Patent Description:
A catheter ablation therapy is a treatment method that uses a catheter inserted into a body to ablate a target site in the human body. As an example, a target site is destroyed by ablation to treat diseases such as arrhythmia due to atrial fibrillation, endometriosis, cancer, etc. As disclosed in <CIT>, <CIT> and <CIT>, a balloon catheter having a distal end to which a balloon is attached is known as a catheter used for catheter ablation therapy.

A balloon catheter has a catheter shaft that is inserted into a human body, and a balloon provided at a distant end of the catheter shaft. The catheter shaft is formed of a long flexible base member. The catheter shaft is inserted into a human body and is guided to a vicinity of a target site, and then a liquid is supplied into the balloon through an inside space of the catheter shaft, so that the balloon is inflated. Since a temperature of the liquid in the balloon has been controlled, a surface temperature of the balloon can be controlled. By bringing the balloon whose surface temperature has been adjusted to a predetermined one into contact with a circumferential target site, e.g., a connection of a vein to an atrium, the circumferential target site can be ablated at once.

When a distant end portion of the balloon catheter is curved, it may cause inconveniences such as loss of control of the balloon surface temperature. Thus, to be able to detect curvature of a distant end portion of a balloon catheter is one of the needs for balloon catheters. Other devices including a long flexible base member (for example, catheter of another type, medical endoscope, industrial endoscope, etc.) have a similar need. Although a distant end portion of a balloon catheter can be seen through a radioscopic image, the radioscopic image provides only two-dimensional information. Thus, it is often difficult to find out, from a radioscopic image, whether the distant end portion is curved, and/or in which direction the distant end portion is curved. <CIT> discloses a medical endoscope that detects curvature of a long base member by using an optical fiber disposed in the base member. However, the base member is required to have a certain degree of thickness (external dimensions) in order to detect curvature by means an optical fiber disposed in the base member. Thus, it is difficult to apply the aforementioned curvature detection method to a device, such as a balloon catheter, on which severe restrictions on external dimensions of a base member (catheter shaft) are imposed.

Document <CIT> discloses a curvature detection system as set out in the preamble of claim <NUM>.

The present invention has been made in consideration of the above points. The object of the present invention is to detect curvature of a base member with increase in external dimensions of the base member minimized.

A curvature detection system according to the present invention comprises: a base member having a longitudinal direction; a first linear member extending in the longitudinal direction; and a second linear member extending in the longitudinal direction. The first linear member is fixed to the base member at a first fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on one side of the first fixed position in the longitudinal direction. The second linear member is fixed to the base member at a second fixed position different from the first fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on the one side of the second fixed position in the longitudinal direction. The curvature detection system is capable of detecting curvature of the base member between the first fixed position and the second fixed position based on change in a relative position between the first linear member and the second linear member.

In the curvature detection system of the present invention, the first linear member and the second linear member may be disposed in one or more lumens provided in the base member.

In the curvature detection system of the present invention, the first linear member and the second linear member may be disposed in separate lumens.

In the curvature detection system of the present invention, the base member may be a cylindrical member having a wall delimiting a hollow.

In the curvature detection system of the present invention, the first linear member and the second linear member may be disposed in one or more lumens provided in the base member, and the one or more lumens may be formed in the wall.

In the curvature detection system of the present invention, markers indicating a relative position between the first linear member and the second linear member may be provided on the first linear member and the second linear member.

The curvature detection system of the present invention may comprise a third linear member and a fourth linear member, the third and fourth linear members extending along the longitudinal direction at a position/positions different from a position/positions of the first linear member and the second linear member in a circumferential direction of the wall, wherein: the third linear member is fixed to the base member at the first fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on the one side of the first fixed position in the longitudinal direction; the fourth linear member is fixed to the base member at the second fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on the one side of the second fixed position in the longitudinal direction; and the base member with the curvature detection function is capable of detecting curvature of the base member between the first fixed position and the second fixed position based on change in a relative position between (ends on the above one side of) the third linear member and the fourth linear member.

In this case, the third linear member and the fourth linear member may be disposed in other one or more lumens provided at a position/positions different from a position/positions of the one or more lumens for the first linear member and the second linear member in the circumferential direction of the wall.

In addition, in this case, markers indicating a relative position between the third linear member and the fourth linear member may be provided on the third linear member and the fourth linear member.

Alternatively, a curvature detection system of the present invention comprises: a sensor configured to detect change in a relative position between the first linear member and the second linear member.

A device of the present invention comprises the aforementioned curvature detection system.

A balloon catheter of the present invention comprises:.

The present invention makes it possible to detect curvature of the base member with increase in external dimensions of the base member minimized.

A first embodiment of the present invention will be described hereunder with reference to specific examples shown in the drawings. In the drawings attached to the specification, a scale dimension, an aspect ratio and so on are changed and exaggerated from the actual ones, for the convenience of easiness in illustration and understanding. In addition, terms used herein to specify shapes, geometric conditions and their degrees, e.g., "parallel", "orthogonal", "same", etc., and values of a length and an angle are not limited to their strict definitions, but construed to include a range capable of exerting a similar function.

A curvature detection system <NUM> shown in <FIG> has a base member with a curvature detection function <NUM>, a distance displacement sensor <NUM>, and a display device <NUM>. In addition, the base member with the curvature detection function <NUM> has a base member <NUM> having a longitudinal direction LD, a first linear member <NUM> extending along the longitudinal direction LD, and a second linear member <NUM> extending in the longitudinal direction LD.

The base member <NUM> can be curved. The base member <NUM> can be made of various materials, such as metal, ceramic, resin, etc., depending on an application of the base member with the curvature detection function <NUM>.

In the illustrated example, the base member <NUM> is a cylindrical member having a wall <NUM> delimiting a hollow 3a. It goes without saying that, not limited to the cylindrical shape, the base member <NUM> can have another shape such as a plate-like shape, a pillar shape, etc..

The base member <NUM> is provided with a first lumen 4a and a second lumen 4b which extend adjacently to each other in the longitudinal direction LD. The first lumen 4a and the second lumen 4b are formed in the wall <NUM> of the base member <NUM>.

The first linear member <NUM> is disposed in the first lumen 4a, and the second linear member <NUM> is disposed in the second lumen 4b. Since the linear member <NUM>, <NUM> are disposed in the lumens 4a, 4b, the risk of damaging the linear members <NUM>, <NUM> is reduced. In addition, since the linear members <NUM>, <NUM> are disposed in the lumens 4a, 4b separated from one another, the risk of causing the linear members <NUM>, <NUM> to be entangled is reduced.

The first linear member <NUM> has a first end 6a and a second end 6b positioned on one side of the first end 6a in the longitudinal direction. The first end 6a of the first linear member <NUM> is fixed to a first fixed position P1 of the base member <NUM> in the first lumen 4a. The rest part of the first linear member <NUM>, which includes the second end 6b, is disposed in the first lumen 4a so that the rest part is relatively movable with respect to the base member <NUM> in the longitudinal direction LD.

The second linear member <NUM> also has a first end 7a and a second end 7b positioned on the one side of the first end 7a in the longitudinal direction LD. The first end 7a of the second linear member <NUM> is fixed to a second fixed position P2 of the base member <NUM> in the second lumen 4b. The rest part of the second linear member <NUM>, which includes the second end 7b, is disposed in the second lumen 4b so that the rest part is relatively movable with respect to the base member <NUM> and the first linear member <NUM> in the longitudinal direction LD. The second fixed position P2 is located at a position apart from the first fixed position P1 in the longitudinal direction Ld. In the illustrated example, the second fixed poison P2 is positioned on the one side of the first fixed position P1 along the longitudinal direction LD.

The first linear member <NUM> and the second linear member <NUM> are made of a low-stretch material compared to the base member <NUM> and can be curved along the base member <NUM> when it is curved. The first linear member <NUM> and the second linear member <NUM> can be made of various materials, such as metal, resin, etc., depending on an application of the base member with the curvature detection function <NUM>. The first linear member <NUM> and the second linear member <NUM> are preferably made of the same material.

In the illustrated example, lengths of the first linear member <NUM> and the second linear member <NUM> are determined in such a manner that, as shown in <FIG> and <FIG>, the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> are located at the same position in the longitudinal direction LD, with the base member <NUM> not curved at any position in the longitudinal direction LD. However, as described later, the present invention is not limited to this example, as long as it is possible to detect change in a relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM>.

The base member with the curvature detection function <NUM> as structured above can detect curvature of the base member <NUM> between the first fixed position P1 and the second fixed position P2, based on change in a relative position between the second ends 6b, 7b of the first linear member <NUM> and the second linear member <NUM>. In particular, curvature of the base member <NUM> in a vertical direction VD can be detected.

In the below description, a side of the base member <NUM>, on which the first linear member <NUM> and the second linear member <NUM> are provided, is referred to as "upper side", and a side opposed to the upper side is referred to as "lower side". In addition, a direction directed from the lower side toward the upper side is referred to as "upward", and a direction directed from the upper side toward the lower side is referred to as "downward". In <FIG>, although the first linear member <NUM> and the second linear member <NUM> are shown at different positions in the vertical direction for the sake of facilitating understanding, note that the first linear member <NUM> and the second linear member <NUM> are located at positions that are overlapped with each other in a side view of the base member with the curvature detection function <NUM>.

With reference to <FIG>, relative movement between the second ends 6b, 7b of the first linear member <NUM> and the second linear member <NUM> due to curvature of the base member <NUM> is described.

As shown in <FIG>, when the base member <NUM> is not curved at any position in the longitudinal direction LD, the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> are located at the same position in the longitudinal direction LD, as described above.

As shown in <FIG>, when the base member <NUM> is curved downward in an area A between the first fixed position P1 and the second fixed position P2, the upper side region of the area A (the region where the first linear member <NUM> is disposed) is stretched due to the curvature. Thus, the second end 6b of the first linear member <NUM>, which extends in the area A, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. On the other hand, the second end 7b of the second linear member <NUM>, which does not extend in the area A, does not move with respect to the base member <NUM>. As a result, the second end 6b of the first linear member <NUM> moves relatively with respect to the second end 7b of the second linear member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD and the relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> changes.

In addition, as shown in <FIG>, when the base member <NUM> is curved upward in the area A, the upper side region of the area A (the region where the first linear member <NUM> is disposed) is contracted due to the curvature. Thus, the second end 6b of the first linear member <NUM>, which extends in the area A, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. On the other hand, the second end 7b of the second linear member <NUM>, which does not extend in the area A, does not move with respect to the base member <NUM>. As a result, the second end 6b of the first linear member <NUM> moves relatively with respect to the second end 7b of the second linear member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD and the relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> changes.

In addition, as shown in <FIG>, when the base member <NUM> is curved downward in an area B which is positioned on the one side (right side in <FIG>) of the second fixed position P2 in the longitudinal direction LD, the upper side region of the area B (the region where the first linear member <NUM> and the second linear member <NUM> are disposed) is stretched due to the curvature. Thus, the second end 6b of the first linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. Similarly, the second end 7b of the second linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. A distance moved by the second end 7b of the second linear member <NUM> with respect to the base member <NUM> is the same as a distance moved by the second end 6b of the first linear member <NUM> with respect to the base member <NUM>. As a result, the relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> does not change.

In addition, as shown in <FIG>, when the base member <NUM> is curved upward in the area B, the upper side region of the area B (the region where the first linear member <NUM> and the second linear member <NUM> are disposed) is contracted due to the curvature. Thus, the second end 6b of the first linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. Similarly, the second end 7b of the second linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. A distance moved by the second end 7b of the second linear member <NUM> with respect to the base member <NUM> is the same as a distance moved by the second end 6b of the first linear member <NUM> with respect to the base member <NUM>. As a result, the relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> does not change.

Therefore, it is possible to detect whether the base member <NUM> is curved in the area A by detecting change in a relative position between the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM>. In addition, it is possible to detect a direction of curvature (upward or downward) of the base member in the area A by detecting a direction of displacement of the second end 6b of the first linear member <NUM> with respect to the second end 7b of the second linear member <NUM>.

Further, when the base member <NUM> is curved in the area A, the amount of displacement of the second end 6b of the first linear member <NUM> with respect to the second end 7b of the second linear member <NUM> depends on a degree of the curvature of the area A (in other words, an angle of a direction in which a center axis X of the base member <NUM> at the fixed position P2 extends, with respect to a direction in which the center axis X of the base member <NUM> at the fixed position P1 extends). Thus, the degree of curvature of the base member <NUM> in the area A can be detected by detecting the amount of the displacement of the second end 6b with respect to the second end 7b.

Next, the distance displacement sensor <NUM> is described. The distance displacement sensor <NUM> detects change in a relative position between the second ends 6b, 7b of the first linear member <NUM> and the second linear member <NUM>. The distance displacement sensor <NUM> includes a first sensor 8a and a second sensor 8b, and is capable of detecting change in a relative position between the first sensor 8a and the second sensor 8b. The first sensor 8a is fixed to the second end 6b of the first linear member <NUM>, and the second sensor 8b is fixed to the second end 7b of the second linear member <NUM>. The distance displacement sensor <NUM> is electrically connected to the display device <NUM>. When a relative position of the first sensor 8a with respect to the second senor 8b changes, the distance displacement sensor <NUM> inputs, to the display device <NUM>, a signal corresponding to a direction and the amount of displacement of the first sensor 8a with respect to the second sensor 8b.

The display device <NUM> determines the direction and the degree of curvature of the base member <NUM> in the area A based on the signal inputted by the distance displacement sensor <NUM>, and displays them on a display 9a.

In the illustrated example, the display device <NUM> displays the curvature direction detected by means of the distance displacement sensor <NUM> as "UP", "MID" or "DOWN". Specifically, when the base member <NUM> is not curved in the area A as shown in <FIG>, <FIG> and <FIG>, the display device <NUM> indicates the curvature direction as "MID". When the base member <NUM> is curved downward in the area A as shown in <FIG>, the display device <NUM> indicates the curvature direction as "DOWN". When the base member <NUM> is curved upward in the area A as shown in <FIG>, the display device <NUM> indicates the curvature direction as "UP".

In addition, in the illustrated example, the display device <NUM> displays the curvature degree detected by means of the distance displacement sensor <NUM> as "LARGE" or "SMALL". Specifically, when the amount of displacement of the first sensor 8a with respect to the second sensor 8b (thus the amount of displacement of the second end 6b of the first linear member <NUM> with respect to the second end 7b of the second linear member <NUM>) is zero (this is the cases of <FIG>, <FIG> and <FIG>), the display device <NUM> does not display the curvature degree. When the amount of displacement of the first sensor 8a with respect to the second sensor 8b is greater than <NUM> and less than a predetermined value, the display device <NUM> indicates the curvature degree as "SMALL". When the amount of displacement of the first sensor 8a with respect to the second sensor 8b is equal to or greater than the predetermined value, the display device <NUM> indicates the curvature degree as "LARGE".

Next, a curvature detection system <NUM> according to a second embodiment is described with reference to <FIG>.

An example shown in <FIG> differs from the curvature detection system <NUM> shown in <FIG> in that a base member with a curvature detection function <NUM> further has a third linear member <NUM> extending in a longitudinal direction LD, a fourth linear member <NUM> extending in the longitudinal direction LD, and a second distance displacement sensor <NUM>. Other configurations are substantially the same as those of the curvature detection system <NUM> shown in <FIG>. In the example shown in <FIG>, the same numerals are given to the same parts as those of the first embodiment shown in <FIG>, and detailed description thereof is omitted.

In the example shown in <FIG>, a base member <NUM> further has a third lumen 4c and a fourth lumen 4d which extend adjacently to each other in the longitudinal direction LD. The third lumen 4c and the fourth lumen 4d are formed in a wall <NUM> of the base member <NUM>.

As shown in <FIG>, the third lumen 4c and the fourth lumen 4d are located at positions different from the positions of the first lumen 4a and the second lumen 4b in a circumferential direction RD of the cylindrical part <NUM> of the base member <NUM>. In the illustrated example, the third lumen 4c and the fourth lumen 4d are apart from the first lumen 4a and the second lumen 4b by <NUM> degrees clockwise around the center axis X of the base member <NUM>, when the base member <NUM> is observed from one end (an end on the area B side) in the longitudinal direction LD.

The third linear member <NUM> is disposed in the third lumen 4c, and the fourth linear member <NUM> is disposed in the fourth lumen 4d. Since the linear member <NUM>, <NUM> are disposed in the lumens 4c, 4d, the risk of damaging the linear members <NUM>, <NUM> is reduced. In addition, since the linear members <NUM>, <NUM> are disposed in the lumens 4c, 4d separated from one another, the risk of causing the linear members <NUM>, <NUM> to be entangled is reduced.

The third linear member <NUM> has a first end 16a and a second end 16b positioned on one side of the first end 16a in the longitudinal direction LD. The first end 16a of the third linear member <NUM> is fixed to the first fixed position P1 of the base member <NUM> in the third lumen 4c. The rest part of the third linear member <NUM>, which includes the second end 16b, is disposed in the third lumen 4c so that the rest part is relatively movable with respect to the base member <NUM> in the longitudinal direction LD.

The fourth linear member <NUM> also has a first end 17a and a second end 17b positioned on the one side of the first end 17b in the longitudinal direction LD. The first end 17a of the fourth linear member <NUM> is fixed to the second fixed position P2 of the base member <NUM> in the fourth lumen 4d. The rest part of the fourth linear member <NUM>, which includes the second end 17b, is disposed in the fourth lumen 4d so that the rest part is relatively movable with respect to the base member <NUM> and the third linear member <NUM> in the longitudinal direction LD.

The third linear member <NUM> and the fourth linear member <NUM> are made of a low-stretch material compared to the base member <NUM> and can be curved along the base member <NUM> when it is curved. Similarly to the first linear member <NUM> and the second linear member <NUM>, the third linear member <NUM> and the fourth linear member <NUM> can be made of various materials, such as metal, resin, etc., depending on an application of the base member with the curvature detection function <NUM>. The third linear member <NUM> and the fourth linear member <NUM> are preferably made of the same material.

In the illustrated example, lengths of the third linear member <NUM> and the fourth linear member <NUM> are determined in such a manner that, as shown in <FIG> and <FIG>, the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> are located at the same position in the longitudinal direction LD, with the base member <NUM> not curved at any position in the longitudinal direction LD. However, as described later, the present invention is not limited to this example, as long as it is possible to detect change in a relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM>.

The base member with the curvature detection function <NUM> as structured above can detect curvature of the base member <NUM> between the first fixed position P1 and the second fixed position P2, based on change in a relative position between the second ends 16b, 17b of the third linear member <NUM> and the fourth linear member <NUM>. In particular, curvature of the base member <NUM> in a horizontal direction HD can be detected.

In the below description, a side of the base member <NUM>, on which the third linear member <NUM> and the fourth linear member <NUM> are provided, is referred to as "right side", and a side opposed to the right side is referred to as "left side". In addition, a direction directed from the left side toward the right side is referred to as "rightward", and a direction directed from the right side toward the left side is referred to as "leftward". In <FIG>, although the third linear member <NUM> and the fourth linear member <NUM> are shown at different positions in the horizontal direction for the sake of facilitating understanding, note that the third linear member <NUM> and the fourth linear member <NUM> are located at positions that are overlapped with each other in a top view of the base member with the curvature detection function <NUM>.

With reference to <FIG>, relative movement between the third linear member <NUM> and the fourth linear member <NUM> due to curvature of the base member <NUM> is described.

As shown in <FIG>, when the base member <NUM> is not curved at any position in the longitudinal direction LD, the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> are located at the same position in the longitudinal direction LD, as described above.

As shown in <FIG>, when the base member <NUM> is curved leftward in the area A, the right side region of the area A (the region where the third linear member <NUM> is disposed) is stretched due to the curvature. Thus, the second end 16b of the third linear member <NUM>, which extends in the area A, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. On the other hand, the second end 17b of the fourth linear member <NUM>, which does not extend in the area A, does not move with respect to the base member <NUM>. As a result, the second end 16b of the third linear member <NUM> moves relatively with respect to the second end 17b of the fourth linear member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD and the relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> changes.

In addition, as shown in <FIG>, when the base member <NUM> is curved rightward in the area A, the right side region of the area A (the region where the third linear member <NUM> is disposed) is contracted due to the curvature. Thus, the second end 16b of the third linear member <NUM>, which extends in the area A, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. On the other hand, the second end 17b of the fourth linear member <NUM>, which does not extend in the area A, does not move with respect to the base member <NUM>. As a result, the second end 16b of the third linear member <NUM> moves relatively with respect to the second end 17b of the fourth linear member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD and the relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> changes.

In addition, as shown in <FIG>, when the base member <NUM> is curved leftward in the area B, the right side region of the area B (the region where the third linear member <NUM> and the fourth linear member <NUM> are disposed) is stretched due to the curvature. Thus, the second end 16b of the third linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. Similarly, the second end 17b of the fourth linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the other side (left side in <FIG>) in the longitudinal direction LD. A distance moved by the second end 17b of the fourth linear member <NUM> with respect to the base member <NUM> is the same as a distance moved by the second end 16b of the third linear member <NUM> with respect to the base member <NUM>. As a result, the relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> does not change.

In addition, as shown in <FIG>, when the base member <NUM> is curved rightward in the area B, the right side region of the area B (the region where the third linear member <NUM> and the fourth linear member <NUM> are disposed) is contracted due to the curvature. Thus, the second end 16b of the third linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. Similarly, the second end 17b of the fourth linear member <NUM>, which extends in the area B, moves with respect to the base member <NUM> to the one side (right side in <FIG>) in the longitudinal direction LD. A distance moved by the second end 17b of the fourth linear member <NUM> with respect to the base member <NUM> is the same as a distance moved by the second end 16b of the third linear member <NUM> with respect to the base member <NUM>. As a result, the relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM> does not change.

Therefore, it is possible to detect whether the base member <NUM> is curved in the area A by detecting change in a relative position between the second end 16b of the third linear member <NUM> and the second end 17b of the fourth linear member <NUM>. In addition, it is possible to detect a direction of curvature (rightward or leftward) of the base member in the area A by detecting a direction of displacement of the second end 16b of the third linear member <NUM> with respect to the second end 17b of the fourth linear member <NUM>.

In addition, when the base member <NUM> is curved in the area A, the amount of displacement of the second end 16b of the third linear member <NUM> with respect to the second end 17b of the fourth linear member <NUM> depends on a degree of the curvature of the area A (in other words, an angle of a direction in which the center axis X of the base member <NUM> at the fixed position P2 extends, with respect to a direction in which the center axis X of the base member <NUM> at the fixed position P1 extends). Thus, the degree of curvature of the base member <NUM> in the area A can be detected by detecting the amount of the displacement of the second end 16b with respect to the second end 17b.

Further, the direction of curvature of the base member <NUM> in the area A can be detected three-dimensionally by combining the detection result of curvature of the base member <NUM> obtained by means of the third linear member <NUM> and the fourth linear member <NUM>, and the detection result of the curvature obtained by means of the first linear member <NUM> and the second linear member <NUM>.

Next, a second distance displacement sensor <NUM> is described. The second distance displacement sensor <NUM> detects change in a relative position between the second ends 16b, 17b of the third linear member <NUM> and the fourth linear member <NUM>. The second distance displacement sensor <NUM> includes a third sensor 18a and a fourth sensor 18b, and is capable of detecting change in a relative position between the third sensor 18a and the fourth sensor 18b. The third sensor 18a is fixed to the second end 16b of the third linear member <NUM>, and the second sensor 18b is fixed to the second end 17b of the fourth linear member <NUM>. The second distance displacement sensor <NUM> is electrically connected to the display device <NUM>. When a relative position of the third sensor 18a with respect to the fourth sensor 18b changes, the second distance displacement sensor <NUM> inputs, to the display device <NUM>, a signal corresponding to a direction and the amount of displacement of the third sensor 18a with respect to the fourth sensor 18b.

The display device <NUM> determines the direction and the degree of curvature of the base member <NUM> in the area A based on the signal inputted by the second distance displacement sensor <NUM>, and displays them on a display 9b.

In the illustrated example, the display device <NUM> displays the curvature direction detected by means of the second distance displacement sensor <NUM> as "RIGHT", "MID" or "LEFT". Specifically, when the base member <NUM> is not curved in the area A as shown in <FIG>, <FIG> and <FIG>, the display device <NUM> indicates the curvature direction as "MID". When the base member <NUM> is curved leftward in the area A as shown in <FIG>, the display device <NUM> indicates the curvature direction as "LEFT". When the base member <NUM> is curved rightward in the area A as shown in <FIG>, the display device <NUM> indicates the curvature direction as "RIGHT".

In addition, in the illustrated example, the display device <NUM> displays the curvature degree detected by means of the second distance displacement sensor <NUM> as "LARGE" or "SMALL". Specifically, when the amount of displacement of the third sensor 18a with respect to the fourth sensor 18b (thus the amount of displacement of the second end 16b of the third linear member <NUM> with respect to the second end 17b of the fourth linear member <NUM>) is zero (this is the cases of <FIG>, <FIG> and <FIG>), the display device <NUM> does not display the curvature degree. When the amount of displacement of the third sensor 18a with respect to the fourth sensor 18b is greater than <NUM> and less than a predetermined value, the display device <NUM> indicates the curvature degree as "SMALL". When the amount of displacement of the third sensor 18a with respect to the fourth sensor 18b is equal to or greater than the predetermined value, the display device <NUM> indicates the curvature degree as "LARGE".

Next, a curvature detection system <NUM> according to a third embodiment is described with reference to <FIG>.

An example shown in <FIG> differs from the curvature detection system <NUM> shown in <FIG> in that a base member with a curvature detection function <NUM> further has a fifth linear member <NUM> that extends adjacently to a first linear member <NUM> and a second linear member <NUM> in a longitudinal direction LD, and that a distance displacement sensor <NUM> further has a fifth sensor 8c. Other configurations are substantially the same as those of the curvature detection system <NUM> shown in <FIG>. In the example shown in <FIG>, the same numerals are given to the same parts as those of the first embodiment shown in <FIG>, and detailed description thereof is omitted.

In the example shown in <FIG>, a base member <NUM> further has a fifth lumen 4e which extends adjacently to a first lumen 4a and a second lumen 4b in the longitudinal direction LD. The fifth lumen 4e is formed in a wall <NUM> of the base member <NUM>.

A fifth linear member <NUM> is disposed in the fifth lumen 4e. Since the fifth linear member <NUM> is disposed in the lumen 4e, the risk of damaging the fifth linear member <NUM> is reduced. In addition, since the linear members <NUM>, <NUM>, <NUM> are disposed in the lumens 4a, 4b, 4e separated from one another, the risk of causing the linear members <NUM>, <NUM>, <NUM> to be entangled is reduced.

The fifth linear member <NUM> has a first end 108a and a second end 108b positioned on one side of the first end 108a in the longitudinal direction LD. The first end 108a of the fifth linear member <NUM> is fixed to a third fixed position P3 of the base member <NUM> in the fifth lumen 4e. The rest part of the fifth linear member <NUM>, which includes the second end 108b, is disposed in the fifth lumen 4e so that the rest part is relatively movable with respect to the base member <NUM>, as well as the first linear member <NUM> and the second linear member <NUM>, in the longitudinal direction LD. The third fixed position P3 is located at a position apart from the first fixed position P1 and the second fixed position P2 in the longitudinal direction LD. In the illustrated example, the third fixed position P3 is located on the one side of the second fixed poison P2 in the longitudinal direction LD.

The fifth linear member <NUM> is made of a low-stretch material compared to the base member <NUM> and can be curved along the base member <NUM> when it is curved. Similarly to the first linear member <NUM> and the second linear member <NUM>, the fifth linear member <NUM> can be made of various materials, such as metal, resin, etc., depending on an application of the base member with the curvature detection function <NUM>. The fifth linear member <NUM> is preferably made of the same material as that of the first linear member <NUM> and the second linear member <NUM>.

In the illustrated example, a length of the fifth linear member <NUM> is determined in such a manner that, as shown in <FIG>, the second end 108b of the fifth linear member <NUM> is located at the same position as the second end 6b of the first linear member <NUM> and the second end 7b of the second linear member <NUM> in the longitudinal direction LD, with the base member <NUM> not curved at any position in the longitudinal direction LD. However, as described later, the present invention is not limited to this example, as long as it is possible to detect change in a relative position between the second end 6b of the second linear member <NUM> and the second end 108b of the fifth linear member <NUM>.

The base member with the curvature detection function <NUM> as structured above can detect curvature of the base member <NUM> between the first fixed position P1 and the second fixed position P2, based on change in a relative position between the second ends 6b, 7b of the first linear member <NUM> and the second linear member <NUM>. Further, the base member with the curvature detection function <NUM> can detect curvature of the base member <NUM> in an area B1 between the second fixed position P2 and the third fixed position P3, based on change in a relative position between the second ends 7b, 108b of the second linear member <NUM> and the fifth linear member <NUM>.

Next, the distance displacement sensor <NUM> in the third embodiment is described. As described above, the distance displacement sensor <NUM> in this embodiment has the fifth sensor 8c in addition to a first sensor 8a and a second sensor 8b. The fifth sensor 8c is fixed to the second end 108b of the fifth linear member <NUM>. The distance displacement sensor <NUM> in this embodiment is capable of detecting change in a relative position between the second sensor 8b and the fifth sensor 8c, in addition to change in a relative position between the first sensor 8a and the second sensor 8b. When a relative position of the first sensor 8a with respect to the second sensor 8b changes, the distance displacement sensor <NUM> in this embodiment inputs, to a display device <NUM>, a signal corresponding to a direction and the amount of displacement of the first sensor 8a with respect to the second sensor 8b. Further, when a relative position of the second sensor 8b with respect to the fifth sensor 8c changes, the distance displacement sensor <NUM> in this embodiment inputs, to the display device <NUM>, a signal corresponding to a direction and the amount of displacement of the second sensor 8b with respect to the fifth sensor 8c.

The display device <NUM> determines the directions and the degrees of curvature of the base member <NUM> in the area A and the area B1 based on the signals inputted by the distance displacement sensor <NUM>, and displays them on a display 9a.

Next, an example of application of the aforementioned curvature detection system to a balloon catheter is described. A balloon catheter to which the curvature detection system in the second embodiment is applied is particularly described herein. <FIG> is a view showing an entire structure of the catheter system including the balloon catheter.

A balloon catheter system <NUM> shown in <FIG> has a balloon catheter <NUM>, and a heating device <NUM>, a supply device <NUM> and an agitation device <NUM> which are connected to the balloon catheter <NUM>. The balloon catheter <NUM> has a catheter body <NUM> having a longitudinal direction LD, and a handle <NUM> connected to a proximal end of the catheter body <NUM>.

As shown in <FIG>, the catheter body <NUM> in this application example has a balloon <NUM>, an outer cylinder shaft <NUM> connected to a proximal end 25b of the balloon <NUM>, an inner cylinder shaft <NUM> connected to a distal end 25a of the balloon <NUM>, and a heating member <NUM> disposed in the balloon <NUM>. The inner cylinder shaft <NUM> extends inside the outer cylinder shaft <NUM> and into the balloon <NUM>. A liquid delivery path LP in communication with an inside of the balloon <NUM> is formed between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM>. The heating member <NUM> is for heating a liquid in the balloon <NUM>.

The longitudinal direction LD of the catheter body <NUM> is specified as a direction along which center axes 30X, 35X of the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> extending from the outer cylinder shaft <NUM> extend. In this specification, the term "distal" side used for respective components of the balloon catheter <NUM> and the catheter body <NUM> means a side distant from an operator (surgeon) operating the handle <NUM> and the balloon catheter <NUM> along the longitudinal direction LD of the catheter body <NUM>, in other words, a distant side. In addition, the term "proximal" side used for respective components of the balloon catheter <NUM> and the catheter body <NUM> means a side close to the operator (surgeon) operating the handle <NUM> and the balloon catheter <NUM> along the longitudinal direction LD of the catheter body <NUM>, in other words, a near side.

The balloon catheter <NUM> is further described in detail below. The catheter body <NUM> of the balloon catheter <NUM> is first described in detail. As described above, the catheter body <NUM> of the balloon catheter according to this embodiment has the balloon <NUM>, the outer cylinder shaft <NUM>, the inner cylinder shaft <NUM>, and the heating member <NUM>. Further, the catheter body <NUM> in this embodiment has a temperature sensor <NUM> disposed in an inside space of the balloon <NUM>.

The outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> both have a tubular shape, typically a cylindrical shape. Thus, the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> respectively form lumens as inside spaces. A not-shown guide wire, for example, is inserted thorough the lumen formed by the inner cylinder shaft <NUM>. The inner cylinder shaft <NUM> is inserted through the lumen formed by the outer cylinder shaft <NUM>. Namely, the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> form a dual shaft structure. An internal diameter of the outer cylinder shaft <NUM> is larger than an external diameter of the inner cylinder shaft <NUM>. Thus, a lumen remains between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM>. The lumen between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> forms the liquid delivery path LP. As shown in <FIG>, the liquid delivery path LP is in communication with the inside of the balloon <NUM>. The liquid delivery path LP extends into the handle <NUM>.

Lengths of the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> are preferably between <NUM> or more and <NUM> or less, and more preferably between <NUM> or more and <NUM> or less. The outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> are preferably made of a flexible material with excellent antithrombotic properties. The flexible material with excellent antithrombotic properties may include, for example, fluoropolymers, polyamides, polyurethane-based polymers, or polyimides, but is not limited thereto. The outer cylinder shaft <NUM> is preferably manufactured by stacking layers of different flexible materials, in order to have both sliding facility to the inner cylinder shaft <NUM> and adhesion or heat weldability to the balloon <NUM>.

The external diameter of the outer cylinder shaft <NUM> is preferably between <NUM> or more and <NUM> or less. The internal diameter of the outer cylinder shaft <NUM> is preferably between <NUM> or more and <NUM> or less. The external diameter of the inner cylinder shaft <NUM> is preferably between <NUM> or more and <NUM> or less. The internal diameter of the inner cylinder shaft <NUM> is preferably between <NUM> or more and <NUM> or less.

The balloon <NUM> is connected to the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM>. The balloon <NUM> is formed so as to be inflatable when it is filled with a liquid and deflatable when the liquid is discharged therefrom. The balloon <NUM> is preferably shaped to fit a target site to be treated (e.g., blood vessel). As an example, the balloon <NUM> adapted for a pulmonary vein junction of a left atrium may have a spherical shape having a diameter between <NUM> or more and <NUM> or less. The spherical shape here includes a true spherical shape, a prolate shape, and a prolate spheroid shape. It also includes a substantially spherical shape.

A thickness of the balloon <NUM> is preferably between <NUM> or more and <NUM> or less. A material of the balloon <NUM> is preferably an elastic material with excellent antithrombotic properties such as a polyurethane-based polymer material. The polyurethane-based polymer material applicable to the balloon <NUM> may be, for example, thermoplastic polyether urethane, polyether polyurethane urea, fluorinated polyether urethane urea, polyether polyurethane urea resin, or polyether polyurethane urea amide.

In the illustrated catheter body <NUM>, as shown in <FIG> and <FIG>, the distal end (distant end) 25a of the balloon <NUM> is fixed to a distal end (distant end) 35a of the inner cylinder shaft <NUM>. The proximal end (near end) 25b of the balloon <NUM> is fixed to a distal end (distant end) 30a of the outer cylinder shaft <NUM>. In the illustrated example, the distal end 30a of the outer cylinder shaft <NUM> does not extend into the balloon <NUM>. However, not limited to the illustrated example, the distal end 30a of the outer cylinder shaft <NUM> may extend into the balloon <NUM>. The balloon <NUM> may be connected to the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> by adhesion or heat welding.

By the relative movement between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> in the longitudinal direction LD, the balloon <NUM> connected to the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> deforms. In the illustrated example, the relative movement between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> allows a dimension of the balloon <NUM> to be adjusted in the longitudinal direction LD. As shown in <FIG>, when the inner cylinder shaft <NUM> is relatively moved with respect to the outer cylinder shaft <NUM> to the distal side in the longitudinal direction LD, the balloon <NUM> is stretched in the longitudinal direction LD and is strained. In the illustrated example, the movement range of the inner cylinder shaft <NUM> with respect to the outer cylinder shaft <NUM> to the distal side in the longitudinal direction LD is restricted by the balloon <NUM>. When the inner cylinder shaft <NUM> in the state shown in <FIG> is relatively moved with respect to the outer cylinder shaft <NUM> to the proximal side in the longitudinal direction LD, the balloon <NUM> becomes loosened. By introducing a liquid into the loosened balloon <NUM>, the balloon <NUM> can be inflated as shown in <FIG>. Namely, the relative movement between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> allows the dimension of the balloon <NUM> to be adjusted in the longitudinal direction LD.

Next, the heating member <NUM> is described. The heating member <NUM> is disposed in the balloon <NUM>. The heating member <NUM> is a member for heating a liquid filled in the balloon <NUM>. As an example, a nichrome wire that generates electric resistance heat can be employed as the heating member <NUM>. A coil electrode <NUM> may be employed as another example of the heating member <NUM>, as shown in <FIG> and <FIG>. By means of high-frequency current conduction (high-frequency energization) to the heating member <NUM> as the coil electrode <NUM>, a high-frequency current flows between the coil electrode <NUM> and a counter electrode <NUM> (<FIG>) disposed outside, so that the liquid positioned between the coil electrode <NUM> and the counter electrode <NUM> generates Joule heat. The counter electrode <NUM> is located on the back of a patient, for example.

In the example shown in <FIG> and <FIG>, the coil electrode <NUM> is provided on the inner cylinder shaft <NUM> extending inside the balloon <NUM>. The coil electrode <NUM> may be made by a conductive wire wound around the inner cylinder shaft <NUM>. The coil electrode <NUM> is electrically connected to a wire <NUM> for high-frequency current conduction. The wire <NUM> extends in the liquid delivery path LP, which is a lumen between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM>, to the handle <NUM>. A specific example of the coil electrode <NUM> forming the heating member <NUM> may be a coil electrode that is made as follows. An insulation-coated lead wire used as the wire <NUM> is stripped of its coating. Then, the lead wire is wound around the inner cylinder shaft <NUM> to provide a coil electrode. Since such a coil electrode <NUM> is integrally formed with the wire <NUM>, occurrence of trouble such as disconnection of wire can be effectively minimized.

Diameters of the coil electrode <NUM> and the wire <NUM> are preferably between <NUM> or more and <NUM> or less, and more preferably between <NUM> or more and <NUM> or less. A conductive material forming the coil electrode <NUM> and the wire <NUM> may be, for example, copper, silver, gold, platinum, and alloys thereof. In order to prevent a short circuit, the wire <NUM> is preferably a conductive linear member covered with an insulating film made of fluoropolymer, for example.

Next, the temperature sensor <NUM> is described. The temperature sensor <NUM> is disposed in the inside space of the balloon to acquire information on a temperature of a liquid in the balloon <NUM>. In the illustrated example, the temperature sensor <NUM> has a thermosensitive part <NUM> disposed in the vicinity of the heating member <NUM>. The temperature sensor <NUM> can acquire information of a temperature of a liquid in the vicinity of the heating member <NUM>. The liquid around the heating member <NUM> can be heated to a proper temperature by applying electric energy to the heating member <NUM> based on the information acquired by the temperature sensor <NUM>.

A thermocouple or thermistor can be used as the temperature sensor <NUM>. Information on a temperature acquired by the temperature sensor <NUM> is, for example, an electric potential that can be acquired from a thermocouple, or a resistance value that can be acquired from a thermistor.

As shown in <FIG> and <FIG>, the temperature sensor <NUM> typically has the thermosensitive part <NUM>, and a lead wire <NUM> electrically connected to the thermosensitive part <NUM>. When the temperature sensor <NUM> comprises a thermocouple, a part where different metals are connected in the thermocouple serves as the thermosensitive part <NUM>. When the temperature sensor <NUM> comprises a thermistor, a ceramic element in the thermistor serves as the thermosensitive part <NUM>. The lead wire <NUM> extends inside the liquid delivery path LP, which is the lumen between the outer cylinder shaft <NUM> and the inner cylinder shaft <NUM>, to the handle <NUM>.

A diameter of the lead wire <NUM> is preferably between <NUM> or more and <NUM> or less, and more preferably between <NUM> or more and <NUM> or less. The temperature sensor <NUM> comprising a thermocouple may be formed by using constantan for the lead wire <NUM> and copper for the wire <NUM> for high-frequency current conduction, and by joining them. In this example, the thermosensitive part <NUM> formed by joining the lead wire <NUM> and the wire <NUM> can function as a thermocouple. In order to prevent a short circuit between the lead wire <NUM> and the wire <NUM>, the lead wire <NUM> is preferably provided with an electrically insulating cover made of fluoropolymer, enamel, etc..

Next, the handle <NUM> connected to the aforementioned catheter body <NUM> from the proximal side is described. The handle <NUM> is a part grasped by an operator (surgeon) during the use of the balloon catheter system <NUM>. Thus, the handle <NUM> preferably has a design that allows an operator to easily grasp and operate the handle <NUM> with his/her hand. The handle <NUM> is preferably made of a material having excellent chemical resistance, such as polycarbonate or ABS resin.

The handle <NUM> shown in <FIG> has a first handle part <NUM> and a second handle part <NUM> that are slidable to each other. The first handle part (front handle part) <NUM> is connected to the outer cylinder shaft <NUM> of the catheter body <NUM>. The second handle part (rear handle part) <NUM> is connected to the inner cylinder shaft <NUM> of the catheter body <NUM>. By relatively moving the second handle part <NUM> with respect to the first handle part <NUM>, the inner cylinder shaft <NUM> can be relatively moved with respect to the outer cylinder shaft <NUM>.

As shown in <FIG>, the handle <NUM> also functions as a part that connects devices included in the balloon catheter system <NUM>, and the balloon catheter <NUM>.

A connector <NUM> extends from the second handle part <NUM>. The connector <NUM> electrically connects the wire <NUM> and the lead wire <NUM> to the external heating device <NUM>. The connector <NUM> extends from one branch 52a of a plurality of branches 52a, 52b, 52c of the second handle part <NUM>.

The connector <NUM> preferably has a structure capable of effectively preventing improper connection. In addition, the connector <NUM> preferably has excellent waterproofness. The structure of the connector <NUM> can be decided in consideration of surgeon's convenience and design matter. Similarly to the handle <NUM>, the connector <NUM> is preferably made of a material forming having excellent chemical resistance such as polycarbonate or ABS resin.

The connector <NUM> may have therein a highly conductive metal pin. The wire <NUM> and the lead wire <NUM> are connected to this highly conductive metal pin so as to be electrically connectable to the heating device <NUM> serving as means for supplying high-frequency power. Note that the lead wire <NUM> may be electrically connected to a device other than the heating device <NUM> serving as means for supplying high-frequency power, such as a temperature indicator. A material of the highly conductive metal pin included in the connector <NUM> may be of any type, as long as it is a metal having high conductivity. A material of the high conductive metal pin included in the connector <NUM> may be, for example, copper, silver, gold, platinum, and alloys thereof. In addition, an outside of the highly conductive metal pin is preferably protected by a material having electrically insulating properties and chemical resistance. An electrically insulating and chemically resistant material may be, for example, polysulfone, polyurethane-based polymers, polypropylene, or polyvinyl chloride.

The second handle part <NUM> has branches 52b and 52c other than the branch 52a to which the connector <NUM> is connected. These branches 52b and 52c serve as a part through which a liquid is supplied to the lumen as an inside space of the inner cylinder shaft <NUM>, and a part from which a guide wire inserted through the lumen of the inner cylinder shaft <NUM> extends. During a cardiac ablation therapy, a saline solution the amount of which is as small as about <NUM>/hour is generally injected into a patient's body through the lumen of the inner cylinder shaft <NUM>. The injection of saline solution effectively prevents backflow of blood into the lumen of the inner cylinder shaft <NUM>.

In addition, as shown in <FIG>, an extension tube <NUM> extends from the first handle part <NUM>. The extension tube <NUM> communicates the liquid delivery path LP of the catheter body <NUM> with an external supply device <NUM> or the external agitation device <NUM>. The extension tube <NUM> extends from the branch 51a provided on the first handle part <NUM>. The extension tube <NUM> is connected to the supply device <NUM> and the agitation device <NUM> via a valve <NUM>. In the illustrated example, whether the supply device <NUM> or the agitation device <NUM> is communicated with the liquid delivery path LP can be selected by operating the valve <NUM>. A three-way stopcock may be used as the valve <NUM>.

Next, devices constituting the balloon catheter system <NUM> together with the aforementioned balloon catheter <NUM>, to be specific, the heating device <NUM>, the supply device <NUM> and the agitation device <NUM>, are described.

The illustrated heating device <NUM> is electrically connected to the coil electrode <NUM> via a connection cable 56a and the wire <NUM>. High-frequency power generated by the heating device <NUM> is supplied to the coil electrode <NUM> through the connection cable 56a and the wire <NUM>. The heating device <NUM> has a high-frequency current conduction controller <NUM> that controls high-frequency current conduction to the coil electrode <NUM>. In the illustrated example, the high-frequency current conduction controller <NUM> controls the high-frequency current conduction to the coil electrode <NUM> to adjust an output from the heating member <NUM>. The high-frequency current conduction controller <NUM> is electrically connected to the connection cable 56a and the lead wire <NUM> to be capable of controlling the high-frequency current conduction to the coil electrode <NUM> based on information on a temperature of a liquid in the balloon <NUM>, which is acquired by the temperature sensor <NUM>.

The heating device <NUM> is constituted by a hardware such as a CPU, for example. One or more of the high-frequency current conduction controller <NUM> and another component included in the heating device <NUM> may be constituted by a separate hardware. At least a part of the heating device <NUM> may be constituted by a software. A part of the heating device <NUM> may be physically separated from the other part of the heating device <NUM>. A component of the heating device <NUM> may be able to cooperate with another component thereof by communication through a network. A component of the heating device <NUM> may be on a device, such as a server or database in the cloud, which can communicate with another component of the heating device <NUM> through an external network.

Next, the supply device <NUM> is described. The supply device <NUM> supplies a liquid into the liquid delivery path LP. The supply device <NUM> can inflate the balloon <NUM>, as shown in <FIG>, by supplying a liquid to the balloon <NUM> through the liquid delivery path LP. Also, the supply device <NUM> can deflate the balloon <NUM> by discharging the liquid from the balloon <NUM> through the liquid delivery path LP. A syringe can be used as the supply device <NUM> as illustrated. A pump or the like can also be used as the supply device <NUM>. The liquid to be supplied to the liquid delivery path LP is preferably a contrast or a contrast diluted with saline in order that the balloon <NUM> inflated with the liquid can be seen in a radiographic image.

Next, the agitation device <NUM> is described. The agitation device <NUM> is provided for agitating a liquid in the balloon <NUM>. By agitating the liquid in the balloon <NUM>, the liquid heated by the heating member <NUM> can be diffused to equalize a temperature of the liquid in the balloon <NUM>. As a result, a surface temperature of the balloon <NUM> can be adjusted. The agitation device <NUM> repeats supply of liquid to the liquid delivery path LP and discharge of liquid from the liquid delivery path LP. Thus, supply of liquid from the liquid delivery path LP into the balloon <NUM> and discharge of liquid from inside the balloon <NUM> to the liquid delivery path LP are repeated, so that the liquid in the balloon <NUM> is agitated. A pump selected from the group consisting of a roller pump, a diaphragm pump, a bellows pump, a vane pump, a centrifugal pump, and a pump comprising a piston and a cylinder in combination, can be employed as the agitation device <NUM>.

The amount of liquid to be supplied to the liquid delivery path LP and the amount of liquid to be discharged from the liquid deliver path LP may be a predetermined amount (e.g., between <NUM> or more and <NUM> or less). Supply of liquid to the liquid delivery path LP and discharge of liquid from the liquid delivery path LP may be repeated at a regular cycle (e.g., between once or more and three times or less per second). The amount of liquid to be supplied to the liquid delivery path LP and the amount of liquid to be discharged from the liquid deliver path LP may be adjusted by a control signal from a not-shown agitation-device controller or by a direct input from an operator. Similarly, a cycle at which a liquid is supplied to the liquid delivery path LP and a liquid is discharged from the liquid delivery path LP may be adjusted by a control signal from the not-shown agitation-device controller or by a direct input from an operator.

In order to adjust a surface temperature of the balloon <NUM> to an ideal temperature, it is necessary to efficiently diffuse a liquid heated by the heating member <NUM> in the balloon <NUM>. In order to diffuse the heated liquid efficiently, most (or all) of the liquid flowing from the liquid delivery path LP into the balloon <NUM> is desired to be directed to the heating member <NUM>, during the supply of liquid by the agitation device <NUM> from the liquid delivery path LP into the balloon <NUM>. However, if a pressing force is applied to the balloon <NUM>, for example, so that the inner cylinder shaft <NUM> is curved during an operation, there is a possibility that a direction along which the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM> are aligned is significantly displaced from an ejection direction along which the liquid is ejected from the distal end 30a of the outer cylinder shaft <NUM> (a direction along the center axis 30X of the outer cylinder shaft <NUM> at the distal end 30a). When the liquid is supplied into the balloon <NUM> under this state, most or all of the liquid flowing from the liquid delivery path LP into the balloon <NUM> is not directed to the heating member <NUM>, so that most or all of the heated liquid close to the heating member <NUM> cannot be diffused. As a result, a surface temperature of the balloon <NUM> cannot be increased as desired. In addition, since a temperature of the liquid in the vicinity of the temperature sensor <NUM> is maintained to be high, electric energy is not sufficiently supplied from the heating device <NUM> to the heating member <NUM> although a surface temperature of the balloon <NUM> has not risen to a desired temperature. Also, in this case, there is a possibility that a surface temperature of the balloon <NUM> cannot be raised as desired. Namely, unless the liquid heated by the heating member <NUM> can be efficiently diffused, it is difficult to adjust a surface temperature of the balloon <NUM> to an ideal temperature.

<FIG> shows the balloon catheter <NUM>, with the balloon <NUM> being perpendicularly pressed against an opening surface of an ostia venarum pulmonalium 99a of a pseudo-living body <NUM>. In the example shown in <FIG>, a direction along which the force is applied to the balloon <NUM> is a direction along the center axis 30X at the distal end 30a of the outer cylinder shaft <NUM>. The inner cylinder shaft <NUM> is not curved between the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM>. Thus, the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM> are aligned along the ejection direction (the direction along the center axis 30X of the outer cylinder shaft <NUM> at the distal end 30a) along which the liquid is ejected from the distal end 30a of the outer cylinder shaft <NUM>.

<FIG> shows the balloon catheter <NUM>, with the balloon <NUM> being pressed against the opening surface of the ostia venarum pulmonalium 99a of the pseudo-living body <NUM> at an angle between <NUM> degrees and <NUM> degrees. In the example shown in <FIG>, a direction along which the force is applied to the balloon <NUM> intersects the direction along the center axis 30X at the distal end 30a of the outer cylinder shaft <NUM>. The inner cylinder shaft <NUM> is largely curved between the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM>. Thus, the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM> are not aligned along the ejection direction, along which the liquid is ejected from the distal end 30a of the outer cylinder shaft <NUM>.

In <FIG> and <FIG>, a flow of the liquid (agitation flow) ejected from the distal end 30a of the outer cylinder shaft <NUM> into the balloon <NUM> is indicated by arrows.

As can be understood from <FIG>, when the inner cylinder shaft <NUM> is not curved between the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM>, a large part of the liquid ejected from the liquid delivery path LP into the balloon <NUM> surrounds the inner cylinder shaft <NUM> moving toward the heating member <NUM>. Then, the liquid surrounds the heating member <NUM> anew diffusing a large part of the heated liquid in the vicinity of the heating member <NUM>. The diffused liquid moves toward the surface of the balloon <NUM> to heat the surface of the balloon <NUM>. The liquid which has surrounded the heating member <NUM> anew is heated by the heating member <NUM>. In the example shown in <FIG>, the liquid heated by the heating member <NUM> is evenly diffused in the balloon <NUM>, whereby the inside of the balloon <NUM> and the surface of the balloon <NUM>, i.e., areas indicated by h, i, j, k in <FIG> have substantially the same temperature as a whole. In addition, since the liquid heated by the heating member <NUM> is efficiently diffused, it is easy to adjust a surface temperature of the balloon <NUM> to a desired temperature by adjusting supply of electric energy to the heating member <NUM>. This can significantly improve an ablation therapy effectiveness.

On the other hand, as can be understood from <FIG>, when the inner cylinder shaft <NUM> is largely curved between the distal end 30a of the outer cylinder shaft <NUM> and the heating member <NUM>, the liquid ejected from the liquid delivery path LP into the balloon <NUM> is deflected from the heating member <NUM> and moves toward the surface of the balloon <NUM> without being heated by the heating member <NUM>. Thus, the liquid heated by the heating member <NUM> cannot be efficiently diffused. Specifically, most (or all) of the liquid heated by the heating member <NUM> cannot be diffused by the agitation flow. Alternatively, the heated liquid cannot be evenly diffused in the balloon <NUM>. As a result, conduction of heat generated by the heating member <NUM> relies on thermal radiation in the balloon <NUM>, which makes the temperature of the entire balloon <NUM> low and unstable. Alternatively, the surface temperature of the balloon <NUM> becomes uneven. For example, when the liquid flows in the balloon <NUM> as shown in <FIG>, temperatures of surface areas indicated by i and h may be lower than those of areas indicated by j and k. This makes it difficult to adjust a surface temperature of the balloon <NUM> to a desired temperature. As a result, an ablation therapy canton be performed as desired.

In general, a balloon catheter is operated observing a radioscopic image of a distant end of the balloon catheter. The radioscopic image is a two-dimensional image. Thus, it is difficult to perceive curvature of the distant end of the balloon catheter based on the radioscopic image. Even when curvature is perceived, it is difficult to find out a direction and/or a degree of the curvature. In order to make it possible to perceive a direction and a degree of curvature of a balloon catheter during an operation on a constant basis, it is generally necessary to obtain radioscopic images as video images. However, this solution is problematic in that it increases the amount of X-ray exposure.

In consideration of these issues, as shown in <FIG>, the balloon catheter <NUM> in this embodiment includes, as the inner cylinder shaft <NUM>, the base member with the curvature detection function <NUM> shown in <FIG>. This enables a surgeon to easily detect a curvature state (curvature direction and curvature degree) of the inner cylinder shaft <NUM> on a constant basis. <FIG> shows only the first linear member <NUM> and the second linear member <NUM> among the linear members <NUM>, <NUM>, <NUM>, <NUM>. In addition, <FIG> omits illustration of lumens 4a, 4b, 4c, 4d.

In the illustrated example, the one-side end of the base member <NUM> of the base member with the curvature detection function <NUM> is defined as the proximal end of the inner cylinder shaft <NUM>, and the other-side end of the base member <NUM> is defined as the distal end of the inner cylinder shaft <NUM>. The first fixed position P1 is located at a position overlapping the proximal end 40b of the heating member <NUM>, when viewed in a radial direction of a circle centered on the center axis X of the base member <NUM> (or center axis 35X of the inner cylinder shaft <NUM>). The second fixed position P2 is located at a position overlapping the distal end 35a of the outer cylinder shaft <NUM> with the balloon <NUM> being inflated, when viewed in a radial direction of a circle centered on the center axis X of the base member <NUM>. Such an inner cylinder shaft <NUM> makes it possible to detect curvature of the inner cylinder shaft <NUM> between the heating member <NUM> and the distal end 30a of the outer cylinder shaft <NUM> on a constant basis, during cautery of a target site with the balloon <NUM> being inflated. Then, a posture of the distant end of the inner cylinder shaft <NUM> can be corrected by operating the balloon catheter <NUM> based on the detected curvature state (curvature direction and curvature degree) of the inner cylinder shaft <NUM>.

In particular, in the illustrated example, the balloon catheter system <NUM> includes the distance displacement sensors <NUM>, <NUM> connected to the linear members <NUM>, <NUM>, <NUM>, <NUM> of the inner cylinder shaft <NUM>, and the display device <NUM> that receives a signal inputted by the distance displacement sensors <NUM>, <NUM>. Thus, a surgeon can see the displays 9a, 9b of the display device <NUM> to find out the curvature state of the inner cylinder shaft <NUM>. <FIG> only shows the distance displacement sensor <NUM> among the distance displacement sensors <NUM>, <NUM> of the inner cylinder shaft <NUM>. The distance displacement sensors <NUM>, <NUM> of the inner cylinder shaft <NUM> are electrically connected to the display device <NUM> via the connector <NUM>.

Further, in the illustrated example, as shown in <FIG>, the base member <NUM> with the curvature detection function <NUM> shown in <FIG> is used as the outer cylinder shaft <NUM>. This enables a surgeon to easily find out a curvature state (curvature direction and curvature degree) of the outer cylinder shaft <NUM> on a constant basis.

In the illustrated example, the one-side end of the base member <NUM> of the base member with the curvature detection function <NUM> is defined as the proximal end of the outer cylinder shaft <NUM>, and the other-side end of the base member <NUM> is defined as the distal end of the outer cylinder shaft <NUM>. The first fixed position P1 of the outer cylinder shaft <NUM> is located at the distal end of the outer cylinder shaft <NUM>. The second fixed position P2 of the outer cylinder shaft <NUM> is located on the proximal end side of the distal end 30a of the outer cylinder shaft <NUM>. A distance between the first fixed position P1 and the second fixed position P2 in the outer cylinder shaft <NUM> is, for example, between <NUM> or more and <NUM> or less. Such an outer cylinder shaft <NUM> makes it possible to detect curvature of the outer cylinder shaft <NUM> in the vicinity of the distal end 30a on a constant basis, to find out, based on the detection, a pressing direction of the balloon <NUM> against a target site on a constant basis. Thus, a posture of the distant end of the outer cylinder shaft <NUM> and a pressing direction of the balloon <NUM> against a target site can be corrected by operating the balloon catheter <NUM> based on the detection of curvature state (curvature direction and curvature degree) of the outer cylinder shaft <NUM>.

In particular, in the illustrated example, the balloon catheter system <NUM> includes the distance displacement sensors <NUM>, <NUM> connected to the linear members <NUM>, <NUM>, <NUM>, <NUM> of the outer cylinder shaft <NUM>, and the display device <NUM> that receives a signal inputted by the distance displacement sensors <NUM>, <NUM>. Thus, a surgeon can see the displays 9a, 9b of the display device <NUM> to find out the curvature state of the outer cylinder shaft <NUM>. <FIG> only shows the distance displacement sensor <NUM> among the distance displacement sensors <NUM>, <NUM> of the outer cylinder shaft <NUM>. The distance displacement sensors <NUM>, <NUM> of the outer cylinder shaft <NUM> are electrically connected to the display device <NUM> via the connector <NUM>.

When the base member with the curvature detection function <NUM> is used as the inner cylinder shaft <NUM> and/or the outer cylinder shaft <NUM> of the balloon catheter <NUM>, a diameter of the linear member <NUM>, <NUM>, <NUM>, <NUM> is preferably between <NUM> or more and <NUM> or less. Further, in this case, a metal wire made of a corrosion-resistant metal such as SUS <NUM> or nickel, or a resin monofilament with low-stretch and high strength can be used for the linear member <NUM>, <NUM>, <NUM>, <NUM>.

Next, an example of the use of the balloon catheter system <NUM> as structured above is described.

First, the inner cylinder shaft <NUM> is relatively moved with respect to the outer cylinder shaft <NUM> to the distal side (distant side) in the longitudinal direction LD, so that the balloon <NUM> is stretched as shown in <FIG>. The outer cylinder shaft <NUM> and the inner cylinder shaft <NUM> can be relatively moved by operating the first handle part <NUM> and the second handle part <NUM> of the handle <NUM>. Then, the catheter body <NUM> with the balloon <NUM> stretched is inserted into the patient's body. When the catheter body <NUM> is inserted into the patient's body, the balloon <NUM> is not filled with a liquid.

Next, the distal end of the catheter body <NUM> is guided close to a target site (affected area), and then the inner cylinder shaft <NUM> is relatively moved with respect to the outer cylinder shaft <NUM> to the proximal side (near side) in the longitudinal direction LD, so that the balloon <NUM> is loosened. Then, the valve <NUM> is operated to communicate the supply device <NUM> with the liquid delivery path LP of the catheter body <NUM>. Thereafter, the supply device <NUM> is operated to let a liquid to flow into the liquid delivery path LP, so that the balloon <NUM> is inflated with the liquid as shown in <FIG>.

Then, the valve <NUM> is operated to shut off the supply device <NUM> from the liquid delivery path LP, and to communicate the agitation device <NUM> with the liquid delivery path LP. The agitation device <NUM> is controlled by a control signal from the not-shown agitation-device controller, in such a manner that the agitation device <NUM> repeats supply of a predetermined amount of liquid to the liquid delivery path LP and discharge of a predetermined amount of liquid from the liquid delivery path LP at a regular cycle. This results in repeated ejection of the predetermined amount of liquid from the liquid delivery path LP into the balloon <NUM> and suction of the predetermined amount of liquid from inside the balloon <NUM> to the liquid delivery path LP at a regular cycle. Thus, the liquid in the balloon <NUM> is agitated.

Also, a liquid temperature in the balloon <NUM> is adjusted by controlling the heating member <NUM> by means of the high-frequency current conduction controller <NUM> of the heating device <NUM>. Specifically, by means of the heating device <NUM>, a high-frequency voltage is applied between the coil electrode <NUM> of the heating member <NUM> and the counter electrode <NUM> disposed outside the patient's body. As a result, a high-frequency current flows between the coil electrode <NUM> and the counter electrode <NUM>.

The liquid in the balloon <NUM> is agitated while being heated as described above. Then, the balloon containing the heated liquid is pressed against the target site to ablate the target site.

During the ablation, the catheter body <NUM> is operated to correct a pressing direction of the balloon <NUM> against the target site, observing a curvature state close to the distal end 30a of the outer cylinder shaft <NUM>, which is displayed on the displays 9a, 9b of the display device <NUM>. In addition, observing a curvature state of the inner cylinder shaft <NUM> between the coil electrode <NUM> and the distal end 30a of the outer cylinder shaft <NUM> displayed on the displays 9a, 9b of the display device <NUM>, the catheter body <NUM> is operated to adjust a direction along which the coil electrode <NUM> and the distal end 30a of the outer cylinder shaft <NUM> are aligned so that the direction of the alignment matches a direction along which the center axis 30X of the outer cylinder shaft <NUM> in the distal end 30a of the outer cylinder shaft <NUM> extends.

The use of such a balloon catheter <NUM> allows a surgeon to easily press the balloon <NUM> against a target site in a proper direction. In addition, it is easy to correct a posture of the distant end of the inner cylinder shaft <NUM> to effectively agitate a liquid in the balloon <NUM>. Thus, it is easy to adjust a surface temperature of the balloon, which is one of the most important factors in the ablation therapy, to an ideal temperature. This can significantly improve the ablation therapy effect.

Upon completion of the ablation to the target site, energy supply to the heating member <NUM> is stopped. In addition, the valve <NUM> is operated so that the supply device <NUM> is communicated with the liquid delivery path LP of the catheter body <NUM> through the handle <NUM>, and that the agitation device <NUM> is shut off from the liquid delivery path LP. Then, the liquid is discharged by means of the supply device <NUM> from the liquid delivery path LP to deflate the balloon <NUM>. Then, the second handle part <NUM> is operated to stretch the deflated balloon <NUM> as shown in <FIG>. After that, the catheter body <NUM> with the balloon <NUM> stretched is pulled out from the patient's body. In this manner, the procedure using the balloon catheter system <NUM> is completed.

The base member with the curvature detection function <NUM>, <NUM>, <NUM>, the curvature detection system <NUM>, <NUM>, <NUM>, and the balloon catheter system <NUM> to which the curvature detection system <NUM>, <NUM>, <NUM> is applied have been described above, with reference to <FIG>, <FIG> and <FIG>. However, the base member with the curvature detection function <NUM>, <NUM>, <NUM>, the curvature detection system <NUM>, <NUM>, <NUM>, and the balloon catheter system <NUM> are not limited to the structures described above. The base member with the curvature detection function <NUM>, <NUM>, <NUM>, the curvature detection system <NUM>, <NUM>, <NUM>, and the balloon catheter system <NUM> shown in <FIG> can be variously changed in structure.

For example, in the examples shown in <FIG>, the first linear member <NUM> and the second linear member <NUM> are disposed in the separate lumens 4a, 4b, but they may be disposed in the same lumen. The first linear member <NUM> and the second linear member <NUM> may not be disposed in the lumens 4a, 4b, but may be disposed on a surface of the base member <NUM>. In addition, in the examples shown in <FIG> and <FIG>, the third linear member <NUM> and the fourth linear member <NUM> are disposed in the separate lumens 4c, 4d, but they may be disposed in the same lumen. The third linear member <NUM> and the fourth linear member <NUM> may not be disposed in the lumens 4c, 4d, but may be disposed on the surface of the base member <NUM>. In the example shown in <FIG>, the fifth linear member <NUM> is disposed in the lumen 4e separated from the lumens 4a, 4b of the first linear member <NUM> and the second linear member <NUM>, but the linear members <NUM>, <NUM>, <NUM> may be disposed in the same lumen. The linear members <NUM>, <NUM>, <NUM> may not be disposed in the lumens 4a, 4b, 4e, but may be disposed on the surface of the base member <NUM>.

In the examples shown in <FIG> and <FIG>, the display device <NUM> displays the curvature direction of the base member <NUM> as two pieces of information, i.e., the vertical direction and the horizontal direction, but the present invention is not limited thereto. The display device <NUM> may computes a signal inputted by the distance displacement sensor <NUM> and a signal inputted by the second distance displacement sensor <NUM>, and may display one curvature direction in which the curvature direction of the base member in the vertical direction and the curvature direction thereof in the horizontal direction are combined in one. This allows a surgeon to more easily understand the curvature direction of the base member <NUM>.

In the examples shown in <FIG>, the display device <NUM> displays the curvature direction and the curvature degree of the base member <NUM> by characters, but the present invention is not limited thereto. The display device <NUM> may show the curvature direction by an image, a chart, a vector, etc. In particular, when the curvature direction of the base member <NUM> is shown as one curvature direction in which the curvature direction of the base member in the vertical direction and the curvature direction thereof in the horizontal direction are combined, the display device <NUM> preferably displays the curvature direction by an image, a chart, a vector, etc..

In the examples shown in <FIG>, change in a relative position between the second ends 6b, 7b; 16b, 17b; 6b, 7b, 108b is detected by the distance displacement sensor <NUM>, <NUM>, but the present invention is not limited thereto. For example, change in a relative position between the second ends 6b, 7b; 16b, 17b; 6b, 7b, 108b may be detected by means of a pressure sensor. In this case, change in a relative position between the second ends 6b, 7b; 16b, 17b; 6b, 7b, 108b may be detected by detecting a difference between tensile forces or pressing forces applied by the linear members <NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>, <NUM>. A proximity sensor or the like may be employed as a sensor that detects change in a relative position between the second ends 6b, 7b; 16b, 17b; 6b, 7b, 108b.

Change in a relative position between the second ends 6b, 7b; 16b, 17b may be detected by means of markers provided on the surfaces of the linear member <NUM>, <NUM> and the linear member <NUM>, <NUM>, i.e., by observing change in a relative position between the marker provided on the linear member <NUM>, <NUM> and the marker provided on the linear member <NUM>, <NUM>. One marker may be a distance measuring scale capable of measuring a relative movement distance of the other marker. These markers may be provided on other members fixed to the linear member <NUM>, <NUM> and the linear member <NUM>, <NUM>. Change in a relative position between the second ends 17b, 108b may also be detected by means of markers.

Further, the curvature detection system <NUM>, <NUM>, <NUM> may comprise an alarm which issues a warning that curvature has occurred.

The application of the aforementioned curvature detection system <NUM>, <NUM>, <NUM> and the base member with the curvature detection function <NUM>, <NUM>, <NUM> is not limited to a balloon catheter. The base member with the curvature detection function <NUM>, <NUM>, <NUM> may be applied to a catheter of another type or another medical device such as a medical endoscope. Further, the base member with the curvature detection function <NUM>, <NUM>, <NUM> may be applied to a device other than a medical device, such as an industrial endoscope.

In the aforementioned first to third embodiments, the base member with the curvature detection function <NUM>, <NUM>, <NUM> comprises the base member <NUM> having the longitudinal direction LD, the first linear member <NUM> extending along the longitudinal direction LD, and the second linear member <NUM> extending along the longitudinal direction LD. The first linear member <NUM> is fixed to the base member <NUM> at the first fixed position P1, and is relatively movable with respect to the base member <NUM> in the longitudinal direction LD, on the one side of the first fixed position P1 in the longitudinal direction LD. The second linear member <NUM> is fixed to the base member <NUM> at the second fixed position P2 apart from the first fixed position P1 in the longitudinal direction LD, and is relatively movable with respect to the base member <NUM> in the longitudinal direction LD, on the one side of the second fixed poison P2 in the longitudinal direction LD. The base member with the curvature detection function <NUM>, <NUM>, <NUM> is capable of detecting curvature of the base member <NUM> between the first fixed position P1 and the second fixed position P2 based on change in a relative position between the first linear member <NUM> and the second linear member7.

In the first to third embodiments, the first linear member <NUM> and the second linear member <NUM> are disposed in one or more lumens 4a, 4b provided in the base member <NUM>. This can reduce the risk of damaging the linear members <NUM>, <NUM> and preventing the base member with the curvature detection function <NUM>, <NUM>, <NUM> from detecting curvature of the base member <NUM>.

In the first to third embodiments, the first linear member <NUM> and the second linear member <NUM> are disposed in the separate lumens 4a, 4b. This can reduce the risk of causing the linear members <NUM>, <NUM> to be entangled and preventing the base member with the curvature detection function <NUM>, <NUM>, <NUM> from detecting curvature of the base member <NUM>.

In the first to third embodiments, the base member <NUM> is a cylindrical member having the wall <NUM> delimiting the hollow. Such a shape of the base member <NUM> allows the base member with the curvature detection function <NUM> to be applied to a catheter, an endoscope, and so on.

In the first to third embodiments, the lumens 4a, 4b are formed in the wall <NUM>. This can minimize increase in size of the base member <NUM> due to the formation of the lumens 4a, 4b.

In the modification example, markers indicating a relative position between the first linear member <NUM> and the second linear member <NUM> are provided on the first linear member <NUM> and the second linear member <NUM>. This allows curvature of the base member <NUM> to be easily detected.

In the second embodiment, the base member with the curvature detection function <NUM> comprises the third linear member <NUM> and the fourth linear member <NUM> which extend along the longitudinal direction LD at a position apart from a position of the first linear member <NUM> and the second linear member <NUM> in the circumferential direction RD of the wall <NUM>. The third linear member <NUM> is fixed to the base member <NUM> at the first fixed position P1, and is relatively movable with respect to the base member <NUM> in the longitudinal direction LD, on the one side of the first fixed position P1 in the longitudinal direction LD. The fourth member <NUM> is fixed to the base member <NUM> at the second fixed position P2, and is relatively movable with respect to the base member <NUM> in the longitudinal direction LD, on the one side of the second fixed poison P2 in the longitudinal direction. The base member with the curvature detection function <NUM> is capable of detecting curvature of the base member <NUM> between the first fixed position P1 and the second fixed position P2 based on change in a relative position between the third linear member <NUM> and the fourth linear member <NUM>. In particular, the base member with the curvature detection function <NUM> is also capable of detecting curvature whose direction is different from that of the curvature detected based on change in a relative position between the first linear member <NUM> and the second linear member <NUM>.

Specifically, in the second embodiment, the third linear member <NUM> and the fourth linear member <NUM> are disposed in other one or more lumens 4c, 4d which are separated from the one or more lumens 4a, 4b for the first linear member <NUM> and the second linear member <NUM>. The other one or more lumens 4c, 4d are provided at a position apart from the position of the one or more lumens 4a, 4b in the circumferential direction RD of the wall <NUM>. This can reduce the risk of causing the linear members <NUM>, <NUM> and the linear members <NUM>, <NUM> to be entangled and preventing the base member with the curvature detection function <NUM> from detecting curvature in the aforementioned two directions. In addition, since the linear members <NUM>, <NUM> are disposed in the one or more lumens 4c, 4d, the risk of damaging the linear members <NUM>, <NUM>, and preventing the base member with the curvature detection function <NUM> from detecting curvature of the base member <NUM>, can be reduced.

In the modification example, markers indicating a relative position between the third linear member <NUM> and the fourth linear member <NUM> are provided on the third linear member <NUM> and the fourth linear member <NUM>. This allows curvature of the base member <NUM> to be easily detected.

In the first to third embodiments, the curvature detection system <NUM>, <NUM>, <NUM> comprises the aforementioned base member with the curvature detection function <NUM>, <NUM>, <NUM>, and the sensor <NUM> configured to detect change in a relative position between the first linear member <NUM> and the second linear member <NUM>. Such a curvature detection system <NUM> can easily detect curvature of the base member <NUM>.

In the second embodiment, the curvature detection system <NUM> comprises the aforementioned base member with the curvature detection function <NUM>, the sensor <NUM> configured to detect change in a relative position between the first linear member <NUM> and the second linear member <NUM>, and the second sensor <NUM> configured to detect change in a relative position between the third linear member <NUM> and the fourth linear member <NUM>. Such a curvature detection system <NUM> can easily detect curvature of the base member in two directions different from each other.

In the modification example, the device comprises the aforementioned base member with the curvature detection function <NUM>, <NUM>, <NUM>. Such a device can detect curvature of the base member <NUM> in a location difficult to see, which improves operability of the device.

In the aforementioned application example, the balloon catheter <NUM> comprises the balloon <NUM>, the catheter body <NUM>, and the heating member <NUM>. The catheter body <NUM> has the outer cylinder shaft <NUM> connected to the proximal end 25b of the balloon <NUM>, and the inner cylinder shaft <NUM> extending into the balloon <NUM> to be connected to the distal end 25a of the balloon <NUM>. The inner cylinder shaft <NUM> extends inside the outer cylinder shaft <NUM>. The gap between the inner cylinder shaft <NUM> and the outer cylinder shaft <NUM> serves as the liquid delivery path LP in communication with the inside space of the balloon <NUM>. The heating member <NUM>, which is for heating a liquid in the balloon <NUM>, is disposed on the outer circumferential surface of the inner cylinder shaft <NUM> in the balloon <NUM>. The inner cylinder shaft <NUM> is the aforementioned base member with the curvature detection function <NUM>, <NUM>, <NUM>. Such a balloon catheter <NUM> makes it possible to detect curvature of the inner cylinder shaft <NUM> disposed in a human body, which improves operability of the balloon catheter <NUM>.

Claim 1:
A curvature detection system (<NUM>) comprising:
a base member (<NUM>) having a longitudinal direction;
a first linear member (<NUM>) extending in the longitudinal direction; and
a second linear member (<NUM>) extending in the longitudinal direction;
wherein:
the first linear member is fixed to the base member at a first fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on one side of the first fixed position in the longitudinal direction;
the second linear member is fixed to the base member at a second fixed position different from the first fixed position, and is relatively movable with respect to the base member in the longitudinal direction, on the one side of the second fixed position in the longitudinal direction; characterized in that
the curvature detection system is capable of detecting curvature of the base member between the first fixed position and the second fixed position based on change in a relative position between the first linear member and the second linear member.