Abstract:
A guide wire including a lubricous distal portion and a less lubricous intermediate portion proximal of said distal portion. One guide wire provides a highly lubricous distal portion with a hydrophilic layer and a less lubricous intermediate portion with a hydrophobic layer. Another guide wire provides a lubricous distal portion with a polymer tip that is itself hydrophilic. Yet another guide wire provides a less lubricous intermediate portion using a stainless steel coil helically wound around the tapering intermediate portion. The coil is preferably coated with a hydrophobic coating such as PTFE or silicone. The coil can either abut the distal portion proximal end or extend into the distal portion interior.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to intravascular guide wires. In particular, the present invention relates to guide wires having a lubricous hydrophilic tip and a less lubricous intermediate portion proximal the distal tip.  
       BACKGROUND OF THE INVENTION  
       [0002]     Guide wires are used in various procedures within various conduits in the body. In particular, they are used in Percutaneous Transluminal Coronary Angioplasty (PCTA) and other coronary procedures. This can involve inserting a guide wire through an incision in the femoral artery near the groin, advancing the guide wire over the aortic arch, into a coronary artery, and across a lesion to be treated. Guide wires can be inserted directly into the vasculature or within a guide catheter. The distal end of the guide wire ultimately lies directly within the vasculature.  
         [0003]     Guide wires serve to guide devices into position for both therapeutic and diagnostic purposes. For this to happen, the guide wire itself must be properly positioned. This is difficult, as it involves moving a wire tip through a narrow opening within a narrow vessel, from 180 centimeters away. This task can be especially difficult as the guide wire must be extremely flexible at the distal end to enable the guide wire tip to enter vessel branches at various angles. The extreme flexibility can come at the expense of axial or rotational strength. Improved responsiveness to remotely applied forces, both rotational and axial, has been provided by reducing friction along the guide wire length. In particular, providing a highly lubricous guide wire distal region of about 12 inches has proven advantageous in maneuvering guide wires through the arteries to reach the site of blockage. Having this same lubricous coating on the tip of the wire has been advantageous in making the wire perform better in finding small openings in the blockages and crossing them.  
         [0004]     Once the guide wire tip is in position, devices including catheters are advanced into position over the guide wire and withdrawn over the guide wire. Such catheter movement acts upon, and tends to move, the guide wire contained within. This can tend to dislodge the guide wire tip. Minor patient movement including breathing also acts to move the guide wire as does handling of the guide wire proximal portion extending from the patient. Dislodging the guide wire tip may require repositioning the guide wire, with the attendant time and effort. Once in position, therefore, stability and resistance to applied forces is preferred over the initially desirable ease of move ment and responsiveness to applied forces.  
         [0005]     What is desirable and has not been provided is a guide wire easily maneuvered into position across a tight lesion, yet providing stability and resistance to movement once the guide wire is in position.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention provides a guide wire having a highly lubricous distal portion, followed proximally by a less lubricous intermediate portion, followed proximally by a proximal portion. The guide wire includes a core member within, preferably formed of metal and having a proximal constant cross section portion, followed distally by a tapered portion, followed distally by a reduced cross section portion. The tapered portion can have multiple tapers. The distal end of the reduced cross section portion is preferably flattened into a ribbon, providing greater flexure in one plane. A preferred core has a circular cross section in the proximal and tapered portions. One guide wire embodiment has a intermediate and distal portion length totalling about 12 to 14 inches. A preferred length for the distal portion is about 1 to 3 centimeters.  
         [0007]     A preferred guide wire achieves a lubricous distal portion by having a hydrophilic surface in the distal portion. A less lubricous intermediate portion is achieved by having a hydrophobic surface in the intermediate portion. The hydrophilic surface has a very low coefficient of friction when placed against an artery wall in a blood filled artery. The hydrophobic surface has a higher coefficient of friction against the artery wall.  
         [0008]     The present invention distal portion can be formed of a polymer not necessarily hydrophilic, but having a hydrophilic coating thereover. The intermediate portion can be formed of a hydrophobic polymer sleeve over the core wire or a polymer sleeve over the core wire having a hydrophobic coating. In another embodiment, the intermediate portion can include a coil around the core wire, the coil preferably having a hydrophobic coating. The coil wire abuts the distal portion in one embodiment, and is embedded beneath the distal polymer in another embodiment. In yet another embodiment, the distal portion includes a distal tip having a proximally tapered proximal portion, and the coil wire distal end contacts the distal tip in the tapered portion, thereby centering the coil.  
         [0009]     The present invention provides the ability to cross tight lesions by having a highly lubricous, low friction, distal portion, which is relatively easy to slide through a narrowed vessel region. The extremely lubricous portion is limited to a shorter length relative to previous devices. A preferred length is about 1 inch. The lubricity is limited to the portion where the extreme lubricity is most needed, the distal portion. Lower friction is required in the extreme distal portion because the core member there is narrower and therefore weaker, not having the strength of the more proximal portion to handle being axially pushed from the proximal end against obstructions. Low friction is also required in this portion because this is the portion that is required to initially cross an extremely tight lesion, something not required of the more proximal portion. The low friction facilitates the wire tip first piloting into the small remaining opening in the lesion and then crossing the lesion without buckling the wire.  
         [0010]     To counteract the highly lubricous, low friction distal portion, the present invention deliberately provides a less lubricous, higher friction intermediate portion, proximal of the distal portion. The intermediate portion can lie against an artery wall, or guide catheter wall, “anchoring” the guide wire. The present invention, by having an anchoring portion proximal of the distal portion, provides resistance to forces such as catheter movement over the guide wire, which could act to dislodge the guide wire tip from its desired position.  
         [0011]     While the anchoring portion friction will not prevent all movement of the guide wire, it provides sufficient static friction to resist unintentional movement due to either catheter movement or patient movement. In this way, a series of minor forces acting on the guide wire proximal portion, if below the threshold of static friction presented by the anchoring portion, will not be translated into a series of minor movements of the guide wire distal tip. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a fragmentary, side cross-sectional view of a guide wire, in accordance with the present invention, having a coil in the intermediate portion;  
         [0013]      FIG. 2  is a fragmentary, side cross-sectional view of a second embodiment of a guide wire having a core wire shown in phantom;  
         [0014]      FIG. 3  is a fragmentary, side cross-sectional view of a third embodiment of a guide wire having a coil extending into the distal tip;  
         [0015]      FIG. 4  is a fragmentary, side cross-sectional view of a fourth embodiment of a guide wire having a two part coil extending into the distal tip; and  
         [0016]      FIG. 5  is a fragmentary side cross-sectional view of a fifth embodiment of a guide wire having a proximally tapered polymer tip and a coil sitting on the taper. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]      FIG. 1  illustrates a fragmentary, side cross-sectional view of a guide wire  20  having a distal portion  22 , an intermediate portion  24 , and a proximal portion  26 . Guide wire  20  has a surface extending the length thereof, as indicated at  21 . The length of distal portion  22  is indicated by arrows  40  and the length of intermediate portion  24  by arrows  44 . Guide wire  20  includes an elongate core member  28  having a constant cross section portion  30 , a tapered portion  32  and a reduced cross section portion  34 . Core member  28  preferably has a circular cross section in portions  30  and  32 . The intermediate tapered portion  32  may comprise a single taper or a series of tapers with regions of constant diameter in between. Core  28  is preferably formed from high tensile strength stainless steel wire or a super-elastic alloy such as Nitinol.  
         [0018]     Core reduced cross section portion  34 , illustrated lying within a distal portion  22 , provides extreme flexibility to the guide wire where needed, at the extreme distal end. Reduced cross section portion  34  is preferably flatter in one dimension than another, forming a ribbon, providing more flexibility in one dimension than another. Tip flexibility is desirable for insinuating the guide wire into ever more distal and tortuous coronary arteries. The embodiment of distal portion  22  illustrated can include a distal tip  38  encasing core reduced cross section portion  34 . In a preferred embodiment, distal tip  38  includes a polymeric material. Distal tip  38  is preferably radiopaque to allow for tracking the tip position using fluoroscopy. In one embodiment, tip  38  includes polyurethane and is loaded with tungsten, 85 to 90 percent by weight, for radiopacity. In one embodiment, a polyurethane sleeve forms distal tip  38 , which can be between about ½ and 7 centimeters in length. In a preferred embodiment, tip  38  is between 1 and 3 centimeters in length.  
         [0019]     Distal portion  22  according to the present invention is lubricous. In a preferred embodiment, distal portion  22  is extremely lubricous. In one embodiment, the lubricity is provided by having a hydrophilic material at the surface of distal portion  22 . A hydrophilic surface makes the surface highly lubricous when in contact with a water based fluid such as blood. In the embodiment illustrated in  FIG. 1 , lubricity is provided by a distal layer  36  over reduced diameter portion  34  and distal tip  38 . A hydrophilic coating over the guide wire presents very little friction when sliding through the artery interior. This provides ease of crossing tight lesions, allowing difficult and distally remote lesions to be treated. In one embodiment, distal layer  38  includes a polyvinylpyrrolidone (PVP) coating. In another embodiment, distal layer  38  includes a polyethyl maleic anhydride coating. In a preferred embodiment, distal portion  22  is about 0.014 inches in diameter.  
         [0020]     Proximal of distal portion  22  is intermediate portion  24  which has a lubricity less than that of distal portion  22 . In a preferred embodiment, intermediate portion  24  has length  44  of about 20 to about 30 centimeters. In one embodiment, intermediate portion  24  is about 28 centimeters long and about 0.0130 to 0.0135 inches in diameter. Guide wires used to deliver stiffer devices may have a shorter intermediate region to make the wire more supportive. In these cases intermediate portion  24  may be as short as 3 centimeters. In the embodiment depicted in  FIG. 1 , intermediate portion  24  includes tapered core portion  32  which is encased in a coil  42 . A preferred coil is formed of stainless steel and coated with hydrophobic coating. A preferred hydrophobic coating is PTFE or silicone. Coil  42 , by presenting a series of wires oriented transversely to the axial direction of guide wire movement, provides resistance to axial movement. The coil also provides increased pushability and kink resistance for tapered core portion  32 . In compression, the coil provides axial strength over the length of tapered core portion  32  which decreases in strength with decreasing core cross section. The distal end of coil  42  can be attached to core  28  using solder or adhesive. The proximal end of coil  28  is preferably secured to core  28  by adhesive.  
         [0021]     Intermediate portion  24  provides a higher friction anchoring portion to maintain the position of distal portion  22 . If too much of the guide wire is extremely lubricous, the distal tip can be difficult to fix exactly in position, as catheter advancement and retraction over the guide wire can apply forces to the guide wire, tending to move the guide wire tip. Patient movement, including breathing, can also translate into movement at the guide wire distal tip. By providing an intermediate region having a less lubricous surface, an intermediate anchoring region is provided, which presents friction against the vessel wall, presenting resistance to forces that would otherwise be translated into movement at the distal tip. While the intermediate anchoring portion cannot resist all forces applied to the guide wire and prevent all tip movement, the static friction of the anchored guide wire intermediate portion does provide a threshold barrier to lower level forces. Thus, a series of small forces is not necessarily translated into a series of low level movements of the guide wire tip.  
         [0022]     Proximal portion  26  in a preferred embodiment, extends to the guide wire proximal end. Included in proximal portion in  FIG. 1  is constant cross section core portion  30 . In a preferred embodiment, proximal portion  26  includes a stainless steel wire about 0.013 inches in diameter and has a polytetrafluoroethylene (PTFE) coating. In one embodiment, proximal portion  26  is less lubricous than intermediate portion  24 . In another embodiment, proximal portion  26  is more lubricous than intermediate portion  24  but less lubricous than distal portion  22 .  
         [0023]      FIG. 2  illustrates another embodiment of the invention, guide wire  120 , having a proximal portion  126 , an intermediate portion  124 , and a distal portion  122 . Distal portion  122  is preferably about ½ to 7 centimeters in length, and intermediate portion  124  can be 1 to 15 inches in length and is preferably about 8 to 12 inches in length. Within guide wire  120  is a core  128  having a constant diameter portion  130 , a tapered portion  132  and a reduced diameter portion  134 . Core  128  can be substantially similar to core  28  discussed with respect to  FIG. 1 . Guide wire  120  has a lubricous distal portion  122  and a less lubricous intermediate portion  124 . In the embodiment depicted in  FIG. 2 , distal portion  122  includes a distal tip  136 . Distal tip  136  can be similar to distal tip  36  in  FIG. 1 . In some embodiments, distal tip  136  is formed of polyurethane, and coated with hydrophilic coatings as discussed above with respect to  FIG. 1 . Distal tip  136  is preferably radiopaque to allow for tracking the tip position using fluoroscopy. In one embodiment, tip  136  includes polyurethane and is loaded with tungsten, 85 to 90 percent by weight, for radiopacity. Distal tip  136  is preferably more radiopaque than intermediate portion  124 .  
         [0024]     Intermediate portion  124  provides a less lubricous portion proximal to lubricous distal portion  122 , as in the embodiment of  FIG. 1 , but without requiring a coil. The lower lubricity is provided by having a hydrophobic surface. This can be provided with both hydrophobic sleeves and hydrophobic coatings over sleeves that are not necessarily hydrophobic. Sleeve  142 , illustrated encasing tapered core portion  132 , can be formed of a hydrophobic polymer. Hydrophobic polymers include fluorinatedethylenepropylene (FEP) and polytetrafluoroethylene (PTFE). Intermediate portion  124  can also be formed of a material such as polyether block amide (PEBAX) or polyethylene coated with a low friction, hydrophobic coating such as silicone, paralene, PTFE, or FEP. Guide wire  120  can be formed by sleeving tube  142  over core  128 , bonding the tube in place at its proximal end with adhesive, shrinking a suitable distal tip material over reduced diameter core portion  134 , and bonding the distal portion of sleeve  142  to the proximal portion of the distal tip. Another suitable method includes heat shrinking a polymeric tube over core  128 , grinding the tube to an approximate diameter of about 0.0130 to 0.0135 inches, then selectively coating intermediate portion  124  and possibly distal portion  122  also, with one of the hydrophobic coatings, and then coating distal portion  122  with one of the previously described hydrophilic coatings.  
         [0025]      FIG. 3  illustrates yet another embodiment of the invention, a guide wire  220 , having proximal portion  226  followed distally by intermediate portion  224  followed distally by distal portion  222 . A core  228  proceeds distally from a constant diameter portion  230  to a tapered portion  232  to a reduced diameter portion  234 . Intermediate portion  224  includes a coil  242  surrounding the tapered portion of the core, with coil  242  proceeding distally from a constant diameter portion  241  to a tapered portion  243  to a reduced diameter portion  244 . Core  228  is preferably flattened into a ribbon shape in reduced diameter portion  244 . Reduced diameter portion  244  is embedded within distal tip  238  when the polymer tip is shrunk onto the wire. In this embodiment, neither solder nor adhesive are required to secure the distal end of coil  242  to core  228 . The proximal end of coil  242  can be secured to core  228  by soldering. Distal tip  238  can be coated with a hydrophilic layer  236  as discussed above with respect to the embodiment of  FIG. 1 . The materials of distal tip  238  and layer  236  can be similar to those of distal tip  38  and layer  36 .  
         [0026]      FIG. 4  illustrates yet another embodiment of the invention, a guide wire  320 , having a proximal portion  326 , followed by an intermediate portion  324 , followed distally by a distal portion  322 . A core  328  proceeds distally from a constant diameter portion  330  to a tapered portion  332 , to a reduced diameter portion  334 . A coil  342  surrounds core  328  over the intermediate and distal portions. In the embodiment shown, coil  342  is formed of a proximal coil  323  and a distal coil  325  soldered together at  340 . Proximal coil  323  is preferably formed from a less radiopaque material such as stainless steel. This coil can be coated with a hydrophobic coating such as PTFE. Distal coil  325  is preferably formed of a more radiopaque material such as platinum. Combined coil  342  is attached to core  328  proximally with solder at  341  and distally with either solder or welding at  338 . A hydrophilic coating  336  is applied to the distal portion of distal coil  325  in one embodiment by first applying a Tie layer polymer such as polyurethane by dip or spray coating, followed by applying a hydrophilic coating over the Tie layer coating. The hydrophilic coating can be one of the coatings described previously with respect to guide wire  20  in  FIG. 1 .  
         [0027]      FIG. 5  illustrates yet another embodiment of the invention, a guide wire  420  having a proximal portion  426 , followed by an intermediate portion  424 , followed distally by a distal portion  422 . A core  428  proceeds distally from a contact diameter portion  430  to a tapered portion  432 , to a reduced diameter portion  434 . A distal tip  436 , preferably formed of a polymeric substance, surrounds core reduced diameter distal portion  434 . Distal tip  436  includes a tapered portion  437 , which tapers proximally toward core tapered portion  432 . Guide wire  420  includes a coil  442  which extends distally over core tapered portion  432 . Coil  442  has a distal end  443  which contacts and terminates within distal tip tapered portion  437 . Coil  442  is thus always centered on core  428 , as transverse movement of coil distal end  443  is opposed by distal tip tapered portion  437 . Tip  436  can be heated to embed end  443  therein.  
         [0028]     While use of the present invention can be described with reference to any of the embodiments, the embodiment of  FIG. 1  is selected for further illustration. In use, core reduced diameter portion  34  can be bent by the treating physician, prior to insertion into the patient. Having a bent distal tip allows orienting the tip for insertion into arteries by rotating the proximal end of the guide wire, which rotates the bent distal tip toward arterial side branches. The guide wire can be advanced through a guide catheter or directly through the vasculature. After having advanced the guide wire into a coronary artery such as the left coronary artery, the guide wire is maneuvered into selected smaller arteries. In attempting to insinuate the distal most portion of the guide wire into smaller arteries, the lubricous tip provides easier initial advancement into the artery. When a lesion is to be crossed, lubricous distal portion  22  provides low resistance to axial movement into and through a narrow passage. Low resistance is advantageous as there is less tendency for core reduced diameter portion  34  to kink or buckle when pushed by the treating physician from the extreme proximal end.  
         [0029]     Once distal portion  22  is across the lesion, it is highly preferred that the guide wire tip position not change, despite minor changes in proximal handling of the guide wire, movement of other devices over the guide wire, patient breathing, blood flow, and minor changes in frictional conditions along the guide wire length. The present invention allows a guide wire to resist these forces by having intermediate portion  24  lie against and be “anchored” to the vessel or guide catheter wall, presenting a higher quantity of static friction that must be overcome to dislodge the guide wire distal tip, than presented with wires having longer lubricous distal surfaces. The present invention thus makes it less likely that the guide wire will move inside the artery unless the physician is directly intending to move it.  
         [0030]     The combination of lubricous distal portion and less lubricous intermediate portion thus serves to promote ease of distal tip advancement across tight lesions while stabilizing the distal tip position once placed, allowing other devices to be accurately guided into position by the guide wire.  
         [0031]     Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The inventions&#39;s scope is, of course, defined in the language in which the appended claims are expressed.