Abstract:
The present disclosure concerns a delivery system for delivering a medically useful payload through the vasculature to a site of interest in the patient&#39;s body. The medically useful payload may be a therapeutic device, such as a stent, and it may be a diagnostic tool, such as an imaging device. Owing to its structural attributes, the presently-inventive delivery system is well suited for carrying medical payload to and through vessel curvature and to branched regions (i.e., bifurcations) in same. Also, the device is well-suited to traveling through a vessel over a guiding element, such as a guidewire, which itself exhibits curvature.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is related to U.S. provisional patent application No. 60/757,123, filed Jan. 6, 2006, now pending. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present disclosure concerns a delivery system for delivering a medically useful payload through a channel in the patient&#39;s body, such as the vasculature, to a site of interest. The medically useful payload may be a therapeutic device, such as a stent, and it may be a diagnostic tool, such as a camera. Owing to its structural attributes, the presently-inventive delivery system is well suited for carrying medical payloads to and through vessel curvature and to branched regions (i.e., bifurcations) in same. Also, the device is well-suited to traveling through a vessel over a guiding element, such as a guidewire, which itself exhibits curvature. 
       BACKGROUND OF THE INVENTION  
       [0003]    Diseases of the vasculature, such as stenoses, strictures or aneurysms in blood vessels and other body vessels can be treated by the implanting a payload, such as a stent, graft, or the like, at the site of disease. Such payload can be carried to the site of implantation by a delivery device having a catheter for carrying and deploying the payload. The catheters can be expected to carry the payload over a relatively long distance, often from an incision in the patient&#39;s groin area, through the vasculature, to a location where action is required. For example, a site in the vicinity of the patient&#39;s heart may be the target for payload deployment. 
         [0004]    From incision to deployment site, the path is defined by the interior of a vessel that the catheter must travel. The vessel may have segments that are difficult to traverse. Curves or bifurcations in vessels exemplify two particular kinds of segments that can present such difficulties. Likewise, the deployment site may be curved, or a bifurcation may be present at the site of deployment. 
         [0005]    A bifurcation in a vessel is a location where the vessel divides into two branches or parts. The vessel bifurcations generally have circumferential asymmetry. That is, bifurcated vessels generally exhibit asymmetry around their circumference at the point where the main vessel divides into one or more branches. Thus, the opening in the side branch vessel where the side branch vessel joins the main branch vessel may be asymmetrical. The side branch vessel may join the main branch vessel at an oblique angle, which may contribute to the asymmetry of the bifurcation cross-section. 
         [0006]    One kind of prior art bifurcation delivery device employs multiple guidewires and/or the clinician to orient and manipulate the device relative to the bifurcation. For example, attempts have been made to accomplish this solely through the use of two wires or wire-like elements (one in each branch of bifurcation) to force rotation of the device to match the vessel anatomy. This approach has shortcomings. First, by requiring delivery of the medical device to the location of the bifurcation over two wires (for substantially the entire delivery), the chance of wire wrapping is greatly increased. This prevents complete delivery of the device and can result in the clinician having to withdraw a wire and rewire the vessels, causing significant procedural delay and patient risk. Second, reliance on two wires for device orientation is typically insufficient to guarantee full and proper alignment of the entire medical device with the side branch ostium (particularly the portion of the device proximal to the carina (or apex) of the bifurcation) Even when both branches of the bifurcation are wired and the medical device is seated on the carina, the wires are not able to exert enough rotational influence on the device to align the whole length of the payload. 
         [0007]    In any event, carrying the payload through a vessel curvature, a bifurcation, or otherwise deploying the payload at such locations can present challenges in terms of traversing or accessing the site. Furthermore, where the payload needs to be in a specific orientation (such as for maximizing the therapeutic effect or diagnostic purpose of the payload), achieving the desired orientation in such curvature or bifurcation presents yet another challenge to the person of skill in the art. 
         [0008]    U.S. Pat. No. 6,544,218, entitled “Catheter With Biased Shaft” is disclosed as a reference of interest. 
       SUMMARY OF THE INVENTION  
       [0009]    The present invention is directed to a flexible catheter for the delivery of a medically useful payload to a target site within a patient&#39;s body. By way of example, the medically useful payload may be a stent, or it could be an atherectomy member. In these instances, the medically useful payload is delivered to a site of disease within a blood vessel of a patient. In yet other examples the medically useful payload may be a camera, a light, or both, which can be carried to a site where observation is warranted for purposes of making a medical diagnosis. In one aspect of the present invention, a flexible region is located at a distal end of the delivery device, which flexible region exhibits a preferential bending direction. That is, the structure of the flexible region permits bending in substantially only one direction. The flexible distal region can curve or bend in a preferred direction that permits the device to bend in accordance with the shape of the vessel or guidewire (if possessing a curved segment) on which the delivery device may be tracked. 
         [0010]    Thus, the delivery device of the present invention is adapted to deliver medical payloads(such as stents) to vessels that are curved and/or bifurcated, or other vessel configurations, such as those with eccentric lesions, that are better serviced by deploying oriented devices. That is, there are occasions where the device should be oriented in a specific fashion relative to the bifurcation, curvature, or other vessel feature, or even oriented in response to a bend in the guidewire. Such orientation can be achieved with the present invention. 
         [0011]    In another aspect of the present invention, the unidirectional bending member with preferred bending direction is distally located on the delivery device and is coupled thereto to allow a degree of torsional movement of the unidirectional bending member, relative to other parts of the device. That is, the unidirectional bending member is attached to the delivery device in a manner that allows the unidirectional bending member to rotate as necessary to orient the member and conform the distal end of the device, where the member is located, to the shape of the vasculature, in order to deploy or carry the payload so the payload can be properly oriented. 
         [0012]    In a further aspect of the present invention, the payload can be co-located with the unidirectional bending member. For example, a stent can be positioned in or over the unidirectional bending member. In an alternative arrangement, the payload is not co-located with the unidirectional bending member, yet is coupled to the unidirectional bending member through sufficient intervening structure so as to undergo orientation in response to the orientation of the unidirectional bending member. 
         [0013]    In a specific aspect of the present invention, the unidirectional bending member, owing to its structural attributes and/or construction, can bend in substantially only one direction. A structural arrangement of this kind can result from providing only one member segment or side that the member can bend around. This particular member segment or side becomes the interior, or short side, of the bend. 
         [0014]    In a more specific aspect of the present invention, another bending member side, most likely positioned opposite from the bending member side which the member is capable of bending around may be provided with a structural attribute that allows that member segment to function as the outer side which the member bends around. This particular member segment or side becomes the exterior, or long side, of the bend. 
         [0015]    A member cut into a plurality of segments, wherein the adjacent segments on one side of the member are connected to each other, and wherein the segments are not interconnected on the side opposite the connections, exhibits bending in substantially only one direction. The interconnected side would be the interior, or short side of the bend (with the member bending around the interconnections) and the open side would be on the exterior, or long side, of the bend. 
         [0016]    In the aforedescribed arrangement, the member can bend substantially in only one direction, that is, around the interconnections. The interconnections are sufficiently stiff so as to prevent the member from bending in a manner in which the interconnections are positioned on the long side of the bend. Thus, the member can bend in substantially only one direction. It should be understood that the universal bending member of the present invention could be solid, and it also may be tubular. Tubular arrangements may be easier to fabricate, and further, can move along or otherwise be positioned over a guiding element, such as a guidewire. Thus, in certain arrangements, tubular unidirectional bending members may be preferred. 
         [0017]    The substantially unidirectional bending characteristic of the unidirectional bending member of the present invention facilitates orientation of the device as it travels through (1) curves or bifurcations in the vessel, (2) curves or bends in the guidewire, or (3) other eccentricities located within the vessel that force the member into a curved path. So long as the unidirectional bending member possesses a sufficient degree of freedom to rotate, it will assume the path of least resistance in the course of its travels, and thereby rotate/orient itself to conform to the bend in the vessel. Thus, by linking or associating a payload with the unidirectional bending member, orientation of the payload can be attained as a result of the orienting action undertaken by the unidirectional bending member. 
         [0018]    Aside from being adapted to pass relatively easily through bends and curves in the vasculature, the self-orienting unidirectional bending member can be used in a number of beneficial ways. Stents deployed at the site of or in the vicinity of a bifurcation may have asymmetrical design features intended to conform to the bifurcation, and in particular, the side branch ostium. Such stents must be deployed in the proper orientation, a result that can be obtained by coupling such stents to the unidirectional bending member, and then allowing the member to orient itself in the vessel. Likewise, a camera or other diagnostic tool, such as an ultrasound transducer (IVUS), pressure transducer, infrared sensor, endoscope lens coupled to the unidirectional bending member could be properly oriented as a result of unidirectional bending member orientation. Furthermore, the self-orienting nature is useful where the bend, so to speak, is imparted by the guidewire which passes through the catheter. For instance, the unidirectional bending member may travel over a guide wire passed into a bifurcation side branch, allowing a stent to be deployed, in its proper orientation, in the side branch. In yet another example, a guidewire having a prebent section can be used to effect orientation of the unidirectional bending member in situations where vessel characteristics are not of an orientation-producing nature. In other words, by positioning the bend in the guidewire at the desired location, the unidirectional bending member will orient itself as it traverses the bend. This arrangement is advantageous where it is desirable to achieve orientation in a relatively straight vessel segment. In any event, with these arrangements, rotation of the unidirectional bending member for positioning of payload, whether for deployment or other medically useful purpose is facilitated. Further, it should be understood that with the unidirectional bending member of the present invention, it is not just the payload which is properly oriented. For example, in the case of a bifurcated vessel, the side branch guidewire exit port can be oriented to face the ostium of the side branch vessel. In other words, as the unidirectional bending member rotates, the side branch guidewire exit port aligns according to the unidirectional bending member orientation, with the side branch guidewire element facing the side branch ostium. This arrangement makes it possible for the unidirectional bending member to properly orient to the side branch anatomy when the device is seated at the carina of the bifurcation. This arrangement also makes it easier for the side branch guide wire to be advanced out of the delivery catheter and into the side branch. 
         [0019]    The flexible portion of the delivery device can be constructed a number of other ways. For example, the directional mechanical properties of a material can be manipulated in order to increase flexibility in desired locations about the circumference of the unidirectional bending member. As an alternative, the material properties can be distributed around the circumferential direction of the delivery device, thereby creating a preferred bending direction. The geometry of a structure can also be altered in order to create flexibility in the preferential direction of the bend. As will be explained in the detailed description of the invention, there are a number of ways to attain a preferred bending direction, and in particular, a unidirectional bending direction, in a delivery device component. 
         [0020]    Chemical, electrical/thermal or mechanical means can be used to modify unidirectional bending member stiffness so the unidirectional bending member can be transversely displaced, resulting in a preferred bending orientation. For example, the unidirectional bending member may be provided with a substantially unidirectional bend by the manual placement or displacement of a stiffening material within the unidirectional bending member. The unidirectional bend may be effected by thermally modifying at least one portion of the unidirectional bending member. The unidirectional bend may be effected by chemically modifying at least one portion of the unidirectional bending member. The unidirectional bend may be effected by electrically inducing a variation in material phase change, change in modulus, or change in yield stress in the unidirectional bending member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a perspective view of a device of the present invention. 
           [0022]      FIG. 2  is a cross sectional view of an aspect of the present invention. 
           [0023]      FIG. 3  is a cross sectional view of another aspect of the present invention. 
           [0024]      FIG. 4  is a cross sectional view of another aspect of the present invention. 
           [0025]      FIG. 4A  is a cross sectional view of another aspect of the present invention. 
           [0026]      FIG. 4B  is a cross sectional view of another aspect of the present invention. 
           [0027]      FIG. 5  is a perspective view of an embodiment of a unidirectional bending member of the present invention; 
           [0028]      FIG. 5A  is a top plan view of the unidirectional bending member shown in  FIG. 5 ; 
           [0029]      FIG. 5B  is a cross sectional view taken along line D-D in  FIG. 5A ; 
           [0030]      FIG. 5C  is a cross sectional view taken along line H-H in  FIG. 5A ; 
           [0031]      FIG. 6  is a detailed view of the embodiment shown in  FIG. 5 ; 
           [0032]      FIG. 7  is a perspective view of the embodiment shown in  FIG. 5 , shown while flexing; 
           [0033]      FIG. 8  is a top plan view of the embodiment shown in  FIG. 5 , shown while flexing; 
           [0034]      FIG. 9  is a detailed view of the embodiment shown in  FIG. 5 , shown while flexing; 
           [0035]      FIG. 10  is a side view of the embodiment shown in  FIG. 5 , shown while flexing; 
           [0036]      FIG. 11  is a perspective view of an alternative embodiment of a unidirectional bending member of the present invention; 
           [0037]      FIG. 12  is a cross-sectional view of an alternative embodiment of a unidirectional bending member of the present invention; 
           [0038]      FIG. 13  is a cross-sectional view of yet another alternative embodiment of a unidirectional bending member of the present invention; 
           [0039]      FIGS. 14A-14F  are cross-sectional views of additional embodiments of a unidirectional bending member of the present invention; 
           [0040]      FIG. 15  is a cross-sectional view of an alternative embodiment of a unidirectional bending member of the present invention; 
           [0041]      FIG. 16  is a cross sectional view of a first bifurcation configuration in a patient&#39;s vasculature; and 
           [0042]      FIG. 17  is a cross sectional view of a second bifurcation configuration in a patient&#39;s vasculature. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0043]      FIGS. 1 and 2  illustrate a catheter  10  of the kind suitable for treating bifurcations in which the payload is a balloon expandable stent. Catheter  10  includes an inflatable balloon and therefore is useful for deploying a balloon expandable stent, although it should be understood that the delivery system described herein could be employed with a self expanding stent, obviating the need for an inflation balloon and lumen to transport inflation fluid(it should be noted that if the payload were an self expanding stent, such as one manufactured of the nitinol material, then the device would require a outer restraining sheath positioned over the stent). Catheter  10  generally comprises an elongated catheter shaft  11  having a proximal end  12 , a distal end  13 , At least one guidewire lumen  14  is adapted to receive and pass a guidewire, though a second guidewire lumen  18  is depicted here. An inflation port  20  at the proximal end of catheter shaft  11  has an opening for receiving an inflation fluid from an external source. The inflation port is in fluid communication with the open annular space  16  present within shaft  11 . Guidewire entry port  25  is found at the proximal device end, and can be in communication with guidewire lumen  14  or  18  that are discussed below. An RX guidewire lumen port  19  is located between proximal and distal ends  12  and  13  as shown in  FIG. 1 . RX guidewire lumen port  19  is in communication with the other of the guidewire lumens  14  or  18 . 
         [0044]    In the embodiment of  FIG. 1 , the shaft  11  is a multiple-lumen shaft, typically extruded or otherwise formed with at least one guidewire lumen  14 , and possibly second guidewire lumen  18  present in annular space  16 . Annular space is sealed on its exterior by wall of shaft  11  and therefore serves as the conduit for transferring the balloon inflation fluid. Here, where the device is intended for the delivery of a stent, at the site of a bifurcation, it is advantageous, though not entirely necessary, to employ a catheter that can receive and pass at least two guidewires  32  and  33 . The catheter shaft is provided with lumens for main branch and side branch guidewires, such lumens designated  14  and  18 , respectively. 
         [0045]    The distal end of the annular space  16  is proximal to the distal end of the guidewire lumens  14  and  18 . An inflatable balloon  17  is disposed on a distal section of catheter shaft  11 , having a proximal end and a distal end is secured and sealed to the shaft  11 . The opening in the balloon at its proximal end is in fluid communication with annular space  16  so that the balloon can receive and retain the inflation fluid as it flows from the external source, through inflation port  20 , through annular space  16 , and into balloon  17 . A stent  30  is mounted over the balloon  17 . See  FIG. 3 . Also shown there is side branch guidewire  32 , indicating that the payload tracks the side branch guidewire and thus payload deployment is to take place adjacent to a side branch ostium of a bifurcated vessel. By no means is this depiction intended to restrict the scope of the present application in any way, as the payload could have been depicted as tracking the main branch guidewire, i.e.,—intended for deployment in the main branch of the bifurcation. 
         [0046]    A unidirectional bending member  50  is located at the distal end of the catheter  10 . Unidirectional bending member  50  is mounted at the distal end of shaft  11 . In a specific arrangement, the proximal end of shaft  11  is constructed of a material that exhibits sufficiently high torsional flexibility so that the unidirectional bending member portion of the catheter is able to undergo the rotation necessary to orient the device. Employing an elastomeric material to construct the shaft in the area proximal to the unidirectional bending member  50  is one way to attain this result. In other arrangements, dimensions of shaft  11  can be varied in order to impart torsional flexibility in the region where the unidirectional bending element joins to the catheter. For example, the wall thickness of shaft  11  can be reduced in the area proximal to where the shaft  11  joins to the unidirectional bending member  50 , or alternatively, the diameter of the shaft  11  in this region can be reduced. In yet another arrangement, the unidirectional bending member is butt welded to the end of one of the guidewire lumens  14  or  18 . 
         [0047]    Exit ports  27  and  29  for main branch and side branch guide wires are located at approximately the mid-portion of the distal payload for the side branch guidewire (not shown) and the catheter tip ( 35 ) for the main branch guidewire. 
         [0048]    As shown in  FIG. 4 , the unidirectional bending member  50  is coaxially arranged with the main branch guide wire  33 , that is, with the guidewire arranged coaxially within unidirectional bending member  50 . Unidirectional bending member  50  extends within balloon  17  and is co-located therewith for a portion of its length with balloon  17  ( FIG. 1 ), with the stent  30  being carried over the balloon and unidirectional bending member portion. A portion of the unidirectional bending member  50  extends sufficiently distal to the payload in order to orient the device and payload for deployment. The unidirectional bending member is disposed balloon, but not fully around as that would restrict deployment. 
         [0049]      FIGS. 5-10  show a particular embodiment of a unidirectional bending member  50  suitable for use in the present invention, which, as implied by its name, bends substantially unidirectionally. The unidirectional bending member  50  is substantially symmetrical, and more specifically as shown here, is substantially circular in its cross section. “Substantially symmetrical” as used herein refers to the cross section of the unidirectional bending member  50 , at a location of generally uniform material (i.e., not at a location where the member is cut around its perimeter, or in other words, as viewed at the location where lines H-H are present in  FIG. 5C ), and in an unbent state, where (1) the member has substantially equal side lengths, or (2) the member has a substantially equal diameter or radius, or (3) the member is dimensioned to fit within a circle or square, such that at all of the outermost portions of the member&#39;s outer perimeter, it touches the walls of a circle or square. Such an example of (3) would be of a member having a five or six point star shape, the member fitting within a box or circle, with the points (i.e., outer perimeter) all substantially touching the walls of the circle or box, neither substantially extending beyond the walls or substantially falling short of the walls. 
         [0050]    Further, under the conditions described above, the term “substantially symmetrical” excludes members exhibiting major and minor transverse directions, as disclosed in U.S. Pat. No. 6,544,218. 
         [0051]    Unidirectional bending member  50 , is interconnected along its length while divided into a plurality of connected segments with a laser or other suitable cutting apparatus having industrial applicability, which device makes cuts that define the segments therebetween. As shown in  FIGS. 5-10 , the segments are approximately of equal length, although it should be understood that unidirectional bending members having segments of varying length can be produced, and it should be understood that unique bending characteristics can result from cutting the segments into varying lengths. 
         [0052]    The member segments are divided by cutting the member around its circumference at several locations. The circumferential cuts (representatively shown as  52  in the figures) define each segment  54 . In the depicted embodiment, the cuts extend around a portion of the circumference of the member, and in a specific aspect of the invention, the cuts extend around a majority of the member circumference, for example, about 300° of the circumference. Uncut, or solid member portions, are present between the termini  53  of each cut. This arrangement can be viewed in  FIGS. 5A ,  5 B, and  5 C.  FIG. 5B , a view taken along line D-D of  FIG. 5A , where a circumferential cut has been made, shows connector portion  57 , which longitudinally connects the segments of the member  50 .  FIG. 5C , taken along line H-H of  FIG. 5A , shows a substantially solid tube arrangement, interrupted only by the second cuts  55 . That is, a second cut  55  axially extends in the longitudinal direction of the member axis at the termini of each circumferentially-extending cut  52 . As shown, there are a pair of second, axially extending cuts  55  for each circumferentially extending cut  52 . The solid member portions between the cuts are characterizable as isthmus-like connectors  57 . The isthmus-like connectors  57  maintain member interconnectedness from end to end of the member. 
         [0053]    As specifically shown in  FIGS. 7-10 , the tube flexes or bends around the isthmus-like connectors  57 , thereby positioning such connectors on the interior, or short side of the bend. Likewise, the circumferential cuts  52  open during bending on the exterior, or long side, of the bend. Also, during bending, the longitudinally extending cuts  55  open slightly, as shown in  FIG. 9 , relieving stress at the termini  53 . (In  FIG. 10 , a guidewire (unnumbered) can be seen through the openings the cuts  52 , passing though the unidirectional bending member. In addition, the longitudinally extending cuts reduce the tendency of the tube to bend opposite to the desired direction. (That is, the longitudinally extending cuts reduce the number of circumferential cuts necessary to impart sufficient flexibility to the tube. Thus, the reduction in number of circumferential cuts can reduce the possibility of a reverse bend from occurring in the tube due to closure of the numerous gaps formed by the cuts. 
         [0054]    In the aforedescribed arrangement, the bending member can bend only unidirectionally, that is, in only one direction, which is around the interconnections. Also, the connectors  57  are sufficiently stiff so as to prevent the tube from bending such that interconnections are positioned on the long side of the bend, which is undesirable. 
         [0055]    The manner in which the unidirectional bending member  50  bends facilitates orientation of the device as it travels through (1) curves or bifurcations in the vessel, (2) curves or bends in the guidewire, or (3) other eccentricities located within the vessel that force the tube into a curved path. So long as the unidirectional bending member possesses a sufficient degree of freedom to rotate, it will assume the path of least resistance as it travels through the vessel, and thereby rotate/orient itself to conform to the bend in the path of the unidirectional bending member. 
         [0056]    By way of alternative, the tube of the embodiments shown in  FIGS. 5-10  can be provided with a longitudinal cut that runs for substantially the entire length of the tube. While a longitudinal cut need not be present on the tube, and thus is not necessary to the invention, the provision of the longitudinal slot reduces the extent to which the tube is cut circumferentially as well as the number of circumferential cuts required. Thus, providing a longitudinal cut can result in improved production efficiency. 
         [0057]    In a further unidirectional bending member embodiment, an arrangement similar to the laser cut tube can be provided by forming a tube from a welded segment of a helical coil, as shown in  FIG. 11 . That is, the tube  50 ′ is cut helically, akin to a coiled ribbon, and the spaces between the helical cuts  90  are welded closed with solder or the like (numerically designated as  95 ) on one continuous, axially extending segment, located on one tube side. The welds link together adjacent turns of the helix. As with the aforedescribed arrangements, the tube flexes or bends around the welds, thereby positioning such connectors along the inside of the bend. The outside of the tube opens along the helical cut that wraps around the circumference of the tube. 
         [0058]    In one particular aspect of the present invention, the segments are formed from spring segments that are welded together. 
         [0059]    In yet another arrangement, the unidirectional bending member need not be provided with cuts and connectors, but instead can be configured of a non-segmented tube in which unidirectional flex capability is imparted by embedding a component within the tube wall to arrange for a preferred direction of bending. Alternatively, the component can be positioned on the surface of the tube to effect the preferred direction of bending. For example, as shown in  FIG. 12 , a fibrous material  60  can be embedded within the wall of the tube over at least a portion of the circumference and length thereof. The tube will exhibit greater stiffness in the regions where such fibers are embedded, when the embedded fibrous material is a stiffness-imparting material. Such a stiffness-imparting material  60  could be an array of metal wires, thereby resisting bending in the direction extending across the axis of the fibers. Conversely, in regions  62  where no fibers are present, or regions  63  where only a relatively small number of fibers are present (see  FIG. 13 ), then the tube will exhibit an inclination to bend across the tube in such regions. It should be understood that where the density of the stiffness imparting fibers is relatively high, then greater stiffness would be exhibited in that region. In yet another arrangement, shown in  FIG. 13 , the fibers are embedded in the wall of the tube around its circumference; however, the density of such fiber varies around the circumference, so that segments of the tube circumference having a fibrous density less than other segments of the tube exhibit a tendency to flex. When at least two of such segments having a lesser fibrous density are aligned across the tube from each other, then the tube shall exhibit a preference to bend and flex through those regions of lesser fiber density. 
         [0060]      FIGS. 14A-14F  illustrate additional embodiments of the unidirectional bending member. In  FIG. 14A , the unidirectional bending member is provided with a single region of high axial stiffness in relation to the remainder of the circumference. In  FIG. 14B , the tube is provided with a single region of low axial stiffness in relation to the remainder of the circumference.  FIG. 14C  shows a tube in which regions of high axial stiffness are positioned 180° apart from each other.  FIG. 14D  shows a tube in which regions of high and low axial stiffness alternate at 90° orientations.  FIG. 14E  shows a tube in which regions of low axial stiffness are positioned 180° apart from each other.  FIG. 14F  shows a tube in which axial stiffness increases from high to low (or vice versa) as tube circumference is traversed. 
         [0061]    In yet another exemplary embodiment, shown in  FIG. 15  the unidirectional bending member  50  can be made to bend in a preferred direction by providing a shaft  11 ′ in which a preferential bending direction is created by positioning and configuring the internal lumens  14 ′ and  18 ′,  140 ′ and  180 ′ within walls  160 ′ of shaft  11 ′ to provide for a preferred bending direction of the outer tube. For example, the lumens can be arranged around the inner circumference of the outer tube to provide flexibility in a desired direction. If such tubes provide stiffness, then the unidirectional bending member would be constrained against bending through the inner tubes. However, by selectively omitting an inner tube from a location along the inner circumference would remove constraint against bending through that location, and hence create a preferred direction through which the tube can bend. 
         [0062]    Also, chemical, electrical or mechanical means can be used to modify unidirectional bending member stiffness so the unidirectional bending member can be transversely displaced, resulting in a preferred bending orientation. Material phase changes, changes in modulus, or changes in yield stress can be electrically induced in the tube in order to create a preferred bending direction and orientation. Likewise, a component can be present in the unidirectional bending member construction for inducing an axial shift or displacement in the device. 
         [0063]      FIG. 16  illustrates a vessel anatomy having a main branch bend and a side branch off the outside of the main branch bend.  FIG. 17  illustrates a vessel anatomy having a main branch bend and a side branch off the inside bend on the main branch. It should be understood that the device of claim  1 , utilizing the unidirectional bending member embodiments of  FIGS. 5-15 , can deploy a payload, such as a stent, to different branch arrangements, such as the ones shown above. That is, the unidirectional bending member can be oriented, via tube rotation, to deploy payload facing (or properly oriented with respect to) the side branch ostium, regardless of whether the side branch is positioned on the inside or outside of the bend in the vessel. 
         [0064]    Specifically, as shown in  FIG. 4 , an arrangement is shown that is well suited for delivery of payload to the main branch of a bifurcated vessel. In this case, the unidirectional bending member  50  is carried over the main branch guide wire  33 , with both main branch guide wire  33  and unidirectional bending member  50  passing through the balloon  17  (provided with appropriate lumen for guidewire). Further, stent  30  is carried over these components. At around the midpoint of the stent  30 , the side branch guide wire  32  exits through the side branch guide wire exit port  29  and passes through the side wall of the stent  30 , and into side branch of the bifurcated vessel. 
         [0065]    The catheter can be properly oriented when the unidirectional bending member at the distal end of the catheter bends and rotates (as necessary), as the unidirectional bending member passes through the vessel bend. The device configures itself when the unidirectional bending member rotates, with the stent for deployment in the main branch and the side branch guidewire exit port orient to face the side branch ostium, so the side branch guidewire can be passed into the side branch. 
         [0066]    As shown in  FIG. 4 , and drawing upon the embodiments of  FIGS. 5-10 , A denotes the location on the unidirectional bending member  50  where the member is interconnected, such as by connections  57 . B denotes the location where the unidirectional bending member  50  is open (i.e.—element  52  previously discussed). Thus, in this particular orientation of the device, mindful that in  FIG. 4  the proximal end of the member  50  is coming out of the page, the member will bend rightward, with side branch guidewire positioned to extend into a side branch on the outside of the bend, as depicted in  FIG. 15 . 
         [0067]      FIG. 4A  shows what is essentially the opposite of the  FIG. 4  arrangement, in which the tube has oriented itself with the connected side A on the left side of the figure, and the open side B on the right side of the figure. In this particular orientation of the device, with the proximal end of the member  50  coming out of the page, the member will bend leftward, with side branch guidewire positioned to extend into a side branch on the inside of the bend, as depicted in  FIG. 16 . 
         [0068]    Furthermore, is readily appreciable that implantation within the side branch can be similarly achieved, owing to the versatility of the device. For example, as shown in  FIG. 4B , by passing the main branch guide wire  33  through the flex tube  50  (with same positioned exterior to the payload), with the balloon  17  and side branch guidewire  32  within the payload (stent)  36 , the device can be properly oriented by allowing the flex tube to rotate the distal end of the device as the flex tube passes through the bend in the vessel. With this arrangement, the stent can be passed into the ostium of the side branch and then deployed in the side branch. 
         [0069]    It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.