Balloon seal stress relief and related systems and methods of manufacture

Abstract

To provide devices, systems, and a method of production that reduce stress being exerted directly onto balloon seals.SOLUTION: The present disclosure is directed toward devices, systems and a method of production that reduce stress being exerted directly onto balloon seals (130) having a load sharing member (115) located at the shoulders between the seals (130) and the body portion (120) of a balloon (100).SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to reducing balloon seal stress to reduce the incidence of failures associated with balloon catheters. [Background technology]

[0002] Balloon catheters are often used in medical procedures to deploy endoprostheses. In a typical scenario, a balloon, secured to the catheter shaft by a seal, is hydraulically inflated to deploy the overlying endoprosthesis from a small delivery diameter to a larger working diameter. Balloons used in medical procedures such as percutaneous transluminal angioplasty (PTA) or localized drug delivery may require high balloon pressures, on the order of 10 to 30 atmospheres. Strengthening the balloon seal or reducing the stress on the seal to prevent or mitigate undesirable balloon failure can be beneficial, especially in high-pressure applications.

[0003] Additionally, reducing the amount of stress applied to the balloon seal can be particularly beneficial for expandable balloons constructed from materials that do not maintain a preformed or premolded shape upon inflation to the operating pressure range. However, these types of materials present challenges with the shape of the balloon's shoulder region upon inflation. For such balloons that utilize expandable materials in the shoulder region, the shape of the shoulder wall upon inflation is often considered to be less tapered in diameter between the working length and the seal, e.g., the shoulder is more vertical (right angle) or nearly vertical, or sometimes the opposite. This contrasts with balloons made from preformed or molded materials that are generally non-expandable (e.g., non-compliant), which upon inflation develop a shoulder wall shape that tapers from the end of the working length toward the balloon seal, e.g., a conical shape. A non-tapered shoulder can result in increased stress on the adjacent balloon seal. Balloon seals that have more "square" shoulders rather than conical shapes will withstand higher pressures at the seal, and balloons with such shoulder shapes can benefit from designs that reduce these seal pressures. Summary of the Invention

[0004] The balloons of the present disclosure have shoulder portions with load-distributing geometries, such as by adding load-distributing members.

[0005] According to one aspect of the disclosure, the balloon may include a body portion inflatable to a first diameter and including a wrapped polymeric material; two seal portions, each having a second diameter smaller than the first diameter; and two shoulder portions, each defining a transition between the first and second diameters, wherein at least one shoulder portion includes a load distribution member adapted to restrain inflation along at least a portion of the shoulder portion beyond a diameter between the first and second diameters. The body portion extends between the two shoulder portions, and the two shoulder portions and the body portion extend between the two seal portions.

[0006] According to another aspect of the invention, a balloon may include a body portion inflatable to a first diameter; two seal portions each having a second diameter smaller than the first diameter; and two shoulder portions each defining a transition between the first diameter and the second diameter, wherein at least one shoulder portion includes a stepped shape upon inflation of the balloon.

[0007] According to another aspect of the present invention, a method for reducing hoop stress on a seal portion on an expandable balloon having a body portion and two shoulder portions includes disposing a load distribution member around the balloon along at least a portion of at least one of the two shoulder portions, the balloon including a wrapped polymeric material.

[0008] Various aspects of the present disclosure may include various additional or alternative features in any combination. In various embodiments, the wrapped polymeric material may be an expanded fluoropolymer, such as expanded polytetrafluoroethylene. In various embodiments, the outer edge of the body portion and the inner edge of the seal portion may be longitudinally offset from one another. In various embodiments, the load distribution member may include a structural reinforcement member. In various embodiments, the load distribution member may extend along a substantial portion of the shoulder portion. In various embodiments, the shoulder portion may include a tapered shape. In various embodiments, the load distribution member may include a frusto-conical structural reinforcement member. In various embodiments, the load distribution member may be wrapped around a cone-shaped mandrel and may optionally include a densified or imbibed material. In various embodiments, the load distribution member may include a low expansion polymeric material molded into a tapered shape. In various embodiments, the shoulder portion may include a stepped shape. In various embodiments, the load distribution member may be isolated in an intermediate portion of the shoulder portion. In various embodiments, the load distribution member may comprise a material having a higher durometer than the wrapped polymer material. In various embodiments, the load distribution member may comprise at least one of densified ePTFE or imbibed ePTFE. In various embodiments, the load distribution member may comprise multiple wraps of a low-expansion polymeric membrane. In various embodiments, the load distribution member may be disposed on the exterior of the balloon body portion. In various embodiments, the load distribution member may comprise a pattern-cut reinforcing member, optionally Nitinol.

[0009] The accompanying drawings are included to provide a further understanding of the present disclosure, are incorporated into and constitute a part of this specification, illustrate embodiments of the present disclosure, and together with the description, serve to explain the principles of the present disclosure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a cross-sectional view of a balloon catheter with square shoulders.

[0011] [Figure 2A] FIG. 2A illustrates a cross-sectional view of a balloon catheter having a stepped shoulder configuration in accordance with the present disclosure.

[0012] [Figure 2B] FIG. 2B illustrates a cross-sectional view of a balloon catheter having a conical shoulder shape in accordance with the present disclosure.

[0013] [Figure 2C] FIG. 2C illustrates a cross-sectional view of another balloon catheter having a stepped shoulder configuration in accordance with the present disclosure.

[0014] [Figure 3] 3A-C illustrate an example of a balloon catheter according to the present disclosure inflated to a high pressure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Those skilled in the art will readily appreciate that various embodiments of the present disclosure can be realized by numerous methods and devices configured to perform the intended functions. In other words, other methods and devices can be incorporated into the present application to perform the intended functions. The accompanying drawings referenced in this application are not all drawn to scale and may be exaggerated to illustrate various embodiments of the present invention; in this regard, the drawings should not be considered limiting. Finally, while the present disclosure will be described in connection with various principles and beliefs, the present disclosure should not be bound by theory.

[0016] Generally, the present disclosure relates to devices, systems and methods for reducing direct stress on balloon seals. [Example]

[0017] With reference to FIG. 1 , the present disclosure includes a balloon 100. Generally, the balloon 100 includes a collapsed configuration and an expanded configuration. In the expanded configuration, the balloon 100 further includes shoulder portions 110 at each end of the balloon 100. The shoulder portions 110 are regions where the diameter of the balloon 100 transitions circumferentially between a larger diameter in the body portion or working length 120 of the balloon 100 and a smaller diameter in the sealing portion 130 of the balloon 100. As shown in FIG. 1 , these shoulder regions may assume a generally vertical and / or right-angled shape when inflated, rather than a tapered shape.

[0018] As illustrated, the sealing portion 130 generally functions to secure the balloon 100 about the catheter 140 and provide a fluid-tight interface between the balloon 100 and the catheter 140. The catheter 140 generally includes an inflation lumen and an outlet (not shown) for inflating the balloon with an inflation medium. In one embodiment, the sealing portion 130 includes a reinforcing feature, such as multiple wraps of a polymeric film having a polymer and / or adhesive imbibed or deposited on at least one surface or at least a portion of the film. For example, multiple wraps of ePTFE film at least partially imbibed with a cyanoacrylate can be used to form the seal reinforcement.

[0019] Balloon 100 further includes a balloon cover that covers a substantial portion of balloon 100. As used herein, references made to a "balloon" shall also be construed to include a "balloon cover," as the shapes and structural features described below apply to balloon covers in the same or similar manner as to balloons.

[0020] Balloon 100 comprises a compliant or quasi-compliant material or a material used to construct a balloon with limited expansion, such as a wrapped polymeric material. For example, balloon 100 comprises one or more fluoropolymers, such as expanded polytetrafluoroethylene ("ePTFE"), expanded modified PTFE, expanded copolymers of PTFE, expanded polyethylene, etc. In various embodiments, balloon 100 may include a helically, circumferentially, or axially oriented balloon wall, such as by wrapping an ePTFE film to form balloon 100. As used herein, the term "axial" is interchangeable with the term "longitudinal." As used herein, "circumferential" refers to an angle substantially perpendicular to the longitudinal axis. As used herein, "helical" refers to an angle that is neither parallel nor substantially perpendicular to the longitudinal axis. In various embodiments, a film is helically wrapped into a tubular shape to form a helically oriented balloon material. Orientation may refer to the direction of a particular property such as strength or microstructural features, for example, fine fibers.

[0021] Other materials with similar properties are within the scope of this disclosure. For example, balloon 100 may be made of amorphous general-purpose thermoplastic materials, including, for example, polymethyl methacrylate (PMMA or acrylic), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), modified polyethylene terephthalate glycol (PETG), cellulose acetate butyrate (CAB); semi-crystalline general-purpose plastics, including polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE or LLDPE), polypropylene (PP), polymethylpentene (PMP); polycarbonate (PC), polyphenylene oxide (PPO), modified polyphenylene oxide (Mod PPO), polyphenylene ether (PPE), modified polyphenylene ether (Mod PPO), or the like. Amorphous engineering thermoplastics, including PPE, and thermoplastic polyurethanes (TPU); semi-crystalline engineering thermoplastics, including polyamides (PA or nylons), polyoxymethylenes (POM or acetals), polyethylene terephthalate (PET, a thermoplastic polyester), polybutylene terephthalate (PBT, a thermoplastic polyester), and ultra-high molecular weight polyethylene (UHMW-PE); high-performance thermoplastics, including polyimides (PI, imidized plastics), polyamideimides (PAI, imidized plastics), and polybenzeneimidazoles (PBI, imidized plastics); polysulfones (PSU), polyetherimides (PEI), and polyethers The thermoplastics may be made from a variety of commonly known materials, such as amorphous high performance thermoplastics including polyarylsulfone (PES), polyarylsulfone (PAS); semi-crystalline high performance thermoplastics including polyphenylene sulfide (PPS), polyetheretherketone (PEEK); and semi-crystalline high performance thermoplastics including fluorinated ethylene propylene (FEP), ethylene chlorotrifluoroethylene (ECTFE), ethylene, ethylene tetrafluoroethylene (ETFE), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), fluoropolymers, etc.Other commonly known medical-grade materials include elastomeric organosilicon polymers, polyether block amides, or thermoplastic copolyethers (PEBAX). In addition, expandable balloons may be made from urethanes, silicones, fluoroelastomers, elastomers, and polyether block amides.

[0022] 2A-2C, in accordance with the present disclosure, shoulder portion 110 of balloon 100 may be inflated to include a load-distributing shape. Additionally, shoulder portion 110 of balloon 100 may include one or more load-distributing members that facilitate inflating to the load-distributing shape.

[0023] A load-distributing shape is generally any bulging shape of the shoulder portion 110 of the balloon 100 that relieves stress directly on the balloon seal. While not intending to be bound by theory, it is believed that circumferential and edge stresses are directly proportional to the balloon diameter adjacent the seal and therefore decrease as the diameter decreases gradually (e.g., in a ramped or curved manner) or in a stepped manner from the overall diameter to the seal diameter. In this regard, the balloon 100 may include an axis extending longitudinally, and the outer edge 121 of the body portion 120 and the inner edge 131 of the seal portion 130 may be longitudinally offset or spaced apart. More specifically, by non-limiting example, the load-distributing shape may include a stepped or conical shape.

[0024] For example, and as shown in Figures 2A and 2C, the stepped shape may include one or more circumferential steps 112 having a diameter intermediate between the larger diameter of the body portion 120 of the balloon 100 and the smaller diameter of the sealing portion 130 of the balloon 100. As illustrated, the steps 112 may include a circumferential ridge having a diameter smaller than the diameter of the body portion 120. The ridge may be oriented substantially parallel to the longitudinal axis. The stepped balloon shoulder 110 may include at least two portions adjacent the ridge that form an angle of approximately 90 degrees, although other angles greater or less than 90 degrees are within the scope of this disclosure.

[0025] 2B, the conical or tapered shape includes a circumferential taper 114 between the larger diameter of the body portion 120 of the balloon 100 and the smaller diameter of the sealing portion 130 of the balloon 100. As illustrated, the taper 114 subtends an angle of approximately 35-65 degrees, although angles greater than or less than the stated range are within the scope of the present disclosure.

[0026] Other shapes, such as shapes that include a curved transition between the larger diameter of the body portion 120 of the balloon 100 and the smaller diameter of the sealing portion 130 of the balloon 100, are also within the scope of the present disclosure.

[0027] In various embodiments, the load distribution geometry is provided at the shoulders of the balloon by one or more load distribution members, at least some of which are less distensible than the body portion. The less distensible load distribution members can include materials with a higher hardness or stiffness than the body portion material, materials and / or constructions that are less distensible than the body portion material or construction, or any material or construction that inhibits expansion of the shoulder portion beyond an intermediate diameter, i.e., a diameter between the larger diameter of the balloon's body portion and the smaller diameter of the balloon's seal. In various embodiments, the load distribution members are located outside the balloon's body portion or working length, e.g., in the portion intended to contact the luminal surface of the endoprosthesis and / or surrounding tissue, and are located away from the shoulder portion or extend only along a direction toward the balloon's seal.

[0028] In some embodiments, the load distribution member facilitates the load distribution shape but does not extend along a substantial portion of the shoulder 110; for example, the load distribution member is segmented along the middle of the shoulder. By way of non-limiting example, as shown in FIG. 2A, the load distribution member may include a band 113 that facilitates a circumferential step 112, creating a stepped shoulder shape. In other embodiments, the load distribution member extends along a substantial portion of the shoulder 110. For example, as shown in FIG. 2B, the load distribution member may include a frusto-cone 115 that extends along a substantial portion of the shoulder 110 so that the shoulder is conical or tapered in shape. Other shapes are also within the scope of this disclosure.

[0029] As shown in FIG. 2C, in other embodiments, the shoulder portion 110 may include multiple load distribution members, such as two or more bands 113.

[0030] In some embodiments, the load distribution element is a region of the balloon where the balloon material is deformed (e.g., a band or frustoconical region). An example of such a deformation is densification of the balloon material, e.g., ePTFE, along a targeted area of the shoulder. Such densification may be layered to create a tapered, load-distributing shape. In various embodiments, densification is achieved by applying pressure and / or localized heat (e.g., by sintering, laser processing, patterned laser processing, etc.) to a targeted area of the balloon material.

[0031] Another such variation involves coating or imbibing a generally low-expansion or non-expansive material (e.g., fluorinated ethylene propylene (FEP), PATT, thermoplastic materials, nylon, etc.) onto the targeted area of the balloon shoulder. For example, in an illustrative embodiment involving an ePTFE balloon material, imbibing involves at least partially filling the pores of the porous ePTFE at the targeted area with a generally low-expansion polymeric material.

[0032] In various embodiments, the shoulder portion may consist essentially of or consist of a second material having a higher hardness than the material of the body portion of the balloon, i.e., the material of the body portion is not continuous along the shoulder portion from the body portion to the seal, but may sandwich the second material at least in part along the shoulder portion.

[0033] In various embodiments, the load distribution members may be structural reinforcement members (e.g., having the shape of a band or a truncated cone) added to the balloon region. Such structural reinforcement members may be located between the balloon layers, between the balloon and balloon cover, on the surface of the balloon, and / or behind the balloon wall. Such structural reinforcement members may be adhered to the balloon / balloon cover (e.g., by heat treatment and / or the use of adhesives) or otherwise secured in place. According to aspects of such embodiments, the structural reinforcement members may include wrapped, molded, woven or knitted, die-cut or laser-cut, or other appropriately shaped reinforcement constructions.

[0034] For example, the structural reinforcement member may comprise a densified or imbibed material wrapped around an appropriately shaped mandrel as previously described.

[0035] For example, the structural reinforcement member may comprise a polymeric material of higher hardness than the main body portion that is molded (eg, blown or extruded) into an appropriate shape.

[0036] For example, the structural reinforcement member may include a pattern-cut reinforcement member or similar structure. The pattern-cut reinforcement member may include Nitinol or other similar shape-memory materials. For example, the Nitinol reinforcement member may include a collapsible annular member, like a stent ring, to facilitate a stepped configuration. Alternatively, the Nitinol reinforcement member may include, for example, an annular base that assumes a frusto-conical shape in the expanded state, which may be co-located with the seal and may be formed by having multiple Nitinol struts extending from the band to form a frusto-conical load-shaping shape when the balloon is inflated.

[0037] Thus, in accordance with the present disclosure, the load-distributing geometry reduces the stress directly placed on the balloon seal, thereby reducing the incidence of failures associated with balloon catheters.

[0038] Example of fabricating an ePTFE wrapped balloon cover including a stepped load-distributing geometry:

[0039] A stepped balloon is manufactured as follows: An ePTFE balloon cover (e.g., a cover comprising a wrapped ePTFE film) is placed on a mandrel at a first diameter (e.g., 8 millimeters) and narrowed or reduced in diameter to a neck portion having a neck diameter of approximately 0.070 inches (1.778 millimeters). The cover can then be expanded to approximately 4 millimeters and placed on a similarly sized mandrel. An anisotropic ePTFE film strip (approximately 5 mm wide) coated with a thermoplastic copolymer of tetrafluoroethylene and a perfluoroalkyl vinyl ether (described in U.S. Pat. No. 7,462,675, incorporated herein by reference in its entirety) can then be wrapped around the cover in the portion of the cover that will become part of the shoulder. The film can be wrapped at least twice so that the toughness direction of the film strip is oriented around the circumference of the balloon. The ePTFE film strip may be a 2-6 μm density strength ePTFE manufactured generally according to the teachings of U.S. Patent No. 7,521,010 to Kennedy, which is incorporated herein by reference in its entirety. The thickness of the copolymer coating may range from 1-3 μm. The cover portion, wrapped with a 5 mm ePTFE film strip, is heat treated after wrapping to bond the layers together and between the layers and the cover. The cover can then be placed over the balloon and secured to the catheter at each end.

[0040] The covered balloon can be inserted into a tube made of a material configured to shrink or contract at a particular temperature (e.g., FEP shrink tubing), and after the covered balloon is positioned, heated to about 260 degrees Celsius. The covered balloon can be reduced in diameter or size from a mid-diameter of 4 mm to about 0.100 inches (2.5 mm) using a radial crusher.

[0041] This allows the balloon to be fabricated with a stepped, load-shaping shape, as described above. Figures 3A-3C show such a covered balloon 300 inflated to increasing pressures of 14 to 24 atmospheres. As can be seen, at low pressures, the difference between the diameter of the balloon and the diameter of the circumferential step 312 of the main body portion 120 is smaller than at high pressures. However, even though the diameter of the main body of the balloon 300 is larger at high pressures, the circumferential step 312 cannot be inflated beyond its intermediate diameter.

[0042] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the present disclosure. Thus, the embodiments described herein are intended to cover the modifications and variations of the present disclosure provided they come within the scope of the appended claims and their equivalents.

[0043] The foregoing description sets forth numerous features and advantages, including various alternatives, together with details of the structure and function of the device and / or method. The disclosure is merely illustrative and is not intended to be exhaustive. It will be apparent to those skilled in the art that various modifications, including combinations within the principles of the invention, may be made, particularly with respect to structure, materials, elements, components, shapes, sizes, and arrangements of parts, to the full extent indicated by the broad and general meaning of the terms used in the claims. To the extent that these modifications do not depart from the spirit and scope of the claims, they are encompassed by the invention.

Claims

1. a body portion expandable to a first diameter; a first seal portion and a second seal portion, each having a second diameter smaller than the first diameter; and a first shoulder portion and a second shoulder portion, wherein the first shoulder portion and the second shoulder portion define a transition between the first diameter of the body portion and the second diameter of each of the first and second seal portions; A balloon comprising: both the first shoulder portion and the second shoulder portion include a load distribution member adapted to restrain each of the first shoulder portion and the second shoulder portion from expanding beyond a diameter between the first diameter and the second diameter; A balloon, wherein the load distribution member is continuous with the body portion and defines the body portion having a reduced distensibility compared to an intermediate portion of the body portion.

2. 10. The balloon of claim 1, wherein the load distribution member comprises at least one of a material that is harder or stiffer than the material of the body portion, a material that is less expansible than the material or construction of the body portion, a non-expandable material or construction, or any material or construction that inhibits inflation beyond an intermediate diameter between the first diameter and the second diameter.

3. The balloon of claim 1 or 2, wherein the load distribution member comprises a structural reinforcement member.

4. 4. The balloon of claim 3, wherein the structural reinforcement member is frusto-conical in shape.

5. The balloon of claim 3 , wherein the structural reinforcement member comprises a nitinol member.

6. The balloon of any one of claims 1 to 3, wherein an outer edge of the body portion and an inner edge of the first seal portion are offset in the longitudinal direction.

7. The balloon according to any one of claims 1 to 3, wherein the load distribution member is located only in the intermediate region of the first shoulder portion.

8. The balloon of any one of claims 1 to 3, wherein the load distribution member is extendable along at least a portion of the first shoulder portion.

9. The balloon of any one of claims 1 to 3, wherein the load distribution member is located outside the working length of the balloon and extends toward the first sealing portion.

10. The balloon of any one of claims 1 to 3, wherein an outer edge of the body portion and an inner edge of the first seal portion are offset in the longitudinal direction.

11. A balloon described in any one of claims 1 to 3, wherein the first shoulder portion includes a tapered shape including a circumferential taper between a first diameter of the main body portion and a second diameter of the first seal portion.

12. 4. The balloon of claim 1, wherein the first shoulder portion defines a curved transition between the first diameter of the body portion and the second diameter of the first seal portion.

13. 4. The balloon of claim 1, wherein the first shoulder portion defines a taper between the first diameter of the body portion and the second diameter of the first seal portion at an angle of about 35 to 65 degrees.

14. The balloon of claim 1 , wherein the first shoulder portion includes a plurality of load distribution members.

15. The balloon of claim 1 , wherein the body portion comprises a wrapped polymeric material.

16. 1. A method of manufacturing an expandable balloon having a body portion and two shoulder portions, wherein circumferential stress on a seal portion on the expandable balloon having a body portion and two shoulder portions is relieved, the method comprising: The method comprises: modifying the expandability of the body portion at a first shoulder portion to form a first load distribution member around the balloon along at least a portion of the first shoulder portion of the two shoulder portions; and modifying the expandability of the body portion at a second shoulder portion to form a second load distribution member around the balloon along at least a portion of the other of the two shoulder portions; The method, wherein the body portion comprises a wrapped polymeric material, at least a portion of the load distribution member is less distensible than the body portion, and at least one of the two shoulder portions comprises a sloped or stepped shape when the balloon is inflated.

17. 16. The method of claim 15, further comprising deforming the material of the load distribution member by densifying the material along a targeted area of at least one of the two shoulder portions.

18. 17. The method of claim 16, further comprising layering the densification of the load distribution member material to create a tapered shape.

19. 17. The method of claim 16, wherein densifying the load distribution member material further comprises applying at least one of pressure or localized heat to a target area.

20. 16. The method of claim 15, further comprising modifying the material of the load distribution member by coating or imbibing at least one of the two shoulder portions with a material that is less expansible than the body portion or that is not expansible at all.

Images