Abstract:
The present invention is directed to balloon folding configurations and methods for catheter devices having dual lumens in radial proximity to the balloon, such as, but not limited to, self-aligning stent delivery systems for treatment of bifurcated lesions. The configuration designs alters the conventional catheter profile by packing balloon materials in otherwise vacant areas located on both sides of the side branch shaft and/or the parent shaft, such that the device takes on more of a round profile instead of the classical elongated egg-shaped profile.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to balloon folding configurations for balloon catheter systems having distal dual lumens.  
       BACKGROUND OF THE INVENTION  
       [0002]     Percutaneous transluminal coronary angioplasty (PTCA) is a procedure that is well established for the treatment of blockages, lesions, stenosis, thrombus, etc. present in body lumens such as the coronary arteries and/or other vessels.  
         [0003]     A widely used form of percutaneous coronary angioplasty makes use of a dilatation balloon catheter, which is introduced into and advanced, through a lumen or body vessel until the distal end thereof is at a desired location in the vasculature. Once in position across an afflicted site, the expandable portion of the catheter, or balloon, is inflated to a predetermined size with a fluid at relatively high pressures. By doing so the vessel is dilated, thereby radially compressing the atherosclerotic plaque of any lesion present against the inside of the artery wall, and/or otherwise treating the afflicted area of the vessel. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patient&#39;s vasculature and blood flow resumed through the dilated artery.  
         [0004]     In angioplasty procedures of the kind described above, there may be restenosis of the artery, which either necessitates another angioplasty procedure, a surgical by-pass operation, or some method of repairing or strengthening the area. To reduce restenosis and strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, such as a stent, inside the artery at the lesion.  
         [0005]     Stents, grafts, stent-grafts, vena cava filters, expandable frameworks, and similar implantable medical devices, collectively referred to herein as stents, are radially expandable endoprostheses which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. Stents may be implanted in a variety of body lumens or vessels such as within the vascular system, urinary tracts, bile ducts, fallopian tubes, coronary vessels, secondary vessels, etc. They may be self-expanding, expanded by an internal radial force, such as when mounted on a balloon, or a combination of self-expanding and balloon expandable (hybrid expandable).  
         [0006]     Prior to delivery, a stent or stents may be retained on a portion of the delivery catheter by crimping the stent onto the catheter, retaining the stent in a reduced state about the catheter with a removable sheath, sleeve, sock or other member or members, or by any of a variety of retaining mechanisms or methods. Some examples of stent retaining mechanisms are described in U.S. Pat. No. 5,681,345; U.S. Pat. No. 5,788,707; U.S. Pat. No. 5,968,069; U.S. Pat. No. 6,066,155; U.S. Pat. No. 6,096,045; U.S. Pat. No. 6,221,097; U.S. Pat. No. 6,331,186; U.S. Pat. No. 6,342,066; U.S. Pat. No. 6,350,277; U.S. Pat. No. 6,443,880; and U.S. Pat. No. 6,478,814.  
         [0007]     Bodily vessels that branch off into further vessels are termed bifurcated vessels. Some bifurcated vessels have stenotic lesions and disease requiring treatment of the parent vessel, while preserving access to the side branch vessel. A dual lumen catheter system used to stent a bifurcation site allows the physician to maintain guide wires in both the parent and side branch vessels. These guide wires can then allow post dilation balloons to be guided into the bifurcation through a deployed stent. In a dual lumen device, the stent cell that the side branch lumen penetrates aligns itself into the side branch vessel. Proper alignment assures that the carina gets good stent coverage and that the stent does not obstruct the side branch vessel.  
         [0008]     A stent delivery system employing a stent assembly with branches intended for deployment in adjacent branches of a vessel bifurcation allows placement of a portion of the assembly in both a primary passage, such as an artery, and a secondary passage, such as a side branch artery. Additionally, these stents generally have an opening that allows for unimpeded blood flow into the side branch artery. However, due to use of two separate lumens, the resulting profile is increased and the cross-section takes on an oval shape, reducing stent contact and ease of stent rotation.  
         [0009]     Thus, a need exists to provide a catheter that is capable of allowing a medical device, such as a stent, to be easily maneuvered and aligned at a vessel bifurcation or other location. Various devices and methods described herein address these issues by providing a catheter system with inventive balloon folding designs.  
         [0010]     All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.  
         [0011]     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.  
         [0012]     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  
       [0013]     The present invention is directed to stent delivery systems having unique balloon configurations and methods for catheter devices having dual lumens in radial proximity to the balloon, such as, but not limited to, self-aligning stent delivery systems for treatment of bifurcated lesions. The configuration designs alter the conventional catheter profile by packing balloon materials in otherwise vacant areas located on both sides of the side branch shaft and/or the parent shaft, such that the device takes on more of a round profile instead of the classical elongated egg-shaped profile. With the round profile, the stent achieves more uniform deployment characteristics and decreases the resistance of the device when rotating in the vessel. Decreasing the resistance to rotate the stent into alignment allows the device to align with less input force from the physician.  
         [0014]     In at least some embodiments, the round profile also enhances stent securement. With a round profile, one may better utilize crimping processes without worry about major and minor axis crimp force applied. Crimp head elements of conventional crimpers can close on a round profile uniformly, thus maximizing stent strut contact with the balloon material. Furthermore, in embodiments where the balloon folds surround the side branch shaft, the crimped stent makes contact with balloon material all the way around creating a pillowing effect for increased securement.  
         [0015]     The folding configurations of the present invention also accommodate radial alignment of the distal end of the catheter due to the presence of balloon material between the crimped stent and the side branch shaft. A radially aligned side branch shaft is parallel to the parent shaft and properly positioned relative to the stent so as to extend through the stent into a side branch vessel. Additional stiffness transition can also be provided at the side branch shaft exit location. Balloon folds create walls on either side of the side branch shaft limiting the side-to-side motion of the side branch. Limiting side-to-side motion allows for an increase in torque transmission to align the stent with the side branch vessel.  
         [0016]     In at least one embodiment, the stent-receiving region of a stent delivery system of the present invention comprises a parent shaft and a side branch shaft aligned in parallel fashion and a stent mounted there about. A balloon is mounted about the parent shaft and is positioned between the two shafts. When the balloon is in its delivery configuration, it comprises at least two inward wing folds extending from the central body of the balloon. The two wing folds are inwardly wrapped on both sides of the side branch shaft.  
         [0017]     In at least one embodiment, the stent-receiving region of a stent delivery system of the present invention comprises a parent shaft and a side branch shaft aligned in parallel fashion and a stent mounted there about. A balloon is mounted about the parent shaft and is positioned between the two shafts. When the balloon is in its delivery configuration, it comprises two outward wing folds extending from the central body of the balloon. The two wing folds are outwardly wrapped on both sides of the side branch shaft.  
         [0018]     In at least one embodiment, the stent-receiving region of a stent delivery system of the present invention comprises a parent shaft and a side branch shaft aligned in parallel fashion and a stent mounted there about. A balloon is mounted about the parent shaft and is positioned between the two shafts. When the balloon is in its delivery configuration, it comprises two inward wing folds extending from the central body of the balloon. The two wing folds are inwardly wrapped over the side branch shaft in overlapping fashion.  
         [0019]     In at least one embodiment, the stent-receiving region of a stent delivery system of the present invention comprises a parent shaft and a side branch shaft aligned in parallel fashion and a stent mounted there about. A balloon is mounted about the parent shaft and at least a portion is positioned between the two shafts. When the balloon is in its delivery configuration, it comprises three inward wing folds extending from the central body of the balloon. Two wing folds are inwardly wrapped on both sides of the side branch shaft. The third wing is formed at the six-o&#39;clock orientation (from a cross-sectional view prospective, wherein the side branch shaft is in the twelve-o&#39;clock position relative the parent shaft). It should be understood that more than three wing folds may be employed at varying positions around the parent shaft.  
         [0020]     In at least one embodiment, the stent-receiving region of a stent delivery system of the present invention comprises a parent shaft and a side branch shaft aligned in parallel fashion and a stent mounted there about. A balloon is mounted about the parent shaft and at least a portion is positioned between the two shafts. When the balloon is in its delivery configuration, it comprises three outward wing folds extending from the central body of the balloon. Two wing folds are outwardly wrapped on both sides of the side branch shaft. The third wing is formed at the six-o&#39;clock orientation (from a cross-sectional view prospective, wherein the side branch shaft is in the twelve-o&#39;clock position relative the parent shaft). It should be understood that more than three wing folds may be employed at varying positions around the parent shaft.  
         [0021]     These and other embodiments that 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 are illustrated and described embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0022]     A detailed description of the invention is hereafter described with specific reference being made to the drawings.  
         [0023]      FIG. 1  is a side view of a dual lumen stent delivery system.  
         [0024]      FIG. 2  is a side perspective view of a stent, such as that shown in  FIG. 1 .  
         [0025]      FIG. 3  is a side perspective view of the stent shown in  FIG. 2 , wherein a side branch opening is shown formed.  
         [0026]      FIG. 4  is a cross-sectional view of the stent of  FIG. 3 .  
         [0027]      FIG. 5  is a side view of a stent delivery catheter within a bifurcated vessel.  
         [0028]      FIG. 6  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0029]      FIG. 7  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0030]      FIG. 8  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0031]      FIG. 9  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0032]      FIG. 10  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0033]      FIG. 11  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 .  
         [0034]      FIG. 12  is a cross-sectional view of an embodiment of the catheter shown in  FIG. 1  along lines  100 - 100 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]     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.  
         [0036]     For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.  
         [0037]     Referring now to the drawings, which are for the purposes of illustrating embodiments of the invention only and not for purposes of limiting same,  FIG. 1  illustrates a dual lumen stent delivery system  10 . This illustrative representation is being used to generally refer to bifurcated systems having dual lumens for dual guide wires, a primary guidewire  22  and a secondary guidewire  24 , for accessing bifurcated vessels. Examples of bifurcated systems include, but are not limited to, those shown and described in U.S. patent application Ser. No. 10/375,689, filed Feb. 27, 2003 and U.S. patent application Ser. No. 10/657,472, filed Sep. 8, 2003, both of which are entitled Rotating Balloon Expandable Sheath Bifurcation Delivery; U.S. patent application Ser. No. 10/747,546 Dec. 29, 2003 and entitled Rotating Balloon Expandable Sheath Bifurcation Delivery System; and U.S. patent application Ser. No. 10/757,646, filed Jan. 13, 2004 and entitled Bifurcated Stent Delivery System, the entire content of each being incorporated herein by reference.  
         [0038]     The inventive system  10  includes a catheter  12  having a balloon  14  mounted on the distal end  16 . At the distal end  16  end of the catheter, there are two radially adjacent shafts  18 ,  20 . As shown in  FIG. 1 , the balloon  14  is mounted on shaft  18 , which is the parent shaft. Shaft  18  defines a lumen, which houses a primary guide wire  22 . Branching off of the parent shaft  18  or at some other position on the catheter  12  is a side branch shaft  20 . Side branch shaft  20  also defines a lumen, which houses a second or secondary guide wire  24 . The construction and use of such dual lumen catheters are well known to those skilled in the art of catheter design and use.  
         [0039]     As shown in  FIG. 1 , a stent  26  is mounted onto the balloon  14  and parent shaft  18  and onto the side branch shaft  20 . Stent  26  may be a stent, such as is shown in  FIG. 2 , which is at least partially constructed of a plurality of interconnected struts, connectors or members  132 . The stent  132  defines a proximal opening  134 , a distal opening  136  and a flow path  138  there between. The cell openings  130  are in fluid communication with the flow path  138 .  
         [0040]     When the secondary guidewire  24  and/or the side branch shaft  20  is threaded through one of the cell openings  130  when the stent is positioned onto the assembly  10 , such as is shown in  FIG. 1 , the members  132  that define the selected cell opening  130   a , as well as the shape of the opening  130   a  through which the secondary guidewire  24  exits the stent, may be distorted or modified in order to accommodate the passage of secondary guidewire  24  and/or the side branch shaft  20  there through.  
         [0041]     The modified cell opening  130   a , hereinafter referred to as secondary opening  130   a , is positioned on the stent  26  between the proximal opening  134  and the distal opening  136 . The manner in which the secondary opening  130   a , the members  132  adjacent thereto, and to an extent the stent  26  itself, are modified or distorted by the position of the secondary guidewire  24  and/or side branch shaft  20  is depicted in  FIGS. 3 and 4 .  
         [0042]     It should be noted that when the stent  26  is placed on the assembly in the manner described above, the distortion of the secondary opening  130   a  and the adjacent members  132  is of a minimal extent, and is provide only to allow sliding passage of the secondary guidewire  24 , and if desired a distal portion of the side branch shaft  20 , through the secondary opening  130   a . As such, the actual size of the secondary opening  130   a  may be substantially similar, or only marginally different than that of the surrounding cell openings  130 .  
         [0043]     It should also be further noted that while stent  26  may be a standard “single vessel” stent that is provided with a secondary opening  130   a  in the manner described above, the stent  26  may also be a bifurcated stent having a trunk or stem portion, with one or more leg portions and/or branch openings adjacent thereto, through one of which the secondary guidewire may be passed. Such bifurcated stents and stent assemblies are well known in the art.  
         [0044]     In some cases, the stent  26  may be configured to deliver one or more therapeutic agents to a delivery site such as within the vessel or one or more areas adjacent thereto. To better accommodate placement of a therapeutic agent on the stent  26 , in some instances one or more stent members  132 , such as is shown in  FIG. 2 , maybe configured to include one or more holes, notches, or other surface features to which one or more therapeutic agents  400  may be placed for delivery to the aneurysm site. A therapeutic agent may be placed on the stent in the form of a coating. Often the coating includes at least one therapeutic agent and at least one polymer.  
         [0045]     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 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 agent may be a polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS), polyethylene oxide, silicone rubber and/or any other suitable substrate.  
         [0046]     As shown in  FIG. 5 , in use, the catheter  12  is inserted into a vessel  30  and advanced along the primary guide wire  22  to a portion  31  of the vessel  30 , which is bifurcated. The end  33  of the side branch shaft  24  is positioned at the opening of the branching vessel  32  so that the secondary guide wire  24  may be advanced into the branching vessel  32 . In some bifurcation systems, including, but not limited to, the system described in U.S. patent application Ser. No. 10/863,724, titled BIFURCATED STENT DELIVERY SYSTEM, which is incorporated herein by reference in its entirety, as the system is advanced along both guidewires  22  and  24 , as a result of the divergent paths defined by the guidewires  22  and  24 , the stent  26  is moved into a desired position so that the secondary opening  130   a  of the stent is aligned with the secondary passage  35 .  
         [0047]      FIGS. 6-12  are illustrations of various configurations of the invention. The figures show cross-sectional views of the system  10  shown in  FIG. 1  along lines  100 - 100 . The illustrations show the folding and positioning of the balloon  14  relative to the parent shaft  18 , the side branch shaft  20  and the stent  26 , when the balloon  14  and stent  26  are in their delivery configuration during placement of the catheter. The folds extend along the length of the balloon  14 . The illustrations are illustrative and aren&#39;t meant to be to scale. Techniques for folding balloons are well known and therefore are not discussed herein.  
         [0048]     In the embodiment shown in  FIG. 6 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that two wing folds  50 ,  52 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  84 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  50 ,  52 , axially extend along the length of the balloon  14 . The wing folds  50 ,  52 , are folded such that they are wrapped inward and extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20 . The ends  54 ,  56 , of the wing folds  50 ,  52 , may extend up to the sides of the side branch shaft  20  or they may extend up and over the side branch shaft  20 , such that the ends  54 ,  56 , are in immediate proximity, up to the point of touching each other.  
         [0049]     In the embodiment shown in  FIG. 7 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that three wing folds  58 ,  60 ,  62 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  84 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  58 ,  60 ,  62 , axially extend along the length of the balloon  14 . The wing folds  58 ,  60 , are folded such that they are wrapped inward and extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20 . The ends  64 ,  66 , of the wing folds  50 ,  52 , may extend up to the sides of the side branch shaft  20  or they may extend up and over the side branch shaft  20 , such that the ends  64 ,  66 , are in immediate proximity, up to the point of touching each other or they may curl inward, as shown in  FIG. 7 . The third wing fold  62  is positioned at a 6-oclock orientation  68  from a cross-sectional view perspective and is wrapped in either a clockwise or a counter clockwise direction. Wing folds  50 ,  52 , may be as long as or longer than wing fold  62 .  
         [0050]     In the embodiment shown in  FIG. 8 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that two wing folds  70 ,  72 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  84 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  70 ,  72 , axially extend along the length of the balloon  14 . The wing folds  70 ,  72 , are folded such that they are wrapped inward and extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20 . The wing folds  70 ,  72 , extend up and over the side branch shaft  20 , to an extent such that the wing folds  70 ,  72 , overlap each other.  
         [0051]     In the embodiment shown in  FIG. 9 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that two wing folds  74 ,  76 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  84 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  74 ,  76 , axially extend along the length of the balloon  14 . The wing folds  74 ,  76 , are folded such that they are wrapped inward and extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20 . The wing folds  74 ,  76 , curl inward to the parent shaft  18  on either side  23 ,  25 , of the side branch shaft  20 .  
         [0052]     In the embodiment shown in  FIG. 10 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that three wing folds  78 ,  80 ,  82 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  21 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  78 ,  80 ,  82 , axially extend along the length of the balloon  14 . The wing folds  78 ,  80 , are folded such that they extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20  and are wrapped outward and down, overlapping the central body  84  of the balloon  14 . The third wing fold  82  is positioned at a 6-oclock orientation  68  from a cross-sectional view perspective and is wrapped in either a clockwise or a counter clockwise direction. Wing folds  50 ,  52 , may be as long as or longer than wing fold  62  or wing fold  62  may be longer than wing folds  50 ,  52 .  
         [0053]     In the embodiment shown in  FIG. 11 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that two wing folds  88 ,  90 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  21 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  88 ,  90 , axially extend along the length of the balloon  14 . The wing folds  88 ,  90 , are folded, such that they extend from the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20  and are wrapped outward and down, overlapping the central body  84  of the balloon  14 . The wing folds  88 ,  90 , curl inward on itself toward the parent shaft  18  on either side of the central body  84 .  
         [0054]     In the embodiment shown in  FIG. 12 , the balloon  14  and shafts  18  and  20  are positioned within contracted stent  26 . As mentioned above, the balloon  14  is positioned about the parent shaft  18  and the side branch shaft  20  is positioned outside of the balloon  14 , such that a portion of the balloon  14  is between the side branch shaft  20  and the parent shaft  18 . The side branch shaft  20  is outside of the inner space  15  of the balloon  14 . The balloon is folded, such that two wing folds  96 ,  98 , are created. Although the illustrations show space  19  within the wing folds, it should be understood that, when the balloon  14  is deflated, the wings may flatten and extend from a central body  21 , which is formed from the balloon material deflated around and close to the parent shaft  18 . The wing folds  96 ,  98 , axially extend along the length of the balloon  14 . The wing folds  92 ,  94 , are folded, such that they extend up from the sides of the parent shaft  18  toward and on either side  23 ,  25 , of the side branch shaft  20  and are wrapped outward and down, overlapping themselves. As with the other embodiments, the majority of the balloon  14  material is positioned on the sides  101 ,  103 , of the parent shaft  18 /side branch shaft  20  combination, increasing the minor axis  102  and decreasing the major axis  104 . The device thereby becomes more circular and more symmetrical, reducing the maximum profile. Increasing the balloon fold material on the sides increases the surface area that the stent  26  has to grip to, increasing stent securement.  
         [0055]     In  FIGS. 6, 9 ,  11 , and  12 , the balloon folds are symmetrical. As the balloon unwraps during deployment, the torque caused by the friction between the balloon folds and stent rotation are neutral due to cancellation of opposite forces. Due to the symmetry in the proposed fold designs, the balloon unfolds in a manor that preserves the radial location of the bifurcated stent just prior to deployment. The prevention of device rotation allows the aligning of the stent to the opposing side branch vessel.  
         [0056]     The symmetrical balloon folds eliminate any radial motion of the stent from pre-deployment to the stent being opposed to the vessel wall. The function of minimizing balloon material on the major axis and maximizing it on the minor axis is to reduce profile and gain more uniform stent securement. The symmetrical wing fold designs generate forces in opposite directions thus holding the radial position of the delivery system and stent. Having balloon material over the side branch lumen allows for higher stent securement and complete 360 degree cone puffing, as shown in  FIGS. 6 and 8 .  
         [0057]     The folds of the embodiments provide a more circular profile once the stent is crimped on and provide radial support for the side branch lumen. A more circular profile is more compatible with existing stent crimping and processing equipment. As shown in some figures, such as  FIGS. 6 and 8 , the design allows the stent to have complete contact with the balloon material, thus increasing stent securement performance. Also, having balloon folds over the side branch lumen enhances the edge protection performance.  
         [0058]     The present invention also contemplates a stent securement component coaxially mounting on the parent shaft  18  within the balloon  14 . Such securement components are described in U.S. Pat. No. 6,663,660, which is herein incorporated in its entirety.  
         [0059]     The catheter shafts may be constructed of any of a variety of suitable materials such as: PEBAX, nylon, urethane, and/or other materials in a single layer, multi-layer and/or braided configuration.  
         [0060]     Balloon  14  may be a typical angioplasty, stent delivery balloon or other inflatable member, which may be used or incorporated into a catheter assembly. The balloon  14  may be constructed of any suitable balloon material known to those of skill in the art. Commonly employed materials include the thermoplastic elastomeric and non-elastomeric polymers and the thermosets including the moisture curable polymers. Examples of suitable materials include but are not limited to, polyolefins, polyesters, polyurethanes, polyamides, polyimides, polycarbonates, polyphenylene sulfides, polyphenylene oxides, polyethers, silicones, polycarbonates, styrenic polymers, polytetraflouroethylene, copolymers thereof, and mixtures thereof. Some of these classes are available both as thermosets and as thermoplastic polymers.  
         [0061]     In some embodiments the stent or other portion of the assembly may include one or more areas, bands, coatings, members, etc. that is (are) detectable by imaging modalities such as X-Ray, MRI or ultrasound. In some embodiments at least a portion of the stent, sheath and/or adjacent assembly is at least partially radiopaque.  
         [0062]     Catheter systems for delivery of multiple stents or stent segments are described in U.S. patent application Ser. No. 10/375,689, filed Feb. 27, 2003 and U.S. patent application Ser. No. 10/657,472, filed Sep. 8, 2003 both of which are entitled Rotating Balloon Expandable Sheath Bifurcation Delivery; U.S. patent application Ser. No. 10/747,546, filed Dec. 29, 2003 and entitled Rotating Balloon Expandable Sheath Bifurcation Delivery System; U.S. patent application Ser. No. 10/757,646, filed Jan. 13, 2004 and entitled Bifurcated Stent Delivery System; and U.S. patent application Ser. No. 10/784,337, filed Feb. 23, 2004 and entitled Apparatus and Method for Crimping a Stent Assembly; the entire content of each being incorporated herein by reference.  
         [0063]     As used herein the term ‘stent’ refers to an expandable prosthesis for implantation into a body lumen or vessel and includes devices such as stents, grafts, stent-grafts, vena cava filters, etc. In some embodiments a stent may be at least partially constructed of any of a variety of materials such as stainless steel, nickel, titanium, nitinol, platinum, gold, chrome, cobalt, as well as any other metals and their combinations or alloys. A stent may be at least partially constructed of a polymer material. A stent may be at least partially constructed of a shape-memory polymer or material. A stent may be balloon expandable, self-expandable, hybrid expandable or a combination thereof. In some embodiments a stent or some other portion of the catheter may include one or more areas, bands, coatings, members etc that is (are) detectable by imaging modalities such as X-Ray, MRI or ultrasound. In some embodiments at least a portion of the stent is at least partially radiopaque. In some embodiments a stent may include one or more therapeutic and/or lubricious coatings applied thereto.  
         [0064]     Embodiments of the present invention can be incorporated into those shown and described in the various references cited above. Likewise, embodiments of the inventions shown and described therein can be incorporated herein.  
         [0065]     In the various embodiments described herein, the catheter assembly  10  may be a fixed wire catheter or any other catheter design.  
         [0066]     The above materials throughout the application are intended for illustrative purposes only, and not as a limitation on the scope of the present invention. Suitable polymeric materials available for use are vast and are too numerous to be listed herein and are known to those of ordinary skill in the art.  
         [0067]     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.  
         [0068]     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.  
         [0069]     With this description, those skilled in the art may recognize other equivalents to the specific embodiment described herein. Such equivalents are intended to be encompassed by the claims attached hereto.