STYLET FOR A PERCUTANEOUS CATHETER

A catheter system insertable into a living body to convey blood has a catheter tube and a stylet. The catheter tube has an expansion portion, a shaft portion, and a lumen. The stylet includes an outer peripheral member that extends in an axial direction and has an outer diameter the same as an inner diameter of the shaft portion, an inner peripheral member provided with an exposed portion exposed from a distal end of the outer peripheral member and provided on an inner periphery of the outer peripheral member so as to be slidable with respect to the outer peripheral member, and a fitting stopper into which a fitting member on an outer periphery of a proximal end of the outer peripheral member is fittable. A region is formed in the fitting stopper in which the outer peripheral member and the fitting member are movable.

BACKGROUND OF THE INVENTION

The present invention relates to a stylet and a catheter system with the stylet.

Conventionally, treatment by percutaneous cardiopulmonary support (PCPS) has been performed in order to perform cardiopulmonary resuscitation, circulation assistance, and respiration assistance in emergency treatment. The percutaneous cardiopulmonary support is a method of temporarily assisting and substituting for a cardiopulmonary function using an extracorporeal circulation device.

The extracorporeal circulation device is provided with an extracorporeal circulation circuit formed of a centrifugal pump, an oxygenator, a blood removal path, a blood supply path and the like, and performs gas exchange on removed blood and supplies the blood to the blood supply path.

In a case where blood circulation is performed by the circulation circuit, the blood is circulated by a force of the pump driven by a motor. Therefore, in order to suitably perform the blood circulation, it is required to alleviate a pressure loss in a tube forming the circulation circuit.

Note that, when an inner diameter of the tube is small, the pressure loss increases, and a flow rate flowing through the circulation circuit decreases. Therefore, unless the inner diameter of the tube is set to a sufficient size, a required circulation amount of blood cannot be obtained.

In contrast, when the inner diameter of the tube is increased, an outer diameter of the tube is also increased. Therefore, when inner diameters of a blood removal catheter (tube) and a blood supply catheter (tube) inserted into a body of a patient are increased, a degree of invasion on the body of the patient increases, and a burden on the body of the patient increases.

In connection with this, for example, U.S. Patent Application Publication 2002/0010440A1 discloses a high-performance cannula capable of axially extending or contracting a cannula body (catheter) by a mandrel (stylet) to increase or decrease a diameter. According to the high-performance cannula formed in this manner, by inserting the same into a living body in a state in which the cannula body is extended in the axial direction and the diameter (outer diameter) is decreased by the mandrel, the degree of invasion on the body of the patient is decreased. Moreover, by removing the mandrel after completing the insertion of the high-performance cannula into the living body, the cannula body contracts in the axial direction to increase the diameter (inner diameter). Therefore, the pressure loss in the catheter is decreased, and a required flow rate of liquid may be secured.

In the high-performance cannula disclosed in US2002/0010440A1, when the stylet is inserted into the catheter, a distal terminal end (expansion portion) of the catheter is extended in the axial direction and the catheter is contracted radially inward. At that time, an insertion point (shaft portion) of the catheter tube which receives the stylet and which is located proximally of the catheter expansion portion might also become extended in the axial direction and likewise contracts radially inward. When the shaft portion contracts radially inward in this manner, it can contact with the stylet so that frictional resistance with the stylet increases, whereby the stylet cannot be inserted fully to a desired position, and the expansion portion does not completely contract radially inward. If this is inserted into the living body in a state in which the expansion portion does not completely contract radially inward, the degree of invasion on the body of the patient increases, which is not preferable.

SUMMARY OF THE INVENTION

The present invention is achieved to solve the above-described problem, and an object thereof is to provide a stylet capable of suitably contracting an expansion portion radially inward when being inserted into a catheter.

A stylet that achieves the above-described object is a stylet formed to be insertable into a tube provided with an expandable expansion portion, a shaft portion provided at a proximal end of the expansion portion, and a lumen through which blood may flow, the stylet capable of extending the expansion portion in an axial direction. The stylet includes an outer peripheral member that extends in the axial direction and has an outer diameter the same as an inner diameter of the shaft portion, an inner peripheral member provided with an exposed portion exposed from a distal end of the outer peripheral member and provided on an inner periphery of the outer peripheral member so as to be slidable with respect to the outer peripheral member, a fitting member joined to an outer periphery of the outer peripheral member at a proximal end of the outer peripheral member, and a fitting stopper defining an inner region in which the outer peripheral member and the fitting member are movable over a length in the axial direction corresponding to an extension length of the expansion portion. Since the outer peripheral member has an outer diameter conformable to an inner diameter of the shaft portion and has an inner passage defined by an inner periphery of the outer peripheral member in which the inner peripheral member is received, the inner peripheral member is slidable without frictional resistance.

According to the stylet formed in the above-described manner, when the stylet is inserted into the tube, the shaft portion is about to contract radially inward, but the shaft portion comes into contact with the outer peripheral member, the contraction of the shaft portion radially inward is regulated, and the outer peripheral member does not move in the axial direction due to friction. In this state, by moving the inner peripheral member toward the distal end side with respect to the outer peripheral member, the expansion portion of the tube extends in the axial direction and suitably contracts radially inward. From above, at the time of insertion into the catheter, the expansion portion may be suitably contracted radially inward.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the present invention is hereinafter described with reference to the accompanying drawings. Note that, the following description does not limit the technical scope or meaning of terms recited in claims. Dimensional ratios in the drawings are exaggerated for convenience of description, and might be different from actual ratios.

FIG.1is a system diagram illustrating an example of an extracorporeal circulation device to which a percutaneous catheter according to the embodiment of the present invention is applied, the extracorporeal circulation device used as percutaneous cardiopulmonary support (PCPS) that temporarily assists and substitutes for functions of the heart and lungs until a heart function recovers when the heart of a patient is weak.

According to an extracorporeal circulation device1, it is possible to perform a veno-arterial (VA) procedure of removing blood from a vein (vena cava) of the patient by operating a pump, exchanging gas in the blood by an oxygenator to oxygenate the blood, and then returning the blood to an artery (aorta) of the patient again. The extracorporeal circulation device1is a device that assists the heart and lungs. Hereinafter, a procedure of removing the blood from the patient, performing predetermined extracorporeal treatment, and then supplying the blood into the body of the patient again is referred to as “extracorporeal circulation”.

As illustrated inFIG.1, the extracorporeal circulation device1includes a circulation circuit that circulates the blood. The circulation circuit includes an oxygenator2, a centrifugal pump3, a drive motor4as a drive means for driving the centrifugal pump3, a vein-side catheter (percutaneous catheter for blood removal)5, an artery-side catheter (blood supply catheter)6, and a controller10as a control unit.

The vein-side catheter (blood removal catheter)5is inserted from the femoral vein, and a distal end of the vein-side catheter5is indwelled in the right atrium via the inferior vena cava. The vein-side catheter5is connected to the centrifugal pump3via a blood removal tube (blood removal line)11. The blood removal tube11is a pipeline that sends the blood.

The artery-side catheter (blood supply catheter)6is inserted from the femoral artery.

When the drive motor4operates the centrifugal pump3by a command SG of the controller10, the centrifugal pump3may remove the blood from the blood removal tube11and pass the blood via the oxygenator2, then return the blood to a patient P through a blood supply tube (blood supply catheter)12.

The oxygenator2is arranged between the centrifugal pump3and the blood supply tube12. The oxygenator2performs gas exchange (oxygenation and/or carbon dioxide removal) on the blood. The oxygenator2is, for example, a membrane oxygenator, and a hollow fiber membrane oxygenator is especially preferably used. Oxygen gas is supplied from an oxygen gas supply unit13to the oxygenator2via a tube14. The blood supply tube12is a pipeline that connects the oxygenator2to the artery-side catheter6.

As the blood removal tube11and the blood supply tube12, for example, a pipeline made of an elastically deformable and flexible synthetic resin having high transparency such as a vinyl chloride resin or silicone rubber may be used. In the blood removal tube11, the blood as liquid flows in a V1direction, and in the blood supply tube12, the blood flows in a V2direction.

In the circulation circuit illustrated inFIG.1, an ultrasonic bubble detection sensor20is arranged in the middle of the blood removal tube11. A fast clamp17is arranged in the middle of the blood supply tube12.

In a case where a bubble is mixed in the circulation circuit with the blood due to an erroneous operation of a three-way stopcock18or a breakage of the tube and the like during the extracorporeal circulation, then the ultrasonic bubble detection sensor20detects the mixed bubble. In a case where the ultrasonic bubble detection sensor20detects that there is the bubble in the blood sent in the blood removal tube11, the ultrasonic bubble detection sensor20transmits a detection signal to the controller10. On the basis of this detection signal, the controller10performs notification of a warning by an alarm, and decreases a rotation speed of the centrifugal pump3or stops the centrifugal pump3. The controller10further instructs the fast clamp17to immediately close the blood supply tube12by the fast clamp17. This prevents the bubble from being sent into the body of the patient P. The controller10controls an operation of the extracorporeal circulation device1to prevent mixing of the bubble into the body of the patient P.

The tube11(tube12,19) of the circulation circuit of the extracorporeal circulation device1is provided with a pressure sensor. For example, the pressure sensor may be attached to any one or all of an attachment position A1of the blood removal tube11, an attachment position A2of the blood supply tube12of the circulation circuit, and an attachment position A3of a connection tube19that connects the centrifugal pump3to the oxygenator2. As a result, a pressure in the tube11(12,19) may be measured by the pressure sensor when the extracorporeal circulation is performed on the patient P by the extracorporeal circulation device1. Note that, the attachment position of the pressure sensor is not limited to the attachment positions A1, A2, and A3described above, and may be any position of the circulation circuit.

Next, a configuration of a percutaneous catheter (hereinafter, referred to as a “catheter”)30into which a stylet50according to the embodiment of the present invention is inserted is described with reference toFIGS.2to5B.FIGS.2to5Bare views for describing the configuration of the catheter30. The catheter30is used as the vein-side catheter (blood removal catheter)5inFIG.1. Note that, the configuration of the catheter30described below is an example, and the configuration of the catheter into which the stylet50according to this embodiment is inserted is not limited to the following configuration.

As illustrated inFIG.2, the catheter30includes a catheter tube31provided with a first side hole63and a second side hole46, a distal end tip41arranged at a distal end of the catheter tube31and provided with a through-hole47, a clamping tube34arranged on a proximal end side of the catheter tube31, a catheter connector35that connects the catheter tube31to the clamping tube34, and a lock connector36.

Note that, in this specification, a side to be inserted into a living body is referred to as a “distal end” or a “distal end side”, and a hand side operated by an operator is referred to as a “proximal end” or a “proximal end side”. A distal end part means a certain range including the distal end (most distal end) and its periphery, and a proximal end part means a certain range including the proximal end (most proximal end) and its periphery.

As illustrated inFIG.3, the catheter30includes a lumen30A penetrating from a distal end to a proximal end thereof. The through-hole47provided on the distal end tip41, and the first and second side holes63and46provided on the catheter tube31are arranged in different blood removal targets in the living body such that the blood may be efficiently removed.

When the catheter30is inserted into the living body, the stylet50illustrated inFIG.2is used. The stylet50is inserted into the lumen30A of the catheter30, and the catheter30and the stylet50are inserted together into the living body in a state of being integrated in advance.

Hereinafter, each configuration of the catheter30is described. Note that, the configuration of the catheter30is not limited to the following.

As illustrated inFIG.2, the catheter tube31includes an expansion portion32and a shaft portion33connected to a proximal end side of the expansion portion32.

The expansion portion32is formed to have higher elasticity than that of the shaft portion33. The expansion portion32is formed to have larger outer and inner diameters than those of the shaft portion33.

Lengths of the expansion portion32and the shaft portion33are set to lengths necessary for arranging the through-hole47of the distal end tip41and the first and second side holes63and46of the catheter tube31in desired blood removal targets. The length of the expansion portion32may be set to, for example, 20 to 40 cm, and the length of the shaft portion33may be set to, for example, 20 to 30 cm.

In this embodiment, the blood removal targets are two sites: the right atrium and the inferior vena cava. The catheter30is inserted into the living body to be indwelled there such that the through-hole47of the distal end tip41and the second side hole46of the catheter tube31are arranged in the right atrium, and the first side hole63of the catheter tube31is arranged in the inferior vena cava.

In a state in which the through-hole47, the second side hole46, and the first side hole63are arranged in the blood removal targets, the expansion portion32is arranged in the inferior vena cava, which is a relatively large blood vessel, and the shaft portion33is arranged in the femoral vein, which is a relatively small blood vessel.

When the stylet50is inserted into the lumen30A of the catheter30, the expansion portion32having high elasticity extends in an axial direction and the outer and inner diameters thereof decrease as illustrated inFIG.4. At that time, the outer diameter of the expansion portion32is substantially the same as the outer diameter of the shaft portion33. Since the catheter30is inserted into the living body in a state in which the expansion portion32is extended in the axial direction and the outer and inner diameters thereof decrease, the catheter30may be inserted in a minimally invasive manner.

When the stylet50is removed from the lumen30A of the catheter30after the catheter30is indwelled in the living body, the expansion portion32contracts from the state of being extended in the axial direction so that it will return to a larger inner diameter. Herein, the expansion portion32is arranged in the inferior vena cava, which is a relatively large blood vessel. Therefore, the outer diameter of the expansion portion32may be increased, and accordingly, the inner diameter may be increased.

Herein, a pressure loss in the expansion portion32is obtained by a total length of the expansion portion32×(average) passage cross-sectional area. That is, by increasing the inner diameter of the expansion portion32, the pressure loss in the expansion portion32is decreased. When the pressure loss in the expansion portion32is decreased, a flow rate of the blood flowing through the circulation circuit increases. Therefore, in order to obtain a sufficient blood circulation amount, it is necessary to increase the inner diameter of the expansion portion32.

In contrast, in a case where a wall thickness is substantially constant, when the inner diameters of the expansion portion32and the shaft portion33are increased, the outer diameters increase, so that a burden on the patient increases when the catheter30is inserted into the living body, which hinders a minimally invasive procedure.

From the above-described viewpoint, the inner diameter of the expansion portion32may be set to, for example, 9 to 11 mm, and the inner diameter of the shaft portion33may be set to, for example, 4 to 8 mm. The wall thickness of each of the expansion portion32and the shaft portion33may be set to, for example, 0.4 to 0.5 mm.

As illustrated inFIG.2, it is preferable that a distal end part of the expansion portion32forms a tapered portion that gradually becomes thinner from the center of the expansion portion32toward a distal end side in the axial direction. As a result, the inner diameter of a distal end of the expansion portion32is continuous to an inner diameter of the distal end tip41arranged on the distal end side thereof.

As illustrated inFIG.5A, the expansion portion32includes a first reinforcing body321including wires W braided so as to cross each other, and a first resin layer322provided so as to cover the first reinforcing body321.

As illustrated inFIG.5B, the shaft portion33includes a second reinforcing body331including wires W braided so as to cross each other, and a second resin layer332provided so as to cover the second reinforcing body331.

As illustrated inFIG.5A, the first reinforcing body321is formed by braiding the wires W to form a braiding angle θ1. As illustrated inFIG.5B, the second reinforcing body331is formed by braiding the wires W to form a braiding angle82.

In this specification, the braiding angles θ1and θ2are defined as inner angles in the axial direction out of the angles formed by the crossing wires W, as illustrated inFIGS.5A and5B.

As illustrated inFIGS.5A and5B, the braiding angle θ1of the first reinforcing body321is made smaller than the braiding angle θ2of the second reinforcing body331. Therefore, an inclination angle of the wire W forming the first reinforcing body321with respect to the axial direction is smaller than that in a case where the braiding angle of the first reinforcing body321is larger than the braiding angle of the second reinforcing body331. Note that, the braiding angle θ1of the first reinforcing body321may be made larger than the braiding angle θ2of the second reinforcing body331.

Herein, as the expansion portion32extends in the axial direction, the wire W forming the first reinforcing body321of the expansion portion32is deformed such that the inclination angle with respect to the axial direction gradually decreases. When the inclination angle of the wire W forming the first reinforcing body321of the expansion portion32with respect to the axial direction becomes approximately 0, the extension of the expansion portion32in the axial direction is regulated.

Therefore, by making the braiding angle θ1of the first reinforcing body321smaller than the braiding angle θ2of the second reinforcing body331, as compared with a case where the braiding angle of the first reinforcing body321is larger than the braiding angle of the second reinforcing body331, an extension distance in the axial direction of the expansion portion32accompanying the insertion of the stylet50into the catheter30is shortened.

The braiding angle θ1of the first reinforcing body321is not especially limited, but is 100 to 120 degrees. The braiding angle θ2of the second reinforcing body331is not especially limited, but is 130 to 150 degrees. By making the braiding angle θ2of the second reinforcing body331larger than the braiding angle θ1of the first reinforcing body321in this manner, kink resistance of the second reinforcing body331may be improved. Therefore, the catheter30may be suitably inserted into the living body in the femoral vein having a complicated configuration.

As illustrated inFIGS.5A and5B, the first reinforcing body321of the expansion portion32is braided sparser than the second reinforcing body331of the shaft portion33. According to this configuration, the expansion portion32may be made softer than the shaft portion33, and elasticity may be enhanced.

In this embodiment, the wire W is formed of a well-known shape memory material of shape memory metal or a shape memory resin. As the shape memory metal, for example, a titanium-based (Ni—Ti, Ti—Pd, Ti—Nb—Sn and the like) or copper-based alloy may be used. As the shape memory resin, for example, an acrylic resin, a transisoprene polymer, polynorbornene, a styrene-butadiene copolymer, and polyurethane may be used.

Since the wire W is formed of the shape memory material, a contraction distance in the axial direction of the expansion portion32accompanying the removal of the stylet50from the catheter30is the same as the extension distance in the axial direction of the expansion portion32accompanying the insertion of the stylet50into the catheter30.

A diameter of the wire W is preferably 0.1 to 0.2 mm.

By setting the diameter of the wire W to 0.1 mm or larger, a function as the reinforcing body for improving strength may be suitably exhibited.

In contrast, by setting the diameter of the wire W to 0.2 mm or smaller, the inner diameter of the expansion portion32may be increased while decreasing the outer diameter thereof, so that it is possible to achieve both suppression in burden on the body of the patient at the time of insertion of the catheter30and decrease in pressure loss. In this embodiment, a cross section of the wire W is circular, but is not limited thereto, and may be rectangular, square, elliptical and the like.

The first resin layer322of the expansion portion32is formed of a soft material having hardness lower than that of the second resin layer332of the shaft portion33. According to this configuration, the expansion portion32may be made softer than the shaft portion33, and elasticity may be enhanced.

The first and second resin layers322and332may be formed using vinyl chloride, silicon, polyethylene, nylon, urethane, polyurethane, a fluororesin, a thermoplastic elastomer resin and the like, or a composite material thereof.

The silicon material has high biocompatibility, and the material itself is soft, so that this has an advantage that this does not easily damage a blood vessel. The polyethylene material is soft and has hardness to withstand a pressure. Moreover, the polyethylene material has biocompatibility comparable to that of the silicon material. The polyethylene material is harder than silicon, and has an advantage that this is easily inserted into a thin blood vessel. The polyurethane material has an advantage that this becomes soft after insertion. As the materials of the first and second resin layers322and332, applicable materials may be used by using the advantages of these materials.

A hydrophilic coating may be applied to the polyurethane material. In this case, since a tube surface is smooth, this may be easily inserted into the blood vessel, and the blood vessel wall is less likely to be damaged. The blood and proteins are less likely to adhere, and it may be expected that thrombus formation is prevented.

A method of forming the expansion portion32and the shaft portion33is not especially limited, but they may be formed by, for example, dip coating (immersion method), insert molding and the like. Note that, it is sufficient that at least outer surfaces of the reinforcing bodies321and331are covered with the resin layers322and332, respectively.

As illustrated inFIG.2, the expansion portion32includes the second side hole46. As illustrated inFIG.2, a plurality of (four inFIG.2) second side holes46is provided in the axial direction. A plurality of second side holes46is preferably provided also in a circumferential direction. The second side hole46serves as a blood removal hole.

As illustrated inFIG.2, the shaft portion33includes the first side hole63. The first side hole63serves as a blood removal hole. A plurality of first side holes63is preferably provided in a circumferential direction. In this embodiment, the shaft portion33is provided with four first side holes63in the circumferential direction. As a result, even if one first side hole63is adsorbed to the blood vessel wall and blocked by the blood removal, the blood removal may be performed by another first side hole63, so that blood circulation may be stably performed.

As illustrated inFIGS.2to4, the distal end tip41is arranged at the distal end of the expansion portion32. The distal end tip41has a tapered shape a diameter of which is gradually decreased toward the distal end side.

A flat receiving surface48that abuts a flat surface52aof the stylet50used before the catheter30is inserted into the living body is formed inside the distal end tip41.

As illustrated inFIG.3, the distal end tip41is formed to house a distal end of the wire W. The distal end tip41includes the through-hole47. The through-hole47serves as a blood removal hole. The through-hole47of the distal end tip41forms a part of the lumen30A of the catheter30. The distal end tip41may be formed of, for example, urethane.

By fixing a hard distal end tip41to the distal end part of the expansion portion32, it is possible to effectively prevent the expansion portion32from being crushed at the time of blood removal.

As illustrated inFIGS.2to4, the clamping tube34is provided on a proximal end side of the shaft portion33. A lumen into which the stylet50may be inserted is provided inside the clamping tube34. The clamping tube34may be formed using a material similar to that of the catheter tube31.

As illustrated inFIGS.2and4, the catheter connector35connects the shaft portion33to the clamping tube34. A lumen into which the stylet50may be inserted is provided inside the catheter connector35.

As illustrated inFIGS.2to4, the lock connector36is connected to a proximal end side of the clamping tube34. A lumen into which the stylet50may be inserted is provided inside the lock connector36. A male screw portion36A provided with a screw thread is provided on an outer surface on a proximal end side of the lock connector36.

Next, a configuration of the stylet50according to this embodiment is described with reference toFIG.6and the like.FIG.6is a view for describing the configuration of the stylet50according to this embodiment.

As illustrated inFIG.6, the stylet50includes an outer peripheral member51that extends in the axial direction, an inner peripheral member52provided on an inner periphery of the outer peripheral member51, a fitting member53joined to an outer periphery of a proximal end of the outer peripheral member51, and a fitting stopper54into which the fitting member53may be fitted.

An outer diameter of the outer peripheral member51is formed so as to be the same as the inner diameter of the shaft portion33. Note that, the fact that this is the same as the inner diameter of the shaft portion33not only indicates that they are completely the same but also includes some tolerance error.

As illustrated inFIG.6, a distal end part51A of the outer peripheral member51is tapered such that the outer diameter gradually decreases toward a distal end from the outer peripheral member51toward the inner peripheral member52. According to this configuration, since the outer periphery of the distal end part51A of the outer peripheral member51has a gentle tapered shape, the catheter30has a smooth transitional shape without a step following the shape of the distal end part51A in a state in which the stylet50is inserted into and integrated with the catheter30. Therefore, insertability of the catheter30into the living body is improved.

An inner diameter of the outer peripheral member51is formed to be slightly larger than an outer diameter of the inner peripheral member52. Therefore, the inner peripheral member52is slidable in the axial direction (right-left direction inFIG.6) with respect to the outer peripheral member51within an inner passage of outer peripheral member51.

The outer peripheral member51is an elongated body having relatively high rigidity. A material forming the outer peripheral member51is not especially limited, but the material similar to that of the first and second resin layers322and332described above may be used.

The inner peripheral member52is provided on the inner periphery of the outer peripheral member51so as to be slidable with respect to the outer peripheral member51. As illustrated inFIG.6, the inner peripheral member52includes an exposed portion52A exposed from the distal end of the outer peripheral member51.

A length in the axial direction of the exposed portion52A is preferably the same as or shorter than the length in the axial direction of the expansion portion32before being extended. According to this configuration, the expansion portion32may be suitably contracted radially inward.

An entire length in the axial direction of the inner peripheral member52is formed to be longer than an entire length in the axial direction of the catheter30before the expansion portion32is extended. In other words, the entire length in the axial direction of the inner peripheral member52is formed to be the same as the entire length in the axial direction of the catheter30after the expansion portion32becomes extended.

The inner peripheral member52is provided with a guidewire lumen52B into which a guidewire (not illustrated) may be inserted. The outer peripheral member51and the inner peripheral member52are guided by the guide wire to be inserted into the living body together with the catheter30.

As illustrated inFIG.2, a distal end of the inner peripheral member52is provided with the flat surface52athat the receiving surface of the distal end tip41abuts when inserted. The inner peripheral member52is formed such that the outer diameter and an inner diameter are uniform in the axial direction.

The inner peripheral member52is an elongated body having relatively high rigidity. The inner peripheral member52is preferably formed of a material softer than that of the outer peripheral member51. A material forming the inner peripheral member52is not especially limited, but the material similar to that of the first and second resin layers322and332described above may be used. According to this configuration, it is possible to relatively increase rigidity of a proximal end of the stylet50while softening a distal end of the stylet50. Therefore, when the stylet50and the catheter30are inserted into the living body, it is possible to prevent living tissue from being damaged, and stiffness that enables transmission of a pushing force to the distal end side by a hand side operation to the distal end tip41is provided.

As illustrated inFIG.6, the fitting member53is joined to the outer periphery of the proximal end of the outer peripheral member51. A method of joining the fitting member53to the outer peripheral member51is not especially limited, and is, for example, adhesion using an adhesive.

The fitting member53is formed of, for example, rubber, and has elasticity. Note that, a material forming the fitting member53is not limited to rubber, and may be any material that may be strongly fitted into a fitted portion54A. The fitting member53is formed to be fittable into the fitted portion54A of the fitting stopper54to be described later. That is, an outer diameter of the fitting member53is formed to be slightly larger than an inner diameter of the fitted portion54A of the fitting stopper54.

As illustrated inFIG.6, the fitting stopper54is provided at the proximal end of the stylet50. As illustrated inFIG.6, the fitting stopper54includes the fitted portion54A, a hub54B, and a screw ring54C.

The fitted portion54A is provided on a proximal end side of the screw ring54C. The fitted portion54A is a lumen having the inner diameter smaller than the outer diameter of the fitting member53.

The hub54B is provided at a proximal end of the fitting stopper54so as to be grippable. After the catheter30is indwelled in the living body, the stylet50is removed from the catheter30by pulling out the hub54B to the proximal end side.

The screw ring54C includes a female screw portion (not illustrated) provided with a screw groove on an inner surface of an inner cavity. The stylet50may be attached to the catheter30by screwing the female screw portion of the screw ring54C into the male screw portion36A of the lock connector36.

Moreover, the fitting stopper54includes a region54D in which the outer peripheral member51and the fitting member53are movable between the fitted portion54A and the hub54B. A length in the axial direction of the region54D is made the same as an extension length of the remaining expansion portion32when the shaft portion33starts contracting. According to this configuration, the expansion portion23may be suitably contracted radially inward.

<Method of Using Stylet>

Next, a method of using the above-described stylet50is described with reference toFIGS.7A to7C.FIGS.7A to7Care views for describing the method of using the stylet50according to this embodiment.

First, as illustrated inFIG.7A, the stylet50is inserted into the lumen30A of the catheter30in preparation for insertion into a living body. The stylet50sequentially passes through the inside of the shaft portion33and the expansion portion32, until the flat surface52aof the inner peripheral member52of the stylet50abuts the receiving surface48of the distal end tip41.

Herein, the entire length in the axial direction of the outer peripheral member51and the inner peripheral member52is made longer than the entire length in the axial direction of the catheter30before the expansion portion32becomes extended as illustrated inFIG.2. Therefore, the expansion portion32is pressed toward the distal end side in a state in which the flat surface52aof the inner peripheral member52of the stylet50abuts the receiving surface48of the distal end tip41.

Then, the distal end of the expansion portion32is pulled toward the distal end side as illustrated inFIG.7B. As a result, the catheter30receives a force to extend in the axial direction, and the expansion portion32having relatively high elasticity out of the catheter30extends (stretches) in the axial direction. The shaft portion33would also tend to contract radially inward, but the shaft portion33comes into contact with the outer peripheral member51so that contraction of the shaft portion33radially inward is regulated, and the outer peripheral member51does not move in the axial direction due to friction. In this state, by moving the inner peripheral member52toward the distal end side with respect to the outer peripheral member51, the expansion portion32extends in the axial direction and suitably contracts radially inward without being hindered by the friction. At that time of relative movement between outer peripheral member51and inner peripheral member52, the fitting member53fitted into the fitted portion54A of the fitting stopper54is displaced from the fitted portion54A.

Thereafter, the stylet50is attached to the catheter30by screwing the female screw portion of the screw ring54C into the male screw portion36A provided on the lock connector36of the catheter as illustrated inFIG.7C. At that time, as illustrated inFIG.7C, the proximal ends of the fitting member53and the outer peripheral member51abut a proximal end of the region54D of the fitting stopper54.

Next, the catheter30into which the stylet50is inserted is inserted along the guide wire (not illustrated) inserted in advance into a target site in the living body. At that time, since the stylet50is inserted into the catheter30, the outer diameter of the expansion portion32is substantially the same as the outer diameter of the shaft portion33, and the catheter30may be inserted into the living body in a minimally invasive manner, and the burden on the body of the patient may be suppressed.

The catheter30is inserted into the living body until the through-hole47of the distal end tip41and the second side hole46of the catheter tube31are arranged in the right atrium and the first side hole63of the catheter tube31is arranged in the inferior vena cava to be indwelled there. In a state in which the through-hole47, the first side hole63, and the second side hole46are arranged in the blood removal targets, the expansion portion32is arranged in the inferior vena cava, which is a relatively large blood vessel, and the shaft portion33is arranged in the femoral vein, which is a relatively small blood vessel.

Next, the stylet50and the guide wire are removed from the catheter30. At that time, the stylet50and the guide wire are temporarily pulled out to a site of the clamping tube34of the catheter30and clamped by forceps (not illustrated), and then completely removed from the catheter30. When the stylet50is removed from the lumen of the catheter30, the catheter30is released from the force to axially extend that the catheter30receives from the stylet50. Therefore, the expansion portion32contracts in the axial direction, and the inner diameter of the expansion portion32increases. As a result, the pressure loss in the expansion portion32may be decreased, and a required flow rate of liquid may be secured.

Next, the lock connector36of the catheter30is connected to the blood removal tube11of the extracorporeal circulation device inFIG.1. After confirming that the connection of the catheter on the blood supply side is completed, the forceps of the clamping tube34are released to start the extracorporeal circulation.

When the extracorporeal circulation ends, the catheter30is removed from the blood vessel and hemostatic repair is performed by a surgical procedure as necessary at an insertion site.

As described above, the stylet50according to this embodiment is the stylet50formed to be insertable into the catheter30provided with the expandable expansion portion32, the shaft portion33provided at the proximal end of the expansion portion32, and the lumen30A through which the blood may flow, the stylet50capable of extending the expansion portion32in the axial direction. The stylet50includes the outer peripheral member51that extends in the axial direction and has the same outer diameter as the inner diameter of the shaft portion33, the inner peripheral member52provided with the exposed portion52A exposed from the distal end of the outer peripheral member51and is provided on the inner periphery of the outer peripheral member51so as to be slidable with respect to the outer peripheral member51, the fitted portion54A into which the fitting member53joined to the outer periphery of the proximal end of the outer peripheral member51is fittable, and the fitting stopper54in which the region54D in which the outer peripheral member51and the fitting member53may move is formed. According to the stylet50formed in this manner, when the stylet50is inserted into the catheter30, the shaft portion33is about to contract radially inward, but the shaft portion33comes into contact with the outer peripheral member51, the contraction of the shaft portion33radially inward is regulated, and the outer peripheral member51does not move in the axial direction due to friction. In this state, by moving the inner peripheral member52toward the distal end side with respect to the outer peripheral member51, the expansion portion32of the catheter30extends in the axial direction and suitably contracts radially inward. As a result of the above actions, at the time of insertion into the catheter30, the expansion portion32may be suitably contracted radially inward.

Next, a variation of the catheter is described. In the embodiment described above, the stylet50is applied to the catheter30provided with one lumen30A. However, this may also be used for a catheter60provided with a double lumen as illustrated inFIGS.8to10. Hereinafter, a configuration of the catheter60provided with the double lumen is described with reference toFIGS.8to10.

The catheter60is a so-called double lumen catheter, and may simultaneously perform both blood supply and blood removal. Therefore, in this embodiment, a procedure is performed using only one catheter60without using two catheters of a vein-side catheter (blood removal catheter)5and an artery-side catheter (blood supply catheter)6in the extracorporeal circulation device inFIG.1.

As illustrated inFIGS.8and9, the catheter60has a double tube structure in which a third tube161provided with a first lumen61communicating with a blood supply side hole163is arranged in an inner cavity of a shaft portion133.

According to the catheter60, it is possible to perform veno-venous (VV) oxygenator extracorporeal blood circulation of removing blood from a vein (vena cava) of a patient by operating a pump of the extracorporeal circulation device, exchanging gas in the blood by an oxygenator to oxygenate the blood, and then returning the blood to an artery (aorta) of the patient again.

As illustrated inFIGS.8to10, the catheter60includes an expansion portion32, a shaft portion133, a distal end tip41arranged at a distal end of the expansion portion32, and the third tube161arranged in an inner cavity of the shaft portion133. Since configurations of the expansion portion32and the distal end tip41are the same as those of the catheter30of the first embodiment, the description thereof is omitted.

As illustrated inFIG.9, the catheter60includes a first lumen61serving as a blood supply path and a second lumen62serving as a blood removal path.

The first lumen61is formed in an inner cavity of the third tube161. The second lumen62is formed in the inner cavity of the expansion portion32and the shaft portion133, and penetrates from a distal end to a proximal end.

The shaft portion133is provided with the blood supply side hole163communicating with the first lumen61, which is the blood supply path.

The shaft portion133is provided with a blood removal side hole164communicating with the second lumen62, which is the blood removal path.

Each of the blood supply side hole163and the blood removal side hole164is formed into an elliptical shape.

The third tube161is inserted into the second lumen62from a proximal end side of the shaft portion133and connected to the blood supply side hole163.

The blood supply side hole163is arranged in a blood supply target in a living body, and the blood oxygenated by the oxygenator is delivered into the living body via the blood supply side hole163.

A through-hole47provided on the distal end tip41, a second side hole46provided on the expansion portion32, and the blood removal side hole164provided on the shaft portion133are arranged in different blood removal targets in the living body such that the blood may be efficiently removed. Even if the through-hole47, the second side hole46, or the blood removal side hole164is adsorbed to a blood vessel wall and blocked, the blood removal may be performed by the hole that is not blocked, so that extracorporeal circulation may be stably performed.

In this embodiment, the catheter60is inserted from the internal jugular vein of the neck, and a distal end thereof is indwelled in the inferior vena cava via the superior vena cava and the right atrium. The blood supply target is the right atrium and the blood removal target is two sites: the superior vena cava and the inferior vena cava.

The catheter60is inserted into the living body to be indwelled there such that the through-hole47of the distal end tip41and the second side hole46of the expansion portion32are arranged in the inferior vena cava, and the blood removal side hole164of the shaft portion133is arranged in the internal jugular vein in a state in which the stylet50is inserted as illustrated inFIG.12.

The expansion portion32is formed to have a larger inner diameter than that of the shaft portion133. In a state in which the through-hole47, the second side hole46, and the blood removal side hole164are arranged in the blood removal targets, the expansion portion32is arranged in the inferior vena cava, which is a relatively large blood vessel, and the shaft portion133is arranged in the femoral vein, which is a relatively small blood vessel.

As illustrated inFIG.9, a lock connector136includes a first lock connector137communicating with the first lumen61and a second lock connector138provided in parallel with the first lock connector137and communicating with the second lumen62. The lock connector136is a Y-shaped Y connector formed by branching the first lock connector137from the second lock connector138.

The first lock connector137is connected to a proximal end part of the third tube161. The second lock connector138is coaxially connected to a proximal end part of the shaft portion133. A blood supply tube (blood supply line) is connected to the first lock connector137, and a blood removal tube (blood removal line) is connected to the second lock connector138.

As described above, according to the catheter60according to this embodiment, one catheter may perform both functions of blood removal and blood supply.

Next, a configuration of a stylet150according to a variation is described with reference toFIGS.11A to11C. Description of a part common to the configuration of the stylet50according to the embodiment described above is omitted. The stylet150according to the variation is different from the stylet50according to the embodiment described above in that a regulation member155is provided on an outer periphery of an outer peripheral member51.

As illustrated inFIGS.11A to11C, the stylet150according to the variation includes the outer peripheral member51that extends in an axial direction, an inner peripheral member52provided on an inner periphery of the outer peripheral member51, a fitting member53joined to an outer periphery of a proximal end of the outer peripheral member51, a fitting stopper54into which the fitting member53may be fitted, and a regulation member155joined to the outer periphery of the outer peripheral member51spaced from a distal end side of the fitting member53. Since configurations of the outer peripheral member51, the inner peripheral member52, the fitting member53, and the fitting stopper54are the same as those of the stylet50according to the above-described embodiment, the description thereof is omitted.

The regulation member155is provided on the distal end side of the fitting member53. The regulation member155is joined to the outer periphery of the outer peripheral member51. A method of joining the regulation member155to the outer peripheral member51is not especially limited, and is, for example, adhesion using an adhesive.

An outer diameter of the regulation member155is formed to be slightly larger than an inner diameter of a male screw portion36A so as to be fitted into an inner periphery of the male screw portion36A of the lock connector36. The regulation member155is formed of an elastically deformable material, and is fitted into the inner periphery of the male screw portion36A of the lock connector36by elastic deformation of the regulation member155. Note that, the regulation member155is not especially limited as long as this may regulate motion of the outer peripheral member51in the axial direction. For example, the regulation member155may be provided at a proximal end of the male screw portion36A.

A distance from the proximal end of the regulation member155to a screw ring54C of the fitting stopper54is the same as an extension length of the remaining expansion portion32when the shaft portion33starts contracting.

<Method of Using Stylet According to Variation>

Next, a method of using the stylet150according to the variation is described with reference toFIGS.11A to11C.FIGS.11A to11Care views for describing the method of using the stylet150according to the variation.

First, as illustrated inFIG.11A, the stylet150is inserted into the lumen30A of the catheter30. The stylet150sequentially passes through the inside of the shaft portion33and the expansion portion32, until a flat surface52aof the inner peripheral member52of the stylet150abuts a receiving surface48of the distal end tip41. At that time, the regulation member155becomes fitted into the inner periphery of the male screw portion36A of the lock connector36.

Then, the distal end of the expansion portion32is pulled toward the distal end side as illustrated inFIG.11B. As a result, the catheter30receives a force to extend in the axial direction, and the expansion portion32having relatively high elasticity out of the catheter30extends in the axial direction. The motion of the outer peripheral member51in the axial direction may be regulated by the regulation member155. Therefore, in this state, by moving the inner peripheral member52toward the distal end side with respect to the outer peripheral member51, the expansion portion32of the catheter30extends in the axial direction and contracts radially inward. At that time, the fitting member53fitted into the fitted portion54A of the fitting stopper54is displaced from the fitted portion54A.

Thereafter, the stylet50is attached to the catheter30by screwing the female screw portion of the screw ring54C into the male screw portion36A provided on the lock connector36of the catheter as illustrated inFIG.11C. At that time, as illustrated inFIG.11C, proximal ends of the fitting member53and the outer peripheral member51abut a proximal end of a region54D of the fitting stopper54.

Following steps are similar to those in the method of using the stylet50according to the embodiment, so that the description thereof is omitted.

Although the catheter according to the present invention is described with the embodiment, the present invention is not limited only to the configuration described in the embodiment and variation, and may be appropriately changed based on the recitation in claims.

For example, in the above-described embodiment, the inner peripheral member52is formed of a material softer than that of the outer peripheral member51, but the inner peripheral member52may be formed of a material as soft as that of the outer peripheral member51.

The material forming the wire W is not limited to the shape memory material as long as the material has a restoring force to return to its original shape by deformation and has a function of reinforcing the resin layer; for example, the wire W may be formed of a known elastic material.

In the above-described embodiment, the outer diameter of the fitting member53is formed to be slightly larger than the inner diameter of the fitted portion54A of the fitting stopper54. However, there is no particular limitation as long as the fitting member is fittable into the fitted portion. For example, as illustrated inFIG.12, an inner periphery of a fitting member153may be fitted so as to be engaged with an outer periphery of a fitted portion154A.