved convexly radially outward, and a recess section recessed radially inward and extending to connect the proximal apex section and the distal apex section, defining an accepting space capable of accepting biological tissue when the expandable body is expanded, wherein the recess section has a bottom section located at the innermost radial position, a distal upright section extending radially outward from the distal end of the bottom section to the distal upright section, and a proximal upright section extending radially outward from the proximal end of the bottom section to the proximal apex section. ofthe traction shaft is configured to apply a compressive force along the axis of the shaft portion via the force receiving portion to the expandable body, compressing the expandable body along the axis of the shaft portion so that the energy transfer element arrangement portions and the opposing portions approach each other by sliding relative to the shaft portion in the proximal direction; and the expandable body has a buffer portion disposed in the first expandable portion and configured to relieve the compressive force by deforming in a direction different from the direction from the force receiving portion toward the distal apex along the distal expandable portion, or a buffer portion disposed in the second expandable portion and configured to relieve the compressive force by deforming in a direction different from the direction from the base end of the expandable body toward the proximal apex along the proximal expandable portion. The energy transmission element arrangement section is provided on the base end side standing section, and the buffer section is provided only on the tip end side expanding section. do. [Effects of the Invention]

[0010] The medical device configured as above S When a compressive force acts on the expandable body due to the traction of the traction shaft, the buffer part deforms in a direction different from the direction from the force receiving part to the tip end apex, or in a direction different from the direction from the base end of the expandable body to the base end apex, thereby alleviating the compressive force, thereby preventing the expandable body from expanding too far outward in the radial direction. Therefore, it is possible to prevent the variation in the amount of radial outward expansion of the expandable body depending on whether the biological tissue received in the receiving space is thick or thin. For this reason, this medical device S This makes it less susceptible to variations in the thickness of biological tissue, prevents the holes in the biological tissue from being expanded too much, and enables safe and appropriate cauterization.

[0011] The first expansion section may have a plurality of distal strut structures that extend radially outward from the force receiving section toward the base end and form the distal expansion section, and each of the distal strut structures may have a bending section as the buffer section that can bend along the respective distal strut structure in a direction different from the direction from the force receiving section toward the distal apex. This allows the buffer section to be realized with a simple structure.

[0012] Each of the plurality of distal strut structures may have a first section including a first strut extending from the force-receiving portion substantially parallel to the axis of the expandable body when viewed from the outside in the radial direction, and a second section including two second struts bifurcating from a base end of the first section substantially along the circumferential direction of the expandable body and connected to the distal apex, wherein the second section functions as the buffer portion that alleviates the compressive force by curving so as to increase the branching angle formed by the two branching second struts. In this way, the second section of the distal strut structure, by curving so as to increase the branching angle formed by the two branching second struts, can alleviate the compressive force and prevent the expandable body from expanding excessively radially outward.

[0013] The second section may have a plurality of junctions near the distal apex where each of the two second struts joins with one of the two second struts of another circumferentially adjacent second section, thereby forming a configuration in which adjacent distal strut structures support each other in the circumferential direction, making the expandable body less likely to twist during expansion.

[0014] The second section may have an auxiliary bending portion functioning as the buffer portion between the distal end apex and the plurality of confluence portions, which are arranged in the same phase as the energy transfer element arrangement portion or the opposing portion in the circumferential direction of the expansion body. In this way, the auxiliary bending portion can deform to further relieve the compressive force, making it more difficult for the compressive force to be converted into the expansion force.

[0015] The plurality of distal strut structures may have twice the number of first sections and junctions as the plurality of energy transfer elements, and the junctions may alternate in the circumferential direction of the expandable body between first junctions arranged in the same phase as the plurality of energy transfer element arrangements and the plurality of opposing sections and second junctions arranged in a different phase from the plurality of energy transfer element arrangements and the plurality of opposing sections. This allows the expandable body to be configured such that adjacent distal strut structures support each other in the circumferential direction, making it less likely to twist during expansion.

[0016] An auxiliary bending section functioning as the buffer section may be provided between the first confluence section and the distal apex section, whereby the deformation of the auxiliary bending section can further reduce the compressive force, making it more difficult for the compressive force to be converted into an expansive force.

[0017] The recess may have a concave strut structure connected to the distal strut structure via the distal apex and defining the distal upright portion, the proximal upright portion, and the bottom, the concave strut structure having a plurality of bottom connectors at the bottom that connect the plurality of energy transfer element arrangements to each pair of the plurality of opposing portions, the plurality of bottom connectors being arranged in a different phase from the first strut in the circumferential direction of the expandable body. This results in a portion extending in the circumferential direction between the bottom connectors and the first strut that are arranged in a different phase, making it easier for a force to act in a direction widening the branching angle and making it difficult for a compressive force to be converted into an expansive force.

[0018] The energy transmission element arrangement section may be provided on the proximal upright section, and the buffer section may be provided only on the distal expansion section, thereby ensuring that the energy transmission element is pressed against tissue when the expansion body is compressed.

[0019] The second expansion section may have a plurality of proximal strut structures extending radially outward from the distal end of the shaft in the distal direction to form the proximal expansion section, and each of the proximal strut structures may have a third strut arranged in the same phase as the plurality of energy transfer element arrangement sections in the circumferential direction of the expandable body, extending from the distal end of the shaft to the proximal apex generally parallel to the axis of the expandable body as viewed from the outside in the radial direction. This allows the energy transfer elements to be reliably pressed against tissue when the expandable body is compressed.

[0020] The second expansion section may have a plurality of secondary struts connecting circumferentially adjacent third struts of the plurality of proximal strut structures, each of the plurality of secondary struts having at least one support strut with two joints joined to two circumferentially adjacent third struts of the plurality of third struts, and each of the plurality of support struts may be formed longer than the linear distance between the two joints. This allows the support struts to prevent the proximal strut structure from twisting in the circumferential direction when subjected to a compressive force when pressing the energy transmission element against tissue. This makes it less likely that the force pressing the energy transmission element against tissue will dissipate, allowing the medical device to effectively press the energy transmission element against biological tissue.

[0021] The second expansion section may include a plurality of proximal strut structures that extend radially outward from the distal end of the shaft section toward the distal end and form the proximal expansion section, each of the plurality of proximal strut structures including a third section including a third strut extending from the distal end of the shaft section substantially parallel to the axis of the expandable body when viewed from the radially outward side, and a fourth section including two fourth struts that bifurcate from the distal end of the third section substantially along the circumferential direction of the expandable body and connected to the proximal apex, wherein the fourth section functions as the buffer that relieves the compressive force by curving so as to increase the branching angle between the two branching fourth struts. By curving so as to increase the branching angle between the two branching fourth struts, the fourth section of the proximal strut structure relieves the compressive force and can prevent the expandable body from expanding excessively radially outward.

[0022] The fourth section may have multiple junctions near the proximal apex where each of the two fourth struts joins one of the two fourth struts of another circumferentially adjacent fourth section. This allows the expandable body to have adjacent proximal strut structures 0 supporting each other in the circumferential direction, making it less likely to twist during expansion. This allows the expandable body to appropriately expand appropriate locations of biological tissue, enabling appropriate cauterization. Another aspect of the medical device according to the present invention that achieves the above object comprises an expansion body that is radially expandable and contractible and has a tip portion including a force receiving portion, a long shaft portion having a tip portion to which the base end of the expansion body is fixed, a plurality of energy transmission elements provided along the expansion body, and a traction shaft that is disposed inside the shaft portion, protrudes from the tip portion of the shaft portion, is connectable to the force receiving portion of the expansion body, and is slidable relative to the shaft portion, wherein the expansion body comprises a tip side expansion portion that extends radially outward from the force receiving portion in the base end direction, a first expansion section including a distal apex portion that is arranged on the proximal side of the distal expansion section and that is curved convexly outward in the radial direction; a base expansion section that extends radially outward from the distal end of the shaft section toward the distal direction; a second expansion section including a proximal apex portion that is arranged on the distal side of the proximal expansion section and that is curved convexly outward in the radial direction; and a recess that is recessed radially inward and extends to connect the proximal apex portion and the distal apex portion, and that defines an accepting space that can accept biological tissue when the expandable body is expanded, a distal-side upright portion extending radially outward from the base end of the bottom portion to the distal-side apex, and a proximal-side upright portion extending radially outward from the base end of the bottom portion to the proximal-side apex, the proximal-side upright portion being arranged at substantially equal intervals in the circumferential direction of the expandable body and having a plurality of energy transfer element arrangement portions on which the plurality of energy transfer elements are arranged, the distal-side upright portion having a plurality of opposing portions opposing the plurality of energy transfer elements when the expandable body is expanded, and the traction shaft sliding in the proximal direction relative to the shaft portion causes the plurality of energy transfer elements to be arranged. The expansion body is configured to apply a compressive force along the axis of the shaft portion via the force receiving portion so that the energy transfer element arrangement portion and the multiple opposing portions approach each other, and the expansion body has a buffer portion that is arranged in the first expansion portion and is configured to mitigate the compressive force by deforming in a direction different from the direction from the force receiving portion toward the distal apex along the distal expansion portion, and each of the multiple energy transfer element arrangement portions extends from the base end of the bottom portion to the proximal apex approximately parallel to the axis of the expansion body when viewed from the radial outside. The recess has a plurality of bottom connecting portions at the bottom that connect each pair of the plurality of energy transfer element arrangement portions and the plurality of opposing portions, and each of the plurality of opposing portions has a plurality of tip-side standing struts that branch into two while widening toward the tip, and a plurality of back support portions arranged in a row from the side closer to the bottom to the side closer to the tip-side apex, and each of the plurality of back support portions connects two of the tip-side standing struts that branch from each of the plurality of bottom connecting portions, and may be curved so that the portion between both ends connected to the two tip-side standing struts protrudes toward the tip-side apex. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side view showing the overall configuration of a medical device according to an embodiment of the present invention. [Figure 2] FIG. 10 is an enlarged perspective view of the medical device near the expandable body. [Figure 3] FIG. 1 is a side view showing the distal end of a medical device. [Figure 4] FIG. 2 is a front view of the medical device as seen from the distal end side. [Figure 5]FIG. 10 is a schematic diagram showing a state in which an expandable body is placed in a through-hole in the atrial septum. [Figure 6] FIG. 10 is a cross-sectional view showing the state in which the balloon is inserted into the atrial septum. [Figure 7] FIG. 10 is a cross-sectional view showing the state in which the tip of the medical device is inserted into the atrial septum. [Figure 8] FIG. 10 is a cross-sectional view showing the state in which the expansion body is placed in the atrial septum. [Figure 9] 10 is a cross-sectional view showing a state in which multiple energy transmission elements arranged in the recess of the expandable body are in close contact with biological tissue. FIG. [Figure 10] 1 is a flowchart illustrating a shunt formation method. [Figure 11] FIG. 10 is a side view showing the expansion body of the first modified example. [Figure 12] FIG. 10 is a front view showing the expansion body of the first modified example. [Figure 13] FIG. 10 is a side view showing an expansion body of a second modified example. [Figure 14] FIG. 10 is a front view showing an expansion body of a second modified example. [Figure 15] FIG. 10 is a side view showing an expansion body of a third modified example. [Figure 16] FIG. 10 is a front view showing an expansion body of a third modified example. [Figure 17] FIG. 10 is a side view showing an expansion body of a fourth modified example. [Figure 18] FIG. 11 is a side view showing a state in which a compressive force in the axial direction is applied to the expandable body of the fourth modified example. [Figure 19] FIG. 13 is a side view showing an expansion body of a fifth modified example. [Figure 20] FIG. 13 is a side view showing an expansion body of a sixth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensional proportions in the drawings may be exaggerated for convenience of explanation and may differ from the actual proportions. In addition, in this specification, the side of a medical device that is inserted into a body lumen will be referred to as the "distal side," and the side that is operated will be referred to as the "proximal side."

[0025] As shown in Figure 5, the medical device 10 of this embodiment is configured to expand a through hole Hh formed in the atrial septum HA of a patient's heart H, and to perform a maintenance procedure to maintain the expanded through hole Hh at that size.

[0026] 1, a medical device 10 according to this embodiment has a long section 20 extending from the base end to the tip, an expansion body 21 provided at the tip end of the long section 20, and an operation section 23 connected to the base end of the long section 20. The expansion body 21 is provided with an energy transmission element 22 (electrode section) for performing the maintenance treatment described above.

[0027] As shown in Figures 1 to 3, the long portion 20 has a shaft portion 31 that holds the expansion body 21 at its tip, an outer tube 30 that houses the shaft portion 31, a traction shaft 33, and a traction portion 35 that is fixed to the tip of the traction shaft 33.

[0028] The shaft portion 31 is a long tubular body extending from the operation portion 23 to the expansion body 21. The base end of the shaft portion 31 is fixed to the tip end of the operation portion 23. The tip end of the shaft portion 31 is fixed to the base end of the expansion body 21.

[0029] The outer tube 30 is a long tubular body that covers the shaft portion 31 and is movable back and forth in the axial direction (toward the axis of the long portion 20) relative to the shaft portion 31. The outer tube 30 can house the contracted expandable body 21 inside when it is moved toward the distal end of the long portion 20. When the expandable body 21 is housed inside the outer tube 30, the expandable body 21 can be exposed by moving the outer tube 30 toward the proximal end.

[0030] The traction shaft 33 is a long tubular body disposed inside the shaft portion 31, and is movable back and forth in the axial direction relative to the shaft portion 31. The traction shaft 33 protrudes toward the distal end from the distal end of the shaft portion 31, and protrudes toward the distal end from the distal end of the expandable body 21. The distal end of the traction shaft 33, which is positioned distal to the expandable body 21, is fixed to the traction portion 35. The proximal end of the traction shaft 33 is led out toward the proximal end from the operation portion 23. A guidewire lumen is formed inside the traction shaft 33 along the axial direction, and a guidewire 11 (see FIGS. 5 to 7) can be inserted therethrough.

[0031] The traction portion 35 is an annular member fixed to the outer peripheral surface of the tip of the traction shaft 33, and protrudes radially outward from the outer peripheral surface of the traction shaft 33. The traction portion 35 is not fixed to the expansion body 21. The outer diameter of the traction portion 35 is larger than the inner diameter of the tip of the expansion body 21. Therefore, the traction portion 35 abuts against the tip of the expansion body 21 from the tip side, and pulls the expansion body 21 toward the base end, thereby applying a compressive force to the expansion body 21 that compresses it along the axial direction of the shaft portion 31.

[0032] The operation unit 23 has a housing 40 that is held by the surgeon, a dial 41 that can be rotated by the surgeon, and a conversion mechanism 42 that converts the rotation of the dial 41 into movement in the axial direction. The dial 41 is rotatably connected to the housing 40. A portion of the dial 41 is exposed to the outside through an opening in the housing 40 so that it can be operated by the surgeon. The traction shaft 33 is held by the conversion mechanism 42 inside the operation unit 23. The conversion mechanism 42 can move the held traction shaft 33 forward and backward along the axial direction as the dial 41 rotates. As the conversion mechanism 42, for example, a rack and pinion mechanism can be used.

[0033] As shown in Figures 2 to 4, the expansion body 21 has a force receiving portion 51 arranged at the tip of the expansion body 21, a base end connecting portion 52 arranged at the base end of the expansion body 21, a first expansion portion 53 connected to the force receiving portion 51, a second expansion portion 54 connected to the base end connecting portion 52, and a recess 55 arranged between the first expansion portion 53 and the second expansion portion 54.

[0034] The force receiving portion 51 is annular and can receive a force directed toward the base end from the traction portion 35 arranged on the tip side. The base end connecting portion 52 is annular and is fixed to the tip end of the shaft portion 31.

[0035] The first extension portion 53 has a tip extension portion 56 that extends radially outward from the force receiving portion 51 toward the base end, and a tip apex portion 57 that is arranged on the base end side of the tip extension portion 56 and is curved convexly radially outward.

[0036] The first extension portion 53 extends radially outward from the force-receiving portion 51 in the proximal direction and has a plurality of distal strut structures 60 that form a distal extension portion 56 .

[0037] Each of the multiple tip strut structures 60 has a first section 61 extending from the force receiving portion 51 toward the base end, and a second section 62 extending from the base end of the first section 61 toward the base end and connected to the tip apex 57.

[0038] Each first section 61 has a first strut 63 extending from the force receiving portion 51 substantially parallel to the axis of the expansion body 21 when viewed from the outside in the radial direction.

[0039] Each second section 62 has a plurality of second struts 64 that branch into two and expand in the circumferential direction of the expandable body 21 while moving proximally from the base end of each first strut 63, first and second junctions 65 and 66 connected to the base ends of the second struts 64, and an auxiliary curved portion 67 that functions as a buffer. The first and second junctions 65 and 66 are arranged alternately at approximately equal intervals in the circumferential direction of the expandable body 21 when expanded. Each of the first and second junctions 65 and 66 is formed by the junction of two second struts 64 that branch from two circumferentially adjacent first struts 63 located on the distal side and extend toward each other. Twelve first struts 63 are provided in the expandable body 21, which is twice the number of energy transmission elements 22. The expansion body 21 is provided with 24 second struts 64, which is twice the number of first struts 63 and four times the number of energy transmission elements 22. The numbers of first struts 63 and second struts 64 can be changed as appropriate.

[0040] Each first confluence 65 is connected to the distal end apex 57, which is arranged in the same phase as the energy transmission element 22 in the circumferential direction of the expandable body 21, via an auxiliary curved portion 67 that functions as a buffer. When viewed from the outside in the radial direction, the auxiliary curved portion 67 is curved in a wave-like manner, folding back multiple times.

[0041] Each second confluence 66 is connected to a tip apex 57 arranged at a different phase in the circumferential direction of the expansion body 21 relative to the energy transfer element 22, via a connecting strut 68 that extends approximately parallel to the axis of the expansion body 21 when viewed from the radial outside.

[0042] In the natural state, two second struts 64 branching off from the base end of each first strut 63 are connected at a first branching angle α. In the natural state, two second struts 64 aligned in the circumferential direction are connected to a first junction 65 or a second junction 66 at a second branching angle β.

[0043] The distal apex 57 has a plurality of first distal apexes 69 connected to the auxiliary bending section 67 and a plurality of second distal apexes 70 connected to the connecting struts 68. The first distal apexes 69 and the second distal apexes 70 are arranged alternately at approximately equal intervals in the circumferential direction of the expandable body 21 when expanded.

[0044] When the expandable body 21 is expanded, the recess 55 is recessed radially inward and extends to connect the base end apex 59 and the tip end apex 57. The recess 55 defines a receiving space 74 that can receive biological tissue when the expandable body 21 is expanded.

[0045] The recess 55 has a bottom portion 71 located at the radially innermost position, a tip-side upright portion 72 extending radially outward from the tip of the bottom portion 71 to the tip-side apex 57, and a base-side upright portion 73 extending radially outward from the base end of the bottom portion 71 to the base-side apex 59.

[0046] The recess 55 has a plurality of concave strut structures 80 connected to the plurality of distal strut structures 60 via distal apexes 57. Each of the plurality of concave strut structures 80 has an energy transfer element arrangement portion 81 arranged on the base end upright portion 73 and an opposing portion 82 arranged on the distal end upright portion 72, and has a bottom connecting portion 83 on the bottom 71 that connects the pair of energy transfer element arrangement portion 81 and opposing portion 82. Each bottom connecting portion 83 is arranged at a different phase from the first strut 63 in the circumferential direction of the expandable body 21.

[0047] The plurality of energy transfer element arrangement sections 81 are arranged at approximately equal intervals in the circumferential direction of the expandable body 21. The energy transfer elements 22 are arranged on the surfaces that form the inner sides of the recesses 55 of the respective energy transfer element arrangement sections 81.

[0048] Each of the opposing portions 82 faces a corresponding one of the energy transmission elements 22 when the expandable body 21 is expanded. Each of the opposing portions 82 has a plurality of bifurcated distal upright struts 84 that extend from the distal ends of the respective bottom connecting portions 83 and extend generally along the circumferential direction of the expandable body 21, and a plurality of back support portions 85. Each of the second distal apexes 70 is formed by the merging of two distal upright struts 84 that extend toward each other from two circumferentially adjacent bottom connecting portions 83 disposed on the proximal end side. The multiple back support portions 85 connect the two distal upright struts 84 that branch from each of the bottom connecting portions 83. The multiple back support portions 85 are arranged side by side from the side closer to the bottom 71 to the side closer to the distal apex 57. Each of the back support portions 85 is curved such that the portion between the ends connected to the two distal upright struts 84 protrudes toward the distal apex 57. Each backrest portion 85 is more likely to bend on the side closer to the distal apex 57, with both ends connected to the distal standing struts 84 as fulcrums. Therefore, the backrest portion 85 can bend due to a distal-directed force received from the energy transfer elements 22 arranged on the proximal standing portion 73. Therefore, the biological tissue sandwiched between the energy transfer elements 22 and the backrest portion 85 can be brought into close contact with the energy transfer elements 22. Of the multiple backrest portions 85 forming each opposing portion 82, the backrest portion 85 closest to the distal apex 57 is connected to the first distal apex 69 at a portion protruding toward the distal apex 57. The number of backrest portions 85 forming each opposing portion 82 is not particularly limited.

[0049] The second expansion portion 54 has a base-end expansion portion 58 that extends radially outward from the base-end connecting portion 52 toward the tip, and a base-end apex portion 59 that is located at the tip side of the base-end expansion portion 58 and is convexly curved radially outward.

[0050] The proximal expansion section 58 has multiple proximal strut structures 90. Each proximal strut structure 90 and the multiple energy transfer element arrangement sections 81 are arranged in the same phase in the circumferential direction of the expandable body 21. Each of the multiple proximal strut structures 90 has multiple third struts 91 extending from the distal end of the shaft section 31 to the proximal apex 59, approximately parallel to the axis of the expandable body 21 when viewed from the outside in the radial direction, and multiple secondary struts 92 connecting adjacent third struts 91 in the circumferential direction. Each secondary strut 92 has two support struts 93 joined at joints 94 to each of two adjacent third struts 91 in the circumferential direction. The two support struts 93 are connected at an angle between the two joints 94. In a natural state, the two connected support struts 93 are connected at a connection angle γ of less than 180 degrees. Therefore, each secondary strut 92 is formed to be longer than the linear distance between the two joints 94. For this reason, even if the distance between the two joints 94 becomes longer when the expandable body 21 expands, the secondary strut 92 can continue to support the two third struts 91 while changing the connection angle γ between the two support struts 93 that make up the secondary strut 92. For this reason, the compressive force applied by the traction shaft 33 allows the expandable body 21 to expand while spreading the third struts 91 at approximately equal intervals.

[0051] It is preferable that the distance between the base-side upright portion 73 and the tip-side upright portion 72 is somewhat larger in the axial direction on the outer side than on the inner side in the radial direction when the expansion section is expanded. This makes it easy to place biological tissue between the base-side upright portion 73 and the tip-side upright portion 72 from the outer side in the radial direction.

[0052] When the expansion section is expanded, the energy transmission element 22 is disposed on the surface facing the distal end of the proximal upright portion 73. Because the energy transmission element 22 is provided on the proximal upright portion 73, when the recess 55 clamps the atrial septum HA, energy from the energy transmission element 22 is transmitted to the atrial septum HA from the right atrium side. Note that if the energy transmission element 22 is provided on the distal upright portion 72, energy from the energy transmission element 22 is transmitted to the atrial septum HA from the left atrium side.

[0053] The energy transfer elements 22 are configured, for example, with bipolar electrodes that receive electrical energy from an external energy supply device (not shown). In this case, electricity is passed between the energy transfer elements 22 arranged in each energy transfer element 22 arrangement section. The energy transfer elements 22 and the energy supply device are connected by a conductor (not shown) covered with an insulating coating material. The conductor is led out via the elongated portion 20 and the operating portion 23 and connected to the energy supply device.

[0054] Alternatively, the energy transfer element 22 may be configured as a monopolar electrode. In this case, current is passed between the energy transfer element 22 and a return electrode plate prepared outside the body. Alternatively, the energy transfer element 22 may be a heating element (electrode chip) that receives high-frequency electrical energy from an energy supply device and generates heat. In this case, current is passed between the energy transfer elements 22 disposed in each wire portion. Furthermore, the energy transfer element 22 may be configured as an element capable of applying energy to the through-hole Hh, such as microwave energy, ultrasonic energy, coherent light such as a laser, a heated fluid, a cooled fluid, a device that exerts a heating or cooling effect using a chemical medium, a device that generates frictional heat, a heater equipped with an electric wire, or the like, and the specific form is not particularly limited.

[0055] In this embodiment, the energy transfer element 22 is provided on the base end standing portion 73 and the back support portion 85 is provided on the tip end standing portion 72, but it is also possible to provide the energy transfer element 22 on the tip end standing portion 72 and the back support portion 85 on the base end standing portion 73.

[0056] The expandable body 21 is formed integrally, for example, by cutting out from a cylinder. The struts forming the expandable body 21 may have a thickness of 50 to 500 μm and a width of 0.3 to 2.0 mm, for example. However, the struts forming the expandable body 21 may have dimensions outside these ranges. Furthermore, the shape of the struts is not particularly limited, and may have, for example, a circular cross-sectional shape or other cross-sectional shapes.

[0057] The expandable body 21 can be made of a metal material. Examples of such metal materials include titanium alloys (Ti-Ni, Ti-Pd, Ti-Nb-Sn, etc.), copper alloys, stainless steel, β-titanium steel, and Co-Cr alloys. It is preferable to use alloys with spring properties, such as nickel-titanium alloys. However, the material of the wire portion is not limited to these, and other materials may also be used.

[0058] The outer cylinder 30 and shaft portion 31 of the long portion 20 are preferably formed from a material having a certain degree of flexibility. Examples of such materials include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, and 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, and latex rubber.

[0059] The traction shaft 33 and the traction part 35 can be formed of 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, a resin material with relatively high rigidity, etc. Alternatively, the above may be coated with a resin material such as polyvinyl chloride, polyethylene, polypropylene, an ethylene-propylene copolymer, or a fluororesin.

[0060] Next, a shunt formation method using the medical device 10 according to this embodiment will be described with reference to the flowchart shown in Fig. 10. The shunt formation method is performed on a patient suffering from heart failure (left-sided heart 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 in the left atrium HLa increases due to hypertrophy of the myocardium of the left ventricle of the heart H and increased stiffness.

[0061] The shunt formation method of this embodiment includes the steps of: forming a through-hole Hh in the atrial septum HA (S1); placing an expandable body 21 in the through-hole Hh (S2); receiving biological tissue in the receiving space 74 (S3); expanding the diameter of the through-hole Hh using the expandable body 21 (S4); checking the hemodynamics near the through-hole Hh (S5); performing maintenance treatment to maintain the size of the through-hole Hh (S6); and checking the hemodynamics near the through-hole Hh after the maintenance treatment has been performed (S7).

[0062] When forming the through-hole Hh, the surgeon delivers an introducer, which is a combination of a guiding sheath and a dilator, to the vicinity of the interatrial 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 11. The surgeon can insert the guidewire 11 into the dilator and deliver the introducer along the guidewire 11. The insertion of the introducer and the guidewire 11 into the living body can be performed by a known method, such as using an introducer for introducing blood vessels.

[0063] In step S1, the surgeon passes a puncture device (not shown) from the right atrium HRa side toward the left atrium HLa side to form a through-hole Hh in the fossa ovalis of the interatrial septum HA. For example, a device such as a sharp-tipped wire can be used as the puncture device. The puncture device is inserted through a dilator and delivered to the interatrial septum HA. After removing the guidewire 11 from the dilator, the puncture device can be delivered to the interatrial septum HA in place of the guidewire 11.

[0064] Next, the surgeon delivers the balloon catheter 150 to the vicinity of the atrial septum HA along the pre-inserted guide wire 11. As shown in Fig. 6, the balloon catheter 150 has a balloon 152 at the distal end of a shaft portion 151. Once the balloon 152 is positioned in the atrial septum HA, it is expanded radially to expand the through-hole Hh.

[0065] In step S2, as shown in Fig. 7, the medical device 10 is delivered to the vicinity of the atrial septum HA along the pre-inserted guide wire 11. At this time, the distal end of the medical device 10 penetrates the atrial septum HA and reaches the left atrium HLa. During the insertion of the medical device 10, the expandable body 21 is housed in the outer tube 30.

[0066] Next, in step S3, the outer tube 30 is moved toward the proximal end to expose the expandable body 21. As a result, as shown in Fig. 8, the diameter of the expandable body 21 expands, and the recess 55 is positioned in the through-hole Hh in the atrial septum HA, receiving the biological tissue surrounding the through-hole Hh in the receiving space 74. The through-hole Hh is maintained in an expanded state by the expandable body 21.

[0067] In step S4, with the atrial septum HA received in the receiving space 74 of the recess 55, the surgeon operates the operating unit 23 to move the traction shaft 33 toward the proximal end, thereby sandwiching the biological tissue between the recess 55 of the expansion body 21, as shown in FIG. 9 . The thickness of the atrial septum HA (biological tissue) varies from individual to individual, and it can be thick or thin. When the atrial septum HA is thick, the second section 62 can bend so that the first branching angle α and the second branching angle β of the second strut 64 increase when a compressive force acts on the expansion body 21 due to traction by the traction shaft 33. That is, the second section 62, which serves as a buffer, deforms in a direction different from the direction from the force-receiving portion 51 toward the distal apex 57. This reduces the compressive force received by the traction shaft 33 on the expansion body 21, thereby preventing the expansion body 21 from expanding too far outward in the radial direction. Furthermore, the auxiliary bending portion 67, located between the distal apex 57 and the first confluence portion 65, can be deformed in various directions. Therefore, when a compressive force acts on the expandable body 21 due to the traction of the traction shaft 33, the auxiliary bending portion 67 also functions as a buffer that deforms in a direction different from the direction from the force-receiving portion 51 toward the distal apex 57, thereby further reducing the compressive force. Similarly, when a compressive force acts on the expandable body 21 due to the traction of the traction shaft 33, the secondary struts 92 of the proximal strut structure 90 also deform in a direction different from the direction from the proximal connecting portion 52 toward the proximal apex 59. That is, the two support struts 93 constituting each secondary strut 92 deform while increasing the connecting angle γ, thereby functioning as a buffer. Therefore, the deformation of each buffer suppresses the variation in the amount of radial outward expansion of the expandable body 21 depending on whether the biological tissue is thick or thin. Therefore, regardless of whether the atrial septum HA is thick or thin, the through-hole Hh can be made an appropriate size without being too large or too small.

[0068] Once the expandable body 21 has been placed in the through-hole Hh, hemodynamics is confirmed in step S5. As shown in FIG. 5, the surgeon delivers the hemodynamic confirmation device 100 to the right atrium HRa via the inferior vena cava Iv. A known echo catheter, for example, can be used as the hemodynamic confirmation device 100. The surgeon can display the echo image acquired by the hemodynamic confirmation device 100 on a display or other display device, and can confirm the amount of blood passing through the through-hole Hh based on the display results.

[0069] Next, in step S6, the surgeon performs a maintenance treatment to maintain the size of the through-hole Hh. In the maintenance treatment, high-frequency energy is applied to the edge of the through-hole Hh through the energy transmission element 22, thereby cauterizing (heating and cauterizing) the edge of the through-hole Hh with the high-frequency energy.

[0070] When the biological tissue near the edge of the through-hole Hh is cauterized through the energy transmission element 22, a denatured portion is formed near the edge where the biological tissue is denatured. Because the biological tissue in the denatured portion loses its elasticity, the through-hole Hh can maintain the shape it had when expanded by the expandable body 21. The through-hole Hh is maintained at an appropriate size and shape by the expandable body 21, which has a buffer portion, during cauterization.

[0071] After the maintenance treatment, the hemodynamics is checked again in step S7, and if the amount of blood passing through the through-hole Hh is the desired amount, the surgeon reduces the diameter of the expandable body 21, stores it in the outer tube 30, and removes it from the through-hole Hh. Then, the entire medical device 10 is removed from the living body, completing the treatment.

[0072] As described above, the medical device 10 according to this embodiment comprises an expansion body 21 that is radially expandable and contractible and has a tip end including a force receiving portion 51, a long shaft portion 31 that has a tip end to which the base end of the expansion body 21 is fixed, a plurality of energy transmission elements 22 (electrode portions) that are provided along the expansion body 21, and a traction shaft 33 that is disposed inside the shaft portion 31, protrudes from the tip end of the shaft portion 31, is connectable to the force receiving portion 51 of the expansion body 21, and is slidable relative to the shaft portion 31. The expansion body 21 extends radially outward from the force receiving portion 51 toward the base end. a first expansion section (53) including a distal expansion section (56) extending radially outward from the distal end of the shaft section (31) toward the distal end, and a distal apex (57) arranged on the proximal side of the distal expansion section (56) and curved in a convex shape facing radially outward; a second expansion section (54) including a base expansion section (58) extending radially outward from the distal end of the shaft section (31) toward the distal end, and a base apex (59) arranged on the distal side of the base expansion section (58) and curved in a convex shape facing radially outward; and a recess (55) recessed radially inward and extending to connect the base apex (59) and the distal apex (57), defining a receiving space (74) capable of receiving biological tissue when the expandable body (21) is expanded. The recess 55 has a bottom 71 located at the innermost position in the radial direction, a tip-side upright portion 72 extending radially outward from the tip of the bottom 71 to a tip-side apex 57, and a base-side upright portion 73 extending radially outward from the base end of the bottom 71 to a base-side apex 59. Either the tip-side upright portion 72 or the base-side upright portion 73 has a plurality of energy transfer element arrangement portions 81 in which a plurality of energy transfer elements are arranged at approximately equal intervals in the circumferential direction of the expandable body 21, and the other of the tip-side upright portion 72 and the base-side upright portion 73 faces each of the plurality of energy transfer elements when the expandable body 21 is expanded. The traction shaft 33 is configured to apply a compressive force along the axis of the shaft portion 31 to the expansion body 21 via the force receiving portion 51 so that the plurality of energy transmission element arrangement portions 81 and the plurality of opposing portions 82 approach each other by sliding relative to the shaft portion 31 in the proximal direction, and the expansion body 21 is configured to have a buffer portion disposed in the first expansion portion 53 and configured to relieve the compressive force by deforming in a direction different from the direction from the force receiving portion 51 toward the distal end apex 57 along the distal end side expansion portion 56, or a buffer portion disposed in the second expansion portion 54,The buffer portion is configured to relieve compressive force by deforming along the proximal expansion portion 58 in a direction different from the direction from the proximal end of the expandable body 21 toward the proximal apex 59.

[0073] In the medical device 10 configured as described above, when a compressive force acts on the expandable body 21 due to traction by the traction shaft 33, the buffer portion deforms in a direction different from the direction from the force-receiving portion 51 toward the distal apex 57 or the direction different from the direction from the base end of the expandable body 21 toward the proximal apex 59, thereby alleviating the compressive force and preventing the expandable body 21 from expanding excessively radially outward. This reduces variation in the amount of radially outward expansion of the expandable body 21 when the biological tissue received in the receiving space 74 of the expandable body 21 is thick or thin. Therefore, the medical device 10, when passed through a hole penetrating biological tissue, prevents variation in the amount of radial expansion of the expandable body 21, which expands radially outward due to a compressive force, caused by variations in the thickness of the biological tissue. Therefore, the medical device 10 is less susceptible to variations in the thickness of biological tissue, prevents excessive expansion of holes in biological tissue, and enables safe and appropriate cauterization.

[0074] Furthermore, the first expansion section 53 has a plurality of distal strut structures 60 that extend radially outward from the force receiving section 51 towards the base end and form a distal expansion section 56, and each of the distal strut structures 60 has a curved section (second strut 64) that serves as a buffer section and can bend in a direction different from the direction from the force receiving section 51 towards the distal apex 57 along each distal strut structure 60. This allows the buffer section to be realized with a simple structure.

[0075] Each of the multiple distal strut structures 60 has a first section 61 including a first strut 63 extending from the force-receiving portion 51 generally parallel to the axis of the expandable body 21 when viewed from the outside in the radial direction, and a second section 62 including two second struts 64 bifurcating from the base end of the first section 61 generally along the circumferential direction of the expandable body 21 and connected to the distal apex 57, the second section 62 functioning as a buffer that alleviates compressive forces by curving so as to increase the first branch angle α and the second branch angle β formed by the two branched second struts 64. As a result, the second section 62 of the distal strut structure 60 is curved so as to increase the first branch angle α and the second branch angle β formed by the two branched second struts 64, thereby alleviating compressive forces and preventing the expandable body 21 from expanding too far radially outward.

[0076] Additionally, the second section 62 has a plurality of first junctions 65 and second junctions 66 near the distal apex 57, where each of two second struts 64 joins one of two second struts 64 of another circumferentially adjacent second section 62. This allows the adjacent distal strut structures 60 of the expandable body 21 to support each other circumferentially, making it less likely to twist during expansion. This allows the expandable body 21 to appropriately expand appropriate positions of biological tissue, enabling appropriate cauterization.

[0077] The second section 62 also has an auxiliary curved portion 67 that functions as a buffer between the distal end apex 57, which is arranged in the same phase as the energy transfer element arrangement portion 81 or the opposing portion 82 in the circumferential direction of the expandable body 21, and the first confluence portions 65. As a result, the auxiliary curved portion 67 deforms to further reduce the compressive force, making it more difficult for the compressive force to be converted into an expansion force.

[0078] Furthermore, the multiple distal strut structures 60 have twice the number of first sections 61 and junctions (first junctions 65 and second junctions 66) as the multiple energy transfer elements 22 (electrode portions), and the junctions alternate in the circumferential direction of the expandable body 21, with the first junctions 65 arranged in the same phase as the multiple energy transfer element arrangements 81 and multiple opposing portions 82 and the second junctions 66 arranged in a different phase from the multiple energy transfer element arrangements 81 and multiple opposing portions 82. This allows the expandable body 21 to have a configuration in which adjacent distal strut structures 60 support each other in the circumferential direction, making it less likely to twist during expansion. This allows the expandable body 21 to appropriately expand appropriate positions in biological tissue, enabling appropriate cauterization.

[0079] Furthermore, the medical device 10 has an auxiliary bending portion 67 that functions as a buffer portion between the first confluence portion 65 and the distal apex portion 57. As a result, the auxiliary bending portion 67 deforms to further reduce the compressive force, making it more difficult for the compressive force to be converted into an expansive force.

[0080] The recess 55 also has a concave strut structure 80 that is connected to the distal strut structure 60 via a distal apex 57 and defines a distal upright portion 72, a proximal upright portion 73, and a bottom 71, and the concave strut structure 80 has a plurality of bottom connectors 83 at the bottom 71 that connect each pair of a plurality of energy transfer element arrangement portions 81 and a plurality of opposing portions 82, and the plurality of bottom connectors 83 are arranged in a different phase from the first struts 63 in the circumferential direction of the expandable body 21. As a result, a portion extending in the circumferential direction exists between the bottom connectors 83 and the first struts 63 that are arranged in a different phase, making it easier for a force to act in a direction widening the branching angle and making it difficult for a compressive force to be converted into an expansive force.

[0081] Furthermore, the energy transmission element arrangement section 81 is provided on the base-side standing section 73, and the buffer section is provided only on the tip-side expansion section 56. This allows the second expansion section 54 to effectively transmit the compressive force when the expansion body 21 is compressed, thereby ensuring that the energy transmission element is pressed against the tissue.

[0082] The second expansion section 54 has a plurality of base-side strut structures 90 that extend radially outward from the tip of the shaft section 31 in the distal direction and form the base-side expansion section 58, and each of the base-side strut structures 90 has a third strut 91 that is arranged in the same phase as the plurality of energy transmission element arrangement sections 81 in the circumferential direction of the expandable body 21 and extends from the tip of the shaft section 31 to the base-side apex 59 substantially parallel to the axis of the expandable body 21 as viewed from the outside in the radial direction. This allows the second expansion section 54 to effectively transmit compressive force when the expandable body 21 is compressed, ensuring that the energy transmission elements are pressed against the tissue.

[0083] Furthermore, the second expansion section 54 has a plurality of secondary struts 92 connecting circumferentially adjacent third struts 91 of the plurality of second strut 64 structures, and each of the plurality of secondary struts 92 has at least one support strut 93 having two joints 94 joined to each of two circumferentially adjacent third struts 91 of the plurality of third struts 91, and each of the plurality of support struts 93 is formed longer than the linear distance between the two joints 94. This enables the support strut 93 to prevent the second strut 64 structure from twisting in the circumferential direction when subjected to a compressive force when pressing the energy transmission elements against tissue. Therefore, in the medical device 10, the force pressing the energy transmission elements against tissue is less likely to dissipate, allowing the energy transmission elements to be pressed effectively against biological tissue.

[0084] The present invention also provides a shunt formation method. The shunt formation method includes inserting the above-described medical device 1010 into the right atrium HRa from the inferior vena cava Iv, inserting the contracted expandable body 21 into a hole formed in the fossa ovalis, expanding the expandable body 21 within the hole, placing biological tissue surrounding the hole in the receiving space 74 defined by the recess 55, and sliding the traction shaft 33 in the proximal direction relative to the shaft portion 31, thereby compressing the expandable body 21 so that the distal upright portion 72 and the proximal upright portion 73 of the recess 55 approach each other, and expanding the buffer portion 21 in a direction different from the direction from the force-receiving portion 51 toward the distal apex 57 along the distal expansion portion 56. or by deforming the buffer section disposed in the second expansion section 54 in a direction different from the direction from the base end of the expansion body 21 toward the base end apex 59 along the base end expansion section 58, the compressive force is alleviated, while an energy transmission element disposed along the tip end upright section 72 or the base end upright section 73 of the recess 55 so as to face the recess 55 is brought into close contact with the biological tissue, and the biological tissue disposed in the receiving space 74 is cauterized using the energy transmission element in close contact with the biological tissue so as to inhibit closure of the hole by natural healing.

[0085] In the shunt formation method configured as described above, when a compressive force acts on the expandable body 21 due to traction by the traction shaft 33, the buffer portion deforms in a direction different from the direction from the force-receiving portion 51 toward the distal apex 57 or from the proximal end of the expandable body 21 toward the proximal apex 59, thereby alleviating the compressive force. This prevents the expandable body 21 from expanding excessively radially outward. This reduces the variation in the amount of radially outward expansion of the expandable body 21 between thick and thin biological tissue. This shunt formation method therefore reduces the variation in the amount of radial expansion of the expandable body 21, which is expanded radially outward by a compressive force after being passed through a hole penetrating biological tissue, due to variations in the thickness of the biological tissue. This shunt formation method is therefore less susceptible to variations in the thickness of biological tissue, prevents excessive expansion of holes in biological tissue, and enables safe and appropriate cauterization.

[0086] 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 spirit of the present invention. Therefore, the location of the buffer section is not particularly limited as long as it is in the first or second expansion section. For example, as in a first modification shown in FIGS. 11 and 12 , the number of first struts 63 may be half that of the embodiment shown in FIGS. 1 to 4 , i.e., six, and the number of second struts 64 may be half that of the embodiment shown in FIGS. 1 to 4 . The first struts 63 are arranged in a different phase from the third struts 91, the energy transfer element placement section 81, the opposing section 82, and the energy transfer elements 22. The confluences where the second struts 64 converge are all first confluences 65, and the second confluences 66, connecting struts 68, and second distal apexes 70 shown in FIG. 3 may not be provided. An auxiliary curved section 67 is provided between the first confluence 65 and the first distal apex 69, but the auxiliary curved section 67 may not be provided.

[0087] 13 and 14, the number of first struts 63 may be three, which is one-fourth of the number of first struts 63 in the embodiment shown in FIGS. 1 to 4, and the number of second struts 64 (buffering sections) may be six, which is one-fourth of the number in the embodiment shown in FIGS. 1 to 4. The six second struts 64 branching from the three first struts 63 are connected to six auxiliary bending sections 67 (buffering sections) without gathering together. The auxiliary bending sections 67 do not need to be provided between the second struts 64 and the facing sections 82. The first struts 63 are arranged in a different phase from the third struts 91, the energy transfer element arrangement sections 81, the facing sections 82, and the energy transfer elements 22.

[0088] 1 to 4, the number of first struts 63 may be half, to six, and the number of second struts 64 (buffering sections) may be half, to twelve. The first struts 63 are arranged in the same phase as the third struts 91 and the energy transfer elements 22, and are connected to the force receiving sections 51 and auxiliary bending sections 67 (buffering sections). Each of the second struts 64 branches off midway along the length of the first struts 63. The junctions where the proximal portions of the second struts 64 converge are all second junctions 66, and no first junctions connected to the auxiliary bending sections 67 are provided. An auxiliary bending section 67 is provided between the first struts 63 and the first distal apex 69, but the auxiliary bending section 67 need not be provided.

[0089] Furthermore, as in a fourth modified example shown in FIG. 17 , each second strut 64 may have a curved portion 75 that protrudes radially outward in its natural state. Note that the protruding direction is not limited to the radially outward direction and may be, for example, the radially inward direction, the distal direction, the proximal direction, or the circumferential direction. When a compressive force acts on the expandable body 21, stress is concentrated in the curved portion 75, causing it to bend, as shown in FIG. 18 . The direction in which the curved portion 75 deforms is different from the direction from the force receiving portion 51 toward the distal apex 57 along the distal expansion portion 56. Therefore, when an axial compressive force acts on the expandable body 21, stress is concentrated in the curved portion 75, and the curved portion 75, which serves as a buffer, deforms in a direction (e.g., radially outward) different from the direction from the force receiving portion 51 toward the distal apex 57 of the expandable body 21. This alleviates the compressive force acting on the expandable body, thereby preventing the expandable body from expanding excessively radially outward.

[0090] Furthermore, the second strut 64 may not protrude in its natural state as in the fourth modified example, but may have a curved portion that is easily deformed in a direction other than the direction from the force-receiving portion 51 toward the tip-side apex 57 along the distal expansion portion 56 when an axial compressive force acts on the expandable body 21. Such a curved portion can be set by making the width of the second strut 64 (the circumferential length of the expandable body 21) smaller than the width of the other struts in the expandable body 21, or by making the thickness of the second strut 64 (the radial length of the expandable body 21) smaller than the thickness of the other struts in the expandable body 21.

[0091] Furthermore, as in a fifth modified example shown in FIG. 19, the second expansion section 54 on the base end side may have a plane-symmetrical structure substantially similar to the first expansion section 53 on the tip end side.

[0092] 20 , the second expansion section 54 on the proximal side may have a branched structure. The second expansion section 54 has a plurality of proximal strut structures 90 that extend radially outward from the distal end of the shaft section 31 toward the distal end and form a proximal expansion section 58. Each of the plurality of proximal strut structures 90 has a third section 95 including a third strut 91 that extends from the distal end of the shaft section 31 substantially parallel to the axis of the expandable body 21 when viewed from the outside in the radial direction, and a fourth section 96 that includes two fourth struts 97 that branch from the distal end of the third section 95 and extend substantially along the circumferential direction of the expandable body 21, and is connected to the proximal apex 59. The fourth section 96 functions as a buffer that absorbs compressive forces by curving so that the third branch angle θ between the two branched fourth struts 97 increases. The fourth section 97 of the base-end strut structure 90 is curved so as to increase the third branch angle θ formed by the two branched fourth struts 97, thereby alleviating the compressive force and preventing the expansion body 21 from expanding too far radially outward.

[0093] Additionally, the fourth section 96 has multiple third junctions 98 near the proximal apex 59, where each of two fourth struts 97 joins one of two fourth struts 97 of another circumferentially adjacent fourth section 96. This allows the adjacent proximal strut structures 90 of the expandable body 21 to support each other circumferentially, making the expandable body 21 less likely to twist during expansion. This allows the expandable body 21 to appropriately expand appropriate positions in biological tissue, enabling appropriate cauterization.

[0094] Furthermore, in step S1 of the shunt formation method described above, if the through hole Hh is sufficiently expanded by the balloon 152, in step S4, the through hole Hh may be essentially simply grasped by the expansion body 21 rather than being expanded by the expansion body 21.

[0095] The medical device 10 may also be a device that does not have the outer tube 30. In this case, a sheath corresponding to the outer tube 30 is separately prepared, and in step S2, the sheath is delivered in advance to the vicinity of the atrial septum HA along the guide wire 11 so that the distal end of the sheath reaches the left atrium HLa through the through-hole Hh in the atrial septum HA. Next, the expandable body 21 of the medical device 10 is inserted into the sheath from its proximal end, and the distal end of the expandable body 21 is delivered to the left atrium HLa through the through-hole Hh in the atrial septum HA, as in FIG. 7 .

[0096] Furthermore, step S4 of expanding the diameter of the through-hole Hh with the expandable body 21 or gripping the through-hole Hh with the expandable body 21 and step S5 of checking the hemodynamics near the through-hole Hh may be reversed. In this case, if the amount of blood passing through the through-hole Hh does not reach the desired amount in step S5, the surgeon moves the outer tube 30 toward the distal end to store the expandable body 21 inside the outer tube 30, and then removes the expandable body 21 together with the outer tube 30 from the through-hole Hh. Next, the through-hole Hh is expanded again using a balloon catheter having a balloon with an expansion diameter larger than the balloon 252 used in step S1, and the process returns to step S2.

[0097] This application is based on Japanese Patent Application No. 2021-114257 filed on July 9, 2021, the disclosures of which are incorporated by reference in their entirety. [Explanation of symbols]

[0098] 10 Medical Devices 21 Extension 22 Energy transmission element (electrode part) 31 Shaft section 33 Traction shaft 51 Force receiving part 53 First Extension 54 Second Extension 55 recess 56 Tip extension 57 Tip side apex 58 Proximal extension 59 Proximal apex 60 Tip strut structure 61 Section 1 62 Section 2 63 First Strut 64 Second strut (buffer part) 65 1st Confluence 66 2nd Confluence 67 Auxiliary curved section 71 Bottom 72 Tip side upright part 73 Proximal upright part 74 Receptive Space 80 Concave strut structure 81 Energy transfer element arrangement section 82 Opposing part 83 Bottom connection part 90 Base end strut structure 91 3rd strut 92 Secondary strut 93 Support strut 94 Joint 95 Third Section 96 Section 4 97 4th strut 98 3rd Confluence

Claims

1. an expansion body that is radially expandable and contractible and has a distal end portion including a force receiving portion; a long shaft portion having a distal end portion to which the proximal end of the expansion body is fixed; a plurality of energy transfer elements disposed along the extension body; a traction shaft disposed inside the shaft portion, protruding from the tip end of the shaft portion, connectable to the force receiving portion of the expansion body, and slidable relative to the shaft portion; Equipped with The expansion body is a first expansion portion including a distal expansion portion extending radially outward from the force receiving portion toward the proximal end, and a distal apex portion disposed on the proximal end side of the distal expansion portion and curved convexly outward in the radial direction; a second expansion portion including a base-end expansion portion extending radially outward from the tip portion of the shaft portion toward the tip direction, and a base-end apex portion disposed on the tip side of the base-end expansion portion and curved convexly outward in the radial direction; a recess that is recessed radially inward and extends to connect the base end apex and the tip end apex, and defines an accepting space that can accept biological tissue when the expandable body is expanded; and the recess has a bottom portion located at the innermost side in the radial direction, a tip-side upright portion extending radially outward from a tip of the bottom portion to the tip-side apex, and a base-side upright portion extending radially outward from a base end of the bottom portion to the base-side apex, either the distal side standing portion or the proximal side standing portion has a plurality of energy transfer element arrangement portions in which the plurality of energy transfer elements are arranged at approximately equal intervals in the circumferential direction of the expandable body, the other of the distal upright portion and the proximal upright portion has a plurality of opposing portions that face the plurality of energy transmission elements, respectively, when the expandable body is expanded; the traction shaft is configured to apply a compressive force to the expansion body via the force-receiving portion, the compressive force being a compressive force along an axial center of the shaft portion so that the plurality of energy transmission element arrangement portions and the plurality of opposing portions approach each other, by sliding relative to the shaft portion in a proximal direction; the expansion body has a buffer section disposed in the first expansion section and configured to relieve the compressive force by deforming along the distal expansion section in a direction different from the direction from the force receiving section toward the distal apex, or a buffer section disposed in the second expansion section and configured to relieve the compressive force by deforming along the proximal expansion section in a direction different from the direction from the base end of the expansion body toward the proximal apex, the energy transfer element arrangement portion is provided on the proximal upright portion, A medical device in which the buffer portion is provided only in the distal extension portion.

2. the first extension portion has a plurality of distal strut structures extending radially outward from the force receiving portion toward the proximal end and forming the distal extension portion; The medical device of claim 1, wherein each of the plurality of distal strut structures has a curved portion as the buffer portion that can be bent in a direction different from the direction from the force-receiving portion toward the distal apex along each distal strut structure.

3. Each of the plurality of distal strut structures has a first section including a first strut extending from the force-receiving portion substantially parallel to the axis of the expandable body when viewed from the outside in the radial direction, and a second section including two second struts bifurcated from a base end of the first section substantially along the circumferential direction of the expandable body, and connected to the distal apex, The medical device of claim 2 , wherein the second section functions as the buffer portion that relieves the compressive force by curving so as to increase the branching angle between the two branching second struts.

4. The medical device of claim 3, wherein the second section has a plurality of joining portions near the distal apex where each of the two second struts joins with one of the two second struts of another circumferentially adjacent second section.

5. 5. The medical device according to claim 4, wherein the second section has an auxiliary curved portion that functions as the buffer portion between the distal end apex and the plurality of confluence portions that are arranged in the same phase as the energy transmission element arrangement portion or the opposing portion in the circumferential direction of the expansion body.

6. the plurality of distal strut structures having twice the number of first sections and junctions as the plurality of energy transfer elements; 5. The medical device according to claim 4, wherein the confluence portions alternate in the circumferential direction of the expandable body with first confluence portions arranged in the same phase as the plurality of energy transfer element arrangement portions and the plurality of opposing portions, and second confluence portions arranged in a different phase from the plurality of energy transfer element arrangement portions and the plurality of opposing portions.

7. The medical device according to claim 6 , further comprising an auxiliary curved portion between the first confluence portion and the distal apex portion, the auxiliary curved portion functioning as the buffer portion.

8. the recess has a concave strut structure that is connected to the distal strut structure via the distal apex and defines the distal upstanding portion, the proximal upstanding portion, and the bottom; the concave strut structure has a plurality of bottom connecting portions at the bottom portion, the bottom connecting portions connecting each pair of the plurality of energy transfer element arrangement portions to the plurality of opposing portions; The medical device according to any one of claims 3 to 7, wherein the plurality of bottom connectors are arranged at a different phase from the first strut in the circumferential direction of the expansion body.

9. the second extension portion includes a plurality of proximal strut structures extending radially outward in a distal direction from the distal end of the shaft portion to form the proximal extension portion; 2. The medical device of claim 1, wherein each of the plurality of base-side strut structures has a third strut arranged in the same phase as the plurality of energy transfer element arrangement sections in the circumferential direction of the expandable body, and extending from the tip end of the shaft portion to the base-side apex portion approximately parallel to the axis of the expandable body when viewed from the outside in the radial direction.

10. the second expansion portion has a plurality of secondary struts that connect the third struts that are adjacent in the circumferential direction among the plurality of base-end strut structures, each of the plurality of secondary struts includes at least one support strut having two joint portions joined to two circumferentially adjacent third struts among the plurality of third struts; The medical device of claim 9 , wherein each of the plurality of support struts is formed to be longer than the linear distance between two of the joints.

11. the second extension portion includes a plurality of proximal strut structures extending radially outward in a distal direction from the distal end of the shaft portion to form the proximal extension portion; each of the plurality of base-end strut structures includes a third section including a third strut extending from the tip end of the shaft portion substantially parallel to the axis of the expandable body when viewed from the outside in the radial direction; and a fourth section including two fourth struts bifurcated from the tip end of the third section substantially along the circumferential direction of the expandable body, the fourth section being connected to the base-end apex; The medical device of claim 1 , wherein the fourth section functions as the buffer portion that relieves the compressive force by curving so that the branching angle between the two branching fourth struts increases.

12. The medical device of claim 11, wherein the fourth section has a plurality of third joining portions near the base end apex, where each of the two fourth struts joins one of the two fourth struts of another circumferentially adjacent fourth section.

13. An expandable body having a tip end including a force receiving portion and capable of expanding and contracting in a radial direction; a long shaft portion having a distal end portion to which the proximal end of the expansion body is fixed; a plurality of energy transfer elements disposed along the extension body; a traction shaft disposed inside the shaft portion, protruding from the tip end of the shaft portion, connectable to the force receiving portion of the expansion body, and slidable relative to the shaft portion; Equipped with The expansion body is a first expansion portion including a distal expansion portion extending radially outward from the force receiving portion toward the proximal end, and a distal apex portion disposed on the proximal end side of the distal expansion portion and curved convexly outward in the radial direction; a second expansion portion including a base-end expansion portion extending radially outward from the tip portion of the shaft portion toward the tip direction, and a base-end apex portion disposed on the tip side of the base-end expansion portion and curved convexly outward in the radial direction; a recess that is recessed radially inward and extends to connect the base end apex and the tip end apex, and defines an accepting space that can accept biological tissue when the expandable body is expanded; and the recess has a bottom portion located at the innermost side in the radial direction, a tip-side upright portion extending radially outward from a tip of the bottom portion to the tip-side apex, and a base-side upright portion extending radially outward from a base end of the bottom portion to the base-side apex, the proximal-side standing portion is arranged at substantially equal intervals in the circumferential direction of the expandable body, and includes a plurality of energy transfer element arrangement portions on which the plurality of energy transfer elements are arranged, respectively; the distal end side standing portion has a plurality of opposing portions that face the plurality of energy transmission elements, respectively, when the expandable body is expanded; the traction shaft is configured to apply a compressive force to the expansion body via the force-receiving portion, the compressive force being a compressive force along an axial center of the shaft portion so that the plurality of energy transmission element arrangement portions and the plurality of opposing portions approach each other, by sliding relative to the shaft portion in a proximal direction; the expansion body has a buffer portion disposed in the first expansion portion and configured to relieve the compressive force by deforming in a direction different from a direction from the force receiving portion toward the tip-side apex along the tip-side expansion portion, A medical device, wherein each of the plurality of energy transmission element arrangements extends from the base end of the bottom portion to the base end apex portion approximately parallel to the axis of the expandable body when viewed from the radial outside.

14. The recess has a plurality of bottom connecting portions at the bottom, which connect each pair of the plurality of energy transfer element arrangement portions and the plurality of opposing portions, Each of the plurality of opposing portions has a plurality of tip-side standing struts that branch into two while widening toward the tip, and a plurality of back support portions that are arranged side by side from a side closer to the bottom portion to a side closer to the tip-side top portion, The medical device described in claim 13, wherein each of the multiple back support portions connects two of the distal standing struts branching off from each of the multiple bottom connection portions, and the portion between the two ends connected to the two distal standing struts is curved so as to protrude toward the distal apex.

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