Balloon catheter

A balloon catheter has a balloon and an outer shaft fixed to a proximal end of the balloon. Each of the proximal end of the balloon and a distal end of the outer shaft has an inner projection extending in an axial direction of the balloon catheter, an outer projection extending in the axial direction, and a gap formed between the inner projection and the outer projection. At a fixing part, the inner projection of the balloon or the outer projection of the balloon is disposed in the gap of the outer shaft, and the inner projection of the outer shaft or the outer projection of the outer shaft is disposed in the gap of the balloon. The balloon catheter has improved fixing strength between the balloon and the outer shaft without increasing an outer diameter of the fixing part between the balloon and the outer shaft.

BACKGROUND

The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a balloon catheter.

A balloon catheter expands a constricted portion formed in a blood vessel or a digestive organ to recover a flow of blood or a digestion liquid, and a fixing balloon catheter easily facilitates operation of inserted medical equipment such as a guide wire by expanding a balloon against a blood vessel wall or a digestive organ wall and fixing the balloon. Such balloon catheters mainly include a balloon that is an expansion body, an outer shaft fixed to a proximal end of the balloon, and an inner shaft inserted in the balloon and the outer shaft. Generally, the inner shaft is used to allow a guide wire to pass through the balloon catheter, and an expansion lumen provided between the outer shaft and the inner shaft is used to supply a liquid for expanding the balloon (e.g., contrast medium or physiological saline).

The conventional balloon catheter has a problematically low fixing strength between the proximal end of the balloon and the outer shaft, and the proximal end of the balloon can be removed from a distal end of the outer shaft when the balloon is expanded to expand a constricted portion or to fix the balloon to a blood vessel wall or a digestive organ wall.

As a method of solving this problem, the fixing strength between the balloon and the outer shaft can be improved by coating the outer periphery of the proximal end of the balloon and the distal end of the outer shaft with a heat shrinkable tube that is a separate member (see Japanese Patent Application Laid-open No. 2009-056297, for example). Alternatively, the fixing strength between the balloon and the distal end of the outer shaft can be improved by providing a mutually diagonally cut overlapped part between the proximal end of the balloon and the distal end of the outer shaft (see Japanese Patent No. 5237572, for example).

However, because the heat shrinkable tube is a separate member in the balloon catheter described in Japanese Patent Application Laid-open No. 2009-056297, an outer diameter of the fixing part between the balloon and the outer shaft is large, thereby causing a problem that the passing performance of the balloon catheter is deteriorated. Moreover, in the balloon catheter described in Japanese Patent No. 5237572, there is a limit to how much the fixing area between the balloon and the outer shaft can be increased, which means improvement of the fixing strength between the balloon and the outer shaft also has a limit. Especially when high pressure is imposed on the balloon, there is a risk that the proximal end of the balloon will separate from the distal end of the outer shaft.

SUMMARY

In view of the above-described problems, the disclosed embodiments aim to provide a balloon catheter having improved fixing strength between a balloon and an outer shaft without increasing an outer diameter of a fixing part between the balloon and the outer shaft.

The following means address the above-described problems.

A balloon catheter according to the disclosed embodiments comprises a balloon and an outer shaft fixed to a proximal end of the balloon. Each of the proximal end of the balloon and a distal end of the outer shaft has an inner projection extending in an axis direction, which is in a direction of the longitudinal axis, an outer projection extending in the axis direction, and a gap formed between the inner projection and the outer projection. The inner projection of the balloon or the outer projection of the balloon is disposed in the gap of the outer shaft, and the inner projection of the outer shaft or the outer projection of the outer shaft is disposed in the gap of the balloon. Thus, a fixing area between the balloon and the outer shaft can be easily increased. Therefore, it is possible to improve the fixing strength between the balloon and the outer shaft without increasing an outer diameter at the fixing part between the balloon and the outer shaft. Moreover, the proximal end of the balloon and the distal end of the outer shaft are engaged with each other. Thus, it is possible to reduce the risk that the proximal end of the balloon will separate from the distal end of the outer shaft even when a high pressure is imposed on the balloon.

A bulging portion may be provided at the inner projection of the balloon or the outer projection of the balloon that is disposed in the gap of the outer shaft. This can further expand the fixing area between the balloon and the outer shaft, and the anchoring effect of the bulging portion relative to the gap of the outer shaft can further improve the fixing strength between the balloon and the outer shaft.

Alternatively or additionally, a bulging portion may be provided at the inner projection of the outer shaft or the outer projection of the outer shaft that is disposed in the gap of the balloon. This can further expand the fixing area between the balloon and the outer shaft, and the anchoring effect of the bulging portion relative to the gap of the balloon can further improve the fixing strength between the balloon and the outer shaft.

DETAILED DESCRIPTION OF EMBODIMENTS

A balloon catheter1according to the disclosed embodiments will be described with reference toFIG. 1toFIG. 3. Throughout the drawings, the left side corresponds to a distal end (front end) to be inserted in a body, while the right side corresponds to a proximal end (rear end) to be operated by a technician such as a physician.FIG. 2is an enlarged view of part A shown inFIG. 1.FIGS. 3A and 3Bare diagrams illustrating, for facilitating understanding, a state where a balloon10and an outer shaft20that are illustrated inFIG. 2are separated from each other.

The balloon catheter1is, for example, a medical treatment balloon catheter used to expand a constricted portion of a vessel for treatment. As illustrated inFIG. 1, the balloon catheter1includes the balloon10, the outer shaft20, an inner shaft30, a distal end tip40, a reinforcing body50, and a connector60.

The balloon10for expanding a constricted portion is formed of a resin member, and includes a distal end attachment part11at a distal end of the balloon10, and a proximal end attachment part12at a proximal end of the balloon10. The distal end attachment part11is fixed to a distal end of the inner shaft30through the distal end tip40, and the proximal end attachment part12is fixed to a distal end21of the outer shaft20. However, the embodiment is not limited thereto. For example, the distal end attachment part11may be held between the inner shaft30and the distal end tip40so that the distal end attachment part11of the balloon10is directly fixed to the inner shaft30.

The outer shaft20is a tubular member forming an expansion lumen26for supplying liquid such as a contrast medium or physiological saline to expand the balloon10. The outer shaft20includes a distal end outer shaft part22, a guide wire port part23, an intermediate outer shaft part24, and a proximal end outer shaft part25in this order from the distal end. The distal end outer shaft part22and the intermediate outer shaft part24are tubes formed of resin of polyamide, polyamide elastomer, polyolefin, polyester, or polyester elastomer. The guide wire port part23is a part where the distal end outer shaft part22, the intermediate outer shaft part24, and the inner shaft30are fixed to one another.

The inner shaft30is inserted in the distal end outer shaft part22, and the above-described expansion lumen26is formed between the distal end outer shaft part22and the inner shaft30.

The proximal end outer shaft part25is a metallic tubular member: a so-called hypo tube. A distal end of the proximal end outer shaft part25is inserted into and fixed to a proximal end of the intermediate outer shaft part24. A connector60is attached to a proximal end of the proximal end outer shaft part25. When liquid such as a contrast medium or physiological saline for expanding the balloon10is supplied from an indeflator (not illustrated) that can be attached to the connector60, the liquid passes through the expansion lumen26and expands the balloon10. Note that the material of the proximal end outer shaft part25is not particularly limited, and stainless steel (SUS302, SUS304) or a superelastic alloy such as a Ni—Ti alloy can be used.

The inner shaft30has therein a guide wire lumen31into which a guide wire can be inserted. A proximal end of the inner shaft30is fixed to the guide wire port part23of the outer shaft20to form a proximal end guide wire port32. A technician can exchange guide wires through the proximal end guide wire port32.

As described later, the distal end tip40is fixed to a distal end of the inner shaft30. The distal end tip40is formed of flexible resin. The material is not particularly limited, and polyurethane, polyurethane elastomer, and the like can be used. Moreover, the distal end tip40has a distal end guide wire port41on its distal end.

The reinforcing body50is attached on an inner periphery of the distal end of the proximal end outer shaft part25. The reinforcing body50has a circular cross section, and is a metal wire tapered toward the distal end. The material of the reinforcing body50is not particularly limited, and stainless steel (SUS304) or a superelastic alloy such as a Ni—Ti alloy can be used. The reinforcing body50extends through the intermediate outer shaft part24and past the guide wire port part23and into to the distal end outer shaft part22.

As illustrated inFIG. 3A, there are provided, at the proximal end12of the balloon10, an outer projection70extending in an axis direction (an axial direction of the balloon catheter1), an inner projection72extending in the axis direction, and a gap71formed between the outer projection70and the inner projection72. That is, the outer projection70and the inner projection72are spaced apart from each other. As illustrated inFIG. 3B, there are provided, at the distal end21of the outer shaft20, an outer projection80extending in the axis direction, an inner projection82extending in the axis direction, and a gap81formed between the outer projection80and the inner projection82.

In the balloon catheter1, the inner projection72of the balloon10is disposed in the gap81of the outer shaft20, and the outer projection80of the outer shaft20is disposed in the gap71of the balloon10(seeFIG. 2). In other words, at a fixing part14between the proximal end12of the balloon10and the distal end21of the outer shaft20, there are sequentially laminated in a diameter direction (in a radial direction from an inside of the balloon catheter1toward an outside of the balloon catheter1) the inner projection82of the outer shaft20, the inner projection72of the balloon10, the outer projection80of the outer shaft20, and the outer projection70of the balloon10.

In this manner, the proximal end12of the balloon10and the distal end21of the outer shaft20are engaged with each other, whereby a fixing area (the contact area at the fixing part14) between the balloon10and the outer shaft20can be easily increased. Thus, it is possible to improve the fixing strength between the balloon10and the outer shaft20without increasing an outer diameter at the fixing part14between the balloon10and the outer shaft20. As a result, it is possible to reduce the risk that the proximal end12of the balloon12will separate from the distal end21of the outer shaft20even when a technician imposes high pressure on the balloon10.

Next, a balloon catheter2of the disclosed embodiments will be described with reference toFIG. 4. Explaining only a difference from the balloon catheter1, in the balloon catheter2, the outer projection70of the balloon10is disposed in the gap81of the outer shaft20, and the inner projection82of the outer shaft20is disposed in the gap71of the balloon10(seeFIG. 4). In other words, at a fixing part14abetween the proximal end12of the balloon10and the distal end21of the outer shaft20, there are sequentially laminated in the diameter direction the inner projection72of the balloon10, the inner projection82of the outer shaft20, the outer projection70of the balloon10, and the outer projection80of the outer shaft20.

The fixing part14aof the balloon catheter2has a structure in which the proximal end12of the balloon10and the distal end21of the outer shaft20are engaged with each other, similarly to the fixing part14of the balloon catheter1. Thus, a fixing area between the balloon10and the outer shaft20can be easily increased. Thus, it is possible to improve the fixing strength between the balloon10and the outer shaft20without increasing an outer diameter at the fixing part14abetween the balloon10and the outer shaft20. As a result, it is possible to reduce the risk that the proximal end12of the balloon10will separate from the distal end21of the outer shaft20even when a technician imposes a high pressure on the balloon10.

Next, balloon catheters3A,3B of the disclosed embodiments will be described with reference toFIG. 5AandFIG. 5B. Explaining only a difference from the balloon catheter1, in the balloon catheter3A, a bulging portion74is provided at a proximal end of the inner projection72of a balloon10adisposed in a gap81aof an outer shaft20a,as illustrated inFIG. 5A. The bulging portion74is formed of the same material as the inner projection72, and has a greater thickness in the diameter direction than the inner projection72. In other words, a thickness X1of the bulging portion74is larger than a thickness X2of the inner projection72(X1>X2).

Similarly, explaining only a difference from the balloon catheter2, in the balloon catheter3B, a bulging portion74ais provided at a proximal end of the outer projection70of a balloon10bdisposed in the gap81aof the outer shaft20a,as illustrated inFIG. 5B. The bulging portion74ais formed of the same material as the outer projection70, and has a greater thickness in the diameter direction than the outer projection70. In other words, a thickness X3of the bulging portion74ais larger than a thickness X4of the outer projection70(X3>X4).

In this manner, the bulging portion74,74aprovided at the proximal end of the inner projection72or the outer projection70is disposed in the gap81aof the outer shaft20a,whereby a fixing area between the balloons10a,10band the outer shaft20acan be further increased, and the anchoring effect of the bulging portion74,74arelative to the gap81aof the outer shaft20acan further improve the fixing strength between the balloon10a,10band the outer shaft20a.

Next, balloon catheters4A,4B of the disclosed embodiments will be described with reference toFIG. 6AandFIG. 6B. Explaining only a difference from the balloon catheter1, in the balloon catheter4A, a bulging portion84is provided at a distal end of the outer projection80of an outer shaft20bdisposed in a gap71aof a balloon10c,as illustrated inFIG. 6A. The bulging portion84is formed of the same material as the outer projection80, and has a greater thickness in the diameter direction than the outer projection80. In other words, a thickness X5of the bulging portion84is larger than a thickness X6of the outer projection80(X5>X6).

Similarly, explaining only a difference from the balloon catheter2, in the balloon catheter4B, a bulging portion84ais provided at a distal end of the inner projection82of an outer shaft20cdisposed in the gap71aof the balloon10c,as illustrated inFIG. 6B. The bulging portion84ais formed of the same material as the inner projection82, and is has a greater thickness in the diameter direction than the inner projection82. In other words, a thickness X7of the bulging portion84ais larger than a thickness X8of the inner projection82(X7>X8).

In this manner, the bulging portion84,84aprovided at the distal end of the outer projection80or the inner projection82is disposed in the gap71aof the balloon10c, whereby the fixing area between the balloon10cand the outer shaft20b,20ccan be further increased, and the anchoring effect of the bulging portion84,84arelative to the gap71aof the balloon10ccan further improve the fixing strength between the balloon10cand the outer shaft20b,20c.

Next, balloon catheters5A,5B of the disclosed embodiments will be described with reference toFIG. 7AandFIG. 7B. Explaining only a difference from the balloon catheter4A, in the balloon catheter5A, the bulging portion74is provided, in addition to the bulging portion84, at the proximal end of the inner projection72of a balloon10ddisposed in the gap81aof an outer shaft20d,as illustrated inFIG. 7A. Note that the bulging portion74is same as in the balloon catheter3A shown inFIG. 5A, and thus the explanation thereof is omitted.

Similarly, explaining only a difference from the balloon catheter4B, in the balloon catheter5B, the bulging portion74ais provided, in addition to the bulging portion84a,at the proximal end of the outer projection70of a balloon10edisposed in the gap81aof an outer shaft20e,as illustrated inFIG. 7B. Note that the bulging portion74ais same as in the balloon catheter3B shown inFIG. 5B, and thus the explanation thereof is omitted.

In this manner, the bulging portion84,84aprovided at the distal end of the outer projection80or the inner projection82is disposed in the gap71aof the balloon10d,10e,and the bulging portion74,74aprovided at the proximal end of the inner projection72or the outer projection70is disposed in the gap81aof the outer shaft20d,20e,whereby the fixing area between the balloon10d,10eand the outer shaft20d,20ecan be further increased. In addition, the anchoring effect of the bulging portion84,84arelative to the gap71aof the balloon10d,10e,and the anchoring effect of the bulging portion74,74arelative to the gap81aof the outer shaft20d,20ecan further improve the fixing strength between the balloon10d,l0eand the outer shaft20d,20e.

The balloon catheters3A to5B include one bulging portion74at the proximal end of the inner projection72of the balloon10a,10d(catheter3A,5A), one bulging portion74aat the proximal end of the outer projection70of the balloon10b,l0e(catheter3B,5B), one bulging portion84at the distal end of the outer projection80of the outer shaft20b,20d(catheter4A,5A), and one bulging portion84aat the distal end of the inner projection82of the outer shaft20c,20e(catheter4B,5B). The number and the position of the bulging portions74,74a,84,84aare not particularly limited. For example, in a balloon catheter6A of the disclosed embodiments illustrated inFIG. 8A, two bulging portions84,85provided at the distal end and the middle (an intermediate position) of the outer projection80of an outer shaft20fmay be disposed in a gap71bof a balloon10f,and two bulging portions74,75provided at the proximal end and the middle of the inner projection72of the balloon10fmay be disposed in a gap81bof the outer shaft20f. Moreover, in the balloon catheter6B of the disclosed embodiments illustrated inFIG. 8B, two bulging portions84a,85aprovided at the distal end and the middle of the inner projection82of the outer shaft20fmay be disposed in the gap71bof the balloon10f,and two bulging portions74a,75aprovided at the proximal end and the middle of the outer projection70of the balloon10fmay be disposed in the gap81bof the outer shaft20f.

Note that the form of the bulging portions74,74a,75,75a,84,84a,85,85ais not limited to the form illustrated inFIG. 5AtoFIG. 8Bas long as the anchoring effect can be obtained.

Instead of the above-described bulging portions74,74a,75,75a,84,84a,85,85a,an uneven inner peripheral surface76may be provided in a gap71cof a balloon10g, and an uneven inner peripheral surface86may be provided in a gap81cof an outer shaft20g, as illustrated in a balloon catheter7shown inFIGS. 9A, 9B.

To be more specific, there are provided, at the proximal end12of the balloon10g,an outer projection70aextending in the axis direction, an inner projection72aextending in the axis direction, and the gap71cthat is formed between the outer projection70aand the inner projection72aand that has the uneven inner peripheral surface76, as illustrated inFIG. 9A. Moreover, as illustrated inFIG. 9B, there are provided, at the distal end21of the outer shaft20g,an outer projection80aextending in the axis direction, an inner projection82aextending in the axis direction, and the gap81cthat is formed between the outer projection80aand the inner projection82aand that has the uneven inner peripheral surface86. Similarly toFIGS. 3A, 3B,FIGS. 9A, 9Billustrate, for facilitating understanding, the state where the balloon10gand the outer shaft20gare separated from each other.

In such a manner, the inner peripheral surface76is provided in the gap71cof the balloon10g,and the inner peripheral surface86is provided in the gap81cof the outer shaft20g.Then, the inner peripheral surface76and the inner peripheral surface86are fixed to each other, whereby the fixing area between the balloon10gand the outer shaft20gcan be increased. As a result, it is possible to improve the fixing strength between the balloon10gand the outer shaft20g.

Next, a balloon catheter8of the disclosed embodiments will be described with reference toFIG. 10. In the balloon catheter8, the same symbols as in the balloon catheters1to7described above represent the same members unless otherwise specified.

The balloon catheter8is, for example, a fixing balloon catheter that facilitates insertion of medical equipment such as a guide wire by expanding a balloon against a blood vessel wall or a digestive organ wall and fixing the balloon. As illustrated inFIG. 10, the balloon catheter8includes the balloon10, the outer shaft20, a first inner shaft34, a second inner shaft33, the reinforcing body50, and a connector62.

In the outer shaft20, the second inner shaft33extends throughout the whole length of the balloon catheter8. A guide wire can be inserted into the second inner shaft33. In order to facilitate insertion of the guide wire, the connector62is connected to the proximal end of the outer shaft20and a proximal end of the second inner shaft33. A first distal end port33ais provided at a distal end of the second inner shaft33, and a first insertion port64is provided at the proximal end of the second inner shaft33through the connector62.

In the outer shaft20, the first inner shaft34extends, in parallel to the second inner shaft33, from the middle to a distal end of the balloon catheter8. Similarly to the second inner shaft33, the guide wire can be inserted into the first inner shaft34. A second distal end port34ais provided at a distal end of the first inner shaft34, and a second insertion port34bis provided at a proximal end of the first inner shaft34.

The outer shaft20, the first inner shaft34, and the second inner shaft33are formed of thermoplastic resin. For example, polyamide, polyamide elastomer, polyolefin, polyester, polyester elastomer, or nylon can be used.

The second inner shaft33extends over the whole length of the balloon catheter8. Thus, it can be difficult for the technician to change the guide wire inserted in the second inner shaft33because the second inner shaft33is long. However, the guide wire inserted in the second inner shaft33improves rigidity of the balloon catheter8, and thus the technician can easily push the balloon catheter8in the distal direction.

Moreover, the first inner shaft34extends only from the middle to the distal end of the balloon catheter8. Thus, the technician can easily change the guide wire inserted in the first inner shaft34. However, the rigidity of the balloon catheter8is improved only from the middle to the distal end of the balloon catheter8where the guide wire is inserted, and the balloon catheter8can break around the second insertion port34bof the first inner shaft34where the rigidity changes suddenly when the technician pushes the balloon catheter8in the distal direction.

By including both the first inner shaft34and the second inner shaft33, the technician can rapidly change a second guide wire inserted in the first inner shaft34while a first guide wire is inserted in the second inner shaft33, and the balloon catheter8can be easily pushed in the distal direction.

As illustrated inFIG. 10, the balloon10fixed to a blood vessel wall or a digestive organ wall is formed of a resin member, and includes the distal end attachment part11at the distal end of the balloon10, and the proximal end attachment part12at the proximal end of the balloon10. The distal end attachment part11is fixed to the first inner shaft34and the second inner shaft33, while the proximal end attachment part12is fixed to the distal end21of the outer shaft20.

In order to expand the balloon10, an expansion lumen for supplying liquid such as a contrast medium or physiological saline is provided between the outer shaft20, and the first inner shaft34and the second inner shaft33, although it is not illustrated. A liquid supply port66to which an indeflator (not illustrated) can be attached is provided in the connector62. The liquid such as a contrast medium or physiological saline supplied from the liquid supply port66passes through the expansion lumen to the balloon10, then expanding the balloon10.

In the balloon catheter8, the metal reinforcing body50extending in an axis direction is inserted between the outer shaft20and the second inner shaft33. The distal end of the reinforcing body50extends past the second insertion port34bof the first inner shaft34in the distal direction.

Similarly to the balloon catheters1to7, in the balloon catheter8, the proximal end12of the balloon10and the distal end21of the outer shaft20are engaged with each other, whereby a fixing area between the balloon10and the outer shaft20can be easily increased. Thus, it is possible to improve the fixing strength between the balloon10and the outer shaft20without increasing an outer diameter at the fixing part14between the balloon10and the outer shaft20. As a result, even when a technician imposes a high pressure on the balloon10, it is possible to reduce the risk that the proximal end12of the balloon10will separate from the distal end21of the outer shaft20.