Abstract:
A wire guide for feeding a medical catheter through the body passage of a patient to a distant target site within the body has a variably flexible distal portion. The distal portion facilitates threading the guidewire in a tortuous path through acute bends at branch junctions in the body passages of the patient. The wire guide end is able to feed into very delicate vessels such as ventricles of the brain and the spinal canal without puncturing the wall or damaging organs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/056,686 filed on Sep. 29, 2014, entitled “WIRE GUIDE FOR TRAVERSING BODY PASSAGES,” the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to medical devices and, more particularly, to medical devices employed for navigating tortuous body passages atraumatically. 
       BACKGROUND OF THE INVENTION 
       [0003]    Wire guides are used in a variety of medical procedures involving the vasculature of a patient. 
         [0004]    Wire guides can be described as elongated flexible members used to provide a path along which another medical device can be moved. For example, the path provided by the wire guide can be used to navigate a medical device, such as a catheter, through a body vessel. 
         [0005]    The catheter and wire guide are often highly flexible in order to traverse the tortuous body passages en route to the treatment location. Such wire guides are advanced through the circulatory system by applying a torque to the proximal end of the wire guide at an external site. In this example, the wire guide has sufficient column strength to allow the distal end of the wire guide to be manipulated from the external access site. 
         [0006]    Current catheter wire guide designs attempt to meet these requirements by incorporating a number of features designed to increase the flexibility of the distal end of the wire guide while maintaining torsional rigidity. Such designs may include a tapered distal end region of the wire guide. 
         [0007]    However, such tapering may reduce the torsional rigidity of the wire guide, resulting in additional manufacturing steps which may be more time consuming or complex. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the present invention provide a wire guide having enhanced torsional rigidity, enhanced flexibility, and reduced manufacturing complexity. 
         [0009]    According to one aspect of the present invention, a wire guide to access a body vessel of a patient is provided. The wire guide comprises a cannula having a proximal end and a distal end. The cannula has a first lumen formed through the proximal and distal ends, and the cannula has a plurality of cuts to allow the cannula to extend, defining variable rigidity. The wire guide also comprises a flexible portion comprising a covering and a plurality of members disposed in the covering. The covering has an open end extending to a closed end. The open end is attached about the distal end of the cannula. The plurality of members includes a first body attached to the distal end of the cannula and a second body disposed at the closed end of the covering. The members have apertures defining a second lumen in axial alignment with the first lumen. The wire guide also comprises a core wire having a distal tip and being slidably disposed through the first lumen and the second lumen. The distal tip is attached to the second body. 
         [0010]    In accordance with another aspect of the present invention, one embodiment comprises an assembly of the wire guide for accessing a body vessel. The assembly includes the wire guide and an outer sheath having a proximal section extending to a distal section. The outer sheath has a sheath lumen formed therein through the proximal and distal sections. The wire guide is disposed within the sheath lumen and the outer sheath is configured to translate axially relative to the wire guide. 
         [0011]    In accordance with yet another aspect of the present invention, a method of accessing a body vessel is provided. The method comprises providing the assembly, introducing the outer sheath to the body vessel, inserting a wire guide through the outer sheath, varying the rigidity of the cannula, and navigating the wire guide through the body vessel to a treatment location. 
         [0012]    Further aspects, features, and advantages of the invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of the wire comprising a cannula having a plurality of cuts in accordance with one embodiment of the present invention. 
           [0014]      FIG. 2  is a perspective view of the wire guide comprising a core wire slidably disposed through a second lumen in accordance with one embodiment of the present invention. 
           [0015]      FIG. 3  is a breakaway view of the flexible portion taken along line  108  in accordance with one embodiment of the present invention. 
           [0016]      FIG. 4  is a side view of one member of the plurality of members in accordance with one embodiment of the present invention. 
           [0017]      FIG. 5  is a cross sectional view of the flexible portion of wire guide in accordance with one embodiment of the present invention. 
           [0018]      FIGS. 6A and 6B  are partial side views of the plurality of cuts in the cannula in accordance with one embodiment of the present invention, wherein the cuts are unextended and extended respectively. 
           [0019]      FIGS. 6C and 6D  are partial side view of the plurality of cuts in the cannula in accordance with another embodiment of the present invention, wherein the cuts are unextended and extended, respectively. 
           [0020]      FIG. 7  is a partial sectional view of the flexible portion having a first body in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In this description, when referring to a deployment or treatment assembly, the term distal is used to refer to an end of a component which in use is furthest from the clinician during the medical procedure, including within a patient. The term proximal is used to refer to an end of a component closest to the clinician and in practice in or adjacent to an external manipulation part of the deployment or treatment apparatus. 
         [0022]    The novel wire guide  134  includes a cannula portion  100 , a flexible portion  108 , and a core wire  128 . The cannula portion  100  includes a series of cuts  106  to provide it with variable length. The flexible portion  108  includes a number of spheroidal members  112  that are displaced longitudinally at the distal end of a core wire  128  and within a covering  110 . The core wire  128  is displaced internally to both the cannula portion  100  and the beaded portion  108 , passing through a first lumen  104  within the cannula  100 , and a second lumen  126  defined by the apertures  124  in each of the spheroidal members  112 . The core wire  128  is affixed to the distal-most member  122 . The members  112  are separated from one another by variable gap distances  138  manipulated to alter the flexibility of the distal portion of the core wire. The core wire  128  can flex at points within the gaps  138  between the member  112  which allows the distal end  108  of the wire guide to bend at branch junctions and to conform to the curvature in the vessel duct. The member  112  can be fixed to the core wire  128  or they can move freely along the distal portion of the core wire  108 . Also, member  112  freely sliding along the core wire  128  may be compressed against one another to control the flexibility and curvature of the distal portion  108  by manipulating the proximal end  136  of the core wire and inducing varying amounts of tension in cannula portion  100 , and thereby the flexible portion  6 , of the wire guide  134 . Finally, the covering element  110  is disposed about the beaded portion  108  of the wire guide  134  and extends from a closed end  116  about the distal-most member  122  to the distal end of the cannula portion  102 , where it is affixed about  118  the distal end of the cannula  102 . An insertion tube is provided for initially feeding the flexible wire guide end into the body passage.[LK 1 ] 
         [0023]    A first embodiment of the invention can be understood with reference to  FIG. 1 . The catheter wire guide  134  has a core wire  128  having a length to reach a distant target site when fed percutaneously from outside the body into the lumen of a bodily duct. The wire guide has a proximal end  136  that remains outside the body and is manipulated by a physician. Generally, the core is flexible so as to be capable of threading through a branched bodily duct network along a tortuous path. The thickness, shape of cross section, and materials of construction of the core wire can vary along the length to provide different mechanical properties, such as flexibility and torsional strength. Preferably, near or adjacent the proximal end, the core wire may be relatively stiff. Moreover, the core wire near the proximal end may be relatively stiff. Preferably, the proximal portion of the wire guide is less flexible because it usually resides in larger diameter, slightly curving sections of the duct network near the entry point. Also the increased stiffness near the proximal end facilitates transmission of torque along the full length of the wire guide to aid in steering the tip at the distal end. Preferably, wire guide flexibility increases along the length toward the distal end. 
         [0024]    Throughout this specification reference will be made to a plurality of cuts  106  and a plurality of members  112 . Unless otherwise stated, the term “cuts” shall hereinafter refer to a plurality of incisions on the cannula  100  which may be in any patterns designed to allow for longitudinal expansion and contraction of the cannula  100 . Additionally, the term “members” shall hereinafter refer to a plurality of structures disposed between the distal end of the cannula  102  and the distal tip of the core wire  130 ; where the members  112  can be any shape with rounded edges that allow for movement against one another and smooth passage through the body duct. For example, each of the plurality of members  112  could be spherical, ovoid, ring-like, or any combination of such shapes or any other such rounded shape. The embodiments of this invention include at least two members. The at least first member  120  is affixed to the distal end of the cannula  102 , and a second member  122  is affixed to the distal tip  130  of the core wire  128  at an attachment region  132 . 
         [0025]    At its distal end, the core wire terminates at tip  130  on which is affixed a second member  122 . Because the second member  122  at the distal tip of the core wire  130  leads the wire guide through the bodily duct, the second member  122  is a blunt form to reduce the risk of wall penetration. The second member  122  can have a spheroidal shape. The term “spheroidal” means that the shape can be imperfectly spherical as well as exactly spherical. Spheroidal shapes can include spherical, elliptical, ovoid, and hemi-spheroidally-ended cylindrical shapes, as well as ring-like structures and round-ended semi-cylindrical structures. If conical, the forward and trailing ends should be blunted to remove any sharp edges which could provide a risk of penetration of the duct walls. 
         [0026]    To assure that the second member  122  does not separate from the core wire  128 , the second member  122  should be securely attached to the distal tip  130  of the core wire. The method of attachment is not critical to operation of the invention. For example, the second member  122  and the core wire  128  could be manufactured as a single piece, the second member  122  thereby being integral to the core wire  128 . Alternative exemplary methods of attachment including cementing, thermally fusing, or crimping the second member  122  to the core wire  128 , fastening with clamps, pins and set screws, and any combination of these. 
         [0027]    The flexible portion  108  of the wire guide includes a plurality of spheroidal members  112  positioned sequentially along the core wire  128 . The members  112  are slidably disposed along the core wire  128  such that they can move relative to one another. The flexible portion  108  of the wire guide also includes a covering  110  having a closed end  116  at the distal tip  130  of the core wire, and an open end  114  that extends about, and is affixed to, the distal end  102  of the cannula  100 . The covering  110  encases the members  112 , such that they are prevented from separating from the core wire  128  and drifting through the patient&#39;s vasculature. The members  112  also generally have smooth, rounded surfaces to prevent drag against the covering  110  or the duct walls during wire guide movement within the duct lumen. 
         [0028]    The flexible portion  108  of the wire guide is intended to lead the wire guide into the usually very small duct branches in the far reaches of the network. Consequently, the diameter of the members  112  should be sufficiently small for the flexible portion  108  to slide easily through the narrowest ducts. 
         [0029]    The members  112  are spaced apart along the axis of the core wire  128  by a small distance which creates a gap  138  between adjacent members  112 . The core wire  128  can flex freely in the gaps. Such flexing permits the distal portion to assume suitable curvature to advance the distal end of the device toward the target site through acute curves in a body duct network. Furthermore, the gap  138  between members  112  is variable, and may be reduced such that the members  112  are touching one another, and the wire guide  134  is thereby stiffened. It is important that the flexible portion  108  not be too flexible, as under such a configuration, it could kink and jam within the body duct. 
         [0030]    Members  112  of the novel wire guide will also be defined by a characteristic length. References to “length” should be interpreted to mean the maximum axial dimension of a member, such as the dimension  140  in  FIG. 3 ,  FIG. 4  and  FIG. 5 . The aspect ratio of the members, that is, the ratio of the length relative to the diameter, can also influence the ability of the flexible portion to fold, kink, or jam within the body duct. Members with too great an aspect ratio will cause the flexible portion to function as a straight, rigid rod, rather than a flexible wire guide. While this could be beneficial, in some embodiments, for navigating stenosed regions of the vasculature, such members would be incapable of navigating sharp curves within the patient&#39;s body ducts. Conversely, if the aspect ratio of the members is too small, the members may tend to bunch together and jam in the duct at bends or branch junctions. Therefore, a variety of embodiments are contemplated such that the physician may choose a device with the appropriate flexibility and navigability characteristics for the particular procedure. 
         [0031]    Some or all of the members  112  may also have magnetic properties, radiopaque characteristics, or both. Members with radiopaque characteristics can be seen by using imaging technology known in the art, and can aid physicians in properly placing the wire guide  134  within the body of a patient. With reference to guidance, in some embodiments of the invention, some or all of the members  112  may have magnetic properties as well. In this invention, the term “magnetic” is used to refer to a composition that is a permanent magnet, a paramagnetic material, a diamagnetic material, or any other form of magnetic material. In instances where some or all of the members  112  comprise a magnetic material, the magnetic material can be used to assist a physician in guiding the wire guide  134  through the body of a patient. This may be accomplished by applying attractive or repulsive magnetic fields generated outside the body of the patient to the magnetic members  112  of the wire guide  134 . 
         [0032]    In some preferred embodiments of the invention only repulsive magnetic fields will be applied to members  112  of the wire guide  134  which have magnetic properties. In such cases, since the magnetic field strength falls off exponentially with the distance to the source, very fine control of the flexible portion  108  of the wire guide  134  may be accomplished. 
         [0033]      FIG. 2  provides second view of the embodiment of  FIG. 1 , wherein the cannula  1  has been omitted so that the core wire  128  is visible along with the members  112  disposed about the flexible portion  108  of the wire guide. 
         [0034]      FIG. 3  provides an enlarged view of an embodiment of the invention in which the covering  110  is shown surrounding each of the members  8 , and extending from a closed end  116  at the distal-most end of the second member  122  to the distal end  102  of the cannula  100 , including the entirety of the flexible portion  108 . The covering  110  is further shown to encapsulate a portion of the distal end  102  of the cannula  100 . This portion of the covering is affixed to the cannula  100  by clamping, gluing, bonding or any other electrical, mechanical or chemical means that is known in the art. Furthermore, the first member  120  is affixed to the distal end  102  of the cannula  100  by clamping, gluing, bonding, or any other electrical, mechanical or chemical means known in the art. 
         [0035]      FIG. 4  provides an enlarged view of a single member  112  of an embodiment of the invention in which the members  112  are spherical. The core wire  128  can be seen entering and exiting the apertures  124  defining the second lumen  126  within each member  112 . In this embodiment of the invention, the member  112  may slide along the core wire  128 . In addition, the member  112  in this embodiment can be spheroidal with an axial length  1240  equal to its diameter. This is not limiting, however, as noted earlier, a “spheroidal” member  112  could be any shape that may be imperfectly spherical as well as exactly spherical. Spheroidal shapes can include spherical, elliptical, ovoid, and hemi-spheroidally-ended cylindrical shapes, as well as ring-like structures. 
         [0036]      FIG. 5  depicts a partial section view of an embodiment of the invention in which the structures of  FIG. 4  are incorporated into a more complete depiction of the invention. In this embodiment of the novel wire guide, the wire guide includes a slender core wire  128  extending from a proximal end  136  to a distal tip  130 . The core wire  128  is affixed to the second member  122  at its distal tip  130 . The attachment may be carried out by clamping, gluing, bonding, or any other electrical, mechanical or chemical means known in the art. The cannula  100  is depicted having a first lumen  104  and the members  112  are shown having apertures  124  defining a second lumen  126 . The core wire  128  extends through both the first  104  and second  126  lumens, reaching from the proximal end  136  of the wire guide to the second body  122 . The length of the core wire  128  can vary with each embodiment of the invention, as it will be defined in part by the number of members  112  as well as their axial lengths  140 . More simply said, the length of the core wire  128  will vary with the length of the flexible portion  108  of the wire guide  134 . In addition, the flexible portion  108  of the wire guide  134  can have a variable length in each embodiment, as the amount of tension applied to the core wire  128  will vary the gaps  138  between the members  112 . 
         [0037]    The covering  110  is shown having an open end  114  at the distal end  102  of the cannula and extending around each of the members  112  and terminating in a closed end  116  surrounding the second body  13 . At the distal end  102  of the cannula, the open end  114  of the covering  110  is affixed in by clamping, gluing, bonding, or any other electrical, mechanical or chemical means known in the art. In this embodiment, the distal end  102  of the cannula is bonded to the open end  114  of the covering in a region denoted by the number  118 . 
         [0038]      FIG. 6A ,  FIG. 6B ,  FIG. 6C , and  FIG. 6D  depict partial views of two embodiments of the invention. In each of these diagrams, everything but the cannula  100  is omitted such that two different methodologies of providing cuts  106  to the cannula  100  are depicted. These depictions should not be construed as limiting, however, as they are merely intended to show that there are many methods available to provide the cannula  100  with a series of cuts  106  that create the potential for the cannula  100  to have a variable axial length. 
         [0039]      FIG. 6A  and  FIG. 6B  depict a series of cuts  106  in the cannula  100  such that an “scissors-lift-like” length variation may be accomplished. 
         [0040]      FIG. 6C  and  FIG. 6D  depict a series of cuts  106  in the cannula  100  that spiral about the cannula in such a way that a “slinky-like” length variation may be accomplished. 
         [0041]      FIG. 7  depicts a partial section view of an alternate embodiment of the present invention, wherein the first member  120  has an alternate form, wherein the axial length  140  of the first member  120  has an axial length  140  that is different than its cross sectional diameter  142 .  FIG. 7  further includes the structures of  FIG. 4 , which are thus incorporated into a more complete depiction of the invention. In this embodiment of the novel wire guide, the wire guide includes a slender core wire  128  extending from a proximal end  136  to a distal tip  130 . The core wire  128  is affixed to the second member  122  at its distal tip  130 . The attachment may be carried out by clamping, gluing, bonding, or any other electrical, mechanical or chemical means known in the art. The cannula  1  is depicted having a first lumen  104  and the members  112  are shown having apertures  124  defining a second lumen  126 . The core wire  128  extends through both the first  104  and second  126  lumens, reaching from the proximal end  136  of the wire guide to the second body  122 . The length of the core wire  128  can vary with each embodiment of the invention, as it will be defined in part by the number of members  112  as well as their axial lengths  140 . More simply said, the length of the core wire  128  will vary with the length of the flexible portion  108  of the wire guide  134 . In addition, the flexible portion  108  of the wire guide  134  can have a variable length in each embodiment, as the amount of tension applied to the core wire  128  will vary the gaps  138  between the members  112 . 
         [0042]    The covering  110  is shown having an open end  114  at the distal end  102  of the cannula and extending around each of the members  112  and terminating in a closed end  116  surrounding the second body  122 . At the distal end  102  of the cannula, the open end  114  of the covering  110  is affixed in by clamping, gluing, bonding, or any other electrical, mechanical or chemical means known in the art. In this embodiment, the distal end  102  of the cannula is bonded to the open end  114  of the covering in a region denoted by the number  118 . In this embodiment, the first member  120 , comprises an alternate form, wherein its lumen  126  has a somewhat conical cross section. 
         [0043]    In certain aspects, the present invention provides unique wire guide devices  134  that can effectively traverse tortuous body passages atraumatically. In accordance with some forms of the invention, such wire guide devices  134  are configured to provide variable flexibility to the distal portion  108  of the device. In such devices, the wire guide  134  may include a cannula  100  provided with a series of cuts  106 , a plurality of spheroidal members  112  disposed within a covering  110  and fixed or slidably disposed about a core wire  128 ; the first member  120  being affixed to the distal end of the cannula  102 , and the distal-most member  122  being affixed to the distal tip  130  of the core wire  128 . 
         [0044]    In some forms of the invention, some of the members  112  may be radiopaque to allow for more precise guidance and placement within the vasculature. 
         [0045]    Additionally, in some forms of the invention, some of the members  112  may have magnetic properties such that they may be guided through the vasculature by an externally-applied magnetic field. 
         [0046]    To provide for a smooth external surface of the flexible portion  108 , and to prevent the bead-like structures of this invention separating from the core wire while inside a patient&#39;s vasculature, the entire flexible region of the wire guide is encapsulated within a covering which is closed at its most distal end, and affixed about the distal end of the cannula. 
         [0047]    Although the invention has been described and illustrated with reference to specific illustrative embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope and spirit of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appended claims and equivalents thereof.