CATHETER, BALLONEXPANSIONSVERFAHREN, BALLONKOMPRESSIONSVERFAHREN

Abstract

Catheters, comprehensive: a shaft (2) that is to be inserted into a body; a balloon (3) which is attached to the shaft (2) at a distal end and is expandable by a fluid supplied from one side of a proximal end of the shaft (2); a securing element that is wrapped around the outer circumference of an intermediate section (32) between a distal end section and a proximal end section of the balloon (3) and is configured to limit the expansion of the balloon (3) at the intermediate section (32); and a cover element (5) that covers an outer circumference of the securing element, wherein an outer circumference of the locking element is not connected to an inner circumference of the cover element (5), and wherein a lubricant is arranged between the outer circumference of the locking element and the inner circumference of the cover element (5).

Description

TECHNICAL AREA

[0001] The present disclosure relates to a catheter, in particular a balloon catheter, which includes a balloon that can be expanded within a body. STATE OF THE ART

[0002] A catheter is a medical tube inserted into the body for examination or treatment. Specifically, a catheter that includes a balloon which can be expanded within the body is called a balloon catheter and is used to dilate a target portion and a constricted portion in: a tubular organ in the body, such as blood vessels, the trachea, the gastrointestinal tract, the common bile duct, and the pancreatic duct; a connecting part (entrance and exit) between these; a hole created in the body for examination or treatment (a hole, for example, punctured in the common bile duct from the stomach and the duodenal bulb); and the like.

[0003] Patent document 1 describes an elastic band section on the outer circumference of an intermediate section of the balloon to reliably widen the constricted portion. The balloon expands from shoulder sections on both sides of the band section. Consequently, the band section between the two shoulder sections forms a constricted waist section. The constricted portion, which is the target of the dilation, is supported on both sides by the expanded shoulder sections and can thus remain in a position facing the waist section. As the balloon continues to expand in this state, the constricted portion is reliably widened by the band section, which deforms elastically to accommodate the expansion.

[0004] EP 1 243 284 A1 describes a catheter with a balloon comprising a double tube consisting of an inner tube and an outer tube arranged concentrically to each other, and a balloon attached at one end to the inner tube and at the other end to the outer tube, and which also meets the following requirement (A) or (B): (A) If no air suction tube is provided between the outer tube and the inner tube, the outer diameter of the outer tube is at most 4 mm and the average bending moment of the outer tube at a distance of at most 40 cm from the tube tip at a bending angle of 45 degrees is in the range of 70 to 250 g·cm.(B) The internal diameter of a balloon expansion tube plug provided at the tip of the inner tube is within such a range that the internal diameter in height does not differ significantly from the internal diameter of a balloon expansion tube which is inserted into the inner tube and brought into contact with the balloon expansion tube plug to cause axial expansion and radial contraction of the balloon.

[0005] EP 0 425 696 A1 describes a balloon catheter in which the balloon is reinforced with composite yarns consisting of elastic and non-elastic yarns, each of which has a longer free length than the elastic yarn. The balloon exhibits high extensibility, allowing it to not only reduce its diameter during insertion into or withdrawal from a blood vessel for therapeutic purposes without wrinkling, but also to expand back to its original size and shape at any time.

[0006] DE 10 2013 219 509 A1 describes a balloon catheter with a shaft and at least one balloon arranged along the shaft, expandable by means of an expansion medium, which encloses an inner balloon space. The shaft has a first lumen, which is enclosed by an inner shaft wall and is designed and arranged to guide the expansion medium along the shaft towards a distal catheter end. A second lumen of the shaft, which is enclosed by an outer shaft wall and is designed and arranged to guide the expansion medium along the shaft towards a proximal catheter end and through the balloon, serves to expand the balloon from a contracted to an expanded state by means of the expansion medium. The first lumen is arranged within the second lumen and opens into an orifice, so that fluid can exit the first lumen and enter the second lumen.The second lumen is fluidly connected to a balloon interior via at least two openings in the shaft outer wall, a first of which is closer to a distal balloon section end than a second of which. Bibliography Patent document

[0007] Patent document 1: JP 2014-124 264 A BRIEF DESCRIPTION OF THE INVENTION Technical Problem

[0008] The balloon, no longer needed after the constricted area has been dilated, is compressed so that it can be withdrawn from the body along with a stem. During this process, the elastically deformed and stretched ligament segment is also compressed. If the ligament segment has low elasticity, it cannot be compressed sufficiently. This can lead to play between the ligament segment and the fully compressed balloon. In the worst-case scenario, the slackened ligament segment can detach from the balloon and stem and remain inside the body. If the elasticity of the ligament segment is set high to reliably prevent detachment, its elastic deformability is impaired. This makes it difficult for the ligament segment (and balloon) to perform its necessary function of dilating the constricted area.

[0009] The present disclosure was made in view of such circumstances, and one of its aims is to provide a catheter that can reliably dilate a dilation target portion. Solution to the problem

[0010] A catheter according to one aspect of the present disclosure for solving the problem described above includes: a shaft to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; a securing element wrapped around an outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon and configured to limit the expansion of the balloon at the intermediate section; and a covering element covering an outer circumference of the securing element, wherein an outer circumference of the securing element is not connected to an inner circumference of the covering element, and wherein a lubricant is arranged between the outer circumference of the securing element and the inner circumference of the covering element.

[0011] From this perspective, the balloon, which initially expands on both sides of the locking element, can reliably hold a dilation target or a constricted portion that is the dilation target in a position facing the locking element. The cover element covers the locking element, thus preventing the balloon from falling off the shaft when the balloon is compressed during catheter removal.

[0012] Another aspect of the present disclosure relates to a method for expanding a balloon.The method is a procedure for expanding a balloon in a catheter comprising a shaft to be inserted into a body, the balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft, a securing element wrapped around an outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon and configured to limit the expansion of the balloon at the intermediate section, and a covering element covering an outer circumference of the securing element, wherein the method includes reducing, when the balloon together with the securing element and the covering element is expanded by supplying a fluid into the balloon, an expansion rate of the intermediate section around which the securing element is wrapped.

[0013] Another aspect of the present disclosure relates to a catheter. The catheter includes: a shaft to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a covering element covering an outer circumference of the balloon and having a large thickness at an intermediate section between a distal end and a proximal end of the balloon compared to other sections.

[0014] Another aspect of the present disclosure relates to a catheter. The catheter includes the following: a shaft to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a visually detectable section provided in an intermediate section between a distal end and a proximal end of the balloon, and visually distinguishable from other sections of the balloon.

[0015] From this perspective, an operator of the catheter can reliably bring the intermediate section of the balloon, which is equipped with the visually detected section, close to the dilation target part while observing the visually detected section.

[0016] Another aspect of the present disclosure relates to a catheter. The catheter includes the following: a shaft to be inserted into a body and a balloon attached to the shaft at a distal end, comprising a first balloon and a second balloon which is expandable by a fluid supplied from one side of a proximal end of the shaft, the first balloon being positioned closer to an outer surface in a direction of expansion than the second balloon and being softer than the second balloon.

[0017] From this perspective, the balloon has at least a double structure in which the soft first balloon on the outside expands while adapting to the shape of the dilation target part as well as the constricted part, thereby allowing the balloon to be positioned in relation to the dilation target part and the hard second balloon on the inside can reliably expand the dilation target part.

[0018] Another aspect of the present disclosure relates to a catheter. The catheter includes the following: a shaft for insertion into a body and a balloon attached to the shaft at a distal end, which is expandable by a fluid supplied from one side of a proximal end of the shaft and includes an end-section securing structure which, after expansion, forms a constricted shape with a narrowed section in an intermediate section between a distal end and a proximal end, limiting the expansion in the distal end and the proximal end.

[0019] From this perspective, the balloon can be reliably positioned relative to the dilation target, with the constricted section forming in the intermediate segment as the balloon expands. As the dilation target expands, further widening the constricted section with fluid, the end-section stabilization structure effectively prevents excessive expansion of the distal and proximal end sections of the constricted area.

[0020] Another aspect of the present disclosure relates to a catheter. The catheter includes the following: a shaft to be inserted into a body and a balloon attached to the shaft at a distal end, which is expandable by a fluid supplied from one side of a proximal end of the shaft and includes a compression structure configured to cause an intermediate section between a distal end and a proximal end to compress before the distal and proximal end compress, at a time during compression when the fluid is discharged.

[0021] From this perspective, the balloon can be reliably compressed by the compression structure provided to the intermediate section of the balloon.

[0022] A further aspect of the present disclosure relates to a method for compressing a balloon of a catheter. The method is a procedure for compressing a balloon of a catheter, which includes a shaft to be inserted into a body and the balloon attached to the shaft at a distal end, is expandable by a fluid supplied from one side of a proximal end of the shaft, and includes a compression structure configured to cause an intermediate section between a distal end and a proximal end to compress before the distal and proximal end compress, at a point during compression when the fluid is released.The method includes increasing the compression rate of the intermediate section equipped with the compression structure when compressing the balloon by releasing the fluid from the balloon.

[0023] A further aspect of the present disclosure relates to a catheter. The catheter includes: a shaft for insertion into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a locking element wrapped around an outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon, configured to limit the expansion of the balloon at the intermediate section, and including a locking release structure that releases the locking element in at least one of a distal end section and a proximal end section of the locking element.

[0024] From this point of view, the locking element (and the balloon) can be reliably positioned with respect to the dilation target part, since the constricted section is not only formed in the balloon but also in the locking element, because the locking mechanism is relaxed in the end sections of the locking element. Advantageous effects of the invention

[0025] A dilation target can be reliably widened using a catheter and the like as described in the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 schematically illustrates an overview of EPBD with a papilla that is the dilation target. Fig. Figure 2 is a side view illustrating the external appearance of a balloon catheter according to the present embodiment. Fig. Figure 3 is a side view illustrating the external appearance of the balloon catheter according to the present embodiment. Fig. Figure 4 is a cross-sectional view of the balloon catheter according to the present embodiment. Fig. Figure 5 schematically illustrates an expanded form of a balloon and an elastic band. Fig. Figure 6 schematically illustrates a procedure for producing the balloon catheter. Fig. Figure 7 is a cross-sectional view that schematically illustrates a variety of modifications of a cover element. Fig. Figure 8 schematically illustrates a variety of examples of a cross-section along the EE line in Fig. 7. Fig. Figure 9 schematically illustrates a modification of the balloon. Fig. Figure 10 is a perspective view that schematically illustrates a modification of a shaft with which an expansion fluid can be supplied to a first balloon and a second balloon at the same time or at different times. Fig. Figure 11 is a cross-sectional view that schematically illustrates a modification of the balloon catheter. Fig. Figure 12 schematically illustrates a modification of an elastic band. DESCRIPTION OF EXECUTION FORMS

[0026] Embodiments for carrying out the present disclosure are described in detail below with reference to the drawings. In the description or the drawings, identical or equivalent components, elements, and processing operations are designated by the same reference numerals, and overlapping descriptions are omitted. The scales and shapes of the illustrated parts are specified for the sake of simplicity and to facilitate explanation and should not be interpreted as limiting unless otherwise stated. The embodiments are for illustrative purposes only and do not in any way limit the scope of protection of the present disclosure. Not all features or combinations of features described in the embodiments are essential to the present invention.

[0027] A catheter of the present disclosure can be used for the dilation of a dilation target part and a constricted part of any part in a body (e.g. tubular organ in a body such as blood vessels, trachea, gastrointestinal tract, common bile duct and pancreatic duct; a connecting part between these; a hole formed in the body for examination or treatment), but in the present embodiment a description is provided using endoscopic papillary balloon dilation (EPBD) for dilating a papilla (papilla duodeni major or duodenal papilla) which is a dilation target part.

[0028] Fig. Figure 1 schematically illustrates an overview of EPBD with a papilla 91 as the dilation target. An endoscope 10, incorporating a forceps channel 11 and a camera 12, is inserted into the duodenum 90 via the mouth. A balloon 3 is attached to a distal end (the duodenum 90 side or the internal body side) of a tubular shaft 2 of a balloon catheter 1, which is inserted into the body through the forceps channel 11. The balloon 3 can be inflated using an expansion fluid obtained by mixing contrast medium with sterile distilled water or saline as required, and supplied from the proximal end (the oral or external body side) of the shaft 2. Other types of liquid or gas, such as air, can be used as the expansion fluid if required for the purpose of the examination or treatment.

[0029] A small-diameter guidewire 6 is pre-inserted through the forceps channel 11 into a common bile duct 92 and / or a pancreatic duct 93, which is the target site of the examination or treatment, or a route leading to the target site. While the papilla 91, serving as the dilation target or opening portion, is positioned between the duodenum 90 and the common bile duct 92 and the pancreatic duct 93, the guidewire 6 has a diameter sufficiently smaller than the opening diameter of the papilla 91 and can thus pass through the papilla 91 into the common bile duct 92 or the pancreatic duct 93. In this process, an operator of the endoscope 10 and the balloon catheter 1 can safely insert the guide wire 6 into the papilla 91 while reviewing an image obtained from the camera 12, which is arranged on a side surface of the endoscope 10 to be facing the papilla 91.

[0030] A long wire lumen (hole), into which the guidewire 6 can be inserted, is formed by the interior of the tubular shaft 2 of the balloon catheter 1, i.e., from a proximal end to a distal end. When the guidewire 6 is inserted through the papilla 91 into the common bile duct 92 or the pancreatic duct 93, the distal end of the wire lumen in the shaft 2 is inserted from the proximal end, which is located on the outer side of the guidewire 6. Thus, the balloon 3 moves along the distal end of the shaft 2, guided by the guidewire 6, toward the papilla 91. In the illustrated scenario, the shaft 2 continues to advance along the guidewire 6, and the balloon 3, having reached the position of the papilla 91, is inflated by the expansion fluid. Thus, papilla 91 is enlarged from the inside.In this way, papilla 91, which is normally constricted by the sphincter of Oddi (or biliary ampullary sphincter), is dilated. Thus, a common bile duct stone formed in the common bile duct 92, for example, can be effectively removed through papilla 91.

[0031] The balloon 3, which is no longer needed after dilation of papilla 91, is compressed to the outside of the body by releasing the expansion fluid and then removed from the body along with the shaft 2 through the forceps channel 11. Once the balloon catheter 1 has been removed from the body, a medical instrument, such as another forceps or a cholangioscope, for another medical procedure, such as moving the common bile duct stone from papilla 91 into the duodenum 90 or outside the body, is inserted, if necessary, through the guidewire 6 into the dilated papilla 91.

[0032] Fig. 2 and Fig. Figure 3 shows side views illustrating the external appearance of the balloon catheter 1 according to the present embodiment. In these drawings, the balloon 3 is attached to a distal end section (left end section) of the shaft 2 of an elongated tube shape, which is inserted into the body from the right side (outer side) to the left side (inner side). Fig. Figure 2 illustrates balloon 3 in a fully compressed state. Fig. Figure 3 illustrates the balloon in a partially extended state, which is a state between the fully compressed state and a fully extended state.

[0033] A cross-section of the shaft 2 at the proximal end face, in particular a section of the shaft 2 to which the balloon 3 is not attached, is divided into two lumens, i.e. a balloon expansion lumen 21A and a wire lumen 22A, as shown in Fig. 4A can be seen, which has a cross-section along line AA in Fig. Figure 2 illustrates this. In the illustrated example, a large-diameter expansion fluid tube 21 and a small-diameter guide wire tube 22, contained on the inside of the expansion fluid tube 21, are formed as a single unit. The balloon expansion lumen 21A is a space defined by the inner circumference of the expansion fluid tube 21 and the outer circumference of the guide wire tube 22. The wire lumen 22A is a space defined by the inner circumference of the guide wire tube 22.

[0034] The balloon expansion lumen 21A communicates with a balloon expansion port 71 of a distributor 7, which is connected to the proximal end section (the right end section in Fig. 2 and Fig. 3) is provided on the outer side of the shaft 2. The expansion fluid supplied and discharged through the balloon expansion port 71 flows through the balloon expansion lumen 21A into and out of the balloon 3. Specifically, when the expansion fluid is supplied from the balloon expansion port 71, it flows through the balloon expansion lumen 21A into the balloon 3, thus expanding the balloon 3. Conversely, when the expansion fluid is discharged from the balloon expansion port 71, it flows through the balloon expansion lumen 21A out of the balloon 3, thus compressing the balloon 3.

[0035] Although not shown in detail in the figure, the expansion fluid tube 21, which forms the balloon expansion lumen 21A, has a tapered shape and a small-diameter opening end that is inserted into an interior space 21B of the balloon 3. The expansion fluid flows through this opening end between the expansion fluid tube 21 (balloon expansion lumen 21A) and the interior space 21B of the balloon 3. The interior space 21B of the balloon 3 is defined as a space by the inner circumference of the balloon 3 and the outer circumference of the guide wire tube 22. Fig. 4B, Fig. 4C and Fig. 4D illustrates the cross-sections along lines BB, CC and DD in Fig. 2 or Fig. 3 illustrate.

[0036] The wire lumen 22A communicates with a guide wire connection 72 of the distributor 7, which is connected to the proximal end section of the shaft 2 (the right end section in Fig. 2 and Fig. 3) is provided on the side of the outer body. The guide wire tube 22, which forms the wire lumen 22A, is passed through the interior 21B of the balloon 3 to the distal end (left end in Fig. 2 and Fig. 3) formed, unlike the expansion fluid tube 21, which terminates within the interior 21B of the balloon 3. As described above, the long wire lumen 22A, into which the guidewire 6 can be inserted, is formed by the interior of the tubular shaft 2 of the balloon catheter 1, i.e., from the guidewire connection 72 in the proximal end section to an opening end 221 in the distal end section. As described above with reference to Fig. As described in Figure 1, in a state where the guide wire 6 is inserted through the papilla 91 into the common bile duct 92 or the pancreatic duct 93, the opening end 221 of the guide wire tube 22, which is the distal end section of the wire lumen within the wire lumen 22A, is inserted from the proximal end section located on the outer side of the guide wire 6. Thus, the balloon 3 moves along the distal end section of the shaft 2, guided by the guide wire 6, towards the papilla 91.

[0037] A configuration of the balloon catheter 1 at the distal end, where the balloon 3 is positioned, is described in more detail. As in Fig. 4B and Fig. As illustrated in Figure 4C, the balloon 3, folded in its fully compressed state, is attached to the outer circumference of the guide wire tube 22, which forms the distal end section of the shaft 2. The interior space 21B between the inner circumference of the balloon 3 in its fully compressed state and the outer circumference of the guide wire tube 22 is shown in Fig. 4B and Fig. Figure 4C is an exaggerated illustration. The space is actually small enough to be negligible. Thus, the inner circumference of the balloon 3 in its fully compressed state and the outer circumference of the guide wire tube 22 are in almost complete contact with each other, with virtually no gap between them.

[0038] As in Fig. As illustrated in Figure 3, the balloon 3 includes three sections that differ in their expanded shape or mode of expansion: a tapered section 31 of the distal end, an intermediate section 32, and a tapered section 33 of the proximal end, in that order from the distal end toward the proximal end. The tapered section 31 of the distal end is designed to have a tapered shape, with the maximum expansion diameter increasing toward the intermediate section 32 from a distal end section 311 of the balloon 3, the diameter of which is substantially equal to that of the outer circumference of the guidewire tube 22.The tapered section 33 of the proximal end side is designed to have a tapered shape, with the maximum expansion diameter increasing towards the intermediate section 32 from a proximal end section 331 of the balloon 3, the diameter of which is essentially equal to that of the outer circumference of the guide wire tube 22 (whereby the shaft 2 further encloses the expansion fluid tube 21 with a small diameter).

[0039] In the illustrated example, the length of the tapered section 31 of the distal end and the length of the tapered section 33 of the proximal end are essentially the same, but may differ substantially in a direction connecting the distal end (opening end 221) and the proximal end (guide wire connection 72) of the shaft 2 (hereinafter referred to as an axial direction, a longitudinal direction, or a left and a right direction, and a dimension in such a direction is referred to as the length).An expansion diameter of the tapered section 31 of the distal end and an expansion diameter of the tapered section 33 of the proximal end at the points equidistant from the distal end section 311 and the proximal end section 331, respectively, are essentially the same in the illustrated example, but may differ substantially in any direction orthogonal to the axial direction (hereinafter referred to as a radial direction, an expansion direction or an orthogonal direction, and a dimension in such a direction is referred to as the expansion diameter).In the illustrated example, where the maximum expansion diameter of a proximal end section 312 of the tapered section 31 of the distal end and the maximum expansion diameter of a distal end section 332 of the tapered section 33 of the proximal end are essentially the same, the intermediate section 32, which couples these sections in the axial direction, serves as a straight tube section with an essentially uniform maximum expansion diameter.

[0040] As in Fig. 3 and Fig. As illustrated in Figure 4B, an annular elastic band 4, serving as a securing element, is wrapped around at least a portion of the outer circumference of the intermediate section 32 to limit the expansion of the balloon 3 within the intermediate section 32. In the illustrated example, a band-shaped elastic band 4 of uniform width or length in the axial direction is wrapped around the outer circumference of a central section 322 of the intermediate section 32. The elastic band 4 does not limit the expansion of a straight tubular section 321 of the distal end, which is closer to the distal end than the central section 322 within the intermediate section 32. Thus, the straight tubular section 321 of the distal end can expand easily to exhibit a substantially uniform maximum expansion diameter.Similarly, the elastic band 4 does not limit the elongation of a straight tube section 323 of the proximal end face that is closer to the proximal end face than the middle section 322 in the intermediate section 32. Thus, the straight tube section 323 of the proximal end face can easily expand to exhibit a substantially uniform maximum expansion diameter. On the other hand, the elastic band 4 limits the expansion of the central section 322 of the intermediate section 32. Thus, in a case where the pressure of the expansion fluid in the balloon 3 (interior 21B) is less than a predetermined value (for example, less than 2 atm), the expansion diameter of the central section 322 is essentially (for example, at least 20%) smaller than the expansion diameter of the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end, which is easily expandable.

[0041] In the following description, the initial diameter of the inner circumference of the elastic band 4 before the introduction of the expansion fluid is also referred to as a secured diameter. Before the expansion fluid is introduced, the outer circumference of the central section 322 of the balloon 3, in its fully compressed state, is in contact with the inner circumference of the elastic band 4, and thus the initial diameter of the balloon 3 (central section 322) is also referred to below as the secured diameter. When the expansion fluid is introduced into the balloon 3 (interior 21B), the elastic band 4 begins to deform elastically, expanding from the secured diameter or the initial diameter.As long as the pressure of the expansion fluid is lower than the predetermined value in at least one area, the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end nevertheless expand at a higher rate on both sides. Thus, the balloon 3 expands in a dumbbell shape with the central section 322, with the elastic band 4 being provided in a constricted position relative to the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end. The expansion diameter varies between positions of the elastic band 4 in the longitudinal direction. In particular, the expansion diameter in both end sections, which expand along with the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end, which expand slightly, is larger than that in the central section.

[0042] The elastic band 4 formed by any elastomeric material, such as rubber, is elastically deformed in response to the expansion of the balloon 3 when the expansion fluid is introduced into the balloon 3 (interior 21B) to expand to have a larger diameter than the secured diameter. Fig. 3 and Fig. Figure 5A illustrates a state immediately after the elastic band 4 has begun to deform elastically, with the expansion fluid being introduced into the balloon 3. In this state, the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end, whose extension is not limited by the elastic band 4, extend largely beyond the elastic band 4. On the other hand, the diameter of the middle section 322, whose extension is limited by the elastic band 4, is restricted to an extended diameter D1, which is slightly larger than a secured diameter Dmin of the elastic band 4 (the inner diameter of the elastic band 4). Fig. 2) In this state, the pressure P1 of the expansion fluid in balloon 3 (interior 21B) is lower than the predetermined value described above. Thus, the expanded diameter D1 is at least 20% (D1 < 0.8 × Dmax) smaller than the maximum expansion diameter Dmax of the straight tube section 321 at the distal end and the straight tube section 323 at the proximal end.

[0043] As an example of dimensions, the maximum expansion diameter Dmax is from 7 mm to 9 mm (preferably about 8 mm), and the secured diameter Dmin is from 1.5 mm to 2.5 mm (preferably about 2 mm). The diameter of the folded balloon 3 in its fully compressed state is Fig. The diameter of 2 is from 1.5 mm to 2.5 mm (preferably about 1.8 mm). The diameter of the shaft 2, which is closer to the proximal end than the balloon 3, is from 1.5 mm to 3 mm (preferably from 2 mm to 2.5 mm).

[0044] As in Fig. 3 and Fig. As illustrated in Figure 5A, the expansion of the balloon 3 leads to the formation of a narrowed section with a small diameter (D1) in the middle section 322 between the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end, which extend beyond the elastic band 4. When the balloon 3 expands as shown in Figure 5A, the balloon 3 forms a narrowed section with a small diameter (D1) in the middle section 322 between the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end, extending beyond the elastic band 4. Fig. 3 and Fig. 5A illustrates a state in which the central segment 322 is located near papilla 91 ( Fig. 1) The papilla 91, which is the dilation target, is supported on both sides by the straight tubular section 321 of the distal end and the straight tubular section 323 of the proximal end, which extend beyond the elastic band 4, and can remain in a position facing the constricted section (middle section 322). The constricted section can effectively support the papilla 91 on both sides when the pressure of the expansion fluid is between 0.5 atm and 1.5 atm (preferably about 1.0 atm).

[0045] When the pressure of the expansion fluid in balloon 3 (interior 21B) is increased to a predetermined value P2, the elastic band 4 stretches as shown in Fig. 5B expands to an expansion diameter D2. Furthermore, the distal end of the straight tube section 321 and the proximal end of the straight tube section 323 expand to the maximum expansion diameter Dmax. This expansion diameter D2 of the middle section 322 is 20% (D2 = 0.8 × Dmax) smaller than the maximum expansion diameter Dmax of the straight tube section 321 at the distal end and the straight tube section 323 at the proximal end. The maximum expansion diameter Dmax increases slightly according to the pressure of the expansion fluid due to the elasticity of the balloon 3 itself; however, such an increase is practically negligible. If the pressure of the expansion fluid differs from that in the Fig. The state illustrated in 5B is further increased (for example, from 4 atm to 5 atm), as shown in Fig. As illustrated in Figure 5C, the middle section 322 (elastic band 4) can be stretched to the maximum expansion diameter Dmax of the balloon 3 (intermediate section 32), which is equal to that of the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end. At least one difference between the expansion diameter of the elastic band 4 or the middle section 322 and the expansion diameter (maximum expansion diameter) Dmax of the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end will be less than 20%.

[0046] In this state, the intermediate section 32, including the central section 322 around which the elastic band 4 is wound, is in a straight tubular shape, stretched to the maximum expansion diameter Dmax, which is essentially uniform. With the elastic band 4 (central section 322) thus deforming elastically to stretch beyond the secured diameter Dmin in response to the expansion of the balloon 3, the papilla 91 is reliably dilated. If the papilla 91 can be sufficiently dilated, with the elastic band 4 stretching to any diameter D2 larger than the secured diameter Dmin and smaller than the maximum expansion diameter Dmax, as illustrated in 5B, the Fig. The illustrated state in Figure 5B is the final extended state of balloon 3, and thus the elastic band 4 may not be extended to the maximum expansion diameter Dmax, as shown in Figure 5B. Fig. Figure 5C illustrates this. The pressure of the expansion fluid in balloon 3 (interior 21B), which reaches the final expanded state, is defined as a recommended expansion pressure and is, for example, from 3 atm to 5 atm (preferably about 4 atm).

[0047] To reliably position the balloon 3 relative to the papilla 91, as described above, a contrast agent mixed into the expansion fluid supplied to the balloon 3 and two contrast markers 222 and 223, positioned at locations corresponding to the two end sections (312 and 332) of the intermediate section 32 of the balloon 3 on the outer circumference of the guidewire tube 22, are used. Using a contrast image acquired during the EPBD procedure by means of X-rays or the like, the position of the balloon 3 relative to the papilla 91 and the expansion state of the balloon 3 can be verified in real time.

[0048] To effectively hold the papilla 91 of normal size in the position facing the constricted section during such an EPBD, the width or length in the axial direction of the elastic band 4, which forms the constricted section, is preferably adjusted from 1 mm to 10 mm. To reduce the risk of the balloon 3, which is inserted through the papilla 91 into the common bile duct 92, compressing the pancreatic duct 93 and causing inflammation, the length of the balloon 3 is preferably set as short as possible. It is known that the balloon 3 must be long to prevent the expanded balloon 3 from slipping out of the papilla 91. However, with the balloon catheter 1 of the present embodiment, the constricted section formed by the elastic band 4 can reliably hold the papilla 91, and thus the balloon 3 can be of a short length.In particular, the length of the intermediate section 32 (straight tube section), which is the effective length of the balloon 3, can be adjusted from 10 mm to 40 mm. The length of the intermediate section 32 of the balloon 3 is preferably two to eight times longer than the length of the elastic band 4. For example, if the length of the elastic band 4 is 5 mm, the length of the intermediate section 32 of the balloon 3 is preferably from 10 mm (× 2) to 40 mm (× 8).

[0049] In the preceding description, the elastic band 4, which is a single elastic element with an annular and band-like shape surrounding at least a portion (central section 322) of the outer circumference of the intermediate section 32, is described as an example of the locking element. However, the locking element is not limited to this. For example, the locking element could be a plurality of elastic rings wrapped around at least a portion of the outer circumference of the intermediate section 32, or it could be a helical spring made of a nickel-titanium alloy (NiTi) or the like, wound spirally around at least a portion of the outer circumference of the intermediate section 32.These elastic elements can be any element that exerts a significant elastic force in a compression direction when expansion occurs due to the pressure of the expansion fluid, and do not necessarily have to return completely to their original state (secured diameter or initial diameter) after the expansion fluid is released. Thus, the elastic element may remain somewhat deformed (i.e., plastic deformation) after the expansion fluid is released. The securing element can be an element that exhibits no or limited elasticity. For example, a plastic element made of metal or the like, which can be expanded beyond the secured diameter by plastic deformation due to the expanding balloon 3, but cannot be compressed after expansion, can be used as the securing element.Furthermore, a rigid element that is practically non-deformable, maintains the secured diameter as long as the pressure of the expansion fluid in the balloon 3 is lower than a predetermined value, and breaks as soon as the pressure of the expansion fluid in the balloon 3 reaches or exceeds the predetermined value, can be used as the securing element.

[0050] The locking element, which is the elastic element or the element with plasticity, can break if the pressure of the expansion fluid in the balloon 3 increases to a predetermined diameter after the elastic or plastic deformation of the locking element (for example, the diameter D2 in Fig. 5B). Therefore, if the locking element is removed in this way, the central section 322 automatically expands to the maximum expansion diameter Dmax, as shown in Fig. Figure 5C illustrates this (where the elastic band 4 is broken). As a result, the intermediate section 32 as a whole expands to the substantially uniform maximum expansion diameter Dmax to assume a straight tubular shape. A cover element 5, described below, covers the retaining element, including the element with plasticity after plastic deformation or the rigid element that has broken, from the outer circumference, thereby preventing the retaining element from falling off the balloon 3 and the shaft 2. Since the retaining element is thus prevented from falling off inside the body, it can also be formed using a material not generally used for medical purposes.The securing element (the elastic band 4 or the like) can be formed using a material that does not transmit X-rays in order to have a contrast function similar to that of the contrast markers 222 and 223 provided on the outer circumference of the guide wire tube 22.

[0051] The securing element remaining in the cover element 5 can also function as an alignment marker (visually detected section) visible via the camera 12 of the endoscope 10. Such a visually detected section is provided in the intermediate section 32 (specifically the middle section 322) of the balloon 3 and has a feature that is visually distinguishable from other sections of the balloon 3 (for example, the straight tube section 321 of the distal end, the straight tube section 323 of the proximal end, the tapered section 31 of the distal end, and the tapered section 33 of the proximal end). For example, the elastic band 4 (secure element), which is the visually detected section, has a color and / or pattern that differs from those of the other sections of the balloon 3. For example, the balloon 3 is typically colorless or white and has no pattern.Thus, the elastic band 4 is provided with an achromatic color other than white (gray or black) or any chromatic color and / or is marked with any pattern to serve as the visually recognized section, distinguishable from the balloon 3. The balloon catheter 1 operator can safely and reliably operate the balloon catheter 1 while visually checking the elastic band 4, which serves as the visually recognized section distinguishable from the balloon 3 and the target site, such as papilla 91.

[0052] The visually detected section is not limited to the elastic band 4, which is the securing element, and can be formed in the balloon 3 and / or the cover element 5. If the visually detected section is formed as part of the balloon 3, the intermediate section 32 (in particular the central section 322) in which the visually detected section is to be formed can be provided with a color and / or pattern that differs from those in the other sections. In particular, a section of the balloon 3 that is to be the visually detected section can have a material or property that differs from those in other sections in order to exhibit a difference in color, pattern, or the like, in order to be visually distinguishable from the other sections.If the visually detectable section is formed in the cover element 5, a position corresponding to the intermediate section 32 (in particular the central section 322) of the balloon 3, where the visually detectable section is to be formed, may be provided with a color and / or pattern that differs from those in the other sections. The visually detectable section may be applied to the balloon catheter 1 without the elastic band 4 and / or the cover element 5. In this case, the visually detectable section is preferably formed in the balloon 3 as described above, but an annular guide band (which does not serve as a securing element) may be wrapped around the outermost circumference of the intermediate section 32 (in particular the central section 322) of the balloon 3 in addition to or instead of the elastic band 4.

[0053] The cover element 5 covers the outer circumference of the elastic band 4, as shown in Fig. Figure 4B illustrates this and covers the outer circumference of balloon 3, as shown in Fig. 4C and Fig. 4D illustration. The radial thickness of the cover element 5 (unextended) is, for example, approximately 50 µm, and the radial thickness of the elastic band 4 (unextended) is, for example, approximately 100 µm. The cover element 5 is a tube with an elongated tubular shape, formed using any elastic material such as polyurethane. Fig. 3 is the distal end section of the cover element 5 (not illustrated) fixed by a short fastening tube 51 made of thermoplastic elastomer or the like in a state where the outer circumference of the guide wire tube 22, extending from the distal end section 311 of the balloon 3 to the distal end face, is covered. The proximal end section of the cover element 5 is fixed by a short fastening tube 52 made of thermoplastic elastomer or the like in a state where the outer circumference of the shaft 2, extending from the proximal end section 331 of the balloon 3 to the proximal end face, is covered. The fastening tube 51 has a smaller diameter than the fastening tube 52 due to a diameter difference, with the guide wire tube 22 having a small diameter at the distal end face and the shaft 2 having a large diameter at the proximal end face.

[0054] As described above, both end sections of the cover element 5, which are longer than the elastic band 4 and the balloon 3, are attached to the outer circumference of the shaft 2 (including the guide wire tube 22) to sections that are closer to the distal and proximal ends than the elastic band 4. The cover element 5 may be shorter than the balloon 3 and have both end sections fixed to the outer circumference of the balloon 3 to sections that are closer to the distal and proximal ends than the elastic band 4. For example, both end sections of the cover element 5 may be fixed to the outer circumference of the tapered section 31 of the distal end and the tapered section 33 of the proximal end, or to the outer circumference of the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end.In some cases, an electrode for medical procedure, measurement, or the like, or a distal end chip (an element in which the opening end 221 is formed), which forms the distal end section of the balloon catheter 1 or the shaft 2, may be provided closer to the distal end face than the balloon 3 in the balloon catheter 1. The cover element 5 may be fixed to the outer circumference of (a part of) such an electrode or distal end chip.

[0055] With these configurations, the cover element 5 covers the outer circumference of the balloon 3 that is not wrapped by the elastic band 4, as well as the outer circumference of the elastic band 4 itself, thus preventing the elastic band 4 and other securing elements from falling off the balloon 3. Furthermore, in the illustrated example, the cover element 5 also covers the outer circumference of the shaft 2 (including the guide wire tube 22) to which the cover 3 is not attached, as well as the outer circumference of the elastic band 4 and the balloon 3. Therefore, not only are the elastic band 4 and other securing elements prevented from falling off the balloon 3 and the shaft 2, but the balloon 3 can also be effectively compressed by the elasticity of the cover element 5 when the balloon catheter 1 is removed.

[0056] As described above, the cover element 5 has both end sections fixed to the outer circumference of the shaft 2 and / or the balloon 3 at both ends, but has no other sections fixed to the outer circumference of the balloon 3 and / or the elastic band 4 besides the two end sections. Thus, as in Fig. Figure 4B illustrates that the elastic band 4, which is covered from the outside by the cover element 5, is not connected to the inner circumference of the cover element 5. Similarly, the elastic band 4 is not connected to the outer circumference of the balloon 3 (central section 322) on the inside. Nevertheless, due to the elasticity of the cover element 5, the elastic band 4 is pressed against the balloon 3 from the outside to remain in a predetermined position (central section 322) and is thus prevented from falling off the balloon 3. In patent document 1, a band section is welded to a balloon, but in the present embodiment, the elastic band 4 does not need to be connected to the balloon 3 (and the cover element 5). Thus, the balloon catheter 1 can be manufactured economically.Furthermore, if the band section is welded to the balloon as in patent document 1, the desired expansion of the balloon and the band section could be inhibited at the welded section. In the present embodiment, the elastic band 4 and the balloon 3 are not welded or connected, so that their desired expansion can be achieved without inhibiting the expansion of the other.

[0057] The cover element 5 with elasticity, in the state in Fig. 2, in which the balloon 3 is not expanded, pushes the balloon 3 and / or the elastic band 4 from the outside to maintain the fully compressed state of the balloon 3. When the expansion fluid is supplied to the balloon 3 (interior 21B), the balloon 3 and / or the elastic band 4 expand, and thus the cover element 5 deforms elastically to expand. The initial diameter or cover diameter (the inner diameter of the cover element 5 at a position where the elastic band 4 is not provided, as in Fig. (4C illustrated), when the elastic deformation of the cover element 5 begins, is smaller than the secured diameter Dmin of the in Fig. 4B illustrated elastic bands 4.

[0058] To achieve the extended shape of the balloon 3 and the elastic band 4, as shown in Fig. As illustrated in Figure 5, to achieve this, the elastic modulus of balloon 3 is set to be higher than that of elastic band 4, and the elastic modulus of elastic band 4 is set to be higher than that of cover element 5. Since the elastic modulus (also known as Young's modulus) indicates how low the deformability is, balloon 3 is less likely to deform than elastic band 4, and elastic band 4 is less likely to deform than cover element 5. In other words, cover element 5, elastic band 4, and balloon 3 are, in that order, in terms of deformability. If balloon 3 and / or elastic band 4 deform on the inside, the cover element 5, with the highest deformability, expands to essentially follow its expansion completely.

[0059] When the expansion fluid enters balloon 3 (interior 21B) in a fully compressed state Fig. When 2 is supplied, the balloon 3 begins to expand from its folded state, and the elastic band 4, which is wrapped around and covers the central section 322 of the balloon 3 and the cover element 5, also expands. Fig. Figure 5A illustrates a state in which the pressure of the expansion fluid in the balloon 3 (interior 21B) has reached P1. As described above, the balloon 3 expands into a dumbbell shape, with the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end extending beyond the central section 322, and with the central section 322 being limited to the expanded diameter D1, which is at least 20% smaller than the maximum expansion diameter Dmax.

[0060] If the pressure of the expansion fluid in balloon 3 (interior 21B) changes from the state in Fig. If 5A is further increased to P2 (> P1), the elastic band 4 deforms further elastically, as in Fig. 5B illustrates this to understand the extended diameter D1 in Fig. to expand beyond 5A, and the cover element 5, which covers the elastic band 4, also expands to follow this expansion. The tapered section 31 of the distal end and the tapered section 33 of the proximal end of the balloon 3 were designed to accommodate the maximum expansion diameter at the point of Fig. 5A expanded and therefore essentially do not expand further, even if the pressure of the expansion fluid in Fig. 5B increases due to the high elasticity of balloon 3. Furthermore, the distal end of the straight tube section 321 and the proximal end of the straight tube section 323 expand to the maximum expansion diameter Dmax. When the pressure of the expansion fluid in balloon 3 (interior 21B) increases from the state in Fig. If 5B is further increased to P3 (> P2), the elastic band 4 expands to the maximum expansion diameter Dmax, as shown in Fig. 5C illustrates this, and the elastic band 4, which covers the cover element 5, also expands. Even if the pressure of the expansion fluid in balloon 3 (interior 21B) continues to rise from the pressure shown in Fig. As the temperature rises in the illustrated state of 5C, the balloon 3 does not expand further due to its high elasticity.

[0061] When the pressure of the expansion fluid in the balloon 3 (interior 21B) is reduced and / or the expansion fluid is discharged from the balloon expansion port 71 to remove the balloon catheter 1, the balloon 3 is effectively compressed due to the elasticity of the elastic band 4 and / or the cover element 5 and can thus be brought into a state close to the fully compressed state. Fig. 2 before expansion. In this case, the elastic band 4 acts as a compression structure, causing the intermediate section 32 (specifically the middle section 322) of the balloon 3 to compress before the distal end section (including the straight tube section 321 of the distal end) and the proximal end section (including the straight tube section 323 of the proximal end) compress at the time of compression when the expansion fluid is released from the balloon 3. In other words, the elastic band 4, acting as a compression structure, causes the intermediate section 32 of the balloon 3, which is equipped with the compression structure, to compress at a higher rate than the distal and proximal end sections. The elasticity of the elastic band 4, which is stretched to the maximum expansion diameter Dmax, as shown in Fig. 5C illustrates that the original elasticity (for example, at the point of Fig. 5A) will be reduced. With the remaining elasticity at the point of Fig. 5C nevertheless causes the elastic band 4 to compress the intermediate section 32 first at the time of compression of the balloon 3, so that the balloon 3 as a whole can be effectively compressed while successively entering the states in Fig. 5B and Fig. 5A in this order.

[0062] As described above, since the balloon 3 is effectively compressed due to the elasticity of the elastic band 4 and / or the cover element 5, it can be prevented that the balloon 3 enters the forceps channel 11 ( Fig. 1) the endoscope 10 remains stuck, and thus the balloon catheter 1 can be easily removed. Regardless of the state of expansion or compression of the balloon 3, the elastic band 4 is held in place by the elasticity of the cover element 5 while being pressed against the balloon 3 from the outside, effectively preventing the elastic band 4 or other securing elements from falling off the balloon 3.

[0063] In patent document 1, which includes the risk of the band section falling off, the elasticity of the band section must be higher than necessary to prevent falling off. In contrast, in the present embodiment, the cover element 5 provides the fall-prevention function, and thus the risk of falling off does not need to be considered when designing the elasticity, dimensions, shape, and the like of the elastic band 4. Therefore, the design can be optimized solely to achieve the desired extended shape, as shown in [reference to patent document 1]. Fig. 5 illustrates.

[0064] Fig. Figure 6 schematically illustrates a procedure for producing balloon catheter 1. Fig. 6A The balloon 3 is attached to the outer circumference at the distal end of the shaft 2. The distal end section 311 of the balloon 3 is connected to the outer circumference of the guide wire tube 22 of the shaft 2 and tightly sealed to prevent the expansion fluid from leaking out of the balloon 3 (interior 21B). The proximal end section 331 of the balloon 3 is connected to the expansion fluid tube 21 and the guide wire tube 22 to the outer circumference of the shaft 2, as shown in Fig. 4A, and is sealed in such a way that the expansion fluid of the balloon 3 (interior 21B) does not leak out. While the guide wire tube 22 of the shaft 2 extends through the entire length of the balloon 3, the expansion fluid tube 21 terminates within the interior 21B of the balloon 3, and thus the expansion fluid can flow into and out of the interior 21B of the balloon 3 through the opening end of the expansion fluid tube 21. The balloon 3, with its two end sections 311 and 331 connected to the outer circumference of the shaft 2 as described above, is wound around the outer circumference of the shaft 2 to be folded into a shape consisting of a plurality of (for example, three) wings.

[0065] In Fig. 6B, the elastic band 4 is attached to the central section 322 of the folded balloon 3. For example, the distal end of the guide wire tube 22 is inserted into the elastic band 4, and the elastic band 4 slides to the central section 322 of the balloon 3. During this process, the elastic band 4 does not need to be connected to the outer circumference of the balloon 3 (central section 322). A lubricant such as silicon oil or silicon powder may be added or applied between the outer circumference of the balloon 3 and the inner circumference of the elastic band 4 for easier assembly or the like. Fig. 6C, the cover element 5, which has an elongated tubular shape, is attached to cover the folded balloon 3 and the elastic band 4. It has distal and proximal end sections that are fixed by the fastening tube 51 and the fastening tube 52. In this process, the cover element 5 does not need to be connected to any part of the balloon 3 other than the distal end section 311 and the proximal end section 331, and to the outer circumference of the elastic band 4. A lubricant such as silicon oil or silicon powder is added or applied between the outer circumference of the elastic band 4 and the inner circumference of the cover element 5 for easier assembly or the like.

[0066] The elastic band 4 and the cover element 5, both of which exhibit elasticity, are separate elements in the Fig. The embodiment illustrated in Figure 4B is provided, but they can be formed in one piece from the same elastic material. With such an elastic element, the function of the elastic band 4 is achieved, wherein the thickness at the position corresponding to the central section 322 of the balloon 3 is greater than that in other sections.

[0067] Fig. Figure 7 is a cross-sectional view schematically illustrating a variety of modifications of the cover element 5. These cover elements 5 are a coating material 53 that covers at least a portion of the boundary between the elastic band 4 (locking element) and the outer circumference of the balloon 3. Any suitable material can be used as the coating material 53. For example, the coating material 53 is formed by any elastic material such as polyurethane, as in the embodiment described above. The coating material, in a fluid or liquid form, is applied to a desired section of the outer circumference of the elastic band 4 and the balloon 3 and then dried. As a result, a coating layer (coating material 53), serving as the illustrated cover element 5, is formed axially over both the elastic band 4 and the balloon 3.Alternatively, the balloon 3, to which the elastic band 4 is attached, can be immersed (placed) into the coating material in a fluid or liquid form and then dried to form the coating layer (coating material 53) as the covering element 5.

[0068] The coating material 53 covers at least one of: at least a part of the boundary between the balloon 3 and the distal end of the elastic band 4 (left end in Fig. 7) and at least part of the boundary between balloon 3 and the proximal end (right end in Fig. 7) of the elastic band 4. In particular, the coating material 53 can be designed to cover the boundary between the balloon 3 and the distal end and the proximal end of the elastic band 4, as shown in Fig. Figure 7A illustrates that the design can be configured to cover only the boundary between the balloon 3 and the distal end of the elastic band 4, as shown in Fig. Figure 7B illustrates, or can be designed to cover only the boundary between the balloon 3 and the proximal end of the elastic band 4, as shown in Fig. Figure 7C illustrates this. In each case, the elastic band 4 and the balloon 3 are attached via the coating material 53, thus effectively preventing the elastic band 4 from being displaced from the predetermined position (central section 322) of the balloon 3. To reliably provide this displacement prevention function, the coating material 53 preferably covers half the length of the elastic band 4 in the axial direction (left and right directions in the Fig. 7), as in Fig. 7A to Fig. 7C illustrates.

[0069] Fig. Figure 8 schematically illustrates a variety of examples of a cross-section along the EE line in Fig. 7. The figure illustrates only the balloon 3, the elastic band 4, and the coating material 53 (covering element 5); other configurations within the balloon 3 and the like are omitted. As in Fig. As illustrated in Figure 8A, the coating material 53 can cover the entire outer circumference of the elastic band 4 and / or the balloon 3. As shown in Fig. As illustrated in Figure 8B, the coating material 53 can only cover part of the outer circumference of the elastic band 4 and / or the balloon 3. In the example of Fig. 8B The coating material 53 covers half (upper half) of the outer circumference of the elastic band 4 and / or the balloon 3, and the remaining half (lower half) is not coated with the coating material 53 and is therefore exposed. It should be noted that the length of the coating material 53 in the circumferential direction that covers the outer circumference of the elastic band 4 and / or the balloon 3 is not half the circumference as shown in Figure 8B. Fig. 8B is limited and can be larger than half the circumference or smaller than half the circumference.

[0070] As in Fig. As illustrated in Figure 8B, the coating material 53, which does not cover the entire outer circumference of the elastic band 4 and / or the balloon 3, has the advantage that the expansion of the balloon 3 and the elastic band 4 is less likely to be inhibited by the coating material 53. The coating material 53, which covers only part of the outer circumference of the balloon 3 and the elastic band 4, can separate, tear, or break when the balloon 3 and the elastic band 4 expand from the inside, but this facilitates (does not prevent) the expansion of the balloon 3 and the elastic band 4. The coating material 53, which intentionally loses its function when the balloon 3 and the elastic band 4 expand, is specialized in the function of preventing the displacement of the balloon 3, which is folded in its fully compressed state, and the elastic band 4 before expansion. As in Fig. As illustrated in Figure 8C, with a variety of coating materials 53 provided at a variety of different positions in the circumferential direction of the elastic band 4 and / or the balloon 3 while separated from each other, the coating material 53 may more easily lose its function when the balloon 3 and the elastic band 4 expand.

[0071] Fig. Figure 9 schematically illustrates a modification of the balloon 3. In this figure, only the shaft 2, the balloon 3, and the attachment tube 51, which is practically the distal end of the balloon 3, are shown; other configurations inside and outside the balloon 3 are omitted. The balloon 3 according to the present modification is attached to the distal end of the shaft 2 (left side in Figure 9). Fig. 9) attaches and encloses a first balloon 3A and a second balloon 3B, which are connected by a proximal end (right side in Fig. 9) the expansion fluid supplied to shaft 2 can be expanded. The first balloon 3A is positioned closer to the outside in the expansion direction than the second balloon 3B, and the second balloon 3B is positioned closer to the inside in the expansion direction than the first balloon 3A. Thus, balloon 3 has a double structure, achieved with the first balloon 3A on the outside and the second balloon 3B on the inside.

[0072] As in Fig. As illustrated in Figure 9A, the first balloon 3A on the outside expands before the second balloon 3B on the inside does. Specifically, the first balloon 3A is formed by a material that is softer than the second balloon 3B. Thus, even if the expansion fluid is supplied to the first balloon 3A and the second balloon 3B from the balloon expansion lumen 21A essentially simultaneously, the first balloon 3A expands before the second balloon 3B does. For example, the soft first balloon 3A on the outside is formed by urethane or the like, and the hard second balloon 3B on the inside is formed by nylon or the like. The first balloon 3A may have a smaller thickness than the second balloon 3B to be softer.The expression "the first balloon 3A is softer than the second balloon 3B" means that the first balloon 3A expands by a greater amount than the second balloon 3B and / or that the expansion start time of the first balloon 3A is earlier than that of the second balloon 3B, provided that the pressure of the expansion fluid supplied to the balloons is equal. The stiffness of the first balloon 3A and the second balloon 3B may be irrelevant, and the first balloon 3A may expand before the second balloon 3B by supplying the expansion fluid first to the first balloon 3A from the first balloon expansion lumen and then to the second balloon 3B from the second balloon expansion lumen.

[0073] Fig. Figure 10 is a perspective view schematically illustrating a modification of a shaft 2 by which an expansion fluid can be supplied to the first balloon 3A and the second balloon 3B at the same or different times. In this figure, configurations (including balloon 3) other than the shaft 2 are omitted. The shaft 2 encloses the expansion fluid tube 21 and the guide wire tube 22, as described above with reference to Fig. 4 and the like are described. Nevertheless, shaft 2 differs from that described in Fig. Figure 4 illustrated that the expansion fluid tube 21 is divided into a first expansion fluid tube 211 and a second expansion fluid tube 212. The in Fig. 4 and the like illustrated balloon expansion lumen 21A is divided into a first balloon expansion lumen 211A, which is formed in the first expansion fluid tube 211, and a second balloon expansion lumen 212A, which is formed in the second expansion fluid tube 212.

[0074] The opening end of the distal end of the first expansion fluid tube 211, which forms the first balloon expansion lumen 211A, is inserted into an interior 211B of the first balloon 3A ( Fig. 9) introduced. The interior space 211B of the first balloon 3A is a space defined by an inner circumferential surface and the outer circumferential surface of the first balloon 3A on the outside and of the second balloon 3B on the inside of the balloon 3 with the double structure. The opening end of the distal end face of the second expansion fluid tube 212, which forms the second balloon expansion lumen 212A, is inserted into an interior space 212B of the second balloon 3B ( Fig. 9) introduced. The interior 212B of the second balloon 3B is a space defined by the inner circumferential surface of the second balloon 3B. Conversely, the opening end of the first expansion fluid tube 211 can be inserted into the interior 212B of the second balloon 3B on the inside, and the opening end of the second expansion fluid tube 212 can be inserted into the interior 211B of the first balloon 3A on the outside.

[0075] In shaft 2 of the in Fig. In the illustrated example 10, the opening end of the first expansion fluid tube 211 and the opening end of the second expansion fluid tube 212 are located at different positions in the axial direction. Specifically, the opening end of the first expansion fluid tube 211 is positioned axially to the balloon 3 on the proximal end (for example, at the position of the tapered section 33 of the proximal end). The opening end of the second expansion fluid tube 212 is positioned axially to the balloon 3 on the distal end (for example, at the position of the tapered section 31 of the distal end). The distal end of the guide wire tube 22, which is illustrated as being located in the same position as the opening end of the second expansion fluid tube 212, is also shown in the illustration. Fig. 10, is indeed positioned at the distal end (opening end 221) of the balloon catheter 1, as described above with reference to Fig. 3 and the like. The opening end of the first expansion fluid tube 211 and the opening end of the second expansion fluid tube 212 can be located in the same position in the axial direction.

[0076] As in Fig. As illustrated in Figure 9A, the intermediate section 32 of the first balloon 3A on the outside, which expands in front of the second balloon 3B on the inside, can narrow into a constricted shape with a narrowed section in the middle section 322 instead of the straight tube shape, as shown in Figure 9A. Fig. Figure 6A illustrates expansion. For example, the intermediate section 32 of the first balloon 3A is formed (manufactured) to have an initial shape with a constriction. Thus, the first balloon 3A naturally expands into the constricted shape when the expansion fluid is supplied from the first balloon expansion lumen 211A to the interior 211B. When the first balloon 3A expands as shown in Figure 6A, the expansion fluid is formed in the first balloon 3A. Fig. 9A illustrates a state in which the central segment 322 is located near the papilla 91 ( Fig. 1) The distal and proximal end sections of the first balloon 3A, which is the dilation target, have a larger diameter than the constricted section (midsection 322) that supports the papilla 91 from both sides. Thus, the constricted section (midsection 322) of the first balloon 3A can be reliably positioned relative to the papilla 91, which is the dilation target.

[0077] The intermediate section 32 of the first balloon 3A can expand into the straight tube shape, as shown in Fig. Figure 6A illustrates this. As described above, the first balloon 3A is formed by a material that is softer than the second balloon 3B and can therefore deform and expand to conform to the shape of the dilation target part, such as papilla 91, even as the first balloon 3A expands into the straight tubular shape. Consequently, the first balloon 3A naturally forms a constricted shape, similar to that shown in Fig. 9A, to support papilla 91 or the like from both sides. Thus, the first balloon 3A, which expands into the straight tube shape, is also positioned, while the narrowed section is naturally formed at the position of papilla 91 and the like.

[0078] In Fig. 9B, which describes a state after the one in Fig. As illustrated in Figure 9A, the first balloon 3A on the outside continues to expand through the first balloon expansion lumen 211A, and the second balloon 3B on the inside essentially begins to expand through the second balloon expansion lumen 212A. As described above, there is a difference in the start time of expansion between the first balloon 3A and the second balloon 3B because the second balloon 3B is harder than the first balloon 3A and / or because the time at which the expansion fluid begins to be supplied to the second balloon 3B is later than the time at which the expansion fluid begins to be supplied to the first balloon 3A. The intermediate section 32 of the second balloon 3B on the inside expands into the straight tube shape as shown in Figure 9A. Fig. 6A. The constricted section formed on the outside of the intermediate section 32 (central section 322) of the first balloon 3A shrinks due to the increased pressure of the expansion fluid, which is continuously supplied to the first balloon 3A, and the pressure in the expansion direction from the second balloon 3B, which expands from the inside of the first balloon 3A into the straight tube shape.

[0079] In Fig. 9C, which describes the state after the in Fig. As illustrated in Figure 9B, the expansion of the second balloon 3B essentially ends on the inside through the second balloon expansion lumen 212A. In the finally expanded state of the second balloon 3B, the intermediate section 32 of it has transformed into the straight tube shape with the maximum expansion diameter Dmax as shown in Figure 9B. Fig. 5C expanded. The intermediate section 32 of the soft first balloon 3A on the outside has followed the hard second balloon 3B to deform into the straight tubular shape, which has a diameter that is essentially equal to the maximum expansion diameter Dmax. Thus, the constricted section formed in the intermediate section 32 (central section 322) of the first balloon 3A on the outside essentially does not exist in the finally expanded state of the second balloon 3B on the inside. In this state, the dilation target part, such as the papilla 91, which is held by the constricted section (central section 322) of the soft first balloon 3A on the outside, is effectively expanded (spread) by the hard second balloon 3B on the inside.

[0080] Fig. Figure 11 is a cross-sectional view schematically illustrating a modification of the balloon catheter 1. Only the intermediate section 32 of the balloon 3 and the securing bands 41 and 42 described below are shown in the figure; other configurations are omitted. The balloon 3 according to the present modification includes a securing band 41 of the distal end and a securing band 42 of the proximal end, which serve as an end-section securing structure and an end-section limiting element, respectively. These bands restrict the expansion in the distal end (including the straight tube section 321 of the distal end) and in the proximal end (including the straight tube section 323 of the proximal end) after expansion into a constricted shape, with the constricted section in the intermediate section 32 (in particular the middle section 322) located between the distal end and the proximal end.

[0081] As in Fig. Figure 11A illustrates that the central section 322 of balloon 3 expands instead of maintaining its straight tube shape, as shown in Fig. Figure 6A illustrates the narrowed shape with the constricted section. In particular, the central section 322 of the balloon 3 is formed (manufactured) to have an initial shape with a constriction. Thus, the central section 322 of the balloon 3 naturally expands into the constricted shape when the expansion fluid is supplied from the balloon expansion lumen 21A to the interior 21B. When the balloon 3 is as shown in Figure 6A, the balloon 3 expands into the constricted shape. Fig. 11A illustrates a state in which the central segment 322 is located near the papilla 91 ( Fig. 1) The distal end section (especially the straight tube section 321 of the distal end) and the proximal end section (especially the straight tube section 323 of the proximal end) have a larger diameter than the constricted section (middle section 322) that supports the papilla 91 from both sides. Thus, the constricted section (middle section 322) of the balloon 3 can be reliably positioned with respect to the papilla 91, which is the dilation target.

[0082] The securing band 41 of the distal end, which is wrapped around the outer circumference of the straight tube section 321 of the distal end, which is closer to the distal end (left side in Fig. 11) than the narrowed middle section 322, limits the extent of the balloon 3 in the straight tube section 321 of the distal end. Similarly, the securing band 42 of the proximal end, which is wrapped around the outer circumference of the straight tube section 323 of the proximal end, which is closer to the proximal end (right side in Fig. 11) as the narrowed central section 322 is, the expansion of the balloon 3 in the straight tube section 323 of the proximal end. Even if the pressure of the expansion fluid in the balloon 3 differs from that in Fig. 11A on the in Fig. As 11B increases, the securing band 41 of the distal end in the straight tube section 321 of the distal end limits the expansion, and thus the diameter hardly decreases from that in Fig. 11A. In the straight tube section 323 of the proximal end, the securing band 42 of the proximal end limits the expansion, and thus the diameter hardly decreases from that in Fig. 11A to.

[0083] On the other hand, the central section 322, without the securing bands 41 and 42, extends from the state in Fig. 11A to the state in Fig. 11B to have the same diameter as the straight tube section 321 of the distal end and the straight tube section 323 of the proximal end. Consequently, the intermediate section 32, as in Fig. Figure 11B illustrates an essentially straight tube shape extending completely over the straight tube section 321 of the distal end, the middle section 322, and the straight tube section 323 of the proximal end. Thus, in the finally expanded state of the balloon 3, Fig. 11B is essentially not a narrowed section, which is in the central section 322 in Fig. 11A is formed. In this state, the dilation target part, such as the papilla 91, which is formed by the narrowed section in the middle section 322 in Fig. 11A is held by the central section 322 in the essentially straight tube shape in Fig. 11B effectively widened (spread).

[0084] According to the present modification, the balloon 3 can be reliably positioned with respect to the dilation target portion, with the constricted section being formed in the intermediate section 32 (middle section 322) at the time the balloon 3 expands. As the constricted section is further expanded by the expansion fluid to enlarge the dilation target portion, the securing band 41 of the distal end and the securing band 42 of the proximal end, which act as end-section securing structures, effectively prevent the distal end section (straight tube section 321 of the distal end) and the proximal end section (straight tube section 323 of the proximal end) on the distal and proximal ends of the constricted section from over-expanding.

[0085] The end-section securing structure is not limited to the securing bands 41 and 42 wrapped around the outer circumference of the straight tube sections 321 and 323, and can be formed by a distal end section (including the straight tube section 321 of the distal end side) and the proximal end section (including the straight tube section 323 of the proximal end side) that are harder than the intermediate section 32 (especially the middle section 322). Similar to the above with reference to Fig. In accordance with the meaning of the term "soft" as described in section 9, the term "hard" indicates that the extent of elongation of the distal and proximal end sections, to which the expansion fluid is supplied at the same pressure, is less than that of the intermediate section 32 (the middle section 322 being the constricted section). Thus, the "soft" constricted section (middle section 322) can easily expand when the pressure of the expansion fluid increases, as during the transition from Fig. 11A to Fig. 11B. On the other hand, the “hard” distal end section (the straight tube section 321 of the distal end) and proximal end section (the straight tube section 323 of the proximal end) hardly expand, even when the pressure of the expansion fluid increases, as during the transition from Fig. 11A to Fig. 11B. The straight tubular section 321 of the distal end and the straight tubular section 323 of the proximal end, which are “harder” than the middle section 322, can be formed by a material (for example, nylon) that is harder than the middle section 322 (for example, urethane), can be obtained with a thickness greater than that of the middle section 322, or can be obtained with a multilayer balloon with a greater number of layers than the middle section 322.

[0086] Fig. Figure 12 schematically illustrates a modification of the elastic band 4. Only the elastic band 4 is shown in the figure, and other configurations are omitted. The elastic band 4 according to the present modification is a securing element that is wrapped around the outer circumference of the intermediate section 32 (in particular, the middle section 322) between the distal end section and the proximal end section of the balloon 3 to limit the expansion of the balloon 3 in the intermediate section 32, and includes a securing release structure that releases the limitation in at least one of the distal end section and the proximal end section. In the Fig. The 12 illustrated example shows a securing relaxation structure 44 of the distal end and a securing relaxation structure 45 of the proximal end with an axially directed recessed and protruding shape along the circumferential direction of an annular and band-shaped band body 43 of the elastic band 4 formed both at the distal end and at the proximal end of the band body 43.

[0087] The recessed and protruding shape of the locking release structures 44 and 45 is formed by a plurality of notches in the axial direction (recesses of the recessed and protruding shape) that are formed along the circumferential direction in the distal end section and the proximal end section of the annular and band-shaped elastic band 4, illustrated in Fig.3 and the like. The notches in the axial direction, which form the locking release structures 44 and 45, can be slots or cuts in the axial direction.

[0088] With such locking release structures 44 and 45, the locking force in the end sections of the elastic band 4 is relaxed compared to the locking force in the central section (band body 43). As a result, the end sections of the elastic band 4, where the locking release structures 44 and 45 are formed, extend beyond the band body 43 in the central section. Thus, in addition to the constricted section in the balloon 3, a tiny constricted section is formed in the elastic band 4, allowing the constricted elastic band 4 (and the balloon 3) to be reliably positioned as a constricted section relative to the dilation target part. The locking release structure in the end sections of the elastic band 4 can be any structure that achieves a gradation (reduction) of the locking force relative to that in the central section.For example, the elastic band 4 is formed by an end-section band (first securing element) provided in the distal and / or proximal end section, and a middle-section band (second securing element) provided in the remaining section, which is the middle section. With the axial width and radial thickness of the end-section band being set smaller than those of the middle-section band (corresponding to the band body 43), the securing force of the end-section band can be made smaller than that of the middle-section band, thereby forming the securing release structure (end-section band) in the end section of the elastic band 4.

[0089] The present disclosure has been described above with reference to the embodiments. It is understood by those skilled in the art that the embodiments are examples, that various modifications in the combination of components and processing operations are possible, and that such modifications are also within the scope of protection of the present disclosure.

[0090] The present disclosure can also be expressed by the following points. It should be noted that, regardless of the dependent relationship between the points described below as examples, depending on any combination of elements of each of the described embodiments and modifications, elements of the points can be freely combined without contradicting each other. Point 1: Catheters, comprehensive: a shaft that is to be inserted into a body; a balloon that is attached to the shaft at a distal end and is expandable by a fluid supplied from one side of a proximal end of the shaft; a securing element that is wrapped around the outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon and is configured to limit the expansion of the balloon at the intermediate section; and a cover element that covers an outer circumference of the securing element. Point 2: Catheter according to point 1, wherein the securing element is elastically deformable in response to the expansion of the balloon. Point 3: Catheter according to point 1 or 2, wherein a secured diameter of the securing element is smaller than a maximum expansion diameter of the intermediate section of the balloon. Point 4: Catheter to one of points 1 to 3, wherein in a state where the pressure of the fluid is lower than a predetermined value, an expansion diameter of the locking element is at least 20% smaller than a maximum expansion diameter of the intermediate section of the balloon. Point 5: Catheter according to point 4, whereby the balloon can be expanded from a folded state to its maximum expansion diameter, according to the pressure of the fluid, the locking element is expandable beyond the secured diameter by being elastically deformed by the expanding balloon, and the cover element is expandable by being elastically deformed by the expanding balloon or the expanding locking element. Point 6: Catheter to one of points 1 to 5, wherein the securing element has a higher modulus of elasticity than the covering element. Point 7: Catheter according to point 6, wherein the balloon has a higher modulus of elasticity than the securing element. Point 8: Catheter to one of points 1 to 7, wherein the securing element is a ring-shaped element wrapped around the outer circumference of the intermediate section. Point 9: Catheter to one of points 1 to 8, wherein the securing element is a spiral element wrapped around the outer circumference of the intermediate section. Point 10: Catheter according to one of points 1 to 9, wherein the covering element covers a part of the outer circumference of the balloon around which the securing element is not wrapped, as well as the outer circumference of the securing element. Item 11: Catheter according to point 10, wherein the covering element covers part of the outer circumference of the shaft to which the balloon is not attached, as well as the outer circumference of the securing element and part of the outer circumference of the balloon. Point 12: Catheter to one of points 1 to 11, wherein the covering element is longer than the securing element in a direction connecting the distal end and the proximal end of the shaft. Point 13: Catheter according to point 12, wherein the covering element is longer than the balloon in the direction connecting the distal end and the proximal end of the shaft. Item 14: Catheter to one of points 1 to 13, wherein the length of the securing element in a direction connecting the distal end and the proximal end of the shaft is from 1 mm to 10 mm. Point 15: Catheter according to point 14, whereby the intermediate section of the balloon is a straight tube section with a maximum expansion diameter that is essentially uniform, a length of the straight tube section in the direction that the distal end and the proximal end of the shaft, which ranges from 10 mm to 40 mm. Item 16: Catheter to one of points 1 to 15, wherein the length of the intermediate section of the balloon is two to eight times longer than the length of the securing element in the direction connecting the distal end and the proximal end of the shaft. Item 17: Catheter according to one of points 1 to 16, wherein the cover element is attached to parts of the outer circumference of the catheter that are closer to a distal end and a proximal end than the securing element. Item 18: Catheter to one of points 1 to 17, wherein the securing element is not connected to either the balloon or the cover element. Item 19: Catheter according to any of points 1 to 18, wherein the covering element is a coating material that covers at least part of a boundary between the securing element and the outer circumference of the balloon. Item 20: Catheter according to point 19, wherein the coating material covers at least part of the boundary between the balloon and the distal end of the locking element and covers at least part of the boundary between the balloon and the proximal end of the securing element. Point 21: Catheter according to point 19 or 20, wherein the coating material is half the length or more of the locking element covers in the direction that connects the distal end and the proximal end of the shaft. Item 22: Catheter to one of points 19 to 21, wherein a variety of coating materials are provided at a variety of different positions in a circumferential direction of the locking element and the balloon while they are separated from each other. Item 23: A method for expanding a balloon in a catheter comprising a shaft to be inserted into a body, the balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft, a securing element wrapped around an outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon and configured to limit the expansion of the balloon in an intermediate section, and a covering element covering an outer circumference of the securing element, wherein the method comprises reducing, when the balloon together with the securing element and the covering element is expanded by supplying a fluid into the balloon, an expansion rate of the intermediate section around which the securing element is wrapped. Point 24: Catheters, comprehensive: a shaft that is to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a covering element that covers an outer circumference of the balloon and has a large thickness at an intermediate section between a distal end section and a proximal end section of the balloon compared to other sections. Point 25: Catheters, comprehensive: a shaft that is to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a visually detected section that is provided in an intermediate section between a distal end section and a proximal end section of the balloon and is visually distinguishable from other sections of the balloon. Item 26: Catheter according to point 25, further comprising a securing element wrapped around an outer circumference of the intermediate section and configured to limit the expansion of the balloon at the intermediate section, wherein The visually detected section is formed by the safety element, which is visually distinguishable from the balloon. Item 27: Catheter according to point 25 or 26, wherein the visually detected section differs from the other sections of the balloon in color and / or pattern. Item 28: Catheters, comprehensive: a shaft that is to be inserted into a body; and a balloon attached to the shaft at a distal end and enclosing a first balloon and a second balloon which is expandable by a fluid supplied from one side of a proximal end of the shaft, wherein the first balloon is provided closer to an outside in a direction of expansion than the second balloon and expands ahead of the second balloon. Item 29: Catheter after 28, with the first balloon being softer than the second balloon. Point 30: Catheter according to point 28 or 29, whereby the first balloon is expanded by the fluid into a constricted shape with a narrowed section in an intermediate section between a distal end section and a proximal end section of the balloon, and the second balloon is expanded by the fluid into a straight tube shape in the intermediate section. Item 31: Catheter according to point 30, wherein the constricted section of the first balloon, which has been expanded into the constricted shape by the fluid, is reduced by the second balloon, which is expanded by the fluid into the straight tube shape on the inside in the direction of expansion. Point 32: Catheters, comprehensive: a shaft that is to be inserted into a body; and a balloon attached to the shaft at a distal end, which is inflated by a fluid supplied from one side of a proximal end of the shaft, is extendable and includes an end-section securing structure which, after expansion into a narrowed form with a narrowed section in an intermediate section between a distal end section and a proximal end section, limits the expansion in the distal end section and the proximal end section. Point 33: Catheter according to point 32, wherein the end-section securing structure is formed by an end-section limiting element that is wrapped around an outer circumference of the distal end section and the proximal end section, and limits the expansion of the balloon at the distal end section and the proximal end section. Point 34: Catheter to point 32 or 33, wherein the end-section securing structure is formed by the distal end section and the proximal end section, which are harder than the intermediate section. Point 35: Catheters, comprehensive: a shaft that is to be inserted into a body; and a balloon attached to the shaft at a distal end, expandable by a fluid supplied from one side of a proximal end of the shaft, and incorporating a compression structure configured to cause an intermediate section between a distal end section and a proximal end section to compress before the distal end section and the proximal end section compress, at a time of compression when the fluid is released. Point 36: Catheter according to point 35, wherein the compression structure is formed by a securing element that is wrapped around an outer circumference of the intermediate section and has elasticity to limit the expansion of the balloon at the intermediate section. Point 37: A method for compressing a balloon of a catheter, which includes a shaft to be inserted into a body and the balloon attached to the shaft at a distal end, by means of a fluid supplied from one side of a proximal end of the shaft, is expandable and includes a compression structure configured to cause an intermediate section between a distal end section and a proximal end section to compress. before the distal end section and the proximal end section compress, at a time of compression when the fluid is drained, the method comprising increasing a compression rate of the intermediate section provided with the compression structure when compressing the balloon by draining the fluid in the balloon. Item 38: Catheters, comprehensive: a shaft that is to be inserted into a body; a balloon attached to the shaft at a distal end and expandable by a fluid supplied from one side of a proximal end of the shaft; and a securing element wrapped around an outer circumference of an intermediate section between a distal end section and a proximal end section of the balloon, configured to limit the expansion of the balloon at the intermediate section, and including a securing element release structure configured to release the securing element in at least one of a distal end section and a proximal end section of the securing element. Item 39: Catheter according to point 38, wherein the locking release structure is formed by a notch formed in at least one of the distal end section and the proximal end section of the locking element. Point 40: Catheter according to point 38 or 39, whereby the locking element includes a first locking element provided in at least one distal end section and a proximal end section of the locking element, and a second locking element provided in another section, and The safety release structure is formed by the first safety element with a lower securing force than the second safety element. List of reference symbols 1 balloon catheter 2 shaft 3 Balloon 3A First Balloon 3B Second Balloon 4 Elastic band 5 Cover element 6 guide wire 7 distributors 10 Endoscope 11 Tweezers canal 12 Camera 21 expansion fluid tubes 21A Balloon expansion lumen 21B Interior 22 guide wire tubes 22A wire lumens 31 Tapered section of the distal end 32 Intermediate section 33 Tapered section of the proximal end 41 Securing band of the distal end 42 Securing tape of the proximal end 43 ligament bodies 44 Distal end safety release structure 45 Proximal end fuse release structure 51 mounting tubes 52 mounting tubes 53 Coating material 71 Balloon expansion port 72 Guide wire connection 90 Duodenum 91 Papilla 92 Common bile duct 93 Pancreatic duct 211 First expansion fluid tube 211A First balloon expansion lumen 211B Interior 212 Second expansion fluid tube 212A Second Balloon Expansion Lumen 212B Interior 221 End of opening 222 contrast markers 223 contrast markers 311 Distal end section 321 Straight section of the distal end of the tube 322 Middle section 323 Straight tube section of the proximal end 331 Proximal terminal section

Claims

[1] Catheter, including: a shaft (2) that is to be inserted into a body; a balloon (3) which is attached to the shaft (2) at a distal end and is expandable by a fluid supplied from one side of a proximal end of the shaft (2); a securing element that is wrapped around the outer circumference of an intermediate section (32) between a distal end section and a proximal end section of the balloon (3) and is configured to limit the expansion of the balloon (3) at the intermediate section (32); and a cover element (5) that covers an outer circumference of the securing element, wherein an outer circumference of the locking element is not connected to an inner circumference of the cover element (5), and wherein a lubricant is arranged between the outer circumference of the locking element and the inner circumference of the cover element (5). [2] Catheter according to claim 1, wherein the locking element is elastically deformable in response to the expansion of the balloon (3). [3] Catheter according to claim 1 or 2, wherein a secured diameter of the securing element is smaller than a maximum expansion diameter of the intermediate section (32) of the balloon (3). [4] Catheter according to claim 3, wherein the balloon (3) can be expanded from a folded state to the maximum expansion diameter, according to the pressure of the fluid, the locking element is expandable beyond the secured diameter by being elastically deformed by the expanding balloon (3), and the cover element (5) is expandable by being elastically deformed by the expanding balloon (3) or the expanding securing element. [5] Catheter according to any one of claims 1 to 4, wherein in a state where the pressure of the fluid is lower than a predetermined value, an expansion diameter of the locking element is at least 20% smaller than a maximum expansion diameter of the intermediate section (32) of the balloon (3). [6] Catheter according to any one of claims 1 to 5, wherein the locking element has a higher modulus of elasticity than the cover element (5). [7] Catheter according to any one of claims 1 to 6, wherein the balloon (3) has a higher modulus of elasticity than the securing element. [8] Catheter according to any one of claims 1 to 7, wherein the securing element is an annular element that is wrapped around the outer circumference of the intermediate section (32). [9] Catheter according to any one of claims 1 to 8, wherein the securing element is a spiral element that is wound around the outer circumference of the intermediate section (32). [10] Catheter according to any one of claims 1 to 9, wherein the cover element (5) covers a part of an outer circumference of the balloon (3) around which the securing element is not wrapped, as well as the outer circumference of the securing element. [11] Catheter according to any one of claims 1 to 10, wherein the cover element (5) covers a part of an outer circumference of the shaft (2) to which the balloon (3) is not attached, as well as the outer circumference of the securing element and the part of the outer circumference of the balloon (3). [12] Catheter according to any one of claims 1 to 11, wherein the cover element (5) is longer than the locking element in a direction connecting the distal end and the proximal end of the shaft (2). [13] Catheter according to any one of claims 1 to 12, wherein the covering element (5) is longer than the balloon (3) in the direction connecting the distal end and the proximal end of the shaft (2). [14] Catheter according to any one of claims 1 to 13, wherein the length of the locking element in a direction connecting the distal end and the proximal end of the shaft (2) is from 1 mm to 10 mm. [15] Catheter according to any one of claims 1 to 14, wherein the intermediate section (32) of the balloon (3) is a straight tube section with a maximum expansion diameter that is essentially uniform, and the length of the straight tube section in the direction connecting the distal end and the proximal end of the shaft (2) is from 10 mm to 40 mm. [16] Catheter according to any one of claims 1 to 15, wherein the length of the intermediate section (32) of the balloon (3) in a direction connecting the distal end and the proximal end of the shaft (2) is two to eight times longer than the length of the securing element. [17] Catheter according to any one of claims 1 to 16, wherein the cover element (5) is fixed to parts of an outer circumference of the catheter that are closer to a distal end and a proximal end than the securing element. [18] Catheter according to any one of claims 1 to 17, wherein the securing element is not connected to either the balloon (3) or the cover element (5).

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