Patent Application
20070293791
Typically, the first tapered segment is about 3 cm in length and the second tapered segment is about 4 cm in length. In a presently preferred embodiment, the guidewire 10 has a proximal core section 12 of about 0.014 inch (0.36 mm) in diameter, the first tapered core segment has a diameter ranging from 0.014 inch down to about 0.008 inch (0.36-0.20 mm) and the second tapered core segment has a diameter ranging from about 0.008 to about 0.002 inch (0.20-0.05 mm). A flattened distal tip 18 extends from the distal end of the second tapered core segment 16 to the body of solder 20 which secures the distal tip 18 of the core member 11 to the distal end of the helical coil 14. A body of solder 21 secures the proximal end of the helical coil 14 to an intermediate location on the second tapered segment 16.
The core member 11 is coated with a multilayer lubricious coating 19 (
The core member may be formed of stainless steel, NiTi alloys or combinations thereof such as described in U.S. Pat. No. 5,341,818 (Abrams et al) which has been incorporated herein. Other materials such as the high strength alloys described in U.S. Pat. No. 5,636,641 (Fariabi), which has also been incorporated herein by reference, may also be used.
The helical coil 14 is formed of a suitable radiopaque material such as platinum or alloys thereof or formed of other material such as stainless steel and coated with a radiopaque material such as gold. The wire from which the coil is made generally has a transverse diameter of about 0.003 inch (0.05 mm). The overall length of the coil 14 is typically about 3 cm. Multiple turns of the distal portion of coil 14 may be expanded to provide additional flexibility.
In an alternative embodiment shown in
While the specific embodiments described above are directed to tapered segments with constant tapers along their lengths, the taper need not be constant. For example, the tapers of contiguous core segments may be gradually increasing in the distal direction, with the taper, i.e. a tangent line, crossing the junction between the two adjacent tapers being a continuous function. Guidewires are generally about 90 to about 300 cm in length, and most commercially available guidewires for the coronary anatomy are either 175 cm or 190 cm in length.
Multiple tapers may be ground simultaneously or as separate operations. A centerless grinder with profile capabilities may be used to grind the tapers simultaneously. A manual centerless grinding may be employed to create separate tapers in separate operations. Tapers may also be formed by other means such as chemical means.
Considering now the lubricious coating 19 (
In one embodiment, a hydrophobic, silicone-based coating 19b (
It is noted that the dual silicone formulations 19b and 19c may, alternatively, be mixed together prior to application. In that case, the components of the two formulations are applied as a single coat 19b that has advantages of both formulations. An additional coat of the mixed formulation may be applied as layer 19c or, alternatively, a single coat 19b atop the TEFLON® base coat may be sufficient.
In another approach, the silicone coating may be applied directly to the bare metal guide wire, which may optionally be pretreated to change its color. This direct-application approach takes advantage of the excellent adhesion of certain silicones to polar substrates such as bare steel. Furthermore, this eliminates the PTFE or polymer base coat process, thus making the wire easier and less costly to manufacture. Another advantage of this approach is that the overall diameter of the proximal section of the guide wire is now lessened by what would have been the thickness of the PTFE or polymer base-coat, allowing the guide wire to fit more easily into smaller diameter catheters.
As another variation, the silicone top coating or coatings may be applied to a base coat composed of a polymer or resin that has better silicone wetting and bonding characteristics as compared to TEFLON®. Examples include HDPE, surface treated HDPE or variations thereof.
In another embodiment in which the proximal portion of the guide wire is coated with a silicone-based coating, a preferred coating consists of amino functional dimethylsiloxane copolymer (Dow Corning MDX-4-4159 fluid, for example) and/or polydimethylsiloxane liquid (Dow 360, for example). The coating can range from 1-50% active silicone; however, the preferred embodiment would consist of a coating that is 2-10% active silicone. Substrates for the silicone-based coating could be, as alternatives to TEFLON®, various fluoropolymers, polyethylene, polypropylene, stainless steel, or nickel titanium alloys.
The coating is typically applied to the guidewire by dipping, wiping, spraying or any other method of application known in the art. The coating is oftentimes cured at room temperature, or may be heated (by, for example, blown heated air) to accelerate the cure. Optionally, the guidewire can be heated before applying the coating to help improve adhesion.
In another embodiment, the TEFLON®-coated proximal section is further coated with one or more additional layers of a release agent or compound The release layer, which can alternatively be called a “top” layer, can be from any of a number of release agent groups including, but not limited to, spray PTFE, paraffins, olefins, and fats.
In another embodiment, the proximal portion of the guide wire is coated with a polydimethylsiloxane liquid (Dow 360, for example). The coating can range in viscosity from 10 cs to 50,000 cs. However, the preferred embodiment would consist of a liquid with a viscosity of 100 cs to 1000 cs. Substrates for the polydimethylsiloxane coating could be fluoropolymers (including but not limited to polytetrafluoroethylene), polyethylene, polypropylene, stainless steel, or nickel titanium alloys. That is, the coating may be applied upon a TEFLON® base coat or, alternatively, upon another base coat or even upon bare metal.
In another embodiment, the silicone wax coating on the proximal portion of the guide wire is intended to provide performance benefits with regards to interaction between the catheter inner lumen and the guide wire because the silicone surface is resistant to the adhesion of blood and contrast.
The proximal portion of the guide wire is coated with a silicone wax coating. The coating consists of silicone wax with viscosities of 50,000 cP to 1,000,000 cP, with 75,000 cP to 100,000 cP being the preferred viscosity. Substrates for the silicone wax coating could be fluoropolymers (including but not limited to polyetrafluoroethylene), polyethylene, polypropylene, stainless steel, or nickel titanium alloys. The wire can be heated before applying the coating to help improve adhesion. The coating is applied to the wire with a wiping process. Heating the coating may allow for dip or spray processing.
The approach described thus far is not limited to a particular guidewire structure. The general principle in this approach is to make the proximal portion of the guidewire particularly lubricious, irrespective of the particular guidewire structure. The advantages of this approach can extend to a broad range of guidewire designs.
For example,
Also shown in
Considering further
In this commercial family of guidewires, the distal portion of the wire is coated with a hydrocoat hydrophilic coating for, among other things, smooth lesion access. Tip and intermediate coils in the distal portion provide excellent tracking and tactile feedback. A transitionless parabolic core grind, as opposed to a conventional tapered core, eliminates prolapse points to provide easy tracking and conserves diameter to provide excellent torque response.
Generally, the HI-TORQUE ADVANCE™ family of guidewires are intended to facilitate the placement of interventional percutaneous transluminal coronary angioplasty (PTCA) and percutaneous transluminal angioplasty (PTA) catheters and other interventional devices including: intravascular stents, intravascular ultrasound devices and intravascular drug eluting stents.
As a matter of terminology, the “proximal” portion of the guidewire is typically the lengthy segment wherein there is not a reduction in the diameter of the core of the wire. In contrast, the “distal” portion often extends from the tip of the wire for about 25-30 centimeters. During use, the “distal” portion travels outside of the guiding catheter and into the targeted portion of the anatomy, coming into contact with the arterial wall. While the “distal” portion is a minor length of the guidewire beginning at the tip, the “proximal” portion is the major part of the wire. As a non-limiting example, the “proximal” portion may extend for 160-270 centimeters in some guidewires.
As another matter of terminology, it is noted that in most preferred embodiments, the proximal portion is continuously coated with the lubricious coating except, in some embodiments, in areas that are specially designated as a radio-opaque marker. In this sense, “continuously coated” is meant to include instances in which the entire proximal portion is coated with the coating, and instances in which the entire proximal portion is coated except for radio-opaque markers. In other embodiments, however, the proximal portion may be pattern coated, with the lubricious coating applied in any pattern suitable for use in the body.
The term “TEFLON®” as used herein means polytetrafluoroethylene, or closely-related materials, such as fluorinated ethylene-propylene (FEP), perfluoroalkoxy polymer resin (PFA) and the like.
While particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.
