Patent Document

CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from U. S. Provisional Patent Application Ser. No. 60/751,865 filed Dec. 20, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to medical devices and more particularly to a cutting balloon device for expanding passageways in the venous system.  
       BACKGROUND OF THE INVENTION  
       [0003]     One of the most common heart diseases in industrialized countries is atherosclerotic cardiovascular disease, caused by the buildup of plaque or stenoses in the blood vessels. This affliction affects not only veins or arteries, but also dialysis access systems such as fistulas or grafts. Generally, arteries are susceptible to the buildup of plaque. The venous system, however, has lesions that are generally fibrous in nature, usually in the form of scar tissue or venous valvular rings. Additionally, when there is long term placement of a fistula or graft, there is a tendency for the passageway to narrow. The venous anastomosis of a graft, which may be made from PTFE or some other suitable material, may develop a different lesion, such as fibro-muscular hyperplasia. All three of these inflictions are distinct in their nature; however, they all generally respond well to balloon dilation or angioplasty.  
         [0004]     There are numerous inventions that have attempted to successfully expand venous passageways that have been narrowed by plaque or stenoses. One of the most well known is the “Fogarty catheter,” which is described in detail in U.S. Pat. No. 3,435,826 (the &#39;826 patent) to Fogarty, as well as U.S. Pat. No. 4,403,612 (the &#39;612 patent). Both the &#39;826 patent and the &#39;612 patent describe inflatable balloon catheters. The balloon catheter of the &#39;826 patent comprises a catheter having an inflatable balloon at its distal tip. The balloon catheter of the &#39;826 patent is operated by inserting the deflated balloon catheter into the vessel beyond the clogged portion, inflating the balloon and then pulling the inflated balloon towards the clogged area, thereby dislodging the clog and dragging the blockage to an incision where the clog can be removed. The balloon catheter of the &#39;612 patent has two balloons, wherein a first balloon is disposed inside of a second balloon and both the first and second balloon are located at the distal tip of a catheter. In use, the balloon catheter of the &#39;612 patent is inflated and compresses the plaque or stenoses that is located along the wall of a vessel, thereby enlarging the venous passageway.  
         [0005]     Most types of inflatable balloon catheters expand the vessel by exerting pressure on the buildup located on the walls of the vessel and squeezing the buildup against the vessel wall. There are other types of balloon catheters that do not inflate; rather, they expand using some other mechanical process. An example of this type of mechanically expanding balloon catheter is described in detail in U.S. Pat. No. 4,921,484 to Hillstead (the &#39;484 patent). The &#39;484 patent describes a catheter having a woven mesh balloon at its distal tip. During insertion, the balloon is elongated and maintains a narrow profile. When the balloon reaches the vessel to be expanded, the distal tip of the catheter is contracted, thereby expanding the woven mesh balloon. The expanded mesh balloon is then used to break through or scrape plaque and stenoses, thereby expanding the vessel.  
         [0006]     It would be beneficial to provide a device for removing plaque and stenoses from dialysis accesses such as fistulas or grafts, as well as blood vessels that may be clogged, that is inflatable through the injection of a fluid into the center of the balloon and also has the surface characteristics of a mesh balloon.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention is a cutting balloon catheter assembly including a dual lumen catheter having an inflatable balloon at its distal end having an interior cavity and an expandable covering disposed about the balloon, wherein the covering has an array of cutting edges. In the assembly, the balloon is fixedly connected to the distal end of the catheter and the interior cavity of the balloon is in fluid communication with an inflation/deflation lumen of the catheter.  
         [0008]     The invention further includes a method of removing obstructions from vessel walls using the cutting balloon catheter, wherein after catheter insertion and balloon inflation, the assembly is reciprocally moved either axially or rotationally, such that the array of cutting edges abrades the stenoses, plaque or lesions along the vessel wall. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings:  
         [0010]      FIG. 1  is a side view of a cutting balloon catheter assembly according to an embodiment of the present invention;  
         [0011]      FIG. 2  is an enlarged sectional view of the cutting balloon catheter assembly of  FIG. 1 , taken along line  2 - 2 , with the balloon inflated;  
         [0012]      FIG. 3  is an enlarged side view of a distal end of the cutting balloon catheter assembly of  FIG. 1 , in a deflated condition;  
         [0013]      FIG. 3   a  is an enlarged sectional view of an alternative embodiment of a cutting balloon catheter assembly;  
         [0014]      FIG. 4  is a sectional view of a hub of the catheter cutting balloon assembly of  FIG. 1 ;  
         [0015]      FIG. 5  is a side view, partially in section, of the distal end portion of the cutting balloon catheter assembly of  FIG. 1 , inserted into a patient&#39;s vessel and in an inflated condition; and  
         [0016]      FIG. 6  is a sectional view of the distal end portion of an alternative embodiment of the cutting balloon catheter assembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     In the drawings, like numerals indicate like elements throughout. Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The words “proximal” and “distal” refer to directions away from and closer to, respectively, the tip of the double lumen catheter assembly that makes up a portion of the cutting balloon assembly according to the present invention. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. The following describes preferred embodiments of the invention. However, it should be understood based on this disclosure, that the invention is not limited by the preferred embodiments described herein.  
         [0018]     Referring to  FIGS. 1 and 2 , a first preferred embodiment of a cutting balloon catheter assembly  100  according to the present invention is shown. Balloon assembly  100  is used to expand a patient&#39;s blood vessel by cutting blockages within the vessel. A blockage may be a lesion, stenoses, plaque or any other infliction that would constrict a patient&#39;s vessel. The balloon assembly  100  includes a balloon  110 , a mesh covering  120  and a catheter  130 . The catheter  130  comprises a proximal end  132 , a distal end  134  and a longitudinal axis  102  extending through the catheter  130  between the proximal end  132  and the distal end  134 . Preferably, the catheter  130  is a dual lumen coaxial catheter and has an interior wall  140  and an exterior wall  142 . In the preferred embodiment shown in  FIG. 2 , the catheter  130  has an axial lumen  136  located along the longitudinal axis  102 , and an exterior or inflation/deflation lumen  138  located about the axial lumen  136 . The axial lumen  136  is sized to accommodate a guidewire (see  FIG. 5 ) inserted therethrough along the longitudinal axis  102 . The axial lumen  136  is preferably defined entirely by the interior wall  140  . The exterior lumen  138  is defined by the exterior wall  142  and the interior wall  140 . While it is preferable, as shown in  FIG. 2 , that the axial lumen  136  be centered within the catheter  130  and entirely surrounded by the exterior lumen  138  (i.e., coaxial), those skilled in the art will recognize that the axial lumen  136  may be disposed anywhere within the exterior wall  142  of the catheter  130 .  
         [0019]     A distal tip  144  is located at the distal end  134  of the catheter  130 , at a point that is distal of the balloon  120 . Preferably, the distal tip  144  is rounded to facilitate smooth insertion of the assembly  100  into a patient&#39;s blood vessel. The distal tip  144  preferably is radiopaque for precision location at a site using known imaging techniques and has a distal passageway  146  that is in fluid communication with the axial lumen  136 , and provides a passageway between the axial lumen  136  and the outside of the distal tip  144 . The distal passageway  146  facilitates the insertion of the guidewire through the distal end  144  and the axial lumen  136 . Preferably, the catheter  130  is constructed of polyurethane or some other suitable biocompatible material.  
         [0020]     Referring to  FIGS. 2 and 3 , the balloon  110  is located proximate to the distal end  134  of the catheter  130 . The balloon  110  has a proximal balloon end  112 , a distal balloon end  114 , and an interior cavity  116  located between the proximal balloon end  112  and the distal balloon end  114 . Preferably, the balloon  110  is disposed circumferentially about the distal end  134  of the catheter  130  and is located proximally of the distal tip  144  of the catheter  130 . Preferably, the balloon  110  is constructed of polyurethane, silicone or some other suitable biocompatible material.  
         [0021]     The proximal balloon end  112  and the distal balloon end  114  are preferably fixedly attached to the exterior wall  142  of the catheter  130 , by bonding, adhesion, ultrasonic welding or any other attachment means that is suitable to fixedly attach the proximal balloon end  112  and the distal balloon end  114  to the exterior wall  142  of the catheter  130 . Preferably, the fixed attachment of the proximal and distal balloon ends  112 ,  114  to the catheter  130  forms a liquid-tight seal between the balloon  110  and the catheter  130 . Preferably, in its deflated state, as shown in  FIG. 3 , the balloon  110  is generally tubular in shape, extending between the proximal balloon end  112  and the distal balloon end  114 . As to size, the balloon could have a diameter of from 4 to 20 mm for use in the venous system, and of from 1.5 to 12 mm for use in the arterial system.  
         [0022]     Referring back to  FIGS. 2 and 3 , preferably the proximal balloon end  112  and the distal balloon end  114  are shaped to conform to the outside surface of the distal end  134  of the catheter  130 . In a case such as the present embodiment, wherein the catheter  130  is a co-axial catheter having a circular outer profile, the proximal and distal balloon ends  112 ,  114  would have circular profiles and be sized to fit about the exterior wall  142  of the catheter  130 . However, those skilled in the art will recognize that the catheter  130  and, correspondingly, the proximal and distal balloon ends  112 ,  114  may have any shape that facilitates the insertion and operation of the present invention.  
         [0023]     Referring now to  FIG. 2 , an inner surface  111  of the balloon and the exterior wall  142  of the catheter  130  define the interior cavity  116  that is in fluid communication with the exterior lumen  138  of the catheter  130 . At least one inflation port  148  is located in the exterior wall  142  of the catheter  130 . The at least one inflation port  148  is disposed through the exterior wall  142  of the catheter  130  in the portion of the catheter  130  that is located between the distal balloon end  112  and the proximal balloon end  114 . The inflation port  148  facilitates the inflation of the balloon  110  by allowing pressurized fluid to pass from the exterior lumen  138  into the interior cavity  116 , thereby expanding the balloon  110 .  
         [0024]     A covering  120 , having an outer surface  121  is disposed about and raised very slightly above the outside of the balloon  110  between a proximal covering end  122  and a distal covering end  124 . The covering  120  is preferably constructed of plastic or metal, and may be a mesh of flexible woven polyurethane fibers. However, the covering  120  may be constructed out of any other suitable material, as is known to those skilled in the art to define a covering that is flexible enough to expand when the balloon  110  is inflated and contract when the balloon  110  is deflated.  
         [0025]     The covering  120  may have a cross-hatched pattern, wherein the cutting edges are at substantially diagonal angles from the longitudinal and circumferential. Also, those skilled in the art will recognize that the covering  120  may have a longitudinal or a lateral pattern as well. The outer surface  121  of the covering  120  is preferably very sharp, thereby facilitating the laceration of lesions, stenoses or other intended materials within the vessel during use. Preferably, when the balloon  110  and the covering  120  are inflated, the fibers of the covering  120  will create an interlocking structure with an abrasive outer surface  121 , comprised of sharp individual fibers disposed together in a pattern about the outside of the balloon  110 .  
         [0026]     The covering  120  may be connected to the balloon  110  at one or more points, or alternatively, the covering  120  may be connected directly to the catheter  130  at one or more points. Alternatively, as shown in  FIG. 3   a , the covering  120  may be connected to the assembly  100  at one of the proximal and distal covering ends  122 ,  124 . The embodiment shown in  FIG. 3   a  is the same as the preferred embodiment except that in the alternative embodiment shown in  FIG. 3   a , a longitudinally translatable ring  126  is used to secure at least part of the covering  126  to the assembly  100  and is disposed at the other of the proximal and distal ends  122 ,  124  of the covering  120 . Regardless of how the covering  120  is connected to the assembly  100 , it is preferable that there is sufficient flexibility, between the covering  120  and the assembly  100 , to allow the balloon  110  to expand when inflated.  
         [0027]     Preferably, as shown in  FIG. 4 , the proximal end  132  of the catheter  130  comprises a hub  160  that is adapted to mate to the proximal end  132  of the catheter  110  so as to provide fluid communication between the axial lumen  136  and an axial port  162 , and between the exterior lumen  138  and an exterior port  164 . Preferably, the axial and exterior ports  162 ,  164  comprise luer fittings  166   a ,  166   b  respectively and are capped when the assembly  100  is not in use.  
         [0028]     The axial port  162 , which is in fluid communication with the axial lumen  136 , facilitates the insertion of a guidewire (see  FIG. 5 ) therethrough and comprises a valve  168  disposed therein. The valve  168  restricts the passage of blood, air or contaminants through the axial lumen  162  and is preferably a self sealing valve, and may be an elastomer made from silicone or some other suitable material, as is known to those skilled in the art.  
         [0029]     The exterior port  164  is in fluid communication with the exterior lumen  138 , and the luer fitting  166   b  of the exterior port  164  facilitates the connection of the exterior port  164  to an inflation device such as a syringe (not shown) or other suitable mechanical device (also not shown). Such mechanical devices may be an endoflator or other device known to those skilled in the art.  
         [0030]     Referring now to  FIGS. 2 and 5 , the cutting balloon assembly  100  may be used to break through the fibrous tissue  149  that comprises lesions within the venous system. The assembly  100  is also intended to be used in expanding a dialysis access, such as a fistula or graft. The cutting balloon assembly  100  may also be used to expand the interior walls of a patient&#39;s blood vessels that have been constricted with plaque and stenoses. It is preferable that, prior to insertion into the patient, the exterior lumen  138  of the catheter  130  and the interior cavity  116  of the balloon  110  are primed with a fluid, such as a saline solution. Also prior to insertion, it is preferable that exterior surface of the assembly  100  be lubricated with a saline solution or some other suitable lubricant.  
         [0031]     With reference to  FIG. 5 , in use a guidewire  150  having a distal tip  152  is inserted into a patient&#39;s blood vessel  154  using means known to those skilled in the art, far enough that the distal tip  152  extends past-the buildup of stenoses, plaque or lesions  149  within the vessel  154 . The cutting balloon catheter assembly  100  is then inserted into the patient&#39;s vessel  154  by inserting the proximal end (not shown) of the guidewire  150  into the distal passageway  146  of the distal tip  144  of the assembly  100 . The proximal end of the guidewire  150  is fed through the axial lumen  136  as the assembly  100  is slid distally along the guidewire  150  into the patient&#39;s vessel  154 . As the assembly  100  is slid distally along the guidewire  150 , the distal tip  144  of the assembly  100  enters the patient&#39;s blood vessel  154  first, followed by the balloon  110 ; and the assembly  100  continues to be slid along the guidewire  150  until the balloon  110  and the covering  120  are proximate to stenoses, plaque buildups or other lesions  149  inside of the patient&#39;s vessel  154 .  
         [0032]     Once the balloon  110  and mesh covering  120  are proximate to the stenoses, plaque or lesions  149  that are to be cut or expanded, the balloon  110  is inflated, by injecting fluid into the exterior lumen  138  of the catheter  130  through the exterior port  164 , shown in  FIG. 4 . Referring back to  FIGS. 2 and 5 , the balloon  110  is inflated to a size that is large enough to engage and create pressure on the stenoses, plaque or lesions along the interior walls of the patient&#39;s blood vessel  154 . Once the balloon  110  is sufficiently inflated, the assembly  100  may be rotated or translated longitudinally (axially), and reciprocally so moved, to help facilitate the mesh surface cutting the stenoses, plaque or lesions  149 . Rotating the assembly  100  about the longitudinal axis  102  is preferable when an embodiment of the covering  120  has laterally disposed cutting edges. Translating the assembly  100  back and forth in the proximal and distal directions along the longitudinal axis  102  is preferable when an embodiment of the covering  120  having longitudinally disposed cutting edges is used. In use, the cutting edges of covering  120  are intended to cut into stenoses, plaque or lesions  149  within the vessel  154 , there by allowing the vessel  154  to expand and facilitate an increased flow of blood therethrough. Rotating or twirling the assembly would not be suitable were the covering a mesh covering with cutting edges at angles substantially diagonal to the longitudinal and circumferential directions.  
         [0033]     Referring now to  FIG. 6 , an alternative embodiment of a cutting balloon catheter assembly  200  is shown. The alternative embodiment comprises a catheter  230 , with two lumens, having a side-by-side configuration rather than a coaxial design. The catheter  230  with a side-by-side configuration performs substantially the same function as the coaxial catheter  130  described above. In the side-by-side configuration, a first lumen  236  is adapted to be insertable into a patient&#39;s blood vessel, over a guidewire. A second lumen  238  is constructed as a fluid conduit for inflation of a balloon  210 . The second lumen  238  is in fluid communication with the balloon  210  through at least one inflation port  248 . Those skilled in the art will recognize that this alternative embodiment of the assembly  200  contains, with the exception of the catheter  230  configuration, substantially the same features as the preferred embodiment of the assembly  100 . Likewise, this alternative assembly  200  is operated in the same manner as the preferred embodiment  100 .  
         [0034]     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

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