Guide wire

Abstract

To provide a guide wire in which a housing of a sensor is easy to bend and a slit is hard to break.SOLUTION: A guide wire 30 includes: a core wire 31; a first spiral body 33; a second spiral body 35; a housing 34 attached to the first spiral body 33 and the second spiral body 35; and a pressure sensor 11 located in an internal space of the housing 34. The housing 34 has slits 51 to 54 spirally extending while penetrating a peripheral wall 42. The slit 51 has: a center portion 55 spirally extending in an extension direction Ds; and an end portion 56 bent along a bending direction De with respect to the center portion 55.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a guide wire having a sensor and inserted into a blood vessel. [Background technology]

[0002] In order to detect various physical quantities in a blood vessel, such as blood pressure and blood flow, a guide wire equipped with a sensor is inserted into the blood vessel. The guide wire is inserted into a vein, for example, from below the collarbone or from the thigh, and its tip is advanced to a coronary artery. Then, the blood pressure and other parameters in the coronary artery are measured by a sensor provided at the tip of the guide wire (Patent Document 1).

[0003] The sensor is located in the internal space of a cylindrical housing that constitutes part of the guidewire. For example, a metal housing is highly rigid and therefore suitable for protecting the sensor, but it is difficult to bend along the curve of a blood vessel. As a result, there is a problem that it is difficult to pass the housing through the curved portion of the blood vessel. To address this problem, Patent Documents 2 and 3 disclose configurations in which slits are formed in the housing to make it easier to bend. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-225312 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-147459 [Patent Document 3] Patent No. 6395826 Summary of the Invention [Problem to be solved by the invention]

[0005] Although a housing having a slit formed therein is easily bent, the slit deforms when bent, and the ends of the slit are easily broken. Furthermore, when a tensile force is applied to the housing, the ends of the slit are also easily broken. On the other hand, as disclosed in Patent Documents 2 and 3, if the length of the slit in the extension direction is made relatively short, the strength of the slit increases, but the housing becomes less likely to bend or stretch, and operability is impaired.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a guide wire in which the sensor housing is easily bent and the slit is not easily broken. [Means for solving the problem]

[0007] (1) A guidewire according to the present invention comprises a wire, a cylindrical housing attached to the wire, and a sensor located within the interior space of the housing. The housing has a slit extending spirally through a peripheral wall of the housing. The slit has a central portion extending spirally in a fixed extension direction along the peripheral wall, and an end portion including one end of the slit, which intersects the extension direction and is bent relative to the central portion along a bending direction in which the spiral pitch increases.

[0008] The slits allow the housing to bend and stretch easily, and the end portions of the slits make the end portions less likely to break even when a tensile force is applied to the housing.

[0009] (2) Preferably, the bending direction is parallel to the axis of the housing.

[0010] (3) Preferably, the end portion is curved in a U-shape.

[0011] (4) Preferably, the bent portions between the central portion and the end portions are rounded.

[0012] (5) Preferably, the spiral pitch at the central portion of the first slit is larger at both ends than at the center.

[0013] In the central portion of the first slit, both end sides are more likely to withstand tension, and the center is more likely to stretch in the axial direction.

[0014] (6) Preferably, the housing further has a second slit extending spirally through the peripheral wall of the housing, and the first slit and the second slit form a double spiral that are alternately positioned in the axial direction of the housing.

[0015] The double spiral makes the housing more flexible.

[0016] (7) Preferably, the housing has an internal space surrounded by a peripheral wall where the slit is located, and the internal space is filled with a synthetic resin.

[0017] Since the tensile force acting on the housing also acts on the synthetic resin, the tensile strength of the housing and the synthetic resin as a whole is improved.

[0018] (8) A guidewire according to the present invention comprises a wire, a cylindrical housing attached to the wire, and a sensor located in an internal space of the housing. The housing has a slit extending in a spiral shape penetrating a peripheral wall of the housing. The internal space of the housing, surrounded by the peripheral wall where the slit is located, is filled with a synthetic resin.

[0019] Since the tensile force acting on the housing also acts on the synthetic resin, the tensile strength of the housing and the synthetic resin as a whole is improved. [Effects of the Invention]

[0020] According to the present invention, the housing of the sensor is easily bent and the slit is not easily broken. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of a guidewire system 10. [Figure 2] FIG. 2 is a diagram showing a guidewire 30. As shown in FIG. [Figure 3] FIG. 3 is a perspective view of the pressure sensor 11. [Figure 4] FIG. 4 is a cross-sectional view showing the internal configuration of the housing 34. [Figure 5] FIG. 5 is a diagram showing the slits 51-54. [Figure 6] FIG. 6 is a partially enlarged view of FIG. [Figure 7] FIG. 7 is an enlarged view showing a slit 51 according to a modified example. [Figure 8] FIG. 8 is an enlarged view showing a slit 51 according to a modified example. [Figure 9] FIG. 9 is a view showing a housing 34 according to a modified example. [Figure 10] FIG. 10 is a view showing a housing 34 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0022] Preferred embodiments of the present invention will be described below. It should be noted that each embodiment is merely one example of the present invention, and it goes without saying that the example can be modified without departing from the spirit and scope of the present invention.

[0023] [Guidewire System 10] 1, the guidewire system 10 includes a guidewire 30, a computing device 20, and a female connector 40 that connects the guidewire 30 and the computing device 20. The guidewire 30 is a long, thin cord that can be inserted into a blood vessel such as a coronary artery. The guidewire 30 includes, at its distal end, a pressure sensor 11 (see FIG. 3, an example of a sensor) that outputs electrical information in response to the pressure within the blood vessel.

[0024] The computing device 20 includes a power supply unit 21 that supplies current to the pressure sensor 11 of the guidewire 30, a computing unit 22 that processes electrical information output from the pressure sensor 11, and a memory 23 that stores information necessary for the computing process. The electrical information output from the pressure sensor 11 is transmitted from the guidewire 30 to the computing unit 22 via the female connector 40 and cable 24. The computing unit 22 calculates blood pressure based on the electrical information output from the pressure sensor 11. In other words, the guidewire system 10 is used to measure blood pressure.

[0025] 1, of the two ends of guidewire 30, the fixed end (the end connected to female connector 40) is the proximal end (the end on the lower left side in FIG. 1), and the free end (the tip when inserted into a blood vessel) is the distal end (the end on the upper left side in FIG. 1). In this specification, the side of guidewire 30 where the proximal end is located is referred to as the proximal end side, and the side where the distal end is located is referred to as the distal end side.

[0026] [Guidewire 30] FIG. 2 shows a guidewire 30. In FIG. 2, the left side is the distal end side of the guidewire 30, and the right side is the proximal end side of the guidewire 30. The guidewire 30 is broadly divided into a tip portion 30A (an example of a distal end portion), a core wire 31 (an example of a main body), and a male connector 39 (an example of a connector). The tip portion 30A has a tip guide section 32, a first helix 33, a housing 34, and a second helix 35. Note that the axis 50 refers to the axis of the guidewire 30 when the guidewire 30 is in a straight state without being bent or curved.

[0027] The core wire 31 is a cylindrical member, such as a solid stainless steel member. The tip guide portion 32 is a hemispherical member located at the distal end that is convex toward the distal end and contacts the blood vessel wall to guide the guide wire 30 along the blood vessel. The first helix 33 and the second helix 35 are wire members wound in a helical shape and are configured to be more flexible than the core wire 31 so that the distal end of the guide wire 30 can easily follow the blood vessel.

[0028] The housing 34 is a housing that houses the pressure sensor 11 in its internal space. The housing 34 has a cylindrical shape. The housing 34 has two through holes 41. The two through holes 41 are arranged 180° symmetrically about the axis 50, and only one of the through holes 41 is visible in FIG. 2. Blood enters the housing 34 through the through hole 41 and comes into contact with the diaphragm 13 (FIG. 3) of the pressure sensor 11. The housing 34 has slits 51, 52, 53, and 54. The slits 51, 52, 53, and 54 will be described in detail later.

[0029] A tapered pin 38 (see FIG. 3 ) extends from the distal end of the core wire 31 toward the housing 34 through the internal space of the second helix 35. The tapered pin 38 is a member that reinforces the bending rigidity of the second helix 35. The tapered pin 38 is cylindrical, and its outer diameter gradually decreases from the distal end of the core wire 31 toward the housing 34. Although not shown in the drawings, a tip guide pin extends from the distal end of the housing 34 toward the tip guide portion 32 through the internal space of the first helix 33. The tip guide pin is cylindrical and a member that reinforces the bending rigidity of the first helix 33. The tip guide pin is fixed to the housing 34 and the tip guide portion 32. A male connector 39 is provided at the proximal end of the core wire 31. The male connector 39 is inserted into a female connector 40, thereby electrically connecting the pressure sensor 11 and the computing device 20. The core wire 31, the first spiral 33, and the second spiral 35 are examples of wire materials.

[0030] As shown in FIG. 3, the pressure sensor 11 includes a sensor body 12, a diaphragm 13, a bridge circuit 14, four conductive wires 15, and a connecting portion 16. The sensor body 12 is fixed to a tapered pin 38, which is fixed to a core wire 31, by the connecting portion 16, which is made of, for example, an adhesive. The diaphragm 13, the bridge circuit 14, and the four conductive wires 15 are attached to the sensor body 12. The bridge circuit 14 is a full-bridge circuit in which all four resistors 17 function as strain gauges for measurement. The bridge circuit 14 includes four resistors 17, four terminals 18A and 18B, and four connecting portions 19. The four resistors 17 are fixed to the diaphragm 13. The four terminals 18A and 18B consist of two input terminals 18A and two output terminals 18B. Each connecting element 19 electrically connects each resistor 17 to each terminal 18A, 18B. Each conductive wire 15 is electrically connected to each terminal 18A, 18B, extends through the internal space of the core wire 31 toward the base end, and is electrically connected to each connecting terminal of the male connector 39.

[0031] When the guide wire 30 is inserted into a blood vessel and blood pressure is applied to the pressure sensor 11, the diaphragm 13 elastically deforms in response to the blood pressure. As the diaphragm 13 elastically deforms, the four resistors 17 also elastically deform, changing the electrical resistance values of the four resistors 17. In this state, when a voltage is applied between the two input terminals 18A, a potential difference is generated between the two output terminals 18B. Based on this potential difference, the blood pressure is calculated by the calculation device 20 (FIG. 1).

[0032] As shown in Fig. 4, the pressure sensor 11 is located in the internal space of the housing 34, closer to the proximal end than the through-hole 41. In the housing 34, the internal space closer to the proximal end than the sensor body 12 of the pressure sensor 11 is filled with a synthetic resin 43. The internal space of the housing 34 is also filled with synthetic resin 43 on the distal end side than the through-hole 41. Slits 51 to 54, which will be described later, are located in the peripheral wall 42 of the housing 34, which defines the internal space filled with the synthetic resin 43. The synthetic resin 43 is, for example, an epoxy resin, a urethane resin, or a polyamide elastomer resin.

[0033] [Slits 51, 52] As shown in FIG. 5, slits 51 to 54 are formed in the housing 34. Each of the slits 51 to 54 penetrates the peripheral wall 42 of the housing 34. The slits 51 to 54 extend in a spiral shape centered on the axis 50 of the housing 34. As shown in FIG. 6, when the housing 34 is viewed from a direction perpendicular to the axis 50, the angle θ1 formed by the intersection of the extension direction Ds of each of the slits 51 to 54 and the axis 50 is constant and is approximately 60° in this embodiment. The extension directions Ds of the slits 51 to 54 are parallel to each other. In this embodiment, when the housing 34 is viewed from the proximal end to the distal end along the axis 50, the slits 51 to 54 each extend clockwise while rotating toward the distal end.

[0034] As shown in FIG. 5 , slits 51 and 52 are located proximally relative to through-hole 41 in housing 34. Slits 53 and 54 are located distally relative to through-hole 41 in housing 34. Slits 51 and 52 form a double spiral that is alternately positioned with respect to axis 50 of housing 34. In other words, slits 51 and 52 are out of phase with each other by half a period around axis 50. In further other words, slit 52 is located at a position that differs by half the distance that slit 51 travels along axis 50 in one rotation around axis 50. Slits 53 and 54 also form a double spiral like slits 51 and 52.

[0035] 6, the slit 51 has a central portion 55 that forms a constant included angle θ1 with respect to the axis 50, and end portions 56 located on both sides of the axis 50 with respect to the central portion 55. In this embodiment, the two end portions 56 are located symmetrically at 180° with respect to the axis 50, and therefore the end portion 56 located on the distal end side is indicated by a dashed line in FIG. 5. The two end portions 56 are symmetrical in their positions with respect to the axis 50 and in their extending directions, but other than that, their positional relationships with respect to the central portion 55 are the same, and therefore, hereinafter, a detailed description will be given using the end portion 56 located on the proximal end side as an example.

[0036] As shown in FIG. 6 , the central portion 55 extends in a constant spiral in the extension direction Ds. The end portion 56 is continuous with the proximal end of the central portion 55. The end portion 56 constitutes one end of the slit 51. A large portion of the end portion 56 is aligned with a bending direction De that intersects with the extension direction Ds. In this embodiment, the bending direction De is parallel to the axis 50. A connection point 57 between the central portion 55 and the end portion 56 forms a smoothly curved R-shape. A large portion of the end portion 56 extending toward the proximal end is linear, and this linear portion is aligned with the bending direction De. Due to the end portion 56, the spiral pitch at the proximal end of the slit 51 increases toward the proximal end.

[0037] Although detailed description will be omitted, the slit 53 has a central portion and end portions similar to the slit 51. Furthermore, in this embodiment, the slits 52 and 54 do not have end portions 56 at both ends like the slit 51, and extend along the extension direction Ds over their entire range.

[0038] [Effects of this embodiment] According to the guide wire 30 according to the embodiment described above, the slits 51 to 54 are formed in the housing 34, which makes the housing 34 more easily bendable and stretchable along the axis 50. Furthermore, the formed slit 51 has a central portion 55 and an end portion 56, so that the end portion 56 is less likely to break even when a tensile force acts on the housing 34 along the axis 50.

[0039] Furthermore, since the internal space of the housing 34 surrounded by the peripheral wall 42 where the slits 51 to 54 are located is filled with synthetic resin 43, the tensile force acting along the axis 50 of the housing 34 also acts on the synthetic resin 43, improving the tensile strength of the housing 34 and the synthetic resin 43 as a whole.

[0040] [Variations] In the embodiment described above, the bending direction De in which the end portion 56 extends is along the axis 50, but the bending direction De does not have to be along the axis 50. For example, as shown in Fig. 7, the included angle θ2 formed by the end portion 56 and the axis 50 may be 15°, 30°, 45°, etc. Also, as shown in Fig. 8, the end portion 56 may be curved in a U-shape from the central portion 55 and extend in a so-called opposite direction.

[0041] Furthermore, in the embodiment described above, slits 51, 53 have end portions 56, but as shown in Fig. 9, slits 51, 53 may have only central portion 55 without end portions 56. In this embodiment, synthetic resin 43 is filled in the internal space surrounded by peripheral wall 42 in which slits 51 to 54 are located in housing 34, thereby improving the tensile strength of housing 34.

[0042] Furthermore, in the above-described embodiment, the slits 51, 52 and the slits 53, 54 form a double spiral, but the slits 52 and 54 may not be provided, and the slits 51 and 53 may be formed in the housing 34 as a single spiral. Furthermore, the pitch of the slits 51 does not have to be constant. For example, as shown in FIG. 10 , the slits 51 are formed in the housing 34 as a single spiral, and the spiral pitch of the central portion 55 of the slits 51 (the distance along the axis 50 of adjacent slits 51) may be such that the pitch P1 on both ends is greater than the pitch P2 in the center (P1>P2).

[0043] The smaller the spiral pitch of slit 51, the easier it is for housing 34 to stretch along axis 50, while the larger the pitch, the greater the tensile strength along axis 50. When a tensile force acts on housing 34 along axis 50, the center of central portion 55 of slit 51, which has a smaller pitch (P2), stretches more than the ends, which have a larger pitch (P1). As central portion 55 of slit 51 stretches along axis 50, the tensile length (stroke) until housing 34 breaks increases.

[0044] When central portion 55 of slit 51 is stretched to its full length at both the center and both ends and the tensile strength of both ends of central portion 55 is finally exceeded, housing 34 will break near the boundary between central portion 55 and end portion 56 (near both ends of central portion 55). Therefore, by reducing pitch P2 at the center of central portion 55 of slit 51, slit 51 can be more easily stretched along axis 50, increasing the stroke required for housing 34 to break; on the other hand, by increasing pitch P1 at both ends of central portion 55 of slit 51, the tensile force that can be withstood before breaking can be increased.

[0045] Furthermore, the pressure sensor 11 provided on the guidewire 30 is merely one example of a sensor, and other sensors or electronic circuits for measuring physical quantities of blood or blood vessels other than pressure (such as temperature or flow velocity) may be provided. Furthermore, the configuration of the distal end side of the guidewire 30 shown in the above-described embodiment is merely one example, and it goes without saying that the configurations of the helix, tapered pin, housing, etc. may be changed as appropriate. [Example]

[0046] [Examples 1-5] The housing was a stainless steel (SUS304) circular tube with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm. The slit width was 0.02 mm, the narrow angle θ1 between the axis and the single spiral slit was 60°, and the narrow angle θ2 between the axis and the direction in which the end of the slit extended was 15°, 30°, or 45°. One with an end parallel to the axis, and one with an end curved in a U-shape (see Figure 8) were formed, and these were designated Examples 1-5.

[0047] [Examples 6-8] The housing was a stainless steel (SUS304) circular tube with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm. The slit width was 0.02 mm, and the end portions of the single spiral slit extended parallel to the axis, with R at the boundary between the central portion and the end portion being 0.05, 0.3, and 0.4, respectively. These were designated Examples 6-8.

[0048] [Comparative Example] A comparative example was created using a stainless steel (SUS304) circular tube with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm as the housing, with a slit width of 0.02 mm and a single spiral slit with no end portion and an axis.

[0049] [Tensile strength] Using simulation software, in order to stabilize the shape of the spiral slit portion during tension, a wire rod with a diameter of 0.08 mm was inserted into the housing, and one end of the housing of each example and comparative example was fixed while the other end was tensioned to determine the tensile strength. The material properties of SU S304 were set to Young's modulus 200 GPa, Poisson's ratio 0.3, yield stress 250 MPa, and tangent modulus 1450 MPa. The results are shown in Table 1.

[0050] [Table 1]

[0051] As is clear from Table 1, the tensile strength of all Examples 1-8 was improved compared to the comparative example. In Examples 1-5, the tensile strength increased as the narrow angle θ1 increased. Furthermore, Example 4, in which the direction in which the end portions of the slits extended was parallel to the axis, showed the strongest results. In Examples 6-8, the tensile strength increased as R increased.

[0052] [Examples 9-12] The housing was a stainless steel (SUS304) circular tube with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm. The slit width was 0.02 mm, and the axis and the end portions of the single spiral slit extended parallel to the axis of the housing. The single spiral slit pitch (the length between adjacent slits along the axial direction of the circular tube) for a total length of 7 mm was 100 μm, 150 μm, 200 μm, or 280 μm. These were designated Examples 9-12, respectively.

[0053] Using the same simulation software as described above, tensile strength tests were conducted on Examples 9 to 12. The stroke length (mm) and tensile strength (N) at break are shown in Table 2. Note that Example 9 did not reach the maximum equivalent stress required for breakage even when the stroke length reached 15 mm.

[0054] [Table 2]

[0055] As is clear from Table 2, the larger the slit pitch, the shorter the stroke length and the higher the tensile strength. This means that as the slit pitch increases, the slit portion becomes less stretchable, but the tensile strength increases. [Explanation of symbols]

[0056] 11. Pressure sensor (sensor) 30 Guidewire 31 Core wire (wire rod) 33...1st helix (wire rod) 34. Housing 35...Second helix (wire rod) 42...peripheral wall 43. Synthetic resin 51~54 Slits 55...Central part 56...end part

Claims

1. A wire rod, a cylindrical housing attached to the wire; a sensor located in the interior space of the housing, The housing has a first slit extending spirally through a peripheral wall of the housing, The guide wire has an internal space surrounded by a peripheral wall in which the first slit is located in the housing, and is filled with a synthetic resin.

2. The first slit is a central portion extending spirally in a fixed extension direction along the peripheral wall; The guide wire according to claim 1, further comprising an end portion including one end of the first slit, which is bent relative to the central portion along a bending direction that intersects the extension direction and increases the spiral pitch.

3. 3. The guide wire according to claim 2, wherein the bending direction is parallel to the axis of the housing.

4. 3. The guidewire of claim 2, wherein said end portion is curved in a U-shape.

5. 5. The guide wire according to claim 2, wherein the bent portions between the central portion and the end portions are rounded.

6. 6. The guide wire according to claim 2, wherein the spiral pitch in the central portion of the first slit is larger on both ends than in the center.

7. The housing further has a second slit extending spirally through the peripheral wall of the housing, 7. The guide wire according to claim 1, wherein the first slits and the second slits form a double spiral that is alternately positioned with respect to the axial direction of the housing.

Images