Abstract:
A coated wire for medical applications including a length of biocompatible wire material. The wire material can be coated along a portion of the perimeter of the wire. The deposition of the coating can cover less than the total circumference of the wire.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/189,921, filed on Mar. 16, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the medical field of intraluminal wires used to access distal areas of the body. Specifically, the present invention relates to wires partially coated with a lubricious material. The coated wire may be used to construct a guide wire with a central core and surrounded by the coated wire coiled around the core. Alternatively, the partially coated wire may be used to construct a variety of devices including baskets, snares, laparoscopic instruments or small coils that may be used within numerous medical specialties, including cardiology, urology, and radiology. 
     BACKGROUND OF THE INVENTION 
     Minimally invasive medical procedures can be performed at remote sites by inserting and navigating endoscopic equipment into and through blood vessels or body lumens to the treatment site. A specific site may be difficult to reach for many reasons including vessel or tract tortuosity, lumen constriction e.g. edema or tumor impingement or lumen blockage e.g. ureterolithiasis. 
     Insertion of a guide wire can facilitate access to the treatment site. Catheters or medical tools can then be advanced over the guide wire to the specific site. To achieve accurate placement the guide wire should incorporate the somewhat competing features of pushability, kink resistance, torqueability and bendability. Guide wire designs known in the art to meet these criteria include a guide wire design characterized by a solid metal core surrounded by a metal coil. Metals for the core may include spring steels, stainless steels and NiTi alloys. The same variety of metals used as core materials can be used for the coil wire, including stainless steel or NiTi alloys such as NITINOL wire. The coil wire may be round wire or flat wire; the coil wire may be made of a single wire strand or may be made of multifilar wire. The coil wire may wrap around the entire length of the core or only a portion of the core. The adjacent turns of the coil wire may or may not be tightly wrapped with succeeding turns of the coil wire touching, the coil wire may be wrapped around the core in an open fashion, or the core may be surrounded by coil wire that is tightly wrapped along a portion of the core and open wrapped along a subsequent portion of the core. The coil can be, but need not be, in axial compression. 
     Important to smooth advancement and retraction of the guide wire is an exterior surface of the guide wire that creates minimal friction between the inner wall of the vasculature or body lumen and the exterior surface of the guide wire. Similarly, to advance catheters or other equipment over or along a guide wire, a balance is required between ease of movement of the catheter or equipment along the guide wire and retention of the desired positioning of the guide wire at the treatment site. 
     Guide wire construction typically includes use of a pre-coated coil wire to minimize friction between the external surface of the guide wire and the inner wall of the bodily lumen or medical equipment. The guide wire could, however, be spray coated after assembly to increase lubricity. 
     Circumferential coating of the wire coil may interfere with or prevent desired bonding (including adhesive, weld, and solder) between the coil wire and core. Abrasion between adjacent coated coils of the coil wire may result in flaking or sloughing of coating material. Abraded particles of coating material could enter the vascular or body lumen. 
     Construction and use requirements of various other coated medical wires and endoscopic instruments, such as urology baskets and snares, laparoscopic instruments or radiology coils may mimic the construction and use requirements of a coated guide wire. 
     SUMMARY OF THE INVENTION 
     The invention pertains to a wire partially coated with a lubricious material. The present invention provides benefits over the prior art by providing a wire that is coated only along a portion of the wire perimeter. The lubricious coating is deposited on the wire along the exterior perimeter portion of the wire that could have direct contact with either an internal body lumen or an inner lumen of a catheter. Lubricious materials for coating select portions of the wire include PTFE and hydrophilic materials such as HYDROPASS or GLIDEX. A single material may be coated along the selected portion of the wire, or different materials may be applied along different segments of the wire. 
     The uncoated portions of the wire provide surfaces for bonding to other materials that are preferably free of interference from the coating material. For example, guide wire construction may require bonding between a wire core and wire coil surrounding the core. The uncoated portions of the coil wire provide a surface preferably free from a coating material; such uncoated portion may more readily enhance bonding between the core and the coil wire. 
     If the partially coated wire is formed into a coil configuration, such as may occur in construction of a guide wire, where interstices of the coils are preferably uncoated, the potential for coating material flake-off or rub-off resulting from abrasion between adjacent turns of the coiled wire is reduced or eliminated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal section of an embodiment of a guide wire assembly consisting of a wire core surrounded by a coated coil wire; 
     FIG. 2 is a longitudinal section of a guide wire assembly depicting the wire core wrapped by a coil wire in both an open fashion and a tightly wrapped manner; 
     FIG. 3 is a longitudinal section of a guide wire assembly depicting the wire core tightly wrapped by the coil wire; 
     FIG. 4 is a cross section of a partially coated round coil wire; 
     FIG. 5 is a cross section of a partially coated flat coil wire; 
     FIG. 6 is an expanded view of a portion of a longitudinal section of a guide wire assembly consisting of a wire core surrounded by a coated coil wire; 
     FIG. 7 is a representation of the winding of a coil wire around the core wire; 
     FIG. 8 is a longitudinal section of a guide wire assembly in which the coil wire is bonded with adhesive to the core wire; and 
     FIG. 9 depicts use of two different lubricious coatings to pre-coat the coil wire. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description references the drawings in which like elements in different drawings are identically numbered. The drawings depict selected embodiments and are not intended to limit the scope of the invention. 
     FIG. 1 shows an embodiment of the guide wire  10 . The dimensions of the guide wire  10  and the core  20  will vary depending on the medical application. The distal portion  22  of core  20  may be tapered, as shown, to provide flexibility to guide wire  10 . 
     Core  20  may be formed of spring steels, stainless steel, super-elastic materials such as the NiTi alloys e.g. NITINOL, linear-elastic materials or other biocompatible materials. 
     Surrounding core  20  is coil wire  30 . Coil wire over wire core is well known in the guide wire art and is described in detail in U.S. Pat. No. 5,147,317 to Shank which is incorporated by reference. Coil wire  40  may be made of a variety of metallic materials including super-elastic or linear-elastic materials such as NiTi alloy or NITINOL, conventional stainless steel alloys such as 304V, or 361L. 
     Coil wire  30  is wrapped around some portion of the length of core  20 . In one embodiment, as depicted in FIG. 1, the coil wire is wrapped around a central portion of the core; the proximal portion  22  and tapered distal portion  24  of the core may be surrounded by polymer tips,  23  and  25  respectively. 
     Coil wire  30  may be formed of round wire as depicted in cross-section in FIG. 4 or formed of flat ribbon wire as depicted in cross-section in FIG.  5 . The flat ribbon wire can be formed by, for example, rolling a round cross sectional wire. The transverse ends of the cross section of the ribbon wire can be rounded or with subsequent processing squared. It can be appreciated that numerous cross sectional shapes can be used in accordance with the present invention. Or, coil  30  may be formed of cross-wound multifilar (as described in U.S. Pat. No. 4,932,419 to de Toledo which is incorporated herein by reference) or multifilar single coil wire. 
     Coil wire  30  is wrapped in a helical fashion about core  20 . The pitch chosen to wind the coil wire  30  may be determined by the particular application and flexibility requirements for the guide wire  10 . 
     The pitch can vary from tightly wrapped so that each turn touches the preceding turn or the pitch may be such that coil wire  30  is wrapped about core  20  in an open fashion so that there is space between each succeeding turn of the coil wire. 
     FIG. 2 demonstrates an open fashion of wrapping the coil wire  30 . Succeeding wraps  35  of coil wire  30  do not overlap or touch the preceding wrap. 
     FIG.  2  and FIG. 3 demonstrate sections of coil  30  which are tightly wrapped so that succeeding turns  38  of coil wire  30  touch preceding turns  38  of coil wire  30 . As depicted in FIG. 2, in one embodiment the pitch of coil wire  30  varies along the distance of core wire  20 , providing variable flexibility along the length of guide wire  10 . 
     FIGS. 4 and 5 illustrate, in cross section of a round coil wire  30 A, and a flat coil wire  30 B, application of a lubricious coating  40  along an exterior portion  35  of the perimeter of the coil wire  30 A or  30 B. The remaining portion  32  of the perimeter of the coil wire is preferably uncoated. Lubricious materials for coating the coil wire  30  can include hydrophobic materials such as PTFE and silicon, and hydrophilic materials such as HYDROPASS. 
     Methods for selectively coating the coil wire  30  include masking wire segment  32  prior to application of the coating material  40  along the wire segment  35  selected for coating. Alternatively, the coating material  40  may be applied onto the select segment  35  by dipping a portion of the wire into the coating material or by spraying the coating material onto selected portions of the wire. Other methods for selectively coating a wire include rolling the material onto the wire. Transfer methods in the coating and printing arts may also be used to selectively coat the wire. 
     The longitudinal section of the guide wire  20  shows in FIG. 6 the outer disposition  40  of the coating on the coil wire  30 . The coil wire  30  interface  32  with the core wire  20  is preferably free of lubricious coating. 
     An exploded longitudinal view of an open wrapped coil wire in FIG. 7 shows the application of the coating  40  along the external surface of coil wire  30 ; edges  32  and the lower surface of coil wire  30  are preferably uncoated. Abrasion from surface-to-surface interface between consecutive turns of coil wire  30  are unlikely to result in chipping or flaking the coating  40  since these interfaces are preferably free of any coating. 
     Bonding core wire  20  to coil wire  30  may provide improved torque transmission of guide wire  10 . Coil wire  30  may be bonded to core wire  20  along the length of core wire  20  or in discrete sections. Adhesive bonding, swaging, brazing, soldering or welding are among the alternatives to bond the coil wire  30  to the core wire  20 . Plating or etching is usually not required to prepare the core wire  20  surface since the coil wire bonding surface  32  is preferably uncoated. Alternately, specialty platings may be applied to enhance adhesion of the coating to the wire, or enhanced biocompatibility of the uncoated surface in the presence of body fluids. This is especially advantageous when the core wire  20  and coil wire  30  are materials that are difficult to weld together; adhesive bonding  50  offers a potential solution. FIG. 8 shows adhesive bonds  50  in areas that could previously have required spot welds or ball welds. 
     An alternative guide wire  10  construction includes the use of different lubricious coatings along the surface of the coil wire  30 . In one alternative, the proximal segment of the core wire  20  may be wound with Teflon coated  46  coil wire  30 ; the distal segment of the core wire  20  may be wound with a hydrophilic material such as HYDROPASS coated  48  coil wire  30 . 
     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 invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.