Patent ID: 12213729

DETAILED DESCRIPTION OF EMBODIMENTS

A. First Embodiment

<Background>

Completion of CART (controlled antegrade and retrograde tracking) technique devised by Kato in 2004 established a chronic total occlusion-percutaneous coronary intervention (hereinafter referred to as CTO-PCI) procedure by a retrograde approach. The establishment of the CTO-PCI procedure based on the CART technique enables certain levels of skilled medical doctors to canalize the CTO. An antegrade approach is, however, to be selected in the case that fails to detect retrograde-approachable collateral circulation.

According to the degree of calcification of CTO and anatomical conditions including the configuration of CTO such as length, bent and fragment geometry of CTO, a false lumen may be readily formed by a guide wire to cause a failure or a complication.

The parallel wire technique is effective in the antegrade approach in these cases. The parallel wire technique enables a true lumen to be retracked even in the case of aberrance of the guide wire into an inner membrane to form a false lumen and accordingly allows for canalization of CTO with the higher probability.

In some cases, however, even the parallel wire technique may cause expansion of the false lumen or formation of hematoma. As a result, this is likely to cause exclusion and collapse of the true lumen. There is accordingly a difficulty in tracking the true lumen.

In these cases, manipulation of the guide wire under IVUS (intravascular ultrasound) guide has been performed especially in Japan. IVUS is an intravascular imaging tool that obtains images of vascular lumen and inside of vascular wall with a relatively high resolution in real time.

In PCI, IVUS has been used for diagnosis. Using IVUS for treatment as a guide for manipulation of the guide wire (IVUS guide) allows for successful treatment in the case that is likely to fail without application of the IVUS guide. No exclusive devices have, however, been developed for this IVUS guide-based procedure. Under existing circumstances, IVUS is separately provided intravascularly from a device for treatment. Position information of each device and each blood vessel identified in an image obtained by IVUS indicates a relative positional relationship to an IVUS catheter. There is accordingly a need to three-dimensionally adapt IVUS information in the brain of the operator, based on position information of each vascular site and vascular bifurcation identified in an X-ray image and the relative positional relationship of the IVUS catheter and the guide wire. Even in an attempt for introduction of the guide wire to an optimal position by IVUS guide and for penetration of the guide wire for the purpose of CTO canalization, the IVUS catheter does not improve the operability of the guide wire in the false lumen. In some cases, the guide wire is likely to slip in or under an inner membrane and expand a false lumen, due to the limited penetration performance of the guide wire conventionally used for CTO. The IVUS guide is a technique that requires a highly sophisticated device manipulation technique and three-dimensional reconstruction of vascular information and has a problem of high dependency on the operator's skill.

By taking into account the above problems, the inventors have proposed an IVUS guide-based plasma guide wire CTO system that allows for canalization of CTO by CTO ablation (excision) using plasma. In this system, a plasma guide wire equipped with a distal-end tip serving as an electrode used for ablation and an IVUS imaging sensor configured to obtain images of vascular lumen and occlusion plaque of CTO are located on an identical device (plasma catheter).

This system enables the state of CTO and the position of the plasma guide wire to be recognized in real time by only a two-dimensional image of the IVUS imaging sensor. There is accordingly no need for separate intravascular manipulation of a plurality of devices and three-dimensional reconstruction of the IVUS-based image and the X-ray image information.

Unlike a conventional device that performs penetration using an ordinary guide wire, this system performs ablation by using the plasma guide wire in combination with the imaging sensor. This allows for reliable penetration of biological tissue around the electrode and ensures canalization of CTP. This system performs heartbeat synchronization and establishes electrical continuity with RF (radio-frequency) having a high voltage and an ultrashort pulse width between a distal end of the plasma guide wire and an electrode placed on a shaft distal side of the plasma catheter for generation of plasma.

The plasma catheter has a torque performance of transmitting a torque on a proximal end side toward a distal end side and is controllable to rotate to ±90 degrees. A distal-end outlet port of the plasma catheter (distal-end outlet port of the lumen in which the plasma guide wire is inserted) is located in a fixed direction (in the same direction as that of the guide wire for delivery) on the IVUS image. This configuration enables the catheter to be controlled by moving in a longitudinal direction and rotating with referring to the IVUS image, such that a target site to be penetrated is located at a center of the IVUS image (at an optimum angle). This eliminates the need for the three-dimensional reconstruction described above. A controllable stabilizer for catheter fixation is mounted to a distal end portion of the plasma catheter. This configuration enables the plasma catheter to be stably fixed in the optimum site described above with obtaining the IVUS image. Fixation of the plasma catheter to the lumen significantly improves the operability of the plasma guide wire in the false lumen or inside of CTO. When the stabilizer is formed from a radiopaque material, the position and the rotating direction of the plasma catheter are readily recognizable in radioscopy. This allows for manipulation of the plasma guide wire in radioscopy with referring to the IVUS image. Simultaneously, moving of the imaging sensor is controllable in the fixed plasma catheter, so that an image obtaining portion is movable. This configuration enables the distal end portion of the plasma guide wire to be traced on the IVUS image with fixation of the catheter. This accordingly allows for manipulation of the guide wire and penetration of the guide wire into a true lumen by ablation only with the IVUS image information without requiring radioscopy.

This type of complex device generally has a large profile and accordingly has difficulty in application to the CTO blood vessel. The plasma catheter of this disclosure, however, employs a common lumen for the guide wire for delivery and the lumen for imaging sensor and has a distal-end profile that is equivalent to that of the conventional IVUS catheter to be readily inserted into the coronary artery and into the CTO.

Even in a case that requires a shift to the retrograde approach for canalization, this system enables stable treatment by only the antegrade approach.

Additionally, this system shortens the manipulation time and allows for manipulation based on only the IVUS guide. This reduces X-ray exposure of the operator and the patient. Such wire manipulation under the IVUS guide is expected to have a significant saving effect of a contrast agent.

Accordingly, this system reduces the contingency of CTO canalization of the conventional CTO guide wires and devices and the recent CTO technique and improves the convenience of the IVUS guide. This is expected to spread the IVUS guide-based procedure in CTO-PCI and thereby contribute to shortening the manipulation time, reducing the radiation exposure and improving the success rate.

Embodiment

FIG.1is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system. The plasma guide wire CTO system is mainly used for treatment of CTO by an antegrade approach.

InFIG.1, the plasma guide wire CTO system1is comprised of a plasma catheter100, an imaging sensor200, an imaging console300, a plasma guide wire400and an RF generator500.FIG.1illustrates a schematic side view of the plasma catheter100.

FIG.2Ais a schematic side view illustrating a distal end portion of the plasma catheter100.

FIG.2Bis a schematic bottom view illustrating the distal end portion of the plasma catheter and illustrates a closed state of a stabilizer111comprised of a first stabilizer piece111aand a second stabilizer piece111bdescribed later.

FIG.2Cis a schematic bottom view illustrating the distal end portion of the plasma catheter100and illustrates an expanded and open state of the stabilizer111.

FIG.2Dis a diagram illustrating a method of integrally forming a first ring109, a second ring110, the first stabilizer piece111aand the second stabilizer piece111bdescribed later.

FIG.2Eis a diagram illustrating a method of integrally forming a first wire piece111cand a second wire piece111dfor opening and closing the stabilizer111, along with the first ring109, the second ring110, the first stabilizer piece111aand the second stabilizer piece111bdescribed later.

FIG.2Fis a diagram illustrating a method of integrally forming a first wire piece120and a second wire piece121for opening and closing the stabilizer111, along with the first ring109, the second ring110, the first stabilizer piece111aand the second stabilizer piece111bdescribed later.

FIG.3is a schematic diagram illustrating a section of the plasma catheter100, taken on a line A-A inFIG.1.

FIG.4is a schematic diagram illustrating the imaging sensor200.

FIG.5is a schematic diagram illustrating the plasma guide wire400.

FIGS.6A to6Dare diagrams illustrating one example of use of the plasma guide wire CTO system1in the case where CTO formed in coronary artery is canalized by an antegrade approach.

FIGS.1to6Dinclude illustrations of some parts of respective components at relative size ratios different from the actual conditions for convenience of explanation.FIGS.1to6Dalso include exaggerated illustrations of some parts of the respective components.

InFIG.1toFIG.6D(exceptFIG.3), a left side is called a “distal end side” of each component, and a right side is called a “proximal end side” of each component. With regard to each component, an end located on the distal end side is called “distal end”, and an end located on the proximal end side is called “proximal end”. A portion located at the distal end and in the vicinity of the distal end is called “distal end portion”, and a portion located at the proximal end and in the vicinity of the proximal end is called “proximal end portion”.

The plasma catheter100includes a hollow outer shaft101, a hollow first inner shaft102, a hollow second inner shaft103and a hollow distal-end tip104continuous with the first inner shaft102. The outer shaft101, the first inner shaft102and the second inner shaft103are long and have approximately circular cross sections. The distal-end tip104is tapered to gradually decrease its outer diameter toward its distal end and has an approximately circular cross section.

A first electrode106and a second electrode107are respectively mounted on an outer circumferential surface of the distal end portion and on an outer circumferential surface of the proximal end portion of the outer shaft101. The second electrode107is connected with a terminal502of the RF generator500described later via a cable40, a cable connector21and a cable20. The first electrode106and the second electrode107are made of metal materials having electrical conductivity.

The first electrode106made of, for example, an alloy including a radiopaque material such as gold, platinum or tungsten serves as a radiopaque marker in a body cavity.

Braids108(shown inFIG.3) serving as reinforcing members formed by knitting and braiding element wires are embedded inside of an outer circumferential surface of the outer shaft101. The element wire forming the braid108is made of a metal material having electrical conductivity and may be made of, for example, stainless steel such as SUS 304, a nickel titanium alloy or an alloy including a radiopaque material such as gold, platinum or tungsten. The element wire forming the braid108may be made of a known metal material having electrical conductivity other than these examples. The braids108are connected with the first electrode106and the second electrode107to establish electrical continuity with the first electrode106and the second electrode107. Accordingly, the second electrode107, the braids108and the first electrode106form one electrical conductor.

Hollow coil bodies (not shown) formed by winding element wires may be embedded inside of the outer circumferential surface of the outer shaft101, in place of the braids108. Like the braids108, the element wire forming the hollow coil body is made of a metal material having electrical conductivity and may be made of, for example, stainless steel such as SUS 304, a nickel titanium alloy or an alloy including a radiopaque material such as gold, platinum or tungsten. The wire forming the hollow coil body may be made of a known metal material having electrical conductivity other than these examples.

Referring toFIG.3, the first inner shaft102and the second inner shaft103are inserted into an outer lumen113of the outer shaft101. A hollow first wire shaft117aand a hollow second wire shaft117bare also inserted into the outer lumen113. The first inner shaft102, the second inner shaft103, the first wire shaft117aand the second wire shaft117bare extended to be approximately parallel to each other along a longitudinal direction of the outer shaft101.

Inside of the outer lumen113of the outer shaft101is sealed by a sealing member114. The sealing member114is placed between an inner circumferential surface of the outer shaft101and an outer circumferential surface of the first inner shaft102, an outer circumferential surface of the second inner shaft103, an outer circumferential surface of the first wire shaft117aand an outer circumferential surface of the second wire shaft117b.

The imaging sensor200(not shown inFIG.3) is inserted into a first inner lumen115of the first inner shaft102. The plasma guide wire400and an ordinary guide wire for delivery (delivery guide wire70described later) (not shown inFIG.3) are inserted into a second inner lumen116of the second inner shaft103. A first wire112aand a second wire112bdescribed later are respectively inserted into a first wire lumen118aof the first wire shaft117aand into a second wire lumen118bof the second wire shaft117b. The first wire112aand the second wire112bare respectively joined with the first wire piece111cand the second wire piece111ddescribed later and are inserted into the first wire lumen118aand into the second wire lumen118b.

Referring toFIG.1, an adjuster105is mounted on the proximal end of the outer shaft101and serves to open and close the stabilizer111described later and to move the imaging sensor200forward and backward in the first inner lumen115.

The first inner shaft102and the second inner shaft103protrude from the distal end of the outer shaft101. A protruded part of the second inner shaft103from the distal end of the outer shaft101is configured to be shorter than a protruded part of the first inner shaft102from the distal end of the outer shaft101.

A distal end of the second inner shaft103is inclined toward the first inner shaft102. An opening103ais provided on the distal end of the second inner shaft103to communicate with the second inner lumen116of the second inner shaft103(shown inFIG.3).

An opening102ais provided on the outer circumferential surface of the first inner shaft102at a position between the distal end of the outer shaft101and a distal end of the first inner shaft102to communicate with the first inner lumen115of the first inner shaft102(shown inFIG.3). The opening102ais located on the distal end side to a maximum extent, such as to enable the delivery guide wire70to be visualized by the imaging sensor200in the process of inserting the plasma catheter100into a target site and positioning the plasma catheter100. The opening102ais provided on the same side as the second inner shaft103and the opening103aand on extensions of the second inner shaft103and the opening103ain a radial direction of the first inner shaft102.

The distal-end tip104is joined with the distal end of the first inner shaft102. An opening104ais provided at a distal end of the distal-end tip104. The opening104ais arranged to communicate with an inner lumen (not shown) of the distal-end tip104and with the first inner lumen115of the first inner shaft102.

In the inner lumen of the distal-end tip104and the first inner lumen115of the first inner shaft102, a proximal end of the delivery guide wire70(shown inFIG.6A) goes into the plasma catheter100through the opening104a, goes out of the plasma catheter100through the opening102a, goes into the second inner lumen116of the second inner shaft103through the opening103a, goes through the second inner lumen116and goes out of the plasma catheter100through the proximal end of the second inner shaft103.

A third opening (not shown) may be provided on the proximal end side of the opening103aon the outer circumferential surface of the outer shaft101to pass through the second inner shaft103and communicate with the second inner lumen116. In this case, the proximal end of the delivery guide wire70may be arranged to go out of the plasma catheter100through the third opening.

Instead of the opening102a, another opening (not shown) may be provided on the outer circumferential surface of the first inner shaft102. More specifically, another opening may be provided at a position opposed to the opening102a, i.e., on the opposite side to the second inner shaft103, in the radial direction of the first inner shaft102. In this case, the proximal end of the delivery guide wire70may be arranged to enter from the opening104a, to go through the inner lumen of the distal-end tip104and the first inner lumen115of the first inner shaft102and to go out from another opening.

Each of the outer shaft101, the first wire shaft117a, the second wire shaft117b, the sealing member114, the first inner shaft102, the second inner shaft103and the distal-end tip104is made of a resin having insulation properties and may be made of, for example, a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, a polyester such as polyethylene terephthalate, a thermoplastic resin such as polyvinyl chloride, ethylene-vinyl acetate copolymer, crosslinked ethylene-vinyl acetate copolymer or polyurethane, polyamide elastomer, polyolefin elastomer, polyurethane elastomer, silicone rubber, or latex rubber. Each of the outer shaft101, the first wire shaft117a, the second wire shaft117b, the sealing member114, the first inner shaft102, the second inner shaft103and the distal-end tip104may be made of a known material other than these examples.

A transducer201and a driving cable202of the imaging sensor200described later are placed in the protruded part of the first inner shaft102from the distal end of the outer shaft101or more specifically in a part of the first inner lumen115located between the distal end of the first inner shaft102and the distal end of the outer shaft101. The transducer201serves to transmit ultrasonic waves to biological tissue via the first inner shaft102and receive reflected sound of the ultrasonic waves. The imaging console300obtains an image of the biological tissue, based on a difference between the transmitted sound and the received sound by the transducer201. It is accordingly preferable that the part located between the distal end of the first inner shaft102and the distal end of the outer shaft101is formed from a resin having a difference of an acoustic impedance from that of the biological tissue, for example, polyethylene.

The distal-end tip104is placed on the distal end of the plasma catheter and is preferably made of a resin having the higher flexibility than those of the outer shaft101, the first inner shaft102and the second inner shaft103, for example, polyurethane elastomer, in order not to damage the biological tissue in the body cavity.

Any method may be employed to join the distal-end tip104with the first inner shaft102. For example, a method using an insulating adhesive such as an epoxy-based adhesive may be employed for joining.

The first ring109and the second ring110are mounted on the outer circumferential surface of the first inner shaft102. The first ring109is joined with the distal end of the first inner shaft102. The first ring109may be joined with a proximal end of the distal-end tip104or may be joined with both the distal end of the first inner shaft102and the proximal end of the distal-end tip104.

Any method may be employed to join the first ring109with the distal end of the first inner shaft102, to join the first ring109with the proximal end of the distal-end tip104, or to join the first ring109with the distal end of the first inner shaft102and with the proximal end of the distal-end tip104. For example, a method using an insulating adhesive such as an epoxy-based adhesive may be employed for joining.

The first ring109may be placed on the proximal end side of the distal end of the first inner shaft102.

The second ring110is placed on the proximal end side of the first ring109to be away from the first ring109and is mounted to be slidably movable along the longitudinal direction of the first inner shaft102on the outer circumferential surface of the first inner shaft102. The stabilizer111comprised of the first stabilizer piece111aand the second stabilizer piece111bis mounted between the first ring109and the second ring110(the second stabilizer piece111bis not shown inFIG.1).

As described above,FIG.2Ais a schematic side view illustrating the distal end portion of the plasma catheter100, andFIG.2BandFIG.2Care schematic bottom views illustrating the distal end portion of the plasma catheter100.FIG.2Billustrates the stabilizer111in the closed state.FIG.2Cillustrates the stabilizer111in the open state.

A distal end and a proximal end of the first stabilizer piece111aare respectively joined with the first ring109and with the second ring110. Similarly, a distal end and a proximal end of the second stabilizer piece111bare respectively joined with the first ring109and with the second ring110.

The first stabilizer piece111aand the second stabilizer piece111bare located at positions opposed to each other in the radial direction of the first inner shaft102. More specifically, the first stabilizer piece111aand the second stabilizer piece111bare arranged to be placed on an identical virtual plane α as shown inFIG.2BandFIG.2C.

InFIG.2A, on the other hand, the first inner shaft102and the second inner shaft103are arranged such that a longitudinal axis of the first inner shaft102and a longitudinal axis of the second inner shaft103are placed on an identical virtual plane β.

It is preferable that the first stabilizer piece111aand the second stabilizer piece111bare arranged, such that the virtual plane α and the virtual plane β are approximately orthogonal to each other.

Referring toFIG.2B, in the closed state, the first stabilizer piece111aand the second stabilizer piece111bare extended in a longitudinal axis direction of the first inner shaft102between the first ring109and the second ring110to be approximately parallel to the first inner shaft102. The second ring110is placed at a position on the proximal end side to a maximum extent, i.e., at a position closer to the opening103a.

Referring toFIG.2C, the second ring110is moved toward the distal end of the first inner shaft102, so that the first stabilizer piece111aand the second stabilizer piece111bare expanded outward in the radial direction of the first inner shaft102to be in the open state.

The second ring110is placed to be located on the proximal end side of the opening102a, in both the open state and the closed state of the stabilizer111.

The first stabilizer piece111aand the second stabilizer piece111bmay be formed in rectangular cross sectional shapes. In order to minimize the damage of the blood vessel by expansion of the stabilizer, forming the rectangular cross sectional shape reduces the pressure in a direction of expansion of the stabilizer111and causes a maximum stress to be applied for catheter fixation in a longitudinal side direction of the cross section.

In order to control the configuration of the stabilizer111during expansion, a groove or a cut may be provided in an outer circumferential surface of the first stabilizer piece111ato be approximately perpendicular to a longitudinal axis direction of the first stabilizer piece111a. Similarly, a groove or a cut may be provided in an outer circumferential surface of the second stabilizer piece111bto be approximately perpendicular to a longitudinal axis direction of the second stabilizer piece111b. Providing such grooves or cuts in the outer circumferential surfaces of the first stabilizer piece111aand the second stabilizer piece111bmay cause the stabilizer111to have, for example, a hexagonal shape in bottom view during expansion of the stabilizer111(as shown inFIG.2C). More specifically, in the bottom view, each of the first stabilizer piece111aand the second stabilizer piece111bmay be formed in a trapezoidal shape (as shown inFIG.2C).

Each of the stabilizer111, the first ring109and the second ring110is made of a metal material or a resin material. The metal material may be, for example, stainless steel such as SUS 304, a nickel titanium alloy or an alloy including a radiopaque material such as gold, platinum or tungsten. The resin material may be, for example, a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, a polyester such as polyethylene terephthalate, a thermoplastic resin such as polyvinyl chloride, ethylene-vinyl acetate copolymer, crosslinked ethylene-vinyl acetate copolymer or polyurethane, polyamide elastomer, polyolefin elastomer, polyurethane elastomer, silicone rubber, or latex rubber. Each of the stabilizer111, the first ring109and the second ring110may be made of a known metal material or a known resin material other than these examples.

When the stabilizer111is made of a nickel titanium alloy having shape-memory effect, it is preferable that the closed state of the stabilizer111is stored in advance in the nickel titanium alloy. This enables the stabilizer111to be relatively readily shifted from the open state to the closed state.

Any method may be employed to join the stabilizer111with the first ring109and the second ring110. When the stabilizer111, the first ring109and the second ring110are made of resins, when the stabilizer111is made of a metal material and the first ring109and the second ring110are made of resin materials, or when the stabilizer111is made of a resin material and the first ring109and the second ring110are made of metal materials, for example, a method using an adhesive such as an epoxy-based adhesive may be employed for joining. When the stabilizer111, the first ring109and the second ring110are made of metal materials, a laser welding technique or a brazing technique using silver solder, gold solder, zinc or metal solder such as Sn—Ag alloy or Au—Sn alloy may be employed for joining.

Referring toFIGS.2A to2C, the first wire112aand the second wire112bare joined with the second ring110(only the first wire112ais illustrated inFIG.2A). More specifically, the first wire piece111cdescribed later is provided on the proximal end of the second ring110(as shown inFIG.2E). The first wire112ais placed to overlap with and to be joined with this first wire piece111c(shown inFIG.2EandFIG.3) along the longitudinal axis direction of the first inner shaft102. Similarly, the second wire piece111ddescribed later is provided on the proximal end of the second ring110(as shown inFIG.2E). The second wire112bis placed to overlap with and to be joined with this second wire piece111d(shown inFIG.2EandFIG.3) along the longitudinal axis direction of the first inner shaft102. The first wire piece111cand the second wire piece111drespectively pass through the first wire lumen118aand the second wire lumen118bdescribed later to be extended to the middle of the outer shaft101. The first wire112aand the second wire112bare respectively extended along outer circumferential surfaces of middle parts of the first inner shaft102and the second inner shaft103from a proximal end of the second ring110toward proximal ends of the first inner shaft102and the second inner shaft103in the longitudinal axis directions of the first inner shaft102and the second inner shaft103.

The first wire112ais configured to be longer than the first wire piece111c, but the first wire112aand the first wire piece111cmay have identical lengths. Similarly, the second wire112bis configured to be longer than the second wire piece111d, but the second wire112band the second wire piece111dmay have identical lengths.

Each of the first wire piece111cand the second wire piece111dis formed from a thin plate member having an approximately rectangular or circular arc-shaped cross section.

The first wire112aand the second wire112bare formed from round element wires of an approximately circular cross section. The first wire112ais formed such that the outer diameter of a part that overlaps with the first wire piece111cis smaller than the outer diameter of a part that does not overlap with the first wire piece111c. Similarly, the second wire112bis formed such that the outer diameter of a part that overlaps with the second wire piece111dis smaller than the outer diameter of a part that does not overlap with the second wire piece111d.

Referring toFIG.2A, the first wire112aand the first wire piece111care arranged to be approximately parallel to the first stabilizer piece111ain the closed state. The first wire112aand the first wire111care placed to be shifted to the second inner shaft103-side relative to the first stabilizer piece111ain a circumferential direction of the second ring110(in other words, in a circumferential direction of the first inner shaft102). Similarly, the second wire112band the second wire piece111dare arranged to be approximately parallel to the second stabilizer piece111bin the closed state (not shown inFIG.2A). The second wire112band the second wire piece111dare placed on the second inner shaft103-side relative to the second stabilizer piece111b(not shown inFIG.2A) in the circumferential direction of the second ring110(in other words, in the circumferential direction of the first inner shaft102).

Referring toFIG.3, the first wire112aand the second wire112brespectively pass through the first wire lumen118aand the second wire lumen118bof the outer shaft101and are connected with a first dial105aof the adjuster105(shown inFIG.1). Operation of the first dial105amoves the second ring110on the outer circumferential surface of the first inner shaft102via the first wire112aand the second wire112bin a distal end direction of the first inner shaft102, so as to expand the stabilizer111. Simultaneously, the degree of expansion is adjustable to expand the stabilizer111to an optimum size, with using the imaging console described later to observe an image of biological tissue based on an ultrasonic signal from the imaging sensor200described later. This configuration minimizes the damage of the blood vessel. In the expanded state of the stabilizer111, another operation of the first dial105auses the shape-memory effect of nickel titanium alloy to move the second ring110on the outer circumferential surface of the first inner shaft102via the first wire112aand the second wire112btoward the proximal end of the first inner shaft102. This returns the stabilizer111to the closed state.

Each of the first wire112aand the second wire112bis made of a metal material or a resin material. The metal material may be, for example, chromium molybdenum steel, nickel chromium molybdenum steel, stainless steel such as SUS 304 or a nickel titanium alloy. The resin material may be, for example, super engineering plastic such as polyether ether ketone, polyether imide, polyamide imide, polysulfone, polyimide or polyether sulfone. Each of the first wire112aand the second wire112bmay be made of a known metal material or a known resin material other than these examples.

The stabilizer111, the first ring109and the second ring110may be formed as separate bodies or may be formed integrally. In the case of integral formation, as shown inFIG.2D, the first ring109, the second ring110, the first stabilizer piece111aand the second stabilizer piece111bare formed by hollowing out a side wall of a cylindrical hollow pipe60that is made of a resin material or a metal material. In the case ofFIG.2D, the first wire112aand the second wire112bare directly joined with the second ring. In this case, any method may be employed to join the first wire112aand the second wire112bwith the second ring110. When the first wire112a, the second wire112band the second ring110are made of resins, when the first wire112aand the second wire112bare made of metal materials and the second ring110is made of a resin material, or when the first wire112aand the second wire112bare made of resin materials and the second ring110is made of a metal material, for example, a method using an adhesive such as an epoxy-based adhesive may be employed for joining. When the first wire112a, the second wire112band the second ring110are made of metal materials, a laser welding technique or a brazing technique using silver solder, gold solder, zinc or metal solder such as Sn—Ag alloy or Au—Sn alloy may be employed for joining.

As shown inFIG.2E, when the stabilizer111, the first ring109and the second ring110are formed integrally, the first wire piece111cand the second wire piece111d, in addition to the first ring109, the second ring110, the first stabilizer piece111aand the second stabilizer piece111bare formed by hollowing out a side wall of a cylindrical hollow pipe60that is made of a resin material or a metal material. The first wire piece111cis arranged to be approximately parallel to the first stabilizer piece111ain the closed state and is formed at a position shifted from the first stabilizer piece111ato the second inner shaft103-side (shown inFIG.2A) in a circumferential direction of the second ring110. Similarly, the second wire piece111dis arranged to be approximately parallel to the second stabilizer piece111bin the closed state and is formed at a position shifted from the second stabilizer piece111bto the second inner shaft103-side in the circumferential direction of the second ring110.

In this case, the first wire112aand the first wire piece111cmay be arranged to overlap with each other in the longitudinal axis direction of the first inner shaft102and to be joined with each other as described above. Similarly, the second wire112band the second wire piece111dmay be arranged to overlap with each other in the longitudinal axis direction of the first inner shaft102and to be joined with each other. The configuration shown inFIG.2Eis illustrated in the plasma catheter100inFIG.1toFIG.2C,FIG.3andFIG.6AtoFIG.6D.

As shown inFIG.2F, when the stabilizer111, the first ring109and the second ring110are formed integrally, the first wire piece120and the second wire piece121, in addition to the first ring109, the second ring110, the first stabilizer piece111aand the second stabilizer piece111bare formed by hollowing out a side wall of a cylindrical hollow pipe60that is made of a resin material or a metal material.

The first wire piece120is comprised of a first curved portion120aand a first linear portion120bthat is continuous with the first curved portion120a. The first curved portion120ais curved toward the second inner shaft103(shown inFIG.2A), and the first linear portion120bis extended to be approximately parallel to the first stabilizer piece111ain the closed state.

The second wire piece121is comprised of a second curved portion121aand a second linear portion121bthat is continuous with the second curved portion121a. The second curved portion121ais curved toward the second inner shaft103(shown inFIG.2A), and the second linear portion121bis extended to be approximately parallel to the second stabilizer piece111bin the closed state. The first curved portion120aand the second curved portion121amay be formed linearly.

In this case, the first wire112aand the first linear portion120bof the first wire piece120may be arranged to overlap with each other in the longitudinal axis direction of the first inner shaft102and to be joined with each other. Similarly, the second wire112band the second linear portion121bof the second wire piece121may be arranged to overlap with each other in the longitudinal axis direction of the first inner shaft102and to be joined with each other.

Any method may be employed to join the first wire112awith the first wire piece111cor with the first linear portion120bof the first wire piece120. When the first wire112a, the first wire piece111cand the first wire piece120are made of resins, when the first wire112ais made of a metal material and the first wire piece111cand the first wire piece120are made of resin materials, or when the first wire112ais made of a resin material and the first wire piece111cand the first wire piece120are made of metal materials, for example, a method using an adhesive such as an epoxy-based adhesive may be employed for joining. When the first wire112a, the first wire piece111cand the first wire piece120are made of metal materials, a laser welding technique or a brazing technique using silver solder, gold solder, zinc or metal solder such as Sn—Ag alloy or Au—Sn alloy may be employed for joining. The same applies to joining of the second wire112bwith the second wire piece111dor with the second linear portion121bof the second wire piece121.

Referring toFIG.3, the first wire112ajoined with the first wire piece111c(shown inFIG.2E) formed by hollowing out the side wall of the hollow pipe60is inserted into the first wire lumen118a. The second wire112bjoined with the second wire piece111d(shown inFIG.2E) formed by hollowing out the side wall of the hollow pipe60is inserted into the second wire lumen118b.

When the stabilizer111, the first ring109, the second ring110, the first wire piece120and the second wire piece121are formed integrally by the method shown inFIG.2F, the first linear portion120bof the first wire piece120is placed instead of the first wire piece111cand the second linear portion121bof the second wire piece121is placed instead of the second wire piece111din the cross section ofFIG.3.

FIG.1,FIG.2A,FIG.2BandFIG.2Cillustrate the configuration of expanding the stabilizer111by fixing the distal end of the stabilizer111and pressing the proximal end of the stabilizer111in a distal end direction. Another configuration may be employed to expand the stabilizer111by fixing the proximal end of the stabilizer111and pulling the distal end of the stabilizer111in a proximal end direction.

Referring toFIG.1andFIG.4, the imaging sensor200is a long medical device and is comprised of the transducer201configured to transmit and receive ultrasonic waves, the hollow driving cable202and a connector203. Electric wire (not shown) is connected with the transducer201and is connected with a cable50through an inner lumen of the hollow driving cable202and an inner lumen of the connector203. The cable50is connected with the imaging console300.

Operation of the imaging console300causes the transducer201placed on a distal end to transmit ultrasonic waves in a radial direction and to receive ultrasonic waves reflected from biological tissue, while rotating about a longitudinal axis thereof in a body cavity. The transducer201also serves to send the received ultrasonic waves through the electric wire and the cable50described above to the imaging console300. In the plasma guide wire CTO system1, the imaging sensor200is inserted in the first inner lumen115of the first inner shaft102to be used. The imaging sensor200is connected with a second dial105bof the adjuster105between a distal end and a proximal end thereof. Operation of the second dial105bcauses the transducer201placed on the distal end of the imaging sensor200to move back and forth along the longitudinal axis direction of the first inner shaft102.

The imaging console300controls rotation of the transducer201and transmission and reception of ultrasonic waves by the transducer201. The imaging console300also serves to convert an ultrasonic signal received from the transducer201into an image signal and display the image signal on a display302.

Referring toFIG.1andFIG.5, the plasma guide wire400includes a core shaft401, a hollow coil body402, a distal-end tip403and a covering layer404.

The core shaft401is made of a metal material having electrical conductivity and may be made of, for example, chromium molybdenum steel, nickel chromium molybdenum steel, stainless steel such as SUS 304 or a nickel titanium alloy. The core shaft401may be made of a known metal material other than these examples.

The coil body402is arranged to surround a distal end portion of the core shaft401and is formed in a cylindrical shape by spirally winding element wires. The element wire forming the coil body402is made of a metal material having electrical conductivity and may be made of, for example, stainless steel such as SUS 304, a nickel titanium alloy or an alloy including a radiopaque material such as gold, platinum or tungsten. The element wire forming the coil body402may be made of a known metal material other than these examples.

The distal-end tip403is a member configured to join a distal end of the core shaft401with a distal end of the coil body402. The distal-end tip403is made of a metal material having electrical conductivity and may be made of, for example, chromium molybdenum steel, nickel chromium molybdenum steel, stainless steel such as SUS 304 or a nickel titanium alloy. The distal-end tip403is joined with the distal end of the core shaft401and the distal end of the coil body402by welding such as laser welding. The distal-end tip403may be formed by melting the distal end of the core shaft401. In other words, the distal-end tip403and the core shaft401may be formed integrally. The distal-end tip403has a cone-shaped tapered distal end. In other words, the distal end of the distal-end tip403is formed in an arrowhead shape. An apex of the distal-end tip403may not be sharp-pointed but may be rounded or flat.

A middle joint portion406is a member configured to join the core shaft401with a proximal end of the coil body402. The middle joint portion406is formed by brazing the core shaft401with the proximal end of the coil body402with a hard solder such as silver solder or gold solder. The middle joint portion406may be formed by welding, for example, laser welding, the core shaft401with the coil body402.

The covering layer404is formed to cover from a proximal end portion of the distal-end tip403across the coil body402to a proximal end portion of the core shaft401. The distal end of the distal-end tip403is exposed from a distal end of the covering layer404. A proximal end of the core shaft401is exposed from a proximal end of the covering layer404. The covering layer404is made of a resin having insulation properties and may be made of, for example, a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, a polyester such as polyethylene terephthalate, a thermoplastic resin such as polyvinyl chloride, ethylene-vinyl acetate copolymer, crosslinked ethylene-vinyl acetate copolymer or polyurethane, polyamide elastomer, polyolefin elastomer, polyurethane elastomer, silicone rubber, or latex rubber. The covering layer404may be made of super engineering plastic such as polyether ether ketone, polyether imide, polyamide imide, polysulfone, polyimide or polyether sulfone. The covering layer404may be made of a known material other than these examples.

A distal end joint portion405is a member configured to join the distal end of the covering layer404with the proximal end portion of the distal-end tip403and the distal end portion of the coil body402and has insulating properties and heat resistance. The distal end joint portion405may be formed, for example, from an adhesive such as an epoxy-based adhesive.

A proximal end joint portion407is a member configured to join the proximal end of the covering layer404with the proximal end portion of the core shaft401and has insulating properties. The proximal end joint portion407may be formed, for example, from an adhesive such as an epoxy-based adhesive.

It is preferable to form a bent first curve in a distal end portion of the plasma guide wire400(as shown inFIG.1), prior to the procedure.

The plasma guide wire400is inserted through the connector30into the second inner lumen116of the second inner shaft103and is placed in use such that the distal end portion thereof protrudes from the distal end of the second inner shaft103. The proximal end portion of the core shaft401of the plasma guide wire400is connected with a terminal501of the RF generator500described later via a cable connector11and a cable10.

The RF generator500outputs high frequency power between the terminal501and the terminal502. The terminal501is connected with the plasma guide wire400via the cable10and the cable connector11. The terminal502is connected with the second electrode107of the plasma catheter100via the cable20, the cable connector21and the cable40.

In the state in which the plasma catheter100is transported to CTO and the distal end portion of the plasma guide wire400protrudes from the distal end of the second inner shaft103, when high frequency power is output between the terminal501and the terminal502, streamer discharge occurs at the distal-end tip403, due to a voltage difference between the first electrode106of the plasma catheter100and the distal-end tip403of the plasma guide wire400. Ablation of CTO is performed by this streamer discharge.

FIGS.6A to6Dare diagrams illustrating one example of use of the plasma guide wire CTO system1in the case where CTO formed in coronary artery is canalized by an antegrade approach.FIGS.6A to6Dillustrate a coronary artery80, a CTO81occurring in the coronary artery80, a false lumen82formed in or under inner membrane of the coronary artery80, a fibrous film or plaque83(hereinafter simply referred to as fibrous film83) that is present between the coronary artery80and the false lumen82and a true lumen, and a true lumen84. The fibrous film83may be formed fibrously on the surface of a CTO lesion.

FIG.6Aillustrates the state in which the delivery guide wire70manipulated by the operator strays in the inner membrane of the coronary artery80and forms the falser lumen82in or under the inner membrane.

Referring toFIG.6B, the operator inserts the proximal end of the delivery guide wire70from the opening104aof the distal-end tip104of the plasma catheter100through the inner lumen of the distal-end tip104, the first inner lumen115of the first inner shaft102(shown inFIG.3), and the opening102aof the first inner shaft102into the second inner lumen116of the second inner shaft108. The operator then transports the plasma guide catheter100along the delivery guide wire70to the false lumen82and observes inside of the CTO lesion and inside of the false lumen with the imaging sensor200. At this moment, the operator transports the plasma catheter100in the state in which the transducer201of the imaging sensor200is located very close to the proximal end side of the opening102ain the first inner lumen115of the first inner shaft102. This aims to move the observation site of the imaging sensor200by moving the plasma catheter100. The operator checks an image of the coronary artery80from the transducer201on the display302and locates the plasma catheter100at an optimum position for penetration into the true lumen by the plasma guide wire400, while transporting the plasma catheter100.

After locating the plasma catheter100at the optimum position, the operator refers to the position of the delivery guide wire70on the display302and rotates the plasma catheter100such that a target true lumen is mutually opposed across the plasma catheter100and that the opening103aas the outlet of the plasma guide wire400is located on the true lumen side and is mutually opposed to the true lumen. Accordingly, the delivery guide wire70serves as a landmark of the outlet of the plasma guide wire400.

The operator operates the first dial105aof the adjuster105to move the second ring110in the distal end direction via the first wire112aand the second wire112band expand the stabilizer111(the expanded state of the stabilizer111is not illustrated inFIG.6B). The stabilizer111is expanded to press the biological tissue in the false lumen and thereby fix the plasma catheter100. While using the imaging sensor200to check the position and the degree of expansion of the stabilizer111, the operator expands the stabilizer111and fixes the plasma catheter100at an optimum position where the plasma catheter100is fixed without excessively expanding the false lumen.

Referring toFIG.6C, the operator uses the imaging sensor200to confirm successful fixation of the plasma catheter100and then removes the delivery guide wire70. After removal of the delivery guide wire70, the operator operates the second dial105bof the adjuster105to move the imaging sensor200back and forth along the longitudinal axis direction of the first inner shaft102and observe and determine a site optimum for penetration into the true lumen.

Referring toFIG.6D, after expanding the stabilizer111and fixing the plasma catheter100, the operator inserts the plasma guide wire400into the second inner lumen116of the second inner shaft103and causes the plasma guide wire400to protrude from the opening103aat the distal end, while checking the image of the coronary artery80from the transducer201on the display302. The operator then guides the distal end of the plasma guide wire400to the optimum site for penetration described above, while checking the image of the plasma guide wire400from the transducer201on the display302. A second curve may be formed on a distal end side or on a proximal end side of the first curve (shown inFIG.1) of the plasma guide wire400required for such guiding. The operator operates the RF generator500to output high frequency power between the first electrode106and the distal-end tip403of the plasma guide wire400via the terminal501and the terminal502. Streamer discharge accordingly occurs at the distal-end tip403of the plasma guide wire400. This performs ablation of the fibrous film83and causes the plasma guide wire400to reach the true lumen84.

The method shown inFIGS.6A to6Dachieves canalization of the CTO81by the plasma guide wire CTO system1.

<Modifications>

(1) In the above embodiment, the stabilizer piece111aand the stabilizer piece111bare formed from plate members (as shown inFIGS.2D to2F). The stabilizer piece111aand the stabilizer piece111bmay be formed from mesh members made of a metal material or a resin material, instead of the plate members.

(2) A modification of the above embodiment may be further provided with a balloon configured to cover the stabilizer111(shown inFIGS.2A to2F) (hereinafter referred to as balloon A) and with a hollow inflation shaft that is connected with the balloon A and that is inserted in the outer lumen113of the outer shaft101(hereinafter referred to as inflation shaft A).

In this modified configuration, a fluid including a radiopaque material may be injected into the balloon A through the inflation shaft A. This configuration enables opening and closing of the stabilizer to be checked in an X-ray image.

(3) In the above embodiment, the mechanism of opening and closing the stabilizer111(hereinafter referred to as stabilizer opening/closing mechanism) is comprised of the first ring109, the second ring110, the first stabilizer piece111a, the second stabilizer piece111b, the first wire112aand the second wire112b(as shown inFIG.2BandFIG.2C).

A modification may employ an expandable and contractible balloon (hereinafter referred to as balloon B), in place of the stabilizer111and may employ a balloon B expansion/contraction mechanism to expand and contract the balloon B, in place of the stabilizer opening/closing mechanism. The balloon B expansion/contraction mechanism is connected with the balloon B and is configured by a hollow inflation shaft B that is inserted into the outer lumen113of the outer shaft101. Injecting a fluid into the balloon B through the inflation shaft B expands the balloon B, whereas discharging the fluid from the balloon B contracts the balloon B. The balloon B preferably has a cross section in an elliptical shape.

(4) In the above embodiment, the imaging sensor200is inserted into the first inner lumen115of the first inner shaft102to obtain an image of intravascular biological tissue (as shown inFIGS.6A to6D). A modification may insert an OCT (optical coherence tomography) or a camera, in place of the imaging sensor200, to obtain an image of intravascular biological tissue. In the case of using the OCT or the camera, a physiological saline solution is injected into the first inner lumen115.

(5) In a modification of the above embodiment, the stabilizer111(shown inFIGS.2A to2F) may be formed from a member having a large difference of an acoustic impedance from that of the biological tissue. In another modification, the surface of the stabilizer111may be formed to have concavity and convexity, in order to facilitate reflection of ultrasonic waves from the transducer201of the imaging sensor200.

In these modifications, the stabilizer111may serve as an orientation marker to check the orientation and the direction of the plasma catheter100on an image obtained by the imaging sensor200. The stabilizer111may be in the open state or may be in the closed state when serving as the orientation marker.

(6) The above embodiment employs the stabilizer111comprised of the two stabilizer pieces (the first stabilizer piece111aand the second stabilizer piece111b) (as shown inFIGS.2A to2E).

A stabilizer comprised of three or more stabilizer pieces (hereinafter referred to as stabilizer A) may be employed in place of the stabilizer111. The three or more stabilizer pieces may be arranged as follows in a cross section of the stabilizer A (hereinafter referred to as cross section A). In the cross section A, two stabilizer pieces (hereinafter referred to as stabilizer piece a and stabilizer piece b) out of the three or more stabilizer pieces are arranged to be opposed to each other. The remaining stabilizer pieces are arranged only in one of two areas that are adjacent to each other across a virtual line connecting the stabilizer piece a with the stabilizer piece b (hereinafter referred to as virtual line L) as the boundary.

The stabilizer A including the three or more stabilizer pieces arranged as described above may serve as an orientation marker of the higher accuracy to check the orientation and the direction of the plasma catheter100on an image obtained by the imaging sensor200. In this application, it is preferable that the opening103aof the second inner shaft103(shown inFIG.1) is placed in one area or in the other area out of the two areas adjacent to each other across the virtual line L as the boundary in the cross section A.

(7) In the above embodiment, the stabilizer opening/closing mechanism (described above in Modification (3)) employs the configuration of moving the second ring110in the distal end direction by means of the first wire112aand the second wire112bto expand the stabilizer111(as shown inFIG.2BandFIG.2C).

A modification may be configured to move the second ring110in the distal end direction by utilizing a fluid-based pressing force, in place of the first wire112aand the second wire112b. For example, a balloon (hereinafter referred to as balloon C) may be mounted to the first inner shaft102, and the proximal end of the second ring110may be mounted to a distal end of the balloon C.

In this modified configuration, injection of a fluid into the balloon C expands the balloon C and moves the second ring110in the distal end direction of the first inner shaft102by using a force of expanding the balloon C in the longitudinal axis direction of the first inner shaft102, so as to expand the stabilizer111. Discharge of the fluid from the balloon C moves the second ring110in the proximal end direction by using a force of contracting the balloon C in the longitudinal axis direction of the first inner shaft102, so as to return the stabilizer111to the closed state.

In another modified configuration, the first ring109may be mounted to the outer circumferential surface of the first inner shaft102to be slidably movable in the longitudinal axis direction of the first inner shaft102, and the second ring110may be fixed to the outer circumferential surface of the first inner shaft102. This modified configuration moves the first ring109in the proximal end direction of the first inner shaft102by utilizing a fluid-based pressing force. In this modification, the first ring109is placed on the proximal end side of the distal end of the first inner shaft102. For example, a balloon (hereinafter referred to as balloon D) may be mounted to the outer circumferential surface of the first inner shaft102, and the distal end of the first ring109may be mounted to a proximal end of the balloon D.

In this modified configuration, injection of a fluid into the balloon D expands the balloon D and moves the first ring109in the proximal end direction of the first inner shaft102by using a force of expanding the balloon D in the longitudinal axis direction of the first inner shaft102, so as to expand the stabilizer111. Discharge of the fluid from the balloon D moves the first ring109in the distal end direction by using a force of contracting the balloon D in the longitudinal axis direction of the first inner shaft102, so as to return the stabilizer111to the closed state.

(8) In the above embodiment, the stabilizer opening/closing mechanism (described above in Modification (3)) employs the configuration of moving the second ring110in the distal end direction by means of the first wire112aand the second wire112bto expand the stabilizer111(as shown inFIG.2BandFIG.2C).

A modification may employ a stabilizer that stores in advance the shape in the open state of the stabilizer111(hereinafter referred to as stabilizer B), in place of the stabilizer111and may employ a hollow outer sheath in a cylindrical shape to cover the outer circumference of the first inner shaft102and the stabilizer B in the open state and thereby forcibly set the stabilizer B in the closed state, in place of the first wire112aand the second wire112b.

In this modification, in place of the first wire shaft117aand the second wire shaft117b(shown inFIG.3), a hollow outer sheath shaft is inserted into the outer lumen113of the outer shaft101to surround the first inner shaft102. The outer sheath is configured to be movable in the longitudinal axis direction of the first inner shaft102between the outer circumferential surface of the first inner shaft102and an inner circumferential surface of the outer sheath shaft.

This modified configuration releases the stabilizer B to the open state by moving the outer sheath along the outer circumferential surface of the first inner shaft102to a proximal end side of the stabilizer B.

(9) In some cases, the stabilizer111may be caught by calcified tissue of CTO or by a stent placed in a blood vessel, so that the plasma catheter100may be stuck.

The stabilizer opening/closing mechanism (described above in Modification (3)) may be provided with a mechanism to release the plasma catheter100from the stuck state. For example, two slits may be formed in the first ring109in the longitudinal axis direction of the plasma catheter100, so that the first ring109is separable into two. In another example, a fragile portion such as a cut may be provided in the distal end of each of the first stabilizer piece111aand the second stabilizer piece111b(shown inFIGS.2D to2F). Even when the stabilizer111is caught, this modified configuration cuts off the first ring109and readily releases the plasma catheter100by operating the first dial105aof the adjuster105of the plasma catheter100(shown inFIG.1) to pull the first wire112aand the second wire112btoward the proximal end side. In this modified configuration, the first ring109is joined with the first inner shaft102by crimping.

When the first ring109is not cut off by pulling the first wire112aand the second wire112b, another guide wire may be inserted from the opening102ainto the first inner lumen115of the first inner shaft102under guiding of the imaging sensor200to be placed in periphery from the opening104aof the distal-end tip104. A small-diameter balloon may be inserted along this guide wire into the first inner lumen115of the first inner shaft102and expanded, to cut off the first ring109.

Providing the cut at the distal end of the first stabilizer piece111aand/or the second stabilizer piece111benables the first stabilizer piece111aand/or the second stabilizer piece111bto be readily cut off from the first ring109and thereby readily releases the plasma catheter100.

(10) In the embodiment described above, the first stabilizer piece111aand the second stabilizer piece111bare formed in the straight shape extended in the longitudinal axis direction of the inner shaft102(as shown inFIGS.2D to2F).

Instead of this straight shape, the first stabilizer piece111amay be configured to have a large width portion between a distal end and a proximal end thereof. Similarly, the second stabilizer piece111bmay be configured to have a large width portion between a distal end and a proximal end thereof. The respective large width portions of the first stabilizer piece111aand the second stabilizer piece111bmay have a circular arc shape, a rectangular shape or a trapezoidal shape.

Instead of this straight shape, the first stabilizer piece111aand the second stabilizer piece111bmay be respectively configured to be curved.

The first stabilizer piece111aand the second stabilizer piece111bmay be respectively provided with slits. Providing the slits enables the first stabilizer piece111aand the second stabilizer piece111bto be readily opened and closed.

(11) In the above embodiment, the shape of the first stabilizer piece111ain the open state in the bottom view (hereinafter referred to as “bottom view open shape) is half the hexagonal shape (as shown inFIG.2C). More specifically, the first stabilizer piece111aand the second stabilizer piece111bare respectively in the trapezoidal shape in bottom view (as shown inFIG.2C).

Instead of the trapezoidal shape, the bottom view open shape of the first stabilizer piece111amay be an arc shape such that a point present on the first stabilizer piece111aand farthest from the first inner shaft102is located at a position closer to the distal end than the proximal end of the first stabilizer piece111a. Similarly, the bottom view open shape of the second stabilizer piece111bmay be an arc shape such that a point present on the second stabilizer piece111band farthest from the first inner shaft102is located at a position closer to the distal end than the proximal end of the second stabilizer piece111b.

Each of the bottom view open shapes of the first stabilizer piece111aand the second stabilizer piece111bmay be a rectangular shape (half of an oblong shape or a square shape) or a circular arc shape (approximately semicircular shape), instead of the trapezoidal shape of the above embodiment or the above arc shape.

FIG.7is a diagram illustrating another example of use of the plasma guide wire CTO system1in the case where CTO formed in coronary artery is canalized by an antegrade approach. The operator first delivers the delivery guide wire70to the true lumen84on the proximal end side (proximal side) of the CTO81. As in the example ofFIG.6B, the operator subsequently inserts the proximal end of the delivery guide wire70into the plasma catheter100and transports the plasma catheter100along the delivery guide wire70to the true lumen84on the proximal end side (proximal side) of the CTO81. At this moment, the operator transports the plasma catheter100in the state in which the transducer201of the imaging sensor200is located near to the proximal end side of the opening102ain the first inner lumen115. The operator checks an image of the coronary artery80from the transducer201on the display302and locates the plasma catheter100at an optimum (or suitable) position for penetration by the plasma guide wire400, while transporting the plasma catheter100. The operator then refers to the position of the delivery guide wire70on the display302and rotates the plasma catheter100such that the opening103aas the outlet of the plasma guide wire400is mutually opposed to a target site of ablation. Accordingly, like the example ofFIG.6B, in the example ofFIG.7, the delivery guide wire70serves as a landmark to locate the plasma catheter100at the optimum position.

The operator subsequently operates the first dial105aof the adjuster105to move the second ring110in the distal end direction via the first wire112aand the second wire112band expand the stabilizer111(the expanded state of the stabilizer111is not illustrated inFIG.7). The stabilizer111is expanded to press the biological tissue (for example, blood vessel wall or CTO) and thereby fix the plasma catheter100.

As in the example ofFIG.6C, the operator subsequently uses the imaging sensor200to confirm successful fixation of the plasma catheter100, removes the delivery guide wire70, and moves the imaging sensor200back and forth along the longitudinal axis direction of the first inner shaft102to observe and determine a site optimum for penetration into the CTO81. After that, as shown inFIG.7, the operator causes the plasma guide wire400to protrude from the opening103aof the second inner lumen116and guides the distal end of the plasma guide wire400to the target site of ablation, while checking the image of the coronary artery80from the transducer201on the display302.

As in the example ofFIG.6D, the operator subsequently operates the RF generator500to output high frequency power between the first electrode106and the distal-end tip403of the plasma guide wire400and performs ablation of the CTO81with the fibrous film83formed on the distal end side or other words, the CTO81with fibrosis of the distal end side (hereinafter the CTO81with the fibrous film83formed on the distal end side is simply referred to as CTO81). The operator continuously performs ablation from the proximal end side (proximal side) to the distal end side (distal side) of the CTO81to connect the true lumen84on the proximal end side with the true lumen84on the distal end side and thereby canalize the CTO.

The plasma guide wire CTO system1of the first embodiment is not limitedly used for the approach from the false lumen82to the true lumen84(subintimal approach) described above with reference toFIGS.6A to6Dbut is also used for the approach to pass through the CTO81in the true lumen84. This configuration enables the operator to perform ablation, while checking the target site of ablation on the image of the imaging sensor200. This configuration suppresses the blood vessel wall from being mistakenly damaged especially at a start of ablation in the vicinity of an end face of the CTO81and improves the safety. This configuration also enables a target site optimum for ablation, for example, a soft portion of CTO, to be found at the start of ablation, thus allowing for efficient procedure and shortening the manipulation time. In the plasma guide wire CTO system1of the first embodiment, for example, the process of rotating the plasma catheter100for positioning and the process of expanding the stabilizer111to fix the plasma catheter100may be omitted.

In the first embodiment described above, the plasma guide wire CTO system1is one example of the “recanalization catheter system”. The plasma catheter100is one example of the “catheter”. The first inner lumen115is one example of the “first lumen”, and the second inner lumen116is one example of the “second lumen”. The outer shaft101, the first inner shaft102located on the proximal end side of a distal end face of the outer shaft101, the second inner shaft103, the first and the second wire shafts117aand117b, and the sealing member114are one example of the “shaft”. The first inner shaft102located on the distal end side of the distal end face of the outer shaft101is one example of the “extended shaft portion”. The imaging sensor200is one example of the “sensor”. The imaging sensor200, the delivery guide wire70and the plasma guide wire400are one example of the “medical device”. The opening104ais one example of the “first opening”, the opening102ais one example of the “second opening”, and the opening103ais one example of the “third opening”. The first ring109, the second ring110and the stabilizer111are one example of the “expanding contracting portion”. The first and the second wires112aand112band the first and the second wire pieces111cand111dare one example of the “actuating portion”. The braids108are one example of the “reinforcing member”. The first electrode106is one example of the “electrode”. The false lumen herein denotes any isolated cavity formed by the guide wire, other than the true lumen.

Examples of Advantageous Effects

As described above, in the plasma guide wire CTO system1of the first embodiment, the plasma catheter100(catheter) is provided with the shaft including the first inner lumen115(first lumen) and the second inner lumen116(second lumen) arranged to be adjacent to the first inner lumen115. As shown inFIG.6BandFIG.6D, this configuration enables the imaging sensor200(sensor) and the medical device such as the delivery guide wire70and the plasma guide wire400(guide wire) to be simultaneously held in one catheter (in the plasma catheter100).

The plasma catheter100of the first embodiment (catheter) is provided with the first inner shaft102(extended shaft portion) having the distal end portion that is extended toward the distal end side from the distal end portion of the second inner lumen116(second lumen). For example, as shown inFIGS.6B to6D, this configuration enables the distal end portion of the medical device inserted into the second inner lumen116(for example, the delivery guide wire70shown inFIG.6Bor the plasma guide wire400shown inFIG.6D) to be observed with the imaging sensor200by inserting the imaging sensor200into the first inner lumen115(first lumen) and placing the transducer201of the imaging sensor200(portion configured to transmit and receive ultrasonic waves to and from biological tissue) in the first inner lumen115in the first inner shaft102. This configuration enables the operator to recognize in real time the state of the inside of a biological lumen (for example, CTO) and the position of the distal end portion of, for example, the delivery guide wire70or the plasma guide wire400by only using a two-dimensional image formed by the imaging sensor200. Accordingly, the plasma catheter100of the first embodiment allows for a procedure under guiding of the imaging sensor200without requiring the skill of separate intravascular manipulation of a plurality of devices and the skill of three-dimensional reconstruction of an IVUS image (imaging sensor image) and an X-ray image, which are conventionally required in the procedure under guiding of the imaging sensor200(for example, IVUS guide). Furthermore, the plasma catheter100of the first embodiment allows for a procedure only by referring to the image of the imaging sensor200and thereby reduces the frequency of obtaining X-ray images. This is expected to reduce the radiation exposure of the operator and the patient in X-ray photography and to reduce the use amount of a contrast agent in X-ray photography.

The plasma catheter100of the first embodiment (catheter) is provided with the first electrode106(electrode) that is placed on the surface of the outer shaft101. As shown inFIG.6D, this configuration allows for ablation of biological tissue using the plasma flow by insertion of the plasma guide wire400into the second inner lumen116(second lumen). This configuration allows for more reliable penetration of the biological tissue, compared with penetration of the biological tissue using an ordinary guide wire and is thus expected to improve the success rate of CTO canalization. In other words, even in the case that conventionally requires a shift to a retrograde approach for canalization, the combined use of the plasma catheter100of the first embodiment with the plasma guide wire400enables stable treatment by only an antegrade approach. Additionally, this antegrade approach is expected to shorten the manipulation time, compared with the retrograde approach.

As a result, the plasma catheter100of the first embodiment (catheter) improves the convenience of the procedure under guiding of the imaging sensor200(sensor) and is expected to reduce the radiation exposure, to reduce the use amount of the contrast agent, to improve the success rate of the procedure by the antegrade approach and to shortens the manipulation time.

In the plasma catheter100of the first embodiment (catheter), the opening104a(first opening) that communicates with the first inner lumen115(first lumen) in the distal end portion and the opening102a(second opening) that communicates with the first inner lumen115in a side face on the proximal end side of the opening104aand on the side opposed to the second inner lumen116(second lumen) are respectively formed in the first inner shaft102(extended shaft portion). The opening103a(third opening) that communicates with the second inner lumen116in the distal end portion is formed in the shaft. As shown inFIG.6B, the delivery guide wire70is inserted from the opening104ainto the first inner lumen115, is led out from the opening102a, and is then inserted from the opening103ainto the second inner lumen116, so as to be fixed in the distal end portion of the shaft. Fixation of the delivery guide wire70causes the delivery guide wire70to be continuously located in a fixed direction on the image of the imaging sensor200(sensor). As described above with reference toFIG.6B, the operator moves the plasma catheter100in the longitudinal direction and rotates the plasma catheter100relative to the delivery guide wire70as the basis, while referring to the image of the imaging sensor200. This controls the position of a target site for ablation by the plasma guide wire400, relative to the plasma catheter100to an optimum position (optimum angle).

In the plasma catheter100of the first embodiment (catheter), the distal end portion of the first inner lumen115(first lumen) for the imaging sensor200(sensor) is used for fixation of the delivery guide wire70as shown inFIG.6B. In other words, the first inner lumen115is shared by the delivery guide wire70and the imaging sensor200. This configuration allows for reduction of the diameter of the plasma catheter100and enables the plasma catheter100to be readily inserted into a biological lumen (for example, inside of the coronary artery or inside of the CTO), compared with a configuration of providing a separate lumen for fixation of the delivery guide wire70.

Furthermore, the plasma catheter100of the first embodiment (catheter) is also provided with the stabilizer111(expanding contracting portion) that is expandable and contractible in the radial direction. After the plasma catheter100is moved in the longitudinal direction and rotated to be positioned, the stabilizer111is expanded, so that the plasma catheter100is fixed at the position as shown inFIG.6C. Fixing the plasma catheter100prior to ablation by the plasma guide wire400(shown inFIG.6D) improves the operability of the plasma guide wire400in a biological lumen.

The stabilizer111(expanding contracting portion) is placed in the first inner shaft102(extended shaft portion) having the first inner lumen115(first lumen). Accordingly, when the stabilizer111is made of a material having a difference of an acoustic impedance from the acoustic impedance of the biological tissue, for example, the process of expanding the stabilizer111is more clearly observable by the imaging sensor200(sensor) inserted into the first inner lumen115. This configuration enables the stabilizer111to be expanded safely, while reducing a potential damage in a biological lumen caused by excessive expansion of the stabilizer111. Furthermore, even after fixation of the plasma catheter100shown inFIG.6C, the imaging sensor200is movable in the first inner lumen115to move an image obtaining portion. Accordingly, this configuration enables a positional relationship between the distal-end tip403(distal end portion9of the plasma guide wire400and a target site for ablation to be observed by adjusting the image obtaining portion (transducer201) to the distal end portion of the plasma guide wire400. This allows for penetration of the target site, while reducing the frequency of obtaining X-ray images.

Moreover, in the plasma catheter100of the first embodiment (catheter), when the stabilizer111(expanding contracting portion) is made of a material having a larger acoustic impedance than the acoustic impedance of the biological tissue, the stabilizer111may serve as an orientation marker to check the orientation and the direction of the plasma catheter100. When the stabilizer111is made of a radiopaque material, the stabilizer111may serve as an orientation marker to check the orientation and the direction of the plasma catheter100by imaging of the stabilizer111on an X-ray image obtained by X-ray photography.

Additionally, in the plasma catheter100of the first embodiment (catheter), the diameter of the first inner lumen115(first lumen) is larger than the diameter of the second inner lumen116(second lumen) as shown inFIG.3. In general, the imaging sensor200(sensor) inserted into the first inner lumen115has a larger diameter than the diameter of the medical device (for example, the delivery guide wire70or the plasma guide wire400) inserted into the second inner lumen116. In the plasma catheter100of the first embodiment, the diameter of the first inner lumen115is larger than the diameter of the second inner lumen116. The respective diameters of the first inner lumen115and the second inner lumen116may be determined according to the diameters of the respective devices inserted into the respective lumens. This configuration reduces potential errors in insertion of the devices and reduces the diameter of the plasma catheter100, compared with a configuration that includes lumens of an identical diameter.

Furthermore, the plasma catheter100of the first embodiment (catheter) is provided with the braids108(reinforcing member) placed in a thick wall portion of the shaft as shown inFIG.3. This configuration improves the torque transmission performance of the plasma catheter100. The braids108are made of a material having electrical conductivity and are connected with the first electrode106(electrode) to establish electrical continuity with the second electrode107. This configuration reduces the diameter of the plasma catheter100, compared with a configuration provided with a separate member to establish electrical continuity with the first electrode106. Additionally, when the braids108(reinforcing member) are made of a radiopaque material, this allows for imaging of the braids108on an X-ray image obtained by X-ray photography.

B. Second Embodiment

FIG.8is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system1A according to a second embodiment. A lower part ofFIG.8is a schematic bottom view illustrating a portion surrounded by a broken line frame in an upper part thereof. The plasma guide wire CTO system1A of the second embodiment is provided with a plasma catheter100A usable as a rapid exchangeable-type. The plasma catheter100A differs from the plasma catheter100described in the first embodiment by an outer shaft101A provided in place of the outer shaft101and a second inner shaft103A provided in place of the second inner shaft103. As shown in the lower part ofFIG.8, in the outer shaft101A and the second inner shaft103A, an opening101athat communicates with the second inner lumen116is formed in a side face on a proximal end side of an opening103a. The opening101ais one example of the “fourth opening”. The opening101ais formed on an identical side with an opening102aand is open to an approximately identical direction. In the bottom view of the lower part ofFIG.8and the bottom views ofFIG.2BandFIG.2C, the opening102a, the opening103aand the opening101aare formed to be located on a virtual straight line that is extended in an approximately identical direction with longitudinal axis directions of the first inner shaft102and the outer shaft101A.

FIG.9is a diagram illustrating one example of use of the plasma guide wire CTO system1A according to the second embodiment. The plasma guide wire CTO system1A of the second embodiment may be used by a similar procedure to that ofFIG.6Bin the state in which the proximal end side of the delivery guide wire70inserted into the second inner lumen116further protrudes out from the opening101a. The plasma catheter100A may be provided with the opening101a(fourth opening) that is formed in the side face on the proximal end side of the opening103a(third opening) and that communicates with the second inner lumen116(second lumen) for a medical device such as the delivery guide wire70. This configuration has similar advantageous effects to those of the first embodiment. The plasma catheter100A of the second embodiment may be used as the rapid exchangeable-type catheter. This extends the applicable range of the procedure and further improves the usability.

C. Third Embodiment

FIG.10is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system1B according to a third embodiment.FIG.11is a schematic diagram illustrating a section of a plasma catheter100B taken along a line B-B inFIG.10. The plasma guide wire CTO system1B of the third embodiment includes the plasma catheter100B having a balloon as an expanding contracting portion. The plasma catheter100B differs from the plasma catheter100described in the first embodiment by a balloon150serving as the expanding contracting portion and an inflation shaft151and a fill port159serving as the actuating portion, in place of the first ring109, the second ring110, the first and the second stabilizer pieces111aand111b, the first and the second wire pieces111cand111d, the first and the second wires112aand112b, the first and the second wire shafts117aand117band the first dial105aof the adjuster105.

The balloon150is a tubular member that is expandable and contractible in a radial direction (direction perpendicular to a longitudinal direction) of the plasma catheter100B. Like the first wire shaft117aof the first embodiment, the inflation shaft151is a hollow long member having an approximately circular cross section and is inserted into the outer shaft101. As shown inFIG.10, a distal end side of the inflation shaft151is placed inside of the balloon150, and a proximal end side of the inflation shaft151is connected with the fill port159that is provided in a proximal end face of the adjuster105. The balloon150has a distal end portion that is joined with the first inner shaft102and a proximal end portion that is joined with the first inner shaft102and the inflation shaft151, so as to be internally sealed. The balloon150is made of a material that is expandable and contractible with a change in internal pressure and that has flexibility for suppressing a potential intravascular damage and hardness for fixing the plasma catheter100B. The balloon150may be made of, for example, a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, a polyester such as polyethylene terephthalate, a thermoplastic resin such as polyvinyl chloride, ethylene-vinyl acetate copolymer, crosslinked ethylene-vinyl acetate copolymer or polyurethane, polyamide elastomer, polyolefin elastomer, polyurethane elastomer, silicone rubber, or latex rubber.

In the plasma guide wire CTO system1B of the third embodiment, the operator injects a fluid from the fill port159to expand the balloon150and thereby fixes the plasma catheter100B in the coronary artery80, instead of operating the first dial105aof the adjuster105to expand the stabilizer111. The cross sectional shape of the balloon150in the expanded state is preferably an approximately elliptical shape. The plasma catheter100B may have an expanding contracting portion that has a different configuration from that of the stabilizer pieces. For example, the balloon150may be formed in a self-expandable type and may be provided with a sleeve configured to cover the balloon150and thereby keep the balloon150in the contracted state, in place of the inflation shaft151and the fill port159. In this configuration, the operator causes the balloon150to be exposed from the sleeve and thereby fixes the plasma catheter100B in the coronary artery80, instead of expanding the stabilizer111. This configuration also has similar advantageous effects to those of the first embodiment.

D. Fourth Embodiment

FIGS.12A and12Bare schematic diagrams illustrating expanding contracting portions according to a fourth embodiment.FIG.12Aillustrates one example of the expanding contracting portion according to the fourth embodiment. A plasma catheter100C of the fourth embodiment is provided with a stabilizer111C in a different configuration from that of the first embodiment.

The stabilizer111C shown inFIG.12Aincludes a third stabilizer piece111e, in addition to a first stabilizer piece111aand a second stabilizer piece111bdescribed in the first embodiment. In a cross section A of the stabilizer111C shown by the broken line, the first stabilizer piece111aand the second stabilizer piece111bare arranged to be opposed to each other. A virtual line L (one-dot chain line) connecting respective centers of the first and the second stabilizer pieces111aand111bis defined on the cross section A. The third stabilizer piece111eis placed in one area out of two areas that are adjacent to each other across the virtual line L as the boundary (these areas are called “upper area” and “lower area” for descriptive purposes). More specifically, in the illustrated example, the third stabilizer piece111eis placed in the upper area on the cross section A and is arranged at a position that has approximately identical lengths from the first stabilizer piece111aand the second stabilizer piece111b. This configuration enables the stabilizer111C to serve as an orientation marker of the higher accuracy for checking the orientation and the direction of the plasma catheter100C on an image of the imaging sensor200.

The stabilizer111C shown inFIG.12Bfurther includes a fourth stabilizer piece111f, in addition to the third stabilizer piece111edescribed above. The fourth stabilizer piece111fis placed in the other area out of the two areas adjacent to each other across the virtual line L as the boundary. More specifically, in the illustrated example, the fourth stabilizer piece111fis placed in the lower area on the cross section A and is arranged at a position that has approximately identical lengths from the first stabilizer piece111aand the second stabilizer piece111b. The number of stabilizer pieces provided in the stabilizer111C is determined arbitrarily and may be one or may be three or more. These configurations have similar advantageous effects to those of the first embodiment.

E. Fifth Embodiment

FIGS.13A and13Bare schematic diagrams illustrating expanding contracting portions according to a fifth embodiment.FIG.13Aillustrates one example of the expanding contracting portion according to the fifth embodiment. A plasma catheter100D of the fifth embodiment is provided with a stabilizer111D in a different configuration from that of the first embodiment.

The stabilizer111D shown inFIG.13Aincludes a first ring109D, in place of the first ring109described in the first embodiment. The first ring109D has two separating portions109sprovided in a longitudinal axis direction of the plasma catheter100D. During the procedure described above with reference toFIGS.6A to6D, the stabilizer111dmay be caught by calcified tissue of the CTO81or by a stent placed in a blood vessel, so that the plasma catheter100D is likely to be stuck in the coronary artery80. In this case, the separating portions109sserve to separate the stabilizer111D as shown on the right side ofFIG.13A, so as to release the plasma catheter100D. The separating portions109smay be configured as cuts (slits) provided in a thick wall portion of the first ring109D. The separating portions109smay also be configured as fragile portions by reducing the wall thickness of part of the first ring109D, by providing through holes or by changing the material.

When the stabilizer111D is caught, the operator operates the first dial105aof the adjuster105(shown inFIG.1) of the plasma catheter100D to pull the first and the second wires112aand112btoward the proximal end side. This causes tears at the separating portions109sto separate the first ring109D as shown on the right side ofFIG.13A. As a result, the operator can readily release the plasma catheter100D. Providing the respective separating portions109sat illustrated positions causes the respective parts of the torn first ring109D to be attached to the first and the second stabilizer pieces111aand111b. This configuration suppresses any part of the torn first ring109D from being left in the body.

FIG.13Billustrates another example of the expanding contracting portion according to the fifth embodiment. In the stabilizer111D shown inFIG.13B, two separating portions111sare formed at boundaries between the first ring109D and the first and the second stabilizer pieces111aand111b. The first ring109D is joined with the surface of the first inner shaft102, for example, by pressure bonding or by using an adhesive. Like the separating portions109s, the separating portions111smay be configured by cuts or by fragile portions. As in the case ofFIG.13A, when the stabilizer111D is caught, the operator pulls the first and the second wires112aand112btoward the proximal end side. This causes tears at the separating portions111sto separate the first ring109D as shown on the right side ofFIG.13B. The first ring109D is joined with the surface of the first inner shaft102. This configuration suppresses any part of the torn first ring109D from being left in the body.

The expanding contracting portion may have various modified configurations and may have a configuration other than those described in the first embodiment. Such configurations also have similar advantageous effects to those of the first embodiment. Even when the plasma catheter100D is stuck in the coronary artery80, the expanding contracting portions of the fifth embodiment can readily release the plasma catheter100D.

F. Sixth Embodiment

FIGS.14A to14Care schematic diagrams illustrating expanding contracting portions according to a sixth embodiment.FIG.14Aillustrates one example of the expanding contracting portion according to the sixth embodiment.FIG.14BandFIG.14Cillustrate other examples of the expanding contracting portion according to the sixth embodiment. A plasma catheter100E of the sixth embodiment is provided with a stabilizer111E in a different configuration from that of the first embodiment. The stabilizer111E of the sixth embodiment includes first and second stabilizer pieces111aE and111bE, in place of the first and the second stabilizer pieces111aand111bdescribed in the first embodiment. Each of the first and the second stabilizer pieces111aE and111bE shown inFIGS.14A to14Chas a wide portion111pthat is formed wide between a distal end portion and a proximal end portion. The wide portion111pmay be formed in a circular arc shape (approximately elliptical shape) shown inFIG.14A, in a rectangular shape shown inFIG.14Bor in a trapezoidal shape shown inFIG.14C.

FIGS.15A and15Bare schematic diagrams illustrating expanding contracting portions according to the sixth embodiment.FIGS.15A and15Billustrate other examples of the expanding contracting portion according to the sixth embodiment. Each of the first stabilizer piece111aE and the second stabilizer piece111bE shown inFIG.15Ahas a curved portion111wthat is formed by bending the stabilizer piece in an approximately S shape between a distal end portion and a proximal end portion. The curved portion111wmay be formed in any of various shapes, for example, an approximately C shape or an approximately O shape. Each of the first stabilizer piece111aE and the second stabilizer piece111bE shown inFIG.15Bhas a cut (slit)111sthat is extended in a longitudinal direction of the plasma catheter100E. In the example ofFIG.15B, when the first and the second wires112aand112bare pushed in toward the distal end portion by operation of the first dial105aof the adjuster105(shown inFIG.1), the first and the second stabilizer pieces111aE and111bE are bent in the vertical direction from the respective cuts111sto be expanded as shown on the right side of the drawing.

The expanding contracting portion may have various modified configurations and may have a configuration other than those described in the first embodiment. Such configurations also have similar advantageous effects to those of the first embodiment. In the expanding contracting portions of the sixth embodiment, the wide portions111pas shown inFIGS.14A to14C, the curved portions111was shown inFIG.15Aor the first and the second stabilizer pieces111aE and111bE bent in the vertical direction as shown inFIG.15Bengage with the biological tissue and thereby more reliably fix the plasma catheter100E in the coronary artery80.

G. Seventh Embodiment

FIGS.16A to16Care schematic diagrams illustrating distal end portions of a plasma catheter100F according to a seventh embodiment.FIG.16Ais a schematic bottom view illustrating one example of the distal end portion of the plasma catheter100F.FIGS.16B and16Care schematic bottom views illustrating other examples of the distal end portion of the plasma catheter100F. The plasma catheter100F of the seventh embodiment is provided with a stabilizer111F that is expanded in different shapes from that of the first embodiment. A bottom view shape of the stabilizer111F in the expanded state may be an approximately teardrop shape as shown inFIG.16A, an approximately rectangular shape as shown inFIG.16Bor an approximately circular shape as shown inFIG.16C. In the case of the approximately teardrop shape shown inFIG.16A, it is preferable that a portion having a longest distance L1from the surface of the first inner shaft102to the stabilizer111F (first and second stabilizer pieces111aand111b) is located on a distal end side of the middle of the stabilizer111F. The expanding contracting portion in the expanded state may have various modified configurations and may have a configuration other than those described in the first embodiment. Such configurations also have similar advantageous effects to those of the first embodiment.

H. Eighth Embodiment

FIGS.17A and17Bare schematic diagrams illustrating a distal end portion of a plasma catheter100G according to an eighth embodiment.FIG.17Ais a schematic side view illustrating one example of the distal end portion of the plasma catheter100G.FIG.17Bis a schematic bottom view illustrating one example of the distal end portion of the plasma catheter100G.FIG.18is a schematic diagram illustrating a cross section of the plasma catheter100G taken along a line C-C inFIG.17A. The plasma catheter100G of the eighth embodiment has an integral shaft of an outer shaft and first and second inner shafts.

More specifically, in place of the outer shaft101, the first inner shaft102, the second inner shaft103and the sealing member114described in the first embodiment, the plasma catheter100G includes an integrally molded shaft101G (shown inFIG.18). As shown inFIG.18, a first inner lumen115for insertion of the imaging sensor200and a second inner lumen116for insertion of the delivery guide wire70and the plasma guide wire400are formed inside of the shaft101G. An electrically conductive element wire108G is also embedded inside of the shaft101G to connect the first electrode106with the second electrode107such as to establish electrical continuity.

A distal end portion of the shaft101G is provided with an extended shaft portion102G that includes the first inner lumen115and that is extended toward a distal end side of the distal end portion of the second inner lumen116. An opening104ais formed in a distal end face of the extended shaft portion102G. An opening102ais formed in a side face of the extended shaft portion102G on a side opposed to the second inner lumen116. An opening103athat communicates with the second inner lumen116is formed in a distal end face of the shaft101G. The extended shaft portion102G may be integrally molded with the shaft101or may be separately formed and joined with a distal end portion of the shaft101G.

The plasma catheter100G of the eighth embodiment may be provided or may not be provided with the stabilizer111(first and second stabilizer pieces111aand111b), the first and the second rings109and110, the first and the second wire pieces111cand111d, the first and the second wires112aand112b, the first and the second wire shafts117aand117b, the first dial105a, the distal-end tip104and the braids108described in the first embodiment, other than the outer shaft101, the first inner shaft102, the second inner shaft103and the sealing member114described above. The element wire108G may not be embedded in the shaft101G but may be placed on the surface of the shaft101G. The plasma catheter100G may have various modified configurations and may have a configuration other than those described in the first embodiment. Such configurations also have similar advantageous effects to those of the first embodiment.

I. Ninth Embodiment

FIG.19is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system1H according to a ninth embodiment.FIG.20is a schematic diagram illustrating a section of a plasma catheter100H taken along a line D-D inFIG.19. The plasma guide wire CTO system1H of the ninth embodiment includes the plasma catheter100H, in place of the plasma catheter100described in the first embodiment. For convenience of illustration, the plasma guide wire400connected with the cable connector11is omitted from the illustration inFIG.19. As shown inFIG.20, the plasma catheter100H is not provided with the second inner shaft103described in the first embodiment. Accordingly, the plasma catheter100H is configured without the second inner lumen116and the opening103athat are formed by the second inner shaft103and is configured to have only the first inner lumen115used for insertion of a medical device.

The plasma guide wire CTO system1H of the ninth embodiment achieves canalization of CTO as follows. The proximal end of the delivery guide wire70is inserted from an opening104ato pass through the inner lumen of the distal-end tip104and the first inner lumen115of the first inner shaft102(shown inFIG.20) and protrudes out from an opening102aof the first inner shaft102. The plasma catheter100H is transported along the delivery guide wire70to the false lumen82. At this moment, the operator places the plasma catheter100H at an optimum position for penetration into the true lumen by the plasma guide wire400, while checking the image of the coronary artery80by the imaging sensor200inserted into the first inner lumen115. After placing the plasma catheter100H at the optimum position, the operator rotates the plasma catheter100H as needed with regard to the position of the delivery guide wire70on the image by the imaging sensor200as the indication.

The operator subsequently operates the first dial105ato expand the stabilizer111. Expansion of the stabilizer111fixes the plasma catheter100H. The operator then removes the delivery guide wire70and the imaging sensor200and newly inserts the plasma guide wire400into the first inner lumen115. The operator transports the distal end portion of the plasma guide wire400to a distal end portion of the plasma catheter100H and causes the distal end portion of the plasma guide wire400to protrude out from the opening102aor from the opening104a. When the optimum site for penetration is located near to the distal end portion of the plasma catheter100H, it is preferable to protrude the plasma guide wire400from the opening104a. When the optimum site for penetration is located near to a side face of the plasma catheter100H, on the other hand, it is preferable to protrude the plasma guide wire400from the opening102a. The operator then operates the RF generator500to cause streamer discharge at the distal-end tip403of the plasma guide wire400and performs ablation of the CTO81.

The plasma catheter100H may have various modified configurations. For example, the number of lumens for insertion of a medical device may be one or may be three or more. In the plasma guide wire CTO system1H of the ninth embodiment, the plasma catheter100H (catheter) is provided with one first inner lumen115(lumen, shown inFIG.20) for insertion of a medical device. This configuration reduces the diameter of the plasma catheter100H. The distal end portion of the shaft is provided with the first inner shaft102(extended shaft portion) having the distal end portion that is extended toward the distal end side of the distal end portion of the outer shaft101. This configuration enables inside of the false lumen82to be observed with the higher accuracy by inserting the imaging sensor200(sensor) into the first inner lumen115and placing the transducer201of the imaging sensor200in the first inner lumen115in the first inner shaft102. The first electrode106(electrode) is provided on the outer circumferential surface of the outer shaft101. This configuration allows for ablation of biological tissue using the plasma flow by insertion of the plasma guide wire400into the first inner lumen115. Additionally, after the plasma catheter100H is moved in the longitudinal direction and is rotated to be positioned, the stabilizer111(expanding contracting portion) that is expandable and contractible in the radial direction is expanded, so that the plasma catheter100H is fixed at the position.

The plasma catheter100H of the ninth embodiment is provided with the opening104a(first opening) formed in the distal end portion of the first inner shaft102(extended shaft portion), which is extended toward the distal end side of the distal end portion of the outer shaft101, to communicate with the first inner lumen115(lumen) and with the opening102a(second opening) formed in a side face on a proximal end side of the opening104ato communicate with the first inner lumen115. This configuration enables the proximal end side of the delivery guide wire70to be inserted from the opening104ainto the first inner lumen115, to pass through the first inner lumen115and to protrude out. The plasma catheter100H can thus be used as a rapid exchangeable-type catheter. When the plasma guide wire400is inserted in the first inner lumen115in use, protrusion of the distal end portion of the plasma guide wire400from the opening104afacilitates ablation of biological tissue located in the vicinity of the distal end portion of the plasma catheter100H. Furthermore, protrusion of the distal end portion of the plasma guide wire400from the opening102afacilitates ablation of biological tissue located in the vicinity of the side face of the plasma catheter100H.

J. Tenth Embodiment

FIG.21is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system1J according to a tenth embodiment.FIG.22is a schematic diagram illustrating a section of a plasma catheter100J taken along a line E-E inFIG.21. The plasma guide wire CTO system1J of the tenth embodiment is provided with the plasma catheter100J in place of the plasma catheter100described in the first embodiment and with omission of the imaging sensor200and the imaging console300. As shown inFIG.21, the plasma catheter100J is configured without the respective components corresponding to the expanding contracting portion and the actuating portion described in the first embodiment, i.e., without the first ring109, the second ring110, the first and the second stabilizer pieces111aand111b, the first and the second wire pieces111cand111d, the first and the second wires112aand112band the first and the second wire shafts117aand117b. The plasma catheter100J is also configured without the first inner shaft102, the opening102aand the adjuster105described in the first embodiment.

As shown inFIG.22, in the plasma catheter100J, only the second inner shaft103is inserted into the outer lumen113of the outer shaft101, and an outer circumferential surface of the second inner shaft103is sealed by the sealing member114. As shown inFIG.21, a distal end of the second inner shaft103does not have the inclined shape described in the first embodiment. A distal-end tip104is joined with a distal end of the outer shaft101and the distal end of the second inner shaft103. An opening104aof the distal-end tip104is arranged to communicate with the second inner lumen116of the second inner shaft103. Accordingly, the plasma catheter100J is configured with the opening102aand the opening103ato use only the second inner lumen116for insertion of a medical device.

The plasma guide wire CTO system1J of the tenth embodiment achieves canalization of CTO as follows. The proximal end of the delivery guide wire70is inserted from the opening104ato pass through the second inner lumen116and protrudes out from a proximal end portion of the second inner lumen116. The plasma catheter100J is then transported along the delivery guide wire70to the false lumen82. The operator subsequently places a distal end portion of the plasma catheter100J at an optimum position for penetration into the true lumen, for example, by X-ray photography with injection of a contrast agent through the second inner lumen116. After placing the plasma catheter100J at the optimum position, the operator removes the delivery guide wire70and newly inserts the plasma guide wire400into the second inner lumen116. The operator transports the distal end portion of the plasma guide wire400to the distal end portion of the plasma catheter100J and causes the distal end portion of the plasma guide wire400to protrude out from the opening104a. The operator then operates the RF generator500to cause streamer discharge at the distal-end tip403of the plasma guide wire400and performs ablation of the CTO81.

For example, after removal of the delivery guide wire70, the imaging sensor200described in the first embodiment may be inserted into the second inner lumen116to adjust the position of the plasma catheter100J based on an image by the imaging sensor200, in place of X-ray photography. In another example, when an opening communicating with the second inner lumen116is provided in a side face of the outer shaft101, the proximal end portion of the delivery guide wire70may protrude out from this opening. This enables the plasma catheter100J to be used as a rapid exchangeable-type catheter. In this case, two devices may be inserted simultaneously into the second inner lumen116. For example, the delivery guide wire70may be inserted into a distal end side of the opening in the second inner lumen116, and the imaging sensor200may be inserted into a proximal end side of the opening.

The plasma catheter100J may have various modified configurations. For example, the plasma catheter100J may be configured without the second inner shaft103in addition to the first inner shaft102. In this modification, the outer lumen113of the outer shaft101may not be sealed but may be used as the second inner lumen116. The plasma catheter100J of the tenth embodiment (catheter) is provided with one second inner lumen116(lumen, shown inFIG.22) for insertion of a medical device. This configuration reduces the diameter of the plasma catheter100J. The first electrode106(electrode) is provided on the outer circumferential surface of the outer shaft101(shaft). This configuration allows for ablation of biological tissue using the plasma flow by insertion of the plasma guide wire400into the second inner lumen116(lumen).

K. Eleventh Embodiment

FIG.23is a schematic diagram illustrating the general configuration of a plasma guide wire CTO system1K according to an eleventh embodiment. The plasma guide wire CTO system1K of the eleventh embodiment is provided with a plasma catheter100K in place of the plasma catheter100J described in the tenth embodiment. The plasma catheter100K is configured without the second electrode107described in the tenth embodiment. In the plasma catheter100K, a cable40connected with the RF generator500is embedded in the outer shaft101and is electrically connected with part of a proximal end side of the braids108in the outer shaft101. The plasma guide wire CTO system1K achieves canalization of CTO by the same procedure as that of the tenth embodiment. The plasma catheter100K may have various modified configuration. For example, the plasma catheter100K may be configured without the second electrode107. The configuration of the eleventh embodiment has similar advantageous effects to those of the tenth embodiment.

L. Modifications of Embodiments

The present disclosure is not limited to the embodiments described above but may be implemented by various aspects without departing from the scope of the disclosure. Examples of modifications are given below.

Modification 1

The first to the eleventh embodiments described above illustrate the exemplified configurations of the plasma guide wire CTO systems1,1A,1B,1H,1J and1K. The configurations of the plasma guide wire CTO systems1,1A,1B,1H,1J and1K may, however, be modified in various ways. For example, a sensor configured to obtain an image of biological tissue by a technique other than transmission and reception of ultrasonic waves may be employed as the imaging sensor200. In another example, the plasma guide wire CTO system may be configured as a system that does not use the plasma guide wire400but uses a penetration guide wire for canalization of CTO.

Modification 2

The first to the eleventh embodiments described above show examples of use of the plasma guide wire CTO systems1,1A,1B,1H,1J and1K. The plasma guide wire CTO systems1,1A,1B,1H,1J and1K may, however, be used by a method other than those described above. For example, the plasma guide wire CTO system may be used for a blood vessel other than the coronary artery (for example, brain blood vessel) and may be used in a biological lumen other than the blood vessel. For example, the plasma guide wire CTO system may be used for another treatment other than canalization of CTO or for inspection.

Modification 3

The first to the eleventh embodiments described above illustrate the exemplified configurations of the plasma catheters100and100A to100K. The configurations of the plasma catheters100and100A to100K may, however, be modified in various ways. For example, the first inner lumen115(first lumen) and the second inner lumen116(second lumen) of the plasma catheter may have approximately the same diameters. In another example, the first inner lumen may be configured to have a smaller diameter than the diameter of the second inner lumen. For example, the plasma catheter may be provided with another lumen for a medical device such as a penetration guide wire, in addition to the first lumen and the second lumen.

For example, the opening104a(first opening) communicating with the first inner lumen115may be provided at a position other than the distal end face of the distal-end-tip104(for example, in a side face of the distal-end tip104). Similarly, the opening102a(second opening) communicating with the first inner lumen115may be provided at a position other than the side face of the first inner shaft102on the side opposed to the second inner lumen116. Similarly, the opening103a(third opening) communicating with the second inner lumen116may be provided at a position other than the distal end face of the first inner shaft102(for example, in a side face of the second inner shaft103). For example, part of the opening104a, the opening102a, the opening103aand the opening101amay be omitted, and another non-illustrated opening may be formed.

For example, it is preferable that the portion of the first inner shaft102that is extended toward the distal end side of the distal end portion of the second inner lumen116(second lumen), i.e., the extended shaft portion, is made of polyamide, in terms of satisfying both the ultrasonic transmission of the imaging sensor200and the sufficient wall thickness. It is preferable, on the other hand, that the portion of the first inner shaft102that is extended toward the proximal end side of the distal end portion of the second inner lumen116, the outer shaft101, the second inner shaft103, the sealing member114and the like are made of polytetrafluoroethylene (PTFE), polyimide, tetrafluoroethylene-perfluoroalkoxy ethylene copolymer (PFA), or the like, in terms of providing the sufficient rigidity. It is preferable that the distal-end tip104is made of polyurethane, in terms of providing the sufficient flexibility.

It is preferable that the portion of the first inner shaft102that is extended toward the proximal end side of the distal end portion of the second inner lumen116has a wall thickness of not less than 20 microns, in terms of insulation from the braids108having electrical conductivity. The distal end of the second inner shaft103may not be inclined toward the first inner shaft102but may have a flat distal end face. For example, the plasma catheter may be provided with coil bodies made of a metal material having electrical conductivity as the reinforcing member, in place of the braids108. The plasma catheter may be provided with both the braids108and the coil bodies. For example, the stabilizer111may be coated with a resin having insulating properties or may have a surface coated with a medical agent.

The configurations of the plasma catheters100and100A to100K of the first to the eleventh embodiments and the configurations of the plasma catheters100and100A to100K of Modifications 1 to 3 described above may be combined appropriately. For example, the expanding contracting portion of the configuration described in any of the second embodiment and the fourth to the seventh embodiments may be combined with the plasma catheter of the second embodiment having the fourth opening, the plasma catheter of the eighth embodiment having the shaft, or the plasma catheter of the ninth embodiment without the second inner shaft103. In another example, the expanding contracting portion of the configuration described in any of the modifications of the first embodiment may be combined with the plasma catheter of the second embodiment having the fourth opening, the plasma catheter of the eighth embodiment having the shaft, or the plasma catheter of the ninth embodiment without the second inner shaft103. For example, the configuration without the second electrode107described in the eleventh embodiment may be employed in the plasma catheter described in any of the first to the ninth embodiments.

Various aspects of the present disclosure are described above with reference to some embodiments and modifications. These embodiments and modifications are, however, provided for the purpose of facilitating understanding the aspects of the present disclosure and do not limit the present disclosure in any sense. These embodiments and modifications may be changed, altered and further modified without departing from the scope of the present disclosure, and equivalents thereof are also included in the present disclosure. Any of the technical features may be omitted appropriately unless the technical feature is described as essential in the description hereof.