JP2009523481A - Titanium / molybdenum alloy guide wire - Google Patents

Abstract

  Medical guide wire for use in vascular and non-vascular systems. It is made of a titanium-molybdenum alloy having a composition of about 78% titanium, about 11.5% molybdenum, about 6% zirconium, and about 4.5% tin by weight, and is softer than a stainless steel guidewire Thus, the rigidity is higher than that of the NiTi alloy guide wire. The distal end of the guide wire is smaller in diameter and softer than the proximal end, and a coil is attached to give elasticity so that the distal end is curved when the curved portion is encountered in the body passage. . The tip is heat treated to provide a softness gradient, and the tip is softest. The tip may be tapered to provide an additional soft gradient. The guidewire tip does not pierce the passage wall as the guidewire passes through the passage. The guide wire has intermediate properties between a stainless steel guide wire and a NiTi alloy guide wire for good torsional and rigid properties.

Description

  The present invention relates to a medical device, and specifically relates to a guide wire mainly used in an intravascular procedure. A guide wire made of a titanium / molybdenum alloy provides a flexible, moldable tip with low kinking, high torque, high trajectory followability, and high column strength.

  The main requirement for guide wires and other guide members, whether solid or tubular, is to push through the patient's passageway, such as the vasculature, with minimal kinking or tying. It has sufficient column strength. However, the distal portion of the guidewire must be sufficiently flexible to avoid damage to the blood vessel or other body cavity through which it is advanced. Efforts have been made to improve both their strength and flexibility in order to make these guidewires more suitable for their intended use, but with the strength to push and without damaging the vessel wall Flexibility to change direction is in the exact opposite relationship that one increase is usually accompanied by a decrease in the other. Commercially available intravascular catheters and guidewires, particularly for use in the coronary arteries, have progressively reduced contours or transverse dimensions. However, concomitant with the reduction in contour is the pressure advancement and loss of kinking resistance.

  The tip of this guidewire is tapered and thin, and therefore often has a spring or coil around a soft metal core. This thin, soft core may be too thin to engage the coil, and therefore the bent coil may be twisted.

  Guidewires are made of many different materials. The most popular materials are stainless steel and Ni-Ti alloys such as Nitinol.

  Stainless steel guidewires are prone to kinking. Although they are good to push, they are not flexible enough to bend easily within the vasculature. Stainless steel has good torque characteristics for rotating the guidewire, but does not easily deflect and therefore tends to become tangled during rotation. Once this guide wire is tangled, it must be discarded and replaced with a new guide wire.

  Ni-Ti guidewires tend to be excessively resilient, especially when traversing through tortuous paths in blood vessels, and tend to go straight or return to their initial shape, so that they have a forward pushability. not good. A Ni-Ti guidewire will be easily caught when it is rotated along a curved path. Since the Ni—Ti guidewire is elastic, it cannot be applied with rotational force as easily as stainless steel. Ni-Ti guidewires tend to have good shape memory properties. This shape memory characteristic makes it difficult for the physician to shape the guidewire tip with his / her finger to access the hard-to-reach part of the patient's vasculature.

  The guidewire needs to have a tip that is soft and does not strike the vessel wall in order to bend and turn in the vessel when advanced.

  The most popular guidewires are made of stainless steel or Ni-Ti alloy. Both these materials have advantages and disadvantages. In order to improve the performance of the guidewire, different guidewire materials are sought in order to have the same number of drawbacks and the desired quality of both.

  Titanium-molybdenum alloys used to make guidewires for body passages have several advantages over Ni-Ti and stainless steel guidewires. Titanium-molybdenum alloys have high springback properties and flexibility that is between the values of stainless steel and Ni-Ti alloys, the two most widely used metals for making guidewires.

  Titanium / molybdenum alloy has a moderate rigidity of about 42% of stainless steel, excellent torque transmission, and formability. Titanium-molybdenum alloys are softer and more flexible than stainless steel to obtain better curvature during passage through the body passage and are less likely to pierce the walls of the body passage. Also, titanium-molybdenum alloys are easier to transmit torque than stainless steel, which tends to become tangled when the guidewire is in a non-linear passage. Titanium-molybdenum alloy is stronger and better in press advanceability than Ni-Ti alloy, has relatively low elasticity, and is not as good as Ni-Ti alloy in a non-linear path. Since the guide wire can be easily rotated without being connected to the blood vessel wall, torque transmission is easy.

  Titanium-molybdenum alloys can be easily welded or brazed using standard manufacturing techniques, unlike Ni-Ti alloys that are not easily welded or brazed.

  Titanium / molybdenum alloy can be tapered in a stepped shape at the tip to give a soft gradient with the softest tip. This increases the flexibility of the tip and allows the tip to bend along the curve without puncturing the tissue in the body passage. The titanium-molybdenum alloy core is soft and can be made thick so that the coils around the core engage with a large diameter and do not entangle during bending.

The titanium-molybdenum alloy guide wire can be provided with a plastic coating such as Teflon (registered trademark) or a hydrophilic coating in order to make it slippery.
Preferably, the titanium-molybdenum alloy is a mixture of about 78 wt% titanium, 11.5 wt% molybdenum, 6 wt% zircon, and 4.5 wt% tin.

It is an object of the present invention to provide a guidewire having a suitable amount of rigidity for easy advancement.
An object of the present invention is to provide a guide wire having an appropriate size of flexibility so as to bend along a curved portion of the passage without puncturing the wall of the passage.
An object of the present invention is to provide a guide wire having a rotation characteristic so that torque can be transmitted without being bound in a non-linear passage.
An object of the present invention is to provide a guide wire in which a coil is provided at a distal end portion of a guide wire which is less kinked when bent.

An object of the present invention is to provide a guide wire having a soft gradient at the tip.
An object of the present invention is to provide a guide wire with good maneuverability in a body passage of a patient.
An object of the present invention is to provide a guide wire that is easy to weld and braze.
It is an object of the present invention to provide a guidewire having an easily shaped tip.

An object of the present invention is to provide a guide wire having a radiopaque tip.
It is an object of the present invention to provide a guide wire that has greater kinking resistance than a stainless steel guide wire.
An object of the present invention is to provide a guide wire that is less elastic than a Ni-Ti alloy guide wire.
It is an object of the present invention to provide a guidewire having a coating for facilitating advancement within a patient's vasculature.

  Other objects, advantages and novel features of the invention will become apparent from the following description of the invention when taken in conjunction with the accompanying drawings.

  Guidewires used in patient body passageways are used in many medical procedures. Many medical procedures use a guide as a guide wire to insert catheters and other instruments into the patient's vasculature. The guide wire is made of stainless steel, is rigid and does not easily curve in the patient's body passage. Guidewires are often made of Ni-Ti alloys that are softer and more resilient than stainless steel and have good memory properties, but are not as rigid and do not have as much pressure advancement properties as stainless steel . In addition, Ni—Ti alloy does not bend easily, and the tip cannot be easily formed.

  FIG. 1 shows a titanium / molybdenum alloy guide wire having intermediate characteristics between stainless steel and Ni—Ti alloy. Titanium-molybdenum alloys are easy to use and have better torque characteristics, softness, and push advancement than guidewires made of other materials for use in patient body passages.

  The guidewire of FIG. 1 is formed of a titanium-molybdenum alloy containing about 78% titanium, 11.5% molybdenum, 6% zircon, and 4.5% tin. The stiffness is about 42% of stainless steel.

  As a variant, the guidewire can be made of an alloy with a range of values. The range of values is about 75-83 wt% titanium, 8-14 wt% molybdenum, 4-8 wt% zircon, and 2-6 wt% tin.

  Titanium / molybdenum alloy can be bent more than 42% more than stainless steel without permanent deformation, has a low force / deflection rate, high springback characteristics, and high flexibility.

  When stainless steel is compared to Ni-Ti alloy, Nitinol, stainless steel causes distortions that are not desirable properties for guidewires, and Nitinol is excessively resilient, which is not desirable properties for guidewires . If the guidewire stiffness is excessive, it will be distorted and will not bend easily. However, the stiffness provides good push advancement to allow the guide wire to be inserted into the passage and also causes rotation at the distal end when the guide wire is turned at the proximal end. However, if the guidewire does not bend easily and there is a non-linear passage through which the guidewire must pass, the rigidity of the guidewire will create an arch along the curved portion of the guidewire and guide The whole wire will tend to push the passage wall and will not rotate easily. If the guidewire is too elastic and the guidewire rotates, it will stay in the curved portion of the passage.

  Titanium / molybdenum alloy guidewires are less elastic than Ni-Ti alloys, but more elastic than stainless steel. Titanium / molybdenum alloys have greater rigidity than Ni—Ti alloys, but not as rigid as stainless steel. Therefore, titanium-molybdenum alloys have desirable properties for guide wires.

  FIG. 2 shows relative stress / strain curves comparing a Ni—Ti alloy guide wire: curve 35, a stainless steel guide wire: curve 30 and a titanium / molybdenum alloy guide wire: curve 33. FIG. This graph shows the percentage of maximum bending moment (in-lbf = 0.113 N-m) related to declination (degrees). It indicates the percentage that each wire returns to its original shape after bending to a given moment. As shown in this chart, when bent, Nitinol returns to its shape, stainless steel returns to only about 5% of its original shape, and titanium-molybdenum alloys such as Beta III alloys Return to about 50% of its original shape. Thus, titanium-molybdenum alloys, such as beta III alloys, exhibit intermediate springback characteristics between nitinol and stainless steel.

  FIG. 1 shows a side view of a guidewire 10 having a proximal end 12 and a distal end 14. The distal end 14 is smaller in diameter than the proximal end 12 to allow it to bend softly and easily. The tip 14 is preferably soft so that the guide wire is curved and follows the curve of the blood vessel or other passageway through which the guide wire is inserted. The guide wire has a tip 16 rounded to the tip 15 to secure the coil 18 to the tip 14 and prevent the tip 15 from penetrating the tissue of the passage when the guide wire is inserted. The guidewire 10 also includes a coil 18, which is made of platinum, tungsten or similar radiopaque material and acts as a spring, curving the narrowed tip 14 but passing the guidewire through the passageway. After carrying around the curved part, it springs back in place.

  In the past, if there was a large space between the inner diameter of the coil 18 and the core of the tip 14 of the guidewire 10, the coil 18 would be kinked and not tend to return to their original shape. Titanium-molybdenum alloy is soft when the outer diameter of the tip of the guidewire 10 engages with the coil 18 at the inner diameter to reduce the space between them and the coil 18 and the tip 14 bend. In order to prevent the coil from twisting, it is possible to have a large diameter but still be sufficiently soft at the tip 14. The coil 18 is wound around the core of the tip portion 14 in close contact with the core so that there is no space between the windings and no kinking occurs when the guide wire is bent.

  The titanium-molybdenum alloy is made soft by tapering the tip 14 to reduce the cross section of the guide wire. Tapering the tip 14 provides a soft gradient, with the tip 15 being the softest. This soft gradient helps to bend the tip while keeping the rest of the guidewire 10 straight. The tip 14 can have a tapered portion 20 that gradually changes the diameter of the guidewire material, providing a soft gradient.

  A sudden change in the stiffness of the guide wire tip causes kinking at the stress point of the core when the tip is bent. By gradually changing the diameter and increasing the number of turns of the taper portion, the softness (curvature characteristic) of the guide wire is continuously increased toward the distal end portion 14 of the guide wire without sudden change, thereby preventing kinking. Can do.

  The proximal end portion 12 of the guide wire is less flexible and more uniform, and can transmit torque and pressing forward force with high fidelity.

  Titanium / molybdenum alloy is more flexible than stainless steel, but has sufficient rigidity to give a rotating force and is more rigid than Ni-Ti.

  The distal end portion 16 of the coil 18 is attached to the titanium-molybdenum alloy guide wire 10 by welding or brazing. Titanium / molybdenum alloys are welded or brazed more easily than Ni—Ti alloys.

  The guide wire 10 can be coated with plastic to make it easier to slip. The guide wire can be coated with a Teflon coating or a similar material for hydrophilic coating.

  The proximal end 12 of the guidewire 10 can have a coating or surface that facilitates gripping for the physician to use the guidewire more effectively.

  The guide wire 10 can preferably have a length of 20 to 500 cm, a diameter of 0.127 to 1.016 mm, and preferably a coil length of 0.5 to 100 cm.

  The guidewire 10 has a coil made of platinum, tungsten or similar material to help make the coil radiopaque so that it can be easily seen in the imaging apparatus and visible during use. Can do.

  Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is needless to say that the present invention can be implemented by methods other than those specifically described within the scope of the claims.

The side view of a guide wire. The graph which compares the stress-strain curve of a Ni-Ti alloy, stainless steel, and a TiMo alloy.

Claims (10)

In an intravascular guidewire suitable for insertion into a patient's vasculature during a catheterization procedure,
A titanium-molybdenum alloy wire having about 78 wt% titanium, 11.5 wt% molybdenum, 6 wt% zircon, and 4.5 wt% tin;
The wire has a diameter ranging from 0.127 mm to 1.016 mm over a predetermined length dimension, the wire having a proximal end and a distal end, the distal end being tapered and A guidewire that is smaller in diameter than the proximal end and ends with a rounded tip.   A tip portion to which a helical coil is attached, wherein the coil is in contact with the tip of the guide wire, and the coil provides elasticity at a position near the tip to prevent the coil from being twisted. Item 2. A guide wire according to item 1.   2. The tip member according to claim 1, further comprising a tip member rounded to a tip portion of the wire so that the tip of the wire does not penetrate the tissue of the wall of the body lumen when the guide wire is passed through the body lumen. Guide wire.   The guide wire of claim 1, wherein the wire has a smooth polymer coating.   The guide wire of claim 1, wherein the wire has a hydrophilic coating. In an intravascular guidewire suitable for insertion into a patient's vasculature during a catheterization procedure, titanium is about 75% to about 83%, molybdenum is about 8% to about 14%, zircon is about 4% to about 8%. A titanium-molybdenum alloy wire having a weight percent and about 2 weight percent to about 6 weight percent tin;
The wire has a diameter ranging from 0.127 mm to 1.016 mm over a predetermined length dimension, the wire having a proximal end and a distal end, the distal end being tapered and A guidewire that is smaller in diameter than the proximal end and ends with a rounded tip.   The guide wire according to claim 6, further comprising a coil attached to a tip member, wherein the coil imparts elasticity to the tip portion to prevent kinking of the coil.   The guide wire according to claim 6, wherein a distal end member is provided at the distal end portion so that the distal end of the wire does not penetrate the tissue of the wall of the body passage.   The guide wire of claim 6, wherein the wire has a smooth polymer coating. The guide wire of claim 6, wherein the guide wire has a hydrophilic coating.

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