Guide wire with stranded tip

ES 2 339 114 T3

DESCRIPTION

Guide wire with a twisted wire end.

The present invention relates to a guide wire for use in surgical procedures. In particular, the present invention relates to a guidewire with a distal tip provided with multiple wires. Said type of guide wires is described by way of example in WO-A-92/13483.

Background of the present invention

Generally, guide wires are elongated structures used in medical procedures. In such procedures, a distal portion of the wire is placed inside a lumen of a patient's body in order to acquire and / or maintain access to the area of ​​interest. For example, an area of ​​interest on a patient's body may be a lumen with a local narrowing at a certain point in the patient's vascular system. A catheter can be advanced along a guidewire for treatment or diagnosis.

A surgeon, for example a medical doctor, is responsible for introducing the guide wire and catheter into the patient's body. A proximal part of the wire and a proximal part of the catheter protrude outside the patient's body so that they can be manipulated by the surgeon. The surgeon guides the guide wire directing it to a treatment area by forming a slight curve at the distal end of the wire, introducing the wire through the skin into the patient's body, advancing it and making twisting movements until reaching the area of interest. The guidewire can be directed into a channel offset from the axis by twisting the wire until the curved tip enters the channel and then advancing the guidewire along the channel. In the case of systems along the wire, it is necessary that at least a portion of the wire extends relative to the proximal end of the catheter, thus allowing the catheter to be manipulated axially with respect to the wire.

It is possible to deliberately hold the guidewire in an axial position within the lumen of the patient's body, in order to allow access to a treatment or diagnostic site. The wire can be positioned by any means that allows the relative position of the wire within the lumen to be determined, for example by a securely attached distal guard, or by manually maintaining the position of the wire within the lumen. Once an axial position has been established, the wire remains in position, so that devices such as a balloon catheter, a stent, a distal protection device, an atherectomy catheter, a thrombectomy catheter, or the like , can advance along the wire to the point of treatment or diagnosis.

Guide wires are shown to have a number of key requirements for their use. They need to be flexible to track well in a sinuous anatomy. In particular, flexibility and movement control is intended at the distal end of a guidewire Preferably, the guidewire has isotropic bending characteristics along the proximal shaft to prevent vibrations when movements are made. torsion. Also, the guidewire must have good structural integrity so that it does not inadvertently bend, warp, or pull apart under tension. The guide wires must have good torsional stiffness over their entire length, so that they can be directed towards an area of ​​interest by applying torsional movements. At least a portion of the guidewire must be radiopaque so that it can be visualized using the fluoroscope during an intervention.

Guide wires often comprise a "flexible tip" at their distal end. Such a flexible distal tip provides a non-traumatic and radiopaque finish and can be of any length. A non-traumatic tip prevents damage to the vessels during initial insertion or subsequent advancement of the guidewire. A radiopaque tip is helpful for the clinician to verify that the tip has been inserted correctly during fluoroscopy. The flexible tip can comprise a flexible or elastic material, such as a metal (eg stainless steel, iron alloys such as Elgiloy ™, or shape memory metals such as nickel titanium alloys) or polymers (eg polyetheretherketone. (PEEK), polyimide, polyester, PEBAX, urethane, polytetrafluoroethylene (PTFE), and the like). Flexible materials are preferred as they tend to preserve their shape. Initially, the clinician shapes the tip, usually with a slight bend, and then, as the wire advances through the body, the tip deflects when it encounters obstacles. It is convenient, after the inevitable deviations that occur during insertion, that the tip recovers its pre-established shape.

The transition between a guidewire and its distal tip should preferably be smooth and continuous, in order to enhance its pushability and trajectory following. Various types of distal tips comprising radiopaque coils and coatings are used in prior art guide wires. Typically, the coil tips are directly or indirectly attached or welded to the distal end of the guidewire, with the consequence of forming rigid zones that affect the flexibility and manipulability of the guidewire. An additional drawback is that the coils they require direct or indirect welding or adhesive bonding procedures, which can have adverse effects on fluoroscope monitoring. Also, radiopaque coated tips can cause unintended stiffness of the distal end of a guidewire.In addition, conventional guidewire coils are not robust in tension, so it is not unusual for the tip to separate during use. Guide Wire Gap Often times

ES 2 339 114 T3 tip involves elongation and unwinding of the coil which offers minimal resistance to tensile forces, due to the fact that the turns are essentially transverse to the axis of the coil. Although security wires are often added to the tip of the guidewire to prevent elongation of the coil, these wires need to have a small cross section to prevent the tip of the guidewire from being even stiffer. Cross section must be small, the strength of the security threads is limited.

In this state of the art, guide wires are required that in particular can advance easily, are easy to control and are flexible throughout their length, being sufficiently robust against stress in order to prevent deterioration during use. In particular, it would be desirable to have a more flexible and torsional distal end of the guidewire.

Summary of the present invention

The present invention provides a guidewire comprising an elongated flexible core with a proximal area, a proximal end, a distal area, and a distal end, the distal area having a pointed end; a plurality of twisted wires helically wound parallel to each other and arranged on at least part of said distal area with a pointed end of the web; a polymeric tie layer disposed on at least a portion of the plurality of braided yarns; and a polymeric layer with lubricating power disposed on the polymeric tie layer.

Also, the present invention provides a guidewire comprising an elongated flexible core with a proximal area, a proximal end, a distal area, and a distal end, the distal area having a pointed end; a plurality of twisted wires helically wound parallel to each other and arranged on at least part of said distal area with a pointed end of the web; and a polymeric tie layer disposed over at least part of the plurality of braided yarns. The polymeric tie layer provides the only form of bond between the plurality of braided yarns and the core.

It should be understood that both the foregoing general description and the following detailed description are given by way of example and explanation, and are intended to provide further explanation of the claims of the present invention.

Brief description of the drawings

A cross-sectional view of an embodiment of the guide wire according to the present invention is shown in Figure 1A.

Figure 1B shows a cross-sectional side view of the embodiment of Figure 1A.

Figures 1C to 1J show additional embodiments of the distal portion of the central core of the guidewire.

Figure 2 shows a cross-sectional view of another embodiment of the guide wire according to the present invention.

Figures 3A to 3D show cross-sectional views of other embodiments of the guidewire according to the present invention.

Figure 4 shows a cross-sectional view of another embodiment of the guide wire according to the present invention.

Side views of the distal ends of various embodiments of guidewire according to the present invention are depicted in Figures 5A to 5C.

Figure 6 shows a side view of another embodiment of the guide wire according to the present invention.

Figure 7 shows a perspective view of a section of the core with braided wires arranged around it.

Figure 8 shows a side view of a section of wires with twisted strands.

Detailed description of the preferred embodiments

In this context, the terms "distal" and "proximal" refer to the relative position of the guidewire in a lumen. The most "proximal" point of the guidewire is the end of the guidewire that extends outside the body and is closest to the physician. The most "distal" point of the guidewire is the end of the guidewire furthest away, which has entered a body lumen through the entry zone.

ES 2 339 114 T3

The aim of the guide wire according to the present invention is its use in surgical interventions, in diagnostics and to access an area, for example in the case of coronary, peripheral, neurovascular or gastrointestinal applications.

The guide wire according to the present invention may comprise a core, braided filaments or wires of various materials arranged on the core to obtain flexibility and workability, a polymeric coating arranged on the braided wires and a lubricity coating arranged on at least the distal portion of the guidewire In one embodiment, the distal tip also comprises polymers containing radiopaque material.

Suitable guidewire materials include metals, either one or more, polymers or shape memory metal alloys, stainless steel, and engineered polymers. Such materials include titanium and its alloys, cobalt-chromium-nickel-molybdenum-iron alloys (commercially available under the brand name Elgiloy^TM), and polymers, for example liquid crystal polymers, polyetheretherketone (PEEK), polyimide and polyester. In particular, superelastic shape memory metals or polymers are disclosed to be suitable for applications where guidewire is intended to maintain a predetermined curvature. A superelastic or shape memory metal comprising nickel and titanium, known as “nitinol” is commercially available in various sizes, can be hot molded, can be compressed for access to a point and then released so that it returns to the hot modeled shape.

The core is shaped by any suitable means, usually by grinding or by corrosion, until the desired shape and dimension is obtained. For example, a certain intended length of the distal portion of the web is made narrower and / or flatter than the proximal portion of the web. Grinding is one of the preferred methods of reducing the outside diameter of the web. It should be noted that the core can be provided with a coating of lubricating power, for example polytetrafluoroethylene (PTFE) or another type of fluorinated polymer, parylene, polyurethanes or silicones. The core can be coated before or after grinding.

One or more braided wires of a shape memory alloy or a combination of materials designed to impart flexibility to the distal tip are arranged at the distal portion of the web. Such materials include titanium and its alloys, cobalt-chromium-nickel-molybdenum-iron alloys (commercially available under the brand name Elgiloy^TM), stainless steel, tungsten, platinum and engineered polymers, for example liquid crystal polymers, polyetheretherketone (PEEK), polyimide and polyester. It is possible to place said braided threads in the vicinity of the core or adjacent to it. In preferred embodiments, 3 to 24 filaments or yarns, with diameters ranging from 0.0025 cm (0.001 inch) to about 0.025 cm (0.010 inch), are arranged next to the web.

An optional polymeric coating or layer comprises one or more polymers, for example block copolymers of polyamide (commercially available under the trademark "PEBAX"), nylon, ethyl vinyl acetate, silicone, urethane, polytetrafluoroethylene or polyethylene. The polymeric coating can be made by immersion or by direct extrusion. The polymeric liner can be comprised of a one-piece hot shrink tubing that coats the core by applying heat to the tubing. The polymeric coating can be made by arranging part of the thermoplastic tube in a part of the interior of the hot shrink tube at the tip of the wire and by heat reflux of the thermoplastic tube. To do this, apply enough heat to melt the thermoplastic tube and simultaneously recover the hot shrink hose, so that the pressure applied by the hot shrink hose forces contact of the molten thermoplastic tube with the non-melted components. from the tip.

A good bond between elements can often be achieved using this technique. Once the polymeric coating has been applied, an additional grinding operation may have to be required to obtain a consistent outer diameter along the entire length of the polymeric coating.

Preferably, an optional lubricity coating is provided on the braided yarns, on the polymeric layer, if present, or on both. Usually, the proximal part of the web is already coated with a layer of lubricating power and no additional coating is necessary. Suitable lubricity coatings include hydrophilic materials, eg, povidone (PVP), polyethylene oxide, polyethylene glycol, cellulose polymers, and hydrophilic maleic anhydride or hydrophobic materials, eg, silicone, PTFE or FEP.

Typically such coatings are applied by dipping or spraying, and hot setting procedures can be employed. For example, curing temperatures of up to about 70 ° C are used for silicone coatings, and for PTFE coatings it may be necessary to obtain temperatures of several hundred degrees.

In addition to the lubricity coating, bioactive coatings can be applied everywhere or partially on the guidewire. Said type of coatings may also incorporate other materials such as heparin, hirudin and the like, or other drugs. Typically, such type of dip coatings are applied. Bioactive coatings are ideal for preventing blood clots or for delivering drugs to a specific site.

ES 2 339 114 T3

Additionally, part of the tip can comprise a flexible polymer such as PEBAX, polyurethane, or polyethylene that includes radiopaque material. Said type of radiopaque materials are well known in the state of the art and usually comprise elements of tungsten, barium and / or bismuth.

The figures do not represent the total length of the guide wire, and it should be understood that the length of said cable can vary at will, although it usually comprises between 30 and 400 cm. Some procedures, such as the introduction of a peripherally inserted central catheter (PICC), or vascular access, may require guidewires of lengths between 30 and 80 cm. Typically, the lengths of the guide wires used in coronary, peripheral, and neurovascular procedures are between 170 and 300 cm. With such lengths, standardized quick-change systems and catheter systems can be used along the wire, respectively. Also, the length of the shaped distal end can vary, for example, between 5 and 80 cm.

The outer diameter of the guidewire ranges from about 0.013 cm (0.005 inches) to about 0.097 cm (0.038 inches). These diameters are standard for guidewires used in neurovascular, cardiovascular, peripheral, and gastrointestinal procedures. Preferably, the diameter is kept relatively constant along the length of the guidewire, although slight taper may occur at the distal end.

In the following, various embodiments according to the present invention will be described with reference to the figure drawings. It should be understood that for the purpose of better describing the present invention, the drawings are not to scale.

In addition, some of the figures include elements that are magnified or distorted in order to show characteristics that would not otherwise be apparent.

Figure 1A illustrates a guidewire 10 comprising a central core 14. In a preferred design, said core 14 is made of nitinol, NiTiCr, or a nitinol alloy with an austenitic finishing temperature below the temperature ambient. The proximal part 11 of the central web 14 has a constant diameter D1, which is reduced to a value D2 in a distal part 13, through the taper zone 12. A typical diameter D1 is 0.044 cm (0.0175 inches), while a typical diameter D2 is 0.0076 cm (0.003 inches), although it is clear that any desired diameter value can be used. The central web 14 extends to the distal tip 13a. The twisted strands of the wire 15 are arranged in the distal part 13 and in the taper zone 12. In one embodiment, 16 nitinol stranded wires of diameter 0.0064 cm (0.0025 inches) are arranged, helically wound obtaining a total diameter of 0.036 cm (0.014 inches), as shown in Figure 7. The helical strands of wire 15 can be attached to the central core 14 by adhesive, direct or indirect welding, crimping a tubular tape over the strands, or the like, at the point where the twisted strands of wire 15 come to a stop. the taper zone 12, or they may remain unattached to the central web 14. The helical wires of wire 15 can be attached to the distal tip 13a by adhesive, direct or indirect welding, crimping of a tubular tape over the wires, or the like, at the point where the twisted wires of wire 15 come to a stop. to the central web 14 or the enlarged distal end of the web (described later) or they may remain unattached to the central web 14. A cross-sectional drawing through the distal portion 13 is shown in Figure 1B. In the example mentioned above, the wire made of helical strands possesses enormous strength, compared to a conventional wire in which the core with a single filament with a diameter of approximately 0.0076 cm (0.003 inch) will be used close to the tip. The cross-sectional area of ​​sixteen 0.0064 cm (0.0025 inch) diameter stranded wires is approximately eleven times the cross-sectional area of ​​a 0.0076 cm (0.003 inch) diameter core.

On the braided threads 15 a polymeric coating 16 is arranged, which covers the threads 15 from the taper zone 12 to the tip 13a, and preferably comprises flexible polymers, for example PEBAX or polyethylene. The polymeric coating is applied so that the external diameter of the distal part is constant, or it can be applied subsequently, for example by grinding, to obtain a diameter similar to that of the proximal part 11. Optionally, the polymeric coating 16 can be applied along the entire length of the guide wire 10, or partially on the guide wire 10, as long as the diameter of the proximal part of the web 11 is reduced to adapt to the thickness. of the polymeric coating 16. In another embodiment, the polymeric coating partially or completely fills the annular space 17 between the central core 14 and the stranded strands of the wire 15.

On the polymeric coating 15 is arranged a layer of lubricating power 18, which covers the most distal 5 to 50 cm of the guide wire Preferably, the layer of lubricating power comprises a hydrophilic coating, which in part comprises maleic anhydride, although said layer is can be made in any of the materials described above.

In another embodiment, the polymeric coating can be totally or partially replaced by a radiopaque metallic coil, in a manner known in the current art.

Figures 1C to 1J illustrate additional embodiments of the distal portion 13 of the central core of guide wire 14. Figure 1C shows a constant diameter portion similar to that of Figure 1A. In figure 1D a part of linear taper is represented. In figure 1E a part of parabolic taper is represented. In the

Figure 1F shows two parts of constant diameter separated by a step. It is understood that any combination of steps, tapers, and parts of constant diameter can be used to configure the distal portion 13. An enlarged distal end is depicted in Figure 1G, which simplifies the manufacturing process by concentrically aligning the core with the braided wires. An elongated distal end can be combined with any of the aforementioned designs with a core extending to or near the distal tip. If the core extends beyond the distal tip, an enlarged area in the wire can be ground near the distal end.

Enlarged areas near the distal end of the wire are described in US Patent No. 5,067,489.

Figure 1H shows a socket 13d arranged in the part of the central web 13c and a part of the distal web 13b with lateral play. Figure 1L shows a part of the central web 13c and a part of the distal web 13b facing each other end to end. Figure 1J shows a part of the central web 13c and a part of the distal web 13b that are superimposed. In Figures 1H to 1J, the part of the distal core can be made of metal or polymer, its stiffness can be adjusted by joining different polymeric segments end-to-end or by varying the composition or characteristics along the length, and it can present a section transversal round, flat, ovoid, or other different. A particularly preferred combination is a stainless steel central core and a nitinol distal core, since the wire has a suitable structure throughout the proximal part and good resistance to deformation and deterioration in the area of ​​the tip. In these socket designs, the outer layer of the threads provides axial strength.

In figure 2 another embodiment of the guide wire according to the present invention is illustrated, in which the guide wire 30 has a proximal part 31 and a distal part 33. Furthermore, the distal part 33 has a first taper zone 43, wherein the diameter of the core of the wire 34 is reduced from a first value D1 to a value D2. The core 34 extends distally to the second taper zone 44, where the diameter D3 of the core of the wire 34 is even smaller. Along said zone 44 and the zone distal but proximal to zone 45, 16 twisted nitinol wires with a diameter of 0.0064 cm (0.0025 inches) are arranged, helically wound to obtain an overall diameter of 0.036 cm ( 0.014 inches), as shown in figure 7. The braided wires are arranged in such a way that by joining the value of the diameter of the core and of said wires in this area, a value slightly smaller than the diameter D1 is obtained. The core of the wire 34 extends distally and ends at the distal end 33a through a third taper zone 45. For this reason, the diameter of the most distal end of the core of the wire has the smallest value D4. Said most distal end, that is to say the area between the taper zone 45 and the distal end 33a, is coated with a polymeric coating 46. The polymeric coating is applied so that the distal end has essentially the same diameter as the adjacent section of the core of the wire, in which the braided wires are arranged. The entire distal area 33, as well as the taper area 43, is covered by a radiopaque polymer 36, obtaining a distal part with a diameter essentially equal to that of the central core, that is, a diameter D1. Finally, a lubricity coating 38 is applied along the distal portion of the guidewire, which is ready for use.

Alternatively, the polymeric coating 46 may partially comprise radiopaque fillers, as is known in the art. Optionally, the radiopaque polymer 36 can be dispensed with and the diameter of the wires 47 and of the polymeric coating 46 can be increased to a value essentially equal to the value of the diameter D1. In another embodiment, the polymeric coating can be replaced, totally or partially, by a radiopaque metallic coil, as is known in the state of the art.

Another embodiment of the guidewire according to the present invention is illustrated in Figure 3A, in which the guidewire 20 has a proximal part 21, a distal part 23 and a taper area 22. The cross section of the part Distal may be flat, round, or it may be non-uniform, as described in connection with Figure 1A. Similar to the embodiment shown in FIG. 1A, the diameter DI of the proximal portion of the central web 24 is greater than the diameter D2 of the distal portion. The central web 24 does not extend to the distal tip 23a, as was the case in the embodiment shown in FIG. 1A, but is truncated near the taper area 22 at a certain distance from the distal tip 23a. Center core 24 is attached in zone 25a to helically wound metal braided wires 25. In one embodiment, sixteen 0.001 inch diameter nitinol braided wires are used, helically wound to form an outside diameter tube. approximately 0.013 cm (0.005 inches). The braided wires are joined by adhesive or direct or indirect welding, or a tubular tape (not shown) can be used to crimp the braided wires to the central core, or other means may be used. For a guide wire of about 300 cm in length, the length of the twisted wires 25 is about 25 cm. Helically wound wires are more robust than a conventional comparable wire, using a single-stranded core of approximately 0.076 cm (0.003 inch) diameter in the vicinity of the distal tip. In the examples mentioned above, the cross section of the single strand core is approximately 55% of that of the braided pattern.

The polymeric coating 26 is applied along the entire length of the guide wire, and consequently throughout the length of said wire a constant diameter is obtained. That is, the diameter of the polymer-coated distal portion is the same as the diameter of the proximal polymer-coated core. The coating can be radiopaque due to the effect of fillers added to the polymer, as described above. Additionally, a layer of lubricating power 28 is applied along the distal portion of the guidewire. In another embodiment, the polymeric coating may be replaced, totally or partially, by a radiopaque metallic coil, as known in the art. state of the art.

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In Figure 3B, for a wire similar to that of Figure 3A, the connection between the core and the braided wires is represented in more detail. A crimp tape 29 is shown, which can be used optionally and which can be made of stainless steel, platinum, platinum / iridium, titanium, or another type of malleable and resistant material. A preferred combination is a stainless steel core and nitinol braided wires. Braided wires 25 arranged end-to-end with the core of the wire 24 are shown in Figure 3C. The polymeric coating provides a certain tensile force. In a preferred embodiment, the wires with braided strands comprise a central polymeric core inside the braided tubular structure, in order to prevent the strands from breaking inside the central tubular zone. Figure 3D shows a core of wire 24 extending to the distal end and stranded wires 25 on said core. This figure is similar to figure 1A, although the twisted wires are not close to the surface of the wire.

In Figure 4 another embodiment of a guidewire according to the present invention is illustrated, in which the guidewire 50 comprises a proximal part 51 and a distal part 53 terminating in a distal tip 53a. The proximal part 51 of the core of the wire 54 has a first diameter D1 and a first taper area 63. The central web tapers in the region 63 in the distal direction until a reduced diameter of the value D2 is obtained, and then tapers again in the region 64 to the flattened end 65 of the central web. Attached to the flattened end 65 are braided nitinol wires 55 provided with a radiopaque coil 56 disposed thereon. In one embodiment, eight twisted wires having a diameter of 0.038 cm (0.0015 inches) are used to form the braided portion. The stranded wires are attached to the flattened end 65 by direct or indirect welding, adhesive bonding, or by means of a hot shrink tubing. With an optional solder 59, the stranded wires 55 can be attached to the coil 56. A radiopaque coil can be arranged around the entire length of the stranded wires 55, or only around a portion. On the distal part 53 and on the conical part 63 a layer of polymer 57 is arranged, and thereon is arranged a layer of lubricating power 58. Optionally, the polymeric coating can be applied to the inner zone of the radiopaque coil 56 and around the soul and the braided threads. Optionally, the braided yarns can have polymers within the tubular braided structure.

It is accepted that the relative position between the core and the stranded wires at the tip of the wire, described in this document, can be modified. Various braided distal tip configurations for guide wires 70a, 70b, and 70c, respectively, are illustrated in Figures 5A to 5C. The central core 74 is the same for all guide wires, comprising a proximal part 71, a distal part 73 and a taper zone 72. In Figure 5A, braided material 75a is attached to taper area 72 by a weld 76 and does not extend to distal end 77a. Figure 5B is similar to Figure 5A and shows a guidewire 70b in which the braided material 75b is attached to the taper area 72 by a weld 76 and is attached to the distal end of the web 77b by a weld 78. In Figure 5C, braided material 75c of guidewire 70c is attached to taper area 72 by a weld 7 6 and extends beyond distal end 77c.

An alternative embodiment according to the present invention is illustrated in Figure 6. The braided wires 92 run the entire length, may be attached to the core 90 at the proximal and distal ends of the guidewire and optionally at intermediate points. The core of the wire has various geometric shapes at the distal end, as shown in Figures 1A to 1H or in Figures 3B to 3D. The polymeric substance can be disposed within the braided tubular core, around the core (as in Figure 1A), and on the braided wires.

Preferably, a lubricity coating layer is disposed on the polymer. The advantages of this type of guide wire are that it is extremely robust over its entire length; there are no bonds / welds / transitions to consider when advancing the catheter along the wire; and also a great torque capacity at the tip. With this embodiment it is possible to obtain less friction when advancing the catheter, because the wavy surface of the wire is smooth.

Shown in Figure 7 are twisted wires 105 that are helically wound around a central core 104. The central core can be a polymer, a composite material, contain ceramic, metal, or any suitable substrate that allows for uniform winding of the wires. The central core 104 can be integrated into one of the guidewires shown above, or it can be removed to allow the braided wires 105 to be used in other structures shown above. One or more stranded yarns may comprise radiopaque materials, for example platinum, a platinum / iridium alloy, tungsten, plated composite materials known as DFT yarns, coated materials or other materials known in the art.

Manufacturing procedure

A guide wire according to the present invention can be made by wrapping turns of the intended diameter around a mandrel or support core. The individual wires are wound into coils, which are loaded into a braiding machine. Each of the wires is led under tension through the vertex of the braiding machine and wound around a support mandrel. For example, a helical pattern is advisable. The wires wound in this way are oriented at an angle between 10 and 80 ° relative to the longitudinal axis of the support mandrel.

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The wire is drawn from the coils and spirally wound around the support mandrel as it is fed into the braiding machine. Rollers that are in contact with the wires before and after the apex can be used to control the degree of tension to which the wires are subjected as they are wound onto the support mandrel. For some materials, heat is applied behind the vertex to maintain the shape. The temperature used depends on the composition of the wires. For example, nitinol is treated at temperatures between 450 ° C and 550 ° C. Some metals, such as platinum, gold, or annealed stainless steel, are flexible enough for the aforementioned heat treatment. The braided material / support mandrel is cut into pieces of a certain length and the braided wires are separated from the support mandrel. The braided material is then trimmed to the desired length and placed over the shaped distal end of the guidewire.

Six twisted wires are illustrated in Figure 8, the angle 6> (theta) being 45 °. The figure also shows a relatively tight helical winding. The amplitude of the turns is very different from that shown in figure 7, which is approximately 33 °. For the stranded strand wires used in accordance with the present invention, angles between 10 and 45 degrees are generally preferred, and angles between 15 and 30 degrees are particularly preferred. These values ​​provide good resistance to the tip, without the risk of elongation or fracture during use.

The above description and drawings are provided for the purpose of describing embodiments according to the present invention and are not intended to limit the scope of the invention in any way. For this reason, the present invention is intended to cover modifications and variations of the invention, provided they are within the scope of the appended claims and their equivalents.

Documents cited in the specification

The following list of documents mentioned by the applicant has been produced exclusively for the information of the reader and is not part of the European patent document. It has been elaborated with great care; however, the European Patent Office assumes no responsibility in the event of eventual errors or omissions.

Patent documents cited in the specification • WO 9213483 A [0001] • US 5067489 A [0029]