Patent Description:
Chronic heart failure is one of known heart diseases. The 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, a myocardium is hypertrophied and increases in stiffness (hardness), so that the blood pressure in a left atrium increases and the pumping function of a heart is decreased. Accordingly, the patient shows a heart failure symptom such as a pulmonary edema. There is also a heart disease in which the blood pressure on a right atrium side increases due to pulmonary hypertension or the like, and the pump function of a heart is decreased, thereby showing heart failure symptoms.

In recent years, for the patients suffering from a heart failure, attention has been paid to a shunt treatment in which a shunt (through-hole) serving as an escape route for increased atrial pressure is formed in an atrial septum, thereby being able to reduce heart failure symptoms. In the shunt treatment, the atrial septum is accessed using a transvenous approach method, and a through-hole is formed. Then, a method has been known in which a through-hole is widened to a desired size and the through-hole is subjected to energy and cauterized, to form a shunt hole.

In addition, a method for widening a formed hole in a biological lumen is performed in cases other than the case of forming a shunt hole in the atrial septum. For example, PTL <NUM> discloses a device that cuts and widens a blood vessel that is narrowed by arterioscleosis. In the device, an outer shaft is fixed to proximal portions of a plurality of expandable portions extending in an axial direction at a distal portion of the device, and an inner shaft penetrating through the outer shaft is fixed to distal portions of the plurality of expandable portions. Therefore, when the inner shaft is pulled to a proximal side with respect to the outer shaft, a compression force acts on the expandable portions, and the expandable portions are expanded to bend outward in a radial direction.

In the device disclosed in PTL <NUM>, when the inner shaft is pulled to expand the expandable portions, the inner shaft may be bent, and a central axis of the expandable portions and a pulling axis of the inner shaft may be displaced from each other. In this case, the plurality of expandable portions arranged in a circumferential direction are not uniform, and an expansion force of the expandable portions is not uniform. Accordingly, the expansion force may be decreased, or a hole in a living body may be not expandable to a desired shape.

On the other hand, when a tube side shaft to be pulled so as to expand the expandable portions is made rigid, since the device is difficult to bend, the passability of the device in a delivery sheath that allows the device to reach a target site, or in a biological lumen such as a blood vessel is decreased.

The invention is conceived in view of the aforementioned problems, and an object of the invention is to provide a medical device capable of improving passability in a tubular member or in a biological lumen, and suppressing a decrease in expansion force to widen a biological tissue.

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

In the medical device configured as described above, in the contracted form where the inner tube is extracted from the outer tube, a range where the outer tube and the inner tube overlap each other between the first connecting portion and the second connecting portion is shortened. For this reason, in the contracted form where the expansion body is contracted, the flexibility of the medical device between the first connecting portion and the second connecting portion is improved, and the passability of the medical device in a tubular member such as a sheath or in a biological lumen is improved. In addition, in the medical device, in the reference form where the expansion body is expanded, the range where the outer tube and the inner tube overlap each other between the first connecting portion and the second connecting portion is lengthened. For this reason, in the medical device, the shaft portion is difficult to bend between the first connecting portion and the second connecting portion. For this reason, the medical device can maintain the expansion body in a proper shape in the reference form, so that a decrease in expansion force can be suppressed.

The expansion body may be deformable to be in an expanded form, where the expansion body is expanded in the radial direction, from the reference form by the first connecting portion and the second connecting portion approach each other, and when the expansion body is deformed from the reference form into the expanded form, a part of the inner tube may be stored inside the outer tube from the opening portion. Accordingly, even when a compression force is acted on the expansion body in the axial direction to set the expansion body to the expanded form where the expansion body is more expanded in the radial direction than in the reference form, the shaft portion is difficult to bend between the first connecting portion and the second connecting portion, so that buckling can be suppressed. For this reason, in the medical device, the expansion body is deformable to be in the expanded form of a desired shape that is uniform in a circumferential direction, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction.

The outer tube and/or the inner tube may include a flexible portion having lower flexural rigidity than a portion adjacent to the flexible portion in the axial direction. In the reference form, the flexible portion may be located in a range where the outer tube and the inner tube overlap each other. In the contracted form, the flexible portion may be located in a range different from the range where the outer tube and the inner tube overlap each other. Accordingly, in the contracted form, the flexible portion is located outside the range where the outer tube and the inner tube overlap each other, so that the flexible portion can be flexibly bent. For this reason, in the contracted form, the flexibility of the medical device between the first connecting portion and the second connecting portion is improved, and the passability of the medical device in a tubular member such as a sheath or in a biological lumen is improved. In addition, in the reference form, since the flexible portion is located in the range where the outer tube and the inner tube overlap each other, the medical device is difficult to bend between the first connecting portion and the second connecting portion. Therefore, the medical device can maintain the expansion body in a proper shape in the reference form, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction.

The outer tube may include a first engagement portion. The inner tube may include a second engagement portion. At least in the reference form, the first engagement portion and the second engagement portion may be slidable in the axial direction, and come into contact with each other in a circumferential direction to limit relative rotation between the outer tube and the inner tube. Accordingly, at least in the reference form, relative rotation between the outer tube and the inner tube is limited. For this reason, at least in the reference form, the twisting of the expansion body can be suppressed. Therefore, in the medical device, the expansion body is deformable to be in the reference form of a desired shape, and a decrease in expansion force can be suppressed.

A flexible portion may be formed of a slit portion having a spiral shape or a groove provided in the outer tube and/or in the inner tube. Accordingly, the flexible portion of the outer tube and/or the inner tube can be flexibly bent and easily processed.

A flexible portion may be formed of a plurality of wires. Accordingly, the flexible portion of the outer tube and/or the inner tube can be flexibly bent.

A flexible portion may be formed in a coil shape. Accordingly, the flexible portion of the outer tube and/or the inner tube can be flexibly bent.

A flexible portion may be made of a material softer than a material of a portion adjacent to the flexible portion in the axial direction. Accordingly, the flexible portion of the outer tube and/or the inner tube can be flexibly bent.

Note that dimensional ratios in the drawings may be exaggerated and different from actual ratios for convenience of description. In addition, in the specification, a side on which a medical device <NUM> is inserted into a biological lumen will be referred to as a "distal side", and a side on which operation is performed will be referred to as a "proximal side".

As illustrated in <FIG>, the medical device <NUM> according to the present embodiment is configured to be able to expand a through-hole Hh formed in an atrial septum HA of a heart H of a patient and to perform a maintenance treatment to maintain the size of the expanded through-hole Hh.

As illustrated in <FIG>, the medical device <NUM> of the present embodiment includes a shaft portion <NUM> that is elongate, an expansion body <NUM> provided at a distal portion of the shaft portion <NUM>, a pulling shaft <NUM> that expands the expansion body <NUM>, and an operation unit <NUM> provided at a proximal portion of the shaft portion <NUM>. The expansion body <NUM> is provided with an energy transmission element <NUM> for performing the aforementioned maintenance treatment.

The shaft portion <NUM> includes a main shaft <NUM> that holds the expansion body <NUM> at a distal portion of the main shaft <NUM>, a storage sheath <NUM> that stores the main shaft <NUM>, an outer tube <NUM> connected to the distal portion of the main shaft <NUM>, and an inner tube <NUM> that can be stored in the outer tube <NUM>. The storage sheath <NUM> is movable forward and backward with respect to the main shaft <NUM> in an axial direction. In a state where the storage sheath <NUM> is moved to a distal side of the shaft portion <NUM>, the storage sheath <NUM> can store the expansion body <NUM> thereinside. The storage sheath <NUM> is moved to the proximal side from a state where the expansion body <NUM> is stored, and thus the expansion body <NUM> can be exposed.

A proximal portion of the main shaft <NUM> is connected to the operation unit <NUM>. The distal portion of the main shaft <NUM> is connected to a proximal portion of the expansion body <NUM> and to a proximal portion of the outer tube <NUM>. The outer tube <NUM> extends to the distal side from the distal portion of the main shaft <NUM>.

The pulling shaft <NUM> is stored inside the main shaft <NUM>, the outer tube <NUM>, and the inner tube <NUM>. The pulling shaft <NUM> is a shaft for pulling to act a compression force on the expansion body <NUM>. An axially orthogonal cross section of an outer peripheral surface of the pulling shaft <NUM> is a substantially circular shape. The pulling shaft <NUM> protrudes from a distal end of the inner tube <NUM> to the distal side, and a distal portion of the pulling shaft <NUM> is connected to a distal member <NUM>. A proximal portion of the pulling shaft <NUM> is led out to the proximal side from the operation unit <NUM>. The distal member <NUM> to which the distal portion of the pulling shaft <NUM> is fixed may not be fixed to the expansion body <NUM>. Accordingly, the distal member <NUM> can pull the expansion body <NUM> in a compression direction. In addition, when the expansion body <NUM> is stored in the storage sheath <NUM>, the distal member <NUM> is separated to the distal side from the expansion body <NUM>, so that the expansion body <NUM> can be easily moved in a stretching direction and storability can be improved.

The operation unit <NUM> includes a housing <NUM> to be gripped by an operator, an operation dial <NUM> to be rotationally operable by the operator, and a conversion mechanism <NUM> that operates in conjunction with rotation of the operation dial <NUM>. The pulling shaft <NUM> is held by the conversion mechanism <NUM> inside the operation unit <NUM>. The conversion mechanism <NUM> can move the held pulling shaft <NUM> forward and backward along the axial direction with rotation of the operation dial <NUM>. For example, a rack and pinion mechanism can be used as the conversion mechanism <NUM>.

As illustrated in <FIG>, the expansion body <NUM> includes a plurality of wire portions <NUM> in a circumferential direction. In the present embodiment, four wire portions <NUM> are provided in the circumferential direction. Note that the number of the wire portions <NUM> is not particularly limited. Each of the wire portions <NUM> is expandable and contractable in a radial direction of the expansion body <NUM>. A proximal portion of the wire portion <NUM> is connected to a first connecting portion <NUM> provided at the distal portion of the main shaft <NUM>. The first connecting portion <NUM> located at the proximal portion of the wire portion <NUM> is connected to the proximal portion of the outer tube <NUM> and to the distal portion of the main shaft <NUM>. A second connecting portion <NUM> located at a distal portion of the wire portion <NUM> is connected to a distal portion of the inner tube <NUM>. The distal portion of the wire portion <NUM> extends from the distal portion of the inner tube <NUM> to the proximal side. The wire portion <NUM> is inclined such that the size in the radial direction increases from both end portions toward a central portion in the axial direction. In addition, the wire portion <NUM> includes a holding portion <NUM> having a valley shape in the radial direction of the expansion body <NUM>, at the central portion of the wire portion <NUM> in the axial direction.

The holding portion <NUM> includes a proximal side holding portion <NUM>, and a distal side holding portion <NUM> located closer to the distal side than the proximal side holding portion <NUM>. The holding portion <NUM> further includes a proximal side outward projection portion <NUM>, an inward projection portion <NUM>, and a distal side outward projection portion <NUM>. It is preferable that an interval between the proximal side holding portion <NUM> and the distal side holding portion <NUM> in the axial direction is slightly wider on a radially outward side than on a radially inward side, in a natural state where no external force acts thereon. Accordingly, a biological tissue is easily disposed between the proximal side holding portion <NUM> and the distal side holding portion <NUM> from the radially outward side.

The proximal side holding portion <NUM> includes a projection portion <NUM> protruding toward the distal side. The energy transmission element <NUM> is disposed on the projection portion <NUM>. Note that the proximal side holding portion <NUM> may not include the projection portion <NUM>. Namely, the energy transmission element <NUM> may not protrude to the distal side.

The proximal side outward projection portion <NUM> is located on a proximal side of the proximal side holding portion <NUM>, and is formed in a shape projecting outward in the radial direction. The distal side outward projection portion <NUM> is located on a distal side of the distal side holding portion <NUM>, and is formed in a shape projecting outward in the radial direction. The inward projection portion <NUM> is located between the proximal side holding portion <NUM> and the distal side holding portion <NUM>, and is formed in a shape projecting inward in the radial direction. The proximal side outward projection portion <NUM>, the inward projection portion <NUM>, and the distal side outward projection portion <NUM> are stored in the storage sheath <NUM>, thus being deformable from a projection shape into a shape close to being flat.

In the present embodiment, the energy transmission element <NUM> is provided at the proximal side holding portion <NUM>, but the energy transmission element <NUM> may be provided at the distal side holding portion <NUM>.

Each of the wire portions <NUM> forming the expansion body <NUM> has, for example, a flat plate shape obtained by cutting a cylinder. A wire forming the expansion body <NUM> can have a thickness of <NUM> to <NUM> and a width of <NUM> to <NUM>. However, a wire forming the expansion body <NUM> may have dimensions outside these ranges. In addition, the shape of the wire portion <NUM> is not limited, and may have, for example, a circular cross-sectional shape or other cross-sectional shapes.

Since the energy transmission element <NUM> is provided at the projection portion <NUM> of the proximal side holding portion <NUM>, when the holding portion <NUM> holds the atrial septum HA, energy from the energy transmission element <NUM> is transmitted from a right atrium side to the atrial septum HA. Note that when the energy transmission element <NUM> is provided at the distal side holding portion <NUM>, energy from the energy transmission element <NUM> is transmitted from a left atrium side to the atrial septum HA.

The energy transmission element <NUM> is configured as, for example, a bipolar electrode that receives electric energy from an energy supply device (not illustrated) that is an external device. In this case, energization is performed between the energy transmission elements <NUM> disposed on the wire portions <NUM>. The energy transmission element <NUM> and the energy supply device are connected to each other by a conducting wire (not illustrated) coated with an insulating coating material. The conducting wire is led out to the outside via the shaft portion <NUM> and via the operation unit <NUM>, and is connected to the energy supply device.

Alternatively, the energy transmission element <NUM> may be configured as a monopolar electrode. In this case, energization is performed between the energy transmission element <NUM> and a counter electrode plate prepared outside a body. In addition, the energy transmission element <NUM> may be a heating element (electrode chip) that receives high-frequency electric energy from the energy supply device to generate heat. In this case, energization is performed between the energy transmission elements <NUM> disposed on the wire portions <NUM>. Further, the energy transmission element <NUM> can be configured as an element capable of applying energy to the through-hole Hh, such as an element that exerts a heating or cooling action 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 or the like, and a specific form of the energy transmission element <NUM> is not particularly limited.

The wire portion <NUM> can be made of a metallic material. As the metallic 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 it is better to use an alloy or the like having a spring property such as a nickel-titanium alloy. However, the material for the wire portion <NUM> is not limited to these materials, and the wire portion <NUM> may be made of other materials.

The pulling shaft <NUM> is stored inside the shaft portion <NUM>. A guide wire lumen is formed in the pulling shaft <NUM> and in the distal member <NUM> along the axial direction, and a guide wire <NUM> can be inserted into the guide wire lumen.

Next, the outer tube <NUM> and the inner tube <NUM> will be described. As illustrated in <FIG> and <FIG>, the outer tube <NUM> extends to the distal side from the first connecting portion <NUM> at the proximal portion of the expansion body <NUM>. The outer tube <NUM> includes an open end <NUM> at which an opening portion <NUM> is formed, on the distal side. In addition, a first engagement portion <NUM> having a slit shape and extending from the open end <NUM> to the proximal side along the axial direction is formed in the outer tube <NUM>. The first engagement portion <NUM> has such a width in the circumferential direction that a second engagement portion <NUM> formed in the inner tube <NUM> can enter the first engagement portion <NUM>. It is preferable that the width of the first engagement portion <NUM> in the circumferential direction is widened at a distal portion of the first engagement portion <NUM>. Accordingly, the first engagement portion <NUM> easily receives the second engagement portion <NUM> from the distal side. The outer tube <NUM> includes one first engagement portion <NUM>, but may include two or more first engagement portions <NUM> at different locations in the circumferential direction. In a natural state where no external force acts on the expansion body <NUM>, the expansion body <NUM> is in a reference form where the expansion body <NUM> is deployed in the radial direction. In the reference form, the open end <NUM> is located closer to the distal side than the first connecting portion <NUM>, and is closer to the proximal side than the second connecting portion <NUM>.

In the reference form where the expansion body <NUM> is widened with no external force acting on the expansion body <NUM>, a distance L1 from the first connecting portion <NUM> to the open end <NUM> is <NUM>% to <NUM>% of a distance L2 from the first connecting portion <NUM> to the second connecting portion <NUM>. When the distance L1 is too short, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is shortened, so that the effect of making the shaft portion difficult to bend in the reference form is decreased. When the distance L1 is too long, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is lengthened, so that the effect of making the shaft portion <NUM> easy to bend in a contracted form where the expansion body <NUM> is contracted (refer to <FIG>) is decreased.

The inner tube <NUM> is slidable in the axial direction inside the outer tube <NUM>. The inner tube <NUM> extends to the proximal side from the second connecting portion <NUM> at the distal portion of the expansion body <NUM>. A proximalmost end <NUM> of the inner tube <NUM> is located closer to the proximal side than the open end <NUM> of the outer tube <NUM>. The inner tube <NUM> includes a flexible portion <NUM> that has lower flexural rigidity and is easier to bend than a portion adjacent to the flexible portion <NUM> in the axial direction. The flexible portion <NUM> can be disposed inside the outer tube <NUM> as illustrated in <FIG>, and can be extracted from the outer tube <NUM> to the distal side and disposed closer to the distal side than the outer tube <NUM> as illustrated in <FIG>. The flexible portion <NUM> is formed in a spiral shape by forming a slit portion <NUM> having a spiral shape and penetrating through the flexible portion <NUM> from an outer peripheral surface to an inner peripheral surface. The slit portion <NUM> can be easily formed by, for example, laser processing. Protruding portions <NUM> to be fitted to a recessed portion <NUM> and to a recessed portion <NUM> are formed in surfaces that face each other while interposing the slit portion <NUM> therebetween. The protruding portions <NUM> are widened on a protruding direction side. For this reason, the protruding portion <NUM> has a structure where the protruding portion <NUM> does not come off from the recessed portion <NUM>. Therefore, the flexible portion <NUM> has a structure where the flexible portion <NUM> is easy to bend but is strong against a tensile force. In addition, the second engagement portion <NUM> protruding outward in the radial direction is formed on an outer peripheral surface of the inner tube <NUM>. As illustrated in <FIG>, the second engagement portion <NUM> can slidably enter the first engagement portion <NUM> of the outer tube <NUM>. The second engagement portion <NUM> is formed closer to the distal side than the flexible portion <NUM>, but the position of the second engagement portion <NUM> is not particularly limited. Therefore, the second engagement portion <NUM> may be formed closer to the proximal side than the flexible portion <NUM>, or may be formed to overlap the flexible portion <NUM>.

It is preferable that the storage sheath <NUM> and the main shaft <NUM> of the shaft portion <NUM> are made of a material having a certain degree of flexibility. Examples of such a material include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, and a mixture of two or more thereof, fluororesins such as soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyether blockamide, polyester, polyester elastomer, polyurethane, and polytetrafluoroethylene, polyimide, PEEK, silicone rubber, and latex rubber.

The pulling shaft <NUM> can be made of, for example, an elongate wire such as a metallic material such as stainless steel or a super-elastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, or a resin material having relatively high rigidity. In addition, the pulling shaft <NUM> may be formed by coating the above material with a resin material such as polyvinyl chloride, polyethylene, polypropylene, ethylene-propylene copolymer, or fluororesin.

The distal member <NUM>, the inner tube <NUM>, and the outer tube <NUM> can be made of, for example, a metallic material such as stainless steel or a super-elastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, or a resin material having relatively high rigidity.

Next, a treatment method using the medical device <NUM> according to the present embodiment will be described. The treatment method is performed on a patient suffering from a heart failure (left heart failure). More specifically, as illustrated in <FIG>, the treatment method is performed on a patient suffering from a chronic heart failure in which a myocardium of a left ventricle of the heart H is hypertrophied and increases in stiffness (hardness) to cause an increase in blood pressure in a left atrium HLa.

When the operator forms the through-hole Hh, the operator delivers an introducer in which a guiding sheath and a dilator are combined together, to the vicinity of the atrial septum HA. The introducer can be delivered to, for example, a right atrium HRa via an inferior vena cava Iv. In addition, the introducer can be delivered using the guide wire <NUM>. The operator can insert the guide wire <NUM> into the dilator, and deliver the introducer along the guide wire <NUM>. Note that the insertion of the introducer into or the insertion of the guide wire <NUM> into a living body can be performed using a 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 through the atrial septum HA from a right atrium HRa side toward a left atrium HLa side to form the through-hole Hh. For example, a device such as a wire having a sharp distal end can be used as the puncture device. The puncture device is inserted into the dilator, and is delivered to the atrial septum HA. After the guide wire <NUM> is removed from the dilator, instead of the guide wire <NUM>, the puncture device can be delivered to the atrial septum HA.

Next, the operator delivers the medical device <NUM> to the vicinity of the atrial septum HA along the guide wire <NUM> inserted into the left atrium HLa from the right atrium HRa via the through-hole Hh in advance. At this time, 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. In addition, when the medical device <NUM> is inserted, as illustrated in <FIG>, the expansion body <NUM> is in the contracted form where the expansion body <NUM> is stored in the storage sheath <NUM>. In the contracted form, the proximal side outward projection portion <NUM>, the inward projection portion <NUM>, and the distal side outward projection portion <NUM> that have a projection shape in the reference form are elastically deformed into a shape close to being flat, so that the expansion body <NUM> is contracted in the radial direction. In the contracted form, the flexible portion <NUM> of the inner tube <NUM> is located closer to the distal side than the outer tube <NUM>. For this reason, the flexible portion <NUM> is not covered with the outer tube <NUM>. Accordingly, the flexible portion <NUM> can be flexibly bent. Therefore, as illustrated in <FIG>, when the flexible portion <NUM> is moved in a delivery sheath <NUM> for transporting the distal portion of the medical device <NUM> to a target position in the living body, or in a blood vessel, the flexible portion <NUM> can be easily bent according to the bending of the delivery sheath <NUM> or of the blood vessel. For this reason, the passability of the medical device <NUM> in the delivery sheath <NUM> or in the blood vessel is improved.

Next, the storage sheath <NUM> is moved to the proximal side to expose a distal side portion of the expansion body <NUM> into the left atrium HLa. Accordingly, the distal side portion of the expansion body <NUM> is deployed in the radial direction inside the left atrium HLa by its own restoring force. Next, as illustrated in <FIG> and <FIG>, the storage sheath <NUM> is moved to the proximal side to expose the entirety of the expansion body <NUM>. Accordingly, a proximal side portion of the expansion body <NUM> is deployed in the radial direction inside the right atrium HRa by its own restoring force. At this time, the inward projection portion <NUM> is disposed inside the through-hole Hh. Accordingly, the entirety of the expansion body <NUM> is deployed by its own elastic force, and restores to the original reference form or to a form close to the reference form. At this time, the atrial septum HA is disposed between the proximal side holding portion <NUM> and the distal side holding portion <NUM>. Note that the expansion body <NUM> may come into contact with the through-hole Hh, thereby returning to a shape close to the reference form instead of completely returning 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.

When the expansion body <NUM> is deformed from the contracted state into the reference form, the first connecting portion <NUM> and the second connecting portion <NUM> approach each other. Accordingly, the inner tube <NUM> connected to the second connecting portion <NUM> moves to the proximal side. For this reason, the flexible portion <NUM> of the inner tube <NUM> enters the inside of the outer tube <NUM> from the opening portion <NUM>. For this reason, the flexible portion <NUM> is surrounded by the outer tube <NUM>, and overlaps the outer tube <NUM>. As a result, the flexible portion <NUM> is difficult to bend. In addition, the range in the axial direction where the outer tube <NUM> and the inner tube <NUM> overlap each other is longer in the reference form (refer to <FIG>) and in an expanded form (refer to <FIG>) than in the contracted form (refer to <FIG>). For this reason, the outer tube <NUM> and the inner tube <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> are more difficult to bend in the reference form and in the expanded form than in the contracted form. For this reason, the expansion body <NUM> can be uniformly widened to cause an expansion force to uniformly act on the through-hole Hh of the atrial septum HA.

In addition, when the expansion body <NUM> is in the reference form, the second engagement portion <NUM> protruding from the outer peripheral surface of the inner tube <NUM> is accommodated in the first engagement portion <NUM> having a slit shape which is formed in the outer tube <NUM>. Accordingly, the first engagement portion <NUM> and the second engagement portion <NUM> engage with each other, and the inner tube <NUM> is not rotatable with respect to the outer tube <NUM>. For this reason, it is possible to suppress the twisting of the expansion body <NUM>. For this reason, the expansion body <NUM> can be uniformly widened with a uniform expansion force to cause an expansion force to uniformly act on the through-hole Hh of the atrial septum HA.

Next, the operator operates the operation unit <NUM> in a state where the atrial septum HA is held by the holding portion <NUM>, to move the pulling shaft <NUM> to the proximal side. Accordingly, as illustrated in <FIG> and <FIG>, the expansion body <NUM> receiving a compression force in the axial direction is deformed into the expanded form where the expansion body <NUM> is more expanded in the radial direction than in the reference form. In the expanded form of the expansion body <NUM>, the proximal side holding portion <NUM> and the distal side holding portion <NUM> approach each other, and the atrial septum HA is held between the proximal side holding portion <NUM> and the distal side holding portion <NUM>. The holding portion <NUM> additionally expands in a state where the holding portion <NUM> holds the atrial septum HA, to widen the through-hole Hh in the radial direction.

In the expanded form, similarly to the reference form, the flexible portion <NUM> is surrounded by the outer tube <NUM>, and overlaps the outer tube <NUM>. For this reason, the flexible portion <NUM> is difficult to bend. In addition, since the range in the axial direction where the outer tube <NUM> and the inner tube <NUM> overlap each other is longer in the expanded form than in the contracted form, the outer tube <NUM> and the inner tube <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> are difficult to bend in the expanded form. For this reason, even when the outer tube <NUM> and the inner tube <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> receives a compression force due to pulling of the pulling shaft <NUM>, the outer tube <NUM> and the inner tube <NUM> are difficult to buckle. Therefore, the expansion body <NUM> can be uniformly widened with a uniform expansion force to uniformly widen the through-hole Hh in the radial direction.

In addition, in the expanded form, similarly to the reference form, the first engagement portion <NUM> and the second engagement portion <NUM> engage with each other, and the inner tube <NUM> is not rotatable with respect to the outer tube <NUM>. For this reason, it is possible to suppress the twisting of the expansion body <NUM>. For this reason, the expansion body <NUM> can be uniformly widened with a uniform expansion force to uniformly widen the through-hole Hh in the radial direction.

In the expanded form, when the operator moves the pulling shaft <NUM> further to the proximal side than in the state illustrated in <FIG> and <FIG>, as illustrated in <FIG>, which illustrates an embodiment not falling under the scope of the invention, the open end <NUM> that is a distal side end portion of the outer tube <NUM> abuts against the second connecting portion <NUM>. Accordingly, a relative movement between the outer tube <NUM> and the inner tube <NUM> is limited, and excessive expansion of the expansion body <NUM> is limited. As a result, excessive expansion of the through-hole Hh can be limited, and safety can be improved. Note that the proximalmost end <NUM> of the inner tube <NUM> may abut against, for example, a structure protruding from an inner peripheral surface of the outer tube <NUM> before the open end <NUM> of the outer tube <NUM> abuts against the second connecting portion <NUM> when the operator moves the pulling shaft <NUM> to the proximal side. Even with such a configuration, a relative movement between the outer tube <NUM> and the inner tube <NUM> can be limited, and excessive expansion of the expansion body <NUM> can be limited. As a result, excessive expansion of the through-hole Hh can be limited, and safety can be improved.

After the through-hole Hh is expanded, hemodynamics is confirmed. As illustrated in <FIG>, the operator delivers a hemodynamics confirmation device <NUM> to the right atrium HRa via the inferior vena cava Iv. For example, a known echo catheter can be used as the hemodynamics confirmation device <NUM>. The operator can cause a display device such as a display to display an echo image acquired by the hemodynamics confirmation device <NUM>, and confirm the amount of blood passing through the through-hole Hh, based on a display result.

Next, the operator performs a maintenance treatment to maintain 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 transmission element <NUM>, so that the edge portion of the through-hole Hh is cauterized (heated and cauterized) by the energy. When a biological tissue in the vicinity of the edge portion of the through-hole Hh is cauterized through the energy transmission element <NUM>, a degenerated portion in which the biological tissue is degenerated is formed in the vicinity of the edge portion. Since the biological tissue in the degenerated portion is in a state where elasticity is lost, the through-hole Hh can maintain a shape when the through-hole Hh is widened by the expansion body <NUM>.

In the expanded form, as described above, since the expansion body <NUM> is uniformly widened with a uniform expansion force, the energy transmission element <NUM> provided in each of the wire portions <NUM> is properly pressed against the atrial septum HA. In addition, the energy transmission element <NUM> is disposed on the projection portion <NUM> of the proximal side holding portion <NUM>. For this reason, the maintenance treatment is performed in a state where the energy transmission element <NUM> is buried in the biological tissue by pressing the projection portion <NUM> against the atrial septum HA. Accordingly, the energy transmission element <NUM> does not come into contact with the blood during the maintenance treatment, so that it is possible to suppress the generation of blood clots or the like caused by the leakage of a current to the blood.

After the maintenance treatment, hemodynamics is confirmed again, and when the amount of the blood passing through the through-hole Hh reaches a desired amount, the operator reduces the expansion body <NUM> in diameter. The operator moves the storage sheath <NUM> with respect to the expansion body <NUM> in a distal end direction. Accordingly, the expansion body <NUM> is stored in the storage sheath <NUM> from the proximal side, and is in the contracted form. Further, the operator removes the entirety of the medical device <NUM> out of the living body to end the treatment.

As described above, the medical device <NUM> according to the aforementioned embodiment is a medical device including: the elongated shaft portion <NUM>; and the expansion body <NUM> provided at the distal portion of the shaft portion <NUM> to be expandable and contractable in a radial direction. The shaft portion <NUM> includes the outer tube <NUM>, and the inner tube <NUM> that is slidable in the axial direction inside the outer tube <NUM>. The expansion body <NUM> includes the first connecting portion <NUM> connected to the outer tube <NUM>, and the second connecting portion <NUM> connected to the inner tube <NUM>. The outer tube <NUM> includes the open end <NUM> at which the opening portion <NUM> is formed, the inner tube <NUM> entering and exiting from the opening portion <NUM>. The expansion body <NUM> is deformable to be in the reference form where the expansion body <NUM> is widened in the radial direction in a natural state, and is deformable to be in the contracted form where the expansion body <NUM> is contracted in the radial direction, when the first connecting portion <NUM> and the second connecting portion <NUM> are more separated from each other in the contracted form than in the reference form. In the reference form, the open end <NUM> is located between the first connecting portion <NUM> and the second connecting portion <NUM>, and when the expansion body <NUM> is deformed from the reference form into the contracted form, a part of the inner tube <NUM> is extracted from the opening portion <NUM>. Accordingly, in the medical device <NUM>, in the contracted form where the inner tube <NUM> is extracted from the outer tube <NUM>, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is shortened. For this reason, in the contracted form where the expansion body <NUM> is contracted, the flexibility of the medical device <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> is improved, and the passability of the medical device <NUM> in a tubular member such as the delivery sheath <NUM> or in a biological lumen is improved. In addition, in the medical device <NUM>, in the reference form where the expansion body <NUM> is expanded, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is lengthened. For this reason, in the medical device <NUM>, the shaft portion <NUM> is difficult to bend between the first connecting portion <NUM> and the second connecting portion <NUM>. For this reason, the medical device <NUM> can maintain the expansion body <NUM> in a proper shape in the reference form, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction. Note that the first connecting portion <NUM> of the expansion body <NUM> may be directly connected to the outer tube <NUM> or may be indirectly connected to the outer tube <NUM> via another member. In addition, the second connecting portion <NUM> of the expansion body <NUM> may be directly connected to the inner tube <NUM> or may be indirectly connected to the inner tube <NUM> via another member.

In addition, the expansion body <NUM> is deformable to be in the expanded form, where the expansion body <NUM> is expanded in the radial direction, from the reference form by the first connecting portion <NUM> and the second connecting portion <NUM> approaching each other, and when the expansion body <NUM> is deformed from the reference form into the expanded form, a part of the inner tube <NUM> is stored inside the outer tube <NUM> from the opening portion <NUM>. Accordingly, even when a compression force is acted on the expansion body <NUM> in the axial direction to set the expansion body <NUM> to the expanded form where the expansion body <NUM> is more expanded in the radial direction than in the reference form, the shaft portion <NUM> is difficult to bend between the first connecting portion <NUM> and the second connecting portion <NUM>, so that buckling can be suppressed. For this reason, in the medical device <NUM>, the expansion body <NUM> is deformable to be in the expanded form of a desired shape that is uniform in the circumferential direction, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction.

In addition, the inner tube <NUM> includes the flexible portion <NUM> having lower flexural rigidity than a portion adjacent to the flexible portion <NUM> in the axial direction. In the reference form, the flexible portion <NUM> is located in a range where the outer tube <NUM> and the inner tube <NUM> overlap each other. In the contracted form, the flexible portion <NUM> is located in a range different from the range where the outer tube <NUM> and the inner tube <NUM> overlap each other. Accordingly, in the contracted form, the flexible portion <NUM> is located outside the range where the outer tube <NUM> and the inner tube <NUM> overlap each other, so that the flexible portion <NUM> can be flexibly bent. For this reason, in the contracted form, the flexibility of the medical device <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> is improved, and the passability of the medical device <NUM> in a tubular member such as the delivery sheath <NUM> or in a biological lumen is improved. In addition, in the reference form, since the flexible portion <NUM> is located in the range where the outer tube <NUM> and the inner tube <NUM> overlap each other, the medical device <NUM> is difficult to bend between the first connecting portion <NUM> and the second connecting portion <NUM>. Therefore, the medical device <NUM> can maintain the expansion body <NUM> in a proper shape in the reference form, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction.

In addition, the outer tube <NUM> includes the first engagement portion <NUM>. The inner tube <NUM> includes the second engagement portion <NUM>. At least in the reference form, the first engagement portion <NUM> and the second engagement portion <NUM> are slidable in the axial direction, and come into contact with each other in the circumferential direction to limit relative rotation between the outer tube <NUM> and the inner tube <NUM>. Accordingly, at least in the reference form, relative rotation between the outer tube <NUM> and the inner tube <NUM> is limited. For this reason, at least in the reference form, the twisting of the expansion body <NUM> can be suppressed. Therefore, in the medical device <NUM>, the expansion body <NUM> is deformable to be in the reference form of a desired shape, and a decrease in expansion force can be suppressed.

In addition, the flexible portion <NUM> is formed of the slit portion <NUM> having a spiral shape provided in the inner tube <NUM>. Accordingly, the flexible portion <NUM> can be flexibly bent and easily processed.

The medical device according to the invention may be used in a treatment method. in which the through-hole Hh that is opened in a biological tissue is widened using the medical device <NUM>, in which the medical device <NUM> includes the elongated shaft portion <NUM>, and the expansion body <NUM> provided at the distal portion of the shaft portion <NUM> to be expandable and contractable in the radial direction, the shaft portion <NUM> includes the outer tube <NUM>, and the inner tube <NUM> that is slidable in the axial direction inside the outer tube <NUM>, the expansion body <NUM> includes the first connecting portion <NUM> connected to the outer tube <NUM>, and the second connecting portion <NUM> connected to the inner tube <NUM>, the outer tube <NUM> includes the open end <NUM> at which the opening portion <NUM> is formed, the inner tube <NUM> entering and exiting from the opening portion <NUM>, and the expansion body <NUM> is able to be in the reference form where the expansion body <NUM> is widened in the radial direction, and is able to be in the contracted form where the expansion body <NUM> is contracted in the radial direction, when the first connecting portion <NUM> and the second connecting portion <NUM> are more separated from each other than in the reference form, the method including: transporting the expansion body <NUM> in a living body and inserting the expansion body <NUM> into the through-hole Hh that is opened in the biological tissue, with the expansion body <NUM> set to the contracted form; and widening the through-hole Hh using the expansion body <NUM> with the expansion body <NUM> set to the reference form inside the through-hole Hh.

In the treatment method configured as described above, in the contracted form where the inner tube <NUM> is extracted from the outer tube <NUM>, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is shortened. For this reason, according to the treatment method, in the contracted form where the expansion body <NUM> is contracted, flexibility between the first connecting portion <NUM> and the second connecting portion <NUM> is improved, and passability in a tubular member such as the delivery sheath <NUM> or in a biological lumen is improved. In addition, in the reference form where the expansion body <NUM> is expanded, the range where the outer tube <NUM> and the inner tube <NUM> overlap each other between the first connecting portion <NUM> and the second connecting portion <NUM> is lengthened. For this reason, in the medical device <NUM>, the shaft portion <NUM> is difficult to bend between the first connecting portion <NUM> and the second connecting portion <NUM>. For this reason, according to the treatment method, the expansion body <NUM> can be maintained in a proper shape in the reference form, so that a decrease in expansion force can be suppressed and a biological tissue can be uniformly widened in the radial direction.

Note that the invention is not limited only to the aforementioned embodiment and various modifications can be made by those skilled in the art without departing from the technical concept of the invention. For example, the biological lumen to which the medical device <NUM> is applied is not limited to blood vessels, and may be, for example, a vessel, a ureter, a bile duct, an ovarian duct, a hepatic duct, a lymph duct, or the like.

In addition, as in a first modification example illustrated in <FIG>, a flexible portion <NUM> may be formed not in the inner tube <NUM> but in the outer tube <NUM>. The flexible portion <NUM> is formed of, for example, a plurality of slit portions <NUM>. In the contracted form, as illustrated in <FIG>, the flexible portion <NUM> of the outer tube <NUM> is disposed at a position where the flexible portion <NUM> does not overlap the inner tube <NUM> in the axial direction. For this reason, the flexible portion <NUM> of the outer tube <NUM> can be easily bent. In addition, in the reference form and in the expanded form, as illustrated in <FIG>, the flexible portion <NUM> of the outer tube <NUM> is disposed at a position where the flexible portion <NUM> overlaps the inner tube <NUM> in the axial direction. For this reason, the flexible portion <NUM> of the outer tube <NUM> is difficult to bend. In addition, the medical device <NUM> may include both the inner tube <NUM> including the flexible portion <NUM> illustrated in <FIG>, and the outer tube <NUM> including the flexible portion <NUM> illustrated in <FIG>.

In addition, both the inner tube <NUM> and the outer tube <NUM> may not include the flexible portion <NUM>. The range in the axial direction where the outer tube <NUM> and the inner tube <NUM> overlap each other is longer in the reference form (refer to <FIG>) and in the expanded form (refer to <FIG>) than in the contracted form (refer to <FIG>). For this reason, even when the outer tube <NUM> and the inner tube <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> do not include the flexible portion <NUM>, bending is more difficult in the reference form and in the expanded form than in the contracted form.

In addition, as in a second modification example illustrated in <FIG>, the outer tube <NUM> may be connected to the second connecting portion <NUM>, and the inner tube <NUM> may be connected to the first connecting portion <NUM>.

In addition, as in a third modification example illustrated in <FIG>, the medical device <NUM> may not include the expansion body <NUM> (in which case it would not fall under the scope of the claims). The distal portion of the pulling shaft <NUM> is connected to the inner tube <NUM>. When an operator pulls the pulling shaft <NUM>, as illustrated in <FIG>, the medical device <NUM> is set to the accommodated form where at least a part of the inner tube <NUM> including the flexible portion <NUM> is disposed at a position where at least the part overlaps the outer tube <NUM>. In addition, when the operator pushes the pulling shaft <NUM>, as illustrated in <FIG>, the medical device <NUM> is set to the extended form where the flexible portion <NUM> of the inner tube <NUM> is disposed at a position where the flexible portion <NUM> does not overlap the outer tube <NUM>.

As described above, the medical device <NUM> according to the third modification example includes the elongated shaft portion <NUM>. The shaft portion <NUM> includes the outer tube <NUM>, and the inner tube <NUM> that is slidable in the axial direction inside the outer tube <NUM>. The outer tube <NUM> includes the open end <NUM> at which the opening portion <NUM> is formed, the inner tube <NUM> entering and exiting from the opening portion <NUM>. The shaft portion <NUM> is able to be in the accommodated form where at least a part of the inner tube <NUM> is accommodated in the outer tube <NUM>, and is able to be in the extended form where the inner tube <NUM> is extracted from the opening portion <NUM> from the accommodated form. The outer tube <NUM> and/or the inner tube <NUM> includes the flexible portion <NUM> having lower flexural rigidity than a portion adjacent to the flexible portion <NUM> in the axial direction. In the accommodated form, the flexible portion <NUM> is located in a range where the outer tube <NUM> and the inner tube <NUM> overlap each other, and in the extended form, the flexible portion <NUM> is located in a range different from the range where the outer tube <NUM> and the inner tube <NUM> overlap each other. Accordingly, in the extended form, the flexible portion <NUM> is located outside the range where the outer tube <NUM> and the inner tube <NUM> overlap each other, so that the flexible portion <NUM> can be flexibly bent. For this reason, in the extended form, the flexibility of the medical device <NUM> between the first connecting portion <NUM> and the second connecting portion <NUM> is improved, and the passability of the medical device <NUM> in a tubular member such as the delivery sheath <NUM> or in a biological lumen is improved. In addition, in the accommodated form, the flexible portion <NUM> is located in the range where the outer tube <NUM> and the inner tube <NUM> overlap each other. For this reason, in the accommodated form, it is possible to make the medical device <NUM> difficult to bend between the first connecting portion <NUM> and the second connecting portion <NUM>. The medical device <NUM> can be, for example, a catheter that bends easily until the catheter reaches a stenosed site and is difficult to bend at the stenosed site to exert a strong pushing force, a catheter that forms a bent or meandering lumen into a linear shape, and the like.

In addition, the form of the flexible portion <NUM> is not particularly limited as long as the flexible portion <NUM> is more flexible than a portion adjacent to the flexible portion <NUM> in the axial direction. For example, the flexible portion <NUM> may be formed as a non-through groove in the inner peripheral surface and/or in the outer peripheral surface of the inner tube <NUM> or the outer tube <NUM>. In addition, as illustrated in <FIG>, the flexible portion <NUM> may be a slit portion or a non-through groove that is formed to extend in the circumferential direction instead of having a spiral shape. In addition, as illustrated in <FIG>, the flexible portion <NUM> may be a plurality of through-holes or a plurality of non-through holes. In addition, as illustrated in <FIG>, the flexible portion <NUM> may be formed to be thinner than a portion adjacent to the flexible portion <NUM> in the axial direction. In addition, as illustrated in <FIG>, the flexible portion <NUM> may be formed in a coil shape. In addition, as illustrated in <FIG>, the flexible portion <NUM> may be formed by twisting or knitting a plurality of wires. In addition, the flexible portion <NUM> may be made of a material softer than the material of a portion adjacent to the flexible portion <NUM> in the axial direction. The hardness (softness) of the material can be specified by, for example, Rockwell hardness, Brinnel hardness, Vickers hardness, Shore hardness, durometer hardness, and the like.

In addition, the inner tube <NUM> may be connected to the second connecting portion <NUM> so as to be slightly movable. In addition, the outer tube <NUM> may be connected to the first connecting portion <NUM> so as to be slightly movable.

Claim 1:
A medical device (<NUM>) comprising:
an elongated shaft portion (<NUM>); and
an expansion body (<NUM>) provided at a distal portion of the shaft portion (<NUM>) to be expandable and contractable in a radial direction,
wherein the shaft portion (<NUM>) includes an outer tube (<NUM>), and an inner tube (<NUM>) that is slidable in an axial direction inside the outer tube (<NUM>),
the expansion body (<NUM>) includes a first connecting portion (<NUM>) connected to the outer tube (<NUM>), and a second connecting portion (<NUM>) connected to the inner tube (<NUM>),
the outer tube (<NUM>) includes an open end (<NUM>) at which an opening portion (<NUM>) is formed, the inner tube (<NUM>) entering and exiting from the opening portion (<NUM>),
the expansion body (<NUM>) is deformable to be in a reference form in which the expansion body (<NUM>) is widened in the radial direction in a natural state, and is deformable to be in a contracted form in which the expansion body (<NUM>) is contracted in the radial direction by the first connecting portion (<NUM>) and the second connecting portion (<NUM>) being more separated from each other in the contracted form than in the reference form, and
in the reference form, the open end (<NUM>) is located between the first connecting portion (<NUM>) and the second connecting portion (<NUM>) and when the expansion body (<NUM>) is deformed from the reference form into the contracted form, a part of the inner tube (<NUM>) is extracted from the opening portion (<NUM>),
characterized in that
in the reference form where the expansion body (<NUM>) is widened with no external force acting on the expansion body (<NUM>), a distance L1 from the first connecting portion (<NUM>) to the open end (<NUM>) is <NUM>% to <NUM>% of a distance L2 from the first connecting portion (<NUM>) to the second connecting portion (<NUM>).