Guide wire and catheter

Abstract

Provided are a catheter and a guide wire with which information for assisting insertion can be easily obtained. The guide wire includes a strain gauge (14). The guide wire has, in the vicinity of a distal end, a boundary (B) where the rigidity changes. A first Young's modulus in a first portion (131) on the proximal side of the boundary (B) is greater than a second Young's modulus in a second portion (132) on the distal side of the boundary (B). The strain gauge (14) measures, in the second portion (132) which is at least on the distal side of the boundary (B), strain related to compression and extension along the extension direction of the second portion (132).

Description

Guidewires and catheters

[0001] The present disclosure relates to guidewires and catheters.

[0002] There is a technology to improve the operability of inserting a guidewire used to introduce a catheter into a patient's body, etc. In Patent Document 1, by connecting sections made of different materials along the length of the guidewire from the tip, both operability and bending resistance are achieved.

[0003] JP 2008-110266 A

[0004] A guidewire is inserted into a tortuous blood vessel or the like inside the body, and therefore must be inserted safely along a precise path. An object of the present disclosure is to provide a guidewire and a catheter that can easily obtain information to assist insertion.

[0005] In order to achieve the above object, one aspect of the guide wire of the present disclosure comprises a strain gauge, and has a boundary near the tip where stiffness changes, a first Young's modulus on the base side of the boundary is greater than a second Young's modulus on the tip side of the boundary, and the strain gauge measures strain related to compression and extension along the extension direction of the tip side at least on the tip side of the boundary.

[0006] Another aspect of the guide wire of the present disclosure comprises a strain gauge, and has a boundary near the tip where stiffness changes, a first Young's modulus on the base side of the boundary is greater than a second Young's modulus on the tip side of the boundary, and the strain gauge measures strain associated with bending in a direction perpendicular to the extension direction of the tip side at least on the tip side of the boundary.

[0007] Another aspect of the guide wire of the present disclosure includes a strain gauge, and has a boundary near the tip where stiffness changes, a first transverse elastic modulus on the base side of the boundary is greater than a second transverse elastic modulus on the tip side of the boundary, and the strain gauge measures strain related to torsion on the tip side at least on the tip side of the boundary.

[0008] According to the present disclosure, it is possible to easily obtain support information regarding the insertion of a guidewire.

[0009] FIG. 1 is an overall configuration diagram of a catheter system. FIG. 2 is a diagram showing a cross-sectional structure near the tip of a guide wire. FIG. 3 is a diagram explaining strain measurement. FIG. 4 is a diagram explaining strain measurement. FIG. 5 is a plan view explaining strain gauges. FIG. 6 is a diagram explaining detection of strain related to expansion and contraction deformation. FIG. 7 is a diagram explaining detection of strain related to bending deformation. FIG. 8 is a diagram explaining detection of strain related to torsional deformation. FIG. 9 is a cross-sectional view of another example showing the positional relationship of strain gauges. FIG. 10 is a diagram showing a configuration related to processing of detection results of strain gauges. FIG. 11 is a diagram showing a configuration related to processing of detection results of strain gauges. FIG. 12 is a diagram showing a configuration related to processing of detection results of strain gauges. FIG. 13 is a flowchart showing a control procedure for load detection processing.

[0010] An embodiment will be described below with reference to the drawings. Fig. 1 is a diagram showing the overall configuration of a catheter system 100 including a guidewire 1 according to this embodiment. The catheter system 100 includes the guidewire 1, catheters 3 and 4, Y-shaped connectors 5 and 6, extension tubes 7 and 8, a torquer 9, and the like.

[0011] The guidewire 1 is inserted into the human body to the target location, in this case a blood vessel, ahead of the catheter 3. The guidewire 1 is inserted into the catheter 3 and the catheter 4 which is inserted into the catheter 3. After the catheters 3 and 4 reach the target location, the guidewire 1 can be removed from the catheters 3 and 4. The structure of the guidewire 1 will be described later.

[0012] The catheter 3 may be a guiding catheter. Here, the catheter 3 guides the catheter 4 passing through the tube of the catheter 3 to near the target location. In this case, the guidewire 1 may be one of the components of the catheter 3. Alternatively, if a guiding catheter is not required, the catheter 3 itself may be a catheter for performing a desired treatment at the target location.

[0013] The catheter 4 is a catheter for performing a desired treatment at a target location and is selected depending on the application. The catheter 4 may be, for example, a balloon catheter. The guide wire 1 may be one of the components of the catheter 4.

[0014] The Y-shaped connector 5 is connected to the base end of the catheter 3 and is bifurcated at the proximal end. The catheter 4 is inserted into one of the bifurcations of the Y-shaped connector 5. One end of an extension tube 7 is connected to the other bifurcations of the Y-shaped connector 5. A triple stopcock C, for example, may be connected to the other end of the extension tube 7 opposite to the one end thereof. The triple stopcock C may be connected to, for example, a tube for supplying physiological saline or a tube for monitoring arterial blood pressure.

[0015] The Y-shaped connector 6 is connected to the proximal end of the catheter 4 and is bifurcated at the proximal end. The guidewire 1 extends from one of the two prongs of the Y-shaped connector 6. That is, the guidewire 1 is connected to the torquer 9 at the proximal end. A signal line (described later) related to detecting the state of the guidewire 1 may be connected to the connection terminal of the torquer 9 or may be drawn out from other Y-shaped connectors 5, 6, etc. and connected to an information processing device I. The information processing device I may be, for example, a PC (Personal Computer). Alternatively, the information processing device I may be a device including a microcomputer specifically designed or programmed for signal processing to detect the state of the tip of the guidewire 1. An extension tube 8 is connected to the other prong of the Y-shaped connector 6 opposite the one prong. The extension tube 7 may be connected to an operating mechanism H of the catheter 4. The operating mechanism H may be, for example, an indeflator for inflating and deflating the balloon when the catheter 4 is a balloon catheter.

[0016] The torquer 9 is an operating mechanism for the guidewire 1. For example, the torquer 9 has a through-hole through which the guidewire 1 passes and is fixedly held. When an operator operates an operating part of the torquer 9, the guidewire 1 is pushed / pulled or rotated in conjunction with the operation.

[0017] The information processing device I identifies the state of the tip of the guidewire 1 based on a signal input from the guidewire 1. If the identified state is undesirable or abnormal, the information processing device I performs a predetermined notification operation via a display, a notification mechanism, or the like (not shown). The notification mechanism may include, for example, a mechanism for emitting an alarm sound such as a beep or a speaker for outputting a warning voice. The content of the predetermined notification operation may vary depending on the type of abnormality, etc. The notification mechanism may be part of the configuration of the information processing device I, or may be a separate configuration from the information processing device I.

[0018] Next, the guidewire 1 will be described. Figure 2 is a diagram showing the cross-sectional structure of the vicinity of the tip of the guidewire 1. As described above, the vicinity of the tip of the guidewire 1 protrudes and is exposed from the tip of the catheter 3, and is inserted into a blood vessel or the like prior to the catheter 3. The guidewire 1 includes a round cap 11 at its tip, a spring 12, and a core wire 13. The core wire 13 extends along a central axis W0 in the extension direction of the guidewire 1. The spring 12 is positioned surrounding a tip portion 13a and a tapered portion 13b of the core wire 13, which extends to the round cap 11. The base portion 13c and the tip portion 13a of the core wire 13 are connected by the tapered portion 13b.

[0019] The spring 12 has a smaller orbital diameter toward the tip in the middle of the tip portion 13a of the core wire 13. At the tip, the orbital diameter of the spring 12 is approximately the same as the diameter of the round cap 11.

[0020] The core wire 13 and the spring 12 are metal members, and may be made of, for example, an aluminum alloy, platinum, tin, gold, silver, stainless steel (SUS), brass, copper, or a magnesium alloy. The core wire 13 and the spring 12 may also be coated with an appropriate material. The core wire 13 and the spring 12 may be made of the same material or different materials. The wire diameter of the core wire 13 may be approximately the same as or slightly smaller than the wire diameter of the spring 12.

[0021] The distal end portion 13a of the core wire 13 further includes a first portion 131 on the base side and a second portion 132 on the distal side, the first portion 131 being connected to the second portion 132 across a boundary B. That is, the first portion 131 and the second portion 132 are discontinuous across the boundary B. The boundary B may be perpendicular to the axial direction of the core wire 13, i.e., the extension direction. The rigidity of the first portion 131, i.e., the longitudinal modulus (first Young's modulus) and transverse modulus of elasticity, is higher than the rigidity of the second portion 132, i.e., the second Young's modulus and transverse modulus of elasticity. That is, the second portion 132 is more easily compressed / extended and bent / twisted than the first portion 131. Here, the first portion 131 has a larger diameter than the second portion 132. Additionally or alternatively, the first portion 131 and the second portion 132 may be made of different materials. The rigidity of the first portion 131 may be significantly greater than the rigidity of the second portion 132. Here, "sufficiently" refers to a difference of at least 1.5 times, for example, a difference of one digit (factor 10) or more. When the materials are the same, the first portion 131 and the second portion 132 may be obtained integrally across the boundary B. When the materials are different, the first portion 131 and the second portion 132 may be appropriately joined together.

[0022] 3A and 3B are diagrams illustrating strain measurement. FIGS. 3A and 3B are views of the side of the core wire 13 viewed from opposite sides, here, from the ±v direction in the uv plane. The guide wire 1 includes a strain gauge 14. Multiple strain gauges 14a-14g and a strain gauge 14h are fixed to the side of the core wire 13. For example, the strain gauges 14a-14h are located at least near the base of the second portion 132 of the core wire 13. As shown in these figures, the strain gauges 14 may not be located in the first portion 131 and may not measure the strain of the first portion 131. Signal lines (not shown) are connected to the strain gauges 14a-14h, respectively. The signal lines may be located along the guide wire 1 or built into the guide wire 1, and may be separated from the guide wire 1 and drawn out at the torquer 9 or the Y-connectors 5 and 6, as described above.

[0023] 4 is a plan view illustrating the strain gauge 14. The strain gauge 14 includes a base 140, a resistor 141, two terminals 142, and a connection wire 143 that connects the terminals 142 and the resistor 141. The base 140 is a film-like insulating member. The base 140 may be attached to the core wire 13. The base 140 insulates the resistor 141, the terminals 142, and the connection wire 143 from the core wire 13. The insulating member may be, for example, polyimide or polyester.

[0024] The resistor 141 is a rectangular conductor formed by zigzag bending of a thin wire. The extending direction of the thin wire is the gauge direction, i.e., the direction of strain detection, which is referred to here as the x-direction. The resistor 141 expands and contracts in the gauge direction due to strain, and a change in resistance value is detected. The conductor may be, for example, a copper-nickel alloy, chromium, or chromium nitride. In a standard state with no strain, the resistance values ​​of the resistors 141 of the strain gauges 14a to 14h may be equal.

[0025] The connection wiring 143 is connected to each end of the resistor 141, and extracts a signal from the resistor 141. The connection wiring 143 may be made of the same material as the resistor 141, or may be integral with the resistor 141.

[0026] The two terminals 142 are located near the other end of the connection wiring 143 opposite the end connected to the resistor 141, and are connected to the connection wiring 143. The terminals 142 may overlap the other end of the connection wiring 143. The terminals 142 are connected to an external signal line (not shown) that extracts a signal generated in the resistor 141 of the strain gauge 14. The terminals 142 may be made of the same material as the connection wiring 143. Alternatively, the terminals 142 may be made of a different type of conductive metal than the connection wiring 143 and stacked on top of the connection wiring 143.

[0027] As described above, the strain gauge 14 is positioned near the rigidity boundary B in the distal end portion 13a, thereby detecting a load corresponding to the stress between the first portion 131 and the second portion 132. In FIGS. 3A and 3B , the gauge directions of the strain gauges 14a to 14d and 14h are aligned along the axial direction w of the guide wire 1. The strain gauges 14c and 14d are positioned 90 degrees apart from the strain gauge 14b in the rotational direction about the central axis W0 of the guide wire 1, which is aligned along the axial direction w, and are 180 degrees opposite each other, i.e., symmetrical with respect to the central axis W0. The strain gauge 14h is further positioned 180 degrees opposite the strain gauge 14b in the rotational direction about the central axis W0 of the core wire 13. The gauge direction of the strain gauge 14e is perpendicular to the axial direction w of the guide wire 1. The gauge directions of the strain gauges 14f and 14g are tilted 45 degrees with respect to the central axis W0 of the core wire 13 and are 90 degrees apart from each other.

[0028] The strain gauges 14a to 14d, 14h can detect expansion and contraction in response to a load along the extension direction of the guide wire 1, i.e., in the axial direction w of the guide wire 1. The pair of strain gauges 14b, 14h detects bending (bending) in response to a load in a second direction v perpendicular to the axial direction w of the guide wire 1. The pair of strain gauges 14c, 14d detects bending (bending) in response to a load in a first direction u perpendicular to the axial direction w and the second direction v of the guide wire 1. The expansion and contraction in the axial direction w is determined by Young's modulus E.

[0029] 5A to 5C are diagrams illustrating strain detection. FIG. 5A is a diagram illustrating expansion / contraction deformation. The expansion / contraction amount ΔL of the distal end portion 13a, i.e., the sum of the displacement amount ΔL1 of the first portion 131 and the displacement amount ΔL2 of the second portion 132, depends on the composite spring constant K of the first portion 131 and the second portion 132, and is expressed as P = K ΔL = K (ΔL1 + ΔL2) with respect to the external load P. The spring constant k1 of the first portion 131 and the spring constant k2 of the second portion 132 are expressed as ki = Ei Ai / Li based on the Young's moduli E1 and E2, cross-sectional areas A1 and A2, and lengths L1 and L2, respectively. Because the force applied to both ends of the second portion 132 is equal, the composite spring constant K = E1 E2 A1 A2 / (E1 A1 L2 + E2 A2 L1). Therefore, the composite spring constant K is expressed by the following equation 1: K=E2·A2 / (L2+(E2·A2) / (E1·A1)·L1) (Equation 1)

[0030] If there is no significant difference between the cross-sectional areas A1 and A2, and no significant difference between the lengths L1 and L2, and if Young's modulus E1 is sufficiently greater than Young's modulus E2, the second term in the denominator will be sufficiently smaller than the first term. Therefore, the combined spring constant K is significantly affected by the deformation of the second portion 132, and is approximately expressed by the following equation 2: K≈E2·A2 / L2 (Equation 2)

[0031] Therefore, the correspondence relationship between the external load P, which is the load on the guidewire 1, and the amount of deformation is expressed by Equation 3: P≈E2·A2 / L2·(ΔL1+ΔL2) (Equation 3) When the strains ΔL1 / L1 and ΔL2 / L2 are measured, the amounts of displacement ΔL1 and ΔL2 are determined, and the external load P is obtained accordingly. Furthermore, when Young's modulus E1 is sufficiently greater than Young's modulus E2, the amount of displacement ΔL1 is sufficiently smaller than the amount of displacement ΔL2, and the relationship of Equation 4 is obtained approximately: P≈E2·A2·(ΔL2 / L2) (Equation 4) Therefore, this guidewire 1 can selectively detect the external load P in the direction of compression and extension of the distal end portion 13a, particularly the second portion 132. Because the guidewire 1 is inserted into a branched and bent interior of a blood vessel or the like, it is also affected by loads corresponding to the bends along the way. In this way, by selectively detecting the load on the tip of the guide wire 1, it is possible to determine with high accuracy whether the tip of the guide wire is pressing against the inner wall of the blood vessel more than necessary when the guide wire is inserted.

[0032] Although the measurement of the strain ΔL1 / L1 itself has been omitted here as an approximation, the strain may be detected in the first portion 131 as well as the second portion 132. This allows the external load P to be obtained more accurately without using an approximation formula. Even in this case, the strain ΔL1 / L1 in the first portion 131 is smaller than the strain ΔL2 / L2 in the second portion 132, and the load on the distal end of the guidewire 1 is mainly obtained. Furthermore, because the strain ΔL1 / L1 in the first portion 131 and the strain ΔL2 / L2 in the second portion 132 are obtained separately, if the strain ΔL2 / L2 in the second portion 132 is temporarily large, it can be determined that this is not an increase in the load on the distal end.

[0033] In the case of this contraction / extension, in addition to strain gauge 14a, strain gauges 14b to 14d and 14h positioned at 90-degree intervals around the central axis W0 show approximately the same changes. Therefore, one strain gauge 14a is sufficient to actually measure contraction / extension. Alternatively, measurement accuracy may be improved by averaging the measurement results of multiple strain gauges 14.

[0034] The strain gauges 14c and 14d, located symmetrically with respect to the central axis W0 of the core wire 13, detect bending of the guide wire 1 in the first direction u. When bending in the first direction u occurs, the resistor 141 of the strain gauge 14 located toward the center of the curvature circle associated with the bending, i.e., on the bending side, contracts, while the resistor 141 of the strain gauge 14 located outside the curvature circle, i.e., on the opposite side from the bending side, expands. This identifies that the guide wire 1 has bent toward the strain gauge 14 associated with the resistor 141 that detected the contraction. Note that the direction perpendicular to the axial direction w of the guide wire 1 is represented by two axes. Therefore, in addition to the above, bending in a second direction v perpendicular to the axial direction w and the first direction u can also be detected by the strain gauge 14b and the strain gauge 14h located symmetrically with respect to the central axis W0, i.e., 180 degrees opposite in the rotational direction around the central axis W0. Therefore, bending of the guide wire 1 in any direction can be detected by the strain gauges 14b to 14d and 14h. Furthermore, by combining multiple strain gauges 14 in this manner, it is possible to distinguish between contraction / extension and bending. Note that, as long as the strain gauges 14c, 14d and the strain gauges 14b, 14h are smaller than the circumferential length of the core wire 13, they may be positioned circumferentially without being shifted in position in the axial direction w.

[0035] 5B is a diagram illustrating bending deformation. When an external load P is applied in the bending direction to the second portion 132, which has a length L2 and a diameter d2 (radius r2), and the rigidity of the first portion 131, i.e., Young's modulus E1, is sufficiently greater than the Young's modulus E2 of the second portion 132, deflection approximately occurs only in the second portion 132. At a position displaced by Δh in the radius of curvature direction from the central axis W0, the length of the arc of angle dθ changes from R·dθ to (R+Δh)·dθ, so the strain ε2 is expressed by the following equation 5: ε2=((R+Δh)·dθ-R·dθ) / (R·dθ)=Δh / R (Equation 5)

[0036] Since the strain gauge 14 is located on the surface of the core wire 13, Δh is the radius r2 of the core wire 13 = d2 / 2. Meanwhile, the bending stress σ is expressed as E2·ε2 using Young's modulus E2, and the radius of curvature R is expressed as E2·I2 / M2 using the bending moment M2 around the central axis and the second moment of area I2. Furthermore, the bending moment M2 = P2·L2 depending on the load P2. Therefore, the following equation 6 is obtained: ε2 = r2·P2·L2 / (E2·I2) ... (Equation 6)

[0037] By transforming this formula 6 for the load P2, formula 7 is obtained. P2 = (E2 * I2 / (r2 * L2)) * ε2 (formula 7) Note that the length L2 here is the distance from the boundary B between the first portion 131 and the second portion 132 to the strain gauges 14c and 14d. Furthermore, the second moment of area I2 for a cylinder with a diameter d2 is I2 = π * (d2) ４ / 64 = π · (r2) ４ / 4. Therefore, the bending deformation of the guidewire 1 in a plane perpendicular to the initial axial direction w can be selectively and accurately determined based on the measurement results of the strain ε2 by the strain gauges 14c and 14d. By selectively detecting bending deformation near the tip of the guidewire 1 in this manner, it is possible to determine whether an excessive load in the bending direction is being applied to the tip of the guidewire 1. Note that in the above example, the first portion 131 is assumed to be unbendable, and the strain associated with the bending of the first portion 131 is not detected. However, the strain in the bending direction of the first portion 131 may also be detected. By detecting both the strain in the bending direction of the first portion 131 and the strain in the bending direction of the second portion 132, the load on the tip can be determined more accurately. Furthermore, if the load on the first portion 131 in the bending direction is large, it can be easily determined that this is different from the load on the tip.

[0038] The gauge directions of strain gauges 14f and 14g are inclined at 45 degrees with respect to the axial direction w. The inclination direction of strain gauge 14f and the inclination direction of strain gauge 14g are perpendicular to each other. These strain gauges 14f and 14g detect rotational strain due to twisting around the axis of the guide wire 1. By combining these detection results, a value that is closest to the load on the tip of the guide wire 1 is detected.

[0039] FIG. 5C is a diagram illustrating torsional deformation. Here, strain gauge 14f is described, but results can also be obtained for strain gauge 14g by changing only the parameters of the same equation. The shear strain γ2 associated with torsion is expressed by Equation 8 using the length L2, radius r2, and torsion angle φ2 of the second portion 132: γ2 = r2 · φ2 / L2 (Equation 8). Here, length L2 is the distance from the boundary B between the first portion 131 and the second portion 132 in the axial direction w to the strain gauge 14f. The shear stress τ2 is expressed as τ2 = G2 · γ2 due to the transverse elastic modulus G2 of the second portion 132. Meanwhile, the torque T2 of the second portion 132 is expressed as T2 = Zp · τ2 due to the torsional section modulus Zp. The torsional section modulus Zp is expressed as Zp = Ip / r2 due to the polar moment of inertia Ip. Therefore, torque T2 can be calculated using Equation 9. T2 = (G2 · Ip / r2) · γ2 (Equation 9) For a circular cross section with a diameter d2 and a radius r2, Ip2 = π · (d2) ４ / 32 = π · (r2) ４ / 2.

[0040] In this case, too, the transverse elastic modulus G1 of the first portion 131 is sufficiently larger than the transverse elastic modulus G2, so that the torsion of the first portion 131 is negligible compared to the torsion of the second portion 132. That is, this guidewire 1 is capable of selectively and accurately detecting the torque T2 associated with torsion based on the measurement results of the shear strain γ2 of the second portion 132 near the distal end of the guidewire 1. Alternatively, the strain of the first portion 131 may also be detected without being ignored, and the torque may be evaluated based on the combined value of the transverse elastic moduli G1 and G2.

[0041] In the present disclosure, the strain gauge 14e is not directly used to detect the above three types of strain, but may be used for temperature compensation. Note that, to reduce the influence of strain, only the strain gauge 14e may be located in the first portion 131. The strain gauge 14e will be described later.

[0042] FIG. 6 is a cross-sectional view of another example showing the positional relationship of the strain gauge 14. This cross-section is indicated by the cross-sectional line AA in FIGS. 3A and 3B . The outer peripheral surface of the second portion 132 and the inner surface of the spring 12 may be in substantial contact with each other. In this case, the strain gauge 14 may be bonded to the inner surface of the spring 12 instead of to the outer peripheral surface of the second portion 132. The strain gauge 14 can detect each component of strain. In this case, the compression / extension component of the second portion 132 may appear as a lateral compression / extension component of the spring 12. The torsion component of the second portion 132 may appear as a compression / extension component of the spring 12. The bending component of the second portion 132 may appear as a torsion component of the spring 12. Furthermore, depending on the measurement purpose, a portion of the strain gauge 14 may be bonded to the outer peripheral surface of the second portion 132, and the remaining portion may be bonded to the inner surface of the spring 12.

[0043] 7A to 7D are diagrams showing a configuration for processing the detection results of the strain gauges 14. The change in electrical resistance between both ends of the terminals 142 of each strain gauge 14 is very small under normal strain. Therefore, the electrical signal may be acquired by subtracting a reference value or amplifying it as appropriate. A Wheatstone bridge circuit, for example, may be used to subtract the reference value. A Wheatstone bridge circuit is a circuit that detects the difference between the divided voltage of two of the four resistors and the divided voltage of the other two resistors. By amplifying the difference value, the amplifier gain can be appropriately obtained without increasing the output width.

[0044] As shown in FIG. 7A, the resistor 141 of any one of the strain gauges 14 can be used as one resistor in a Wheatstone bridge circuit. The resistance values ​​of the other three resistor elements R2 to R4 are fixed at R0, the resistance value when resistor 141 is not strained. This allows for a voltage to be obtained that corresponds to the ratio of the original resistance value R0 of resistor 141 to the change in resistance value ΔR. That is, if the resistance value of resistor 141 is R0 relative to the input Vin, the potential at both points n1 and n2 becomes Vin / 2, and the output voltage Vout = 0. When the resistance value of resistor 141 changes, the potential at point n1 changes from Vin / 2 accordingly, causing the output voltage Vout to deviate from 0. This allows the resistance value of resistor 141 to be calculated, and the magnitude of strain corresponding to that resistance value to be determined. To reduce the effects of parasitic resistance in the circuit, resistor elements R2 to R4 may be located near the tip portion 13a.

[0045] Alternatively, as shown in FIG. 7B , the Wheatstone bridge circuit may include multiple resistors 141 of strain gauges 14, for example, two resistors 141 arranged in series at appropriate positions. The other two fixed resistors arranged in series are arranged in parallel. In this case, when the resistors 141 are arranged in series, even if the resistance of one resistor 141 changes due to temperature changes or other factors regardless of strain, no change occurs in the voltage division. In other words, the effects of temperature-induced changes in resistance are canceled out by the two resistors 141. When the gauge direction of one of the two resistors 141 is perpendicular to the axial direction w, i.e., when it is the resistor 141 of the strain gauge 14e, the effects of temperature are canceled out by the strain of the other resistor 141, and the amount of expansion / contraction deformation is determined, as described above.

[0046] 7C , strain gauges 14c and 14d may have two resistors 141 arranged in series and positioned on opposite sides of the central axis W0 of the core wire 13. In this case, the strains due to compression and extension are equal and canceled out by the two resistors 141. Therefore, the strain due to bending in the second direction v can be obtained. Alternatively, if the resistors 141 of the strain gauges 14c and 14d are positioned diagonally in the Wheatstone bridge circuit, the strains due to bending are canceled out, and the strain due to compression and extension can be obtained more accurately.

[0047] 7B and 7C, four resistors 141 can be connected to a Wheatstone bridge circuit, thereby eliminating the influence of temperature and compressive and tensile stresses and obtaining bending stress measurement results.

[0048] As shown in FIG. 7D , the obtained voltage signal is amplified by an amplifier and then converted into digital data by an ADC 211 (Analog / Digital Converter) in an AFE 21 (Analog Front End). The digital data only needs to have a time resolution that does not cause delays that affect the operator's operation and a voltage resolution that allows appropriate determination of overload, etc. The digital data is temporarily stored in a memory 222 of the control unit 22 and analyzed by a CPU 221 (Central Processing Unit). The CPU 221 may be a general-purpose processor or may be implemented by a hardware circuit such as a microcomputer specialized for the analysis process. The memory 222 stores parameter settings 2221 for the guidewire 1. Appropriate parameters can be acquired by registering and setting information about the guidewire 1 to be used in advance.

[0049] 8 is a flowchart showing the control procedure of the load detection process executed by the CPU 221. This process can be repeatedly executed until it is terminated by an external command or the like.

[0050] The CPU 221 acquires information such as the elastic modulus of the target guide wire 1, parameters relating to the shape of the core wire 13, and the position of the strain gauge 14 from the parameter setting 2221 (S1).

[0051] The CPU 221 acquires digital data representing the magnitude of strain measured by each strain gauge from the ADC 211 (S2). Based on the acquired data, the CPU 221 calculates the compression / extension load, bending load, and torque around the central axis (S3).

[0052] The CPU 221 compares the calculated load and torque with reference values ​​to determine whether an abnormal load has occurred (S4). The CPU 221 determines whether an abnormality has been determined (S5). If it is determined that no abnormality has been determined (S5; NO), the processing of the CPU 221 returns to step S2.

[0053] If it is determined that an abnormality has been detected (S5; YES), the CPU 221 outputs notification control information indicating the type of abnormality and the notification content according to the abnormality level to the notification unit that performs the notification operation (S6).Then, the processing of the CPU 221 returns to step S2.

[0054] As described above, the guidewire 1 of this embodiment includes a strain gauge 14. The guidewire 1 has a boundary B near the tip where the rigidity changes. The first Young's modulus in the first portion 131, which is closer to the base than the boundary B, is greater than the second Young's modulus in the second portion 132, which is closer to the tip than the boundary B. The strain gauge 14 measures strain related to compression and extension along the extension direction of the tip side, at least on the tip side of the boundary B. In this way, since the guidewire 1 has a boundary B near the tip and the rigidity on the base side is relatively high, it is easy to selectively measure strain on the tip side. This allows the guidewire 1 to detect the load on the tip corresponding to the movement of the tip, such as during insertion, with greater accuracy than conventional methods.

[0055] In particular, based on the length L2 along the guidewire 1 of the second portion 132 distal to the boundary B, the cross-sectional area A2 perpendicular to the extension direction of the guidewire 1, the magnitude of compression / extension ΔL2, and the Young's modulus E2, the load P associated with compression / extension on the guidewire 1 may be expressed as P=E2·A2·(ΔL2 / L2) using the strain (ΔL2 / L2). In this way, the influence of the deformation of the first portion L1 on the load P can be approximately ignored, and the guidewire 1 can selectively and accurately detect the load on its distal end.

[0056] Furthermore, the strain gauge 14 does not need to measure the strain in the first portion 131 that is closer to the base than the boundary B. If the difference in rigidity between the first portion 131 and the second portion 132 is sufficiently large, the strain in the first portion 131 will be negligibly small compared to the strain in the second portion 132. Therefore, the guide wire 1 can accurately obtain the load on the tip from only the strain in the second portion 132, without measuring the strain in the first portion 131.

[0057] Furthermore, a core wire 13 positioned along a central axis W0 in the extension direction of the guide wire 1 and a spring 12 surrounding the core wire 13 may be located near the tip of the guide wire 1. The strain gauge 14 may be attached to the side of the core wire 13. Since the strain of a member along the axis of the guide wire 1 is directly measured, the guide wire 1 can easily detect a load with high accuracy.

[0058] Furthermore, the guide wire 1 may be thinner on the distal side of the boundary B than on the proximal side of the boundary B. The difference in rigidity is determined by the shape, material, thickness, etc., but by varying the thickness structurally to vary the rigidity, a suitable guide wire 1 can be easily obtained.

[0059] Furthermore, the catheter 3 or catheter 4 of the present embodiment may be provided with the above-described guide wire 1. By providing the guide wire 1 of the present disclosure, the catheters 3 and 4 can be inserted more safely and reliably into the target position.

[0060] Alternatively, the guidewire 1 includes a strain gauge 14. The guidewire 1 has a boundary B near the tip where the rigidity changes. The first Young's modulus in the first portion 131 on the base side of the boundary B is greater than the second Young's modulus in the second portion 132 on the tip side of the boundary B. The strain gauge 14 measures strain associated with bending in a direction perpendicular to the original axial direction w on the tip side in at least the second portion 132 on the tip side of the boundary B. In this way, since the guidewire 1 has the boundary B near the tip and the rigidity on the base side is relatively high, it is easy to selectively measure strain on the tip side. This allows the guidewire 1 to detect the load on the tip corresponding to the movement of the tip, such as during insertion, with greater accuracy than conventional methods.

[0061] In particular, the load P may be expressed as P=(E2·I2 / (r2·L2))·ε2 based on the distance L2 from the boundary B to the strain gauges 14c, 14d in the second portion 132 on the distal side, the moment of inertia I2 of the guide wire 1 in the second portion 132, the radius r2 of the cross section, the strain ε2 associated with bending, and the Young's modulus E2. In this way, even if the first portion L1 is approximately ignored, the load on the distal end of the guide wire 1 can be selectively detected with high accuracy.

[0062] Alternatively, the strain gauges 14 may be multiple strain gauges 14a to 14c, 14h positioned symmetrically with respect to the central axis in the extension direction of the guide wire 1, and the difference between the measurement results at positions symmetrical with respect to this central axis may be output. The difference between the strain gauges 14 positioned in such symmetrical directions can more accurately determine the strain ε2 related to bending while canceling out the strain related to compression and extension that does not depend on the position with respect to the central axis.

[0063] Furthermore, four strain gauges 14 may be positioned symmetrically about the central axis along a first direction u and a second direction v, which are two orthogonal axes in a plane perpendicular to the central axis. Since the bending direction of the guidewire 1 is indefinite, by making it possible to detect along the two orthogonal axial directions, the bending state of the tip of the guidewire 1 can be identified with high precision and reliability.

[0064] Alternatively, the guidewire 1 includes a strain gauge 14. The guidewire 1 has a boundary B near the distal end where the rigidity changes. The first transverse elastic modulus in a first portion 131 located closer to the base than the boundary B is greater than the second transverse elastic modulus in a second portion 132 located closer to the distal end than the boundary B. The strain gauge 14 measures strain associated with torsion on the distal end side in at least the second portion 132 located closer to the distal end than the boundary B. In this way, since the guidewire 1 has the boundary B near the distal end and the rigidity on the proximal side is relatively high, it is easy to selectively measure strain on the distal end side. This allows the guidewire 1 to detect the load associated with torsion on the distal end in response to the movement of the distal end, such as during insertion, more accurately than conventional methods, according to Equation (9).

[0065] In particular, based on the polar moment of inertia Ip, the radius of cross section r2, the shear strain γ2, and the modulus of transverse elasticity G2 of the distal end second portion 132, the torque T2 associated with the torsion of the second portion 132 may be expressed as T2 = (G2 · Ip / r2) · γ2. With the above shape, the torque T2 can be easily and accurately obtained approximately using only the parameters of the second portion 132.

[0066] The guide wire 1 may also include two strain gauges 14 for measuring torsion. The gauge directions of the two strain gauges 14f, 14g may be inclined at 45 degrees with respect to the central axis W0 of the second portion 132 when viewed from the outside along the radial direction of the central axis W0, and may be oriented 90 degrees apart from each other. Arranging the strain gauges 14f, 14g in this positional relationship allows for selective and accurate measurement of strain caused by torsion.

[0067] The present disclosure is not limited to the above-described embodiment and may be modified in various ways. For example, in the above embodiment, the plurality of strain gauges 14 are positioned so as to be able to detect all of the loads of compression, extension, bending, and torsion, but this is not limiting. It is also possible that only one or two types of loads may be detected.

[0068] The shape of the strain gauge 14 is not limited to the above, as long as it has a shape that allows detection of strain in a specific direction.

[0069] Furthermore, since it is sufficient to obtain two components for each of compression / extension, bending, and twisting, the gauge directions of the two strain gauges 14 for obtaining the two components do not necessarily need to be perpendicular to each other.

[0070] Furthermore, the strain gauge 14 does not have to be an existing strain gauge product attached to the guide wire 1. For example, the strain gauge 14 and conductive wiring forming the lead wire may be printed directly on the side of the core wire 13. The printing may be performed, for example, by aerosol jet printing. In this case, a base layer is generated on a portion of the core wire 13 as a base for the printed strain gauge 14. The base layer may be, for example, silicon dioxide or resin. After the strain gauge 14 is formed, the printed pattern may be baked. The strain gauge 14 may be further coated with a resin or the like to an extent that does not affect the strain. Such direct formation makes the strain gauge 14 less likely to peel off from the core wire 13, reducing the possibility of peeling problems during insertion.

[0071] Furthermore, the guide wire 1 is not limited to the structure exemplified above, as long as it is possible to fix the strain gauge 14 and to lead out the signal line.

[0072] In addition, the specific configurations, contents and procedures of the processing operations, etc. shown in the above embodiments can be modified as appropriate without departing from the spirit of the present disclosure. The scope of the present invention includes the scope of the invention described in the claims and its equivalents.

[0073] The present disclosure can be used in guidewires and catheters.

[0074] REFERENCE SIGNS LIST 1 guide wire 11 round cap 12 spring 13 core wire 13a tip portion 13b tapered portion 13c base portion 14, 14a to 14h strain gauge 140 base body 141 resistor 142 terminal 143 connecting wiring 22 control unit 221 CPU 222 memory 2221 parameter setting 3, 4 catheter 5, 6 Y-shaped connector 7, 8 extension tube 9 torquer 100 catheter system B boundary C triple cock H operation mechanism I information processing device P external load R2 to R4 resistance element

Claims

1. A guidewire equipped with a strain gauge, the guidewire having a boundary near its tip where stiffness changes, a first Young's modulus on the base side of the boundary being greater than a second Young's modulus on the tip side of the boundary, and the strain gauge measuring strain related to compression and elongation along the extension direction of the tip side at least on the tip side of the boundary.

2. A guide wire as described in claim 1, wherein the load P associated with compression and extension of the guide wire is expressed as P = E * A * (ΔL / L) based on the length L along the guide wire distal to the boundary, the cross-sectional area A perpendicular to the direction of extension of the guide wire, the magnitude of compression and extension ΔL, and Young's modulus E.

3. The guide wire according to claim 1, wherein the strain gauge does not measure the strain on the base side of the boundary.

4. A guide wire as claimed in claim 1, wherein a core wire is positioned near the tip along the central axis in the extension direction of the guide wire, and a spring is wrapped around the core wire, and the strain gauge is attached to the side of the core wire.

5. The guide wire according to claim 1, wherein the distal end is thinner than the proximal end.

6. A catheter comprising a guidewire according to any one of claims 1 to 5.

7. A guidewire equipped with a strain gauge, the guidewire having a boundary near its tip where rigidity changes, a first Young's modulus on the base side of the boundary being greater than a second Young's modulus on the tip side of the boundary, and the strain gauge measuring strain associated with bending in a direction perpendicular to the extension direction of the tip side at least on the tip side of the boundary.

8. The guide wire according to claim 7, wherein the load P is expressed by P = (E I / (r L)) ε based on the distance L from the boundary to the strain gauge on the tip side, the second moment of area I on the tip side, the radius r of the cross section on the tip side, the strain ε associated with bending, and Young's modulus E.

9. A guide wire according to claim 7, wherein a plurality of said strain gauges are positioned symmetrically with respect to a central axis in the extension direction of said guide wire, and output a difference between the measurement results at positions symmetrical with respect to said central axis.

10. The guide wire according to claim 9, wherein said strain gauges are positioned symmetrically with respect to said central axis along two axes that are orthogonal to each other in a plane perpendicular to said central axis.

11. A guidewire equipped with a strain gauge, the guidewire having a boundary near its tip where stiffness changes, a first modulus of transverse elasticity on the base side of the boundary being greater than a second modulus of transverse elasticity on the tip side of the boundary, and the strain gauge measuring strain associated with torsion on the tip side at least on the tip side of the boundary.

12. The guidewire according to claim 11, wherein the torque T associated with the torsion on the tip side is expressed as T = (G Ip / r) γ based on the polar moment of inertia Ip on the tip side, the radius r of the cross section on the tip side, the shear strain γ, and the second modulus of transverse elasticity G.

13. The guide wire according to claim 11, comprising two strain gauges, the gauge directions of the two strain gauges being inclined at 45 degrees relative to the central axis when viewed from the outside along the radial direction of the central axis on the tip side, and being oriented in directions that differ by 90 degrees from each other.

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