Patent Publication Number: US-2007112300-A1

Title: Balloon folding design, apparatus and method of making the same

Description:
BACKGROUND OF THE INVENTION  
      Atherosclerotic cardiovascular disease is common, and is caused by a narrowing of the artery due to atherosclerotic plaques. Medical balloons are used in the body in a variety of applications including as dilatation devices for compressing plaque and for expanding prosthetic devices such as stents at a desired location in a bodily vessel.  
      Percutaneous transluminal angioplasty (including percutaneous transluminal coronary angioplasty (PTCA)), or balloon angioplasty, is a non-invasive, non-surgical means of treating peripheral and coronary arteries. This technique consists of inserting an uninflated balloon catheter into the affected artery. Dilation of the diseased segment of artery is accomplished by inflating the balloon which pushes the atherosclerotic lesion outward, thereby enlarging the arterial diameter.  
      Another type of medical balloon are those having cutting edges, also referred to as atherotomes or blades, for recanalizing and dilating a diseased vessel, and facilitating balloon angioplasty procedures. Balloons may also be equipped with injectors or other surface features as well.  
      For such applications, the balloon traverses a tortuous anatomy as it is being delivered to the location in a bodily vessel; it is desirable for the balloon to assume as low a profile, i.e. the outer diameter of the distal end portion of the balloon, as possible. Considerable effort has been put forth in the development of dilatation balloons with a low profile by, for example, minimizing the dimensions of the core or the inner tube which extends through the balloon to its distal end, and by reducing the wall thickness of the balloon itself.  
      The folding of medical balloons in order to reduce the cross sectional area or profile of the balloon in a deflated state of the balloon is a common industry practice. Balloons may also be folded in order to enhance re-fold characteristics of the balloon during deflation.  
      Folding of the balloon often involves formation of a number of wings in the balloon. In the deflated state, the balloon collapses upon itself forming flaps or wings that must be folded or wrapped about the balloon catheter to allow it to be withdrawn from the patient&#39;s vasculature after use.  
      Also prior to use, the balloon is typically folded or wrapped about the balloon catheter to fit within and pass through the guide catheter lumen. When inflation fluid is applied to the deflated balloon, the balloon wings or flaps unwrap or unfold and the balloon inflates to a fully expanded condition.  
      Various techniques or balloon constructions have been employed to facilitate the folding of the balloon about the balloon catheter in a uniform manner upon evacuation and deflation of the balloon after use.  
      There remains a need, however, for innovative and improved methods for folding balloons and for improved balloon refold. The present invention is directed to this need.  
      All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.  
      Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.  
      A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.  
     SUMMARY OF THE INVENTION  
      Embodiments of the present invention related to medical balloons which may be employed in combination with catheter assemblies for a variety of purposes such as for angioplasty, and for implantable medical device delivery such as stent delivery. Stents may be employed in the coronary arteries, peripheral vasculature, cerebrum, urethra, ureter, gastrointestinal tract, esophagus, urinary tract, bile ducts, alimentary tract, tracheobronchial tree, cerebral aqueducts, genitourinary system, prostatic urethra, fallopian tubes, as well as other regions of the body.  
      In at least one embodiment, a medical balloon having a body section, first and second tapered sections, and waist sections is formed such that in its static state, at least the body section has a plurality of concave side regions which extend between the first and second tapered sections. The concave side regions curve toward the longitudinal axis of the balloon. In one embodiment, the first and second tapered sections also have corresponding concave side regions.  
      In at least one embodiment, the concave side regions curve toward the longitudinal axis such that the center portion of the concave side regions is closest to the longitudinal axis.  
      In some embodiments the body section of the balloon further has a circumference which when viewed in radial cross-section, has at least one layer extending around the entire circumference which is formed from a homogeneous polymer material.  
      In some embodiments the balloon comprises multiple layers.  
      In at least one embodiment, in the expanded state, the body section of the balloon, as well as the tapered sections, may take on a substantially cylindrical configuration.  
      Embodiments of the invention are also directed to methods of making balloons.  
      In at least one embodiment, the balloon is formed in a mold form having an interior cavity respectively shaped to define corresponding portions of said balloon. The balloon exiting the mold form is in its static state.  
      In at least one embodiment, the balloon is formed in a mold form which is configured such that the mold cavity has a body section, first and second tapered sections, and waist sections, at least the body section has a plurality of concave side regions which extend between the first and second tapered sections. The concave side regions curve toward the longitudinal axis of the mold form. In one embodiment, the first and second tapered sections also have corresponding concave side regions.  
      The balloon can be deflated from a static state and folded. The balloon is particularly adapted for inflation from its folded configuration to an expanded configuration, and then deflated, and back to the folded configuration. The balloon according to the invention is designed for improved folding and refolding characteristics.  
      These and other aspects, embodiments and advantages of the present invention will be apparent to those of ordinary skill in the art upon review of the Detailed Description and Claims to follow.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of one embodiment of a balloon according to the invention shown in a static state.  
       FIG. 2  is a radial cross-section taken at section  2  in  FIG. 1  shown in a static state.  
       FIG. 3  is a radial cross-section of a balloon similar to that shown in  FIGS. 1 and 2  in a fully expanded state.  
       FIG. 4  is a radial cross-section of a balloon similar to that shown in  FIGS. 1 through 3  in a partially deflated state.  
       FIG. 5  is a radial cross-section of a balloon similar to that shown in  FIGS. 1 through 4  partially folded or wrapped.  
       FIG. 6  is a radial cross-section of a balloon similar to that shown in  FIGS. 1 through 5  in a folded or wrapped configuration.  
       FIG. 7  is a radial cross-section of another embodiment of a balloon according to the present invention further having atherotomes.  
       FIG. 8  is a radial cross-section of a balloon similar to that shown in  FIG. 7  in a partially deflated state.  
       FIG. 9  is a radial cross-section of another embodiment of a balloon according to the present invention further having drug delivery cones or injectors.  
       FIG. 10  is a radial cross-section of a balloon similar to that in  FIG. 9  in a partially deflated state.  
       FIG. 11  is a radial cross-section of a balloon similar to that in  FIGS. 9 and 10  in a folded or pleated state.  
       FIG. 12  is a perspective view of an alternative embodiment of a balloon according to the invention having three concave sides in a static state.  
       FIG. 13  is a radial cross-section taken at section  13  in  FIG. 12 .  
       FIG. 14  is a radial cross-section of a balloon similar to that in  FIGS. 12 and 13  in a partially deflated state.  
       FIG. 15  is a radial cross-section of a balloon similar to that shown in FIGS.  12  to  14 , in a partially folded or wrapped state.  
       FIG. 16  is a radial cross-section of a balloon similar to that shown in FIGS.  12  to  15  in a fully folded or wrapped state.  
       FIG. 17  is a radial cross-section of a balloon similar to that shown in FIGS.  12  to  16  in a fully expanded state.  
       FIG. 18  is a perspective view of one-half of a balloon mold.  
       FIG. 19  is a radial cross-section of one-half of a balloon mold taken at section  19  in  FIG. 18 .  
       FIG. 20  is a longitudinal cross-sectional view of an expandable medical balloon in combination with a catheter assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.  
      All published documents, including all US patent documents, mentioned anywhere in this application are hereby expressly incorporated herein by reference in their entirety. Any copending patent applications, mentioned anywhere in this application are also hereby expressly incorporated herein by reference in their entirety.  
      For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.  
      Depicted in the figures are various aspects of the invention. Elements depicted in one figure may be combined with, or substituted for, elements depicted in another figure as desired.  
      A medical balloon according to the present invention includes an inflation chamber formed by a balloon wall.  
      Turning now to the figures,  FIG. 1  represents medical balloon  10  according to the invention. Balloon  10  is adapted to be folded into a predetermined configuration. Balloon  10  is shown in  FIG. 1  in a static state. As used herein, the static state of the balloon shall refer to the balloon as formed such as immediately after removal from a mold after a blow molding process, for example, and prior to any deflation or inflation. Balloon  10  is shown having a plurality of concave side regions  15 . In this particular embodiment, balloon  10  is shown having 4 concave side regions  15  in a static state. Balloon  10  is also shown having waist  12 , cone regions  14  and body  16 . In this embodiment, cones  14 , in addition to body  16 , are shown having concave regions  17  located in cone regions  14 . One or more of these concave side regions are for facilitating balloon folding and refolding.  FIG. 2  is a radial cross-section of balloon  10  taken at section  2  in  FIG. 1 .  
      A balloon may be deflated from its static state, and folded or wrapped about the shaft of a catheter assembly (not shown).  
      Balloon  10  is adapted for inflation from a folded configuration to an inflated, expanded configuration and back to a folded configuration.  FIG. 3  is a radial cross-sectional view representing balloon  10  in an inflated state. Phantom lines indicate the balloon  10  in its static state prior to inflation.  
       FIG. 4  is a radial cross-sectional view representing balloon  10  in a partially deflated state, prior to folding. As can be seen from  FIG. 4 , balloon  10  in this partially deflated state, has four wings  20 .  FIG. 5  is a radial cross-sectional view representing balloon  10  in a partially folded or wrapped state, and  FIG. 6  is a radial cross-sectional view showing balloon  10  in a fully folded or wrapped state using methods known in the art.  
      In a typical folding procedure, the balloon may be placed in a folding apparatus, negative pressure applied, and the balloon manipulated with impinging members or blades from the folding apparatus into its folded or wrapped state.  
      After folding of the balloon, a balloon protector (not shown) may be added and the resultant assembly may then be sterilized.  
      Balloon  10  constructed and arranged similarly as those shown in FIGS.  1  to  6  above, is ideally suited for the addition of other features such as blades or atherotomes, for example.  FIG. 7  is a radial cross-sectional depiction of an alternative embodiment of a balloon  10  shown in a static state wherein atherotomes  22  have been added centrally to each of the concave side regions  15 . Such balloon designs can be employed for recanalization and dilation of diseased vessels, and for facilitating balloon angioplasty procedures. The balloons according to the invention may also be equipped with injectors or other surface features as well.  
       FIG. 8  is a radial cross-section showing a balloon  10  similar to that shown in  FIG. 7  in a partially deflated state, prior to folding.  
       FIG. 9  is a radial cross-section of an alternative embodiment of a balloon  10  shown in a static state. Balloon  10  is shown having drug delivery cones or injectors  24 . Drug delivery cones or injectors  24  are shown located centrally of concave side regions  15  of balloon  10 .  FIG. 10  is a radial cross-section showing a balloon  10  similar to that shown in  FIG. 9  in a partially deflated state, prior to folding.  
       FIG. 11  is a radial cross-section of a balloon similar to that in  FIGS. 9 and 10  in one embodiment of a folded or pleated state.  
       FIG. 12  is a perspective view of an alternative embodiment of balloon  10  shown having a plurality, in this embodiment three, of concave sides  15 .  FIG. 13  is a radial cross-sectional view of balloon  10  taken at section  13  in  FIG. 12 .  
       FIG. 14  is a radial cross-section of a balloon similar to that shown in  FIGS. 12 and 13  in a partially deflated state prior to folding or wrapping.  
       FIG. 15  is a radial cross-section of a balloon similar to that shown in FIGS.  12  to  14  in a partially deflated state and in a partially folded or wrapped state about catheter shaft while  FIG. 16  is a radial cross-section of a balloon similar to that in FIGS.  12  to  15  fully folded or wrapped around shaft.  
       FIG. 17  is a radial cross-section of a balloon similar to those shown in FIGS.  12  to  16  in a fully expanded state.  
      For any of the above embodiments, any suitable balloon folding apparatus may be employed herein. The above is only one exemplification of a balloon folding method and is not intended to limit the scope of the present invention. Balloon folding apparatuses and techniques are known in the art. For example, balloon folding apparatuses and methods thereof are discussed in commonly assigned co-pending U.S. Published Application Nos. 2003/0083687A1 and 2003/0163157A1, both of which are incorporated by reference herein in their entirety.  
      Other balloon folding apparatuses and methods thereof are described in U.S. Pat. No. 5,350,361, U.S. Pat. No. 6,126,652, US 2002/0163104A1, U.S. Pat. No. 6,033,380, to mention only a few, each of which is incorporated by reference herein in its entirety. The present invention is not limited by the type of balloon folding apparatus or method used therein.  
      Once folded, the present invention typically does not require heat setting of the balloon, although this step does not have to be excluded and in some embodiments it may be desirable to employ a heat set.  
      Balloon protectors or sleeves may be employed to keep the balloon folded prior to inflation and to help refold the balloon during and after deflation. One example is described in U.S. Pat. No. 6,071,285, which is incorporated by reference herein in its entirety.  
      The balloons according to the invention may be formed using any suitable polymer materials known in the art. Both thermoplastic and thermosetting materials may be employed. Both elastomeric and non-elastomeric polymer materials may be employed.  
      Examples of suitable polymer materials include, but are not limited to, polyolefins, polyesters, polyethers, polyimides, polyamides, ionomeric polymers, polyurethanes, polycarbonates, polyvinyl chlorides, polyphenylene sulfides, block copolymer elastomers, and so forth. Balloon formation using polyimides are disclosed in U.S. Pat. No. 6,024,722, the entire content of which is incorporated by reference herein.  
      Some classes of materials, such as the polyurethanes, are available in both thermoplastic and thermosetting forms, as well as elastomeric and non-elastomeric versions.  
      More specific examples of useful polyolefins include, but are not limited to, polyethylenes and polypropylenes and any copolymers thereof.  
      Other specific examples of materials useful in making the balloons of the present invention include, but are not limited to, polyethylene terephthalate, polybutylene terephthalate, acrylonitrile-butadiene-styrene copolymers, polyether-polyester copolymers, copolyesters, polyether polyamide copolymers, polyether block amides, and so on and so forth.  
      The balloons may be formed using any suitable balloon forming methods known in the art. An example of one method is described in U.S. Pat. No. 4,490,421 to Levy which is incorporated by reference herein in its entirety.  
      The methods typically include the basic steps of extruding a tubular parison, placing the tubular parison in a balloon mold, and expanding the tubular parison into the desired balloon configuration in the balloon mold.  
      One typical method of balloon manufacture, involves placing an extruded polymeric tube in the mold cavity, and radially expanding the tube such that it fills the mold cavity.  
      In one embodiment, the balloon, when viewed in radial cross-section, is formed from at least one layer of a homogeneous polymer material or a homogeneous blend of polymer materials, which is extruded into a tube, the tube place into a mold, and then formed into a balloon by radially expanding the tube into the mold.  
      As used herein, the term homogeneous shall be used to refer to a layer formed of a substantially uniform polymer composition.  
      A homogeneous layer may include fibers or particles mixed therein, providing that the fibers or particles are distributed substantially uniformly throughout the layer. For example, particles which are relatively small in size, for instance, those having a diameter of 1 micron or less, may be distributed therein.  
      A tube having multiple layers may also be employed. One method of forming a multilayer structure of this type is by coextrusion.  
      Furthermore, the tubular member may comprise fibers in the wall thereof, or fibers may be placed between a multilayer structure. Fibers may be in the form of a braid, weave, rove, web, etc., or may be randomly distributed in a homogeneous polymer layer as described above.  
      Any combination of such layers may be incorporated into the balloon structure, providing at least one layer is substantially homogeneous.  
      Desirably, the balloon is formed in a single molding step.  FIG. 18  is a perspective view of one-half of a mold form  30  for manufacturing a balloon having concave side regions according to the invention.  FIG. 19  is a radial cross-section taken at section  19  in  FIG. 18 . As can be seen from  FIGS. 18 and 19 , the mold form  30  is provided with the geometric configuration which is desired for the balloon in the static state, i.e. the state in which the balloon is released from the mold.  
      In the embodiment illustrated in  FIG. 18 , the mold cavity is shown having a central or body section  42 , and first and second tapered sections  44   a,    44   b  at either end of the central section  42 , and end or waist sections  46   a,    46   b  at either end of the tapered sections  44   a,    44   b.    
      Mold  30  has a plurality of concave side regions  45  extending at least along the central section  42  in a direction parallel to the longitudinal axis of the mold cavity, the concave regions  45  curving inward toward the longitudinal axis  48  of the mold  30 , such that, in this particular embodiment, the central part of the concave side region is closest to the longitudinal axis. In this embodiment, each half of mold is formed with a cavity having two concave side regions  45 . Please note, only one-half of the entire mold has been shown. The other half of the mold, would be a mirror image of the one shown in  FIG. 18 .  
      Concave side regions can be located in either or both of the tapered sections  44   a,    44   b  as well as in the central section  42  of the mold cavity. In the embodiment shown in  FIGS. 18 and 19 , alternatively, each tapered cone section  44   a,    44   b,  has a corresponding number of concave side regions  47  to the concave side regions  45  in the central section.  
      The outer wall of the resultant molded balloon is formed by (and corresponds to) the inner surface of the mold cavity. The resultant balloon will have a corresponding number of concave side regions to the entire mold cavity.  
      The balloon described above, is adapted for inflation from a folded configuration to an inflated, expanded configuration and back to a folded configuration. The concave side regions formed in the central section, and the tapered cone sections, facilitate folding and refolding of the expandable balloon member.  
      The balloons may further include partial or full coatings on the inner and/or outer walls. Examples of coating materials include, but are not limited to, those that provide lubricity, and those which may be included for purposes of drug delivery.  
      Any suitable lubricious material may be employed including both hydrophobic and hydrophilic lubricious materials. Examples of a hydrophobic lubricious material include, but are not limited to, silicone and fluoropolymers such as polytetrafluoroethylene.  
      Suitable examples of hydrophilic materials include, but are not limited to, polyalkylene oxides such as polyethylene oxide, polyvinyl pyrrolidone, polycarboxylic acids such as those based on maleic, fumaric or (meth)acrylic acid, for example.  
      Therapeutic agent(s) may be incorporated into a coating material, or other wise provided in combination with the balloons and catheter assemblies described herein. “Therapeutic agents,” “drugs,” “pharmaceutically active agents,” “pharmaceutically active materials,” and other related terms are employed in the art interchangeably. Hereinafter, the term therapeutic agent will be employed herein. Therapeutic agents include genetic materials, non-genetic materials, and cells. Of course mixtures of therapeutic agents may also be employed. Therapeutic agents are discussed in commonly assigned U.S. Patent Application 2004/0215169 and U.S. Pat. No. 6,855,770, each of which is incorporated by reference herein in its entirety.  
      Therapeutic agents may be incorporated into polymer coatings. Examples of suitable polymer coatings include both elastomeric and non-elastomeric polymer materials.  
      One suitable class of polymer coating materials includes block copolymer elastomers such as those having styrene end blocks. Examples include, but are not limited to, styrene-ethylene/propylene-styrene (SEPS), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene/butylene-styrene (SEBS), styrene-isobutylene-styrene (SIBS), and so forth. Such polymer materials are disclosed in commonly assigned U.S. Pat. Nos. 6,855,770 and 6,545,097, each of which is incorporated by reference herein in its entirety.  
      Other suitable polymer coating materials include, polyolefins, such as ethylene and propylene homopolymers, as well as any copolymers or terpolymers of ethylene and propylene such as ethylene-vinyl acetate copolymers, ethylene (meth)acrylate copolymers, ethylene n-butyl acrylate copolymers, and grafted polyolefins such as maleic anhydride grafted polyethylene or polypropylene.  
      Bioabsorbable polymers may also be employed as coating materials. Examples include, but are not limited to, poly(hydroxyvalerate), poly(L-lactic acid), polycaprolactone, poly(lactide-co-glycolide), poly(hydroxybutyrate), poly(hydroxybutyrate-co-valerate), polydioxanone, polyorthoesters, polyanhydrides, poly(glycolic acid), poly(D,L-lactic acid), poly(glycolic acid-co-trimethylene carbonate), polyphosphoesters, polyphosphoester urethanes, poly(amino acids), cyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate), copoly(ether-esters) (e.g. PEO/PLA), polyalkylene oxalates, polyphosphazenes and biomolecules such as fibrin, fibrinogen, cellulose, starch, collagen, hyaluronic acid, etc., and mixtures thereof. Bioabsorbable polymers are disclosed in U.S. Pat. No. 6,790,228, the entire content of which is incorporated by reference herein.  
      The therapeutic agents may be disposed within or under, the bioabsorbable polymer, for example.  
      The above lists are intended for illustrative purposes only, and are not intended to limit the scope of the present invention. Other materials not specifically listed herein, may be employed as well.  
      The balloons according to the present invention may be employed in combination with any suitable catheter assembly. Balloons are typically mounted on the distal end of the catheter assembly. For some catheter configurations known in the art, a dual shaft configuration including an inner shaft and an outer shaft is employed. An example of this type of catheter is shown as a longitudinal cross-sectional view in  FIG. 20 . The balloon is mounted at the distal end  24  of the catheter assembly  50  wherein the proximal end  26  of balloon  10  is mounted to the outer catheter shaft  32  and the distal end  28  of balloon  10  is mounted on the inner shaft  34 .  
      Such catheter assemblies may further include additional features as are known in the art including, but not limited to, implantable stents which are employed in various vessels in the body, drug delivery, perfusion and dilatation features, or any combination of such features may be used in combination with the dilatation balloon of the present invention.  
      In general, balloons in accordance with the present invention may be used in any and all vascular systems or cavities in the body. They may be employed in the implantation of stents in blood vessels which have collapsed, are partially occluded, blocked, weakened, or dilated for maintaining them in an open unobstructed state as well as for implanting stents in the urinary tract, bile ducts, alimentary tract, tracheobronchial tree, cerebral aqueducts, genitourinary system, prostatic urethra, fallopian tubes, as well as other regions of the body. The size of the stent as well as the balloon will depend on the application to which they are being put.  
      The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.