Patent Description:
In particular, the present invention relates to a medical device according to the preamble of claim <NUM>,such as it is e.g. known from <CIT>, <CIT> or <CIT>.

As a medical device, a device that performs an irreversible electroporation (IRE) treatment is known. The irreversible electroporation has attracted attention since the treatment is non-thermal and can suppress damage to surrounding blood vessels or nerves. For example, a medical device is known in which a cancer that is less likely to be removed by surgery is treated by using the irreversible electroporation.

For atrial fibrillation caused by abnormal excitement appearing in a myocardial sleeve of a pulmonary vein wall, pulmonary vein isolation may be performed to destroy myocardial cells by ablating a joint portion between a pulmonary vein and a left atrium. In the pulmonary vein isolation, high frequency waves are generated from a distal end of an ablation catheter to cauterize and necrotize a myocardium in a dot shape. The ablation catheter is moved to cauterize an inflow portion of the pulmonary vein in a circumferential shape, and isolates the pulmonary vein.

For example, PTL <NUM> discloses a device in which a ring-shaped electrode is provided on an outer peripheral surface of an elongated tube body. A conductor for supplying a current to the electrode is spirally disposed inside the tube body.

It is desirable that a device inserted into a biological lumen has a reduced diameter so that the device can be inserted into a narrow biological lumen. However, according to the device disclosed in PTL <NUM> described above, an electrode is located outside a tube body with respect to a conductor in a radial direction. Therefore, it is difficult to reduce a diameter of the device inserted into a living body.

The present invention is made to solve the above-described problem, and an object thereof is to provide a medical device which can be inserted into a narrow biological lumen and can effectively ablate a wide range.

In order to achieve the above-described object, there is provided a medical device according to claim <NUM>. The dependent claims realte to advantaegous embodiments.

According to the medical device configured as described above, the electrode portion does not protrude outward in the radial direction, and can have a reduced diameter. Therefore, the medical device can be inserted into a narrow biological lumen, and a wide range can be effectively ablated by the electrode portion curved in the radial direction.

Dimensions in the drawings are exaggerated and different from actual dimensions for convenience of description, in some cases. In addition, in the description herein and the drawings, the same reference numerals will be assigned to configuration elements having substantially the same functional configuration, and thus, repeated description will be omitted. In the description herein, a side where a device is inserted into a lumen will be referred to as a "distal side", and an operating hand-side will be referred to as a "proximal side".

A medical device <NUM> according to a first embodiment is percutaneously inserted into a biological lumen, comes into contact with a biological tissue of a target site, and applies an electric signal to perform irreversible electroporation. A target of the medical device <NUM> of the present embodiment is an electroporation treatment performed over an entire periphery of an entrance portion of a pulmonary vein in pulmonary vein isolation. However, the medical device <NUM> is also applicable to other treatments.

As illustrated in <FIG>, the medical device <NUM> has an elongated shaft portion <NUM>, a balloon <NUM> which is an expansion body provided in a distal portion of the shaft portion <NUM>, and a hub <NUM> provided in a proximal portion of the shaft portion <NUM>. Furthermore, the medical device <NUM> has a plurality of electrode portions <NUM> provided around the balloon <NUM> and a conductor <NUM> that transmits a current to the electrode portions <NUM>.

The shaft portion <NUM> has a tubular outer tube <NUM> and an inner tube <NUM> disposed inside a first tube body <NUM>. The outer tube <NUM> and the inner tube <NUM> are disposed coaxially with each other. The outer tube <NUM> and the inner tube <NUM> are relatively movable in an axial direction. The outer tube <NUM> has a tubular first tube body <NUM> and a second tube body <NUM> which covers an outer peripheral surface of the first tube body <NUM> and is fixed to the first tube body <NUM>. The conductor <NUM> is disposed to be interposed between the first tube body <NUM> and the second tube body <NUM>. The first tube body <NUM> and the second tube body <NUM> are disposed coaxially with each other. The first tube body <NUM> has a step portion <NUM> extending to a distal side further than a distal surface <NUM> of the second tube body <NUM>. The step portion <NUM> has a circular tube shape. A proximal portion of the balloon <NUM> is fixed to an outer peripheral surface of the step portion <NUM>. In addition, a connection section <NUM> between the electrode portion <NUM> and the conductor <NUM> may be disposed on the outer peripheral surface of the step portion <NUM>. In addition, the conductors <NUM> are likely to be equally disposed in a circumferential direction Z since the conductors <NUM> are disposed on an outer surface of the first tube body <NUM> disposed inside the second tube body <NUM>.

A guide wire lumen <NUM> extending along a length direction is formed inside the inner tube <NUM>. A guide wire can be inserted into the guide wire lumen <NUM>. An inflation lumen <NUM> is formed inside the outer tube <NUM> and outside the inner tube <NUM>. An inflation fluid for inflating the balloon <NUM> can flow through the inflation lumen <NUM>. The inflation fluid may be gas or a liquid. For example, it is possible to use gas such as helium gas, CO<NUM> gas, O<NUM> gas, and laughter gas, or a liquid such as a physiological salt solution, a contrast agent, and a mixture thereof.

The inner tube <NUM> further extends to a distal side than a distal end of the first tube body <NUM>. A distal portion of the balloon <NUM> is fixed to an outer peripheral surface of the inner tube <NUM> on a distal side from the first tube body <NUM>. In the inner tube <NUM>, a fixing portion <NUM> for fixing a distal portion of the electrode portion <NUM> is fixed to an outer peripheral surface on a distal side from a position where the balloon <NUM> is fixed.

An outer diameter of the shaft portion <NUM> is not particularly limited. However, it is preferable that the outer diameter is minimally invasive and is not excessively large to satisfy compatibility with a general sheath or a guiding catheter to be inserted. For example, the outer diameter is <NUM> or smaller, and is preferably <NUM> or smaller.

It is preferable that a material for forming the first tube body <NUM>, the second tube body <NUM>, and the inner tube <NUM> has flexibility to some degrees. In addition, it is preferable that the material for forming of the first tube body <NUM>, the second tube body <NUM>, and the inner tube <NUM> has an insulation property. Examples of the material include polyolefin such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, and a mixture of two or more types thereof, and soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyimide, polyester, polyester elastomer, polyurethane, fluororesin such as polytetrafluoroethylene, silicone rubber, and latex rubber.

The balloon <NUM> is flexible and deformable. A shape of the balloon <NUM> is not particularly limited. However, for example, the shape may be a cylinder, an ellipsoid, or a trapezoid. The distal portion of the balloon <NUM> is fixed to the outer peripheral surface of the distal portion of the inner tube <NUM>. The proximal portion of the balloon <NUM> is fixed to the outer peripheral surface of the distal portion of the first tube body <NUM>. It is preferable that the balloon <NUM> has a thin film shape and flexibility. In addition, the balloon <NUM> needs to be strong enough to reliably spread the electrode portion <NUM>. As a material for forming the balloon <NUM>, the above-described materials for forming the shaft portion <NUM> can be used. Alternatively, it is possible to use other materials (for example, various elastomer materials such as hydrogenated styrene-based thermoplastic elastomer (SEBS)).

The conductor <NUM> has a linear shape. As illustrated in <FIG>, the conductor <NUM> has a buried portion <NUM> buried inside the outer tube <NUM>, a protruding portion <NUM> protruding in a distal direction from the distal surface <NUM> of the outer tube <NUM>, and a lead-out portion <NUM> which is led out from the outer tube <NUM> on the proximal side. The buried portion <NUM> is interposed between the first tube body <NUM> and the second tube body <NUM>. The buried portion <NUM> is located outside an inner peripheral surface of the outer tube <NUM>, and is located inside the outer peripheral surface. For example, a wire rod serving as the conductor <NUM> is wound around the outer peripheral surface of the first tube body <NUM> and the second tube body <NUM> is extruded outward. In this manner, the buried portion <NUM> is buried in the outer tube <NUM>. It is preferable that the buried portion <NUM> is covered by a material of the outer tube <NUM> formed of an insulation material without any gap. In this manner, it is possible to reliably suppress electrical short-circuit of the buried portions <NUM> which may come into contact with each other. The number of the conductors <NUM> is equal to or more than the number of the electrode portions <NUM>. In this manner, the conductor <NUM> can transmit an independent current to all of the electrode portions <NUM>. In the present embodiment, the number of the conductors <NUM> is the same as the number of the electrode portions <NUM> (for example, <NUM>). The plurality of conductors <NUM> are formed in a structure which is spirally wound multiple times. The plurality of conductors <NUM> are disposed away from each other at an equal interval. Therefore, the plurality of the conductors <NUM> can transmit the independent current without any electrical short-circuit. A separation distance between the conductors <NUM> is preferably set in accordance with a supplied electric signal so that the electrical short-circuit does not occur. For example, when an electric signal of <NUM>,<NUM> V is applied, the separation distance between the conductors <NUM> is preferably <NUM> or longer. In this manner, it is possible to improve electrical safety of the medical device <NUM>.

When a radius (distance) from an axis X of the shaft portion <NUM> to a central axis Y of the conductor <NUM> is defined as R, the number of the conductors <NUM> is defined as N, and a tilting angle of the conductor <NUM> with respect to a cross section orthogonal to the axis X of the shaft portion <NUM> is defined as θ, a distance D between the central axes Y of the adjacent conductors <NUM> is 2πR/N·sinθ.

For example, the radius R is <NUM> to <NUM>. For example, the number N is <NUM> to <NUM>. For example, the tilting angle θ is <NUM> to <NUM> degrees. For example, the distance D is <NUM> to <NUM>.

The protruding portion <NUM> is substantially parallel to the axis X, and is connected to the proximal portion of the electrode portion <NUM>. At least a portion of the protruding portion <NUM> is perpendicular to the circumferential direction Z of the shaft portion <NUM>. That is, at least a portion of the protruding portion <NUM> is parallel to the axis X of the shaft portion, when a development view of the shaft portion <NUM> developed in the circumferential direction Z is viewed from the outside in the radial direction of the shaft portion <NUM> (refer to <FIG>). Therefore, when the protruding portion <NUM> protrudes in the distal direction from the buried portion <NUM> spirally wound inside the outer tube <NUM> through the distal surface <NUM>, the angle is changed, and the protruding portion is substantially parallel to the axis X. The protruding portion <NUM> may not be parallel to the axis X. For example, the protruding portion <NUM> may be tilted in the distal direction to be closer to the axis X of the shaft portion <NUM>. Even in this case, the protruding portion <NUM> can be perpendicular to the circumferential direction Z. The distal end of the protruding portion <NUM> is located on the proximal side from the distal end of the step portion <NUM>. Therefore, the proximal portion of the protruding portion <NUM> and the electrode portion <NUM> is stably disposed on an outer surface of the step portion <NUM>.

The lead-out portion <NUM> is drawn out in a proximal direction from the proximal portion of the second tube body <NUM>, and is connected to a power source unit <NUM> provided outside the shaft portion <NUM>. The power source unit <NUM> can supply electricity to the electrode portion <NUM>.

A material for forming the conductor <NUM> is preferably highly conductive. For example, copper, gold, platinum, silver, aluminum, alloy, or carbon fiber may be used. As the conductor <NUM>, a known lead wire can be used.

As illustrated in <FIG> and <FIG>, each of the electrode portions <NUM> is located on an outer peripheral side of the balloon <NUM>, and is not fixed to the balloon <NUM>. The electrode portion <NUM> may be fixed to the balloon <NUM>. The electrode portion <NUM> is formed of a wire rod which is conductive and flexible. The plurality of electrode portions <NUM> are disposed to be aligned in the circumferential direction Z of the balloon <NUM> on the outer peripheral side of the balloon <NUM>. Each of the electrode portions <NUM> extends in the length direction of the shaft portion <NUM>. The electrode portion <NUM> includes a curved portion <NUM> that can be curved in the radial direction of the shaft portion <NUM>. The electrode portion <NUM> has an electrode proximal portion <NUM> on the proximal side from the balloon <NUM> and an electrode distal portion <NUM> on the distal side from the balloon <NUM>.

A proximal end of the electrode proximal portion <NUM> is in contact with and joined to a distal end of the protruding portion <NUM> of the conductor <NUM>. In this manner, the electrode portion <NUM> is electrically connected to the conductor <NUM>. The connection section <NUM> between the electrode proximal portion <NUM> and the protruding portion <NUM> which are provided in each of the electrode portions <NUM> is covered by an insulation tube <NUM> formed of an insulation material. A joining method is not limited as long as the method enables electrical conduction. For example, soldering, laser fusion, welding using various metal braces, bonding using a conductive adhesive, or mechanical interlocking using a chuck may be used. The plurality of connection sections <NUM>, the insulation tube <NUM>, and the protruding portion <NUM> which are aligned on the outer peripheral surface of the step portion <NUM> are collectively covered by a single protective tube <NUM> formed of an insulation material. Therefore, the connection section <NUM> and the protruding portion <NUM> are covered by the insulation tube <NUM> and/or the protective tube <NUM> on the distal side from the distal surface <NUM>, and are not exposed outward. In this manner, it is possible to improve electrical safety of the medical device <NUM>. As a material for forming the insulation tube <NUM> and the protective tube <NUM>, the above-described materials for forming the shaft portion <NUM> can be used.

The electrode distal portion <NUM> is fixed to the fixing portion <NUM> provided on the distal side from the balloon <NUM> of the inner tube <NUM>. A cross-sectional shape orthogonal to the length direction of each of the electrode portions <NUM> is rectangular. That is, the cross-sectional shape orthogonal to the length direction of the electrode portion <NUM> is a shape formed so that in at least a portion of the electrode portion <NUM>, the length along the circumferential direction Z of the balloon <NUM> is longer than the length along the radial direction of the balloon <NUM>. Therefore, a long side of the cross section extends along the circumferential direction Z of the balloon <NUM>. In this manner, the plurality of electrode portions <NUM> aligned in the circumferential direction Z of the balloon <NUM> are likely to be bent in the radial direction of the balloon <NUM>, and are less likely to deform in a direction in which the electrode portions <NUM> are closer to each other. Therefore, it is possible to suppress electrical short-circuit or entanglement between the electrode portions <NUM>. A cross-sectional shape of the electrode portion <NUM> is not limited to a rectangle, and for example, may be a circle, a semicircle, an ellipse, or a square.

As a material for forming the electrode portion <NUM>, for example, superelastic metal represented by a Ni-Ti alloy can be preferably used. However, the electrode portion <NUM> may be formed of a conductive material other than the above-described material. For example, the electrode portion <NUM> may be conductive rubber. Furthermore, the electrode portion <NUM> may be formed of a flexible printed circuit board (FPC).

In the electrode portion <NUM>, the outer surface other than the curved portion <NUM> is coated with an insulation material. The insulation material is not electrically conductive. The insulation material may be provided on a side where the outer surface of the electrode portion <NUM> is not in contact with the biological tissue, that is, a side that faces the balloon <NUM>.

In the present embodiment, <NUM> electrode portions <NUM> are equally provided in the circumferential direction Z. However, the number of the electrode portions <NUM> may be larger or smaller than <NUM>. An electric signal is applied between the adjacent electrode portions <NUM>. However, an electrode (alternatively, a counter electrode) may be disposed outside a body, and the electric signal may be applied between the electrode (alternatively, the counter electrode) outside the body and the electrode portion <NUM>.

As illustrated in <FIG>, the proximal portion of the inner tube <NUM> is interlocked with the hub <NUM>. The first tube body <NUM> located outside the inner tube <NUM> and movable in the axial direction with respect to the inner tube <NUM> is interlocked with the hub <NUM> to be slidable. The hub <NUM> has a first port <NUM> having an opening communicating with the guide wire lumen <NUM> and a second port <NUM> having an opening communicating with the inflation lumen <NUM>.

Next, an unclaimed treatment method using the medical device <NUM> will be described. First, an introducer (not illustrated) percutaneously punctures the blood vessel. Next, after a guide wire (not illustrated) is inserted into a guiding catheter (not illustrated), the guiding catheter is inserted into the introducer. Next, the guide wire is protruded to the distal side, and thereafter, a distal portion of the guiding catheter is inserted into the blood vessel through a distal portion opening of the introducer. Thereafter, while the guide wire is moved ahead, the guiding catheter is gradually pushed to a target site. An operator forms a through-hole in an atrial septum by penetrating a predetermined puncture device from a right atrium side toward a left atrium side. For example, as the puncture device, it is possible to use a device such as a wire having a sharp distal end. The puncture device can be delivered via the guiding catheter. In addition, for example, the puncture device can be delivered into the atrial septum instead of the guide wire after the guide wire is removed from the guiding catheter. A specific structure of the puncture device used for penetrating the atrial septum, and a specific procedure for forming the through-hole is not particularly limited. After the through-hole is formed, the operator uses a dilator to widen the through-hole. Next, the operator causes the guiding catheter to pass through the through-hole, and uses the guide wire to push the guiding catheter forward to the target site (for example, vicinity of the pulmonary vein).

Next, an end of the guide wire is inserted into a distal opening portion of the guide wire lumen <NUM> of the shaft portion <NUM>, and the guide wire is pulled out from the first port <NUM> of the hub <NUM>. Next, the medical device <NUM> is inserted from the distal portion into the guiding catheter inserted into the blood vessel, and the medical device is pushed forward along the guide wire. At this time, a ring catheter provided with an electrode may be used instead of the guide wire.

As illustrated in <FIG>, after the electrode portion <NUM> is inserted into an entrance of a pulmonary vein <NUM> which is a target position, the inflation fluid is supplied into the balloon <NUM> via the second port <NUM> and the inflation lumen <NUM>. In this manner, the balloon <NUM> is inflated, and the electrode portion <NUM> pushed by the balloon <NUM> is expanded in the radial direction. At this time, the outer tube <NUM> moves to the distal side with respect to the inner tube <NUM>, and the proximal portion of the electrode portion <NUM> moves to the distal side. In this manner, the electrode portion <NUM> can deform while following the inflation of the balloon <NUM>. Therefore, the curved portion <NUM> located in a central portion of the electrode portion <NUM> is pushed against a biological wall <NUM> by the balloon <NUM>. The electrode portion <NUM> can deform to fit a shape of the biological tissue. Therefore, the electrode portion <NUM> can be brought into close contact with the biological tissue, and an electric signal is likely to be applied. In this state, the electric signal is applied from the power source unit <NUM> to the electrode portion <NUM> via the conductor <NUM>.

A pulsed electric signal is first applied from the power source unit <NUM> to a pair of electrode portions <NUM> and <NUM> adjacent to each other in the circumferential direction Z. In this manner, a current flows between the pair of electrode portions <NUM> and <NUM> adjacent to each other in the circumferential direction Z. Next, the pulsed electric signal is applied to the other pair of electrode portions <NUM> and <NUM> adjacent to each other in the circumferential direction Z. The electric signals are sequentially applied to all pairs of the electrode portions <NUM> and <NUM> adjacent to each other in the circumferential direction Z. An example of the applied electric signal will be described below. Electric field intensity applied by the power source unit <NUM> is <NUM>,<NUM> V/cm, and a pulse width of the electric signal is <NUM>µsec. The electric signals are repeatedly applied to all pairs of the electrode portions <NUM> adjacent to each other in the circumferential direction Z, <NUM> to <NUM> times in a cycle of once every <NUM> seconds, depending on a refractory period of a ventricular muscle. In this manner, cells in the entrance of the pulmonary vein are necrotized over the entire periphery. The electric signal may be applied between the plurality of electrode portions <NUM> that are not adjacent to each other, or the electric signal may be applied from the electrode portion <NUM> to a counter electrode attached to a body surface.

When the electric signal is completely applied, the balloon <NUM> is deflated. In this manner, the electrode portion <NUM> is contracted in the radial direction due to a self-restoring force. At this time, the outer tube <NUM> moves to the proximal side with respect to the inner tube <NUM>, and the proximal portion of the electrode portion <NUM> moves to the proximal side. In this manner, the electrode portion <NUM> can deform while following the deflation of the balloon <NUM>. Thereafter, all instruments inserted into the blood vessels are removed to complete the procedure. When the electrode portion <NUM> is formed of a material other than the superelastic alloy such as the Ni-Ti alloy, it is preferable to perform an operation for contracting the electrode portion <NUM> in the radial direction by pushing the inner tube <NUM> to the distal side (or by pulling the outer tube <NUM> to the proximal side).

As described above, the medical device <NUM> according to the first embodiment includes the elongated shaft portion <NUM>, the plurality of electrically independent electrode portions <NUM> disposed on the distal portion of the shaft portion <NUM>, extending along the length direction of the shaft portion <NUM>, and deformable in the radial direction of the shaft portion <NUM>, and the plurality of electrically independent conductors <NUM> including the buried portion <NUM> buried in the shaft portion <NUM>, and allowing the current to flow to the electrode portions <NUM>. At least one of the conductors <NUM> has the protruding portion <NUM> protruding from the distal surface <NUM> of the shaft portion <NUM>, and connected to the electrode portion <NUM>.

In the medical device <NUM> configured as described above, the buried portion <NUM> on the proximal side of the plurality of conductors <NUM> is buried in the shaft portion <NUM>. The protruding portion <NUM> on the distal side connected to the electrode portion <NUM> protrudes from the distal surface <NUM> of the shaft portion <NUM>. Therefore, the electrode portion <NUM> can be located inside the outer diameter of the shaft portion <NUM>. Accordingly, the electrode portion <NUM> does not protrude outward in the radial direction, and can have a reduced diameter. Therefore, the medical device <NUM> can be inserted into a narrow biological lumen, and a wide range can be effectively ablated by the electrode portion <NUM> curved in the radial direction. The electrode portion <NUM> may be located at a position the same as that of the outer peripheral surface of the shaft portion <NUM>. Furthermore, the conductor <NUM> is buried in the shaft portion <NUM>. Accordingly, bending rigidity of the shaft portion <NUM> is increased, and kink resistance is improved. For example, when the electrode portion <NUM> is brought into contact with the vicinity of the entrance of the pulmonary vein <NUM>, the shaft portion <NUM> cannot move in the radial direction in a puncture site of the atrial septum (for example, an oval fossa). Accordingly, the shaft portion <NUM> is curved. At this time, since the bending rigidity of the shaft portion <NUM> is increased, kink of the shaft portion <NUM> can be suppressed.

In addition, each of the plurality of conductors <NUM> has the protruding portion <NUM>, and each of the protruding portions <NUM> is connected to the different electrode portion <NUM>. In this manner, the independent electric signal can be applied to each of the plurality of electrode portions <NUM>.

In addition, the protruding portion <NUM> is connected to the electrode portion <NUM> located on the distal side of the protruding portion <NUM> in the axial direction. In this manner, the electrode portion <NUM> does not protrude outward in the radial direction, and the medical device <NUM> can easily have the reduced diameter.

In addition, at least a portion of the protruding portion <NUM> is perpendicular to the circumferential direction Z of the shaft portion <NUM>. In this manner, at least one of the electrode portion <NUM> and the protruding portion <NUM> can be accurately disposed at a suitable position in the circumferential direction Z of the shaft portion <NUM>.

In addition, at least a portion of the protruding portion <NUM> is parallel to the axis X of the shaft portion <NUM>, and at least a portion of the buried portion <NUM> has a spiral shape wound around the axis X of the shaft portion <NUM>. In this manner, the bending rigidity of the shaft portion <NUM> is not biased by a bending direction, and the shaft portion <NUM> having uniform quality can be formed.

In addition, the plurality of electrode portions <NUM> are equally disposed in the circumferential direction Z of the shaft portion <NUM>. In this manner, the electrode portion <NUM> can evenly ablate the target site.

In addition, when the radius from the axis X of the shaft portion <NUM> to the conductor <NUM> is defined as R, the number of the conductors <NUM> is defined as N, and the tilting angle of the conductor <NUM> with respect to the cross section orthogonal to the axis X of the shaft portion <NUM> is defined as θ, the distance D between central axes Y of the conductors <NUM> adjacent to each other is 2πR/N·sinθ. In this manner, the conductors <NUM> can be equally disposed in the circumferential direction Z of the shaft portion <NUM>. Therefore, when the electrode portions <NUM> are equally disposed in the circumferential direction Z, the electrode portions <NUM> are easily disposed so that the position of the conductor <NUM> is aligned with the electrode portion <NUM>.

In addition, the shaft portion <NUM> has the step portion <NUM> protruding to the distal side of the distal surface <NUM> from a position inside the distal surface <NUM> in the radial direction. In this manner, the protruding portion <NUM> of the conductor <NUM> can be supported by the step portion <NUM>, and disconnection of the conductor <NUM> can be suppressed. In the present embodiment, the outer tube <NUM> of the shaft portion <NUM> has the first outer tube <NUM> including the step portion <NUM>, and the second tube body <NUM> covering the outer peripheral surface of the first tube body <NUM> and fixed to the first tube body <NUM>. Accordingly, it is easy to form the step portion <NUM> from a position inside the distal surface <NUM> in the radial direction.

Also, the medical device <NUM> has the expansion body (for example, the balloon <NUM>) located between the shaft portion <NUM> and the electrode portion <NUM>, and inflatable outward in the radial direction of the shaft portion <NUM>. In this manner, the medical device <NUM> can bring the electrode portion <NUM> into close contact with the biological tissue by inflating the expansion body.

A medical device <NUM> according to a second embodiment is different from that according to the first embodiment only in the following point. As illustrated in <FIG>, the electrode portion <NUM> and the conductor <NUM> are provided to be biased in the circumferential direction Z of the shaft portion <NUM>.

The plurality of the conductors <NUM> have the protruding portion <NUM> protruding from the distal surface <NUM> of the shaft portion <NUM> in the distal direction at a position biased in the circumferential direction Z of the shaft portion <NUM>. Therefore, the plurality of conductors <NUM> inside the shaft portion <NUM> collectively form one group, and are disposed in a spiral shape while a gap <NUM> is interposed therebetween in a collective state. The protruding portion <NUM> and the electrode proximal portion <NUM> of the plurality of electrode portions <NUM> are located on the distal side of the plurality of the protruding portions <NUM>. Therefore, it is easy to electrically connect the electrode proximal portion <NUM> to the protruding portion <NUM>.

As described above, in the medical device <NUM> according to the second embodiment, the plurality of electrode portions <NUM> are disposed to be biased to a portion of the shaft portion <NUM> in the circumferential direction Z. In this manner, in the medical device <NUM>, only a specific site in the circumferential direction Z can be intentionally ablated by the electrode portion <NUM>. Therefore, in the medical device <NUM>, it is possible to easily adjust the electrode portion <NUM> so that only the specific site is ablated and other sites are not ablated. A biasing method of the protruding portion <NUM> is not particularly limited. Therefore, the protruding portion <NUM> and the electrode portion <NUM> may be provided to be biased at a plurality of locations in the circumferential direction Z of the shaft portion <NUM>. In addition, the distance between the adjacent protruding portions <NUM> and the distance between the adjacent electrode portions <NUM> may not be uniform.

A medical device <NUM> according to a third embodiment is different from that according to the first embodiment only in that the conductor <NUM> is braided, and has a support body <NUM> as illustrated in <FIG> and <FIG>.

A plurality of braided wire rods <NUM> are disposed inside the shaft portion <NUM>. A portion of the wire rods <NUM> is used as the conductor <NUM>. All of the wire rods <NUM> may be used as the conductors <NUM>. The wire rod <NUM> used as the conductor <NUM> is formed of a conductive material, and a surface thereof is coated with the insulation layer <NUM>. The wire rod <NUM> which is not used as the conductor <NUM> may be formed of the conductive material, or may not be formed of the conductive material. When the wire rod <NUM> which is not used as the conductor <NUM> is not formed of the conductive material, it is possible to suppress the electrical short-circuit with the wire rod <NUM> which is used as the conductor <NUM>. In the wire rod <NUM> which is not used as the conductor <NUM>, the surface may be coated with or may not be coated with the insulation layer <NUM>. The support body <NUM> that supports the electrode proximal portion <NUM> of the plurality of electrode portions <NUM> is fixed to an outer surface of the step portion <NUM> of the shaft portion <NUM>.

The support body <NUM> has a tubular shape, and a plurality of housing portions <NUM> that house the electrode proximal portions <NUM> of the electrode portions <NUM> are formed on the outer peripheral surface. The support body <NUM> is located away from the distal surface <NUM> in the distal direction. The support body <NUM> may not be located away from the distal surface <NUM> in the distal direction. The housing portion <NUM> is a groove extending in the length direction of the shaft portion <NUM>. The plurality of housing portions <NUM> are formed to be equally aligned in the circumferential direction Z of the support body <NUM>. Each of the housing portions <NUM> houses one of the electrode proximal portions <NUM>. The electrode proximal portion <NUM> is fixed to the support body <NUM> by using an adhesive in a state of being housed in the support body <NUM>. The support body <NUM> may house the protruding portion <NUM> of the conductor <NUM> instead of the electrode proximal portion <NUM>. Alternatively, the support body <NUM> may house both the electrode proximal portion <NUM> and the protruding portion <NUM>. In addition, the support body <NUM> may be provided on the outer peripheral surface of the inner tube <NUM> located on the distal side from the balloon <NUM> to house the electrode distal portion <NUM> located on the distal side of the electrode portion <NUM>.

As described above, the medical device <NUM> according to the third embodiment further has the annular support body <NUM> disposed on the outer peripheral surface of the shaft portion <NUM>, and the support body <NUM> has the housing portion <NUM> that houses at least one of the electrode portion <NUM> and the protruding portion <NUM>. In this manner, at least one of the electrode portion <NUM> and the protruding portion <NUM> can be accurately disposed at a suitable position in the circumferential direction Z of the shaft portion <NUM>.

In addition, the support body <NUM> is located away from the distal surface <NUM> in the distal direction. In this manner, the protruding portion <NUM> protruding from the distal surface <NUM> has a suitable posture in the gap between the support body <NUM> and the distal surface <NUM>, and is disposed at a suitable position of the support body <NUM>.

In addition, the conductor <NUM> is at least a portion of the plurality of wire rods <NUM> braided in a spiral shape, and the surface is covered with the insulation layer <NUM>. In this manner, the conductor <NUM> can use the braided wire rod <NUM>, and even when the conductors <NUM> come into contact with each other due to the braiding, the insulation layer <NUM> can suppress the electrical short-circuit.

The present invention is not limited to the above-described embodiments, and various modifications can be made by those skilled in the art within the scope of the present invention. For example, a configuration has been described in which the medical device <NUM> according to the above-described embodiments is used for treating the pulmonary vein. However, the medical device <NUM> may be used for treating other sites, for example, such as a renal artery, an ascending vena cava, and a ventricle.

In addition, the conductor <NUM> which transmits the current to the electrode portion <NUM> may not have a spiral shape, or may not be a portion of the braided wire rod <NUM>. For example, the conductor <NUM> may be the wire rod linearly extending along the axis X of the shaft portion <NUM>. In addition, the conductor <NUM> may be the wire rod that is curved or bent.

In addition, the expansion body of the medical device may not be the balloon <NUM>. In addition, the medical device may not have the expansion body that presses the electrode portion <NUM> outward in the radial direction. For example, the medical device can expand the electrode portion <NUM> in the radial direction of the shaft portion <NUM> by moving the outer tube <NUM> with respect to the inner tube <NUM> in the distal direction without being provided with the balloon <NUM>. In addition, when the electrode portion <NUM> or a portion of the conductor <NUM> is provided with an extendable portion, the outer tube <NUM> and the inner tube <NUM> may not be relatively movable in the axial direction. In this case, even when the balloon <NUM> is inflated and the electrode portion <NUM> is curved outward in the radial direction, the extendable portion extends. Accordingly, the outer tube <NUM> and the inner tube <NUM> do not need to relatively move. Alternatively, the fixing portion <NUM> may be slidable in the axial direction with respect to the outer peripheral surface of the inner tube <NUM>. In addition, the conductor may be buried in the inner tube <NUM> instead of the outer tube <NUM>. In this case, the conductor is electrically connected to the distal portion of the electrode portion <NUM>.

Claim 1:
A medical device (<NUM>, <NUM>, <NUM>) comprising:
an elongated shaft portion (<NUM>);
a plurality of electrically independent electrode portions (<NUM>) disposed on a distal side of the shaft portion (<NUM>), extending along a length direction of the shaft portion (<NUM>), and deformable in a radial direction of the shaft portion (<NUM>); and
a plurality of electrically independent conductors (<NUM>) including a buried portion (<NUM>) buried in the shaft portion (<NUM>), and allowing a current to flow to the electrode portions (<NUM>),
characterised in that
each of the plurality of conductors (<NUM>) has a protruding portion (<NUM>) protruding from a distal surface (<NUM>) of the shaft portion (<NUM>) and connected to the electrode portion (<NUM>) and each of the protruding portions (<NUM>) is connected to each of the electrode portions (<NUM>) different from each other,
wherein
each of the protruding portions (<NUM>) is parallel to an axis (X) of the shaft portion (<NUM>), and at least a portion of the buried portion (<NUM>) has a spiral shape wound around the axis of the shaft portion.