Guide wire
The guide wire's spirally slitted housing with resin reinforcement addresses bending and tensile strength issues, ensuring flexibility and durability for navigating blood vessels.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NIPRO CORP
- Filing Date
- 2025-06-11
- Publication Date
- 2026-07-22
AI Technical Summary
Existing guide wires with sensor housings face challenges in bending through curved blood vessels due to rigidity issues, and slits in the housing can either deform or break under tension, compromising flexibility and strength.
A guide wire design featuring a cylindrical housing with spirally extending slits, including a central portion and end portions that intersect the extension direction, and optionally filled with synthetic resin, enhances flexibility and tensile strength.
The design allows for easier bending and reduced likelihood of slit breakage, while maintaining or improving tensile strength through the use of synthetic resin reinforcement.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a guide wire having a sensor and inserted into a blood vessel.
Background Art
[0002] In order to detect various physical quantities in a blood vessel, such as blood pressure and blood flow rate, a guide wire having a sensor is inserted into the blood vessel. The guide wire is inserted, for example, into a vein from below the collarbone or the thigh, and its tip is sent to the coronary artery. Then, blood pressure and the like 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 forms part of the guide wire. For example, a metal housing is suitable for protecting the sensor because it has high rigidity, but it is difficult to bend along the curvature of the 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. In response to this problem, configurations in which slits are formed in the housing to make the housing easier to bend are disclosed in Patent Documents 2 and 3.
Prior Art Documents
Patent Documents
[0006] The present invention has been made in view of the circumstances described above, and its purpose is to provide a guide wire in which the sensor housing is easily bent and the slit is less likely to break. [Means for solving the problem]
[0007] (1) The guide wire according to the present invention comprises a wire, a cylindrical housing attached to the wire, and a sensor located in the internal space of the housing. The housing has a slit that extends spirally through the peripheral wall of the housing. The slit has a central portion that extends spirally in a certain direction of extension along the peripheral wall, and an end portion that includes one end of the slit and is bent relative to the central portion along a bending direction that intersects the extension direction and increases the pitch of the spiral.
[0008] The slits make the housing more flexible and easier to stretch. The edges of the slits make it less likely for the housing to break even when tensile forces are applied to it.
[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 bend between the central portion and the end portion is R-shaped.
[0012] (5) Preferably, the spiral pitch in the central portion of the first slit is greater at both ends than at the center.
[0013] In the central portion of the first slit, both ends become more resistant to tension, while the center becomes more easily stretched in the axial direction.
[0014] (6) Preferably, the housing further has a second slit that extends spirally through the peripheral wall of the housing, and the first slit and the second slit form a double spiral that are alternately located with respect to the axial direction of the housing.
[0015] The double spiral design makes the housing more flexible.
[0016] (7) Preferably, the internal space surrounded by the peripheral wall in which the slit is located in the housing is filled with synthetic resin.
[0017] Since the tensile force acting on the housing also acts on the synthetic resin, the overall tensile strength of the housing and synthetic resin is improved.
[0018] (8) The guide wire according to the present invention comprises a wire, a cylindrical housing attached to the wire, and a sensor located in the internal space of the housing. The housing has a slit that extends spirally through the peripheral wall of the housing. The internal space of the housing surrounded by the peripheral wall where the slit is located is filled with synthetic resin.
[0019] Since the tensile force acting on the housing also acts on the synthetic resin, the overall tensile strength of the housing and synthetic resin is improved. [Effects of the Invention]
[0020] According to the present invention, the sensor housing is easily bent, and the slit is less likely to break. [Brief explanation of the drawing]
[0021] [Figure 1] Figure 1 is a schematic diagram of a guide wire system 10. [Figure 2] Figure 2 is a diagram showing a guide wire 30. [Figure 3] Figure 3 is a perspective view of a pressure sensor 11. [Figure 4] Figure 4 is a cross-sectional view showing the internal structure of a housing 34. [Figure 5] Figure 5 is a diagram showing slits 51 - 54. [Figure 6] Figure 6 is a partially enlarged view of Figure 5. [Figure 7] Figure 7 is an enlarged view showing a slit 51 according to a modified example. [Figure 8] Figure 8 is an enlarged view showing a slit 51 according to a modified example. [Figure 9] Figure 9 is a diagram showing a housing 34 according to a modified example. [Figure 10] Figure 10 is a diagram showing a housing 34 according to a modified example.
Mode for Carrying Out the Invention
[0022] [[ID=�9]]Hereinafter, preferred embodiments of the present invention will be described. It should be noted that each embodiment is merely one embodiment of the present invention, and it is needless to say that the embodiments can be changed without departing from the gist of the present invention.
[0023] [Guide Wire System 10] As shown in Figure 1, the guide wire system 10 includes a guide wire 30, an arithmetic unit 20, and a female connector 40 that connects the guide wire 30 and the arithmetic unit 20. The guide wire 30 is an elongated cord body and can be inserted into a blood vessel such as a coronary artery. The guide wire 30 has a pressure sensor 11 (see Figure 3, an example of a sensor) at its distal end that outputs electrical information according to pressure in the blood vessel.
[0024] The calculation unit 20 includes a power supply unit 21 that supplies current to the pressure sensor 11 of the guide wire 30, a calculation unit 22 that processes the electrical information output from the pressure sensor 11, and a memory 23 that stores the information necessary for the calculation process. The electrical information output from the pressure sensor 11 is transmitted from the guide wire 30 to the calculation unit 22 via the female connector 40 and cable 24. The calculation unit 22 calculates blood pressure based on the electrical information output from the pressure sensor 11. In other words, the guide wire system 10 is used to measure blood pressure.
[0025] In Figure 1, of the two ends of the guidewire 30, the fixed end (the end connected to the female connector 40) is the proximal end (the lower left end in Figure 1), and the free end (the tip when inserted into a blood vessel) is the distal end (the upper left end in Figure 1). In this specification, the side of the guidewire 30 with the proximal end is referred to as the proximal end side, and the side with the distal end is referred to as the distal end side.
[0026] [Guide wire 30] Figure 2 shows the guide wire 30. In Figure 2, the left side is the distal end of the guide wire 30, and the right side is the proximal end of the guide wire 30. The guide wire 30 is broadly divided into a tip portion 30A (an example of the distal end), a core wire 31 (an example of the main body), and a male connector 39 (an example of the connector). The tip portion 30A has a tip guide portion 32, a first helical body 33, a housing 34, and a second helical body 35. The axis 50 refers to the axis of the guide wire 30 when it is straight and not bent or curved.
[0027] The core wire 31 is a cylindrical member, for example, a solid stainless steel member. The tip guide portion 32 is a hemispherical member positioned at the distal end, convex towards the distal end, and by contacting the blood vessel wall, guides the guide wire 30 to follow the direction of travel along the blood vessel. The first helical body 33 and the second helical body 35 are wires 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 casing that houses the pressure sensor 11 in its internal space. The housing 34 is cylindrical in shape. The housing 34 has two through holes 41. The two through holes 41 are arranged 180° symmetrically with respect to the axis 50, and in Figure 2, only one of the through holes 41 is visible. Blood enters the interior of the housing 34 through the through holes 41 and comes into contact with the diaphragm 13 of the pressure sensor 11 (Figure 3). 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 Figure 3) extends from the distal end of the core wire 31 toward the housing 34 through the internal space of the second helical body 35. The tapered pin 38 is a member that reinforces the bending rigidity of the second helical body 35. The tapered pin 38 is cylindrical in shape, and its outer diameter gradually decreases from the distal end of the core wire 31 toward the housing 34. Although not shown in each figure, 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 helical body 33. The tip guide pin is cylindrical in shape and is a member that reinforces the bending rigidity of the first helical body 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 pressure sensor 11 and the computing device 20 are electrically connected when the male connector 39 is inserted into the female connector 40. The core wire 31, the first helical body 33, and the second helical body 35 are examples of wire materials.
[0030] As shown in Figure 3, the pressure sensor 11 comprises a sensor body 12, a diaphragm 13, a bridge circuit 14, four conductive wires 15, and a connector 16. The sensor body 12 is fixed to a tapered pin 38 fixed to a core wire 31 by a connector 16, which is made of adhesive, for example. 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 comprises four resistors 17, four terminals 18A and 18B, and four connectors 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 connector 19 electrically connects each resistor 17 to terminals 18A and 18B. Each conductive wire 15 is electrically connected to terminals 18A and 18B and extends through the internal space of the core wire 31 toward the base end, electrically connecting to each terminal of the male connector 39.
[0031] When the guidewire 30 is inserted into the blood vessel and blood pressure is applied to the pressure sensor 11, the diaphragm 13 elastically deforms in accordance with the blood pressure. As the diaphragm 13 elastically deforms, the four resistors 17 also elastically deform, and the electrical resistance values of the four resistors 17 change. 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 calculation device 20 (Figure 1) calculates the blood pressure.
[0032] As shown in Figure 4, the pressure sensor 11 is located in the internal space of the housing 34, proximal to the through-hole 41. In the housing 34, the internal space of the pressure sensor 11 proximal to the sensor body 12 is filled with synthetic resin 43. The internal space of the housing 34 distal to the through-hole 41 is also filled with synthetic resin 43. Slits 51 to 54, which will be described later, are located in the peripheral wall 42 of the housing 34 that partitions the internal space filled with synthetic resin 43. The synthetic resin 43 is, for example, epoxy resin, urethane resin, or polyamide elastomer resin.
[0033] [Slits 51, 52] As shown in Figure 5, the housing 34 has slits 51 to 54 formed therein. Each of the slits 51 to 54 penetrates the peripheral wall 42 of the housing 34. The slits 51 to 54 extend spirally around the axis 50 of the housing 34. As shown in Figure 6, when the housing 34 is viewed from a direction perpendicular to the axis 50, the narrow angle θ1 formed by the intersection of the extension direction Ds of the slits 51 to 54 and the axis 50 is constant, and in this embodiment it is approximately 60°. The extension directions Ds of the slits 51 to 54 are parallel. In this embodiment, when the housing 34 is viewed along the axis 50 from the proximal end to the distal end, the slits 51 to 54 each extend toward the distal end while rotating clockwise.
[0034] As shown in Figure 5, slits 51 and 52 are located proximal to the through-hole 41 in the housing 34. Slits 53 and 54 are located distal to the through-hole 41 in the housing 34. Slits 51 and 52 form a double spiral, alternately positioned with respect to the axis 50 of the housing 34. In other words, slits 51 and 52 are out of phase by half a period around the axis 50. To put it another way, slit 52 is located at a position that is half the distance that slit 51 travels along the axis 50 in the period of one rotation around the axis 50. Slits 53 and 54 also form a double spiral, similar to slits 51 and 52.
[0035] As shown in Figure 6, the slit 51 has a central portion 55 with a constant narrow 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 180° symmetrical with respect to the axis 50, so the end portion 56 located on the distal end side is shown by a dashed line in Figure 5. The two end portions 56 are symmetrical with respect to the axis 50 and in the direction of extension, but their positional relationship with respect to the central portion 55 is the same, so in the following, the end portion 56 located on the proximal end side will be used as an example for a detailed explanation.
[0036] As shown in Figure 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. Most of the end portion 56 is aligned with the bending direction De, which intersects the extension direction Ds. In this embodiment, the bending direction De is parallel to the axis 50. The connection point 57 between the central portion 55 and the end portion 56 has a smoothly curved R shape. Most of the end portion 56 extending towards 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 towards the proximal end.
[0037] Although a detailed explanation is omitted, slit 53 has a central portion and end portions similar to slit 51. In this embodiment, slits 52 and 54 do not have end portions 56 at both ends like slit 51, and extend along the extension direction Ds throughout their entire range.
[0038] [Effects of this embodiment] According to the guide wire 30 of the embodiment described above, since slits 51 to 54 are formed in the housing 34, the housing 34 is more easily bent and more easily stretched along the axis 50. Furthermore, since the formed slit 51 has a central portion 55 and an end portion 56, even if a tensile force along the axis 50 is applied to the housing 34, the end portion 56 is less likely to break.
[0039] Furthermore, since the synthetic resin 43 is filled into the internal space surrounded by the peripheral wall 42 where the slits 51 to 54 are located in the housing 34, the tensile force acting along the axis 50 of the housing 34 also acts on the synthetic resin 43, thereby improving the overall tensile strength of the housing 34 and the synthetic resin 43.
[0040] [Differentiation] In the embodiment described above, the bending direction De of the end portion 56 is along the axis 50, but the bending direction De does not have to be along the axis 50. For example, as shown in Figure 7, the narrow angle θ2 formed by the end portion 56 and the axis 50 may be 15°, 30°, 45°, etc. Also, as shown in Figure 8, the end portion 56 may curve in a U-shape from the central portion 55 and extend in the so-called opposite direction.
[0041] Furthermore, in the embodiments described above, the slits 51 and 53 have end portions 56, but as shown in Figure 9, the slits 51 and 53 may not have end portions 56 and may only have a central portion 55. In this embodiment, the tensile strength of the housing 34 is improved by the synthetic resin 43 filled in the internal space surrounded by the peripheral wall 42 in which the slits 51 to 54 are located in the housing 34.
[0042] Furthermore, in the embodiments described above, the slits 51, 52 and slits 53, 54 form a double spiral, but the slits 51 and 53 may be formed in the housing 34 as a single spiral without the provision of slits 52 and 54. Also, the pitch of the slits 51 does not have to be constant. For example, as shown in Figure 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 slit 51 (the distance along the axis 50 of adjacent slits 51) may be such that the pitch P1 at both ends is greater than the pitch P2 in the center (P1 > P2).
[0043] The smaller the spiral pitch of the slit 51, the easier it is for the housing 34 to stretch along the axis 50. Conversely, the larger the pitch, the greater the tensile strength along the axis 50. When a tensile force acts on the housing 34 along the axis 50, the central part 55 of the slit 51, where the pitch (P2) is small, stretches more than the ends where the pitch (P1) is large. As the central part 55 of the slit 51 stretches along the axis 50, the tensile length (stroke) until the housing 34 breaks becomes longer.
[0044] When the central portion 55 of the slit 51 stretches to its limit both in the center and at both ends, and eventually exceeds the tensile strength at both ends of the central portion 55, the housing 34 will break near the boundary between the central portion 55 and the end portions 56 (near both ends of the central portion 55). Therefore, by reducing the pitch P2 at the center of the central portion 55 of the slit 51, the slit 51 can stretch more easily along the axis 50, increasing the stroke required for the housing 34 to break. On the other hand, by increasing the pitch P1 at both ends of the central portion 55 of the 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 that measure physical quantities of blood and blood vessels other than pressure (temperature, flow velocity, etc.) may be provided. Also, the configuration of the distal end of the guidewire 30 shown in the above-described embodiment is merely one example, and it goes without saying that the configuration of the helical body, tapered pin, housing, etc. may be changed as appropriate. [Examples]
[0046] [Examples 1-5] A cylindrical pipe made of stainless steel (SUS304) with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm was used as the housing. The width of the slit was set to 0.02 mm, the narrow angle θ1 between the axis and the single spiral slit was set to 60°, and the narrow angle θ2 between the direction in which the end portion of the slit extends and the axis was set to 15°, 30°, and 45°. Examples 1-5 were formed, with the end portion parallel to the axis and the end portion curved in a U-shape (see Figure 8).
[0047] [Examples 6-8] Examples 6-8 were formed using a cylindrical stainless steel (SUS304) 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, the axis and the end portion of the single spiral slit extending parallel to the axis, and the radius of the boundary between the central portion and the end portion set to 0.05, 0.3, and 0.4.
[0048] [Comparative Example] A cylindrical pipe made of stainless steel (SUS304) with a length of 7 mm, an outer diameter of 0.37 mm, and a wall thickness of 0.03 mm was used as the housing, and a slit with a width of 0.02 mm was formed to create a single spiral slit along the axis without any end portions, which was used as a comparative example.
[0049] [Tensile strength] Using simulation software, a wire with a diameter of 0.08 mm was inserted into the housing to stabilize the shape of the slit spiral portion under tension. One end of the housing of each example and comparative example was fixed, and the tensile strength was determined when the other end was pulled. The material properties of SU S304 were set to a Young's modulus of 200 GPa, a Poisson's ratio of 0.3, a yield stress of 250 MPa, and a tangent coefficient of 1450 MPa. The results are shown in Table 1.
[0050] [Table 1]
[0051] As is clear from Table 1, all of Examples 1-8 showed improved tensile strength compared to the comparative example. In Examples 1-5, the tensile strength increased as the narrow angle θ1 increased. Also, Example 4, in which the direction in which the end portion of the slit extends was parallel to the axis, showed the strongest result. In Examples 6-8, the tensile strength increased as the R increased.
[0052] [Examples 9-12] Examples 9-12 were created using a cylindrical pipe made of stainless steel (SUS304) 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, where the ends of the single spiral slits extend parallel to the axis of the housing, and the pitch (distance between adjacent slits along the axial direction of the cylindrical pipe) of the single spiral slits, which have a total length of 7 mm, was set to 100 μm, 150 μm, 200 μm, and 280 μm, respectively.
[0053] Tensile strength tests were performed in Examples 9-12 using simulation software with the same settings as described above. Table 2 shows the stroke length (mm) and tensile strength (N) at the time of fracture. In Example 9, the maximum equivalent stress required for fracture was not reached 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 greater the tensile strength. From this, it can be said that a larger slit pitch makes the slit portion less stretchable, but increases the tensile strength. [Explanation of symbols]
[0056] 11. Pressure sensor (sensor) 30... Guidewire 31. Core wire (wire material) 33...1st helix (wire rod) 34. Housing 35...Second helix (wire rod) 42...peripheral wall 43. Synthetic resin 51-54... Slit 55...Central part 56...end part
Claims
1. Wire material and, A cylindrical housing attached to the above wire, The housing is equipped with a sensor located in the internal space of the housing, The above housing has a first slit that extends spirally through the peripheral wall of the housing, In the housing described above, the portion of the internal space surrounded by the peripheral wall where the first slit is located that is closer to the sensor is filled with synthetic resin. The above housing further has through holes, The above sensor has a diaphragm that extends in a direction intersecting the peripheral wall of the housing, In the internal space of the housing described above, a guide wire has a space on the side of the through-hole from the diaphragm that is not filled with the synthetic resin, so that the liquid that enters through the through-hole can come into contact with the diaphragm.
2. The first slit described above is A central portion that extends spirally in a certain direction along the peripheral wall, The guide wire according to claim 1, having an end portion that includes one end of the first slit, intersects the extension direction, and is bent relative to the central portion along a bending direction in which the spiral pitch increases.
3. The guide wire according to claim 2, wherein the bending direction is parallel to the axis of the housing.
4. The guide wire according to claim 2, wherein the end portion is curved in a U-shape.
5. The guide wire according to any one of claims 2 to 4, wherein the bend between the central portion and the end portion is R-shaped.
6. The guide wire according to any one of claims 2 to 5, wherein the spiral pitch in the central portion of the first slit is greater at both ends than at the center.
7. The above housing further has a second slit that extends spirally through the peripheral wall of the housing, The guide wire according to any one of claims 1 to 6, wherein the first slit and the second slit form a double spiral that is alternately positioned with respect to the axial direction of the housing.