Abstract:
A hybrid catheter guide wire includes an elongate solid body having a tapered distal end over which is disposed a tubular section—about which a catheter may be threaded for guidance to a target location in a vasculature passageway of a body. Cuts are formed either by saw-cutting, laser cutting or etching at spaced-apart locations along at least a portion of the tubular section to increase its lateral flexibility, while maintaining its rotational torquability, and to control the direction and degree of flexure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation application of Ser. No. 08/975,769, filed Nov. 21, 1999, which is a continuation-in-part application of Ser. No. 08/653,199, filed May 24, 1996. 
     
    
     
       FIELD OF INVENTION  
         [0002]    This invention relates to a hybrid catheter guide wire apparatus with improved torque and flexure characteristics.  
         BACKGROUND OF THE INVENTION  
         [0003]    Catheter guide wires have been used for many years to “lead” or “guide” catheters to desired target locations in the human body&#39;s vasculature. The typical guide wire is from about 135 centimeters to 195 centimeters in length, and is made from two primary pieces—a stainless steel core wire, and a platinum alloy coil spring. The core wire is tapered on the distal end to increase its flexibility. The coil spring is typically soldered to the core wire at a point where the inside diameter of the coil spring matches the outside diameter of the core wire. Platinum is selected for the coil spring because it provides radiopacity for X-ray viewing during navigation of the guide wire in the body, and it is biocompatible. The coil spring also provides softness for the tip of the guide wire to reduce the likelihood of puncture of the anatomy.  
           [0004]    Navigation through the anatomy is achieved by viewing the guide wire in the body using X-ray fluoroscopy. The guide wire is inserted into a catheter so the guide wire protrudes out the end, and then the wire and catheter are inserted into a vessel or duct and moved therethrough until the guide wire tip reaches a desired vessel or duct branch. The proximal end of the guide wire is then rotated or torqued to point the curved tip into the desired branch and then advanced further. The catheter is advanced over the guide wire to follow or track the wire to the desired location, and provide additional support for the wire. Once the catheter is in place, the guide wire may be withdrawn, depending upon the therapy to be performed. Oftentimes, such as in the case of balloon angioplasty, the guide wire is left in place during the procedure and will be used to exchange catheters.  
           [0005]    As the guide wire is advanced into the anatomy, internal resistance from the typically numerous turns, and surface contact, decreases the ability to advance the guide wire further. This, in turn, may lead to a more difficult and prolonged procedure, or, more seriously, failure to access the desired anatomy and thus a failed procedure. A guide wire with both flexibility and good torque characteristics (torsional stiffness) would, of course, help overcome problems created by the internal resistance.  
           [0006]    Among the approaches suggested in the prior art for increasing the flexibility of the tip of a guide wire is that of cutting axially spaced grooves in and near the tip, with the depths of the grooves increasing toward the tip. See U.S. Pat. No. 5,437,288. The use of cuts to increase flexibility on one side only of a tubular guide wire is disclosed in U.S. Pat. No. 5,411,483.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the invention to provide an improved catheter guide wire apparatus.  
           [0008]    It is also an object of the invention to provide such apparatus which exhibits both torsional stiffness, bending flexibility, and longitudinal strength.  
           [0009]    It is a further object of the invention to provide such apparatus which is simple in design and construction.  
           [0010]    It is another object of the invention, in accordance with one aspect thereof, to provide a catheter guide wire apparatus with improved flow directability characteristics.  
           [0011]    The above and other objects of the invention are realized in a specific illustrative embodiment of a hybrid catheter guide wire apparatus formed of a thin elongate solid body of material which tapers or is otherwise reduced in diameter to a thinner distal termination, and a thin elongate tubular body of material disposed co-linearly to the distal end of the solid body to circumscribe at least a portion thereof. The tubular body, which is constructed to have greater lateral flexibility than the solid body, while retaining torsional stiffness, is attached at its proximal end to the solid body, or at its distal end to the solid body, or at both ends to the solid body. Cuts may be formed in the tubular body, transversely thereof to give the guide wire flexibility without significantly reducing torsional stiffness or strength. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The above and other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description presented in connection with the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 shows a side, fragmented, partially cross-sectional view of one embodiment of a catheter guide wire apparatus made in accordance with the principles of the present invention; and  
         [0014]    [0014]FIGS. 2A and 2B show respectively a side, fragmented, partially cross-sectional view, and an end cross-sectional view taken along lines B-B, of another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    [0015]FIG. 1 shows a side, fragmented, partially cross-sectional, view of one embodiment of a hybrid guide wire  200  made in accordance with the present invention. A pin vise type torquing chuck  206  is shown attached to a proximal end  204  in the usual manner. The guide wire  200  also includes a distal end  208  which tapers (but could be reduced more abruptly) to a thin, narrow section  212 . Mounted over the thin, narrow section  212  is a tubular section  216  whose proximal end  218  abuts the sloping portion  222  of the distal end  208  of the proximal guide wire segment, and whose distal end  226  is rounded to reduce the chance of damage and trauma to the vasculature when the guide wire is being threaded therein.  
         [0016]    Advantageously, the guide wire  200  is constructed of stainless steel and the tubular section  216  is constructed of nickel-titanium alloy to provide for greater lateral flexibility. Additional lateral flexibility can be achieved by providing cuts, slots, gaps or openings  230  along at least a portion of the exterior surface of the tubular section  216 . These cuts may be formed by saw cutting (e.g., diamond grit embedded semiconductor dicing blade), etching (for example using the etching process described in U.S. Pat. No. 5,106,455), laser cutting, or electron discharge machining. Provision of the cuts in the tubular section increases lateral flexibility in the guide wire, while maintaining torsional stiffness.  
         [0017]    The thin, narrow section  212  of the guide wire  200  is shown in the drawing as being an extension of the larger part of the body and thus made of the same material, the section  212  could also be made of a carbon fiber or polymer strand, attached to the larger part of the body  200  (for example, by a suitable adhesive), and this would provide excellent longitudinal strength with very little lateral stiffness. Advantageously, the diameter of the larger proximal part of the catheter guide wire  200  could be from about 0.008 to 0.038 inches, as could be the outside diameter of the tubular section  216 . A preferred diameter is 0.014 inches, with the interior diameter of the hollow of the tubular section  216  being about 0.0085 inches. Of course, the outside diameter of the tubular section  216  could be greater or less than that of the larger part of the catheter guide wire  200 .  
         [0018]    The distal end of the tubular section  216  may be preshaped with a curve to allow for directing the guide wire around curves and bends. Also formed on the distal end  226  of the tubular section  216  is a radiopaque or MRI sensitive marker or band  234 . The band  234  may be gold or platinum alloy (for X-ray fluoroscopy) or gadolinium or dysprosium, or compounds thereof (for MRI) and may be formed on the distal end  226  by deposition, wrapping or use of shape memory alloy (NiTi) effect to “lock” the band around the end. Alternatively, a radiopaque or MRI sensitive plug  238  could be disposed in the distal end  226  of the tubular section  216  and attached to the distal end of the thin, narrow section  212  of the solid body portion of the guide wire  200  (or to the carbon fiber or polymer strand) to both serve as a marker and to assist in holding the tubular section  216  in place over the thin, narrow section  212 . Glue or other adhesives could also be used to hold the tubular section  216  in place, including radiopaque glue. Finally, a radiopaque or MRI sensitive coil or flexible plastic tube could be disposed about the narrow section  212  of the guide wire, within the tubular section  216 , to provide a much larger, more readily viewable marker.  
         [0019]    To improve slidability of the guide wire  200  in a vasculature passageway, the exterior surface of the guide wire, including tubular section  216 , could be sandblasted, beadblasted, sodium bicarbonate-blasted, electropolished and/or coated with a lubricious coating such as a silicon based oil and/or polymer or a hydrophilic polymer. Alternatively, a sleeve could be disposed over the entire length of the guide wire where the sleeve could also be made of a lubricious, hydrophilic polymer, or other polymer and then coated.  
         [0020]    Cuts  230  of various shapes may be selectively spaced along and about the tubular section  216  to provide for selective bending of the tubular section, while maintaining good torsional stiffness. For example, the cuts could be formed at circumferentially-spaced locations about the tubular section  216  and could be formed with various shapes, the depth and thickness of which could be chosen to again allow for preferential bending of the section.  
         [0021]    In the embodiment of FIG. 1, the guide wire  200  can be made “flow directable” by providing a highly flexible distal end. “Flow directability” means that the distal end of the guide wire tends to “flow” with the blood around curves and bends in a vasculature passageway.  
         [0022]    [0022]FIGS. 2A and 2B show respectively a side, fragmented, partially cross-sectional view and an end cross-sectional view of another embodiment of the hybrid catheter guide wire apparatus of the present invention. There shown is a guide wire  300  which tapers (but may be abruptly reduced) at its distal end to a thin, narrow section  304 . A tubular section  308  is mounted about the thin, narrow section  304 , as with the FIG. 1 embodiment, so that its proximal end  312  abuts the sloping portion  316  (or other portion) of the distal end of the guide wire  300 , and its distal end  320  is generally contiguous with the termination of the thin, narrow section  304 . Disposed about the termination of the thin, narrow section  304  and within the distal end  320  of the tubular section  308  is a platinum, radiopaque coil  324 . The coil  324  is held in place to the termination of the thin, narrow section  304  and the distal end  320  of the tubular section  308  by a suitable adhesive.  
         [0023]    Another coil  328  is disposed about the sloping portion  316  of the guide wire  300  near the proximal end  312  of the tubular section  308 , to serve as a spacer or bushing between the tubular section  308  and the guide wire  300 . Advantageously, the coil  328  is made of platinum. The coil  328  is held in place by a suitable adhesive. Thus, the tubular section  308  is held in place about the thin, narrow section  304  by adhesive both at the proximal end  312  and the distal end  320 .  
         [0024]    The coil  324  could be extended rearwardly, or the coil  328  could be extended forwardly, to loosely fill the space between the narrow section  304  and tubular section  308  and thus provide greater viewability of the radiopaque marker. Alternatively, an MRI sensitive or radiopaque flexible tube could be disposed in the space.  
         [0025]    As with the FIG. 1 embodiment, the guide wire  300  advantageously is constructed of stainless steel while the tubular section  308  is constructed of nickel-titanium alloy. Cuts, slots, gaps or openings  332  may be formed along at least a portion of the exterior surface of the tubular section  308  to achieve additional desired lateral flexibility.  
         [0026]    The dimensions of the embodiment of FIGS. 2A and 2B may be similar to those of the FIG. 1 embodiment. A typical length of the tubular section  308  is from 8 to 20 centimeters. Additionally, the distal end of the tubular section  308  may be preshaped with a curve to allow for directing the guide wire around curves and bends, and may be formed to include MRI sensitive markers or bands (in addition to the radiopaque coils  324  and  328 ), as with the FIG. 1 embodiment.  
         [0027]    It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims are intended to cover such modifications and arrangements.