Abstract:
A catheter assembly and method of use comprises advancing a catheter having a rotatably mounted balloon relative to the primary guide wire to a vessel bifurcation along first and second guide wires.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from U.S. provisional application 60/314,467, filed Aug. 23, 2001 the entire contents of which are incorporated herein by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   At least one embodiment of the present invention is directed to the field of stents and stent delivery systems used to treat stenoses, and more particularly to stenoses at a bifurcation of a passage. 
   2. Description of the Related Art 
   Stent systems are widely used in the treatment of stenoses. Intravascular stents are used in coronary, renal, and carotid arteries, for example, to maintain an open passage through the artery. In patients whose coronary heart disease consists of focal lesions, stents have proven effective. For example, where only a single coronary artery is clogged or where there are short blockages in more than a single artery, stents have been used with a great amount of success. An intravascular stent may be positioned in a clogged artery by a catheter and is often set in place by inflating a balloon upon which the stent is mounted. This expands the diameter of the stent and opens the previously clogged artery. The balloon is then deflated and removed from the patient while the stent retains an open passage through the artery. 
   It is recognized, however, that a stent can be deployed in manners other than inflating and deflating a balloon. For example, self-expanding stents have been developed in which a cover is removed from over a stent, thereby allowing the stent to deploy or spring into place. It is also contemplated that other deployment mechanisms or means may be used or developed to advantageously deliver and deploy a stent in position. 
   Nevertheless, a need still exists for properly delivering and locating a stent at a bifurcation. Although efforts have been made to use a stent at bifurcations, these sites have previously been inadequately treated by a stent. For example, U.S. Pat. No. 5,749,825 is representative of a catheter system that treats stenoses at an arterial bifurcation. The disclosure of U.S. Pat. No. 5,749,825 is hereby incorporated by reference. 
   A stent having different diameters has been proposed to allow placement in both a main passage, such as an artery, and a side branch passage, such as a continuation branch artery. Additionally, these stents generally have a circular opening which allows for unimpeded blood flow into the side branch artery. However, problems are still encountered in orienting the stent relative to the side branch at the bifurcation of the main and branch passages. 
   Many current devices rely on either passive torque (e.g., pushing the stent forward and allowing the stent that is fixed on the guide wire/balloon to passively rotate itself into place) or creating torque from outside of the patient to properly orient the stent delivery system in the passage. These devices and methods of achieving proper angular orientation have not been shown to be effective in properly placing and positioning the stent. As will be appreciated and understood by those skilled in the art, improper placement of the stent with respect to its rotational or circumferential orientation, or its longitudinal placement, could lead to obstruction of the side branch passage. It is important to properly position or center an opening formed in the bifurcated stent with the side branch passage to maximize flow therethrough. 
   Thus, a need exists for effectively treating stenosed passage bifurcations. This need includes more precise and exact longitudinal placement and rotational/circumferential orientation of the stent. 
   Commercially available devices do not maintain side branch access at the time of stent deployment. This results in the potential for plaque shift and occlusion of the side branch passage. 
   It would also be advantageous if stents could be placed across the side branch while wire position is maintained thereby helping to protect and secure further access to the side branch. 
   All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
   Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
   A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims. 
   BRIEF SUMMARY OF THE INVENTION 
   Some embodiments of the present invention include a freely rotating deployment system for a stent assembly maintaining side branch access and protection. 
   The present invention contemplates a new and improved apparatus and method that improves the orientation of a stent by providing a more exact placement of the stent relative to the side branch passage. This, in turn, leads to better protection of the side branch passage. The present invention has the potential for improvement in trackability of the stent delivery system. 
   At least one embodiment of the invention includes a freely rotatable catheter balloon surrounding a main hollow member or hypotube. The stent surrounds both the catheter balloon and the main hypotube. A side branch hollow member or side branch hypotube is attached to the catheter balloon and lies underneath the stent. A distal end of the side branch hypotube exits the stent at a desired longitudinal position while a proximal end of the side branch hypotube extends beyond the proximal end of the stent. At the distal exit point, the stent includes an opening that, after deployment of the stent, allows for blood flow through the ostium of the side branch artery. 
   The balloon is connected to the stent delivery system. In some embodiments, the balloon is attached both distally and proximally to rotate freely about the main hypotube. The rotating members rotate about the main hypotube and are limited longitudinally by first and second fixed members non-rotatably secured to the main hypotube. The balloon stent assembly rotates freely about the axis defined by the main hypotube and any radial movement is limited by the main hypotube. This construction allows the side branch guide wire to direct the stent assembly to rotate freely and passively to the proper circumferential orientation. Upon inflating the balloon, the fixed and rotated members secure the circumferential orientation of the stent delivery system. Thus, the side branch guide wire properly orients the stent delivery system in its correct position relative to the side branch. 
   A primary feature of some embodiments is that at the time of positioning the stent, the stent will be properly oriented relative to the side branch, i.e., a stent delivery system and method that correctly positions the stent in a bifurcated passage. 
   Another advantageous feature is side branch protection with the guide wire during stent deployment. 
   Another benefit of this invention resides in proper alignment of the stent delivery system in a bifurcated passage to achieve correct circumferential orientation relative to a side branch passage, and securing the desired orientation. 
   Yet another benefit of this invention is the ability to properly place the stent delivery system longitudinally relative to the side branch. 
   A further advantage of the system is that tangled wires pose less of a problem. 
   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) 
     A detailed description of the invention is hereafter described with specific reference being made to the drawings. 
       FIG. 1  is a cross-sectional side view of a rotating stent delivery catheter assembly for stenting an arterial bifurcation in its pre-deployment configuration, with the catheter balloon shown inflated. 
       FIG. 2  is a perspective view of the stent delivery assembly of  FIG. 1  shown with a stent disposed about the balloon. 
       FIG. 3  is a perspective view of the stent delivery catheter assembly of  FIG. 1  as it would appear in the collapsed state prior to having a stent mounted on the balloon. 
       FIG. 4  is a perspective view of a stent delivery system with the balloon in an inflated state and the side branch hypotube in an open condition. 
       FIG. 5  is an enlarged view of the distal exit point of the side branch hypotube and the opening of the rotating stent delivery catheter assembly of  FIG. 2 . 
       FIG. 6  is a perspective view of a proximal shaft of an alternate stent delivery catheter assembly having only one rotating joint that is self sealing when pressure is applied or withdrawn. 
       FIG. 7  is an enlarged side view of a distal end of the rotating balloon assembly associated with  FIG. 6 . 
       FIG. 8  is an enlarged side view of the combined components of  FIGS. 6 and 7 , specifically portions of the distal end of the proximal fixed shaft in  FIG. 6  combined with the proximal end of the freely rotatable distal portion in  FIG. 7  creating a rotating stent delivery catheter assembly with a single rotating joint that is self sealing. 
       FIG. 9  is an enlarged side elevational view of  FIGS. 6 and 7  showing the combined of components of  FIGS. 6-8  in their entirety. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   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. 
   For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated. 
   Referring now to the drawings wherein the showings are for the purposes of illustrating the preferred embodiments of the invention only and not for purposes of limiting same,  FIG. 1  shows a stent delivery system or assembly  10 . Assembly  10  includes a first guide member, or main guide wire  12  that extends axially through a first hollow or tubular member  14 . The first hollow member  14  will also be identified as a main hypotube, although it will be appreciated that the particular shape or configuration of this component may change from that illustrated in the drawings. The main guide wire  12  is used as the delivery guide of the stent catheter assembly  10  to a stenosed region of a passage such as an artery (not shown). The main hypotube  14  is preferably a hollow cylinder with openings on both its distal and proximal ends, respectively end  16  and end  18 , which allows for passage of the main guide wire  12  therethrough. A first fixed member, or distal fixed body  20  and a second fixed member, or proximal fixed body  22  are non-rotatably secured to distal end  16  and proximal end  18  of the main hypotube  14 . Although described as separate elements, it will be understood that the fixed bodies  20  and  22  and the main hypotube  14  can be separate components that are secured together or an integrally formed assembly if desired for ease of manufacture or assembly. The fixed bodies  20  and  22  are preferably tapered from smaller diameter, axially outer ends to larger diameter, intermediate ends for reasons that will become more apparent below. 
   A first rotating member or distal rotating member  24  and a second rotating member or proximal rotating member  26  are axially spaced apart and located between the distal fixed body  20  and proximal fixed body  22 . The rotating members  24  and  26  are preferably of the same general diameter throughout their length and rotate freely about the axis of the main hypotube  14 . 
   Sealed to the proximal and distal rotating members  24  and  26  are opposite ends of a catheter balloon  28 . A distal end  30  of the catheter balloon is sealingly joined to (or integrally formed with) the distal rotating member  24  while a proximal end  32  of the catheter balloon is sealingly joined to (or integrally formed with) the proximal rotating member  26 . Thus, the balloon is free to rotate relative to the main hypotube, a feature that provides advantages and benefits over known stent assemblies. It is also contemplated that the rotating members  24  and  26  can be formed of sealing or elastomeric material (or incorporate a separate seal member) so that slight axial movement of the balloon  28  and of the rotating members  24  and  26  engages and seals against the fixed bodies  20  and  22  upon inflation of the balloon  28 . The balloon  28  and the rotating members  24  and  26  can hold high pressure and seal at the ends. It will be appreciated that the rotating members  24  and  26  are preferably constructed to maintain a cylindrical configuration under pressure so that the balloon  28  is free to rotate relative to the main hypotube  14  when pressurized. 
   In some embodiments the stent delivery catheter system further includes an outer hollow/tubular member or outer hypotube  40  received over the main hypotube  14 . The outer hypotube  40  is radially spaced from the main hypotube  14  at a first or proximal end  42  to define an annular space  43  through which fluid from an external source (not shown) is introduced to inflate the balloon. In at least one embodiment, a second or distal end  44  of the outer hypotube  40  is sealed to the main hypotube  14  so that fluid cannot escape therefrom. Alternatively, the distal end of the outer hypotube extends only partially into the balloon  28 . In addition, one or more openings, or contrast ports,  46  are provided in the outer hypotube  40  at a location within the balloon  28  so that the fluid can enter the cavity defined between the balloon  28  and the outer hypotube  40  as illustrated by the directional arrows in  FIG. 1 . Alternatively, the opening  46  may define the distal end of the outer hypotube  40 . In at least one embodiment, the balloon  28  is fully inflated at the proximal end  42  and then begins to inflate at the distal end  44 . The outer hypotube  40  may be advantageously and integrally formed with the first and second fixed members  20  and  22  for ease of manufacture, although it will be appreciated that these may be separate members without departing from the scope and intent of the invention. 
   A conventional or specially designed medical device, such as a stent  50 , encloses a portion of the catheter balloon  28 , such as is shown in  FIG. 2 . The stent  50  is typically a metal sleeve of mesh construction that is advanced into the stenosis riding on the balloon  28  of the catheter assembly  10 . Once properly positioned, the balloon  28  is inflated with an inflation fluid, such as saline and contrast, through the passage  43  between the main hypotube  14  and the outer hypotube  40 , which expands the balloon  28  and expands or radially opens the stent  50  to compress an atheroma that is narrowing the passage wall. Although the balloon  28  is subsequently deflated for removal from the patient with the catheter assembly  10 , the stent  50  remains in its expanded state allowing increased flow through the previously closed/blocked (stenosed or narrowed) region. Alternatively, a self-expanding stent not requiring a balloon for delivery or deployment can be used without departing from the scope and intent of the present invention. 
   A second or branch tubular member  60 , also referred to as a side branch hypotube, is provided between the catheter balloon  28  and the stent  50 . As evident in  FIG. 2 , the side branch hypotube  60  carries or receives a side branch guide wire  62 . The side branch hypotube  60  extends from the proximal end of the stent  50  between the stent and balloon and exits the stent at an intermediate longitudinal position through an opening  64 . The opening  64  provides for both the exit of the side branch hypotube  60 , as well as the unobstructed passage of blood flow into the side branch passage once the stent has been deployed. It should be understood, however, that the side branch hypotube opening  64  could be placed at any convenient position along the stent. 
   An enlarged view of the side branch hypotube opening  64  in the stent  50  is shown in  FIG. 5 . The side branch hypotube  60  exits from underneath the proximal end of the stent. Upon deployment of the stent  50 , the side branch hypotube opening  64  allows for unobstructed blood flow to the ostium of the side branch passage. As will also be appreciated, the side branch hypotube  60  is fixed or secured to the exterior of the balloon. Thus, the side branch hypotube  60 , balloon  28 , and rotating members freely rotate as a unit relative to the main hypotube  14  for accurate, passive positioning with the side guide wire and thus accurate positioning of the stent  50  relative to a saddle point of the bifurcated passage. With continued reference to  FIG. 2 , the catheter balloon  28  is inflated, the stent  50  is deployed, and the rotating members  24  and  26  are interlocked with the fixed members  20  and  22  to stop the rotating action of the stent delivery system and create a pressure tight system. 
   The side branch hypotube  60  may also be slit  66  along its longitudinal length to facilitate removal of the side guide wire  62  as is shown in  FIGS. 3 and 4 . The side branch hypotube  60  is secured to the balloon  28  along its length at a circumferential location opposite the longitudinal slit, i.e., diametrically opposite the slit  66 . The natural elasticity of the side branch hypotube  60  is utilized so that when the balloon  28  is inflated, such as is shown, the side branch hypotube  60  is substantially cylindrical in shape to enclose the portion of the side guide wire  62  therein such as is shown in  FIG. 2 . When the balloon is inflated, it exerts a tensile force on the side branch hypotube  60  that opens the hypotube  60  along its length, such as in the manner shown in  FIG. 4 . As a result the side guide wire  62  is released through the slit  66 . When the balloon  28  is deflated, such as is shown in  FIG. 3 , the side branch hypotube  60  again adopts a cylindrical conformation whereby the remainder of the stent delivery system (balloon and catheter) can be easily removed. 
   The split side branch hypotube  60  offers another desirable feature. The split hypotube  60  allows for immediate placement of a second balloon into the side branch for simultaneous “kissing” balloon inflation. In other words, first and second balloons are simultaneously located in the main and side branch passages such that their proximal ends abut and their distal ends are placed in each respective branch. This is to be contrasted with use of an unsplit or solid side branch hypotube which would require removal of the first balloon prior to insertion of a balloon in the side branch. 
   An alternative rotating stent delivery system is illustrated in  FIGS. 6-9 . For purposes of brevity, like components will be referenced by like numerals with a primed suffix (′) and new elements will be identified by new numerals. 
   A proximal shaft is generally well known in the art and may take numerous forms; however, the proximal shaft  70  shown in  FIGS. 6-9  preferably includes a bushing  72  at a distal end and a seal  74  comprised of a soft material. The seal  74  is connected to the proximal shaft  70  and, as shown, tapers to a smaller diameter and envelops the main hypotube  14 ′, as is shown in  FIGS. 8 and 9 . Within lumen  76  of the proximal shaft  70 , the bushing  72  abuts against an interior distal end of the proximal shaft. 
   With reference now to  FIG. 7 , a distal rotating portion of proximal shaft  70  is shown. A separate hypotube  14 ′ includes a proximal end with a first bushing  80  and a second bushing  82  axially spaced therefrom along the separate hypotube  14 ′. A second seal  84  comprised of a soft material, is connected to the first bushing  80  at the proximal end of the separate hypotube  14 ′. The annular second seal  84  protrudes substantially parallel along the longitudinal axis of the main hypotube and extends axially beyond an opening  86  for the main branch guide wire (not shown). Additionally, a third annular seal  88  is shown connected to the first bushing  80 . The third seal  88  has a smaller diameter and lies axially and radially inward of the second seal  84 . The third seal  88  is also secured to the first bushing  80  of the separate hypotube  14 ′ and tapers radially inward as it extends longitudinally in a direction away from the separate hypotube  14 ′, to envelope the main guide wire  12 ′. 
   The integration of the proximal end of the separate hypotube  14 ′ and the distal end of the proximal shaft  70  is shown in  FIG. 8 . Particularly, the first and second bushings  80 ,  82  of the hypotube  14 ′ are of a diameter that allows them to fit under or within the particular components of the proximal shaft  70 . Specifically, the second bushing  82  of the hypotube  14 ′ is distal to the proximal shaft bushing  72  and is enveloped by the first soft seal  74  of the proximal shaft  70 . The first bushing  80  of the hypotube  14 ′ is adjacent to the bushing  72  of the proximal shaft and is enveloped by the proximal shaft  70 . 
   With continued reference to  FIG. 8 , the integrated hypotube  14 ′ and proximal shaft  70  are shown in a freely rotatable position. In this mode, the hypotube  14 ′ rotates freely while the proximal shaft  70  remains fixed. Positive pressure allows the seals  82  and  88  extending from the first bushing  80  of the hypotube  14 ′, to contact the proximal fixed shaft  70  and main guide wire  12 ′ hence sealing the balloon delivery system  10 ′ allowing for all positive pressure to be transferred to the balloon  28 ′. This provides for expansion of the balloon  28 ′ and deployment of a stent such as previously described. Alternatively, as is shown in  FIG. 9  negative pressure applied within the shaft  70  will create contact between the separate hypotube and the seal  74  of the proximal shaft  70 . Also, contact will be created at the distal end of the separate hypotube between the soft material and the wire  12 ′ creating a seal there as well. These seals allow for all negative pressure to be transmitted to the balloon allowing for collapse and then removal of the balloon. 
   Thus, it is apparent that a truly unique feature of the invention is a freely rotating stent assembly that provides a more exact placement of the stent relative to the side branch passage. 
   The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. For example, the illustrated embodiments use a balloon to expand the stent although, as briefly noted above, a self expanding or self deploying stent can be used without departing from the features of the present invention. Likewise, using a fixed wire on the distal end of the apparatus is also recognized as being consistent with the features of the present invention. Moreover, the preferred embodiments describe a side branch hypotube, either split or unsplit, that is associated with the side branch guide wire. It will be further appreciated that the side branch guide wire could be carried and/or released in a variety of other ways. The invention is intended to include all such modifications and alterations thereof. 
   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. 
   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. 
   This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.