Twisted guide wire

Abstract

A guidewire with improved torque characteristics in the proximal portion. The proximal portion has a square cross-section and multiple twists along its length. The multiple twists have a pitch of 1 to 3 twists per 1.0 inch, resulting in the guidewire having a torque delay of less than 15° when the proximal portion is subjected to torsional force.

Description

Technical Field

[0001] The technology of this specification relates to the field of guide wires for advancing intraluminal devices such as stent delivery catheters, balloon dilation catheters, and atherectomy catheters within a body cavity.

Background Art

[0002] In general, torque may be applied to a guidewire to facilitate navigation in winding vessels, and to facilitate therapeutic procedures such as the placement of balloon dilation catheters and corresponding stent devices in arteries and veins within the aortic, iliac, femoral, popliteal, and infrapopliteal regions, but not limited to these. In a typical coronary procedure, a guiding catheter with a pre-formed distal end is introduced percutaneously into the patient's artery, e.g., the femoral or brachial artery, using the conventional Seldinger technique, and advanced within it until the distal end of the guiding catheter seats in the desired coronary artery opening. There are two basic techniques for advancing the guidewire to a desired position within the patient's coronary artery structure: the first is the preload technique, primarily used with over-the-wire (OTW) devices, and the second is the bare-wire technique, primarily used with rapid-change systems. In the preloading technique, the guidewire is positioned within the inner lumen of an OTW device, such as an dilation catheter or stent delivery catheter, with its distal end just proximal to the distal end of the catheter, and then both are advanced through the guiding catheter to its distal end. The guidewire is first advanced out of the distal end of the guiding catheter into the patient's coronary vascular system until its distal end crosses the arterial location where the intervention will be performed (e.g., the lesion to be dilated or the dilation area where the stent will be deployed). The catheter, slidably mounted on the guidewire, is advanced out of the guiding catheter into the patient's coronary artery structure along the previously introduced guidewire until the operating portion of the intravascular device (e.g., the balloon of the dilation catheter or stent delivery catheter) is properly positioned across the arterial location. Once the catheter is positioned with the operating portion located within the desired arterial location, the intervention is performed. The catheter can then be removed from the patient along the guidewire. Typically, the guidewire is left in place for a certain period after the procedure is completed to ensure re-access to the artery.

[0003] In bare-wire technique, the guidewire is first advanced alone through the guiding catheter until its distal end passes the artery where the procedure is to be performed. A rapid-exchange (RX) catheter is then attached to the proximal portion of the guidewire, extending outward from the proximal end of the guiding catheter, which is outside the patient. The catheter is then advanced along the guidewire, keeping the guidewire in place, until the operating device on the RX catheter is positioned within the artery where the procedure is to be performed. After the procedure, the intravascular instrument may be withdrawn from the patient along the guidewire, or the guidewire may be advanced further within the coronary artery structure for additional procedures.

[0004] Conventional guidewires for angioplasty, stent delivery, atherectomy, and other vascular procedures typically comprise an elongated core member having one or more tapered sections near its distal end, and a flexible body, such as a helical coil or tubular body, made of polymer material, positioned around the distal portion of the core member. A moldable member, which may be the distal end of the core member, or a separate moldable ribbon fixed to the distal end of the core member, extends through the flexible body and is fixed to the distal end of the flexible body by soldering, brazing, or welding, forming a rounded distal tip. A torque-applying means may be provided at the proximal end of the core member to rotate and guide the guidewire while it is being advanced through the patient's vascular system.

[0005] In the best medical practice for anatomical insertion, guidewires with behavioral characteristics that vary along their length are generally required. For example, under certain conditions, the distal end of the guidewire may need to have greater flexibility than the proximal end so that it can be more easily inserted around the more tortuous distal branches of the lumen structure. Furthermore, the proximal end of the guidewire may need to have greater torsional rigidity than the distal end, as it must support all torsional forces transmitted distally along the length of the guidewire, including the torsional forces necessary to overcome cumulative frictional losses during guidewire rotation.

[0006] For example, in certain procedures such as delivering stents around difficult origins like Shepherd's curve, tortuosity, or severe curvature, substantially more support and / or vascular straightening is often required from the guidewire than can be provided by a conventional guidewire. While guidewires offering improved distal support than conventional guidewires have been commercially introduced for such procedures, such guidewires are not very maneuverable, and in some cases, they are so rigid that they can damage the vascular lining as they advance through the vessel. What has been needed but has not been available until now is a guidewire that provides a high level of distal support by providing a high degree of torque along the proximal portion of the guidewire. [Overview of the project]

[0007] A key aspect of the present invention is to provide a guidewire that has excellent torque characteristics while simultaneously reducing friction between the guidewire and the delivery system. The guidewire of the present invention increases bending stiffness and also improves proximal grip for navigating tortuous blood vessels.

[0008] In one embodiment, the guidewire comprises an elongated wire having a proximal end and a distal end. The length of the guidewire can vary considerably based on a number of factors, such as where the guidewire is inserted into the body. In one embodiment, the proximal portion of the guidewire has a length ranging from 12 inches to 120 inches, and the distal portion has a length ranging from 0 inches to 8.0 inches. At least a portion of the proximal portion has a square cross-section with four rounded corners. The proximal portion has multiple twists at a pitch of 1 to 3 twists per 1.0 inch. When subjected to torsional force at the proximal portion, the distal portion has a torque delay of less than 15°.

[0009] In another embodiment, the guidewire is structurally identical to that disclosed above, except that the proximal portion has multiple twists at a twist pitch of no more than 2 twists per inch. When subjected to a torsional force at the proximal portion, the distal portion has a rotational torque delay of less than 15°.

[0010] In all embodiments disclosed herein, the torque delay in the distal portion can be obtained from 0° rotation to 35° rotation, and still exhibits excellent torque response.

[0011] In one embodiment, the guidewire is formed from an elongated wire having a proximal end and a distal end. The proximal portion extends from the proximal end toward the distal end and has a length ranging from 12 inches to 120 inches. The distal portion extends from the distal end toward the proximal end and has a length ranging from 0 inches to 8.0 inches. The proximal portion has a square cross-section with four corners. The four corners are preferably rounded and have a radius ranging from 0.010 inches to 0.014 inches, preferably a radius of 0.012 inches. The proximal portion has multiple twists at a pitch of 2 twists per 1.0 inch. When subjected to torsional force, the distal portion has a torque delay of less than 15°. [Brief explanation of the drawing]

[0012] [Figure 1] This is a front view showing the guide wire of the present invention, which has a proximal portion with a square cross-section and a distal portion with a circular cross-section. [Figure 2] This is a front view of the guide wire of the present invention, showing the twist formed in the proximal portion of the guide wire. [Figure 3] Figure 1 shows a cross-sectional view along the guide wire line 3-3, illustrating a square cross-section with rounded corners. [Figure 4] This graph shows clockwise torque test data obtained from tests of several commercially available guide wires compared with the guide wire of the present invention. [Figure 5]This graph shows counterclockwise torque test data obtained from tests of several commercially available guide wires compared with the guide wire of the present invention. [Figure 6] This graph shows clockwise and counterclockwise test data obtained from tests of commercially available guidewires compared with the guidewire of the present invention. [Modes for carrying out the invention]

[0013] The guidewire of the present invention offers improved torque characteristics, higher bending rigidity compared to round wires, improved tactile sensation for physicians, and reduced friction between the guidewire and the catheter.

[0014] According to the present invention, as shown in Figures 1-6, the guidewire 10 is formed from an elongated wire 12 having a proximal end 14 and a distal end 16. The elongated wire has a total length 18 ranging from 20 inches (50.8 cm) to 120 inches (304.8 cm), depending on factors such as the position on the human body where the guidewire 10 is inserted. In this embodiment, the proximal portion 20 preferably has a length ranging from 12 inches (30.5 cm) to 71 inches (180.3 cm), more preferably from 40 inches (101.6 cm) to 60 inches (152.4 cm). In one embodiment, the proximal portion is 78.7 inches (200 cm). The proximal portion 20 has a square cross-section 22 with four corners 24, the four corners 24 being rounded. The four corners 24 are rounded to a radius ranging from 0.005 inches (0.127 mm) to 0.03 inches (0.762 mm). In one embodiment, the four corners 24 are rounded to a radius of 0.0108 inches (0.2743 mm).

[0015] The proximal portion 20 has multiple twists 26 with a twist pitch of 1 to 3 twists per 1.0 inch (25.4 mm). In one embodiment, the proximal portion 20 has 2 or fewer twists per 1.0 inch (25.4 mm). In another preferred embodiment, the proximal portion 20 has 2 twists 26 per 1.0 inch. When the proximal portion 20 is subjected to a torsional force (as further described herein), the distal portion 28 has a torque delay in the range of 0° to 35°. Preferably, the torque delay in the distal portion 28 is in the range of 0° to 15°. In one embodiment, the torque delay in the distal portion 28 is less than 15°. The distal portion 28 has a length 30 in the range of 2.0 inches (5.08 cm) to 8.0 inches (20.32 cm). In one embodiment, the length of one pitch or twist 26 is in the range of 0.2 inches to 1.0 inch, preferably the pitch length is 0.5 inches.

[0016] The length of the guidewire is well known in the art and can range from 180 cm to 300 cm for coronary artery applications, and can be significantly shorter for other applications. Importantly, the proximal portion 20 may be substantially longer than the distal portion 28 of the elongated wire 12. For example, in the case of a standard 70.87 inch (180 cm) long guidewire 10, the proximal portion 20 can range from 37.40 inches (95 cm) to 70.87 inches (180 cm), preferably from 64.96 inches (165 cm) to 68.90 inches (175 cm).

[0017] The guidewire 10 is preferably formed from any superelastic or linear elastic material known in the art, and more preferably from nitinol. The guidewire 10 may be formed from stainless steel, titanium, and other metal alloys including cobalt-chromium.

[0018] A polymer cover (not shown) may be formed from any polymer known in the art for use with the guidewire, catheter, and stent. The elongated member 12 is optionally coated with a lubricating coating, such as a fluoropolymer (e.g., TEFLON®), extending over the length of the proximal core portion. Hydrophilic coatings may also be used. The diameter of the guidewire 10 may be modified to suit the specific procedure and constituent materials to be used. Guidewire diameters generally range from about 0.008 inches to about 0.035 inches (0.203 mm to 0.889 mm), more typically from about 0.012 inches to about 0.018 inches (0.305 mm to 0.547 mm), preferably about 0.014 inches (0.336 mm) for coronary artery structures and 0.018 inches (0.547 mm) and 0.035 inches (0.889 mm) for peripheral artery structures.

[0019] The guidewire 10 disclosed herein may be formed in several configurations. For example, as shown in Figures 1-3, the proximal portion 20 may be formed from stainless steel and have a square cross-section (Figure 3). The stainless steel proximal portion 20 is solid-welded to a distal portion 28 having a circular cross-section. The distal portion 28 is formed from nitinol (NiTi) or a similar superelastic material well known in the art. The four corners 24 of the square cross-section proximal portion 20 are generally rounded by grinding, as well as well known in the art. The radius of the rounded corners 24 may vary as described herein.

[0020] The proximal end 14 of the proximal section 20 is fixed to a machine to impart a disclosed number of twists 26 per unit length. The proximal section 20 is rotated by the machine while the distal end of the proximal section is held stationary, thereby forming the twists 26 in the proximal section. Depending on the twist pattern and diameter of the guidewire, a grinding wheel having a width of 0.5 to 2 inches may be used to further form the twists 26 and to round the four corners 24. This twist pattern is imparted only to the proximal section 20. In one embodiment, several twists 26 are formed along the length of the proximal section 20, but not along its entire length. The twists 26 may be formed alternately with the untwisted sections of the proximal section. Furthermore, the number of twists 26 per unit length may vary along different sections of the proximal section 20. In one embodiment, the twists 26 are formed in the proximal section 20 before it is welded to the distal section 28.

[0021] Guidewires 10 of several prototypes of embodiments disclosed herein were tested for torque delay compared to commercially available guidewires having a twisted pattern. Ideally, a physician would want a guidewire with a 1:1 torque response ratio (i.e., a 90° rotation at the proximal end results in a 90° rotation at the distal end). Thus, the torque delay at the distal end is 0°. Torque test data were collected for prototypes 1 and 2 (having a square cross-section) of the present invention compared to product 1 (a commercially available guidewire having a circular cross-section), as shown in Figures 4-6. Differences in the test data results depend on many factors of the guidewire being tested, including cross-sectional shape, metal alloy, length, diameter, and the position and number of twists per unit length. Prototypes 1 and 2 have a square cross-section with twists in the proximal portion, while product 1 has a core with a circular cross-section. Therefore, the test data are presented for comparison purposes only.

[0022] The test was conducted by inserting the proximal end of the guide wire into a machine that firmly grips the proximal end. The guide wire was stretched using a video camera focused on the distal end. Then, the machine rotates the proximal end 90° in either the clockwise or counterclockwise direction, the system pauses for a few seconds to recover the accumulation, and then the distal end is observed using the video camera to determine the amount of torque delay (rotation) that occurred at the distal end. After observing the degree of torque delay at the distal end 16 of the guide wire, the machine rotates the guide wire an additional 90° (for a total of 180°) clockwise (Figure 4) or counterclockwise (Figure 5), and again, the distal end is observed by the video camera for torque delay. The same process was repeated for 270° and 360° rotations at the proximal end of the guide wire.

[0023] As shown in Figures 4 and 5, the degree of rotation of the proximal end is on the Y-axis, and the guide wires being tested are shown on the X-axis. As shown in Figure 4, with a 90° clockwise rotation applied to the proximal end, the guide wire of Prototype 2 had a very low torque delay response of about 4° to 15°, while the guide wires of Prototype 1 and Product 1 had a relatively high torque delay compared to Prototype 2. Ideally, a torque delay within the range of 0° to 35° is desirable, and a torque delay within the range of 0° to 15° is more preferable. Figure 5 shows similar results when the guide wire is rotated counterclockwise or torque is applied. The difference in torque delay data between clockwise and counterclockwise rotations at the proximal end is partially explainable by the direction of the twist of the wire being tested.

[0024] As shown in Figures 4 and 5, at a 180° rotation at the proximal end of the guidewire, the Prototype 2 and Product 1 guidewires exhibited similarly good torque delay results. However, the Prototype 1 guidewire showed energy accumulation and a higher torque delay at the distal end 16, which is undesirable because it is difficult to predict how the distal portion 28 and distal end 16 will function. At a 360° rotation at the proximal end 20 of the guidewire under test, all distal ends 16 of the guidewire under test were able to catch up and showed a torque delay of 0°.

[0025] Figure 6 shows a variability diagram representing the displacement (degrees) of the distal end of the guidewire. Figure 6 is a graphical representation of the data generated when the distal end of the guidewire passes through a simulated fixation device and the tip of the guidewire is held in a chuck to which a sensor is attached. The proximal end of the guidewire is torqued 360° clockwise, returned to the neutral position, and then torqued 360° counterclockwise. The sensor measures the torque delay at the distal tip of the guidewire. Although the present invention is illustrated and described herein in relation to its use as a guidewire, it will be apparent to those skilled in the art that the guidewire can be used in all blood vessels of the body. All dimensions disclosed herein are given as examples only. Other modifications and improvements can be made without departing from the scope of the present invention.

Claims

1. It is a guide wire, An elongated wire having a proximal end and a distal end, A proximal portion having a length ranging from 12 inches to 120 inches and a distal portion having a length ranging from 0 inches to 12 inches, A guide wire equipped with, The proximal portion has a square cross-section with four corners, and the four corners are rounded. The proximal portion has multiple twists at a twist pitch of 1 to 3 times per 1.0 inch. The distal portion of the guidewire has a torque delay of less than 15° when the proximal portion is subjected to a torsional force.

2. The guide wire according to claim 1, wherein the guide wire has a diameter in the range of 0.014 inches to 0.035 inches.

3. The guide wire according to claim 2, wherein the elongated wire has a length of 120 inches.

4. The guide wire according to claim 2, wherein the elongated wire has a length of 71 inches.

5. The guide wire according to claim 2, wherein the four rounded corners have radii ranging from 0.005 inches to 0.127 inches.

6. It is a guide wire, An elongated wire having a proximal end and a distal end, A proximal portion having a length ranging from 12 inches to 120 inches and a distal portion having a length ranging from 0 inches to 12 inches, A guide wire equipped with, The proximal portion has a square cross-section with four corners, and the four corners are rounded. The aforementioned proximal portion has multiple twists at a twist pitch of 2 or fewer twists per 1.0 inch. The distal portion of the guidewire has a torque delay of less than 15° when the proximal portion is subjected to a torsional force.

7. The guide wire according to claim 6, wherein the guide wire has a diameter in the range of 0.014 inches to 0.035 inches.

8. The guide wire according to claim 7, wherein the elongated wire has a length of 120 inches.

9. The guide wire according to claim 7, wherein the elongated wire has a length of 71 inches.

10. The guide wire according to claim 7, wherein the four rounded corners have radii ranging from 0.005 inches to 0.127 inches.

11. It is a guide wire, An elongated wire having a proximal end and a distal end, A proximal portion having a length ranging from 12 inches to 120 inches and a distal portion having a length ranging from 0 inches to 12 inches, A guide wire equipped with, The proximal portion has a square cross-section with four corners, and the four corners are rounded. The aforementioned proximal portion has a twist pitch of 2 twists per 1.0 inch, The distal portion of the guidewire has a torque delay of less than 15° when the proximal portion is subjected to a torsional force.

12. The guide wire according to claim 11, wherein the guide wire has a diameter in the range of 0.014 inches to 0.035 inches.

13. The guide wire according to claim 12, wherein the elongated wire has a length of 120 inches.

14. The guide wire according to claim 12, wherein the elongated wire has a length of 71 inches.

15. The guide wire according to claim 12, wherein the four rounded corners have a radius of 0.005 inches to 0.127 inches.

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