Abstract:
A system for treatment of a vessel lesion comprises an expandable balloon and at least one cutting string longitudinally engaged to an exterior surface of the balloon. When the balloon is in its expanded condition, a gap is formed between the at least one cutting string and the exterior surface of the balloon.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0002]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     Arterial blockages, which are also called stenosis, lesions, stenotic lesions, etc, are typically caused by the build-up of atherosclerotic plaque on the inside wall of an artery. In fact, several such stenoses may occur contiguously within a single artery. This can result in a partial, or even complete, blockage of the artery. As a result of the danger associated with such a blockage, several methods and procedures have been developed to treat stenoses. One such method is an angioplasty procedure which uses an inflatable balloon to dilate the blocked artery. A typical inflatable angioplasty device, for example, is disclosed in U.S. Pat. No. 4,896,669.  
         [0004]     Angioplasty balloons have enjoyed widespread acceptance in the treatment of stenoses. Recent studies, however, have indicated that the efficacy of the dilation of a stenosis is enhanced by first, or simultaneously, incising the material that is creating the stenosis. Consequently, developments have been made to equip angioplasty balloons with cutting edges, or atherotomes, which are intended to incise a stenosis during the dilation procedure. For example, U.S. Pat. No. 5,196,024, U.S. Pat. No. 5,616,149 and U.S. Pat. No. 5,797,935, the entire contents of each of which are incorporated herein by reference, describe inflatable angioplasty balloons having a number of atherotomes mounted longitudinally on the surface of the balloon. Upon inflation of the balloon, the atherotomes induce a series of longitudinal cuts into the surface of the stenotic material as the balloon expands to dilate the stenosis. As a result of such cuts, the stenosis is more easily dilated, and the likelihood of damaging the artery during dilation is reduced.  
         [0005]     Blades in many existing cutting balloon assemblies tend to be fairly rigid, particularly in the axial direction. The rigid axial structure of the blade naturally limits the blades ability to elongate with the underlying balloon material during balloon expansion at high pressure. As a result, stress between the comparatively axially rigid blade and the elongating balloon may lead to stress there between. The effect of balloon elongation is more pronounced in larger diameter balloons than in smaller diameter balloons, and is further amplified in longer balloon lengths as well.  
         [0006]     Existing blades also tend to be fairly rigid in the transverse direction as well. This has the affect of limiting the flexibility of the balloon as it is advanced through the tortuous confines of a vessel or other body lumen.  
         [0007]     In light of the above, it would be desirable to provide a cutting balloon that is more flexible and safer.  
         [0008]     All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.  
         [0009]     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.  
         [0010]     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.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention is directed to several embodiments. In at least one embodiment the invention is directed to a medical balloon for use with a catheter or similar device, wherein the medical balloon is equipped with at least one cutting string or a plurality of cutting strings longitudinally engaged to the medical balloon. The balloon is configured such that, when the medical balloon is in its nominal state, a gap is formed between the cutting strings and the exterior surface of the medical balloon.  
         [0012]     In some embodiments, the medical balloon has a varying cross-sectional shape and size along its length, such that two or more peaks are formed. Between the peaks, there is a circumferential trough which has an overall cross-sectional perimeter or shape which is less than that of the peaks. One or more cutting strings are engaged to the peaks and extend over the expanse formed by the trough, when the balloon is in its nominal condition.  
         [0013]     In some embodiments, the peaks and/or the entire balloon may have cross-sections which may take the form of any number of shapes, such as, but not limited to, round, ovoid, rectangular, triangular, and any combination thereof.  
         [0014]     In at least one embodiment, the circumferential trough portion of the balloon which forms the expanse between adjacent peaks may also take the form of any number of shapes, both in terms of its longitudinal cross-section and it circumferential cross-section..  
         [0015]     In other embodiments of the invention, three or more peaks may be provided, longitudinal spaced along the balloon and interspaced with corresponding circumferential troughs. The cutting strings may be engaged to two or more peaks and may extend from only one peak to an adjacent peak or they may extend up to and including the length of the balloon.  
         [0016]     In at least one embodiment one or more portions of the cutting string(s) that are in close proximity to the balloon surface are engaged to the balloon surface by an adhesive or other mounting material. The adhesive may be any adhesive material suitable for securing a metal, polymer or carbon based blade to the material of the balloon. Other bonding methods may be used, including, but not limited to, heat bonding, laser welding, RF bonding and hot jaw.  
         [0017]     As indicated above, a balloon may be equipped with any number of cutting strings, as desired. Multiple cutting strings may be uniformly or irregularly spaced apart.  
         [0018]     These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference should be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there is illustrated and described a embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0019]     A detailed description of the invention is hereafter described with specific reference being made to the drawings.  
         [0020]      FIG. 1  is a perspective view of an embodiment of the invention wherein a balloon is shown with multiple cutting strings.  
         [0021]      FIG. 2  is a perspective view of an embodiment of the invention wherein a balloon is shown with multiple cutting strings.  
         [0022]      FIG. 3  is a perspective view of an embodiment of the invention wherein a balloon is shown with multiple cutting strings.  
         [0023]      FIG. 4  is a perspective view of an embodiment of the invention wherein a balloon is shown with multiple cutting strings.  
         [0024]      FIG. 5  is a perspective view of an embodiment of the invention wherein a balloon is shown with multiple cutting strings.  
         [0025]      FIGS. 6   a - 6   c  show representative configurations of embodiments of the invention.  
         [0026]      FIG. 7  is a perspective view of an embodiment of the invention wherein a collapsed balloon is shown with multiple cutting strings.  
         [0027]      FIG. 8  is a cross-sectional view of the embodiment shown in  FIG. 7  along lines  8 - 8 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     While this invention may be embodied in many different forms, there are described in detail herein specific preferred 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.  
         [0029]     For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.  
         [0030]     As indicated above, the present invention is embodied in a variety of forms. In at least one embodiment, an example of which is depicted in  FIG. 1 , the invention is directed to a cutting balloon catheter, the distal end of which is generally shown at  10 . In this particular embodiment, a balloon  12  in mounted on distal end of a catheter shaft  14 . The balloon  12  has a proximal end cone  13  and a distal end cone  15 , proximal  21  and distal  23  waists, and, when in its nominal state, a varying radial cross-sectional shape along its length, forming at least two peaks  16 ,  18 . A peak is a portion of the balloon which has a greater cross-sectional shape, when the balloon is in its nominal state, than portions adjacently proximal and distal. The radial cross-sectional shapes of the peaks  16 ,  18 , are greater than that of a balloon portion  20 , positioned longitudinally there between.  
         [0031]     In the particular embodiment shown in  FIG. 1 , the radial cross-sectional shapes of the peaks  16 ,  18 , and the balloon portion  20  are rectangular in shape. However, it should be understood that the invention contemplates that the radial cross-sectional shape of the balloon may take the form of other shapes. In some instances, a balloon which takes the form of other shapes may be constructed such that, when fully pressurized, it takes on a round shape. The shapes illustrated in the figures demonstrate the shape of balloon when it is in its un-expanded or natural shape, which is their nominal or as-molded shape, which is the shape the balloon is molded to. When the balloon is expanded under pressurization, it takes on a round or rounder cross-sectional shape to form its expanded state.  
         [0032]     The embodiment shown in  FIG. 1  further includes a plurality of cutting strings  22 . These cutting strings  22  are engaged with the peaks  16 ,  18 , and are axially oriented relative to the balloon  12 . As shown, when the balloon  12  is in its nominal state, the cutting strings  22  are taught and straight and may be used to cut plaque or calcified lesions. Gaps  24  are formed between the cutting strings  22  and the balloon  12 , in this particular case, the balloon portion  20 .  
         [0033]     The cutting strings  22  are engaged with the peaks  16 ,  18 , of the balloon  12  in any of a variety of ways such as by mechanical engagement, direct welding, through the use of an adhesive, etc. In the embodiment shown, an adhesive material is used to engage the cutting strings  22  to the cross-sectional top surfaces  26  of the peaks  16 ,  18 , of the balloon  10 . Any suitable adhesive may be utilized as the adhesive material. For example, adhesives such as, but not limited to, epoxy, cyanoacrolyte, urethane and UV adhesives, etc. and/or combinations of such materials may by utilized as the adhesive material.  
         [0034]     In the particular embodiment shown in  FIG. 1 , as mentioned above, the peaks  16 ,  18 , have a rectangular radial cross-sectional shape. As shown, the cutting strings  22  are engaged with the cross-sectional corners  28  of the peaks  16 ,  18 . As shown, the comers  28  may be truncated so as to provide a flat surface to better receive the cutting strings  22 . In the embodiment shown, there are four cutting strings  22 . It should be understood that the cutting strings  22  may extend and be connected to or near the end cones  13 ,  15 . The ends of the cutting strings  22  may also be connected to the waists  21 ,  23 , of the balloon  12 .  
         [0035]      FIG. 2  illustrates a further embodiment. In this particular embodiment, the cutting strings are engaged with the top surfaces  26  of the peaks  16 ,  18 , at points  30  between the cross-sectional comers  28  of the peaks  16 ,  18 . Similarly, gaps  24  are formed between the cutting strings  22  and the circumferential trough  20 . In the embodiment shown, there are four cutting strings  22 .  
         [0036]      FIG. 3  illustrates a further embodiment of the invention. In this particular embodiment, the cutting strings are engaged with the top surfaces  26  of the peaks  16 ,  18 , at points  30  between the cross-sectional comers  28  of the peaks  16 ,  18 , and to the cross-sectional comers  28  of peaks  16 ,  18 . Similarly, gaps  24  are formed between the cutting strings  22  and the circumferential trough  20 . In the embodiment shown, there are eight cutting strings  22 .  
         [0037]      FIG. 4  illustrates a further embodiment of the invention. In this particular invention the radial cross-sectional shapes of the peaks  16 ,  18 , and the balloon portion  20  are circular or round in shape. The cutting strings  22  are similarly engaged to the top surfaces  26  of the peaks  16 ,  18 . Although the cutting strings  22  are shown to be parallel with the axis of the catheter shaft  14  in this and other embodiments, it should be understood that they may be positioned on a bias relative to the axis of the catheter shaft  14 . It should also be understood that the radial circumference, or cross-sectional shape, of the peaks  16 ,  18 , and circumferential trough  20  may take other shapes, such as, but not limited to, round, ovoid, rectangular, triangular, and any combination thereof.  
         [0038]     The circumferential troughs  20  shown in  FIGS. 1-4  have gradually decreasing radial cross-sectional shapes from respective peaks  16 ,  18 , to an intermediate point  34  to form sloping balloon walls  32 . However, it should be understood that the circumferential troughs  20  may take other forms. The form to be used provides an expanse between adjacent peaks, in this case peaks  16  and  18 , so as to create the gap  24  between the balloon  12  and the cutting wires  22 .  
         [0039]      FIG. 5  illustrates an alternative form of the circumferential trough  20 . In this embodiment the trough  20  provides an expanse between peaks  16  and  18  by including longitudinally shorter sloping balloon walls  32  and an elongated portion  36  of the balloon  12 , which has a relatively constant radial cross-sectional shape, there between. The gap  24  is similarly formed between the balloon  12  and the cutting strings  22 .  
         [0040]     As mentioned above, the shape of the circumferential trough  20  may vary in order to provide an expanse between the adjacent peaks. The number of longitudinal peaks and corresponding circumferential trough(s) may also vary.  FIGS. 6   a - 6   c  illustrates further balloon configurations. In these particular situations, the cuttings strings  22  may be connected to each peak they cross or just the most proximal and distal peaks. It should also be understood that the cutting strings  22  may be staggered on a balloon having three or more peaks, such as the one shown in  FIG. 6   a,  which is a four peak  100 ,  102 ,  104 ,  106 , balloon. For example, a cutting string may extend from the first peak  100  to the second peak  102 , another cutting string from the second peak  102  to the third peak  104  and another from the third peak  104  to the fourth peak  106 . The cutting strings may also be staggered relative to one another around the balloon.  
         [0041]     It should be understood that the present invention contemplates varying numbers of cutting strings  22  engaged at various positions on the balloon peaks  16 ,  18 .  
         [0042]      FIG. 7  is a illustration of the balloon of  FIGS. 1, 2 ,  4  and  5  in its collapsed and folded configuration.  FIG. 8  is a cross-section of the catheter of  FIG. 7  along lines  8 - 8 . As can be seen, the balloon is configured such that, when the balloon is collapsed, the portions of the peaks  40  of the balloon  12 , which are circumferentially between adjacent cutting strings  22 , fold over the cutting strings  22 , which may be held down with adhesive  46 , to cover them. Due to the decrease in the radial cross-sectional shape toward the middle of the balloon  42 , portions of the cutting strings are exposed. The folding may be induced by known methods, such as, but not limited to, memory inducement using ironing techniques.  
         [0043]     The cutting strings  22  are made of suitable material for cutting the particular obstruction within the target vessel. Such material includes, but is not limited to, one or more metals, polymers, suture strings or threads, combinations of one or more metals and/or polymers, and/or other desired material(s). If a soft material is used, the cross-sectional shape is of little matter, however, if a harder material, the cross-sectional shape may be, but not limited to, round, ovoid, ellipsoid, square, triangular, or any other geometric shape that may be desired. The cutting string  22 , regardless of its cross-sectional shape or shapes may be constructed by any of a variety of manufacturing methods. For example, the string  22  may be a wire constructed of metallic or other material wire stock. Other manufacturing techniques include photo-etching, laser cutting, waterjet cutting, or flat stock stamping of a desired blade material to form the cutting string  22 .  
         [0044]     In some embodiments, the cutting string  22  may include one or more areas, coatings, materials, etc. that is (are) detectable by imaging modalities such as X-Ray, MRI or ultrasound. In some embodiments at least a portion of the cutting string is at least partially radiopaque.  
         [0045]     While the embodiments shown in the figures have cutting strings  22  arranged in a symmetrical fashion about the balloon  12 , such symmetry need not be the case in all embodiments. In some embodiments, particularly the balloons that incorporate three or more peaks, the cutting strings may be of different or equal lengths; varyingly spaced apart, whether randomly or in accordance with a pattern; or otherwise arranged or positioned about the balloon in accordance with need, desire and/or performance.  
         [0046]     In at least one embodiment, the cutting strings  22 , and/or the balloon  12  may be configured to deliver one or more therapeutic agents to the lesion site. A therapeutic agent may be a drug or other pharmaceutical product such as non-genetic agents, genetic agents, cellular material, etc. Some examples of suitable non-genetic therapeutic agents include but are not limited to: anti-thrombogenic agents such as heparin, heparin derivatives, vascular cell growth promoters, growth factor inhibitors, Paclitaxel, etc. Where an agent includes a genetic therapeutic agent, such a genetic agent may include but is not limited to: DNA, RNA and their respective derivatives and/or components; hedgehog proteins, etc. Where a therapeutic agent includes cellular material, the cellular material may include but is not limited to: cells of human origin and/or non-human origin as well as their respective components and/or derivatives thereof. Where the therapeutic agent includes a polymer agent, the polymer agent may be a polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS), polyethylene oxide, silicone rubber and/or any other suitable substrate.  
         [0047]     The balloon  12  may be made of any suitable balloon material including compliant and non-compliant materials and combinations thereof. Some examples of suitable materials for constructing the balloon  10  include but are not limited to: low pressure, relatively soft or flexible polymeric materials, such as thermoplastic polymers, thermoplastic elastomers, polyethylene (high density, low density, intermediate density, linear low density), various co-polymers and blends of polyethylene, ionomers, polyesters, polyurethanes, polycarbonates, polyamides, poly-vinyl chloride, acrylonitrile-butadiene-styrene copolymers, polyether-polyester copolymers, and polyetherpolyamide copolymers; copolymer polyolefin material available from E.I. DuPont de Nemours and Co. (Wilmington, Del.), under the trade name Surlyn™; ionomer and a polyether block amide available under the trade name PEBAX™; high pressure polymeric materials, such as thermoplastic polymers and thermoset polymeric materials, poly(ethylene terephthalate) (commonly referred to as PET), polyimide, thermoplastic polyamide, polyamides, polyesters, polycarbonates, polyphenylene sulfides, polypropylene and rigid polyurethane; one or more liquid crystal polymers; and combinations of one or more of any of the above.  
         [0048]     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 claims where the term “comprising” means “including, but not limited to”. 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.  
         [0049]     Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.