JP7527219B2 - Balloon catheter - Google Patents

Description

The present invention relates to a balloon catheter.

When a balloon catheter is used to expand a stenosis in a blood vessel, the expansion capacity depends on the diameter of the balloon in the expanded state (hereinafter referred to as the "expansion diameter"). For this reason, it is necessary to select and use a balloon catheter containing a balloon with an appropriate expansion diameter according to the type and size of the stenosis in the blood vessel. However, since the inner diameter of the stenosis is often not constant along the longitudinal direction, and multiple stenosis with different inner diameters often exist at the same time, the appropriate expansion diameter of the balloon used in one treatment may not be constant. In this case, even when a single treatment is performed, it is necessary to use multiple balloon catheters with different balloon expansion diameters. In this case, the treatment time may be longer, which may increase the burden on the patient, medical staff, practitioner, etc.

US Patent No. 5,999,336 discloses an angioplasty balloon having selectively deployable cutting or scoring elements (hereinafter simply referred to as "elements"). In the angioplasty balloon, the elements are wound in a spiral shape around the balloon. In the angioplasty balloon, the balloon can be switched between a fully inflated state and a partially inflated state by adjusting the degree of tension of a tensioning member connected to the elements. This allows the expansion diameter of the balloon to be changed during the procedure, eliminating the need for multiple balloon catheters.

Special table 2016-520369 publication

However, with the above angioplasty balloon, it is necessary to adjust the degree of tension of the tensioning member so that the balloon has an appropriate expansion diameter. This poses the problem that even experienced users often have difficulty in operating the balloon to the desired expansion diameter.

The object of the present invention is to provide a balloon catheter whose balloon can be easily adjusted to have a number of different expansion diameters.

The balloon catheter according to the present invention is characterized by comprising a balloon that can expand and contract between an expanded state and a contracted state, and a diameter control member for controlling the expansion diameter of the balloon in the expanded state, the diameter control member having a plurality of control elements fixed at different positions on the balloon in the circumferential direction, the plurality of control elements being switched between a separated state in which each of the plurality of control elements is separated from each other in the circumferential direction, and a close state in which the distance between at least two of one or more sets of control elements is smaller than the separated state, depending on a change in an external force acting between the at least two control elements, the balloon being in a maximum diameter state in which the expansion diameter is a maximum diameter in the separated state, and the balloon being in an intermediate diameter state in which the expansion diameter is an intermediate diameter smaller than the maximum diameter in the close state.

The balloon catheter controls the expansion diameter of the balloon using a diameter control member. The diameter control member sets the expansion diameter of the balloon to a maximum diameter when the multiple control elements are in a separated state, and sets the expansion diameter of the balloon to an intermediate diameter when the multiple control elements are in a close state. Here, the diameter control member switches the multiple control elements between a separated state and a close state depending on the external force acting on each of them. Therefore, the user can switch the expansion diameter of the balloon by adjusting the external force acting on the multiple control elements. Therefore, the user can easily adjust the balloon to have multiple different expansion diameters.

In the present invention, the plurality of control elements may include four or more control elements, and in the close state, the distance between two or more sets of two control elements may be smaller than in the separated state. In this case, the balloon catheter can stabilize the close state of the plurality of control elements, and therefore can stably maintain the balloon in the intermediate diameter state.

In the present invention, the multiple control elements may be arranged at equal intervals in the circumferential direction in the separated state. In this case, the cross-sectional shape of the balloon in the intermediate diameter state of the balloon catheter can be made closer to a circle, so that the stenosis can be uniformly expanded in the circumferential direction of the balloon.

In the present invention, the at least two control elements may contact each other in the close state. In this case, the balloon catheter can appropriately apply an attractive force between the multiple control elements, so that the multiple control elements can be reliably switched between a separated state and a close state, and the expansion diameter of the balloon can be appropriately adjusted.

In the present invention, the external force may be the expansion force of the balloon, and the diameter control member may control the expansion diameter of the balloon by frictional force. In this case, the balloon catheter can stably maintain multiple control elements in a close proximity state.

In the present invention, the at least two control elements may include at least a first control element including a recess and a second control element having a protrusion that can fit into the recess. In this case, the balloon catheter can efficiently apply frictional force between the at least two control elements.

In the present invention, the external force may be an external magnetic field, and the diameter control member may control the expansion diameter of the balloon by magnetic force. In this case, the balloon catheter can use magnetic force to switch multiple control elements between a separated state and a close state.

In the present invention, the multiple control elements may be formed from a magnetic material. In this case, the balloon catheter can realize a diameter control member made of a magnetic material that can switch the multiple control elements between a separated state and a close state using magnetic force.

In the present invention, the external force may be the passage of electricity through the multiple control elements, and the diameter control member may control the expansion diameter of the balloon using electrostatic force. In this case, the balloon catheter can use electrostatic force to switch the multiple control elements between a separated state and a close state.

In the present invention, the multiple control elements may be formed of a conductor or a charged body. In this case, the balloon catheter can realize a diameter control member that can switch the multiple control elements between a separated state and a close state using electrostatic force, by using a conductor or a charged body.

In the present invention, the multiple control elements may have a cylindrical shape partially cut away by a plane extending parallel to the axis, and in a cross section perpendicular to the axis, the angle between two straight lines extending from the axis toward both ends of the chord corresponding to the plane may be within a range of 90° to 180°. In this case, the balloon catheter can exert a strong attractive force between the two control elements. Therefore, the balloon catheter can stably maintain the multiple control elements in close proximity.

In the present invention, a drug may be applied to at least a portion of the balloon. The balloon catheter can apply the drug applied to the balloon to the stenosis, thereby treating the stenosis.

In the present invention, the balloon has a first exposed portion that is exposed in the intermediate diameter state and a second exposed portion that is not exposed in the intermediate diameter state and is exposed in the maximum diameter state, and different drugs may be applied to the first exposed portion and the second exposed portion. The balloon catheter can apply different drugs to the stenosis by switching the balloon between the intermediate diameter state and the maximum diameter state.

In the present invention, the multiple control elements may be harder than the balloon. The balloon catheter can achieve the function of, for example, incising a stenotic area by using the multiple control elements.

In the present invention, the multiple control elements may be harder than the balloon, and the same drug as that applied to the balloon may be applied to the multiple control elements. When a stenosis is incised using the multiple control elements, the balloon catheter can apply the same drug as that applied to the balloon to the incision site.

In the present invention, the multiple control elements may be harder than the balloon, and a drug different from the drug applied to the balloon may be applied to the multiple control elements. When a stenosis is incised using the multiple control elements, for example, the balloon catheter can apply a drug different from the drug applied to the balloon to the incision site.

FIG. 2 is a diagram showing a balloon catheter 1A in a state where the balloon 3 is in a deflated state. FIG. 2 is a diagram showing a balloon catheter 1A in which the balloon 3 is in an intermediate diameter state. 1A is a diagram showing a balloon catheter 1A when the balloon 3 is in a maximum diameter state. FIG. 1A to 1C are diagrams for explaining a mode of use of the balloon catheter 1A. 1A to 1C are diagrams for explaining a mode of use of the balloon catheter 1A. 1A to 1C are diagrams for explaining a balloon catheter 1A in a first modified example. 13A and 13B are diagrams for explaining a plurality of control elements 6D in a second modified example and a plurality of control elements 6E and 6F in a third modified example. 13A and 13B are diagrams for explaining balloon catheters 1B and 1C in a fourth modified example.

<Overview of Balloon Catheter 1A>
An embodiment of a balloon catheter 1A according to the present invention will be described with reference to the drawings. The drawings are used to explain the technical features that the present invention can employ, and the configuration of the device described is not intended to be limiting, but is merely an illustrative example.

The balloon catheter 1A is used to dilate stenotic lesions (hereinafter referred to as "stenotic lesions") formed in vascular vessels such as blood vessels, vas deferens, fallopian tubes, and lymphatic vessels, and to reperfuse the vessels. Here, if the inner diameter of the stenotic lesion is not constant along the longitudinal direction, or if multiple stenotic lesions with different lumen diameters exist simultaneously, the appropriate balloon diameter (hereinafter referred to as "expansion diameter") required to dilate the stenotic lesion may not be constant.

In contrast, the balloon catheter 1A has a catheter shaft 2, a balloon 3, and a diameter control member 6 (see Figures 1 to 3), which will be described later. The balloon catheter 1A can be expanded to a number of different expansion diameters by using the diameter control member 6. Therefore, by controlling the balloon 3 to have an appropriate expansion diameter according to the stenotic lesion, it is possible to perform treatment using a common balloon catheter 1A.

As shown in Figs. 1 to 3, the balloon 3 is connected to one end of the catheter shaft 2. The diameter control member 6 is provided on the balloon 3. The balloon catheter 1A is used with a hub (not shown) connected to the other end of the catheter shaft 2. The hub can supply compressed fluid to the balloon 3 via the catheter shaft 2. Hereinafter, one of the two ends of the catheter shaft 2 is referred to as the "tip". The other of the two ends of the catheter shaft 2 is referred to as the "base end". The direction extending along the catheter shaft 2 is referred to as the "extension direction". On a plane perpendicular to the extension direction, in the radial direction based on the cross-sectional center of the catheter shaft 2, the side close to the cross-sectional center of the catheter shaft 2 is referred to as the "inner side", and the side away from the cross-sectional center of the catheter shaft 2 is referred to as the "outer side".

<Catheter shaft 2>
The catheter shaft 2 has an outer tube 21 and an inner tube 22. The outer tube 21 and the inner tube 22 are each a flexible tubular member. The inner diameter of the outer tube 21 is larger than the outer diameter of the inner tube 22. The inner tube 22 is disposed in the lumen of the outer tube 21, except for a predetermined portion on the tip side. The predetermined portion on the tip side of the inner tube 22 protrudes toward the tip side from the tip side end of the outer tube 21 (hereinafter referred to as the "tip 211") toward the tip side. The tip side end of the inner tube 22 (hereinafter referred to as the "tip 221") is disposed on the tip side of the tip 211 of the outer tube 21. Hereinafter, the predetermined portion on the tip side of the inner tube 22 is referred to as the "protruding portion 225". The material of the outer tube 21 and the inner tube 22 is not particularly limited, but a polyamide resin is used as an example.

Compressed fluid supplied from the hub flows through the space in the lumen of the outer tube 21 other than the lumen of the inner tube 22. The balloon 3 expands in response to the supply of compressed fluid. A guide wire (not shown) is inserted into the lumen of the inner tube 22.

<Balloon 3>
The balloon 3 can be expanded and contracted between a contracted state (see FIG. 1) and an expanded state (see FIG. 2 and FIG. 3). The contracted state indicates the state of the balloon 3 when no compressed fluid is supplied. The expanded state indicates the state of the balloon 3 when compressed fluid is supplied. One end of the balloon 3 in the stretching direction (hereinafter referred to as the "tip 3D") is connected to the vicinity of the tip 221 of the protruding portion 225 of the inner tube 22 by thermal welding. The other end of the balloon 3 in the stretching direction (hereinafter referred to as the "base end 3P") is connected to the vicinity of the tip 211 of the outer tube 21 by thermal welding. The balloon 3 covers the protruding portion 225 of the inner tube 22 from the outside. The material of the balloon 3 is not particularly limited, but a polyamide resin is used as an example.

As shown in FIG. 1, the balloon 3 is a three-blade balloon in which three blades (blade 31, 32, 33) are formed in the deflated state. Each of the blades 31, 32, 33 is folded and wrapped around the protruding portion 225 of the inner tube 22. The blades 31, 32, 33 are also called "flaps" or "wings." The diameter of the balloon 3 in the deflated state is called the "minimum diameter Rmin." Note that the diameter control member 6 (see FIG. 2 and FIG. 3), which will be described later, is omitted in FIG. 1.

2 and 3, the diameter of the balloon 3 in the expanded state is larger than the minimum diameter Rmin, which is the diameter of the balloon 3 in the contracted state. The distal cone region 3A, the expansion region 3B, and the proximal cone region 3C of the balloon 3 are defined below. The distal cone region 3A is a region in the balloon 3 in the expanded state that extends from the distal end 3D to the proximal end 3P while expanding in diameter. The proximal cone region 3C is a region in the balloon 3 in the expanded state that extends from the proximal end 3P to the distal end 3D while expanding in diameter. The expansion region 3B is a region sandwiched between the distal cone region 3A and the proximal cone region 3C in the balloon 3 in the expanded state, and has a substantially constant diameter in the stretching direction. The side of the expansion region 3B of the balloon 3 is called the "side surface 30". The details will be described later, but the expansion diameter of the balloon 3 in the expanded state is controlled in multiple stages by the diameter control member 6 described later (see FIGS. 2 and 3).

A drug is applied to the side surface 30 of the balloon 3. There is no particular limitation on the type of drug, but for example, a well-known drug that can be attached to a stenotic lesion to perform treatment can be used.

<Diameter control member 6>
The diameter control member 6 shown in Fig. 2 and Fig. 3 controls the expansion diameter of the balloon 3 in the expanded state. The diameter control member 6 has control elements 61A, 61B, 62A, 62B, 63A, and 63B (hereinafter, also collectively referred to as "multiple control elements 6C"). Each of the multiple control elements 6C has a columnar shape and extends in the extension direction along the outer circumferential surface of the balloon 3. The multiple control elements 6C are arranged and fixed in the expansion region 3B of the balloon 3. The length of each of the multiple control elements 6C in the extension direction is approximately equal to the length of the expansion region 3B of the balloon 3 in the extension direction. As the material of each of the multiple control elements 6C, various materials described later can be used, but a material that is at least harder than the balloon 3 is used. Hereinafter, the control elements 61A and 61B are also collectively referred to as "a pair of control elements 61". The control elements 62A and 62B are also collectively referred to as "a pair of control elements 62". The control elements 63A and 63B are also collectively referred to as a "pair of control elements 63." The pair of control elements 61, 62, and 63 are collectively referred to as a "pair of control elements 60." The control elements 61A, 62A, and 63A are collectively referred to as a "control element 60A," and the control elements 61B, 62B, and 63B are collectively referred to as a "control element 60B."

In the diameter control member 6, the control elements 60A and 60B switch between a state in which they are in contact with each other and a state in which they are separated in response to an external force (such as an external magnetic field or current flow through an external conductor (not shown)) described below. More specifically, when an external force is applied, an attractive force acts between the control elements 60A and 60B. This attractive force causes the control elements 60A and 60B to be in contact with each other. This state is maintained even when compressed fluid is supplied to the balloon 3. On the other hand, when no external force is applied, the attractive force between the control elements 60A and 60B is eliminated. In this case, the control elements 60A and 60B are separated from each other in response to the supply of compressed fluid to the balloon 3.

As shown in FIG. 2, the state of the multiple control elements 6C in which the respective control elements 60A and 60B of a pair of control elements 61, 62, and 63 are in contact with each other is called the "close state." The expansion diameter of the balloon 3 in which the multiple control elements 6C are in the close state is called the "intermediate diameter Rmid." The expansion state of the balloon 3 in which the multiple control elements 6C are in the close state is called the "intermediate diameter state."

In the balloon 3 in the intermediate diameter state, the tip of wing 31 is adjacent to a part of wing 32 on the side surface 30. The tip of wing 32 is adjacent to a part of wing 33 on the side surface 30. The tip of wing 33 is adjacent to a part of wing 31 on the side surface 30. Control element 61A is arranged at the tip of wing 31. Control element 61B is arranged on a part of wing 32 on the side surface 30 of the balloon 3 that is adjacent to the tip of wing 31. Control elements 61A and 61B are in contact. Control element 62A is arranged at the tip of wing 32. Control element 62B is arranged on a part of wing 33 on the side surface 30 of the balloon 3 that is adjacent to the tip of wing 32. Control elements 62A and 62B are in contact. Control element 63A is arranged at the tip of wing 33. Control element 63B is arranged on a part of wing 31 on the side surface 30 of the balloon 3 that is adjacent to the tip of wing 33. Control elements 63A and 63B are in contact with each other. Note that the locations where control elements 61A, 62A, and 63A are placed are not limited to the tips of wings 31, 32, and 33, and they may be placed at any other location (for example, the midsection of wings 31, 32, and 33).

The portion of the side surface 30 of the balloon 3 that is exposed even in the intermediate diameter state is referred to as the "first exposed portion 30A." Additionally, the portion of the side surface 30 of the balloon 3 that is not exposed in the intermediate diameter state because it is covered by the wings 31, 32, and 33 is referred to as the "second exposed portion 30B." Different medicines are applied to the first exposed portion 30A and the second exposed portion 30B. Hereinafter, the medicine applied to the first exposed portion 30A is referred to as the "first medicine." The medicine applied to the second exposed portion 30B is referred to as the "second medicine."

Of the side surface 30 of the balloon 3 in the intermediate diameter state, the portion between the control elements 61A and 63B in the circumferential direction corresponds to the first exposed portion 31A that is exposed even in the contracted state, and the portion between the control elements 61A and 61B in the circumferential direction corresponds to the second exposed portion 31B that is not exposed in the contracted state. Of the side surface 30 of the balloon 3 in the intermediate diameter state, the portion between the control elements 62A and 61B in the circumferential direction corresponds to the first exposed portion 32A that is exposed even in the contracted state, and the portion between the control elements 62A and 62B in the circumferential direction corresponds to the second exposed portion 32B that is not exposed in the contracted state. Of the side surface 30 of the balloon 3 in the intermediate diameter state, the portion between the control elements 63A and 62B in the circumferential direction corresponds to the first exposed portion 33A that is exposed even in the contracted state, and the portion between the control elements 63A and 63B in the circumferential direction corresponds to the second exposed portion 33B that is not exposed in the contracted state.

On the other hand, as shown in FIG. 3, the state of the multiple control elements 6C that are all separated from each other in the expanded balloon 3 is called the "separated state". The expansion diameter of the balloon 3 when the multiple control elements 6C are in the separated state is called the "maximum diameter Rmax". The expansion state of the balloon 3 when the multiple control elements 6C are in the separated state is called the "maximum diameter state". When the balloon 3 is in the maximum diameter state, the positions at which each of the multiple control elements 6C is fixed differ in the circumferential direction of the balloon 3. Each of the multiple control elements 6C is disposed at equal intervals in the circumferential direction of the balloon 3. The control elements 61A, 61B, 62A, 62B, 63A, and 63B are arranged in this order in the circumferential direction. Each of the multiple control elements 6C is separated from each other in the circumferential direction. The wings 31 to 33 of the balloon 3 are eliminated when the balloon 3 is in the maximum diameter state. In this case, not only the first exposed portion 30A of the balloon 3 but also the second exposed portion 30B is exposed.

The control elements 6C are coated with a drug. The type of drug is not particularly limited, but for example, a well-known drug that can be attached to a stenotic lesion to perform treatment can be used. The drug may be the same as the drug (first drug or second drug) applied to the side surface 30 of the balloon 3, or it may be a different drug.

<External forces>
The attractive force acting between the control elements 60A and 60B is not particularly limited, but as an example, a magnetic force or an electrostatic force is preferably used.

When magnetic force is used as the attractive force, the multiple control elements 6C are formed from magnetized magnetic bodies. The material of the magnetic bodies is not particularly limited, but preferably electromagnetic stainless steel, silicon iron, neodymium magnets, etc. are used. In addition, an external magnetic field is used as an external force for switching the control elements 60A, 60B between a state in which they are in contact with each other and a state in which they are separated from each other.

For example, when an external magnetic field acts on multiple control elements 6C, a magnetic force acts as an attractive force between all of the control elements 60A, 60B. In this case, the magnetic force acts in a direction that causes the control elements 61A, 61B, the control elements 62A, 62B, and the control elements 63A, 63B to approach each other, so when compressed fluid is supplied to the balloon 3 and the balloon 3 is in an inflated state, the expanded diameter of the balloon 3 becomes an intermediate diameter Rmid that is larger than the minimum diameter Rmin in the contracted state and smaller than the maximum diameter Rmax in the maximum diameter state, as shown in FIG. 2.

On the other hand, for example, when no external magnetic field acts on the multiple control elements 6C, the magnetic force between all of the control elements 60A, 60B is ineffective. No magnetic force acts between the control elements 60A, 60B. When compressed fluid is supplied to the balloon 3 and it is in an inflated state, all of the control elements 60A, 60B are separated from each other. As a result, as shown in FIG. 3, the expanded diameter of the balloon 3 becomes a maximum diameter Rmax that is larger than the minimum diameter Rmin in the contracted state and the intermediate diameter Rmid in the intermediate diameter state. Therefore, by controlling the magnitude of the external magnetic field acting on the multiple control elements 6C, it is possible to switch the balloon 3 in the inflated state between the intermediate diameter state and the maximum diameter state.

When electrostatic force is used as the attractive force, the multiple control elements 6C are formed of a charged conductor or charged body. The material of the conductor or charged body is not particularly limited, but copper, aluminum, silver, etc. are preferably used. Furthermore, by switching the current flow state of the multiple control elements 6C, the control elements 60A, 60B are switched between a state in which they are in contact with each other and a state in which they are separated. In other words, the current flowing through the multiple control elements 6C is used as an external force for switching the control elements 60A, 60B between a state in which they are in contact with each other and a state in which they are separated.

For example, when a current is applied to the multiple control elements 6C via external conductors (not shown), an electrostatic force acts as an attractive force between all of the control elements 60A, 60B. In this case, the electrostatic force acts in a direction that causes the control elements 61A, 61B, the control elements 62A, 62B, and the control elements 63A, 63B to approach each other. Therefore, when compressed fluid is supplied to the balloon 3 and the balloon 3 is in an inflated state, the expanded diameter of the balloon 3 becomes an intermediate diameter Rmid that is larger than the minimum diameter Rmin in the contracted state and smaller than the maximum diameter Rmax in the maximum diameter state, as shown in FIG. 2.

On the other hand, for example, when the current flow to the multiple control elements 6C is stopped, the electrostatic forces between the control elements 61A and 61B, between the control elements 62A and 62B, and between the control elements 63A and 63B are all ineffective. The electrostatic force no longer acts between the control elements 60A and 60B. When compressed fluid is supplied to the balloon 3 and the balloon 3 is in an expanded state, all the control elements 60A and 60B are separated from each other. As a result, as shown in FIG. 3, the expanded diameter of the balloon 3 becomes a maximum diameter Rmax that is larger than the minimum diameter Rmin in the contracted state and the intermediate diameter Rmid in the intermediate diameter state. Therefore, by controlling the magnitude of the current flowing through the multiple control elements 6C, it is possible to switch the balloon 3 between the intermediate diameter state and the maximum diameter state.

As described above, the multiple control elements 6C control the expansion diameter of the balloon 3 in the expanded state by switching between a state in which the control elements 60A and 60B are in contact with each other and a state in which they are separated in response to an external force.

<Usage example>
4 and 5, an example of use of the balloon catheter 1A will be described. The example shows a case where the balloon catheter 1A is used to dilate stenotic lesions 90A and 90B that have occurred in parts of the inner wall of a blood vessel 9. The inner diameter of the lumen of the stenotic lesion 90A is larger than the inner diameter of the lumen of the stenotic lesion 90B.

A guidewire G is inserted into the vessel 9. As shown in FIG. 4(A), a balloon catheter 1A is prepared with the balloon 3 in a deflated state. For example, if a magnetic material is used as the multiple control elements 6C, the multiple control elements 6C are placed in a state in which no external magnetic field acts on them. Also, for example, if a conductor or charged material is used as the multiple control elements 6C, current is stopped from passing through the multiple control elements 6C. Next, a portion of the balloon catheter 1A that includes at least the balloon 3 is placed in the vessel 9. A guidewire G is inserted into the inner tube 22 of the balloon catheter 1A.

Next, the base end of the balloon catheter 1A is manipulated to push the balloon catheter 1A into the vessel 9 along the guidewire G. As shown in FIG. 4B, the balloon catheter 1A moves distally within the vessel 9 toward the stenotic lesion 90A, with the balloon 3 positioned at the front in the direction of movement. When the balloon 3 reaches the stenotic lesion 90A, the movement of the balloon catheter 1A is stopped.

Next, for example, when a magnetic material is used as the multiple control elements 6C, an external magnetic field is applied to the multiple control elements 6C. Also, for example, when a conductive or charged material is used as the multiple control elements 6C, a current is passed through the multiple control elements 6C via an external conductor. In these cases, a magnetic force or an electrostatic force acts between all the control elements 60A, 60B, and all the control elements 60A, 60B are in contact with each other due to the magnetic force or the electrostatic force. In this state, the supply of compressed fluid to the balloon 3 is started, and the balloon 3 is in an expanded state. However, since all the control elements 60A, 60B are in contact with each other, the diameter of the balloon 3 increases from the minimum diameter Rmin in the contracted state to the intermediate diameter Rmid. As a result, the balloon 3 expands the stenotic lesion 90A, as shown in FIG. 4(C).

Next, the supplied compressed fluid is removed from the balloon 3, causing the balloon 3 to contract. This causes the diameter of the balloon 3 to decrease from the intermediate diameter Rmid to the minimum diameter Rmin (see FIG. 4(D)). Furthermore, the application of external force is stopped, and no magnetic or electrostatic force acts between any of the control elements 60A and 60B.

Next, the base end of the balloon catheter 1A is manipulated, and the balloon 3 moves distally within the vessel 9 toward the stenotic lesion 90B. As shown in FIG. 5(A), when the balloon 3 reaches the stenotic lesion 90B, the movement of the balloon catheter 1A is stopped.

Next, the supply of compressed fluid to the balloon 3 begins. Unlike when the stenotic lesion 90A is expanded by the balloon 3 (see FIG. 4(C)), no external force is applied to the multiple control elements 6C. Therefore, a state in which no magnetic or electrostatic force acts between any of the control elements 60A, 60B is maintained. The expansion diameter of the balloon 3 increases from the minimum diameter Rmin to the maximum diameter Rmax. As a result, the balloon 3 expands the stenotic lesion 90B, as shown in FIG. 5(B).

Next, the compressed fluid is removed from the balloon 3. In this case, as shown in FIG. 5(C), the balloon 3 enters a contracted state, and the diameter decreases to the minimum diameter Rmin.

After the dilation of the stenotic lesions 90A, 90B is complete, the base end of the balloon catheter 1A is manipulated to move the balloon catheter 1A proximally, as shown in FIG. 5(D). The procedure is completed when the balloon catheter 1A is withdrawn from the blood vessel 9 to the outside.

<Actions and Effects of the Present Embodiment>
The balloon catheter 1A controls the expansion diameter of the balloon 3 by the diameter control member 6. The diameter control member 6 sets the expansion diameter of the balloon 3 to a maximum diameter Rmax when the control elements 6C are in a separated state. On the other hand, the diameter control member 6 sets the expansion diameter of the balloon 3 to an intermediate diameter Rmid when the control elements 6C are in a close state. Here, the diameter control member 6 switches the control elements 6C between a separated state and a close state in response to an external force acting on each of them. Therefore, the user can switch the expansion diameter of the balloon 3 by adjusting the external force acting on the control elements 6C. Therefore, the user can easily adjust the balloon 3 to have a plurality of different expansion diameters.

It is preferable to select an appropriate balloon catheter so that the balloon can be expanded to the desired expansion diameter. However, when it is difficult to specify the desired expansion diameter, for example, when a procedure is performed using a balloon with a medium expansion diameter and the expansion of the stenotic lesion is insufficient, a balloon with a large expansion diameter may be used for the procedure. The balloon catheter 1A is also effective in solving such problems, because it is possible to use a common balloon catheter 1A and switch between multiple expansion diameters for the balloon 3.

The control elements 60A, 60B come into contact with each other when in close proximity. Therefore, the balloon catheter 1A can appropriately apply an attractive force between the control elements 60A, 60B, so that the multiple control elements 6C can be reliably switched between a separated state and a close state, and the expansion diameter of the balloon 3 can be appropriately adjusted.

The diameter control member 6 has a pair of control elements 61, 62, and 63. When the multiple control elements 6C are in a close-up state, the control elements 60A and 60B come into contact with each other, as shown in FIG. 2. In this case, the balloon catheter 1A can stabilize the close-up state of the multiple control elements 6C, so that the balloon 3 can be stably maintained in an intermediate diameter state.

The multiple control elements 6C are arranged at equal intervals in the circumferential direction when in the separated state (see FIG. 3). In this case, the balloon catheter 1A can make the cross-sectional shape of the balloon 3 in the intermediate diameter state closer to a circle. Therefore, the balloon catheter 1A can uniformly expand the stenotic lesion in the circumferential direction of the balloon 3.

When an external magnetic field is used as the external force, the diameter control member 6 controls the expansion diameter of the balloon 3 by magnetic force. The multiple control elements 6C are made of a magnetic material. In this case, the balloon catheter 1A can use magnetic force to switch the multiple control elements 6C between a separated state and a close state.

When the external force is the passage of electricity through the multiple control elements 6C, the diameter control member 6 controls the expansion diameter of the balloon 3 by electrostatic force. The multiple control elements 6C are also formed of a conductor or a charged body. In this case, the balloon catheter 1A can use electrostatic force to switch the multiple control elements 6C between a separated state and a close state.

A medicinal agent is applied to the side surface 30 of the balloon 3. In this case, the balloon catheter 1A can apply the medicinal agent applied to the balloon 3 to the stenotic lesion to treat the stenotic lesion. Also, different medicinal agents are applied to the first exposed portion 30A of the side surface 30 of the balloon 3 that is exposed in the intermediate diameter state and the second exposed portion 30B that is not exposed in the intermediate diameter state and is exposed in the maximum diameter state. In this case, the balloon catheter 1A can apply different medicinal agents to the stenotic lesion by switching the balloon 3 between the intermediate diameter state and the maximum diameter state.

Since the multiple control elements 6C are harder than the balloon 3, the balloon catheter 1A can realize, for example, the function of incising a stenotic lesion by the multiple control elements 6C. Also, for example, when the same drug as that applied to the balloon 3 is applied to the multiple control elements 6C, the balloon catheter 1A can apply the same drug as that applied to the balloon 3 to the stenotic lesion incised by the multiple control elements 6C. On the other hand, for example, when the multiple control elements 6C are applied with a drug different from that applied to the balloon 3, the balloon catheter 1A can apply a drug different from that applied to the balloon 3 to the stenotic lesion incised by the multiple control elements 6C.

<First Modification>
The tendency of the attractive force to change when an external force acts on the control elements 60A, 60B may differ between the pair of control elements 61, 62, 63. In this case, for example, by adjusting the magnitude of the external force, the control elements 60A, 60B of each pair of control elements 61, 62, 63 can be individually switched between a state in which they are in contact with each other and a state in which they are separated from each other.

For example, when an external force of a predetermined first strength F1 acts on the balloon 3, the magnetic or electrostatic force no longer acts between the control elements 61A and 61B, and they may be separated from each other. On the other hand, the magnetic or electrostatic force may act as an attractive force between the control elements 62A and 62B and between the control elements 63A and 63B, and they may come into contact with each other. In this case, as shown in FIG. 6, the control elements 61A and 61B may be separated from each other and the wings 31 (see FIG. 1) may be eliminated. On the other hand, the state in which the control elements 62A and 62B are in contact with each other and the control elements 63A and 63B are in contact with each other may be maintained, and the wings 32 and 33 may also be maintained. The expansion diameter of the balloon 3 in this state is larger than the intermediate diameter Rmid (see FIG. 2) and smaller than the maximum diameter Rmax (see FIG. 3). Hereinafter, the expansion diameter of the balloon 3 in this state is referred to as the "intermediate diameter Rmid (1)".

For example, when an external force of a second strength F2 smaller than the first strength F1 acts on the balloon 3, the magnetic or electrostatic force no longer acts between the control elements 61A and 61B, but also between the control elements 62A and 62B, and they may separate from each other. In this case, the balloon 3 may further expand from the state shown in FIG. 6, and the control elements 62A and 62B may further separate from each other, eliminating the wings 32 (see FIG. 2). Note that the state in which the control elements 63A and 63B are in contact with each other is maintained, and the wings 33 are maintained. The expansion diameter of the balloon 3 in this state is larger than the intermediate diameter Rmid(1) and smaller than the maximum diameter Rmax. Hereinafter, the expansion diameter of the balloon 3 in this state is referred to as the "intermediate diameter Rmid(2)".

Also, for example, when an external force of a predetermined third strength F3, which is smaller than the second strength F2, acts on the balloon 3, all of the control elements 60A, 60B may move away from each other. In this case, the balloon 3 is in a maximum diameter state, and the expanded diameter is the maximum diameter Rmax.

As described above, the balloon 3 can be brought into a partially folded state with respect to the maximum diameter of the balloon 3 (see FIG. 2) in response to the application of an external force of the first strength F1 or the second strength F2, which is greater than the third strength F3. In this case, the balloon catheter 1A can switch the expansion diameter of the balloon 3 to any one of the intermediate diameter Rmid, Rmid(1), Rmid(2), and the maximum diameter Rmax.

In the above, the expansion diameter of the balloon 3 may be reversibly controlled between the intermediate diameters Rmid(0), Rmid(1), Rmid(2), and the maximum diameter Rmax. For example, the expansion diameter of the balloon 3 may be controlled in sequence to Rmid, Rmid(1), Rmax, Rmid(2), and Rmax to expand multiple stenotic lesions.

<Second Modification>
A second modified example of the balloon catheter 1A will be described. In the second modified example shown in Fig. 7(A), a plurality of control elements 6D are used instead of the plurality of control elements 6C in the diameter control member 6. The other configurations except for the plurality of control elements 6C are the same as those of the balloon catheter 1A described in the above embodiment. As shown in Fig. 7(A), the plurality of control elements 6D include a plurality of pairs of control elements 65, and each pair of control elements 65 is composed of control elements 65A and 65B.

The control elements 65A and 65B each have a cylindrical shape with a portion cut out, and extend in the extension direction. More specifically, the control elements 65A and 65B have a cylindrical shape with a portion cut out by a plane extending parallel to the axis C1 of the cylinder. A cross section of the control elements 65A and 65B cut by a plane perpendicular to the axis C1 includes an arc 651 and a chord 652 extending between both ends of the arc 651. When viewed from the direction in which the axis C1 extends, the angle θ between the two straight lines extending from the axis C1 toward both ends Q of the chord 652 is not particularly limited, but is preferably within the range of 90° to 180°.

For example, magnetic force is preferably used as the attractive force acting between the control elements 65A and 65B. For example, when an external magnetic field is acting on the multiple control elements 6D, magnetic force acts as an attractive force between the control elements 65A and 65B. In addition, since both ends Q of the string 652 become magnetic poles, a strong magnetic force acts between the control elements 65A and 65B in a direction that causes them to approach each other. As a result, the control elements 65A and 65B come into contact with each other with their respective strings 652 facing each other. On the other hand, when an external magnetic field is not acting on the multiple control elements 6D, for example, the magnetic force between the control elements 65A and 65B is ineffective. In this case, the control elements 65A and 65B are separated from each other.

As described above, each pair of control elements 65 can exert a strong magnetic force between the control elements 65A and 65B. Therefore, the balloon catheter 1A can stably maintain the state in which the control elements 65A and 65B are in contact.

<Third Modification>
A third modified example of the balloon catheter 1A will be described. In the third modified example shown in Figures 7(B) and (C), a plurality of control elements 6E (see Figure 7(B)) and 6F (see Figure 7(C)) are used instead of the plurality of control elements 6C in the diameter control member 6. The rest of the configuration except for the plurality of control elements 6C is the same as that of the balloon catheter 1A described in the above embodiment.

As shown in FIG. 7B, the plurality of control elements 6E includes a plurality of pairs of control elements 66, and each pair of control elements 66 is composed of control elements 66A and 66B. As shown in FIG. 7C, the plurality of control elements 6F includes a plurality of pairs of control elements 67, and each pair of control elements 67 is composed of control elements 67A and 67B. Frictional force is preferably used as the attractive force acting between the control elements 66A and 66B and between the control elements 67A and 67B. Furthermore, a circumferential force acting on the side surface 30 of the balloon 3 during expansion (hereinafter referred to as "expansion force") is used as an external force for switching between a state in which the control elements 66A and 66B and the control elements 67A and 67B are in contact with each other and a state in which they are separated from each other.

As shown in FIG. 7B, the control elements 66A and 66B have a rectangular column shape and extend in the extension direction. A recess 661 is formed on one surface Sa of the control element 66A, recessed toward the surface Ua opposite the surface Sa. The cross-sectional shape of the recess 661 is circular, and the diameter is constant regardless of the depth. One surface Sb of the control element 66B has a protrusion 662 protruding in the opposite direction to the surface Ub opposite the surface Sb. The shape of the protrusion 662 is cylindrical, and the diameter is constant regardless of the height. The protrusion 662 of the control element 66B can be fitted into the recess 661 of the control element 66A. When the protrusion 662 is fitted into the recess 661, the control elements 66A and 66B come into contact with each other. In addition, the control elements 66A and 66B are difficult to separate due to the frictional force acting on the contact surfaces that contact each other.

As shown in FIG. 7C, the control elements 67A and 67B have a rectangular column shape and extend in the extension direction. One face Fa of the control element 67A has multiple recesses 671 recessed toward the face Ea opposite to the face Fa. The cross-sectional shape of each of the multiple recesses 671 is circular, and the deeper the recesses, the smaller the diameter. One face Fb of the control element 67B has multiple protrusions 672 protruding in the opposite direction to the face Eb opposite to the face Fb. Each of the multiple protrusions 672 has a conical shape, and the larger the height, the smaller the diameter. The multiple protrusions 672 of the control element 67B can be fitted into the multiple recesses 671 of the control element 67A. The control elements 67A and 67B come into contact with each other when the multiple protrusions 672 are fitted into the multiple recesses 671. In addition, the control elements 67A and 67B are difficult to separate due to frictional forces acting on the contact surfaces that contact each other.

An example of the use of multiple control elements 6E and 6F will be described using multiple control elements 6E as an example. In the balloon 3 in a contracted state, the convex portion 662 fits into the concave portion 661, and the control elements 66A and 66B are in contact with each other. In this state, the supply of compressed fluid to the balloon 3 begins, and the balloon 3 enters an expanded state. However, the control elements 66A and 66B are in contact with each other, and are difficult to separate due to the frictional force acting on their contact surfaces. As a result, the balloon 3 enters an intermediate diameter state, and the expanded diameter becomes the intermediate diameter Rmid (see FIG. 2).

Next, more compressed fluid is supplied to the balloon 3 to separate the control elements 66A, 66B. In this case, the balloon 3 expands, and a circumferential force (expansion force) acts on the side surface 30. When this expansion force becomes greater than the frictional force between the control elements 66A, 66B, the control elements 66A, 66B separate. In this case, the balloon 3 reaches its maximum diameter state, and the expanded diameter becomes the maximum diameter Rmax.

As described above, the multiple control elements 6E can stably maintain the multiple control elements 6E in a close state by utilizing the frictional force between the control elements 66A and 66B. Furthermore, by fitting the recessed portion 661 and the protruding portion 662 together, the frictional force can be efficiently applied between the control elements 66A and 66B.

In order to allow the frictional force to act efficiently between the control elements 66A and 66B, the contact surfaces between them do not need to be smooth; it is preferable for them to have slight irregularities, for example.

<Fourth Modification>
Balloon catheters 1B and 1C according to a fourth modification will be described with reference to Fig. 8. The balloon catheters 1B and 1C each have a different shape of a control element from the above embodiment.

In the balloon catheter 1B shown in FIG. 8(A), the control elements 71 are cylindrical and extend in the stretching direction. The length of the control elements 71 in the stretching direction is shorter than the length of the expansion region 3B of the balloon 3 in the stretching direction. The control elements 71 are arranged not only in the circumferential direction of the balloon 3, but also in the stretching direction. In other words, the control elements 71 have a shape in which each of the control elements 6C described in the above embodiment is divided into multiple parts in the stretching direction. Furthermore, in the balloon catheter 1B, the control elements 71 are provided not only in the expansion region 3B of the balloon 3, but also in the distal cone region 3A and the proximal cone region 3C. In the balloon catheter 1C shown in FIG. 8(B), the control elements 72 are spherical. The control elements 72 are randomly fixed to the side surface 30 of the balloon 3.

The balloon catheter 1B having multiple control elements 71 shown in FIG. 8(A) has better tracking ability with respect to the vascular passage 9 than the balloon catheter 1A. Also, the balloon catheter 1C having multiple control elements 72 shown in FIG. 8(B) has even better tracking ability with respect to the vascular passage 9 than the balloon catheter 1B.

<Other Modifications>
The present invention is not limited to the above-described embodiment, and various modifications are possible. Below, modifications will be described based on the balloon catheter 1A, but it goes without saying that the modifications can be applied to the balloon catheters 1B, 1C, etc. as appropriate.

The balloon catheter 1A may not have the outer tube 21 and the inner tube 22. In this case, the balloon catheter 1A may have at least the balloon 3 and the diameter control member 6. The total number of the control elements 6C is not limited to six, and may be any number equal to or greater than two. However, in order to stabilize the intermediate diameter state, the total number of the control elements 6C is preferably equal to or greater than four and equal to or less than ten. Furthermore, it is most preferable that the number of the control elements 6C is six. The control elements 6C are not limited to being fixed to the side surface 30 of the balloon 3, and may be fixed to the inner surface of the balloon 3, or may be incorporated inside the balloon 3. The distal end of the control elements 6C may be connected to the vicinity of the distal end 221 of the inner tube 22. The proximal end of the control elements 6C may be connected to the vicinity of the distal end 211 of the outer tube 21.

The material of the multiple control elements 6C is preferably a rigid metal or resin so that the expansion diameter of the balloon 3 can be stably maintained at the intermediate diameter Rmid when the balloon 3 is expanded. In addition, taking into consideration the ability of the balloon 3 to follow the blood vessel 9, it is preferable to use a shape memory alloy such as a nickel-titanium alloy or a hard resin.

The multiple control elements 6C may be radiopaque. In this case, the position of the balloon 3 inside the body during treatment can be easily grasped, making it possible to place the balloon 3 at an appropriate position for the target stenotic lesion. In addition, since the expansion diameter of the balloon 3 during treatment can be easily grasped, an external force can be applied to the multiple control elements 6C to achieve the target expansion diameter.

The multiple control elements 6C may have the function of crushing or incising hardened stenotic lesions. In this case, it is preferable that the multiple control elements 6C are made of a hard material and have a pointed tip.

The shape of the multiple control elements 6C is not limited to a cylindrical shape, and may be a prismatic shape (e.g., a triangular prism). A hollow extending along the extension direction may be formed inside the multiple control elements 6C. In other words, the multiple control elements 6C may have a hollow shape.

When multiple control elements 6C are in close proximity, the control elements 60A, 60B do not need to be in contact with each other, and a gap may be formed between them. In this case, it is sufficient that the distance between the control elements 60A, 60B in the separated state is greater than the distance between the control elements 60A, 60B in the close proximity state.

The multiple control elements 6C do not have to be arranged at equal intervals in the circumferential direction when in a separated state. For example, the distance between a pair of control elements 61, 62, 63 may be shorter or longer than the distance between the other control elements.

The multiple control elements 6C may be provided only in a portion of the expansion region 3B of the balloon 3 in the stretching direction. In this case, the multiple control elements 6C make it possible to vary the expansion diameter of the balloon 3 for each portion in the stretching direction.

The balloon 3 may be coated with a drug only on a portion of the side surface 30. Different drugs may be coated on the second exposed portions 31B, 32B, and 33B of the balloon 3. No drug may be coated on the side surface 30 of the balloon 3. The hardness of the multiple control elements 6C may be the same as that of the balloon 3, or may be softer than that of the balloon 3.

In the balloon catheter 1A, when no external magnetic field is acting on the multiple control elements 6C, a magnetic force or electrostatic force may act as an attractive force between all of the control elements 60A, 60B. In this state, when compressed fluid is supplied to the balloon 3 and the balloon 3 is in an expanded state, the balloon 3 may be in an intermediate diameter state. On the other hand, in the balloon catheter 1A, when an external magnetic field is acting on the multiple control elements 6C, all of the magnetic forces or electrostatic forces between all of the control elements 60A, 60B may be ineffective. In this state, when compressed fluid is supplied to the balloon 3 and the balloon 3 is in an expanded state, the balloon 3 may be in a maximum diameter state.

1A, 1B, 1C: balloon catheter 3: balloon 6: diameter control member 6C, 6D, 6E, 6F: control element 30A, 31A, 32A, 33A: first exposed portion 30B, 31B, 32B, 33B: second exposed portion 661, 671: recessed portion 662, 672: protruding portion G: guide wire Q: both ends

Claims (14)

a balloon expandable and contractable between an expanded state and a contracted state;
A diameter control member for controlling an expansion diameter of the balloon in the expanded state,
A plurality of control elements are fixed to different positions of the balloon in a circumferential direction,
a separated state in which the respective control elements are separated from each other in the circumferential direction and a close state in which a distance between at least two control elements in one or more sets is smaller than the separated state are switched in response to a change in an external force acting between the at least two control elements;
In the separated state, the balloon is in a maximum diameter state in which the expanded diameter is a maximum diameter,
a diameter control member that controls the balloon to be in an intermediate diameter state in which the expanded diameter is an intermediate diameter smaller than the maximum diameter when the balloon is in the approaching state ;
the external force is an expansion force of the balloon,
The diameter control member controls the expansion diameter of the balloon by frictional force,
The at least two control elements are
a first control element including a recess;
A second control element having a protrusion that can be fitted into the recess;
A balloon catheter comprising at least a balloon expandable and contractable between an expanded state and a contracted state;
A diameter control member for controlling an expansion diameter of the balloon in the expanded state,
A plurality of control elements are fixed to different positions of the balloon in a circumferential direction,
a separated state in which the respective control elements are separated from each other in the circumferential direction and a close state in which a distance between at least two control elements in one or more sets is smaller than the separated state are switched in response to a change in an external force acting between the at least two control elements;
In the separated state, the balloon is in a maximum diameter state in which the expanded diameter is a maximum diameter,
a diameter control member that controls the balloon to be in an intermediate diameter state in which the expanded diameter is an intermediate diameter smaller than the maximum diameter when the balloon is in the approaching state;
the external force is an external magnetic field;
A balloon catheter , characterized in that the diameter control member controls the expansion diameter of the balloon by magnetic force . 3. The balloon catheter according to claim 2, wherein the control elements are made of a magnetic material. a balloon expandable and contractable between an expanded state and a contracted state;
A diameter control member for controlling an expansion diameter of the balloon in the expanded state,
A plurality of control elements are fixed to different positions of the balloon in a circumferential direction,
a separated state in which the respective control elements are separated from each other in the circumferential direction and a close state in which a distance between at least two control elements in one or more sets is smaller than the separated state are switched in response to a change in an external force acting between the at least two control elements;
In the separated state, the balloon is in a maximum diameter state in which the expanded diameter is a maximum diameter,
a diameter control member that controls the balloon to be in an intermediate diameter state in which the expanded diameter is an intermediate diameter smaller than the maximum diameter when the balloon is in the approaching state;
the external force is the passage of current through the plurality of control elements;
A balloon catheter , characterized in that the diameter control member controls the expansion diameter of the balloon by electrostatic force . The balloon catheter according to claim 4, wherein the plurality of control elements are formed of a conductive material or a charged material. The plurality of control elements include:
It has a cylindrical shape with a part cut out by a plane extending parallel to the axis,
In a cross section perpendicular to the axis, the angle between two straight lines extending from the axis to both ends of the chord corresponding to the plane is within a range of 90° to 180°.
6. The balloon catheter according to claim 2, wherein the balloon catheter is a catheter having a diameter of 10 mm or less. the plurality of control elements includes four or more control elements;
7. The balloon catheter according to claim 1, wherein in the close together state, a distance between two or more sets of two control elements is smaller than that in the separated state. The plurality of control elements include:
8. The balloon catheter according to claim 1, wherein in the separated state, the lugs are arranged at equal intervals in the circumferential direction. The at least two control elements are
9. The balloon catheter according to claim 1, wherein the two members contact each other in the approaching state. 10. The balloon catheter according to claim 1, wherein at least a portion of the balloon is coated with a drug. The balloon is
a first exposed portion that is exposed in the intermediate diameter state;
a second exposed portion that is not exposed in the intermediate diameter state and is exposed in the maximum diameter state,
The balloon catheter according to claim 10 , wherein different drugs are applied to the first exposed portion and the second exposed portion. 12. The balloon catheter of claim 1, wherein the control elements are stiffer than the balloon. the plurality of control elements being stiffer than the balloon;
11. The balloon catheter according to claim 10 , wherein the control elements are coated with the same drug as that coated on the balloon. the plurality of control elements being stiffer than the balloon;
11. The balloon catheter of claim 10 , wherein the control elements are coated with a drug different from the drug coated on the balloon.

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