CATHETER ASSEMBLY

A catheter assembly includes a catheter including an expandable and contractible tube provided with a lumen and a contact portion provided in a distal end portion of the tube. A stylet can be inserted in the lumen to make the tube expand in the longitudinal direction by coming into contact with the contact portion. A straight connector is provided on a proximal end side of the catheter which can be coupled to the stylet. The connector includes a male screw portion that is engageable with the stylet. The stylet includes a stylet hub disposed on the proximal end side of the catheter and a coupling member that couples the style hub and the straight connector to each other and is engageable with the male screw portion by rotating independently of the stylet hub.

BACKGROUND OF THE INVENTION

The present invention relates to a catheter assembly including a blood transmission hole for transmitting blood to a living body.

Conventionally, treatment using percutaneous cardiopulmonary support (PCPS) has been performed for cardiopulmonary resuscitation, circulatory support, and respiratory support in emergency treatment. The percutaneous cardiopulmonary support is a technique for temporarily assisting or substituting for a cardiopulmonary function using an extracorporeal circulatory device. The extracorporeal circulatory device is also used for open heart surgery.

The extracorporeal circulatory device includes an extracorporeal circulation circuit including a centrifugal pump, an artificial lung, a blood removal channel, a blood transmission channel, and the like, performs gas exchange for the blood that has been removed, and then transmits the resultant blood into the blood transmission channel. In this context, U.S. Pat. No. 7,748,275B2 describes an example of a circulation circuit of an extracorporeal circulatory device.

In such a circulation circuit, a catheter is used that includes a blood transmission hole (outflow hole) for transmitting the blood after gas exchange to a desired position of a living body. The catheter is placed at a predetermined position in the living body to be used for extracorporeal circulation. In addition, a catheter that can expand and contract in a radial direction and axial direction (longitudinal direction) to be easily arranged at the predetermined position is used. Furthermore, the catheter may be used together with a medical device such as a stylet for restricting the shape of the catheter moving in a lumen of a living body. The stylet has a function of contracting the catheter in the radial direction, by applying tensile force in the axial direction of the catheter to expand the catheter when the catheter is inserted in the lumen of the living body. The catheter and stylet may be fixed through engagement between spiral shaped members such as a screw.

Under this condition, an attempt to engage the spiral shaped members of the catheter and the stylet through rotation of the stylet in a state where the tensile force is applied by the stylet in the longitudinal direction of the catheter, involves a risk that a distal end of the catheter might rotate to follow the stylet to be twisted. When such twisting occurs, a load due to the rotation of the catheter continues to be applied, resulting in potential deterioration of insertability of the catheter for percutaneous insertion.

SUMMARY OF THE INVENTION

In view of this, an object of the present invention is to provide a catheter assembly with which twisting occurring in a catheter when the catheter and a stylet are connected to each other is prevented or suppressed, so that deterioration of the insertability of the catheter for percutaneous insertion is prevented or suppressed.

A catheter assembly achieving the above object may include: a catheter including a tube that is formed to have an elongated shape, is provided with a lumen in which blood is flowable, and is expandable and contractible, and to have a first contact portion configured to be contacted in a manner that enables the tube to expand in a longitudinal direction, the first contact portion being provided in a distal end portion of the tube; a stylet that is configured to be capable of being inserted in the lumen, and enables the tube to expand in the longitudinal direction by coming into contact with the first contact portion; and a connector capable of coupling with the stylet, the connector being mounted on a proximal end side of the tube, wherein the connector includes a first engagement portion engageable with the stylet, and wherein the stylet includes a hub disposed on the proximal end side of the catheter and a coupling member that couples the hub and the connector to each other, the coupling member being engageable with the first engagement portion by rotating independently of the hub.

In the catheter assembly with the configuration described above, the stylet is configured to receive the coupling member which is engageable with the first engagement portion by rotating independently of the hub. With this configuration, even when the coupling member of the stylet rotates, no or almost no rotation is transmitted to the hub of the stylet. Thus, twisting of the catheter can be prevented or suppressed. Thus, deterioration of the insertability of the catheter for percutaneous insertion can be prevented or suppressed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.FIG. 1is a diagram illustrating an example of an extracorporeal circulatory device employing a catheter provided in a catheter assembly according to an embodiment of the present invention. The extracorporeal circulatory device can be used, for example, in percutaneous cardiopulmonary support (PCPS), which temporarily assists or substitutes for heart and lung functions until the cardiac function of a patient with a weakened heart is restored.

An extracorporeal circulatory device1can be used for veno-arterial (VA) procedures. In the venous-arterial procedure (VA), a pump is actuated to remove blood from a patient's vein (for example, a large vein), an artificial lung2exchanges gas in the blood to oxygenate the blood, and the resultant blood is returned to an artery (for example, aorta). As described above, the extracorporeal circulatory device1can be used as a device for assisting the heart and lungs of the patient. Hereinafter, the procedure of removing blood from a patient, performing a predetermined treatment on the blood outside the body, and then transmitting the blood back into the patient's body is referred to as “extracorporeal circulation”.

As illustrated inFIG. 1, the extracorporeal circulatory device1includes a circulation circuit for circulating blood. The circulation circuit includes the artificial lung2, a centrifugal pump3, a drive motor4serving as a driving unit for driving the centrifugal pump3, a venous catheter (percutaneous catheter for blood removal)5, and a controller10serving as a control unit.

The venous catheter (blood removal) catheter5is inserted from the femoral vein, and passes through the inferior vena cava to have the distal end placed in the right atrium. The venous catheter5is connected to the centrifugal pump3via a blood removal tube (blood removal line)11. The blood removal tube11is a conduit for sending blood.

An arterial catheter (blood transmission catheter)6is inserted from the femoral artery.

The drive motor4actuates the centrifugal pump3based on a command SG from the controller10. The centrifugal pump3sends the blood removed through the blood removal tube11into the artificial lung2, and then returns the resultant blood to a patient P through a blood transmission tube (blood transmission line)12.

The artificial lung2is arranged between the centrifugal pump3and the blood transmission tube12. The artificial lung2performs gas exchange for blood (addition of oxygen and/or removal of carbon dioxide). As the artificial lung2, for example, a membrane type artificial lung can be used, and particularly preferably, a hollow fiber membrane type artificial lung can be used. Oxygen gas is supplied to the artificial lung2from an oxygen gas supply unit13through a tube14. The blood transmission tube12is a conduit connecting the artificial lung2and the arterial catheter6to each other.

As the blood removal tube11and the blood transmission tube12, for example, a conduit made of highly transparent, elastically deformable, and flexible synthetic resin, such as a vinyl chloride resin or silicone rubber, can be used. In the blood removal tube11, the blood, which is liquid, flows in a V1direction, and in the blood transmission tube12, the blood flows in a V2direction.

In the circulation circuit illustrated inFIG. 1, a detection sensor20is arranged at an intermediate portion of the blood removal tube11. A fastening clamp17is arranged at an intermediate portion of the blood transmission tube12.

When bubbles are mixed in the circuit during extracorporeal circulation due to an erroneous operation of a three-way stopcock18, the tube being damaged, or the like, the detection sensor20detects the mixed bubbles by means of ultrasonic waves. When detecting bubbles in the blood sent into the blood removal tube11, the detection sensor20sends a detection signal to the controller10. Based on this detection signal, the controller10issues an alert using an alarm, and reduces the rotation speed of the centrifugal pump3or stops the centrifugal pump3. Further, the controller10commands the fastening clamp17to immediately close the blood transmission tube12. This prevents bubbles from being sent into the body of the patient P. In this manner, the controller10controls the operation of the extracorporeal circulatory device1to prevent bubbles from entering the body of the patient P.

A pressure sensor is provided in the tube11(12,19) of the circulation circuit of the extracorporeal circulatory device1. The pressure sensor can be, for example, provided at at least one of an attachment position A1of the blood removal tube11, an attachment position A2of the blood transmission tube12of the circulation circuit, and an attachment position A3of a connection tube19connecting the centrifugal pump3and the artificial lung2to each other. The pressure sensor measures the pressure inside of each of the tubes11,12, and19while the extracorporeal circulatory device1is performing extracorporeal circulation for the patient P. The mounting position of the pressure sensor is not limited to the attachment positions A1, A2, and A3, and may be attached at any position in the circulation circuit.

First Embodiment

Next, a catheter assembly100according to the present embodiment will be described.FIGS. 2 to 7are diagrams used for a description on the catheter assembly100according to a first embodiment. The catheter assembly100according to the present embodiment includes a catheter30and a stylet50. The catheter30is used as the venous catheter (blood removal catheter)5inFIG. 1.

As illustrated inFIG. 2, the catheter30according to the present embodiment includes a catheter tube31(corresponding to a “tube”) having a side hole63and a distal end tip41that is arranged at the distal end of the catheter tube31and includes through holes46and47. The catheter30includes a clamp tube34arranged on the proximal end side of the catheter tube31, a catheter connector35connecting the catheter tube31and the clamp tube34to each other, and a straight connector36(corresponding to a “connector”) mounted to a proximal end of clamp tube34.

In the present specification, the side to be inserted into the living body is referred to as a “distal end” or “distal end side”, and the side of the hand of the operator performing an operation is referred to as a “proximal end” or “proximal end side”. A distal end portion refers to a certain range including the distal end (distal most end) and the periphery thereof. A proximal end portion refers to a certain range including the proximal end (proximal most end) and the periphery thereof.

The catheter30has a lumen30A formed therethrough from the distal end to the proximal end as illustrated inFIG. 3. The through holes46and47of the distal end tip41and the side hole63of the catheter tube31are arranged in different blood removal targets in the living body so that blood can be efficiently removed.

As illustrated inFIG. 4, the stylet50is used for inserting the catheter30into the living body. The stylet50is inserted into the lumen30A of the catheter30, and the catheter30and the stylet50in a pre-integrated state are inserted into the living body. The lumen30A is configured to enable blood to flow therethrough. How the catheter30is used will be described later.

The catheter tube31is configured to have an elongated shape, and to be expandable and contractible. The catheter tube31includes a first tube32and a second tube33located on the proximal end side of the first tube32as illustrated inFIG. 2. The first tube32is configured to have higher elasticity than the second tube33.

The first tube32is configured to have an outer diameter and an inner diameter that are larger than those of the second tube33. The first tube32and the second tube33are integrally formed, and are configured to have a substantially uniform thickness in a natural, relaxed state.

The first tube32and the second tube33are configured to have lengths required for the through holes46and47of the distal end tip41and the side hole63to be arranged at the desired blood removal targets. The length of the first tube32can be, for example, 20 to 40 cm, and the length of the second tube33can be, for example, 20 to 30 cm.

The side hole63is a hole that is formed through the side surface of the second tube33and is opened to be in communication with the lumen30A of the catheter30. The side hole63functions as a hole for blood removal. The side hole63preferably includes a plurality of holes. With such a configuration, even when any of the holes is closed by being adsorbed on the blood vessel wall, the blood removal can be implemented through the other holes, so that the extracorporeal circulation can be stably implemented.

In the present embodiment, the blood removal targets are two portions that are the right atrium and the inferior vena cava. The catheter30is inserted and placed in the living body to make the through holes46and47of the distal end tip41arranged in the right atrium.

In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is placed in the inferior vena cava which is a relatively thick blood vessel, and the second tube33is placed in the femoral vein which is a relatively thin blood vessel.

When the stylet50is inserted into the lumen30A of the catheter30, as illustrated inFIG. 4, the highly elastic first tube32expands in the axial direction to have the outer diameter and the inner diameter reduced. Then, the outer diameter and inner diameter of the first tube32become substantially the same as the outer diameter and inner diameter of the second tube33. The catheter30is inserted into the living body in a state where the first tube32is expanded in the axial direction to have the outer diameter reduced, and thus can be inserted in a minimally invasive manner.

When the stylet50is removed from the lumen30A of the catheter30after the catheter30has been placed in the living body, the first tube32is contracted in the axial direction to have the outer diameter and the inner diameter increased as illustrated inFIG. 2. The first tube32is placed in the inferior vena cava which a relatively thick blood vessel, and thus can have a large outer diameter.

Here, the pressure loss occurring while the blood or the like flows through the first tube32may be reduced by increasing the inner diameter of the first tube32. When the pressure loss is reduced, the flow rate of the blood flowing through the circulation circuit increases. In view of this, to achieve a sufficient blood circulation amount, the inner diameter of the first tube32needs to be sufficiently large.

When the thickness is substantially uniform, large inner diameters of the first tube32and the second tube33directly relate to large outer diameters thereof, imposing a large load on the patient when the catheter30is inserted in to the living body. As a result, minimally invasive procedures would be ruined.

In view of the above, the inner diameter of the first tube32can be, for example, 9 to 11 mm, and the inner diameter of the second tube33can be, for example, 4 to 8 mm. The thicknesses of the first tube32and the second tube33can be, for example, 0.3 to 0.5 mm.

As illustrated inFIGS. 2 and 3, the distal end portion and the proximal end portion of the first tube32form tapered portions to have diameters gradually decreasing respectively toward the distal end portion and the proximal end portion from the center of the first tube32in the longitudinal direction. This configuration facilitates continuous transition between the inner diameters of the distal end and the proximal end of the first tube32and the inner diameters of the distal end tip41arranged on the distal end side and of the second tube33arranged on the proximal end side.

Next, a specific configuration of the catheter tube31will be described.

As illustrated inFIG. 5, the catheter tube31has a tubular reinforcing body320obtained by braiding wires W in a mesh pattern in an intersecting manner, as well as a first resin layer331and a second resin layer332provided to cover the reinforcing body320.

The first tube32may include a distal end portion320aof the reinforcing body320and the first resin layer331, and the second tube33may include a proximal end portion320bof the reinforcing body320and the second resin layer332.

By braiding the plurality of the wires W, a large number of gap portions or opening portions are formed in the reinforcing body320. The relationship among the plurality of gap portions in size is not particularly limited.

The second resin layer332is formed to cover the inner circumference surface of the opening portion of the reinforcing body320. Thus, the wires can be prevented from being exposed from the inner circumference surface of the side hole63. The maximum length of the opening portion can be about 2 to 3 mm.

The wires W forming the reinforcing body320are made of a shape memory material such as a known shape memory metal or shape memory resin. As the shape memory metal, for example, a titanium-based (such as Ti—Ti, Ti—Pd, or Ti—Nb—Sn) alloy or a copper-based alloy can be used. As the shape memory resin, for example, acrylic resin, a transisoprene polymer, polynorbornene, a styrene-butadiene copolymer, or polyurethane can be used.

In the present embodiment, the wires W forming the reinforcing body320have a rectangular cross-sectional shape. However, this should not be construed in a limiting sense, and a shape other than the above such as square, circular, and elliptical may be employed. When the cross-sectional shape is circular, the diameter of the wire W can be, for example, 0.1 mm to 0.2 mm.

The first resin layer331forming the first tube32is made of a material softer than that of the second resin layer332forming the second tube33. With this configuration, the first tube32can be softer than the second tube33, enabling higher elasticity.

As the material forming the first resin layer331, relatively soft known resin can be used, and for example, a urethane, polyurethane, silicon, or vinyl chloride material having a low hardness can be used. As the material forming the second resin layer332, for example, a urethane, polyurethane, silicon, vinyl chloride material having high hardness can be used.

When urethane or polyurethane is used, the surface may be provided with hydrophilic coating. With this configuration, the catheter tube31can have high surface lubricity and can be easily inserted into the living body, whereby operability is improved, and the blood vessel wall can be prevented from being damaged. Furthermore, attachment of blood and proteins is less likely to occur, and thus formation of a blood clot can also be expected to be prevented.

The distal end tip41is fixed to the distal end of the first tube32. As illustrated inFIG. 6, the distal end tip41has a tapered shape with the diameter gradually decreasing toward the distal end side. As illustrated inFIG. 6, the distal end tip41includes a base portion49inserted into the distal end of the first tube32, the plurality of through holes46provided on the side surface, and the through hole47provided at the distal end of the distal end tip41. The through holes46and47function as holes for blood removal. The through hole47of the distal end tip41is configured to communicate with the lumen30A of the catheter30. The distal end tip41can be formed of, for example, hard plastic or the like.

Further, with the hard distal end tip41fixed to the distal end portion of the first tube32, the first tube32can be prevented from being crushed during blood removal.

As illustrated inFIG. 5, a flat receiving surface48(corresponding to “first contact portion”) that comes into contact with a flat surface50aof the stylet50used before the insertion of the catheter30into the living body is formed on the inner side of the distal end tip41. As will be described later, with the distal end of the stylet50being in contact with the receiving surface48, the catheter30expands in the longitudinal direction.

The clamp tube34is provided on the proximal end side of the second tube33. A lumen into which the stylet50can be inserted can be provided on the inner side of the clamp tube34. The clamp tube34can be formed using the same material as the catheter tube31.

The catheter connector35connects the second tube33and the clamp tube34to each other. A lumen into which the stylet50can be inserted can be provided on the inner side of the catheter connector35.

The straight connector36is provided on the proximal end side of the catheter30. The straight connector36is sturdily affixed to the proximal end side of the clamp tube34(e.g., clamp tube34grips a distal end of straight connector36so that no sliding or rotation occurs between them). The straight connector36has a circular shape in a cross section intersecting the longitudinal direction in the proximal end portion. A lumen into which the stylet50can be inserted can be provided on the inner side of the straight connector36. The straight connector36has an outer circumference provided with a male screw portion36A (corresponding to “first engagement portion”) that can engage with a female screw portion53C of the stylet50. The straight connector36is configured to be capable of being coupled to the stylet50by means of the male screw portion36A.

The stylet50includes a stylet tube51extending in the axial direction, and a stylet hub52(corresponding to a “hub”) to which the proximal end of the stylet tube51is fixed as illustrated inFIG. 2. The stylet50includes a coupling member53provided on the distal end side of the stylet hub52and coupling the stylet hub52and the straight connector36to each other.

The stylet tube51is a relatively rigid elongated body that extends in the axial direction. The stylet tube51is configured to be capable of being inserted into the lumen30A of the catheter30. The total length of the stylet tube51along the axial direction is configured to be longer than the total length (in its natural, relaxed state) of the catheter30along the axial direction. The stylet tube51includes a guide wire lumen54through which a guide wire (not illustrated) can be inserted (seeFIG. 5). The stylet tube51is inserted into the living body together with the catheter30while being guided by the guide wire. The stylet tube51is removed from the catheter30by pulling out the stylet hub52toward the proximal end side, after the catheter30has been placed in the living body.

The distal end of the stylet tube51includes the flat surface50athat comes into contact with the receiving surface48of the distal end tip41as illustrated inFIG. 5. The stylet tube51has a relatively high rigidity, and has a stiffness to enable pushing force toward the distal end side, applied by an operation with the hand, to be transmitted to the distal end tip41. Thus, the stylet tube51has a function of expanding the catheter tube31in the longitudinal direction and dilating a narrow blood vessel, by bringing the flat surface50aof the stylet tube51to contact with the receiving surface48of the distal end tip41and pushing the distal end tip41toward the distal end side.

The stylet hub52is arranged on the proximal end side of the catheter30when the catheter30is coupled to the stylet50. As illustrated inFIG. 7, the stylet hub52includes an extending portion52A extending along a first enclosing portion53B of the coupling member53described later, on the outer side of the stylet hub52in the circumferential direction. The extending portion52A is formed to have a hollow circular shape in a cross section intersecting the longitudinal direction which receives a proximal end of straight connector36. For clarity, clamp tube34which would be connected to the distal end of straight connector36is not shown inFIG. 7.

As illustrated inFIG. 7, the coupling member53includes the first enclosing portion53B that extends in the longitudinal direction so as to enclose a space between an attachment portion53A attached to the stylet hub52and the female screw portion53C (second engagement portion) described later. The attachment portion53A is rotatably attached to the stylet hub52. The attachment portion53A is arranged to be separated from a notched outer surface52D of the stylet hub52in a radial direction. The attachment portion53A fits into notched surface52D and applies pressing force on an outer surface52E of the stylet hub52, and applies force to fix the stylet hub52to the straight connector36in the longitudinal direction in response to screwing between the male screw portion36A and the female screw portion53C described later. The extending portion52A extends along the first enclosing portion53B and comes into contact with the male screw portion36A (engagement portion). When the male screw portion36A and the extending portion52A come into surface contact with each other, a sealing portion55sealing the proximal end side of the catheter30is formed between the catheter30and the stylet50.

The coupling member53includes the female screw portion53C that is provided on the distal end side of the first enclosing portion53B and engages with the male screw portion36A by screwing, and can engage with the male screw portion36A by rotating independently of the stylet hub52. The female screw portion53C is provided on the side opposite to the attachment portion53A in the longitudinal direction. The female screw portion53C enables the coupling member53to be detachably attached to the straight connector36through screwing. The female screw portion53C corresponds to the second engagement portion in the present specification.

Next, how the catheter assembly100described above is used will be described.FIG. 2illustrates a state before the stylet tube51of the stylet50is inserted into the lumen30A of the catheter30, andFIG. 4illustrates a state after the stylet tube51has been inserted into the lumen30A of the catheter30.

An operator such as a physician first inserts the stylet tube51of the stylet50into the lumen30A of the catheter30as illustrated inFIG. 4. As a result, the stylet tube51passes through the inside of the straight connector36, the clamp tube34, the catheter connector35, the second tube33, and the first tube32in this order. Then, the flat surface50aof the stylet tube51comes into contact with the receiving surface48of the distal end tip41(seeFIG. 5).

The total length of the stylet tube51along the axial direction is configured to be longer than the total length of the catheter30along the axial direction as illustrated inFIG. 2. Thus, the distal end tip41is pressed toward the distal end side, with the flat surface50aof the stylet tube51being in contact with the receiving surface48of the distal end tip41. As a result, the distal end of the first tube32fixed to the distal end tip41is pulled toward the distal end side.

Thus, the catheter30receives force in the expanding direction, and the first tube32, which is a relatively elastic portion of the catheter30, expands in the axial direction. When the first tube32expands in the axial direction, the outer diameter of the first tube32decrease to be substantially the same as the outer diameter of the second tube33. With the first tube32expanding in the axial direction, the proximal end of the catheter30and the stylet hub52are fixed to each other. The proximal end of the catheter30and the stylet hub52are fixed to each other, when the female screw portion53C and the male screw portion36A engage with each other due to a manual rotation of the coupling member53.

Next, the operator inserts the catheter30through which the stylet tube51is inserted, along a guide wire (not illustrated) that has been inserted into the target portion in the living body in advance. In this processing, by inserting the stylet50into the catheter30, the outer diameter of the first tube32becomes substantially the same as the outer diameter of the second tube33. Therefore, the catheter30can be inserted into the living body in a minimally invasive manner. The operator inserts the catheter30into the living body until the through holes46and47of the distal end tip41are placed in the right atrium and the side hole63is placed in the inferior vena cava, and holds the catheter30in this state. In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is arranged in the inferior vena cava which is a relative thick blood vessel, and the second tube33is arranged in the femoral vein which is a relatively thin blood vessel.

The operator then removes the stylet tube51and the guide wire from the catheter30by unscrewing coupling member53from straight connector36. In this process, the stylet tube51and the guide wire are first pulled out to a position of the straight connector36of the catheter30, temporarily clamped by forceps (not illustrated), and then is completely removed from the catheter30. When the stylet tube51is removed from the lumen30A of the catheter30, the catheter30is released from force in a direction for causing it to expand in the axial direction, received from the stylet50. Therefore, the first tube32contracts in the axial direction, and the outer diameter and inner diameter of the first tube32increase. Thus, the pressure loss in the first tube32can be reduced.

Next, the operator connects the straight connector36of the catheter30to the blood removal tube11of the extracorporeal circulatory device1illustrated inFIG. 1. Once completion of the connection of the catheter on the blood transmission is confirmed, the forceps of the clamp tube34are released and extracorporeal circulation starts.

When the extracorporeal circulation ends, the operator removes the catheter30from the blood vessel and performs hemostatic repair on the insertion site through a surgical procedure if necessary.

As described above, the catheter assembly100according to the present embodiment includes a catheter30and a stylet50. The catheter30includes the catheter tube31, the receiving surface48, and the straight connector36. The catheter tube31is formed to have an elongated shape, is provided with the lumen30A in which the blood can flow, and is configured to be expandable and contractible. The receiving surface48is provided in the distal end portion of the catheter tube31, and enables the catheter tube31to expand in the longitudinal direction by the contacting. The straight connector36is provided on the proximal end side of the catheter30and is configured to be capable of being coupled with the stylet50. The straight connector36includes the male screw portion36A that can be engaged with the stylet50. The stylet50is configured to be capable of being inserted into the lumen30A, allows the catheter tube31to expand in the longitudinal direction by coming into contact with the receiving surface48, and includes the stylet hub52and the coupling member53. The stylet hub52is arranged on the proximal end side of the catheter30. The coupling member53couples the stylet hub52and the straight connector36to each other, and is configured to be engageable with the male screw portion36A by rotating independently of the stylet hub52.

With this configuration, even when the coupling member53rotates, no or almost no rotation of the coupling member53is transmitted to the stylet hub52. Thus, twisting occurring at the distal end of the catheter30can be prevented or suppressed when the stylet50is connected to the catheter30. Thus, deterioration of the insertability of the catheter30for percutaneous insertion can be prevented or suppressed.

Furthermore, the coupling member53includes the attachment portion53A that is rotatably attached to the stylet hub52. The attachment portion53A is arranged to be separated from an outer surface52D of the stylet hub52in a radial direction or a radiation direction. This enables the coupling member53to be less likely to be in contact with the stylet hub52at the attachment portion53A. Thus, when the coupling member53is rotated relatively with respect to the stylet hub52, the twisting due to the stylet hub52rotating together with the coupling member53can be prevented or suppressed.

Further, the coupling member53includes the female screw portion53C that is provided on the opposite side of the attachment portion53A in the longitudinal direction and is engageable with the male screw portion36A through screwing. The attachment portion53A is configured to apply force to fix the stylet hub52to the straight connector36in the longitudinal direction, in response to screwing between the male screw portion36A and the female screw portion53C. With the stylet hub52and the coupling member53thus configured to be integrated, and provide tightening force in the longitudinal direction and not in the radial direction or the radiation direction, contact therebetween the in radial direction or the radiation direction is not required. Thus, the attachment portion53A can be arranged to be separated from the stylet hub52in the radial direction or the radiation direction as described above, meaning that the contact surface as a result of rotation of one of these can be relatively small. All things considered, twisting due to the rotation of the coupling member53can be prevented or suppressed.

First Modification

Next, a catheter assembly100A according to a first modification will be described with reference toFIG. 8.FIGS. 8 to 12are diagrams used for a description on a main part of the catheter assembly100A according to the first modification.

As illustrated inFIG. 8, the catheter assembly100A according to the first modification is different from the first embodiment in that it includes a straight connector36B forming a portion of a catheter30B and a stylet hub520forming a portion of a stylet50A. The other configurations are substantially the same as those in the first embodiment, and the description to be redundant herein is basically omitted.

The straight connector36B has a proximal end portion36C that is formed more linearly than the proximal end portion of the straight connector36. The straight connector36B has a circular shape in a cross section intersecting the longitudinal direction in the proximal end portion36C, as in the case of the straight connector36of the first embodiment.

The stylet hub520includes a second enclosing portion520A capable of surrounding the proximal end portion36C of the straight connector36B, on the outer circumference of the straight connector36B. The second enclosing portion520A is configured to be capable of coming into contact with the outer side surface of the proximal end portion36C of the straight connector36B. The second enclosing portion520A is configured to have a length, in the longitudinal direction, shorter than that of the extending portion52A of the stylet hub52. Further, the second enclosing portion520A is configured to be separated from the first enclosing portion53B of the coupling member53in the radial direction or the radiation direction. The second enclosing portion520A corresponds to a second contact portion in the present specification.

The second enclosing portion520A and the outer side surface of the proximal end portion36C of the straight connector36B may be in surface contact with each other while being inclined in substantially the same manner with respect to the longitudinal direction as illustrated inFIG. 9andFIG. 10, and thus a sealing portion550sealing the proximal end side of the catheter30may be formed.

This configuration should not be construed in a limiting sense. For example, a second enclosing portion520C of the stylet hub520B and the outer side surface of the proximal end portion36C of the straight connector36B may be different from each other in the inclination with respect to the longitudinal direction as illustrated inFIG. 11andFIG. 12. In this case, at least one of the two is deformed at a portion with different inclinations so that they are in circumferential surface contact with each other around the longitudinal direction. Thus, a sealing portion550A is formed at the portion of the surface contact. An outer surface520D of the stylet hubs520and520B illustrated inFIGS. 9 and 11corresponds to the outer surface52D, an outer surface520E corresponds to the outer surface52E, and the second enclosing portion520C corresponds to the second contact portion.

As described above, in the first modification, the coupling member53is configured to rotate independently of the stylet hub520,520B as in the first embodiment. Thus, as in the first embodiment, twisting occurring at the distal end of the catheter30B can be prevented or suppressed when the stylet50A is connected to the catheter30B, and deterioration of the insertability of the catheter30B for percutaneous insertion can be prevented or suppressed.

Further, the stylet hub520,520B includes the second enclosing portion520A,520C that comes into contact with the straight connector36B on the proximal end side of the catheter30B. The second enclosing portions520A and520C are arranged to be separated from the first enclosing portion53B in the radial direction or the radiation direction. With this configuration, the contact area between the coupling member53and the stylet hubs520and520B can be relatively small. Thus, when the coupling member53is rotated relatively with respect to the stylet hub520,520B, the twisting due to the stylet hub520,520B rotating together with the coupling member53can be prevented or suppressed.

When the sealing portion550is formed with the second enclosing portion520A being in contact with the outer side surface of the proximal end portion36C of the straight connector36B as in the present first modification, no contact occurs on the inner circumference surface of the straight connector36B. Thus, when surface treatment such as polymer coating is provided on the inner circumference surface, such coating or the like can be prevented from peeling. The same applies to the sealing portion55in the first embodiment.

Second Modification

Next, a catheter assembly100B according to a second modification will be described with reference toFIG. 13.FIG. 13is a diagram used for a description on a main part of the catheter assembly100B according to the second modification.

The catheter assembly100B according to the second modification is, like the first modification, different from the first embodiment in that it includes a straight connector36D forming a catheter30C and a stylet hub521forming a stylet50B. Further, the straight connector36D of the second modification has a proximal end portion provided with a tapered surface36E formed in a tapered shape. The other configurations are substantially the same as in the first embodiment.

The stylet hub521includes a contact portion521A capable of contacting the tapered surface36E, and a sealing portion551sealing the proximal end side of the catheter30is configured by surface contact between the tapered surface36E and the contact portion521A. Further, the contact portion521A is arranged to be separated from the first enclosing portion53B of the coupling member53in the radial direction or the radiation direction as in the first modification. The contact portion521A corresponds to the second contact portion in the present specification, an outer surface521D corresponds to the outer surface52D in the first embodiment, and an outer surface521E corresponds to the outer surface52E.

As described above, in the second modification, the coupling member53is configured to rotate independently of the stylet hub521as in the first embodiment. Thus, as in the first embodiment, twisting occurring at the distal end of the catheter30C can be prevented or suppressed when the stylet50B is connected to the catheter30C, and deterioration of the insertability of the catheter30C for percutaneous insertion can be prevented or suppressed.

Further, the stylet hub521includes the contact portion521A that comes into contact with the straight connector36D on the proximal end side of the catheter30C. The contact portion521A is arranged to be separated from the first enclosing portion53B in the radial direction or the radiation direction. Thus, as in the first modification, when the coupling member53is rotated relatively with respect to the stylet hub521, the twisting due to the stylet hub521rotating together with the coupling member53can be prevented or suppressed. Further, since the coupling member53rotates independently of the stylet hub521, friction between the proximal end side of the catheter30C and the contact portion521A of the stylet hub521can be prevented. Thus, a coating agent can be prevented from peeling.

Second Embodiment

Next, a catheter assembly200according to a second embodiment of the present invention will be described with reference toFIGS. 14 to 16.FIGS. 14 to 16are diagrams used for a description on the configuration of the catheter assembly200according to the second embodiment. The catheter assembly200according to the present embodiment has a percutaneous catheter (hereinafter referred to as “catheter”)60different from that in the first embodiment.

This catheter60is what is known as a double lumen catheter configured to simultaneously enable both transmission and removal of blood. Thus, in the present embodiment, the catheter60is in charge of functions of two catheters, that is, the venous catheter (blood removal catheter)5and the arterial catheter (blood transmission catheter)6in the extracorporeal circulatory device1inFIG. 1.

The catheter60according to the present embodiment is different from the catheter30according to the first embodiment in that a double tube structure is provided as illustrated inFIGS. 15 and 16. In such a structure, a third tube161having a first lumen61in communication with a blood transmission side hole163is provided inside a lumen of the second tube33.

With the catheter60, the blood is removed from a vein (vena cava) of the patient with a pump of the extracorporeal circulatory device1activated. Thereafter, gas exchange inside the blood is performed with the artificial lung2to oxygenate the blood, and then the resultant blood is returned to the vein (vena cava) of the patient again. In this manner, the Veno-Venous (VV) procedure can be performed.

Hereinafter, each configuration of the catheter60will be described. The parts common to the first embodiment will be omitted, and characteristic parts of the present embodiment will be described. The parts having the same functions as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As illustrated inFIG. 15, the catheter60includes the first tube32, the second tube33, the distal end tip41that is provided at the distal end of the first tube32and includes the through holes46and47, and the third tube161provided inside the second tube33.

As illustrated inFIG. 15, the catheter60includes the first lumen61that functions as the blood transmission channel and a second lumen62that functions as the blood removal channel.

The first lumen61is formed inside the third tube161. The second lumen62is formed through the first tube32and the second tube33, from the distal end to the proximal end.

The second tube33includes the blood transmission side hole163in communication with the first lumen61that is the blood transmission channel and a blood removal side hole164in communication with the second lumen62that is the blood removal channel. The blood transmission side hole163and the blood removal side hole164are formed to have an elliptical shape, but are not limited this shape.

The third tube161is configured to be inserted into the second lumen62from the proximal end side of the second tube33and to be in communication with the blood transmission side hole163.

The blood transmission side hole163is arranged in the blood transmission target in the living body. The blood oxygenated by the artificial lung2is transmitted into the living body through the blood transmission side hole163.

The through holes46and47of the distal end tip41and blood removal side hole164are arranged in different blood removal targets in the living body so that blood can be efficiently removed. When the through hole46,47or the blood removal side hole164is closed as a result of being adsorbed on a blood vessel wall, blood can be removed through unclosed one of the holes, whereby extracorporeal circulation can be stably performed.

In the present embodiment, the catheter60is inserted from the internal jugular vein of the neck, passes through the superior vena cava and the right atrium, to have the distal end placed in the inferior vena cava. The blood transmission target is the right atrium, and the blood removal target includes two portions that are the superior vena cava and the inferior vena cava.

As illustrated inFIGS. 14 and 15, the catheter60is inserted, in a state where the stylet50is inserted, into the living body and is held once the through holes46and47of the distal end tip41are placed in the inferior vena cava and the blood removal side hole164is placed in the internal jugular vein.

As in the first embodiment, the first tube32is configured to have an inner diameter that is larger than that of the second tube33. In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is placed in the inferior vena cava which is a relatively thick blood vessel, and the second tube33is placed in the femoral vein which is a relatively thin blood vessel.

As illustrated inFIG. 15, a straight connector136includes a first straight connector137and a second straight connector138. The first straight connector137is configured to communicate with the first lumen61, and the second straight connector138is configured to communicate with the second lumen62. The straight connector136is configured as a Y-shaped Y connector formed with the first straight connector137branched from the second straight connector138. For the sake of illustration, inFIG. 15, the first straight connector137and the second straight connector138are close to each other, but the first straight connector137and the second straight connector138are actually arranged to be more separated from each other by an amount larger than that illustrated inFIG. 15.

The first straight connector137is coupled to the proximal end portion of the third tube161. The second straight connector138is coaxially coupled to the proximal end portion of the second tube33. A blood transmission tube (blood transmission line) is connected to the first straight connector137, and a blood removal tube (blood removal line) is connected to the second straight connector138. The first straight connector137is provided with a male screw portion137A, and the second straight connector138is provided with a male screw portion138A.

The first tube32is configured to function in the same manner as in the first embodiment. When the stylet50is inserted into the catheter60, as illustrated inFIG. 16, the first tube32expands to have the outer diameter and the inner diameter reduced. As a result, the catheter60can be inserted into the living body in a minimally invasive manner. When the stylet50is removed from the catheter60, the first tube32is contracted in the axial direction to have the inner diameter increased as illustrated inFIG. 14. Thus, the pressure loss inside the first tube32can be reduced.

As described above, the catheter assembly200of the present embodiment has the catheter60. Thus, both blood removal and blood transmission functions can be provided with a single catheter. As in the first embodiment, twisting occurring at the distal end of the catheter60can be prevented or suppressed when the stylet50is connected to the catheter60, and deterioration of the insertability of the catheter60for percutaneous insertion can be prevented or suppressed.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. The embodiments and the like in which the catheter30includes the straight connector36have been described above. However, the type of the connector is not limited to the straight connector as long as a sealing portion can be formed and the connector can be connected to a mating component.

In a circulation circuit as described in U.S. Pat. No. 7,748,275B2 as a conventional technique, a catheter including a blood transmission hole (outflow hole) for transmitting blood after gas exchange to a desired position of a living body is used. The catheter is moved to the desired lumen of the living body and then connected to another component forming the circulation circuit.

Before the catheter is connected to the other component, the stylet is inserted in the catheter. If the sealing between the catheter and the stylet might is insufficient, the blood might leak. Thus, the sealing therebetween needs to be reliably obtained.

Therefore, in the embodiments described below, a catheter assembly with which the sealing between the catheter and the stylet can be reliably obtained will be described.

A catheter assembly achieving the above object includes: a catheter including a tube that is formed to have an elongated shape, is provided with a lumen in which blood is flowable, and is expandable and contractible, and a contact portion contacting by which enables the tube to expand in a longitudinal direction, the contact portion being provided in a distal end portion of the tube; a stylet that is configured to be capable of being inserted in the lumen, and enables the tube to expand in the longitudinal direction by coming into contact with the contact portion; a connector capable of coupling with the stylet, the connector being provided on a proximal end side of the catheter; and a sealing portion that is provided between the catheter and the stylet and seals the proximal end side of the catheter The connector includes an engagement portion engageable with the stylet, and the stylet includes a hub disposed on the proximal end side of the catheter and a coupling member that couples the hub and the connector to each other and is engageable with the engagement portion.

With the catheter assembly configured as described above, a sealing portion sealing the proximal end side of the catheter is provided between the catheter and the stylet, and thus the sealing therebetween can be reliably obtained.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.FIG. 1is a diagram illustrating an example of an extracorporeal circulatory device employing a catheter provided in a catheter assembly according to an embodiment of the present invention. The extracorporeal circulatory device can be used, for example, in percutaneous cardiopulmonary support (PCPS), which temporarily assists or substitutes for heart and lung functions until the cardiac function of a patient with a weakened heart is restored.

An extracorporeal circulatory device1can be used for veno-arterial (VA) procedures. In the venous-arterial procedure (VA), a pump is actuated to remove blood from a patient's vein (for example, a large vein), an artificial lung2exchanges gas in the blood to oxygenate the blood, and the resultant blood is returned to an artery (for example, aorta). As described above, the extracorporeal circulatory device1can be used as a device for assisting the heart and lungs of the patient. Hereinafter, the procedure of removing blood from a patient, performing a predetermined treatment on the blood outside the body, and then transmitting the blood back into the patient's body is referred to as “extracorporeal circulation”.

As illustrated inFIG. 1, the extracorporeal circulatory device1includes a circulation circuit for circulating blood. The circulation circuit includes the artificial lung2, a centrifugal pump3, a drive motor4serving as a driving unit for driving the centrifugal pump3, a venous catheter (percutaneous catheter for blood removal)5, and a controller10serving as a control unit.

The venous catheter (blood removal) catheter5is inserted from the femoral vein, and passes through the inferior vena cava to have the distal end placed in the right atrium. The venous catheter5is connected to the centrifugal pump3via a blood removal tube (blood removal line)11. The blood removal tube11is a conduit for sending blood.

An arterial catheter (blood transmission catheter)6is inserted from the femoral artery.

The drive motor4actuates the centrifugal pump3based on a command SG from the controller10. The centrifugal pump3sends the blood removed through the blood removal tube11into the artificial lung2, and then returns the resultant blood to a patient P through a blood transmission tube (blood transmission line)12.

The artificial lung2is arranged between the centrifugal pump3and the blood transmission tube12. The artificial lung2performs gas exchange for blood (addition of oxygen and/or removal of carbon dioxide). As the artificial lung2, for example, a membrane type artificial lung can be used, and particularly preferably, a hollow fiber membrane type artificial lung can be used. Oxygen gas is supplied to the artificial lung2from an oxygen gas supply unit13through a tube14. The blood transmission tube12is a conduit connecting the artificial lung2and the arterial catheter6to each other.

As the blood removal tube11and the blood transmission tube12, for example, a conduit made of highly transparent, elastically deformable, and flexible synthetic resin, such as a vinyl chloride resin or silicone rubber, can be used. In the blood removal tube11, the blood, which is liquid, flows in a V1direction, and in the blood transmission tube12, the blood flows in a V2direction.

In the circulation circuit illustrated inFIG. 1, a detection sensor20is arranged at an intermediate portion of the blood removal tube11. A fastening clamp17is arranged at an intermediate portion of the blood transmission tube12.

When bubbles are mixed in the circuit during extracorporeal circulation due to an erroneous operation of a three-way stopcock18, the tube being damaged, or the like, the detection sensor20detects the mixed bubbles by means of ultrasonic waves. When detecting bubbles in the blood sent into the blood removal tube11, the detection sensor20sends a detection signal to the controller10. Based on this detection signal, the controller10issues an alert using an alarm, and reduces the rotation speed of the centrifugal pump3or stops the centrifugal pump3. Further, the controller10commands the fastening clamp17to immediately close the blood transmission tube12. This prevents bubbles from being sent into the body of the patient P. In this manner, the controller10controls the operation of the extracorporeal circulatory device1to prevent bubbles from entering the body of the patient P.

A pressure sensor is provided in the tube11(12,19) of the circulation circuit of the extracorporeal circulatory device1. The pressure sensor can be, for example, provided at at least one of an attachment position A1of the blood removal tube11, an attachment position A2of the blood transmission tube12of the circulation circuit, and an attachment position A3of a connection tube19connecting the centrifugal pump3and the artificial lung2to each other. The pressure sensor measures the pressure inside of each of the tubes11,12, and19while the extracorporeal circulatory device1is performing extracorporeal circulation for the patient P. The mounting position of the pressure sensor is not limited to the attachment positions A1, A2, and A3, and may be attached at any position in the circulation circuit.

Third Embodiment

Next, a catheter assembly100according to the present embodiment will be described.FIGS. 2 to 7are diagrams used for a description on the catheter assembly100according to a third embodiment. The catheter assembly100according to the present embodiment includes a catheter30and a stylet50. The catheter30is used as the venous catheter (blood removal catheter)5inFIG. 1.

As illustrated inFIG. 2, the catheter30according to the present embodiment includes a catheter tube31(corresponding to a “tube”) having a side hole63and a distal end tip41that is arranged at the distal end of the catheter tube31and includes through holes46and47. The catheter30includes a clamp tube34arranged on the proximal end side of the catheter tube31, a catheter connector35connecting the catheter tube31and the clamp tube34to each other, and a straight connector36(corresponding to a “connector”) mounted to a proximal end of clamp tube34.

In the present specification, the side to be inserted into the living body is referred to as a “distal end” or “distal end side”, and the side of the hand of the operator performing an operation is referred to as a “proximal end” or “proximal end side”. A distal end portion refers to a certain range including the distal end (distal most end) and the periphery thereof. A proximal end portion refers to a certain range including the proximal end (proximal most end) and the periphery thereof.

The catheter30has a lumen30A formed therethrough from the distal end to the proximal end as illustrated inFIG. 3. The through holes46and47of the distal end tip41and the side hole63of the catheter tube31are arranged in different blood removal targets in the living body so that blood can be efficiently removed.

As illustrated inFIG. 4, the stylet50is used for inserting the catheter30into the living body. The stylet50is inserted into the lumen30A of the catheter30, and the catheter30and the stylet50in a pre-integrated state are inserted into the living body. The lumen30A is configured to enable blood to flow therethrough. How the catheter30is used will be described later.

The catheter tube31is configured to have an elongated shape, and to be expandable and contractible. The catheter tube31includes a first tube32and a second tube33located on the proximal end side of the first tube32as illustrated inFIG. 2. The first tube32is configured to have higher elasticity than the second tube33.

The first tube32is configured to have an outer diameter and an inner diameter that are larger than those of the second tube33. The first tube32and the second tube33are integrally formed, and are configured to have a substantially uniform thickness in a natural, relaxed state.

The first tube32and the second tube33are configured to have lengths required for the through holes46and47of the distal end tip41and the side hole63to be arranged at the desired blood removal targets. The length of the first tube32can be, for example, 20 to 40 cm, and the length of the second tube33can be, for example, 20 to 30 cm.

The side hole63is a hole that is formed through the side surface of the second tube33and is opened to be in communication with the lumen30A of the catheter30. The side hole63functions as a hole for blood removal. The side hole63preferably includes a plurality of holes. With such a configuration, even when any of the holes is closed by being adsorbed on the blood vessel wall, the blood removal can be implemented through the other holes, so that the extracorporeal circulation can be stably implemented.

In the present embodiment, the blood removal targets are two portions that are the right atrium and the inferior vena cava. The catheter30is inserted and placed in the living body to make the through holes46and47of the distal end tip41arranged in the right atrium.

In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is placed in the inferior vena cava which is a relatively thick blood vessel, and the second tube33is placed in the femoral vein which is a relatively thin blood vessel.

When the stylet50is inserted into the lumen30A of the catheter30, as illustrated inFIG. 4, the highly elastic first tube32expands in the axial direction to have the outer diameter and the inner diameter reduced. Then, the outer diameter and inner diameter of the first tube32become substantially the same as the outer diameter and inner diameter of the second tube33. The catheter30is inserted into the living body in a state where the first tube32is expanded in the axial direction to have the outer diameter reduced, and thus can be inserted in a minimally invasive manner.

When the stylet50is removed from the lumen30A of the catheter30after the catheter30has been placed in the living body, the first tube32is contracted in the axial direction to have the outer diameter and the inner diameter increased as illustrated inFIG. 2. The first tube32is placed in the inferior vena cava which a relatively thick blood vessel, and thus can have a large outer diameter.

Here, the pressure loss occurring while the blood or the like flows through the first tube32may be reduced by increasing the inner diameter of the first tube32. When the pressure loss is reduced, the flow rate of the blood flowing through the circulation circuit increases. In view of this, to achieve a sufficient blood circulation amount, the inner diameter of the first tube32needs to be sufficiently large.

When the thickness is substantially uniform, large inner diameters of the first tube32and the second tube33directly relate to large outer diameters thereof, imposing a large load on the patient when the catheter30is inserted in to the living body. As a result, minimally invasive procedures would be ruined.

In view of the above, the inner diameter of the first tube32can be, for example, 9 to 11 mm, and the inner diameter of the second tube33can be, for example, 4 to 8 mm. The thicknesses of the first tube32and the second tube33can be, for example, 0.3 to 0.5 mm.

As illustrated inFIGS. 2 and 3, the distal end portion and the proximal end portion of the first tube32form tapered portions to have diameters gradually decreasing respectively toward the distal end portion and the proximal end portion from the center of the first tube32in the longitudinal direction. This configuration facilitates continuous transition between the inner diameters of the distal end and the proximal end of the first tube32and the inner diameters of the distal end tip41arranged on the distal end side and of the second tube33arranged on the proximal end side.

Next, a specific configuration of the catheter tube31will be described.

As illustrated inFIG. 5, the catheter tube31has a tubular reinforcing body320obtained by braiding wires W in a mesh pattern in an intersecting manner, as well as a first resin layer331and a second resin layer332provided to cover the reinforcing body320.

The first tube32may include a distal end portion320aof the reinforcing body320and the first resin layer331, and the second tube33may include a proximal end portion320bof the reinforcing body320and the second resin layer332.

By braiding the plurality of the wires W, a large number of gap portions or opening portions are formed in the reinforcing body320. The relationship among the plurality of gap portions in size is not particularly limited.

The second resin layer332is formed to cover the inner circumference surface of the opening portion of the reinforcing body320. Thus, the wires can be prevented from being exposed from the inner circumference surface of the side hole63. The maximum length of the opening portion can be about 2 to 3 mm.

The wires W forming the reinforcing body320are made of a shape memory material such as a known shape memory metal or shape memory resin. As the shape memory metal, for example, a titanium-based (such as Ti—Ti, Ti—Pd, or Ti—Nb—Sn) alloy or a copper-based alloy can be used. As the shape memory resin, for example, acrylic resin, a transisoprene polymer, polynorbornene, a styrene-butadiene copolymer, or polyurethane can be used.

In the present embodiment, the wires W forming the reinforcing body320have a rectangular cross-sectional shape. However, this should not be construed in a limiting sense, and a shape other than the above such as square, circular, and elliptical may be employed. When the cross-sectional shape is circular, the diameter of the wire W can be, for example, 0.1 mm to 0.2 mm.

The first resin layer331forming the first tube32is made of a material softer than that of the second resin layer332forming the second tube33. With this configuration, the first tube32can be softer than the second tube33, enabling higher elasticity.

As the material forming the first resin layer331, relatively soft known resin can be used, and for example, a urethane, polyurethane, silicon, or vinyl chloride material having a low hardness can be used. As the material forming the second resin layer332, for example, a urethane, polyurethane, silicon, vinyl chloride material having high hardness can be used.

When urethane or polyurethane is used, the surface may be provided with hydrophilic coating. With this configuration, the catheter tube31can have high surface lubricity and can be easily inserted into the living body, whereby operability is improved, and the blood vessel wall can be prevented from being damaged. Furthermore, attachment of blood and proteins is less likely to occur, and thus formation of a blood clot can also be expected to be prevented.

The distal end tip41is fixed to the distal end of the first tube32. As illustrated inFIG. 6, the distal end tip41has a tapered shape with the diameter gradually decreasing toward the distal end side. As illustrated inFIG. 6, the distal end tip41includes a base portion49inserted into the distal end of the first tube32, the plurality of through holes46provided on the side surface, and the through hole47provided at the distal end of the distal end tip41. The through holes46and47function as holes for blood removal. The through hole47of the distal end tip41is configured to communicate with the lumen30A of the catheter30. The distal end tip41can be formed of, for example, hard plastic or the like.

Further, with the hard distal end tip41fixed to the distal end portion of the first tube32, the first tube32can be prevented from being crushed during blood removal.

The flat receiving surface48(corresponding to “contact portion”) that comes into contact with the flat surface50aof the stylet50used before the insertion of the catheter30into the living body is formed on the inner side of the distal end tip41, as illustrated inFIG. 5. As will be described later, with the distal end of the stylet50being in contact with the receiving surface48, the catheter30expands in the longitudinal direction.

The clamp tube34is provided on the proximal end side of the second tube33. A lumen into which the stylet50can be inserted can be provided on the inner side of the clamp tube34. The clamp tube34can be formed using the same material as the catheter tube31.

The catheter connector35connects the second tube33and the clamp tube34to each other. A lumen into which the stylet50can be inserted can be provided on the inner side of the catheter connector35.

The straight connector36is provided on the proximal end side of the catheter30. The straight connector36is sturdily affixed to the proximal end side of the clamp tube34(e.g., clamp tube34grips a distal end of straight connector36so that no sliding or rotation occurs between them). The straight connector36has a circular shape in a cross section intersecting the longitudinal direction in the proximal end portion. A lumen into which the stylet50can be inserted can be provided on the inner side of the straight connector36. The straight connector36has an outer circumference provided with a male screw portion36A (corresponding to “engagement portion”) that can engage with a female screw portion53C of the stylet50. The straight connector36is configured to be capable of being coupled to the stylet50by means of the male screw portion36A.

The stylet50includes a stylet tube51extending in the axial direction, and a stylet hub52(corresponding to a “hub”) to which the proximal end of the stylet tube51is fixed as illustrated inFIG. 2. The stylet50includes a coupling member53provided on the distal end side of the stylet hub52and coupling the stylet hub52and the straight connector36to each other.

The stylet tube51is a relatively rigid elongated body that extends in the axial direction. The stylet tube51is configured to be capable of being inserted into the lumen30A of the catheter30. The total length of the stylet tube51along the axial direction is configured to be longer than the total length (in its natural, relaxed state) of the catheter30along the axial direction. The stylet tube51includes a guide wire lumen54through which a guide wire (not illustrated) can be inserted (seeFIG. 5). The stylet tube51is inserted into the living body together with the catheter30while being guided by the guide wire. The stylet tube51is removed from the catheter30by pulling out the stylet hub52toward the proximal end side, after the catheter30has been placed in the living body.

The distal end of the stylet tube51includes the flat surface50athat comes into contact with the receiving surface48of the distal end tip41as illustrated inFIG. 5. The stylet tube51has a relatively high rigidity, and has a stiffness to enable pushing force toward the distal end side, applied by an operation with the hand, to be transmitted to the distal end tip41. Thus, the stylet tube51has a function of expanding the catheter tube31in the longitudinal direction and dilating a narrow blood vessel, by bringing the flat surface50aof the stylet tube51to contact with the receiving surface48of the distal end tip41and pushing the distal end tip41toward the distal end side.

The stylet hub52is arranged on the proximal end side of the catheter30when the catheter30is coupled to the stylet50. As illustrated inFIG. 7, the stylet hub52includes an extending portion52A extending along a first enclosing portion53B of the coupling member53described later, on the outer side of the stylet hub52in the circumferential direction. The extending portion52A is formed to have a hollow circular shape in a cross section intersecting the longitudinal direction which receives a proximal end of the straight connector36.

As illustrated inFIG. 7, the coupling member53includes the first enclosing portion53B that extends in the longitudinal direction so as to enclose a section between the attachment portion53A attached to the stylet hub52and the male screw portion36A (engagement portion). The extending portion52A extends along the first enclosing portion53B and comes into contact with the male screw portion36A (engagement portion). When the male screw portion36A and the extending portion52A come into surface contact with each other, a sealing portion55sealing the proximal end side of the catheter30is formed between the catheter30and the stylet50.

The coupling member53includes the female screw portion53C that is provided on the distal end side of the first enclosing portion53B and is screwed with the male screw portion36A. The female screw portion53C is configured to be engageable with the male screw portion36A by rotating the coupling member53relatively with respect to the straight connector36.

Next, how the catheter assembly100described above is used will be described.FIG. 2illustrates a state before the stylet tube51of the stylet50is inserted into the lumen30A of the catheter30, andFIG. 4illustrates a state after the stylet tube51has been inserted into the lumen30A of the catheter30.

An operator such as a physician first inserts the stylet tube51of the stylet50into the lumen30A of the catheter30as illustrated inFIG. 4. As a result, the stylet tube51passes through the inside of the straight connector36, the clamp tube34, the catheter connector35, the second tube33, and the first tube32in this order. Then, the flat surface50aof the stylet tube51comes into contact with the receiving surface48of the distal end tip41(seeFIG. 5).

The total length of the stylet tube51along the axial direction is configured to be longer than the total length of the catheter30along the axial direction as illustrated inFIG. 2. Thus, the distal end tip41is pressed toward the distal end side, with the flat surface50aof the stylet tube51being in contact with the receiving surface48of the distal end tip41. As a result, the distal end of the first tube32fixed to the distal end tip41is pulled toward the distal end side.

Thus, the catheter30receives force in the expanding direction, and the first tube32, which is a relatively elastic portion of the catheter30, expands in the axial direction. When the first tube32expands in the axial direction, the outer diameter of the first tube32decrease to be substantially the same as the outer diameter of the second tube33. With the first tube32expanding in the axial direction, the proximal end of the catheter30and the stylet hub52are fixed to each other. The proximal end of the catheter30and the stylet hub52are fixed to each other, when the female screw portion53C and the male screw portion36A engage with each other due to a manual rotation of the coupling member53.

Next, the operator inserts the catheter30through which the stylet tube51is inserted, along a guide wire (not illustrated) that has been inserted into the target portion in the living body in advance. In this processing, by inserting the stylet50into the catheter30, the outer diameter of the first tube32becomes substantially the same as the outer diameter of the second tube33. Therefore, the catheter30can be inserted into the living body in a minimally invasive manner. The operator inserts the catheter30into the living body until the through holes46and47of the distal end tip41are placed in the right atrium and the side hole63is placed in the inferior vena cava, and holds the catheter30in this state. In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is arranged in the inferior vena cava which is a relative thick blood vessel, and the second tube33is arranged in the femoral vein which is a relatively thin blood vessel.

The operator then removes the stylet tube51and the guide wire from the catheter30by unscrewing coupling member53from straight connector36. In this process, the stylet tube51and the guide wire are first pulled out to a position of the straight connector36of the catheter30, temporarily clamped by forceps (not illustrated), and then is completely removed from the catheter30. When the stylet tube51is removed from the lumen30A of the catheter30, the catheter30is released from force in a direction for causing it to expand in the axial direction, received from the stylet50. Therefore, the first tube32contracts in the axial direction, and the outer diameter and inner diameter of the first tube32increase. Thus, the pressure loss in the first tube32can be reduced.

Next, the operator connects the straight connector36of the catheter30to the blood removal tube11of the extracorporeal circulatory device1illustrated inFIG. 1. Once completion of the connection of the catheter on the blood transmission is confirmed, the forceps of the clamp tube34are released and extracorporeal circulation starts.

When the extracorporeal circulation ends, the operator removes the catheter30from the blood vessel and performs hemostatic repair on the insertion site through a surgical procedure if necessary.

As described above, the catheter assembly100according to the present embodiment includes the catheter30and the stylet50, and the sealing portion55sealing the proximal end side of the catheter30is provided between them. The catheter30includes the catheter tube31, the receiving surface48, and the straight connector36. The catheter tube31is formed to have an elongated shape, is provided with the lumen30A in which the blood can flow, and is configured to be expandable and contractible. The receiving surface48is provided in the distal end portion of the catheter tube31, and enables the catheter tube31to expand in the longitudinal direction by the contacting. The straight connector36is provided on the proximal end side of the catheter30and is configured to be capable of being coupled with the stylet50. The straight connector36includes the male screw portion36A that can be engaged with the stylet50. The stylet50is configured to be capable of being inserted into the lumen30A, allows the catheter tube31to expand in the longitudinal direction by coming into contact with the receiving surface48, and includes the stylet hub52and the coupling member53. The stylet hub52is arranged on the proximal end side of the catheter30. The coupling member53couples the stylet hub52and the straight connector36to each other, and is configured to be engageable with the male screw portion36A.

The sealing portion55sealing the proximal end side of the catheter30is provided between the catheter30and the stylet50, whereby sealing between the catheter30and the stylet50is reliably obtained.

The coupling member53includes the first enclosing portion53B that extends in the longitudinal direction so as to enclose a section between the attachment portion53A attached to the stylet hub52and the male screw portion36A of the straight connector36. The stylet hub52includes the extending portion52A formed in a circular shape in a cross section intersecting the longitudinal direction and extending along the first enclosing portion53B on the outer side of the stylet hub52in the circumferential direction. The sealing portion55can be formed by surface contact between the male screw portion36A and the extending portion52A.

First Modification

Next, a catheter assembly100A according to a first modification will be described with reference toFIG. 8.FIGS. 8 to 12are diagrams used for a description on a main part of the catheter assembly100A according to the first modification.

As illustrated inFIG. 8, the catheter assembly100A according to the first modification is different from the first embodiment in that it includes a straight connector36B forming a catheter30B and a stylet hub520forming a stylet50A. The other configurations are substantially the same as those in the first embodiment, and the description to be redundant herein is basically omitted.

The straight connector36B has a proximal end portion36C that is formed more linearly than the proximal end portion of the straight connector36. The straight connector36B has a circular shape in a cross section intersecting the longitudinal direction in the proximal end portion36C, as in the case of the straight connector36of the first embodiment.

The stylet hub520includes the second enclosing portion520A capable of surrounding the proximal end portion36C of the straight connector36, on the outer circumference of the straight connector36. The second enclosing portion520A is configured to be capable of coming into contact with the outer side surface of the proximal end portion36C of the straight connector36B.

The second enclosing portion520A and the outer side surface of the proximal end portion36C of the straight connector36B may be in surface contact with each other while being inclined in substantially the same manner with respect to the longitudinal direction as illustrated inFIG. 9andFIG. 10, and thus a sealing portion550sealing the proximal end side of the catheter30may be formed.

This configuration should not be construed in a limiting sense. For example, a second enclosing portion520C of the stylet hub520B and the outer side surface of the proximal end portion36C of the straight connector36B may be different from each other in the inclination with respect to the longitudinal direction as illustrated inFIG. 11andFIG. 12. In this case, at least one of the two is deformed at a portion with different inclinations so that they are in circumferential surface contact with each other around the longitudinal direction. Thus, a sealing portion550A is formed at the portion of the surface contact.

As described above, the straight connector36has a circular shape in a cross section intersecting the longitudinal direction in the proximal end portion in the first modification. The stylet hub52includes the second enclosing portion520A capable of surrounding the proximal end portion of the straight connector36, on the outer circumference of the straight connector36, and capable of coming into contact with the outer side surface of the proximal end portion of the straight connector36. The sealing portion550can also be formed by surface contact between the second enclosing portion520A and the outer side surface of the straight connector36.

When the sealing portion550is formed with the second enclosing portion520A being in contact with the outer side surface of the proximal end portion36C of the straight connector36B as in the present first modification, no contact occurs on the inner circumference surface of the straight connector36B. Thus, when surface treatment such as polymer coating is provided on the inner circumference surface, such coating or the like can be prevented from peeling. The same applies to the sealing portion55in the first embodiment.

Second Modification

Next, a catheter assembly100B according to a second modification will be described with reference toFIG. 13.FIG. 13is a diagram used for a description on a main part of the catheter assembly100B according to the second modification.

The catheter assembly100B according to the second modification is, like the first modification, different from the first embodiment in that it includes a straight connector36D forming a catheter30C and a stylet hub521forming a stylet50B. Further, the straight connector36D of the second modification has a proximal end portion provided with a tapered surface36E formed in a tapered shape. The other configurations are substantially the same as in the first embodiment.

The stylet hub521includes a contact surface521A capable of coming into contact with the tapered surface36E, and the sealing portion551sealing the proximal end side of the catheter30is configured by surface contact between the tapered surface36E and the contact portion521A.

As described above, the straight connector36D in the second modification has the proximal end portion provided with the tapered surface36E formed in a tapered shape. The stylet hub521has the contact surface521A capable of coming into contact with the tapered surface36E of the straight connector36D. The sealing portion551can reliably obtain the sealing property as in the first embodiment or the like due to the surface contact between the tapered surface36E and the contact surface521A.

Fourth Embodiment

Next, the catheter assembly200according to a fourth embodiment of the present invention will be described with reference toFIGS. 14 to 16.FIGS. 14 to 16are diagrams used for a description on the configuration of the catheter assembly200according to the fourth embodiment. The catheter assembly200according to the present embodiment has the percutaneous catheter (hereinafter referred to as “catheter”)60different from that in the third embodiment.

This catheter60is what is known as a double lumen catheter configured to simultaneously enable both transmission and removal of blood. Thus, in the present embodiment, the catheter60is in charge of functions of two catheters, that is, the venous catheter (blood removal catheter)5and the arterial catheter (blood transmission catheter)6in the extracorporeal circulatory device1inFIG. 1.

The catheter60according to the present embodiment is different from the catheter30according to the first embodiment in that a double tube structure is provided as illustrated inFIGS. 15 and 16. In such a structure, a third tube161having a first lumen61in communication with a blood transmission side hole163is provided inside a lumen of the second tube33.

With the catheter60, the blood is removed from a vein (vena cava) of the patient with a pump of the extracorporeal circulatory device1activated. Thereafter, gas exchange inside the blood is performed with the artificial lung2to oxygenate the blood, and then the resultant blood is returned to the vein (vena cava) of the patient again. In this manner, the Veno-Venous (VV) procedure can be performed.

Hereinafter, each configuration of the catheter60will be described. The parts common to the first embodiment will be omitted, and characteristic parts of the present embodiment will be described. The parts having the same functions as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As illustrated inFIG. 15, the catheter60includes the first tube32, the second tube33, the distal end tip41that is provided at the distal end of the first tube32and includes the through holes46and47, and the third tube161provided inside the second tube33.

As illustrated inFIG. 15, the catheter60includes the first lumen61that functions as the blood transmission channel and a second lumen62that functions as the blood removal channel.

The first lumen61is formed inside the third tube161. The second lumen62is formed through the first tube32and the second tube33, from the distal end to the proximal end.

The second tube33includes the blood transmission side hole163in communication with the first lumen61that is the blood transmission channel and a blood removal side hole164in communication with the second lumen62that is the blood removal channel. The blood transmission side hole163and the blood removal side hole164are formed to have an elliptical shape, but are not limited this shape.

The third tube161is configured to be inserted into the second lumen62from the proximal end side of the second tube33and to be in communication with the blood transmission side hole163.

The blood transmission side hole163is arranged in the blood transmission target in the living body. The blood oxygenated by the artificial lung2is transmitted into the living body through the blood transmission side hole163.

The through holes46and47of the distal end tip41and blood removal side hole164are arranged in different blood removal targets in the living body so that blood can be efficiently removed. When the through hole46,47or the blood removal side hole164is closed as a result of being adsorbed on a blood vessel wall, blood can be removed through unclosed one of the holes, whereby extracorporeal circulation can be stably performed.

In the present embodiment, the catheter60is inserted from the internal jugular vein of the neck, passes through the superior vena cava and the right atrium, to have the distal end placed in the inferior vena cava. The blood transmission target is the right atrium, and the blood removal target includes two portions that are the superior vena cava and the inferior vena cava.

As illustrated inFIGS. 14 and 15, the catheter60is inserted, in a state where the stylet50is inserted, into the living body and is held once the through holes46and47of the distal end tip41are placed in the inferior vena cava and the blood removal side hole164is placed in the internal jugular vein.

As in the first embodiment, the first tube32is configured to have an inner diameter that is larger than that of the second tube33. In a state where the through holes46and47and the side hole63are arranged in the blood removal targets, the first tube32is placed in the inferior vena cava which is a relatively thick blood vessel, and the second tube33is placed in the femoral vein which is a relatively thin blood vessel.

As illustrated inFIG. 15, a straight connector136includes a first straight connector137and a second straight connector138. The first straight connector137is configured to communicate with the first lumen61, and the second straight connector138is configured to communicate with the second lumen62. The straight connector136is configured as a Y-shaped Y connector formed with the first straight connector137branched from the second straight connector138. For the sake of illustration, inFIG. 15, the first straight connector137and the second straight connector138are close to each other, but the first straight connector137and the second straight connector138are actually arranged to be more separated from each other by an amount larger than that illustrated inFIG. 15.

The first straight connector137is coupled to the proximal end portion of the third tube161. The second straight connector138is coaxially coupled to the proximal end portion of the second tube33. A blood transmission tube (blood transmission line) is connected to the first straight connector137, and a blood removal tube (blood removal line) is connected to the second straight connector138. The first straight connector137is provided with a male screw portion137A, and the second straight connector138is provided with a male screw portion138A.

The first tube32is configured to function in the same manner as in the first embodiment. When the stylet50is inserted into the catheter60, as illustrated inFIG. 16, the first tube32expands to have the outer diameter and the inner diameter reduced. As a result, the catheter60can be inserted into the living body in a minimally invasive manner. When the stylet50is removed from the catheter60, the first tube32is contracted in the axial direction to have the inner diameter increased as illustrated inFIG. 14. Thus, the pressure loss inside the first tube32can be reduced.

As described above, the catheter assembly200of the present embodiment has the catheter60. Thus, both blood removal and blood transmission functions can be provided with a single catheter.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. The embodiments and the like in which the catheter30includes the straight connector36have been described above. However, the type of the connector is not limited to the straight connector as long as a sealing portion can be formed and the connector can be connected to a mating component.