Diagnostic imaging catheter

Abstract

A catheter for diagnostic imaging according to the present disclosure comprises: a sheath; a drive shaft inserted into the sheath; an image sensor fixed to the drive shaft; an outer tube fixed to a proximal end part of the sheath; an inner tube accommodating a proximal end part of the drive shaft and movable within the outer tube together with the drive shaft; and a protective tube fixed to a proximal side of the sheath and that is moved within the inner tube as the inner tube moves within the outer tube, the protective tube allowing the drive shaft to be passed therein. The drive shaft includes a highly rigid section at least in a portion of a shaft base end part that is accommodated within the protective tube in a pushed-in state in which the inner tube is maximally pushed into the outer tube and that is located outside the protective tube in a pulled-out state in which the inner tube is maximally pulled out from the outer tube, the highly rigid section having a higher bending rigidity than a portion that is located within the sheath in the pulled-out state.

Description

Technical Field

[0005]

[0001] The present disclosure relates to a catheter for image diagnosis.

Background Art

[0002] Conventionally, as an example of a catheter for image diagnosis for obtaining tomographic images of blood vessels and the like, an ultrasonic catheter that obtains images by intravascular ultrasound (abbreviated as "IVUS") is known. Patent Document 1 discloses this type of ultrasonic catheter.

[0003] The ultrasonic catheter described in Patent Document 1 includes a catheter sheath inserted into a blood vessel and a drive shaft movable together with an ultrasonic vibrator within this catheter sheath. A connection port and a sheath connector are connected to the proximal side of the catheter sheath described in Patent Document 1. Also, a drive shaft connector is connected to the proximal side of the drive shaft described in Patent Document 1. A guide tube that covers a predetermined portion on the proximal side of the drive shaft described in Patent Document 1 is provided on the distal side of the drive shaft connector described in Patent Document 1.

Prior Art Documents

Patent Documents

[0006] In ultrasound catheters used for diagnostic imaging, such as those described in Patent Document 1, the drive shaft may bend or meander inside the inner and outer tubes. If bending or meandering occurs in the drive shaft, it may bend or break.

[0007] The present disclosure aims to provide an imaging diagnostic catheter capable of suppressing deflection and meandering of the drive shaft inside the inner and outer tubes. [Means for solving the problem]

[0008] An imaging diagnostic catheter as a first aspect of the present disclosure comprises a sheath inserted into a body cavity, a drive shaft inserted within the sheath, an image sensor fixed to the distal end of the drive shaft, an outer tube fixed to the proximal end of the sheath, an inner tube housing the proximal end of the drive shaft and movable within the outer tube together with the drive shaft, and a protective tube fixed to the proximal side of the sheath, which is moved within the inner tube as the inner tube moves within the outer tube, and through which the drive shaft passes, wherein the drive shaft is housed within the protective tube in a pushed-in state where the inner tube is pushed most into the outer tube, and at least a portion of the shaft base end located outside the protective tube in a pulled-out state where the inner tube is pulled most out from the outer tube has a high-rigidity portion with greater bending rigidity than the portion located inside the sheath in the pulled-out state.

[0009] In one embodiment of the present disclosure, the drive shaft is provided with the high-rigidity portion in a region of the base end of the shaft that is at least as long as the length obtained by subtracting the length of the radius of the inner diameter of the inner tube in the shaft axial direction of the drive shaft.

[0010] In one embodiment of the present disclosure, the drive shaft is provided with the high-rigidity portion over the entire area in the axial direction of the shaft base end.

[0011] In one embodiment of the present disclosure, when the shaft base end is the proximal shaft base end, the drive shaft further comprises the high-rigidity portion on at least a portion of the distal shaft base end that is housed in the protective tube in the pushed-in state and the pulled-out state.

[0012] In one embodiment of the present disclosure, the drive shaft does not have the high-rigidity portion in the portion located inside the sheath when it is in the pushed-in state. [Effects of the Invention]

[0013] According to this disclosure, it is possible to provide an imaging diagnostic catheter that can suppress the bending and meandering of the drive shaft inside the inner and outer tubes. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows an ultrasound catheter, which is one embodiment of the diagnostic imaging catheter according to this disclosure, and a diagnostic imaging device connected to an external device. [Figure 2] Figure 1 shows a single ultrasound catheter. [Figure 3A] Figure 2 is a schematic diagram of the operating section of the ultrasound catheter, showing the inner tube in its most extended position, proximal to the outer tube. [Figure 3B] Figure 2 is a schematic diagram of the operating section of the ultrasound catheter, showing the inner tube in its most deeply pushed-in state, distal to the outer tube. [Figure 4] A partial cross-sectional view showing details of a part of the drive shaft of the ultrasonic catheter shown in FIG. 2 and a part of the electrical signal line, and a diagram showing the configuration of the high-rigidity portion of the drive shaft. [Figure 5] A diagram showing a modified example of the high-rigidity portion of the drive shaft shown in FIG. 4. [Figure 6] A diagram showing a modified example of the high-rigidity portion of the drive shaft shown in FIG. 4. [Figure 7] A diagram showing a modified example of the high-rigidity portion of the drive shaft shown in FIG. 4. [Figure 8A] A schematic diagram of the operation section of the ultrasonic catheter in the pulled-out state, and a diagram showing a modified example of the arrangement of the high-rigidity portion of the drive shaft. [Figure 8B] A schematic diagram showing the pushed-out state of the operation section of the ultrasonic catheter shown in FIG. 8A.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the image diagnostic catheter according to the present disclosure will be exemplarily described with reference to the drawings. The same reference numerals are assigned to the common configurations in each figure.

[0016] In the present disclosure, the longitudinal direction of the image diagnostic catheter is described as "longitudinal direction A". In the present disclosure, the side inserted into the living body in the longitudinal direction A of the image diagnostic catheter is described as the "distal side". The proximal side of the image diagnostic catheter that is operated outside the living body in the longitudinal direction A is described as the "proximal side". Also, the direction from the proximal side to the distal side of the image diagnostic catheter may be simply described as "insertion direction A1". The direction from the distal end side to the proximal end side of the image diagnostic catheter may be simply described as "removal direction A2".

[0017] First, an image diagnostic apparatus 100 including an ultrasonic catheter 110 as an embodiment of an image diagnostic catheter according to the present disclosure will be described. FIG. 1 is a diagram showing the image diagnostic apparatus 100. The image diagnostic apparatus 100 includes an ultrasonic catheter 110 and an external device 120. In FIG. 1, a state where the ultrasonic catheter 110 is connected to the external device 120 is shown. Hereinafter, in this specification, the ultrasonic catheter 110 will be exemplified and described as an image diagnostic catheter. However, the image diagnostic catheter according to the present disclosure is not limited to the ultrasonic catheter 110 shown in this embodiment. The image diagnostic catheter may be, for example, a catheter that enables optical coherence tomography (abbreviated as "OCT"), near infrared spectroscopy (abbreviated as "NIRS"), or the like. In such a case, the image diagnostic catheter may be configured to include an optical sensor as an image sensor instead of or in addition to the ultrasonic sensor 60 described later.

[0018] <Ultrasonic catheter 110> FIG. 2 is a diagram showing the ultrasonic catheter 110 alone shown in FIG. 1. The ultrasonic catheter 110 is applied to intravascular ultrasound diagnosis (abbreviated as "IVUS"). As shown in FIG. 1, the ultrasonic catheter 110 is driven by being connected to the external device 120. More specifically, the ultrasonic catheter 110 of the present embodiment is connected to the drive unit 120a of the external device 120.

[0019] As shown in FIGS. 1 and 2, the ultrasonic catheter 110 includes an insertion portion 110a and an operation portion 110b. The insertion portion 110a is a portion of the ultrasonic catheter 110 that is inserted into and used in the living body. The operation portion 110b is a portion of the ultrasonic catheter 110 that is operated outside the living body while the insertion portion 110a is inserted into the living body. In the ultrasonic catheter 110 of the present embodiment, the portion distal to the distal connector 42 described later is the insertion portion 110a, and the portion proximal to the distal connector 42 is the operation portion 110b.

[0020] As shown in Figures 1 and 2, the insertion section 110a comprises the distal portion of the ultrasonic probe 10 and the sheath 20. As will be described in detail later, the distal portion of the ultrasonic probe 10 included in the insertion section 110a consists of the ultrasonic sensor 60, the distal portion of the drive shaft 13, and the distal portion of the electrical signal line 14 (see Figure 4).

[0021] The operating unit 110b can move the drive shaft 13 within the sheath 20 in the longitudinal direction of the sheath 20 (the same direction as longitudinal direction A). As shown in Figures 1 and 2, the operating unit 110b comprises the proximal portion of the ultrasonic probe 10, an inner tube 30, an outer tube 40, and a protective tube 50. As will be described in detail later, the proximal portion of the ultrasonic probe 10 included in the operating unit 110b consists of the proximal portion of the drive shaft 13 and the proximal portion of the electrical signal line 14 (see Figure 4).

[0022] The inner tube 30 holds the proximal end of the ultrasonic probe 10 (hereinafter, "proximal end" will be simply referred to as "proximal end"). The outer tube 40 holds the proximal end of the sheath 20. As will be described in detail later, the ultrasonic probe 10 can move within the sheath 20 in the longitudinal direction A by moving the inner tube 30 within the outer tube 40 in the central axis direction (the same direction as the longitudinal direction A).

[0023] [Ultrasonic probe 10] Figures 3A and 3B are schematic diagrams of the operating section 110b of the ultrasound catheter 110. Figure 3A shows the extended state, where the inner tube 30 is most extended proximally from the outer tube 40. Figure 3B shows the pushed-in state, where the inner tube 30 is most pushed distally into the outer tube 40. Hereafter, the state shown in Figure 3A may be simply referred to as the "extended state," and the state shown in Figure 3B may be simply referred to as the "pushed-in state." Figure 4 is a partial cross-sectional view showing details of a part of the drive shaft 13 and a part of the electrical signal line 14 of the ultrasound catheter 110.

[0024] As shown in Figure 2, the ultrasonic probe 10 comprises an ultrasonic sensor 60 as an image sensor, a drive shaft 13, and an electrical signal line 14 (see Figure 4) extending within the drive shaft 13. The ultrasonic sensor 60 comprises an ultrasonic transducer and a housing.

[0025] As shown in Figure 2, the ultrasonic sensor 60 is fixed to the distal end of the drive shaft 13 (hereinafter, the distal end will be simply referred to as the "distal end"). The ultrasonic transducer of the ultrasonic sensor 60 includes a piezoelectric element. The piezoelectric element consists of a flat piezoelectric body and electrodes stacked on this piezoelectric body. The ultrasonic transducer can transmit and receive ultrasonic waves.

[0026] The housing of the ultrasonic sensor 60 supports the ultrasonic transducer. The proximal side of the housing is connected to the drive shaft 13. The housing only needs to be integrated with the drive shaft 13. Therefore, the housing may be directly connected to the drive shaft 13 by adhesive or the like, or it may be indirectly connected to the drive shaft 13 via a connector or the like.

[0027] As shown in Figure 2, the drive shaft 13 is inserted into the sheath 20. The drive shaft 13 is made of a flexible tube. As shown in Figure 4, electrical signal lines 14 connected to the ultrasonic transducer of the ultrasonic sensor 60 are arranged inside the drive shaft 13. The drive shaft 13 is made of, for example, a multilayer coil with different winding directions around the axis. As will be described in detail later, the drive shaft 13 of this embodiment is made of three layers of coil (see Figure 4, etc.). Examples of coil materials include stainless steel and Ni-Ti (nickel-titanium) alloy. By using such a drive shaft 13, even if the two electrical signal lines 14 are made of double-helix twisted-pair cables, the shielding performance can be enhanced and the influence of noise generated from the electrical signal lines 14 can be reduced.

[0028] As shown in Figures 2 to 4, the drive shaft 13 extends through the inside of the sheath 20, inner tube 30, outer tube 40, and protective tube 50. As described above, the distal end of the drive shaft 13 is connected to the housing of the ultrasonic sensor 60. The proximal end of the drive shaft 13 is held by the hub 32, which will be described later and constitutes the proximal end of the inner tube 30. In other words, the drive shaft 13 extends in the longitudinal direction A from the distal end of the insertion portion 110a to the proximal end of the operating portion 110b.

[0029] As shown in Figure 4, the electrical signal wire 14 extends within the drive shaft 13. The electrical signal wire 14 electrically connects the ultrasonic transducer of the ultrasonic sensor 60 (see Figure 2) to the external device 120 (see Figure 1). In other words, like the drive shaft 13, the electrical signal wire 14 extends in the longitudinal direction A from the distal end of the insertion section 110a to the proximal end of the operating section 110b. Multiple electrical signal wires 14 (two in this embodiment) are provided, and each electrical signal wire 14 is connected to the electrode of the ultrasonic transducer of the ultrasonic sensor 60. Multiple electrical signal wires 14 are, for example, made of a twisted pair cable in which two electrical signal wires 14 are twisted together. Each electrical signal wire 14 can be a flexible, thin wire member with an outer diameter greater than 0 mm and less than or equal to 0.1 mm. Each electrical signal wire 14 can be made of, for example, a conductor and a covering material formed of an insulating material that covers the conductor.

[0030] [Sheath 20] The sheath 20 is inserted into a body cavity such as a blood vessel. As shown in Figure 2, the sheath 20 comprises a main body portion 20a and a guidewire insertion portion 20b. A first hollow portion is partitioned inside the main body portion 20a. A second hollow portion is partitioned in the guidewire insertion portion 20b. The ultrasonic probe 10 is housed in the first hollow portion of the main body portion 20a. The ultrasonic probe 10 can move forward and backward in the longitudinal direction A within the first hollow portion. A guidewire can be inserted into the second hollow portion of the guidewire insertion portion 20b. As shown in Figure 2, in this embodiment, the tubular guidewire insertion portion 20b is adjacent to the distal end of the tubular main body portion 20a so as to be parallel to each other. The main body portion 20a and the guidewire insertion portion 20b may be formed by joining different tubular members by heat fusion or the like.

[0031] The sheath 20 is formed from a flexible material, and the material is not particularly limited. Examples of constituent materials include various thermoplastic elastomers such as polyethylene, styrene, polyolefin, polyurethane, polyester, polyamide, polyimide, polybutadiene, trans polyisoprene, fluororubber, and chlorinated polyethylene. Polymer alloys, polymer blends, laminates, etc., which are combinations of one or more of these materials, can also be used.

[0032] The main body portion 20a may have a reinforcing portion at its proximal end, which is reinforced with a highly rigid material. The reinforcing portion may be formed, for example, by arranging a reinforcing material, which is made of metal wires such as stainless steel braided in a mesh pattern, on a flexible tubular member such as resin. The tubular member may be formed, for example, from the constituent material of the sheath 20 described above.

[0033] [Inner tube 30 and outer tube 40] The inner tube 30 houses the proximal end of the drive shaft 13 and is movable within the outer tube 40 together with the drive shaft 13. As shown in Figures 1, 2, 3A, and 3B, the inner tube 30 comprises an inner tube body 31 and a hub 32. The inner tube body 31 is inserted into the outer tube 40 so as to be movable back and forth. The hub 32 is connected to the proximal side of the inner tube body 31.

[0034] As shown in Figures 1, 2, 3A, and 3B, the outer tube 40 is fixed to the proximal end of the sheath 20. In this embodiment, the outer tube 40 comprises an outer tube body 41, a distal connector 42, and a proximal connector 43. The outer tube body 41 is located radially outside the inner tube body 31, and the inner tube body 31 moves back and forth inside the outer tube body 41. The distal connector 42 connects the proximal end of the main body portion 20a of the sheath 20 to the distal end of the outer tube body 41. The proximal connector 43 is fixed to the proximal end of the outer tube body 41.

[0035] The drive shaft 13 and electrical signal line 14 of the ultrasonic probe 10 described above extend to the main body 20a of the sheath 20, the outer tube 40 connected to the proximal side of the main body 20a, and the hub 32 which constitutes the proximal end of the inner tube 30, part of which is inserted into the outer tube 40.

[0036] The ultrasonic probe 10 and inner tube 30 described above are connected to each other so that they move integrally in the longitudinal direction A. Therefore, for example, when the inner tube 30 is pushed in the insertion direction A1, as shown in Figure 3B, the inner tube 30 is pushed into the outer tube 40 in the insertion direction A1. When the inner tube 30 is pushed into the outer tube 40 in the insertion direction A1, the ultrasonic probe 10 connected to the inner tube 30 moves in the insertion direction A1 within the main body portion 20a of the sheath 20. Conversely, when the inner tube 30 is pulled in the withdrawal direction A2, as shown in Figure 3A, the inner tube 30 is pulled out from the outer tube 40 in the withdrawal direction A2. When the inner tube 30 is pulled out from the outer tube 40 in the withdrawal direction A2, the ultrasonic probe 10 connected to the inner tube 30 moves in the withdrawal direction A2 within the main body portion 20a of the sheath 20.

[0037] As shown in Figure 3B, when the inner tube 30 is pushed in as far as it can go in the insertion direction A1, the distal end of the inner tube 30 reaches near the distal connector 42 of the outer tube 40. At this time, the ultrasonic sensor 60 of the ultrasonic probe 10 is located near the distal end of the main body portion 20a of the sheath 20.

[0038] The inner tube 30 and the outer tube 40 are provided with a pull-out stopper to prevent the inner tube 30 from falling out of the outer tube 40 when the inner tube 30 is pulled out of the outer tube 40 in the pull-out direction A2. The pull-out stopper in this embodiment is composed of the distal end 31a of the inner tube body 31 of the inner tube 30 and the abutment wall portion 43b of the proximal connector 43 of the outer tube 40. The distal end 31a of the inner tube body 31 of the inner tube 30 has an annular projection that protrudes radially outward. This annular projection of the distal end 31a abuts against the abutment wall portion 43b of the proximal connector 43, thereby restricting the movement of the inner tube 30 in the pull-out direction A2 relative to the outer tube 40. In other words, in this embodiment, the state in which the inner tube 30 is pulled out to its fullest extent in the withdrawal direction A2 from the outer tube 40 (see Figure 3A) means that the annular protrusion at the distal end 31a of the inner tube body 31 of the inner tube 30 is in contact with the abutment wall 43b of the proximal connector 43 of the outer tube 40.

[0039] Furthermore, the inner tube 30 and the outer tube 40 are provided with a push-in side retaining stopper to prevent the inner tube 30 from falling out of the outer tube 40 when the inner tube 30 is pushed into the outer tube 40 in the insertion direction A1. The push-in side retaining stopper in this embodiment is composed of the distal end face 32a of the hub 32 of the inner tube 30 and the proximal end face 43a of the proximal connector 43 of the outer tube 40. The distal end face 32a of the hub 32 of the inner tube 30 abuts against the proximal end face 43a of the proximal connector 43 of the outer tube 40, thereby restricting the movement of the inner tube 30 in the insertion direction A1 relative to the outer tube 40. In other words, in this embodiment, the pushed-in state (see Figure 3B) in which the inner tube 30 is pushed the furthest into the outer tube 40 in the insertion direction A1 means that the distal end face 32a of the hub 32 of the inner tube 30 is in contact with the proximal end face 43a of the proximal connector 43 of the outer tube 40.

[0040] However, the pull-out and push-in stoppers provided on the inner tube 30 and outer tube 40 are not limited to the configuration described above. Any configuration that prevents the inner tube 30 from falling out of the outer tube 40 on the pull-out side and on the push-in side is not particularly limited.

[0041] A connector is provided at the proximal end of the hub 32 of the inner tube 30, which is mechanically and electrically connected to the external device 120 (see Figure 1). In other words, the ultrasonic catheter 110 is mechanically and electrically connected to the external device 120 by the connector provided on the hub 32 of the inner tube 30. More specifically, the electrical signal line 14 of the ultrasonic probe 10 extends from the ultrasonic transducer of the ultrasonic sensor 60 to the connector on the hub 32 of the inner tube 30, and the ultrasonic transducer of the ultrasonic sensor 60 and the external device 120 are electrically connected when the connector on the hub 32 is connected to the external device 120. The received signal from the ultrasonic transducer is transmitted to the external device 120 via the connector on the hub 32, where it is processed and displayed as an image.

[0042] [Protection tube 50] As shown in Figures 3A and 3B, the protective tube 50 is fixed to the proximal side of the sheath 20. More specifically, the protective tube 50 is fixed to the proximal end of the sheath 20 together with the outer tube body 41 of the outer tube 40 via the distal connector 42. In other words, the protective tube 50 in this embodiment is directly fixed to the outer tube 40. The distal end of the protective tube 50 in this embodiment is fixed to the inner wall of the hollow portion of the distal connector 42 through which the drive shaft 13 passes.

[0043] Furthermore, the protective tube 50 moves within the inner tube 30 as the inner tube 30 moves within the outer tube 40, allowing the drive shaft 13 to pass through its interior. As shown in Figures 3A and 3B, the protective tube 50 in this embodiment extends within the outer tube 40 in the direction of the central axis of the outer tube 40 (the same direction as the longitudinal direction A). The protective tube 50 is arranged concentrically with the outer tube 40 within the outer tube 40. The proximal end of the protective tube 50 is an open free end. The drive shaft 13 extends within the outer tube 40 and within the protective tube 50. As the inner tube 30 and the outer tube 40 move relative to each other in the longitudinal direction A, the protective tube 50 moves in the annular space between the inner tube 30 and the drive shaft 13.

[0044] More specifically, when transitioning from the pulled-out state shown in Figure 3A to the pushed-in state shown in Figure 3B, the protective tube 50 moves in the withdrawal direction A2 relative to the inner tube 30 and is pushed into the inner tube 30. Conversely, when transitioning from the pushed-in state shown in Figure 3B to the pulled-out state shown in Figure 3A, the protective tube 50 moves in the insertion direction A1 relative to the inner tube 30 and is pulled out from inside the inner tube 30. In this way, the protective tube 50 is pushed in and pulled out relative to the inner tube 30. The drive shaft 13 is prone to bending and meandering when pushed in the insertion direction A1 due to friction between, for example, the ultrasonic sensor 60 and the drive shaft 13 and the sheath 20. By providing the protective tube 50 described above, bending and meandering of the drive shaft 13 inside the outer tube 40 can be suppressed compared to a configuration without the protective tube 50. As a result, bending and breakage of the drive shaft 13 inside the outer tube 40 can be suppressed.

[0045] As shown in Figures 3A and 3B, the free end, which is the proximal end of the protective tube 50 in this embodiment, is located inside the inner tube 30 not only when the inner tube 30 and outer tube 40 are pushed in (see Figure 3B), but also when they are pulled out (see Figure 3A). In other words, the protective tube 50 in this embodiment is positioned so that its proximal end is always located inside the inner tube 30. With this configuration, the portion of the drive shaft 13 that is inside the outer tube 40 but not housed in the inner tube 30 can be housed inside the protective tube 50. In other words, even the portion of the drive shaft 13 that is prone to bending and meandering inside the outer tube 40 can be protected from bending and meandering by the protective tube 50.

[0046] As shown in Figures 3A and 3B, the protective tube 50 in this embodiment extends from the distal end of the outer tube 40, beyond the proximal end of the outer tube 40, to the outside of the outer tube 40, but the configuration is not limited to this.

[0047] In this embodiment, the protective tube 50 is fixed to the outer tube 40, but for example, the protective tube 50 itself may not be an independent component but rather a part that is integrally connected from the proximal end of the sheath 20.

[0048] The protective tube 50 may be formed, for example, as a loosely wound metal coil. This allows saline solution to flow in through the gaps in the coil during priming, making it less likely for air to remain inside the outer tube 40. Alternatively, the protective tube 50 may be made of a fluororesin such as PTFE instead of metal. Furthermore, the protective tube 50 may be a tube with at least one slit or hole formed in it, rather than a loosely wound coil. In addition, the protective tube 50 may be a composite tube, such as a metal pipe with holes on its side and a resin tube joined to this metal pipe.

[0049] <External device 120> As shown in Figure 1, the external device 120 includes a motor 121, which is a power source for rotating the drive shaft 13 (see Figure 2, etc.), and a motor 122, which is a power source for moving the drive shaft 13 in the longitudinal direction A. The rotational motion of the motor 122 is converted into axial motion by a ball screw 123 connected to the motor 122.

[0050] More specifically, the external device 120 of this embodiment comprises a drive unit 120a, a control device 120b electrically connected to the drive unit 120a by wire or wireless, and a monitor 120c capable of displaying an image generated by the control device 120b based on a received signal received from the ultrasound catheter 110. The motors 121, 122, and ball screw 123 described above in this embodiment are provided on the drive unit 120a. The operation of the drive unit 120a is controlled by the control device 120b. The control device 120b can be configured with a processor including a CPU and memory.

[0051] The external device 120 is not limited to the configuration shown in this embodiment, and may further include, for example, an external input unit such as a keyboard.

[0052] The details of the high-rigidity portion 70 of the drive shaft 13 in the ultrasonic catheter 110 will be described below with reference to Figures 3A, 3B, and 4.

[0053] The drive shaft 13 is equipped with a high-rigidity section 70. The high-rigidity section 70 is provided at the proximal end of the drive shaft 13. Specifically, the drive shaft 13 is housed in the protective tube 50 when the inner tube 30 is pushed most deeply into the outer tube 40 (see Figure 3B), and has a shaft base end 13a that is located outside the protective tube 50 when the inner tube 30 is pulled out most deeply from the outer tube 40 (see Figure 3A). The drive shaft 13 is equipped with a high-rigidity section 70 in at least a portion of this shaft base end 13a. The high-rigidity section 70 has greater bending rigidity than the shaft body section 13b, which is the part of the drive shaft 13 that is located inside the sheath 20 when it is pulled out (see Figure 3A). This "bending rigidity" can be determined, for example, by holding a test piece of a predetermined length in a cantilevered manner and examining the relationship between the load applied to the free end and the deformation.

[0054] In this way, by providing a high-rigidity portion 70 to at least a part of the shaft base end 13a of the drive shaft 13, deflection and meandering at the shaft base end 13a located outside the protective tube 50 when extended (see Figure 3A) can be suppressed.

[0055] Here, as shown in Figure 3A, in the extended state (see Figure 3A), the shaft base end 13a is located outside the protective tube 50, but is still located inside the inner tube 30. Therefore, the bending and meandering of the shaft base end 13a when the inner tube 30 is pushed into the outer tube 40 is suppressed by the inner tube 30. However, the drive shaft 13 is housed so as to be rotatable within the inner tube 30. Therefore, a gap is provided between the shaft base end 13a of the drive shaft 13 and the inner tube 30 that surrounds this shaft base end 13a. In addition, a gap may be provided from the viewpoint of ensuring a flow path during priming. In other words, even the portion of the drive shaft 13 located inside the inner tube 30 may bend or meander due to the aforementioned gap. In response to this, by providing a high-rigidity section 70 to at least a part of the shaft base end 13a, the aforementioned bending and meandering at the shaft base end 13a can be suppressed. As a result, bending and breakage of the shaft base end 13a can be suppressed.

[0056] Figure 4 shows the high-rigidity section 70 of the drive shaft 13 in this embodiment. More specifically, Figure 4 shows the distal end of the high-rigidity section 70 of the drive shaft 13 in this embodiment. As shown in Figure 4, the high-rigidity section 70 in this embodiment comprises three coil sections 71 with different winding directions, and a cylindrical body 72 that covers the radially outer side of these three coil sections 71. The shaft body 13b (see Figure 3A), located inside the sheath 20 in the extended state (Figure 3A), is composed only of the three coil sections 71. In other words, the high-rigidity section 70 in this embodiment is constructed by surrounding the three coil sections 71, which are integrally connected from the shaft body 13b, with the cylindrical body 72.

[0057] The cylindrical body 72 can be made of, for example, a resin tube or a metal pipe. The deflection and meandering of the coil portion 71 housed inside the cylindrical body 72 are limited by contact with the inner surface of the cylindrical body 72. The proximal end of the cylindrical body 72 in this embodiment is fitted into the hollow portion of the hub 32 (see Figure 3A, etc.) of the inner tube 30. In other words, the proximal end of the cylindrical body 72 in this embodiment is fixed by being sandwiched between the inner wall of the hollow portion of the hub 32, with the drive shaft 13 housed inside it. That is, the proximal end of the drive shaft 13 and the proximal end of the cylindrical body 72 are fixed to the hub 32 of the inner tube 30.

[0058] As described above, the high-rigidity portion 70 is housed within the protective tube 50 when pushed in (see Figure 3B) and is located outside the protective tube 50 when pulled out (see Figure 3A). In other words, the cylindrical body 72 in this embodiment is provided on at least a portion of the shaft base end 13a. However, as in this embodiment, it is preferable that the high-rigidity portion 70 be provided in a region of the shaft base end 13a that is at least the length obtained by subtracting the radius of the inner diameter of the inner tube 30 (see the symbol "r" in Figure 3A) in the shaft axis direction (same direction as longitudinal direction A) of the drive shaft 13. In other words, in this embodiment, the cylindrical body 72 is provided in a region of the shaft base end 13a that is at least the length obtained by subtracting the radius of the inner diameter of the inner tube 30 (see the symbol "r" in Figure 3A) in the shaft axis direction of the drive shaft 13. By doing so, deflection and meandering of the shaft base end 13a can be further suppressed. As a result, bending and breakage of the shaft base end 13a can be further suppressed. "Inner diameter of inner tube" refers to the inner diameter of the portion of the inner tube that is inserted into the outer tube, and in this embodiment, it refers to the inner diameter r of the inner tube body 31 of the inner tube 30.

[0059] Furthermore, as in this embodiment, it is more preferable that the drive shaft 13 is provided with a high-rigidity portion 70 over the entire length of the shaft base end 13a in the shaft axial direction. In other words, in this embodiment, the cylindrical body 72 is provided over the entire length of the shaft base end 13a in the shaft axial direction. By doing so, the bending and meandering of the shaft base end 13a can be further suppressed. As a result, bending and breakage of the shaft base end 13a can be further suppressed.

[0060] Furthermore, when the shaft base end 13a described above is referred to as the "proximal shaft base end 13a," it is preferable that, as in this embodiment, the drive shaft 13 further includes a high-rigidity portion 70 in at least a part of the distal shaft base end 13c, which is housed within the protective tube 50 in the pushed-in state (see Figure 3B) and the pulled-out state (see Figure 3A). In other words, in this embodiment, the cylindrical body 72 is provided not only on the proximal shaft base end 13a but also on the distal shaft base end 13c. More specifically, the cylindrical body 72 in this embodiment is provided over the entire shaft axial region of the proximal shaft base end 13a and over a portion of the distal shaft base end 13c that is continuous with the distal side of the proximal shaft base end 13a. In other words, the distal end of the cylindrical body 72 in this embodiment is located within the protective tube 50 even in the pulled-out state (see Figure 3A). In this way, when transitioning from the extended state (see Figure 3A) to the pushed-in state (see Figure 3B), the distal end of the high-rigidity section 70 does not catch on the free end, which is the proximal end of the protective tube 50. Therefore, the bending and meandering of the proximal shaft base end 13a can be further suppressed. As a result, bending and fracture of the proximal shaft base end 13a can be further suppressed.

[0061] Furthermore, in this embodiment, the drive shaft 13 does not have a high-rigidity section 70 in the portion located inside the sheath 20 when it is in the pressed-in state (see Figure 3B). In other words, the high-rigidity section 70 is formed in a position that does not enter the sheath 20 when it is in the pressed-in state (see Figure 3B). More specifically, the distal end of the high-rigidity section 70 of the drive shaft 13 in this embodiment is located inside the outer tube 40 when it is in the pressed-in state (see Figure 3B). By doing so, even if the bending rigidity of the high-rigidity section 70 is higher than that of the sheath 20, it is possible to prevent the high-rigidity section 70 from entering the sheath 20 and causing the orientation of the sheath 20 to change to conform to the orientation of the high-rigidity section 70. As a result, positional fluctuations of the ultrasonic sensor 60 inside the sheath 20 can be suppressed. In addition, bending of the sheath 20 at the distal end of the high-rigidity section 70 can be suppressed. In other words, in the ultrasonic catheter 110 of this embodiment, the bending rigidity of the high-rigidity portion 70 of the drive shaft 13 may be higher than the bending rigidity of the sheath 20.

[0062] As described above, the high-rigidity section 70 of this embodiment is composed of a three-layer coil section 71 and a cylindrical body 72, but is not limited to this configuration. Figures 5 to 7 show modified examples of the high-rigidity section 70.

[0063] The high-rigidity section 70 shown in Figure 5 comprises a three-layer coil section 71 and a laminated reinforcing section 73 joined to the outer circumferential surface of the coil section 71 and laminated on the outer circumferential surface of the coil section 71. Thus, the high-rigidity section 70 may include a laminated reinforcing section 73 joined to the outer circumferential surface of the coil section 71, in place of or in addition to the cylindrical body 72 (see Figure 4) described above. The laminated reinforcing section 73 can be made of, for example, wax or various resins. The three-layer coil section 71 gains strength and bending rigidity when reinforced by the laminated reinforcing section 73. The method of joining the laminated reinforcing section 73 to the outer circumferential surface of the coil section 71 is not particularly limited. The laminated reinforcing section 73 can be joined to the outer circumferential surface of the coil section 71 by, for example, adhesive, welding, coating, etc.

[0064] The high-rigidity section 70 shown in Figure 6 comprises a three-layer coil section 71 and a core member 74 inserted inside the coil section 71. Thus, the high-rigidity section 70 may include a core member 74 inserted inside the coil section 71, in place of or in addition to the cylindrical body 72 (see Figure 4) and laminated reinforcement section 73 (see Figure 5) described above. The core member 74 can be made of, for example, metal or resin. The deflection and meandering of the coil section 71 are limited by contact with the outer surface of the core member 74.

[0065] The high-rigidity section 70 shown in Figure 7 is composed of three layers of coil section 75. However, each coil in the coil section 75 constituting the high-rigidity section 70 shown in Figure 7 has a larger cross-sectional dimension compared to each coil in the three layers of coil section 71 located distal to it. In the example shown in Figure 7, the three layers of coil section 71 located distally and the three layers of coil section 75, which constitutes the high-rigidity section 70 located proximal to it, are joined by a joint 76. The joint 76 is not particularly limited as long as it is a configuration that joins the coil section 71 and the coil section 75, such as a weld or adhesive.

[0066] In Figure 7, differences in bending stiffness are achieved by varying the cross-sectional dimensions of the coils. However, differences in bending stiffness may also be achieved by utilizing other coil configurations, such as coil pitch or coil cross-sectional shape.

[0067] Furthermore, the high-rigidity section 70 shown in Figure 7 may further comprise at least one of the following: a cylindrical body 72 (see Figure 4), a laminated reinforcing section 73 (see Figure 5), and a core member 74 (see Figure 6).

[0068] Thus, the configuration of the high-rigidity section 70 is not particularly limited, as long as it has a higher bending rigidity than the shaft body section 13b, which is located inside the sheath 20 when extended (see Figure 3A).

[0069] The imaging diagnostic catheter according to this disclosure is not limited to the specific configurations shown in the embodiments and modifications described above, and various modifications, changes, and combinations are possible as long as they do not deviate from the scope of the claims. For example, Figures 3A and 3B show a configuration in which a single high-rigidity section 70 is provided in the shaft axis direction at the proximal shaft base end 13a, but the catheter is not limited to this configuration. As shown in Figures 8A and 8B, a configuration in which a plurality of high-rigidity sections 70 are intermittently arranged in the shaft axis direction at the proximal shaft base end 13a may be provided. However, as in the embodiments described above, it is preferable that the high-rigidity section 70 extends distally from inside the hub 32 of the inner tube 30 and, in the pulled-out state (see Figure 3A), reaches near the proximal end of the protective tube 50, or to a position inside the protective tube 50 as in the embodiments described above. By doing so, deflection and meandering of the proximal shaft base end 13a can be suppressed more reliably. [Industrial applicability]

[0070] This disclosure relates to a catheter for diagnostic imaging. [Explanation of Symbols]

[0071] 10: Ultrasonic probe 13: Drive shaft 13a: Proximal shaft base end (shaft base end) 13b: Shaft body 13c: Distal shaft proximal end 14: Electrical signal lines 20: Sheath 20a: Main body 20b: Guide wire insertion section 30: Inner tube 31: Inner tube body 31a: Distal end of the inner tube body 32: Hub 32a: Distal end face of the hub 40:Outer tube 41:Outer tube body 42: Distal connector 43: Proximal connector 43a: Proximal end face 43b: Butt wall section 50: Protection tube 60: Ultrasonic sensor (an example of an image sensor) 70: High rigidity part 71: Coil section 72: Cylinder 73: Laminated reinforcement section 74: Core material 75: Coil section 76: Joint 100: Diagnostic imaging equipment 110: Ultrasound catheter (an example of a catheter used for diagnostic imaging) 110a: Insertion part 110b: Operation unit 120: External device 120a: Drive unit 120b: Control device 120c: Monitor 121, 122: Motor 123: Ball screw A: Longitudinal direction of the imaging catheter (longitudinal direction of the sheath) A1: Insertion direction A2: Removal direction r: Radius of the inner diameter of the inner tube

Claims

1. A sheath that is inserted into the body cavity, The drive shaft inserted into the sheath, An image sensor fixed to the distal end of the drive shaft, The outer tube is fixed to the proximal end of the sheath, An inner tube that houses the proximal end of the drive shaft and is movable within the outer tube together with the drive shaft, A protective tube is fixed to the proximal side of the sheath, moves within the inner tube as the inner tube moves within the outer tube, and passes the drive shaft through it, The drive shaft is housed in the protective tube in a compressed state where the inner tube is pushed most deeply into the outer tube, and at least a portion of the base end of the shaft, where the inner tube is located outside the protective tube in a pulled-out state where it is pulled most deeply out from the outer tube, is provided with a high-rigidity portion that has greater bending rigidity than the portion located inside the sheath in the pulled-out state. The aforementioned high-rigidity section is formed by the fact that the periphery of the multi-layered coil section is surrounded by a cylindrical body. A diagnostic imaging catheter, wherein the portion of the drive shaft located within the sheath in the extended state is configured such that the periphery of the multilayer coil portion is not surrounded by the cylindrical body.

2. The imaging diagnostic catheter according to claim 1, wherein the drive shaft has the high-rigidity portion in a region of the base end of the shaft that is at least the length obtained by subtracting the length of the radius of the inner diameter of the inner tube in the shaft axial direction of the drive shaft.

3. The image diagnostic catheter according to claim 2, wherein the drive shaft is provided with the high-rigidity portion over the entire area in the axial direction of the shaft at the base end of the shaft.

4. The imaging diagnostic catheter according to any one of claims 1 to 3, wherein, when the shaft proximal end is the proximal shaft proximal end, the drive shaft further comprises the high-rigidity portion in at least a portion of the distal shaft proximal end that is housed in the protective tube in the pushed-in state and the pulled-out state.

5. The imaging diagnostic catheter according to any one of claims 1 to 3, wherein the drive shaft does not have the high-rigidity portion in the portion located inside the sheath when in the pushed-in state.

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