JP2004275784A - Ultrasonic catheter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic catheter, having such a fine diameter as to be inserted in a body cavity such as a blood vessel or a vas, and having high ultrasonic wave passing performance, bending performance, durability, torque transmission efficiency, and pushability, and excellent running performance in a blood vessel and stability of an ultrasonic image. <P>SOLUTION: This ultrasonic catheter 1 includes: an ultrasonic vibrator 2; a driving shaft 3 provided rather closer to the base end side than the ultrasonic vibrator 2 and adapted to transmit the driving force from a driving source 31 outside the body to the ultrasonic vibrator 2 to cause the ultrasonic vibrator 2 to rotate or reciprocate; and an exterior hollow shaft 4 wrapping the ultrasonic vibrator 2 and the driving shaft 3. The exterior shaft 4 is composed of a base end part 41 formed of polyimide resin and a tip part 42 formed of ultrasonic wave passing material, whereby the ultrasonic wave transmitted by the ultrasonic vibrator 2 passes through the ultrasonic passing material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic catheter used by being inserted into a body cavity such as a blood vessel or a blood vessel.

2. Description of the Related Art Conventionally, there is known an ultrasonic catheter which is inserted into a coronary artery or other small blood vessels of a heart or a blood vessel such as a bile duct to display a lumen cross-sectional image, measure blood flow, and the like (for example, Patent Documents). 1). Since all of the currently used ultrasonic catheters have an outer diameter of 1 mm or more, when using a treatment catheter such as a vascular dilatation balloon catheter, a laser irradiation catheter, or an atherectomy catheter, the treatment catheter is used. It is used interchangeably with. In addition, ultrasonic catheters currently used have insufficient blood vessel running properties by themselves, and therefore, there are many over-the-wire types and monorail wire types which are used by inserting a guide wire into the ultrasonic catheter.

  Therefore, there is a demand for an ultrasonic catheter that can be used simultaneously with a treatment catheter and a guidewire-type ultrasonic catheter that can be inserted further into the periphery and has excellent blood vessel selectivity. In order to satisfy this demand, it is necessary that the outer diameter of the ultrasonic catheter is at least 1 mm or less, preferably 0.4 mm or less.

  By the way, there are two types of ultrasonic catheters: mechanical scanning type and electronic scanning type. In the former structure, an ultrasonic vibrator is provided at the distal end of a catheter inserted into a body cavity, and a signal transmission body for connecting the vibrator and an external electric circuit is built in the catheter. Has a mechanism for mechanically rotating or reciprocating. As this mechanism, there are known a method of directly driving by a small motor built in the distal end of the catheter, and a remote driving method of transmitting a driving force from a driving source outside the catheter by a driving shaft built in the catheter. The latter has a plurality of ultrasonic transducers at the distal end of a catheter inserted into a body cavity, has a switching circuit, and has a signal transmitter for signal transmission with an external circuit.

  From the point of view of the image quality of the ultrasonic image, the mechanical scanning type is said to be superior because a simple ultrasonic beam can be obtained. It has to be a formula. Further, in a system in which a motor is built into a catheter, it is extremely difficult to manufacture a motor that is suitable when the outer diameter of the catheter is 1 mm or less, particularly 0.4 mm or less, and the price is very expensive. . Therefore, in order to effectively reduce the diameter, a mechanical scanning type and remotely driven ultrasonic catheter is considered to be the most suitable.

  In any of the above types of ultrasonic catheters, the outer shaft is made of a so-called catheter material such as a single-layer resin shaft made of nylon, olefin, polyester, or polyurethane, or a multi-layer shaft reinforced with a metal braid or coil. Has been used. In the conventional mechanical scanning type remote drive type ultrasonic catheter having an external total of 1 mm or more, the thickness of the outer shaft can be set to 200 μm or more. An outer shaft can be formed and an ultrasonic catheter with good performance can be obtained.

JP-A-5-329157

  However, in order to obtain an ultrasonic catheter having an outer diameter of 1 mm or less, preferably 0.4 mm or less, the outer diameter of the drive shaft and the ultrasonic vibrator must be set so as not to hinder the rotation or reciprocation of the drive shaft and the ultrasonic vibrator. The width of the armature shaft and the distance between the drive shaft and the ultrasonic transducer and the armature shaft need to be sufficiently large. Therefore, the armature shaft has a small thickness, and has flexibility, kink resistance, torque transmission, and pusher. It is required that the material has excellent operability (indentation property) and that the frictional resistance of the inner surface is as small as possible. However, in order to satisfy this demand, the above-mentioned conventional resin single-layer shafts and multilayer shafts do not have a sufficient wall thickness, and the frictional resistance of the inner surface thereof is relatively large, so that good characteristics can be obtained. Absent.

  Therefore, the present invention provides a small-diameter ultrasonic catheter having high flexibility, high kink resistance, high torque transmission, high pushability (pushability), excellent operability, and a stable ultrasonic image. It is an object of the present invention to provide an ultrasonic catheter having excellent performance that can be performed. Another object of the present invention is to provide an ultrasonic catheter that can reduce the frictional resistance of the inner surface of the exterior shaft. A further object of the present invention is to provide an ultrathin ultrasonic catheter which can be suitably used by being inserted into a treatment catheter such as a vascular dilatation balloon catheter, a laser irradiation catheter, and an atherectomy catheter. Another object of the present invention is to provide an ultrasonic catheter that can be easily manufactured.

The above object is achieved by the present invention described in the following (1) to (5).
(1) An ultrasonic catheter which is used by being inserted into a body cavity, wherein the ultrasonic catheter is provided at a base end side of the ultrasonic transducer, and a driving force from a driving source outside the body is applied to the ultrasonic vibration. A drive shaft for transmitting to the transducer and rotating or reciprocating the ultrasonic vibrator, and a hollow exterior shaft enclosing the ultrasonic vibrator and the drive shaft, wherein the exterior shaft is made of polyimide resin. A base end portion formed by using the base end portion, and a front end portion formed of an ultrasonic wave transmitting material other than the polyimide resin, which is bonded to the base end portion, and an ultrasonic wave transmitted by the ultrasonic vibrator. An ultrasonic catheter through which the ultrasonic wave-permeable material passes.
(2) The ultrasonic catheter according to (1), wherein a boundary between the base end and the distal end of the exterior shaft is located near the ultrasonic vibrator.
(3) The ultrasonic catheter according to the above (1) or (2), wherein the ultrasonic-permeable material is an olefin-based resin.
(4) The ultrasonic catheter according to (3), wherein the olefin-based resin is polyethylene or polypropylene.
(5) The ultrasonic catheter according to any one of (1) to (4), wherein the polyimide-based resin contains 5 to 30% of a fluorine-based resin.

  ADVANTAGE OF THE INVENTION According to this invention, since the ultrasonic wave which the ultrasonic transducer transmits is excellent in the transmissivity from the front-end | tip part of an exterior shaft, a stable ultrasonic image can be obtained. In addition, since it has high tensile strength and high flexibility, it is possible to provide an ultra-fine-diameter ultrasonic catheter which is excellent in operability in a body cavity such as a blood vessel or a minute vessel or in various treatment catheters. Therefore, at the time of insertion into the body cavity, there is no need to replace the ultrasonic catheter and the treatment catheter, and the risk of damage to the blood vessel wall can be reduced, and the measurement in the body cavity can be performed simultaneously or in parallel with the treatment with the treatment catheter. It can be carried out.

  Further, according to the present invention, since the frictional resistance (sliding resistance) of the exterior shaft is sufficiently small, when the drive shaft rotates or reciprocates, or when the drive shaft is used by being inserted into another catheter such as a treatment catheter. An ultrasonic catheter with low dynamic resistance can be provided. Therefore, even when a part of the drive shaft contacts the inner surface of the exterior shaft, the rotation or reciprocation of the drive shaft is not hindered, and a stable ultrasonic image can be obtained.

  Furthermore, according to the present invention, it is possible to insert a long drive shaft and other components into the base end portion of the exterior shaft, assemble, and then join the front end portion and the base end portion of the exterior shaft. By doing so, it becomes easier to manufacture an ultrasonic catheter having an outer shaft.

  When a fluorine resin is contained in the polyimide resin forming the base end of the exterior shaft, the frictional resistance (sliding resistance) at the base end of the exterior shaft can be further reduced, and a more stable ultrasonic image can be obtained. Thus, it is possible to provide an ultrasonic catheter having better operability.

Hereinafter, the present invention will be described based on examples and reference examples shown in the accompanying drawings.

  FIG. 1 is a partial cross-sectional overall side view showing one reference example of the ultrasonic catheter of the present invention, FIG. 2 is an enlarged longitudinal sectional view showing the ultrasonic transducer and the back material of the reference example shown in FIG. 1, and FIG. 4 is an enlarged longitudinal sectional view showing a modified example of the back member, and FIG. 4 is an end view taken along line IV-IV in FIG. FIG. 1 omits an intermediate portion of the ultrasonic catheter. Also, the left side in FIGS. 1, 3 and 4 is referred to as “distal end” and the right side is referred to as “proximal end”.

  The ultrasonic catheter 1 shown in FIG. 1 is an ultrasonic catheter which is used by being inserted into a body cavity. The ultrasonic catheter 1 is provided on an ultrasonic vibrator 2 and a base end side of the ultrasonic vibrator 2. A drive shaft 3 for transmitting the driving force from the ultrasonic transducer 2 to the ultrasonic vibrator 2 to rotate or reciprocate the ultrasonic vibrator 2, and a hollow exterior shaft 4 enclosing the ultrasonic vibrator 2 and the drive shaft 3. The exterior shaft 4 is made of a polyimide resin to have an outer diameter of 1 mm or less and a thickness of 50 μm or less, and the minimum distance between the exterior shaft 4 and the drive shaft 3 is set to 100 μm or less.

The ultrasonic transducer 2 is disposed at the distal end of the ultrasonic catheter 1, and as shown in FIG. 2, a ceramic piezoelectric material such as PZT (lead zirconate titanate), PbTiO ₃ (lead titanate), or PVDF. Electrodes 22 are formed on both surfaces of a piezoelectric body 21 composed of a polymer piezoelectric body such as (polyvinylidene fluoride) or the like and a composite piezoelectric body of the above-mentioned ceramic and polymer by vapor deposition, printing, or the like. As the ultrasonic transducer 2, the radial width t of the ultrasonic catheter 1 is about 0.9 mm or less, preferably about 0.15 to 0.25 mm, and the specific acoustic impedance is 4 × 10 ⁶ to 4 × 10 ⁷ kg / m ² · s.

  It is preferable to provide a back material 5 for absorbing and attenuating unnecessary ultrasonic waves emitted to the back side on the back surface of the ultrasonic transducer 2. The back material 5 is formed of a material having a high ultrasonic attenuation rate, such as a resin material such as an epoxy resin, a polyurethane resin, or an acrylic resin, or a rubber material such as a silicone rubber. The adhesive is provided so as not to cause substantial displacement with the ultrasonic vibrator 2 by the agent. For the purpose of more effectively absorbing and attenuating the ultrasonic waves by the backing material 5, the above materials may contain scatterers (for example, tungsten) having different intrinsic impedances.

  The back material 5 shown in FIG. 2 has, on the back surface thereof, unevenness 51 whose thickness difference D is λ / 4 (λ is the wavelength in the back material at the transmission frequency). The unevenness 51 can cancel the reflected wave from the back surface of the back material 5 by interference, and can reduce the influence of the reflected wave from the back surface.

  The dimensions of the backing material 5 shown in FIG. 2 are about 0.04 to 0.2 mm in thickness, and the dimensions of the unevenness 51 are about 7 to 50 μm in the above D and the width of the projection is about 30 to 200 μm. And the width of the recess is about 30 to 200 μm.

Further, the back material may be as shown in FIG. The backing material 4 shown in FIG. 3 includes a low acoustic impedance layer 52 (specific acoustic impedance Z is 8 × 10 ⁶ kg / m ² · s or less) and a high impedance layer 53 (specific acoustic impedance Z is 20 × 6 kg / m ² · s or more) are alternately stacked. With such a configuration, the reflected wave from the back surface of the back material 5 can be canceled by interference, and the influence of the reflected wave from the back surface can be reduced. The dimensions of the back member 5 shown in FIG. 3 are about 0.04 to 0.2 mm in thickness.

  The drive shaft 3 shown in FIG. 1 is formed of a hollow coil formed by spirally winding a wire. As the wire constituting the drive shaft 3, besides a flat plate having a horizontally long rectangular cross section as shown in FIG. 1, a substantially round bar having a cross section of a circle or an ellipse, or the like, is used. Can be used. Of these, as shown in the figure, a flat coil made of a flat wire is preferable because the thickness of the coil can be reduced and the outer diameter of the drive shaft 3 can be reduced. Although the illustrated drive shaft 3 is a single-layer coil, it may be a coil having two or more layers.

  As a constituent material of the drive shaft 3 (that is, a constituent material of the wire), for example, a stainless steel, a Ni-Ti-based alloy of substantially 49 to 58 atomic% Ni (remainder Ni), or one of the Ni-Ti-based alloys Ni-Ti-X-based alloy (X is Co, Fe, Mn, Cr, V, Al, Nb, Pb, B, etc.) in which a part is substituted with 0.01 to 2.0% X, substantially 38. Cu-Zn-based alloy of 5-41.5 wt% Zn (remainder Cu), Cu-Zn-X-based alloy in which a part of this alloy is substituted with 1-10 wt% X (X is Be, Si, Sn , Al), a superelastic alloy such as a Ni-Al-based alloy of substantially 36 to 38 atomic% Al (remainder Ni), a precipitation hardening stainless steel (particularly a semi-austenite-based PH stainless steel), and a maraging stainless steel Metal materials such as stainless steel and high tensile steel Etc. is used.

  Among them, a superelastic alloy such as a Ni-Ti alloy is particularly preferable. The superelastic alloy referred to here is generally called a shape memory alloy, and is superelastic at least at a living body temperature (around 37 ° C.) (almost returns to the original shape even after being deformed to a region where a normal metal causes permanent strain). Property).

  When the drive shaft 3 is a flat coil as shown in the drawing, the outer diameter is 0.9 mm or less, preferably about 0.2 to 0.3 mm, and the thickness is about 0.02 to 0.2 mm. , Preferably about 0.05 to 0.15 mm, and the coil width is about 0.05 to 0.3 mm, preferably about 0.07 to 0.2 mm.

  The connecting member 7 is attached to the tip of the drive shaft 3. As shown in FIG. 4, the connecting member 7 has a cylindrical shape having a slit 7a on a side surface. The base end of the connecting member 7 and its vicinity are inserted into the drive shaft 3 and fixed to the inner surface of the drive shaft 3 with an adhesive or the like, and the front end is connected to the base end of the back member 5 with an adhesive or the like. It is fixed. As a result, the ultrasonic transducer 2 is integrally connected to the drive shaft 3 together with the back member 5, and rotates or reciprocates with the rotation or reciprocation of the drive shaft 3. The ultrasonic vibrator 2 may be configured to be directly connected to the drive shaft 3 without using a connecting member as illustrated.

  As shown in FIGS. 2 and 3, each of the two electrodes 22 of the ultrasonic transducer 2 has a signal transmitter for transmitting a signal between the ultrasonic transducer 2 and a transmission / reception circuit 32 described later. Are electrically connected. As shown in FIG. 4, each of these signal lines 6 includes a conductor 6a and an insulator 6b that covers and electrically insulates the conductor 6a. , And one end of the conductor 22 a is connected to the other electrode 22. The signal line 6 enters the lumen of the drive shaft 3 through the slit 7a of the connecting member 7, and extends through the lumen to the inside of a connector 10 described later.

  The exterior shaft 4 is made of a polyimide resin, and is provided so as to cover the ultrasonic vibrator 2, the drive shaft 3, the back member 5, and the like. The outer diameter of the outer shaft 4 is 1 mm or less, preferably 0.4 mm or less, and the thickness is 50 μm or less, preferably about 20 to 40 μm. The minimum interval 1 is 100 μm or less, preferably about 10 to 50 μm.

  The outer shaft 4 configured as described above has a tensile strength of 0.5 kgf or more and a high flexibility not to be kinked even when the outer diameter of the bend is 10 mm or less, so that the drive shaft 3 rotates or reciprocates. Also, the sliding resistance when inserted into another catheter such as a treatment catheter is small (dynamic friction resistance 0.1 or less). Accordingly, it is possible to provide an ultrasonic catheter having an outer diameter of 1 mm or less, which is excellent in pushability and trackability, can obtain a stable ultrasonic image, and has excellent operability. Here, the bending outer diameter refers to an outer diameter that substantially does not generate a kink when deformed by an external force to a predetermined bending outer diameter, and returns to an almost original shape after removing the external force.

  As the polyimide resin constituting the exterior shaft 4, for example, a polyimide homopolymer and a polyimide such as a polyimide resin, a polyamide imide resin, a polyester imide resin, and a polyether imide resin are used as main components, and other polymer components are used. And the like. In addition, within such a range that does not impair the properties of such a polyimide-based resin, for example, an alloying agent, a compatibilizer, a stabilizer, various pigments or the like may be mixed, or other resin materials may be blended. No problem.

  In particular, for example, ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene, polyvinyl fluoride, vinylidene fluoride, hexafluoropropylene-tetrafluoroethylene copolymer, It is preferable to mix a fluorine-based resin such as trifluoroethylene-vinylidene fluoride copolymer and use this as a constituent material of the exterior shaft 4. By including the fluorine-based resin, the sliding resistance of the exterior shaft 4 can be further reduced.

  When the fluorine-based resin is mixed as described above, the mixing amount of the fluorine-based resin is preferably 5 to 30% by weight, more preferably 5 to 10% by weight of the polyimide resin. With such a ratio, the sliding resistance of the exterior shaft 4 is maintained without deteriorating the characteristics of the polyimide resin. The inner surface of the exterior shaft 4 is made of a low friction material such as silicone or polyethylene terephthalate (Teflon (registered trademark)). The outer shaft 4 can be thinly coated (about several μm) with a resin or a hydrophilic resin such as poly (2-hydroxyethyl methacrylate), polyhydroxyethyl acrylate, hydroxypropylcellulose, and methyl vinyl ether maleic anhydride copolymer. Can reduce the sliding resistance of the inner surface.

  The exterior shaft 4 can be formed, for example, by molding the above-mentioned polyimide resin by a wire coating method by melt extrusion, a dipping method, or the like.

  The exterior shaft 4 formed by using such a polyimide resin has a considerable strength (specifically, a tensile strength of about 1 kg) even if it has a thin thickness of about 50 μm, and has a sliding resistance. Can be reduced (dynamic friction resistance is 0.1 or less). Therefore, it is suitably used as an outer shaft of a small-diameter ultrasonic catheter having an outer diameter of 1 mm or less, a wall thickness of 50 μm or less, and a distance from the drive shaft 3 of 100 μm or less. The wall thickness of the exterior shaft 4 is 50 μm or less, preferably about 20 to 40 μm. When the thickness is within this range, the radial width of the drive shaft 3 and the ultrasonic transducer 2 can be sufficiently secured, and an ultrasonic catheter having an outer diameter of 1 mm or less can be suitably manufactured.

  The minimum distance l between the exterior shaft 4 and the drive shaft 3 is 100 μm or less, preferably about 10 to 50 μm. If the distance 1 exceeds 100 μm, the clearance (clearance) between the drive shaft 3 and the exterior shaft 4 is too large, and when the ultrasonic catheter 1 is bent along the shape of the body cavity at the time of insertion into the body cavity, the drive is performed. The shaft 3 is likely to be largely displaced in the radial direction within the exterior shaft 4, and it is difficult to accurately transmit a driving force from a mechanical drive source 31, which will be described later, to the ultrasonic vibrator 2, and it is difficult to obtain a stable ultrasonic image. In the case of the above spacing, a part of the drive shaft 3 may come into contact with the inner surface of the exterior shaft 4, but the exterior resistance of the exterior shaft 4 made of polyimide resin is small as described above. The rotation and reciprocation of the drive shaft 3 are not hindered.

  In the present invention, the “minimum distance” is the minimum distance (distance) between the entire drive shaft 3 and the exterior shaft (a signal outside the drive shaft, as in a reference example shown in FIG. 5 described later). In the case where the transmission body or the like is provided integrally, it means the minimum distance between the signal transmission body and the exterior shaft.

  A connector 10 is fixed to the base end of the exterior shaft 4. The connector 10 is configured to be detachably connected to an external device 30 described later.

  Two electrical contacts 11 and 12 are built in the connector 10. Then, the base end of the conductor 6a of one signal line 6 is electrically connected to the electric contact 11, and the base end of the conductor 6a of the other signal line 6 is electrically connected to the electric contact 12. I have.

  The external device 30 provided outside the body has a mechanical drive source 31, a transmission / reception circuit 32, and two electric contacts 33 and 34. When the connector 10 is connected to the external device 30, the electrical contact 33 contacts the electrical contact 11 on the ultrasound catheter 1 side, and the electrical contact 34 contacts the electrical contact 12 on the ultrasound catheter 1 side, and these are electrically connected. . Thereby, the electric signal from the transmission / reception circuit 32 is transmitted to the ultrasonic vibrator 2 via one of the signal lines 6, and the vibrator 2 transmits an ultrasonic wave of a predetermined wavelength and is reflected in the body cavity. The transmitted ultrasonic signal is transmitted to the transmission / reception circuit 32 via the other signal line 6. Further, the mechanical drive source 31 mechanically drives the drive shaft 3 to rotate or reciprocate the drive shaft 3. By this drive, a radial scan or a linear scan of the ultrasonic transducer 2 can be performed.

  Since the ultrasonic catheter of the present invention can be reduced in diameter, it can be used alone by inserting it into peripheral blood vessels and blood vessels such as the heart, brain, and lower limbs. It can be used by inserting it into the lumen of a treatment catheter such as a catheter for medical use, an atherectomy catheter or the like, and simultaneously or in parallel with the diagnosis in the body cavity using an ultrasonic catheter and the treatment with the above-mentioned treatment catheter.

  FIG. 5 is a partially enlarged longitudinal sectional view showing another reference example of the present invention. Hereinafter, the present embodiment will be described. However, the same components as those of the embodiment shown in FIG.

  The drive shaft 3 shown in FIG. 5 is formed in a solid rod shape. The drive shaft 3 integrally has, outside of the drive shaft 3, a signal line 6 which is a signal transmission body for transmitting a signal between the ultrasonic transducer 2 and the transmission / reception circuit. In the present embodiment, the signal lines 6 are spirally wound up to the base end of the drive shaft 3 so as not to overlap with each other. Accordingly, the signal line 6 forms a part of the drive shaft 3 and rotates or reciprocates with the signal line 6.

  The back member 5 is directly fixed to the tip of the drive shaft 3 with an adhesive or the like, whereby the ultrasonic vibrator 2 and the drive shaft 3 are integrally connected.

Such a rod-shaped drive shaft 3 is excellent in mechanical strength with a tensile strength of 20 kgf / mm ² or more, and has a bend outside diameter of at least about 50 cm or less from the distal end side of the ultrasonic catheter 1 at least about 5 cm or more. It is preferable that the material has such flexibility that it can be restored to its original shape after the bending stress is unloaded. This is a characteristic required at the time of insertion into small-diameter peripheral blood vessels or vessels such as the heart, brain, and lower limbs. Here, the bending outer diameter refers to an outer diameter that substantially does not generate a kink when deformed by an external force to a predetermined bending outer diameter, and returns to an almost original shape after removing the external force.

  As a constituent material of the drive shaft 3, for example, stainless steel, a Ni-Ti-based alloy of substantially 49 to 58 atomic% Ni (remaining Ti), and a part of the Ni-Ti-based alloy is 0.01 to 2 Ni-Ti-X-based alloy (X is Co, Fe, Mn, Cr, V, Al, Nb, Pb, B, etc.) substituted with 0.0% X, substantially 38.5 to 41.5% by weight Cu-Zn-based alloy of Zn (remainder Cu), Cu-Zn-X-based alloy (X is Be, Si, Sn, Al) in which a part of this alloy is substituted with 1 to 10% by weight X, substantially Superelastic alloys such as Ni-Al alloys of 36 to 38 atomic% Al (the balance being Ni), precipitation hardening stainless steels (PH stainless steels are particularly preferable, semi-austenite type), stainless steels such as maraging stainless steels, and high tensile strength A metal material such as steel is used. Among them, a superelastic alloy such as a Ni-Ti alloy is particularly preferable. The superelastic alloy referred to here is generally called a shape memory alloy, and is superelastic at least at a living body temperature (around 37 ° C.) (almost returns to the original shape even after being deformed to a region where a normal metal causes permanent strain). Property).

  In this embodiment, the outer diameter of the drive shaft 3 is about 0.1 to 0.75 mm, more preferably about 0.2 to 0.3 mm. The outer diameter of the signal line 6 is about 25 to 50 μm.

  In the present embodiment, the minimum distance l between the exterior shaft 4 and the signal line 6 integrally provided outside the drive shaft 3 is 100 μm or less. Thereby, similarly to the reference example shown in FIG. 1, the outer shaft 4 has high tensile strength and flexibility, and is inserted when the drive shaft 3 rotates or reciprocates, or inserted into another catheter such as a treatment catheter. And the sliding resistance when used. Accordingly, it is possible to provide an ultrasonic catheter having an outer diameter of 1 mm or less, which is excellent in pushability and trackability, can obtain a stable ultrasonic image, and has excellent operability.

  FIG. 6 is a partially enlarged longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. Hereinafter, the present embodiment will be described, but the same components as those of the embodiment shown in FIG.

  The ultrasonic catheter 1 shown in FIG. 6 is an ultrasonic catheter that is used by being inserted into a body cavity, and includes an ultrasonic vibrator 2 and an ultrasonic wave that reflects ultrasonic waves transmitted from the ultrasonic vibrator 2 into the body cavity. A drive shaft 3 that is provided on the base end side of the ultrasonic reflector 8 and that is provided on the base end side of the ultrasonic reflector 8 and that transmits a driving force from a drive source outside the body to the ultrasonic reflector 8 and rotates or reciprocates the ultrasonic reflector; , An ultrasonic vibrator 2, an ultrasonic reflector 8 and a hollow exterior shaft 4 enclosing the drive shaft 3. The exterior shaft 4 is made of a polyimide resin, has an outer diameter of 1 mm or less, and has a thickness of 1 mm or less. Is formed to 50 μm or less, and the minimum distance between the exterior shaft 4 and the drive shaft 3 is set to 100 μm or less.

  Specifically, the ultrasonic vibrator 2 and the backing member 5 are embedded in the exterior shaft 5, and are attached to the distal side member 14 b of the fixing member 14 extending from the base end side to the vicinity of the distal end of the ultrasonic catheter 1. The ultrasonic transducer 1 is fixed with an adhesive or the like with the back side (the back member 5 side) facing the tip of the ultrasonic catheter 1. The illustrated fixing member 14 includes a base member 14a and a base member 14a and a separate member 14b, but may be a single member.

  The drive shaft 3 has a solid rod shape, and an ultrasonic reflector 8 is fixed to an end of the drive shaft 3 with an adhesive or the like. The drive shaft 3 is rotatably supported by a bearing 13 built in the exterior shaft 4. The constituent materials, dimensions, and the like of the drive shaft 3 can be the same as those described in the reference example shown in FIG.

  The ultrasonic wave transmitted from the ultrasonic transducer 2 is reflected in the radial direction of the ultrasonic catheter 1 by the reflection surface 8a of the ultrasonic reflector 8. At the same time, the ultrasonic wave reflected in the body cavity is reflected by the reflection surface 8a of the ultrasonic reflector 8, and reaches the ultrasonic transducer 2. The drive shaft 3 is driven by an external mechanical drive source (not shown), makes a rotational movement, and the ultrasonic reflector 8 connected to the drive shaft 3 also rotates therewith. Thus, a radial scan can be performed at a desired position in a body cavity.

  In this embodiment, the radial scanning system is used. However, as described in the embodiment shown in FIG. 1, the bearing 13 is not provided, the reciprocating motion of the drive shaft 3 is enabled, and the linear scanning by the ultrasonic transducer 2 is performed. You can also do it.

  FIG. 7 is a partially enlarged longitudinal sectional view showing an embodiment of the present invention. In this embodiment, the exterior shaft 4 includes a base end portion 41 having an open front end, and a front end portion 42 joined to the open front end of the base end portion 41. Other configurations are the same as those shown in FIG.

  With this configuration, the long drive shaft 3 and other components are inserted into the base end portion 41 of the exterior shaft 4 and assembled, and then the front end portion 42 and the base end portion 41 are joined to each other, so that the ultrasonic The manufacture of the catheter 1 can be made easier. Further, the distal end portion 42 can be made of a material different from that of the base end portion 41. For this reason, for example, the tip portion 42 is formed of a material other than the polyimide resin, such as an olefin resin such as polyethylene or polypropylene, through which ultrasonic waves can easily pass, and a more stable ultrasonic image can be obtained. You can do so. Further, as shown in the figure, the boundary between the base end portion 41 and the front end portion 42 is set substantially in the vicinity of the ultrasonic vibrator 2, and the base end portion 41 is made of the above-mentioned polyimide resin by using, for example, tungsten powder, copper, gold, silver, , Formed by using a mixture of X-ray opaque materials such as platinum, and by forming the tip portion 42 from a material that does not contain the X-ray opaque member and that can transmit ultrasonic waves. The position of the ultrasonic transducer 2, that is, the measurement position of the ultrasonic wave in the body cavity by the ultrasonic wave can be made visible under X-ray fluoroscopy.

  FIG. 8 is a partially enlarged longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. In this reference example, a spiral groove 43 is formed at the tip of the exterior shaft 4. By doing so, the flexibility of the exterior shaft 4 can be improved, and the flexibility (flexibility) of the ultrasonic catheter 1 can be improved.

  The grooves 43 can be formed by subjecting the exterior shaft 4 to, for example, laser processing, dicing saw processing, or the like.

  Further, it is preferable that the pitch of the grooves 43 is narrowed toward the distal end of the catheter as shown in the figure. In this way, the outer shaft 4 can be made more flexible as it is closer to the distal end of the ultrasonic catheter 1, and the flexibility of the ultrasonic catheter 1 can be further improved. Therefore, the operability of the ultrasonic catheter 1 is further improved, and the risk of damage to the blood vessel wall due to the catheter tip is reduced, and the ultrasonic catheter 1 can safely travel in the blood vessel.

  When the pitch of the groove 43 is thus changed, the pitch is preferably about 0.05 to 0.2 mm on the distal end side of the groove 43 and about 1.0 to 40.0 mm on the proximal end side. When the pitch of the grooves 43 is constant, it is preferable that the pitch is about 0.5 to 5 mm. Further, it is preferable that the length of the portion of the exterior shaft 4 where the groove 43 is formed be about 50 to 300 mm.

  In the illustrated example, the groove 43 has a single spiral shape, but is not limited thereto and may have two or more grooves.

  In addition, the outer diameter of the exterior shaft 4 of the present reference example gradually decreases from the position separated from the tip by a predetermined length toward the tip. By doing so, the flexibility (flexibility) of the ultrasonic catheter 1 can be improved in combination with the groove 43.

  FIG. 9 is a partially enlarged longitudinal sectional view showing another reference example of the present invention. In the present reference example, a guide member 15 for facilitating introduction of the ultrasonic catheter 1 into a body cavity is provided at a distal end of the exterior shaft 4, and other configurations are the same as those in FIG.

  In the present embodiment, the guide member 15 is constituted by a coil spring 16 fixed to the tip of the exterior shaft 4. With this guide member 15, damage to the body cavity due to the distal end portion of the ultrasonic catheter 1 is reduced, and the ultrasonic catheter 1 can safely travel in the body cavity.

  In addition, by providing such a guide member 15, as shown in FIG. 10, the ultrasonic catheter 1 can be used as a treatment catheter 70 (in the illustrated example, a blood vessel forming balloon having a balloon 71 for expanding a stenotic portion of a blood vessel 60). When the ultrasonic catheter 1 is used by inserting it into the lumen 72 of the balloon catheter 70), the treatment catheter 70 can be inserted into the body cavity along the ultrasonic catheter 1. Therefore, it is not necessary to prepare a guide wire for guiding the treatment catheter 70 separately from the ultrasonic catheter 1 when inserting the treatment catheter 70 into the body cavity, and the operability of the ultrasonic catheter 1 and the treatment catheter 70 is improved. .

  It is preferable that the outer diameter of the guide member 15 is gradually reduced toward the distal end as shown in the figure. Thereby, the flexibility of the guide member 15 can be further improved.

  As a constituent material of the coil spring 16 forming the guide member 15, for example, stainless steel, a Ni-Ti-based alloy of substantially 49 to 58 atomic% Ni (remaining Ni), or a part of the Ni-Ti-based alloy is used. Ni-Ti-X-based alloy (X is Co, Fe, Mn, Cr, V, Al, Nb, Pb, B, etc.) substituted with 0.01 to 2.0% X, substantially 38.5 to 38.5% Cu-Zn-based alloy of 41.5 wt% Zn (remainder Cu), Cu-Zn-X-based alloy in which a part of this alloy is substituted with 1 to 10 wt% X (X is Be, Si, Sn, Al ), Superelastic alloys such as Ni-Al alloys of substantially 36 to 38 atomic% Al (remainder Ni), precipitation hardening stainless steels (PH stainless steels are particularly preferred, semi-austenitic alloys), maraging stainless steels and the like. Metal materials such as stainless steel and high tensile steel, Rui, Pt, Pt alloy, W, W alloy, Ag, an X-ray opaque material such as Ag alloy is used.

  When an X-ray opaque material such as Pt, Pt alloy, W, W alloy, Ag, or Ag alloy is used, the tip position of the ultrasound catheter 1 can be changed under X-ray fluoroscopy by the guide member 15 which is also the tip. You can easily confirm. Further, when the coil spring 16 is formed of a superelastic alloy such as the above-mentioned Ni-Ti alloy, the guide member 15 can be made more flexible.

The outer diameter of the coil spring 16 is preferably about 0.2 to 0.6 mm on the distal side and about 0.3 to 1.0 mm on the proximal side when the outer diameter is changed as shown in the figure. When the outer diameter is constant, it is preferably about 0.3 to 0.5 mm. The length of the coil spring 16 is preferably about 10 to 50 mm. When the coil spring 16 is made of the above superelastic alloy, the buckling strength (yield stress under load) is 5 to 200 kg / mm ² (22 ° C.), more preferably 8 to 150 kg / mm ² , The restoration stress (yield stress at the time of unloading) is 3 to 180 kg / mm ² (22 ° C.), and more preferably 5 to 150 kg / mm ² .

  The coil spring 16 may have a bent shape, and a desired blood vessel may be selected and a function of selecting a blood vessel that can guide the ultrasonic catheter 1 to the desired blood vessel may be added (not shown).

  Further, in order to further reduce the risk of damage in the body cavity due to the distal end of the guide member 15, a distal end member 17 may be attached as shown in FIG. The tip member 17 is formed in a head piece shape having a smooth convex curved surface. As the tip member 17, for example, a material obtained by heating and melting an extremely fine metal wire to form a smooth convex curved surface, or a material obtained by processing a brazing material into a spherical shape is used.

  Further, a support rod 171 is fixed to the base end of the distal end member 17. The support rod 171 extends to the proximal side through the inside of the coil spring 16, and the proximal end is fixed to the exterior shaft 4 via the adhesive 9. Thereby, the tip member 17 is fixed to the tip of the guide member 15. With this support rod 171, kink resistance and tensile strength near the distal end of the ultrasonic catheter 1 can be improved.

  As the constituent material of the support rod 171, the same material as the constituent material of the coil spring 16 can be used. Further, the cross section of the support rod 171 may be any shape such as a circle, an ellipse, and a rectangle. Further, the support rod 171 and the tip member 17 can be integrated.

  Further, as the fixing agent 9, brazing materials and various adhesives can be suitably used.

  The guide member 15 may be configured as shown in FIG. In the reference example shown in FIG. 12, the guide member 15 is configured by a wire 18 formed of a superelastic alloy such as the above-mentioned Ni-Ti alloy. Even with such a guide member 15, similarly to the reference example shown in FIG. 9, damage to the body cavity due to the distal end portion of the ultrasonic catheter 1 is reduced, and the ultrasonic catheter 1 can safely travel in the body cavity.

The wire 18 preferably has an outer diameter of about 0.3 to 1.0 mm and a length of about 10 to 50 mm. The buckling strength (yield stress under load) is 5 to 200 kg / mm ² (22 ° C.). More preferably, it is 8 to 150 kg / mm ² , and the restoring stress (yield stress at the time of unloading) is 3 to 180 kg / mm ² (22 ° C.), more preferably 5 to 150 kg / mm ² .

  Further, the illustrated wire 18 has a bent shape at its distal end side, and has a blood vessel selectivity function that can select a desired blood vessel and guide the ultrasonic catheter 1 to the blood vessel at a branch point of the blood vessel. I have.

  FIG. 13 is a partially enlarged longitudinal sectional view showing another reference example of the present invention. In the present reference example, a member capable of X-ray imaging is provided on the distal end side of the ultrasonic catheter 1.

  Specifically, the reference example shown in FIG. 13 has substantially the same configuration as that of the reference example shown in FIG. 12, but a marker 19 capable of X-ray imaging is embedded near the tip of the rod 15. This makes it possible to easily confirm the position of the ultrasonic catheter 1 in the body cavity under fluoroscopy.

  As the material of the marker 19, the X-ray opaque material exemplified as the constituent material of the coil spring 13 is preferably used.

  The structure for providing a member capable of performing X-ray imaging on the distal end side of the ultrasonic catheter 1 is not limited to the configuration shown in FIG. 13. For example, as described above in the reference example shown in FIG. It is also possible to form the coil spring 16 from an X-ray opaque material, and to use the coil spring 16 as a member capable of X-ray imaging.

  It can be inserted into a coronary artery or other small blood vessels of the heart, or a blood vessel such as a bile duct, and used as an ultrasonic catheter for displaying a lumen cross-sectional image or measuring blood flow.

It is a partial cross-section whole side view which shows one reference example of the ultrasonic catheter of this invention. FIG. 2 is an enlarged longitudinal sectional view showing the ultrasonic transducer and a backing member of the reference example shown in FIG. 1. It is an expanded longitudinal cross-sectional view which shows the modification of a back material. FIG. 4 is an end view taken along line IV-IV in FIG. 1. FIG. 6 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. FIG. 6 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a partial cross-section whole side view which shows the Example of the ultrasonic catheter of this invention. FIG. 9 is a partial cross-sectional side view showing another reference example of the ultrasonic catheter of the present invention. FIG. 6 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. It is explanatory drawing which shows the example of application of the ultrasonic catheter of this invention. FIG. 6 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. FIG. 6 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention. FIG. 9 is a partial longitudinal sectional view showing another reference example of the ultrasonic catheter of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Ultrasonic catheter 2 Ultrasonic transducer 3 Drive shaft 4 Exterior shaft 6 Signal line 43 Groove 8 Ultrasonic reflector 31 Mechanical drive source 32 Transmission / reception circuit 15 Guide member 16 Coil spring 18 Wire 19 X-ray contrast marker l Minimum interval

Claims (5)

An ultrasonic catheter used by being inserted into a body cavity, the ultrasonic catheter being provided at a base end side of the ultrasonic transducer and transmitting a driving force from a driving source outside the body to the ultrasonic transducer. A drive shaft for rotating or reciprocating the ultrasonic vibrator, and a hollow exterior shaft enclosing the ultrasonic vibrator and the drive shaft, and the exterior shaft is formed using a polyimide resin. And a distal end joined to the proximal end and formed of an ultrasonic-permeable material other than the polyimide-based resin. An ultrasonic catheter, which passes through a sound-permeable material. The ultrasonic catheter according to claim 1, wherein a boundary between the proximal end and the distal end of the exterior shaft is located near the ultrasonic transducer. The ultrasonic catheter according to claim 1, wherein the ultrasonic-permeable material is an olefin-based resin. The ultrasonic catheter according to claim 3, wherein the olefin-based resin is polyethylene or polypropylene. The ultrasonic catheter according to any one of claims 1 to 4, wherein the polyimide-based resin contains 5 to 30% of a fluorine-based resin.

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