Patent Document

FIELD OF THE INVENTION  
       [0001]     The present invention relates to methods, systems, and apparatus for deploying expandable medical implants. More particularly the present invention regards methods, systems, and apparatus that employ a curved wing balloon for deploying a medical implant at a target site.  
       BACKGROUND  
       [0002]     Expandable medical implants are positioned and placed in the body during the completion of numerous contemporary medical procedures. These implants may be used for innumerable purposes including physically reinforcing damaged vessels, replacing ruptured vessels, and delivering therapeutic to a target site in the body.  
         [0003]     These medical implants, which can include stents, are often delivered to their target site by an expandable balloon typically located at the distal end of a catheter. In use, when this balloon is positioned at the target site, a medical practitioner will direct fluid into the balloon to inflate the balloon and expand the implant. Then, once the implant has reached a desired size, it will be deployed from the balloon and the balloon will be removed from the target site.  
         [0004]     For numerous reasons these balloons are often folded so that they form wings or protrusions that unfold as they expand. While these wings or protrusions can provide the benefits of increased inflation speed and larger balloon size they can also impose unwanted uneven torsional forces on the implant during expansion thereby ripping or tearing away coatings resident on the implant. Both the coating damage and the twisting are undesirable because they can each compromise the effectiveness of the implant in its final deployed state.  
         [0005]     Various techniques for creating wings or protrusions and for folding the balloons are available. These techniques generally employ a forming stage and a tipping or folding stage, the forming stage involving the creation of one or more wings on the balloon and the tipping or folding stage involves tipping these protrusions over to wrap them around the balloon.  
         [0006]     Automatic cam-formers are available to form the protrusions, or wings, while the folding or tipping process is often a manual one, completed piecemeal by an operator. Hand-folding can be cumbersome and untenable as it requires a high degree of manual dexterity and is susceptible to randomly introducing foreign matter onto the surface of the balloon. Moreover, hand-folding is also inconsistent as its results vary from operator to operator.  
       SUMMARY OF THE INVENTION  
       [0007]     A curved-wing balloon is provided herein. A medical device embodying the invention may include an expandable balloon and an inner shaft positioned within the expandable balloon wherein the expandable balloon may be coupled to an inflation lumen, expandable from a first position to a second position, and having non-parallel sides when initially formed.  
         [0008]     A method employing the present invention may include placing an expandable medical balloon between a first forming blade and a second forming blade of a cam-former jaw system, moving the first forming blade from a first open position to a second closed position and moving the second forming blade from a first open position to a second closed position, the first forming blade having a first forming member, the second forming blade having a second forming member, the first forming member and the second forming member being in contact with the expandable balloon when in the second closed position, a mating surface of the first forming member being non-parallel to a mating surface of the second forming member when in contact with the balloon. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a cross-sectional view of an inflatable curved-wing balloon in accord with an embodiment of the present invention.  
         [0010]      FIG. 2  is a cross-sectional view of the curved-wing balloon of  FIG. 1  during inflation.  
         [0011]      FIG. 3  is a cross-sectional view of the curved-wing balloon of  FIG. 1  also during inflation.  
         [0012]      FIG. 4  is a cross-sectional view of the curved-wing balloon of  FIG. 1  in a fully inflated condition.  
         [0013]     FIGS.  5  a-d are sequential views of a process of forming a curved-wing balloon, in a cam-former, in accord with another embodiment of the present invention.  
         [0014]      FIG. 6  is a perspective view of a curved-wing balloon being drawn through a tipping or folding die and into a medical implant in accord with another alternative embodiment of the present invention  
         [0015]      FIG. 7  is a perspective view of a folded, curved-wing balloon inside a medical implant in accord with another alternative embodiment of the present invention.  
         [0016]      FIG. 8  shows a curved-wing balloon in a stent after the balloon has been fully expanded in accord with an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0017]      FIGS. 1-4  are cross-sectional views of an expandable curved-wing balloon, mounted on the distal end of a catheter, in various states of inflation in accord with an embodiment of the present invention. In this embodiment, the wings, or protrusions,  10  of the balloon  16  have been formed with a curved cross-sectional profile so that they may be more readily placed at or folded over to a non-radial angle from the central lumen as they are folded around the balloon  16 . The curved shape of the protrusions  10  may be imposed on them during their initial forming and at other suitable occasions during the manufacture and subsequent handling of the balloon  16 . In each of these circumstances, though, it is preferable that the curvature be added prior to the folding of the wings  10  around the balloon&#39;s central portion  19 .  
         [0018]     In one embodiment discussed in detail below, a cam-former is used to form the curved wings  10  of the balloon and an elongated tipping die is used to fold the wings  10  over around the balloon  16 .  
         [0019]      FIG. 1  shows a curved-wing balloon  16  in an uninflated condition in accord with an embodiment of the present invention. The curved-wing balloon  16 , which surrounds inner shaft  12  and internal lumen  2 , has a plurality of wings  10  that extend from its central portion  19 . The wings  10  in this embodiment have curved inner and outer walls  17  and  18 . These curved inner and outer walls  17  and  18  follow the same approximate rate of curvature as the central portion  19  of the balloon  16  in this embodiment, however, in other embodiments, the rate of curvature may be different—perhaps being more or less curved than the body of the balloon  19 . The balloon  16  in  FIG. 1  is shown in an uninflated state.  
         [0020]      FIG. 2  shows a partially inflated cross-section of the balloon  16  from  FIG. 1 . As can be seen in  FIG. 2 , the wings  10  of the balloon  16  begin to unwind in the direction of arrow  13  as fluid is injected into the balloon  16  from the lumen  2  to inflate the balloon. Thus, as can be seen in  FIG. 2 , the curved orientation of protrusions  10  not only provide them with a propensity to tip in the direction of arrow  1  when the balloon  16  is being folded but the curvature of the wings  10  may also influence the shape of the wings as they unfold in the direction of arrow  13 .  
         [0021]      FIG. 3  shows the balloon from  FIG. 2  after the protrusions  10  have been more fully inflated and have reached their fully extended position. In other words the tips of each of the wings are at their furthest point from the center of the balloon in  FIG. 3 .  
         [0022]     In  FIG. 3 , the predisposed curvature of the inner and outer walls  17  and  18  of the protrusions is prevalent. Moreover, as can be seen, as the wings  10  of this embodiment expand, rather than protruding linearly out from the central portion  19  of the balloon  16 , the protrusions have, instead, retained their curved orientation. As is also evident in  FIG. 3 , due to their uniquely formed shape, as the wings  10  inflate, their cross-sections may have a visible taper with the portion of the protrusion  10  closer to the central portion  19  of the balloon being wider than the rounded tip end  11  of the wing  10 .  
         [0023]      FIG. 4  is also a cross-sectional view of balloon  16 . In  FIG. 4 , balloon  16  is shown in its fully expanded state with the inner shaft  12  and internal lumen  2  being clearly shown in the center of the balloon  16 . However, while this inner shaft  12  and lumen  2  are shown in the center of the balloon in this embodiment they may also, in other embodiments, be located in other positions relative to the outside wall of the balloon.  
         [0024]     While a three wing balloon is provided and described in the embodiment of  FIGS. 1-4 , in alternative embodiments more or less protrusions may be used. Furthermore, the number of wings employed may depend upon the individual circumstances of the implant being deployed, the coating that may be resident on the implant, and any other number of factors. For instance, if the coating of the implant were susceptible to being rubbed off, the number of protrusions may be increased to reduce the amount of force placed on the coating by each of the wings  10  during expansion. Likewise, if the implant being deployed was easily damaged by concentrated forces placed thereon the number of protrusions could be increased to reduce the forces that it will place on the implant.  
         [0025]     Furthermore, while the wings  10  are illustrated as expanding in a clockwise direction in FIGS. nos.  1 - 4  they may also inflate in a counter-clockwise direction. Still further, in addition to being entirely concentric with the central portion  19  of the balloon  16 , a portion of the protrusions  10  may be curved outwardly, opposite the direction of curvature of the central portion  19  to accommodate a specific implant, a specific coating or some other specific design criteria.  
         [0026]      FIGS. 5   a - 5   d  are a series of illustrations showing the form stamping of a curved-wing balloon in accord with an alternative embodiment of the present invention. In  FIG. 5   a  an enlarged cross-sectional view of the forming blades  22  of a cam-former  20  are shown. As can be seen the forming blades  22  of the cam-former each has a profiled member  21  with curved mating faces  24 .  
         [0027]     In use, and as indicated by arrows  23 , these forming blades  22  slide within the cam-former  20  and may be used to form protrusions in a balloon  16 . Due to the shape of the profiled members  21  and mating faces  24 , three curved wings will be formed on the balloon  16   
         [0028]      FIG. 5   b  shows an initial step in the stamping or forming process of the balloon  16 . In  FIG. 5   b , the forming blades  22  are shown merging in on one another and interfacing with the balloon  16  to form the curved protrusions illustrated in  FIGS. 1-4 .  
         [0029]      FIG. 5   c  shows the forming blades  22  and their mating faces  24  of the cam-former  20  in their inner most position. The curved orientation of the mating faces of the profiled members  21  and the curved orientation of the wings  10  can be readily seen in this figure. During this step, as well as during others, heat and other formative influences may be used to facilitate the formation of the curved-wings  10 . In other words, the members  21  and their mating faces  24  may be heated to assist in setting the protrusions  10  during the stamping process. Alternatively, the members  21  may be cooled or various setting compounds may be interfaced with the balloon to set the curvature in the wings  10  during the stamping process. In each of these alternative embodiments, it is nevertheless preferred that some bias be introduced into the shape of the protrusions  10  so that the balloon wings do not become folds with parallel sides protruding orthogonally from the central axis of the balloon.  
         [0030]      FIG. 5   d  illustrates the members  21  moving away from each other in the direction of arrows  51  after the balloon  16  has been stamped and the protrusions  10  have been formed. As can be seen, after the stamping, the wings  10  of the balloon  16  have retained a curved non-parallel and non-planar profile. A profile that may facilitate the later wrapping or tipping of the protrusions around the balloon  16 .  
         [0031]     In this embodiment, the shape of the profiled member  21  and the mating faces  24  determined the profile of the wings  10 . As can be seen, this profile has an arcuate shape within the protrusions extending from the center of the balloon in a clockwise direction. As described below, this “pre-folded” form facilitates the actual folding or tipping of the wings, during later stages of manufacture.  
         [0032]     In an alternate embodiment, the balloon could be formed so that the protrusions are curved in a counter-clockwise direction. Likewise, different degrees of curvature may be chosen for different applications. Furthermore, during the manufacturing process when the wings  10  are formed and mating faces  24  are still pressed against the balloon  16 , a positive pressure may be applied to the folds while the blades  22  are retracted as shown in  FIG. 5   d.    
         [0033]     The forming blades  22  of the cam-former  20  may be made from any suitable rigid material and may be controlled by any suitable activation mechanism. It is preferred that the mating faces  24  be smooth and that their surfaces have non-adhesive properties so that they do not stick to the balloon  16  during stamping. Moreover, the forming blades  22  may be brought together for varying periods of time and under various pressures depending upon the properties of the balloon being stamped. Likewise, the distance between the mating faces  24  may be increased or decreased depending upon the thickness or other properties of the balloon being stamped.  
         [0034]     Once the balloon  16  has been stamped the protrusions  10  may be tipped back onto the balloon to prepare the balloon to receive the implant that it will carry.  
         [0035]      FIG. 6  shows a curved-wing balloon and a tipping die  60  in accord with an alternative embodiment of the present invention. In  FIG. 6 a  previously stamped curved-wing balloon  16  is shown being drawn through a tipping die  60  and into a medical implant  61 . As can be seen in  FIG. 6 , as the previously folded balloon is moved through the die  60 , due to the natural bias of the folds  10 , they may fold down upon themselves as the balloon  16  travels though the narrowing internal channel  62  of the die  60 . The die  60  in this embodiment may be heated while the balloon is being drawn through it to further heat-set the tipped protrusions of the balloon  16 . Alternatively, other external forces such as a vacuum and a positive pressure may also be placed on the balloon  16  to assist in tipping the wings  10 . For instance, a positive pressure may be applied between the internal channel  62  and the balloon  16  to allow for the proper tipping or wrapping of the protrusions  10  while a vacuum may be applied within the balloon  16  to draw the wings in as they pass through the die  60 .  
         [0036]     As can be seen in  FIG. 6 , the speed of the deployment process can be further increased, by positioning a medical implant  61  at the narrow end of the die  60  so that the tipped balloon is immediately drawn into the implant at the end of the tipping process. Once the implant has been placed over the tipped or folded balloon, it may then be crimped onto it. Alternatively, the balloon  16  may be moved through the die  60  and the implant may be placed onto it at a later date.  
         [0037]      FIG. 7  is a schematic of a curved-wing balloon  16  after it has been placed inside and crimped to a stent  71  in accord with an alternative embodiment of the present invention.  
         [0038]      FIG. 8  shows a curved-wing balloon  16  after it has been placed inside a stent  71  and fully expanded.  
         [0039]     The implant used in these various embodiments may be any one of numerous medical implants including a stent, an aneurism coil, a vena-cava filter, an a/v shunt, and a stent-graft. In some embodiments the implant may be coated with any one of the various available coatings. This coating may be used to carry or transport therapeutic, to facilitate the acceptance of the implant at the target site, to facilitate the rehabilitation of the target site, and to simply lubricate the folds as they unwind during inflation.  
         [0040]     While various embodiments of the present invention are disclosed above other embodiments are also plausible without straying from the spirit and scope of the present invention. For instance, while the tipping die is shown as a solid structure it may, instead, have a lattice wall thereby allowing various gases to be blown onto the balloon during the tipping and folding process.

Technology Category: 1