Patent Description:
Chronic heart failure is a known heart disease. Chronic heart failure is broadly classified into a systolic heart failure and a diastolic heart failure, based on a cardiac function index. In a patient suffering from the diastolic heart failure, myocardial hypertrophy appears, and stiffness (hardness) increases, so that blood pressure increases in a left atrium, and a cardiac pumping function is degraded. In this manner, the patient may show heart failure symptoms such as a pulmonary edema. In addition, there is another heart disease of a patient who shows the heart failure symptom because blood pressure increases on a right atrium side due to pulmonary hypertension, and the cardiac pumping function is degraded.

In recent years, shunt treatments have attracted attention in which, for the patients who suffer from heart failure, a shunt (through-hole) serving as an escape route for increased atrial pressure is formed in an atrial septum, thereby enabling heart failure symptoms to be alleviated. In the shunt treatment, the atrial septum is accessed using an intravenous approaching method, and the through-hole is formed to have a desired size. For example, a medical device disclosed in PTL <NUM> is used as one of medical devices for performing the shunt treatment on the atrial septum.

In the medical device of PTL <NUM>, a shunt hole is enlarged using a balloon serving as an expansion body that is provided in a distal portion of a shaft portion, and the shunt hole is maintained by an electrode provided in the balloon. However, in this medical device, the electrode (energy transfer element) is exposed to blood, so that energy is provided into the blood and an unintended site, which may cause variations in the degree of cauterization, formation of a thrombus, generation of tissue damage and the like.

This disclosure is made in order to solve the above-described problem, and an object thereof is to provide a medical device that can reduce variations in the degree of cauterization by an energy transfer element, and can suppress generation of thrombus formation, tissue damage, and the like due to the cauterization.

In order to solve the above problem the present invention provides a medical device according to claim <NUM>. The dependent claims relate to advantageous embodiments.

With the medical device configured as the above, the receiving surface is approximately parallel to the energy transfer element in accordance with the movement of the energy transfer element, so that the energy transfer element can come into close contact with the biological tissue that is clamped between the energy transfer element and the receiving surface. Therefore, variations in the degree of cauterization by the energy transfer element can be reduced. Moreover, the energy transfer element can be prevented from locally floating from the biological tissue. Therefore, the energy transfer element is prevented from supplying energy into blood and an unintended site, and generation of thrombus formation, tissue damage, and the like due to the cauterization can be suppressed.

The at least one clamping portion may include two outer peripheral portions on both sides in a width direction that is a direction orthogonal to an axis direction of the expansion body, and a direction orthogonal to the radial direction of the expansion body, relative to the back support portion. In this manner, the outer peripheral portions effectively guide the energy transfer element that moves toward the back support portion, to the back support portion that is positioned between the outer peripheral portions. Therefore, the energy transfer element can press the biological tissue supported by the two outer peripheral portions, and can press the biological tissue against the back support portion that is disposed between the two outer peripheral portions. Therefore, the energy transfer element comes into close contact with the biological tissue and is hard to float from the biological tissue, and the position of the energy transfer element relative to the biological tissue is stably maintained by the two outer peripheral portions.

The two outer peripheral portions each may have a convex shape to an outer side in the width direction. In this manner, between the two outer peripheral portions, a wide region in which the back support portion is disposed can be secured. Moreover, the two outer peripheral portions in the width direction can support the biological tissue in the wide range, so that the energy transfer element and the receiving surface that clamp the biological tissue therebetween between the two outer peripheral portions are easily maintained in the suitable positions.

The two outer peripheral portions each may have a circular arc shape that smoothly projects to the outer side in the width direction. In this manner, the outer peripheral portions is configured to be stored in an inner surface of a storage sheath without being caught thereon, which is a tubular member that stores the expansion body so as to be releasable, for example. Accordingly, the outer peripheral portions can be smoothly stored in the storage sheath, and can be smoothly released from the storage sheath.

Moreover, a maximum width of the outer peripheral portions that sandwich the back support portion therebetween in the width direction may be larger than a maximum width of the energy transfer element in the width direction. In this manner, the outer peripheral portion easily guides a press direction of the energy transfer element toward the back support portion.

The back support portion may move larger than the two outer peripheral portions due to a force in the axis direction to be received from the energy transfer element. In this manner, the back support portion can flexibly receive the biological tissue that is pressed by the energy transfer element while moving rearward larger in the press direction of the energy transfer element than the outer peripheral portion. Therefore, the energy transfer element comes into close contact with the biological tissue and is hard to float from the biological tissue.

The expansion body may include an inner projection portion between the energy transfer element and the back support portion, and the maximum width between the two outer peripheral portions that sandwich the back support portion therebetween in the width direction may be larger than a maximum width of the inner projection portion in the width direction. In this manner, while maintaining the flexibility of the inner projection portion, a structure in which the width between the two outer peripheral portions is widened can be obtained.

The back support portion may have a cantilever beam shape that extends from the wire portion. In this manner, the back support portion can warp flexibly by receiving a force.

The back support portion may be a member that is supported by at least one flexible support wire that extends from the two outer peripheral portions that sandwich the back support portion therebetween. In this manner, the back support portion can move lager than the outer peripheral portions due to a force in the axis direction.

The back support portion may be at least one flexible back support wire that extends from the two outer peripheral portions that sandwich the back support portion therebetween. In this manner, the back support portion can warp more flexibly than the outer peripheral portions due to a force in the axis direction.

The back support portion may be a mesh-like member that extends from the two outer peripheral portions that sandwich the back support portion therebetween. In this manner, the back support portion can warp more flexibly than the outer peripheral portions due to a force in the axis direction.

The back support portion may be a film body that extends from the two outer peripheral portions that sandwich the back support portion therebetween. In this manner, the back support portion can warp more flexibly than the outer peripheral portions due to a force in the axis direction.

Hereinafter, embodiments of this disclosure will be described with reference to the drawings. Note that, the size ratios in the drawings may be exaggerated for convenience of explanation, and may be different from the actual ratios in some cases. Moreover, in the present specification, a side of a medical device <NUM> to be inserted into a lumen of a living body is referred to as a "distal side", and a side at which the medical device <NUM> is operated is referred to as a "proximal side".

The medical device <NUM> according to an illustrative example not falling under the scope of the claims is configured, as shown in <FIG>, such that a through-hole Hh formed in an atrial septum HA of a heart H of a patient is enlarged, and further, a maintenance treatment that maintains the through-hole Hh having enlarged to have the increased size can be performed.

As shown in <FIG>, the medical device <NUM> according to an illustrative example not falling under the scope of the claims includes an elongated shaft portion <NUM>, an expansion body <NUM> that is provided in a distal portion of the shaft portion <NUM>, and an operation unit <NUM> that is provided in a proximal portion of the shaft portion <NUM>. In the expansion body <NUM>, an energy transfer element <NUM> for performing the aforementioned maintenance treatment is provided.

The shaft portion <NUM> includes an outer shaft <NUM> that holds the expansion body <NUM> in a distal portion thereof, and a storage sheath <NUM> that stores the outer shaft <NUM>. The storage sheath <NUM> is movable forward and rearward in an axis direction relative to the outer shaft <NUM>. The storage sheath <NUM> in a state of having moved to a distal side of the shaft portion <NUM> can store the expansion body <NUM> in an inside thereof. The storage sheath <NUM> is moved to a proximal side in a state where the expansion body <NUM> is stored to enable the expansion body <NUM> to be exposed.

A pulling shaft <NUM> is stored in an inside of the outer shaft <NUM>. The pulling shaft <NUM> protrudes from a distal end of the outer shaft <NUM> to the distal side, and has a distal portion that is fixed to a distal member <NUM>. A proximal portion of the pulling shaft <NUM> is drawn out to the proximal side of the operation unit <NUM>. The distal member <NUM> to which the distal portion of the pulling shaft <NUM> is fixed does not need to be fixed to the expansion body <NUM>. In this manner, the distal member <NUM> can pull the expansion body <NUM> in a contracting direction. Moreover, when the expansion body <NUM> is stored in the storage sheath <NUM>, the distal member <NUM> is separated from the expansion body <NUM> to the distal side, so that movement of the expansion body <NUM> in an extending direction becomes easy to enable the storage capability to be improved.

The operation unit <NUM> includes a housing <NUM> to be gripped by an operator, an operation dial <NUM> that can be rotationally operated by the operator, and a conversion mechanism <NUM> that is operated in conjunction with the rotation of the operation dial <NUM>. The pulling shaft <NUM> is held by the conversion mechanism <NUM> in the inside of the operation unit <NUM>. The conversion mechanism <NUM> can move the pulling shaft <NUM> that is held by the conversion mechanism <NUM> forward and rearward along the axis direction in conjunction with the rotation of the operation dial <NUM>. As the conversion mechanism <NUM>, for example, a rack and pinion mechanism can be used.

The expansion body <NUM> will be described in more details. As shown in <FIG> and <FIG>, the expansion body <NUM> includes a plurality of wire portions <NUM> in a circumferential direction. In the present illustrative example not falling under the scope of the claims , the four wire portions <NUM> are provided in the circumferential direction. Note that, the number of the wire portions <NUM> is not specially limited. The wire portions <NUM> can respectively expand and contract in a radial direction of the expansion body <NUM>. In a natural state where no external force acts, the expansion body <NUM> becomes in a reference form in which the expansion body <NUM> is developed in the radial direction. A proximal portion of the wire portion <NUM> extends from a distal portion of the outer shaft <NUM> to the distal side. A distal portion of the wire portion <NUM> extends from a proximal portion of the distal member <NUM> to the proximal side. The wire portion <NUM> is inclined to increase in the radial direction from both end portions to a central portion in an axis direction of the expansion body <NUM>. Moreover, the wire portion <NUM> includes a clamping portion <NUM> having a valley shape in an axial central portion, in the radial direction of the expansion body <NUM>.

The clamping portion <NUM> includes a proximal side clamping portion <NUM> and a distal side clamping portion <NUM>. The clamping portion <NUM> further includes a proximal side outer projection portion <NUM>, an inner projection portion <NUM>, and a distal side outer projection portion <NUM>. An interval between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM> is preferably opened slightly larger in the axis direction on an outer side than on an inner side in the radial direction, in the reference form. This makes it easy to dispose a biological tissue between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM>, from the outer side in the radial direction.

The proximal side outer projection portion <NUM> is positioned on a proximal side of the proximal side clamping portion <NUM>, and is formed in a convex shape toward the outer side in the radial direction.

The inner projection portion <NUM> is positioned between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM>, and is formed in a convex shape toward the inner side in the radial direction. A central through-hole <NUM> is formed in the inner projection portion <NUM> such that the inner projection portion <NUM> easily bends.

The distal side outer projection portion <NUM> is positioned on a distal side of the distal side clamping portion <NUM>, and is formed in a convex shape to the outer side in the radial direction. In the wire portion <NUM>, one distal side through-hole <NUM> is formed in the vicinity of the distal side outer projection portion <NUM> and the distal side clamping portion <NUM>. The distal side through-hole <NUM> penetrates into the radial direction of the expansion body <NUM>. In this manner, the distal side outer projection portion <NUM> has low flexural rigidity. Therefore, the distal side outer projection portion <NUM> easily deforms to have a convex shape toward the outer side in the radial direction, and easily deforms such that the convex shape becomes flat. Note that, the number of the distal side through-holes <NUM> is not specially limited. Accordingly, the number of the distal side through-holes <NUM> may be two or more.

The proximal side clamping portion <NUM> includes a projection portion <NUM> that protrudes toward the distal side. In the projection portion <NUM>, the energy transfer element <NUM> is disposed.

The distal side clamping portion <NUM> includes two outer peripheral portions <NUM> that are provided on both outer sides in a width direction, and a back support portion <NUM> that is provided between the two outer peripheral portions <NUM>. The width direction is a direction orthogonal to the axis direction of the expansion body <NUM>, and a direction orthogonal to the radial direction of the expansion body <NUM>. The back support portion <NUM> includes a receiving surface <NUM> that can face the energy transfer element <NUM> that is disposed in the distal side clamping portion <NUM> when the expansion body <NUM> expands.

Each of the outer peripheral portions <NUM> has a circular arc shape that projects toward the outer side in the width direction. Therefore, between the two outer peripheral portions <NUM>, a wide region in which the back support portion <NUM> and the distal side through-hole <NUM> are disposed can be secured. In addition, an outer side of the outer peripheral portion <NUM> in the width direction becomes smooth, so that the outer peripheral portion <NUM> is prevented from being caught on an inner surface of the storage sheath <NUM> that stores therein the expansion body <NUM>. A maximum width L1 between the outer peripheral portions <NUM> in the width direction is larger than a maximum width L2 of the inner projection portion <NUM> in the width direction. Therefore, while maintaining the easiness of bending of the inner projection portion <NUM>, the outer peripheral portions <NUM> can be formed in a shape expanding in the width direction. Moreover, a maximum width L5 of the receiving surface <NUM> in the width direction is not specially limited, but is preferably the same as or slightly larger than a maximum width L3 of the energy transfer element <NUM> in the width direction. In this manner, the receiving surface <NUM> can appropriately receive a biological tissue that is pressed by the energy transfer element <NUM>. Moreover, the maximum width L1 between the outer peripheral portions <NUM> in the width direction is not specially limited, but is preferably larger than the maximum width L3 of the energy transfer element <NUM> in the width direction. Moreover, a maximum width L4 of the distal side through-hole <NUM> in the width direction is not specially limited, but is preferably larger than the maximum width L3 of the energy transfer element <NUM> in the width direction.

The back support portion <NUM> protrudes between the two outer peripheral portions <NUM> from a site on a side of the inner projection portion <NUM> of the distal side clamping portion <NUM> toward a side of the distal side outer projection portion <NUM>. The back support portion <NUM> is disposed between the two outer peripheral portions <NUM> to be spaced from the two outer peripheral portions <NUM>. An end portion of the back support portion <NUM> on the side of the distal side outer projection portion <NUM> is a free end. Accordingly, the back support portion <NUM> has a cantilever beam-like form in which a proximal portion thereof is fixed, and is easy to warp. Therefore, the back support portion <NUM> can more easily warp than each of the outer peripheral portions <NUM> due to a force toward the distal side that is received by the receiving surface <NUM>. The back support portion <NUM> is disposed so as to be sandwiched by the two outer peripheral portions <NUM>, but does not necessarily need to be strictly positioned in the space positioned between the two outer peripheral portions <NUM>. The back support portion <NUM> may be disposed so as to be sandwiched by the two outer peripheral portions <NUM> at a position slightly shifted from the space positioned between the two outer peripheral portions <NUM>. Note that, at least a part of the back support portion <NUM> is preferably disposed in the space positioned between the two outer peripheral portions <NUM>.

In the back support portion <NUM>, one back support through-hole <NUM> is formed on the proximal side, in other words, on a side close to the inner projection portion <NUM>. The back support through-hole <NUM> penetrates into the radial direction of the expansion body <NUM> (the thickness direction of the wire portions <NUM>). In this manner, the back support portion <NUM> has low flexural rigidity on a side close to the inner projection portion <NUM>. Therefore, the back support portion <NUM> can easily warp due to a force that is received by the receiving surface <NUM>. Note that, the number of the back support through-holes <NUM> is not specially limited. Accordingly, the number of the back support through-holes <NUM> may be two or more. Moreover, no back support through-hole <NUM> may be formed in the back support portion <NUM>.

In the present illustrative example not falling under the scope of the claims, the energy transfer element <NUM> is provided in the proximal side clamping portion <NUM> and the back support portion <NUM> is provided in the distal side clamping portion <NUM>, and alternatively, the energy transfer element <NUM> may be provided in the distal side clamping portion <NUM> and the back support portion <NUM> may be provided in the proximal side clamping portion <NUM>.

The wire portion <NUM> forming the expansion body <NUM> has a flat plate shape cut from a cylinder, for example. The wire forming the expansion body <NUM> can have a thickness of <NUM> to <NUM> and a width of <NUM> to <NUM>. However, the wire forming the expansion body <NUM> has a size outside this range. Moreover, the shape of the wire portion <NUM> is not limited, and may have a circular shape in a cross section or other shapes in a cross section, for example.

The energy transfer element <NUM> is provided in the projection portion <NUM> of the proximal side clamping portion <NUM>, so that when the clamping portion <NUM> clamps the atrial septum HA, the energy from the energy transfer element <NUM> is transferred to the atrial septum HA from the right atrium side. Note that, in a case where the energy transfer element <NUM> is provided in the distal side clamping portion <NUM>, the energy from the energy transfer element <NUM> is transferred to the atrial septum HA from the left atrium side.

The energy transfer element <NUM> is configured to include, for example, a bipolar electrode that receives electric energy from an energy supply device (not illustrated) serving as an external device. In this case, electricity is supplied among the energy transfer elements <NUM> disposed in the respective wire portions <NUM>. The energy transfer element <NUM> and the energy supply device are connected to each other by a conductive wire (not illustrated) coated with an insulating coating material. The conductive wire is drawn out to the outside via the shaft portion <NUM> and the operation unit <NUM>, and is connected to the energy supply device.

Alternatively, the energy transfer element <NUM> may be configured as a monopolar electrode. In this case, the electricity is supplied between the energy transfer element <NUM> and a counter electrode plate prepared outside the body. Moreover, the energy transfer element <NUM> may be a heating element (electrode chip) that generates heat by receiving high-frequency electric energy from the energy supply device. In this case, electricity is supplied among the energy transfer elements <NUM> disposed in the respective wire portions <NUM>. In addition, the energy transfer element <NUM> can be configured to include an element that can apply energy to the through-hole Hh, such as an element that provides heating or cooling operation by using microwave energy, ultrasound energy, coherent light such as laser, a heated fluid, a cooled fluid, or a chemical medium, an element that generates frictional heat, or a heater including an electric wire, and a specific form of the energy transfer element <NUM> is not specially limited.

The wire portion <NUM> can be formed of a metal material. As the metal material, for example, a titanium-based (Ti-Ni, Ti-Pd, Ti-Nb-Sn, or the like) alloy, a copper-based alloy, stainless steel, β titanium steel, or a Co-Cr alloy can be used. Note that, an alloy having a spring property such as a nickel titanium alloy may be more preferably used. However, a material for the wire portion <NUM> is not limited to these, and the wire portion <NUM> may be formed of other materials.

The shaft portion <NUM> includes an inner shaft <NUM> in the inside of the outer shaft <NUM>, and the pulling shaft <NUM> is stored in an inside of the inner shaft <NUM>. A guide wire lumen is formed in the pulling shaft <NUM> and the distal member <NUM> along the axis direction, and a guide wire <NUM> can be inserted through the guide wire lumen.

The storage sheath <NUM>, the outer shaft <NUM>, the inner shaft <NUM> of the shaft portion <NUM> are preferably formed of a material having a certain degree of flexibility. Examples of such the material can include polyolefin such as polyethylene, polypropylene, polybutene, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer, an ionomer, or a mixture of two or more of them, soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, fluorine resin such as polytetrafluoroethylene, polyimide, PEEK, silicone rubber, and latex rubber.

The pulling shaft <NUM> can be formed of, for example, an elongated wire material including a super elasticity alloy such as a nickel-titanium alloy and a copper-zinc alloy, a metal material such as stainless steel, and a resin material having comparatively high rigidity. Moreover, the pulling shaft <NUM> may be formed of the abovementioned wire material coated with a resin material such as polyvinyl chloride, polyethylene, polypropylene, an ethylene-propylene copolymer, or fluorine resin.

The distal member <NUM> can be formed of, for example, a super elasticity alloy such as a nickel-titanium alloy and a copper-zinc alloy, a metal material such as stainless steel, and a resin material having comparatively high rigidity.

Next, a treatment method using the medical device <NUM> according to the present illustrative example not falling under the scope of the claims will be described. The treatment method is performed on a patient suffering from a heart failure (left heart failure). More specifically, as shown in <FIG>, the treatment method is performed on the patient suffering from a chronic heart failure, who has a high blood pressure in a left atrium HLa due to myocardial hypertrophy appearing in a left ventricle of the heart H and increased stiffness (hardness).

When the through-hole Hh is formed, an operator delivers an introducer in which a guiding sheath and a dilator are combined with each other to the vicinity of the atrial septum HA. The introducer can be delivered to a right atrium HRa via an inferior vena cava Iv, for example. Moreover, the introducer can be delivered using the guide wire <NUM>. The operator can insert the guide wire <NUM> into the dilator, and can deliver the introducer along the guide wire <NUM>. Note that, the insertion of the introducer, the insertion of the guide wire <NUM>, and the like to a living body can be performed by using a publicly known method such as using an introducer for blood vessel introduction.

Next, the operator causes a puncture device (not illustrated) and the dilator to penetrate from the right atrium HRa side toward the left atrium HLa side, thereby forming the through-hole Hh. As the puncture device, for example, a device such as a wire having a sharp distal end can be used. The puncture device is inserted into the dilator, and is delivered to the atrial septum HA. The puncture device can be delivered to the atrial septum HA instead of the guide wire <NUM> after the guide wire <NUM> is extracted from the dilator.

Next, as shown in <FIG>, the operator delivers the medical device <NUM> to the vicinity of the atrial septum HA along the guide wire <NUM> inserted in advance into the left atrium HLa from the right atrium HRa via the through-hole Hh. Further, as shown in <FIG>, a part of a distal portion of the medical device <NUM> passes through the through-hole Hh opened in the atrial septum HA, and reaches the left atrium HLa. When the medical device <NUM> is inserted, the expansion body <NUM> is in a contracted form in which the expansion body <NUM> is stored in the storage sheath <NUM>. In the contracted form, the proximal side outer projection portion <NUM>, the inner projection portion <NUM>, and the distal side outer projection portion <NUM> having convex shapes in a natural state deforms into a shape close to a flat shape, so that the expansion body <NUM> contracts in the radial direction.

Next, as shown in <FIG>, the storage sheath <NUM> is moved to the proximal side, thereby exposing a portion on a distal side of the expansion body <NUM> in the left atrium HLa. In this manner, the portion on the distal side in the expansion body <NUM> is developed in the radial direction in the left atrium HLa due to a self-restoring force. Next, as shown in <FIG>, the storage sheath <NUM> is moved to the proximal side, thereby exposing the entire expansion body <NUM>. In this manner, the portion on the proximal side in the expansion body <NUM> is developed in the radial direction in the right atrium HRa due to a self-restoring force. In this process, the inner projection portion <NUM> is disposed to an inner side of the through-hole Hh. In this manner, the entire expansion body <NUM> is developed due to the self-restoring force, and is recovered to an original reference form or a form close to the reference form. In this case, the atrial septum HA is disposed between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM>. In a clamping direction of the biological tissue, the atrial septum HA is disposed between the energy transfer element <NUM> and the back support portion <NUM>. Note that, the expansion body <NUM> is brought into contact with the through-hole Hh, and thus is not completely returned to the reference form but may be returned to a shape close to the reference form. Note that, in this state, the expansion body <NUM> is not covered with the storage sheath <NUM>, and does not receive a force from the pulling shaft <NUM>. This form of the expansion body <NUM> can be defined as being included in the reference form.

Each of the outer peripheral portions <NUM> has a circular arc shape that projects to the outer side in the width direction. Therefore, the outer peripheral portion <NUM> is hard to be caught on the inner surface of the storage sheath <NUM>. Accordingly, the expansion body <NUM> including the outer peripheral portions <NUM> is smoothly released from the storage sheath <NUM>.

Next, the operator operates the operation unit <NUM> in a state where the clamping portion <NUM> holds the atrial septum HA, thereby moving the pulling shaft <NUM> to the proximal side. In this manner, as shown in <FIG>, the expansion body <NUM> that receives a contracting force in the axis direction becomes in an expanded form in which the expansion body <NUM> has expanded more in the radial direction than in the reference form. The expansion body <NUM> becomes in the expanded form, so that the proximal side clamping portion <NUM> and the distal side clamping portion <NUM> come closer to each other, and the atrial septum HA is clamped between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM>. In this process, the energy transfer element <NUM> and the back support portion <NUM> face each other. The clamping portion <NUM> in the state of clamping the atrial septum HA further expands to widen the through-hole Hh in the radial direction.

As shown in <FIG>, when the proximal side clamping portion <NUM> and the distal side clamping portion <NUM> come closer to each other from the state where the proximal side clamping portion <NUM> and the distal side clamping portion <NUM> are separated from each other, as shown in <FIG>, the atrial septum HA is clamped between the proximal side clamping portion <NUM> and the distal side clamping portion <NUM>. Further, the energy transfer element <NUM> presses the atrial septum HA to the distal side. In this process, the distal side clamping portion <NUM> causes the back support portion <NUM> to warp to the distal side between the two outer peripheral portions <NUM>, and receives the atrial septum HA that is pressed by the energy transfer element <NUM>, between the two outer peripheral portions <NUM>. The receiving surface <NUM> of the back support portion <NUM> receives a force via the atrial septum HA from the energy transfer element <NUM>, and warps so as to be approximately parallel to the energy transfer element <NUM>. Further, the back support portion <NUM> causes, while flexibly warping, a repulsion force in a reverse direction of a press-in direction of the energy transfer element <NUM> to act on the atrial septum HA that is pressed by the energy transfer element <NUM>. In this manner, the energy transfer element <NUM> comes into close contact with the atrial septum HA. Moreover, the energy transfer element <NUM> can be prevented from locally floating from the atrial septum HA.

Moreover, when the energy transfer element <NUM> is brought into contact with the atrial septum HA, the two outer peripheral portions <NUM> that sandwich the back support portion <NUM> therebetween effectively guide the energy transfer element <NUM> to the back support portion <NUM> that is positioned between the outer peripheral portions <NUM>. In this manner, the energy transfer element <NUM> can press the atrial septum HA that is supported by the two outer peripheral portions <NUM> while coming into contact with the atrial septum HA, and can press the atrial septum HA against the back support portion <NUM> that is disposed between the two outer peripheral portions <NUM>. Therefore, the energy transfer element <NUM> comes into close contact with the atrial septum HA and is hard to float from the atrial septum HA, and a position of the energy transfer element <NUM> relative to the atrial septum HA is stably maintained between the two outer peripheral portions <NUM>.

The atrial septum HA is clamped between the energy transfer element <NUM> and the back support portion <NUM>, while being clamped in an uneven structure of the projection portion <NUM> and the distal side through-hole <NUM>. In this process, the back support portion <NUM> warps, so that the atrial septum HA is easily clamped in the uneven structure of the projection portion <NUM> and the distal side through-hole <NUM>. In this manner, the proximal side clamping portion <NUM> and the distal side clamping portion <NUM> support with each other in a circumferential direction of the expansion body <NUM>, so that a position shift of the expansion body <NUM> in the circumferential direction can be suppressed therebetween. Therefore, an expanding force of the expansion body <NUM> can be reliably transferred to the biological tissue. The proximal side clamping portion <NUM> and the distal side clamping portion <NUM> clamp the biological tissue when the expansion body <NUM> expands. When the expansion body <NUM> expands indicates any one of the middle of the expansion of the expansion body <NUM>, the instant when the expansion body <NUM> completely expands, and the time from when the expansion body <NUM> completely expands to when the expansion body <NUM> contracts.

Further, the maximum width L1 between the outer peripheral portions <NUM> in the width direction is larger than the maximum width L2 of the inner projection portion <NUM> in the width direction. Therefore, while flexibly maintaining the inner projection portion <NUM>, a region in which the back support portion <NUM> is disposed is easily secured between the two outer peripheral portions <NUM>. Moreover, the maximum width L1 between the outer peripheral portions <NUM> in the width direction is larger than the maximum width L3 of the energy transfer element <NUM> in the width direction. Therefore, the outer peripheral portions <NUM> easily guide the press direction of the energy transfer element <NUM> toward the back support portion <NUM>. Moreover, the maximum width L4 of the distal side through-hole <NUM> in the width direction is larger than the maximum width L3 of the energy transfer element <NUM> in the width direction. Therefore, the outer peripheral portions <NUM> easily guide the press direction of the energy transfer element <NUM> toward the back support portion <NUM>. In addition, the energy transfer element <NUM> easily enter between the outer peripheral portions <NUM>, so that a force in which the proximal side clamping portion <NUM> including the energy transfer element <NUM> and the distal side clamping portion <NUM> including the outer peripheral portions <NUM> support with each other in the circumferential direction of the expansion body <NUM> easily acts therebetween.

After the through-hole Hh has been enlarged, the hemodynamics is confirmed. As shown in <FIG>, the operator delivers a hemodynamics confirming device <NUM> to the right atrium HRa via the inferior vena cava Iv. As the hemodynamics confirming device <NUM>, for example, a publicly known echo catheter can be used. The operator can cause an echo image acquired by the hemodynamics confirming device <NUM> to be displayed on a display apparatus such as a display, and can confirm a blood volume passing through the through-hole Hh based on a displayed result.

Next, the operator performs maintenance treatment for maintaining the size of the through-hole Hh. In the maintenance treatment, energy is applied to an edge portion of the through-hole Hh through the energy transfer element <NUM>, thereby cauterizing (heating and cauterizing) the edge portion of the through-hole Hh by using the energy. When the biological tissue in the vicinity of the edge portion of the through-hole Hh is cauterized through the energy transfer element <NUM>, a degenerated portion having the degenerated biological tissue is formed in the vicinity of the edge portion. The biological tissue in the degenerated portion is in a state where elasticity is lost, so that the through-hole Hh can maintain a shape widened by the expansion body <NUM>.

The medical device <NUM> includes the back support portion <NUM>, so that the energy transfer element <NUM> comes into close contact with the atrial septum HA. Therefore, variations in the degree of cauterization by the energy transfer element <NUM> can be reduced. Moreover, the energy transfer element <NUM> can be prevented from locally floating from the atrial septum HA. Therefore, the energy transfer element <NUM> is prevented from supplying energy into blood and an unintended site, and generation of thrombus formation, tissue damage, and the like can be suppressed.

Moreover, the energy transfer element <NUM> is disposed in the projection portion <NUM> of the proximal side clamping portion <NUM>. Therefore, the projection portion <NUM> is pressed against the atrial septum HA, whereby the maintenance treatment is performed in a state where the energy transfer element <NUM> is embedded in the biological tissue. In this manner, the energy transfer element <NUM> is prevented from supplying energy into blood and an unintended site, and generation of thrombus formation, tissue damage, and the like can be suppressed.

After the maintenance treatment, the hemodynamics are confirmed again, and in a case where the volume of blood passing through the through-hole Hh reaches a desired amount, the operator decreases the diameter of the expansion body <NUM>, and stores the expansion body <NUM> in the storage sheath <NUM> and then extracts the expansion body <NUM> from the through-hole Hh. The outer peripheral portion <NUM> has a circular arc shape that projects to the outer side in the width direction, and thus is hard to be caught on the inner surface of the storage sheath <NUM>. Accordingly, the expansion body <NUM> including the outer peripheral portions <NUM> is smoothly stored in the storage sheath <NUM>. In addition, the operator extracts the entire medical device <NUM> to the outside of the living body, and ends the treatment.

As in the foregoing, the medical device <NUM> according to the abovementioned illustrative example not falling under the scope of the claims includes: the elongated shaft portion <NUM>, and the expansion body <NUM> that is provided in a distal portion of the shaft portion <NUM> and can expand and contract in a radial direction, in which: the expansion body <NUM> includes a plurality of wire portions <NUM> that are linked with the shaft portion <NUM>, and at least one clamping portion <NUM> that is formed by at least one wire portion <NUM>; the clamping portion <NUM> includes the energy transfer element <NUM> that outputs energy, and the back support portion <NUM>; the back support portion <NUM> includes the receiving surface <NUM> that can face the energy transfer element <NUM> when the expansion body <NUM> expands; and the receiving surface <NUM> can be inclined so as to be approximately parallel to the energy transfer element <NUM> when the energy transfer element <NUM> moves toward the back support portion <NUM>. In this manner, in the medical device <NUM>, the receiving surface <NUM> is approximately parallel to the energy transfer element <NUM> in accordance with the movement of the energy transfer element <NUM>, so that the energy transfer element <NUM> can come into close contact with the biological tissue between the energy transfer element <NUM> and the receiving surface <NUM>. Therefore, variations in the degree of cauterization by the energy transfer element <NUM> can be reduced. Moreover, the energy transfer element <NUM> can be prevented from locally floating from the biological tissue. Therefore, the energy transfer element <NUM> is prevented from supplying energy into blood and an unintended site, and generation of thrombus formation, tissue damage, and the like due to the cauterization can be suppressed. In the present illustrative example not falling under the scope of the claims , the back support portion <NUM> is inclined by warping due to a force in the axis direction. Note that, the back support portion <NUM> can be inclined without warping by being supported by another deformable member, as shown in a first embodiment (see <FIG>), which is described later, for example.

Moreover, at least one clamping portion <NUM> may include the two outer peripheral portions <NUM> on both sides in a width direction that is a direction orthogonal to the axis direction of the expansion body <NUM>, and a direction orthogonal to the radial direction of the expansion body <NUM>, relative to the back support portion <NUM>. In this manner, the outer peripheral portions <NUM> effectively guide the energy transfer element <NUM> that moves toward the back support portion <NUM> to the back support portion <NUM> that is positioned between the outer peripheral portions <NUM>. Therefore, the energy transfer element <NUM> can press the biological tissue supported by the two outer peripheral portions <NUM>, and press the biological tissue against the back support portion <NUM> that is disposed between the two outer peripheral portions <NUM>. Therefore, the energy transfer element <NUM> comes into close contact with the biological tissue and is hard to float from the biological tissue, and the position of the energy transfer element relative to the biological tissue is stably maintained by the two outer peripheral portions <NUM>.

Moreover, the two outer peripheral portions <NUM> each have a convex shape to the outer side in the width direction. In this manner, between the two outer peripheral portions <NUM>, a wide region in which the back support portion <NUM> is disposed can be secured. Moreover, the two outer peripheral portions <NUM> in the width direction can support the biological tissue in the wide range, so that the energy transfer element <NUM> and the receiving surface <NUM> that clamp the biological tissue between the two outer peripheral portions <NUM> are easily maintained in the suitable positions.

Moreover, the two outer peripheral portions <NUM> each have a circular arc shape that smoothly projects to the outer side in the width direction. In this manner, the outer peripheral portion <NUM> can be stored without being caught on the inner surface of, for example, the storage sheath <NUM> for storing the expansion body <NUM> so as to be releasable. Accordingly, the outer peripheral portions <NUM> can be smoothly stored in the storage sheath <NUM>, and can be smoothly released from the storage sheath <NUM>.

Moreover, the maximum width L1 between the outer peripheral portions <NUM> that sandwich the back support portion <NUM> therebetween in the width direction is larger than the maximum width L3 of the energy transfer element <NUM> in the width direction. In this manner, the outer peripheral portions <NUM> easily guide the press direction of the energy transfer element <NUM> toward the back support portion <NUM>.

Moreover, the back support portion <NUM> moves more than the two outer peripheral portions <NUM> due to a force in the axis direction to be received from the energy transfer element <NUM>. In this manner, the back support portion <NUM> can flexibly receive the biological tissue that is pressed by the energy transfer element <NUM> while retracting more than the outer edge portion <NUM> in the pressing direction of the energy transfer element <NUM>. Therefore, the energy transfer element <NUM> comes into close contact with the biological tissue, and is hard to float from the biological tissue.

Moreover, the expansion body <NUM> includes the inner projection portion <NUM> that projects to the inner side in the radial direction, between the energy transfer element <NUM> and the back support portion <NUM>, and the maximum width L1 between the outer peripheral portions <NUM> that sandwich the back support portion <NUM> therebetween in the width direction is larger than the maximum width L2 of the inner projection portion <NUM> in the width direction. In this manner, while maintaining the flexibility of the inner projection portion <NUM>, a structure in which the width between the two outer peripheral portions <NUM> is widened can be obtained. The inner projection portion <NUM> is flexible to enable the expansion body <NUM> to be stored in the storage sheath <NUM>, for example. Moreover, the inner projection portion <NUM> is flexible to make it easy to bring the energy transfer element <NUM> and the back support portion <NUM> that sandwich the inner projection portion <NUM> therebetween close to or separate from each other.

Moreover, the back support portion <NUM> have a cantilever beam shape that extends from the wire portion <NUM>. In this manner, the back support portion <NUM> can warp flexibly by receiving a force.

Moreover, this disclosure further provides a treatment method. The treatment method is a cauterization method of cauterizing a biological tissue, in which: a cauterization device is inserted into a right atrium, the cauterization device including the elongated shaft portion <NUM>, and the expansion body <NUM> that is provided in a distal portion of the shaft portion <NUM> and can expand and contract in a radial direction, in which the expansion body <NUM> includes a plurality of wire portions <NUM> that are linked with the shaft portion <NUM>, and at least one clamping portion <NUM> that is formed by at least one wire portion <NUM>, the clamping portion <NUM> includes the energy transfer element <NUM> that outputs energy, and the back support portion <NUM>, and the back support portion <NUM> includes the receiving surface <NUM> that can face the energy transfer element <NUM> when the expansion body <NUM> expands; a distal portion of the expansion body <NUM> contracted in the radial direction is inserted into the left atrium via the through-hole Hh opened in the atrial septum HA; the distal portion of the contracted expansion body <NUM> is developed in the left atrium due to a self-restoring force, and a proximal portion of the contracted expansion body <NUM> is developed in the right atrium HRa due to a self-restoring force, whereby a biological tissue in the vicinity of the edge portion of the through-hole Hh in the atrial septum HA is disposed between the energy transfer element <NUM> and the back support portion <NUM>; the developed expansion body <NUM> is expanded in the radial direction, whereby the through-hole Hh is widened while clamping the biological tissue by the clamping portion <NUM>; with the expansion of the through-hole Hh, the biological tissue is pressed toward the back support portion <NUM> by the energy transfer element <NUM>; the receiving surface <NUM> of the back support portion <NUM> is caused to warp so as to be approximately parallel to the energy transfer element <NUM>; a repulsion force from the receiving surface <NUM> of the back support portion <NUM> is caused to act on the biological tissue, whereby the energy transfer element <NUM> is brought into close contact with the biological tissue; and the biological tissue is cauterized by the energy to be output from the energy transfer element <NUM> having brought into close contact with the biological tissue.

In the cauterization method configured as the above, in accordance with the movement of the energy transfer element <NUM>, the receiving surface <NUM> becomes approximately parallel to the energy transfer element <NUM>, so that the energy transfer element <NUM> can be brought into close contact with the biological tissue between the energy transfer element <NUM> and the receiving surface <NUM>. Therefore, variations in the degree of cauterization by the energy transfer element <NUM> can be reduced. Moreover, the energy transfer element <NUM> can be prevented from locally floating from the biological tissue. Therefore, the energy transfer element <NUM> is prevented from supplying energy into blood and an unintended site, and generation of thrombus formation, tissue damage, and the like due to the cauterization can be suppressed.

Various changes by those skilled in the art can be made within the technical scope of the present invention as defined by the claims. For example, as a first modification example shown in <FIG>, the outer peripheral portion <NUM> does not need to be formed in a convex shape to the outer side in the width direction.

Moreover, the form of the back support portion <NUM> is not limited. For example, as the first embodiment shown in <FIG>, the back support portion <NUM> does not need to have a cantilever beam-like form, but may be supported by at least one, preferably a plurality of flexible support wires <NUM> that extend from the two outer peripheral portions <NUM>. The support wire <NUM> is thinner and more flexible than the outer peripheral portion <NUM>. A constituent material for the support wire <NUM> is not specially limited as long as it can flexibly deform, and for example, a super elasticity alloy such as a nickel-titanium alloy and a copper-zinc alloy, a metal material such as stainless steel, polyolefin such as polyethylene, polypropylene, polybutene, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer, an ionomer, or a mixture of two or more of them, soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, fluorine resin such as polytetrafluoroethylene, and a resin material such as polyimide, PEEK, silicone rubber, or latex rubber can be preferably used. The back support portion <NUM> is linked with the outer peripheral portions <NUM> only by the support wires <NUM>. Therefore, the back support portion <NUM> can be inclined easier by receiving a force in the axis direction, than the outer peripheral portion <NUM>. A plurality of the support wires <NUM> may be provided and disposed approximately in parallel to each other. Moreover, a plurality of the support wires <NUM> may be provided and disposed in a mesh shape.

Moreover, as a second embodiment shown in <FIG>, the back support portion <NUM> may include at least one, preferably a plurality of back support wires <NUM> having both ends that are fixed to the outer peripheral portions <NUM>. A constituent material for the back support wire <NUM> is not specially limited as long as it can flexibly deform, and for example, the above-mentioned material applicable to the support wire <NUM> can be used suitably. The receiving surface <NUM> of the back support portion <NUM> is formed by the plurality of the back support wires <NUM> with gaps.

Moreover, as another illustrative example not falling under the scope of the claims and shown in <FIG>, the back support portion <NUM> may be a mesh-like member that is disposed between the two outer peripheral portions <NUM>. The mesh-like member may include, for example, a plurality of fine lines, or a flexible member having a large number of holes being formed therein. A constituent material for the mesh-like member is not specially limited as long as it can flexibly deform, and for example, the above-mentioned material applicable to the support wire <NUM> can be used suitably.

Claim 1:
A medical device (<NUM>) comprising:
an elongated shaft portion (<NUM>, <NUM>); and
an expansion body (<NUM>) that is provided in a distal portion of the shaft portion (<NUM>, <NUM>), and is configured to expand and contract in a radial direction, wherein
the expansion body (<NUM>) includes a plurality of wire portions (<NUM>) that are linked with the shaft portion (<NUM>, <NUM>), and at least one clamping portion (<NUM>) that is formed by at least one of the wire portions (<NUM>),
the clamping portion (<NUM>) includes an energy transfer element (<NUM>) that outputs energy, and a back support portion (<NUM>),
the back support portion (<NUM>) includes a receiving surface (<NUM>) that is configured to face the energy transfer element (<NUM>) when the expansion body (<NUM>) expands, and
the receiving surface (<NUM>) is configured to be inclined so as to be approximately parallel to the energy transfer element (<NUM>), when the energy transfer element (<NUM>) moves toward the back support portion (<NUM>),
wherein at least one clamping portion (<NUM>) includes two outer peripheral portions (<NUM>) on both sides in a width direction that is a direction orthogonal to an axis direction of the expansion body (<NUM>), and a direction orthogonal to the radial direction of the expansion body (<NUM>), relative to the back support portion (<NUM>), and
characterized in that
the back support portion (<NUM>) is a member that is supported by at least one flexible support wire (<NUM>) that extends from the two outer peripheral portions (<NUM>) that sandwich the back support portion (<NUM>) therebetween, or is at least one flexible back support wire (<NUM>) that extends from the two outer peripheral portions (<NUM>) that sandwich the back support portion (<NUM>) therebetween.