WO1992014508A1

WO1992014508A1 - Torsionally stable guidewire

Info

Publication number: WO1992014508A1
Application number: PCT/US1992/001217
Authority: WO
Inventors: Vern L. Leibmann; Scott J. Solano
Original assignee: Mallinckrodt Medical, Inc.
Priority date: 1991-02-15
Filing date: 1992-02-13
Publication date: 1992-09-03
Also published as: AU1428792A

Abstract

The present invention relates to guidewires used for the insertion of catheters into the vascular system of a living being. In particular, the present invention relates to angioplasty guidewires used for guiding balloon catheters into the vascular system, such balloon catheters being used for treatment of arterial vascular blockage. The guidewires according to the present invention allow for the varying of the flexibility of the guidewire tip in order to optimize pushability and maneuvrability, and also exhibits enough stiffness to allow torque to be transmitted from the proximal end to the distal end of the guidewire, without causing collapse or expansion of the tip. Further, the present invention relates to a guidewire which may be used to deliver drugs or other agents to particular internal locations within a living being.

Description

TORSIONALLY STABLE GUIDEWIRE

Background of the Invention

The present invention relates to guidewires used for the insertion of catheters into the vascular system or other organs or systems of a living being. In particular, the present invention relates to angioplasty guidewires used for guiding balloon catheters into the vascular system, such balloon catheters being used for treatment of arterial vascular blockage. Further, the present invention relates to a guidewire which may be used to deliver drugs or other agents to particular internal locations within a living being.

Catheters are used in numerous procedures for the treatment of disorders or various organs or systems of a living being. In particular, catheters are often used to administer drugs directly to an organ or system which is hard to access by other means; such as, areas of the general vasculature system, for example, distal arteries of the lower leg, renal arteries, etc. Further, catheters are often used in neuroradiology procedures in order to open blood vessels, for example by the injection of drugs; or to close blood vessels, for example by use of an embolization agent or device. Moreover, catheters are often used in the treatment of general disorders to organs and systems of the living being, such as the fallopian tubes, etc. In all of the examples of using a catheter described above, it is usually necessary to first insert a guidewire into the living being and to maneuver the guidewire into the desired area of treatment. The catheter may then be threaded over the guidewire and pushed along the guidewire in order to reach the desired treatment area.

Two techniques of treating lesions or blockage of the vascular system are percutaneous translirmenal angioplasty

SUBSTITUTE SHEET (PTA) and percutaneous translumenal coronary angioplasty

(PTCA) using a balloon catheter. While PTA techniques are used primarily for non-heart arteries, PTCA techniques are used in arteries which effect the blood supply to the heart. In these techniques, a guidewire of relatively fine diameter is first inserted directly into the vascular system of the patient and then is steered and manipulated through the vascular system until it crosses the area of lesion or blockage which it is desired to treat. The balloon catheter is then inserted over the guidewire, and is pushed through the vascular system following the path of the guidewire, until the balloon portion of the catheter is properly located within the area of lesion or blockage.

Because the vascular system and body passages through which the guidewire must pass are generally sinuous and irregular, and also connect with other passages at various and sometimes sharp angles, manipulation of the guidewire is a difficult and delicate process. Therefore, a guidewire must be torsionally stable to the extent that when the proximal end of the guidewire is rotated, torque is transmitted to the distal tip of the guidewire, without kinking or breaking. Further, a guidewire must have enough flexibility at the distal tip to assure safe passage through the fragile vascular system or passages and to assure relatively easy manipulation through the tortious curves and angles of the vascular system or passages necessary to reach the desired location.

There are several guidewires known in the prior art, which are designed to provide a combination of torsional stability and flexibility. While there are some guidewires for general applications known in the prior art that allow for varying the flexibility of the distal tip of the guidewire, such guidewires do not generally possess enough

SUBSTITUTE SHEET, torsional stability to allow the transmission of torque from the proximal end of the guidewire to the distal end of the guidewire.

International published application WO 90/05486 describes a small diameter guidewire which is formed of a coil structure with a sheath disposed thereabout, the combination thereof having a torque response along the joined length approaching 1:1. This application claims that such a structure allows control of the distal tip of the guidewire by application of rotational forces to the proximal end. However, this application does not describe means for varying the flexibility of the distal tip of the guidewire.

It is therefore believed that no angioplasty guidewires known in the prior art, provide both a means of varying the flexibility of the distal tip of the guidewire, and also possess enough torsional stability to allow torque to be transmitted from the proximal end to the distal tip of the guidewire.

In the prior art, torsional stability is provided by use of a single, continuous corewire, which is formed of a material having a sufficiently high strength modulus to assure that torque may be transmitted from the proximal end to the distal tip. A common material used is stainless steel, or the like. Flexibility of the distal tip in this type of guidewire, is provided by tapering down the distal end of the corewire (generally over the distal 30 cm of the corewire) . The tapered portion of the corewire is then covered with a radiopaque metal coil in order to increase flexibility and to provide means to fluoroscopically visualize the guidewire when it is inserted into the vascular system. U.S. patents 4,545,390 to Leary;

SUBSTITUTE SHEET 4,538,622 to Sampson; 4,719,924 to Crittenden; and 4,721,117 to Mar; each describe guidewires as described above, e.g. a tapered corewire having a metal coil at the distal end. However, these prior art guidewires do not have any way of varying the flexibility of an individual guidewire at the distal end, and therefore do not possess optimum maneuverability. Rather, in order to have different flexibilities available, several separate guidewires are required, each having a differently configured distal end. Therefore, if it is found during insertion of a guidewire that more or less flexibility is required to push the guidewire past a particular curve of turn, then the first guidewire must be removed, and a second guidewire possessing the newly desired flexibility must be inserted.

U.S. patent 4,873,983 to Winters, teaches a guidewire which includes a helically wound tapered spring attached to a length of hollow tubing, through which a corewire may be variable extended or retracted to control the curvature and flexibility of the spring. Therefore, this prior art guidewire provides means of continuously optimizing the flexibility of the guidewire as it is pushed through the vascular system. However, this guidewire is disadvantageous in that there is no means provided by which adequate torque may be transmitted from the proximal end to the distal end. In particular, upon rotation of the proximal end of the guidewire, the tapered spring at the distal end tends to collapse or expand, rather than rotate.

Therefore, there is a need for a guidewire that not only allows varying of the flexibility of the guidewire tip in order to optimize pushability and maneuverability, but also provides enough stiffness to allow torque to be transmitted from the proximal end to the distal end,

SUBSTITUTE SHEET without causing collapse or expansion of the tip. Further, there is a need for a guidewire which may be used to directly deliver drugs and the like to particular locations in the body of a patient without the need for a catheter.

Obπects of the Present Invention

It is an object of the present invention to provide a guidewire which provides the needs described above.

In particular, it is an object of the present invention to provide a guidewire which allows for the variation in the flexibility of the guidewire tip so as to optimize pushability and maneuverability of the guidewire at different stages of the insertion of the guidewire into a patient.

Further, it is an object of the present invention to provide a guidewire that has the flexibility described above, and also exhibits means to transmit torque from the proximal end of the guidewire to the flexible distal tip.

In addition, it is an object of the present invention to provide a guidewire for direct delivery of drugs or other agents to particular locations within a patient.

Summary of the Present Invention

The present invention relates to a device comprised of an outer core through which torque may be transmitted from the proximal end to the distal end, without the need for a fixed corewire. By elimination of the fixed corewire, as an essential element of the device, a continuous lumen within the outer core is created which runs the length of the outer core. This lumen may be utilized to allow the

SUBSTITUTE SHEET passage of separate and discrete devices through the device, such as a oveable tapered corewire for varying the shape and flexibility of the device tip, optical fibers for various well known applications, electrical leads for attachment to various sensors, etc. Further, the central lumen may be used to administer small quantities of drugs or the like directly to a treatment site.

The device according to the present invention comprises a long thin metal cylinder with a cylindrical segment of wire filaments attached at the distal end. In order to give this structure the required torque transmission capability, the wire filaments are formed or treated in such a way that relative movement between adjacent filaments of the wire is prevented or substantially reduced when a torsional moment is applied to the device.

Details and preferred embodiments of the present invention will be discussed below.

Brief Description of the Drawings

Fig. 1 is a cross sectional view of a device according to one embodiment of the present invention.

Fig.2 is a cross sectional view of a device according to a second embodiment of the present invention.

Detailed Description of the Present Invention

Figs. 1 and 2 are cross sectional views of a device according to the present invention. The same reference numerals will be used in both drawing figures to designate similar elements of the device according to the present

SUBSTITUTE SHEET invention. Initially, the present invention will be discussed in the context of using the device as a guidewire.

A guidewire, generally designated by reference numeral 10, comprises a long tubular member 20, at the proximal end of the guidewire, and a spring member 30, made up of a segment of coiled wire filaments, at the distal end of the guidewire. In Fig. 1, a single coil of wire filaments is shown, while in Fig. 2, two coils of wire filaments are shown.

In a preferred embodiment, the tubular member 20, is a long, thin cylinder of metal, such as stainless steel, which has a sufficient length for proper insertion into the patient. For example, a stainless steel tube having an outside diameter of about .010 to .028 inch and an inside diameter of about .004 to .025 inch may be used as tubular member 20. In a preferred embodiment, the tubular member 20, is formed of a stainless steel tube with an outside diameter of about .018 inch and an inside diameter of about .010 inch. The outer surface of the tubular member 20, may be coated with a thin layer of lubricious material, such as Teflon®, polyethylene, or silicon, to make the guidewire 10, more easily insertable and moveable through the vascular system of the patient.

The spring member 30, extends for up to about fifty percent of the total length of the guidewire 10, with a preferred length of about 30 cm, and is attached to the distal end of the tubular member 20, so as to provide a smooth, continuous transition from one to the other. As can be seen in the drawing figure, the spring member 30, tapers slightly over its length, getting smaller in diameter toward a distal tip 50. The wire filaments making

SUBSTITUTE S ^* up the spring member 30, are optimally formed from a metal, such as 316L stainless steel, or from a strong polymeric fiber, such as Kevlar®. Further, the wire filaments should each have a diameter of from .001 to .005 inch, with a preferred diameter of about .003 inch, and may have a round or flat cross-section, the flat configuration having the advantage of greater strength while saving space.

A spring member as described above, is not capable of transmitting torque because of the tendency of the wire filaments to move with respect to each other when a torsional moment is applied. In other words, the adjacent wire filaments tend to contract and expand relative to one another upon application of torque, rather than transmitting the torque along the length of the spring member. Therefore, according to the present invention, the spring member 30, is treated in such a way as to prevent the relative movement of the wire filaments.

In a first embodiment according to the present invention, most clearly shown in Fig. 1, the wire filaments of the spring member 30, are braided in order to provide torsional stability. In particular, by braiding the wire filaments, the tendency of adjacent wire filaments to contract and expand may be overcome, thus enabling the spring member 30, to pass torque along its entire length. The braids of the wire filaments can be of a standard one- over-one-under, or two-over-two-under configuration, with any suitable number of plaits per inch.

In a second embodiment according to the present invention, torsional stability and flexibility are provided by using multiple, concentric coils of flat metal bands for the spring member 30. In particular, as most clearly shown in Fig. 2, at least two concentric coils of flat metal

SUBSTITUTE SHEET bands are used. While only two concentric coils are shown in Fig. 2, it is understood that three or more concentric coils may be used. By winding these coils in such a manner that the winding direction of each adjacent coil is at a different angle, the tendency toward expansion and contraction upon application of a torsional moment is overcome. In particular, the tendency of a particular coil to expand and unwind, is counteracted by the tendency of an adjacent coil to contract or wind tighter. Therefore, the overall effect is the transmission of torque along the entire length of the spring member 30, with no overall change in the dimension of the spring member 30.

The spring member 30, may be encapsulated with an encapsulating material 40, such as a soft, flexible polymeric substance. By providing the encapsulating material 40, torsional stability of the guidewire 10, can be further assured, as the encapsulation acts to fix the wire filaments of the spring member 30, in place relative to each other. The encapsulating material 40, also acts to prevent bodily fluids from seeping through the spring member 30, and into the interior of the guidewire 10. Therefore, the use of the encapsulating material 40, is desirable when the guidewire 10, is to be used for guiding a catheter to a treatment site, the catheter then being used to carry out the actual treatment. However, as will be explained below in more detail, the guidewire 10, according to the present invention may be used itself to carry out the treatment. In such a case, the encapsulating material 40, may be eliminated, or only partial encapsulation may be used.

The spring member 30, may also be treated so as to provide radiopacity. In particular, a short segment of a radiodense metal, such as platinum, gold, or tantalum, may

SUBSTITUTE SHEET be used as a portion of the filaments or coils making up the spring member 30. Further, a portion of the filaments or coils making up the spring member 30, may be encapsulated with a polymer which has been filled with a radiopaque material. Such encapsulation also has the advantage of providing greater softness to the spring member 30.

The guidewire 10, according to the present invention, has a continuous central lumen throughout the length of the tubular member 20, and the spring member 30. This central lumen may be utilized to allow the passage of separate discrete devices through the guidewire 10. In particular, a moveable tapered corewire for varying the shape and flexibility of the guidewire tip, optical fibers for various well known applications, electrical leads for attachment to various sensors, etc., may be passed through the central lumen of the guidewire 10. Further, the central lumen of the guidewire according to the present invention, may be used to administer small quantities of drugs or the like directly to a treatment site.

In a preferred embodiment, a tapered corewire may be inserted into the central lumen and may be used to control the flexibility and shape of the spring member 30. By such control, the guidewire 10, may be operated so as to function as any one of a "standard" guidewire, with the tapered corewire extending all the way through the spring member 30; or as a "flexible" guidewire, with the tapered corewire terminating about 2 cm from the distal tip 50; or as a "very flexible" guidewire, with the tapered corewire terminating about 3 cm or more from the distal tip 50. Each of the above functions may be easily achieved by simply extending or retracting the tapered corewire until the desired flexibility is obtained. In addition, the

SUBSTITUTE SHEET tapered corewire may be used to straighten the spring member 30, if such has been previously curved by a bias placed within the filaments or coils.

In a further preferred embodiment, the guidewire 10, according to the present invention is used to directly carry out a particular treatment procedure, such as delivery of drugs or other agents to the treatment site. In particular, once the guidewire 10, has been inserted to the desired treatment site, small quantities of drugs may be delivered directly to the treatment site through the central lumen. In order for such drug delivery to be effective, means must be provided in the spring member 30, for the exit of drugs from the central lumen. In particular, it may be desirable to leave the spring member 30, entirely without the encapsulation material 40. Therefore, drugs delivered through the central lumen may simply flow out between the wire filaments making up the spring member 30. In a preferred embodiment, the spring member 30, is partially encapsulated in order to provide specific means for delivery of the drugs. In particular, holes may be provided through the encapsulating material 40, to allow the drugs to flow out of the central lumen. Any arrangement of holes may be used, such as a single or multiple large holes for discrete or bolus delivery of the drugs to a specific treatment site; or series of small holes to provide a misting effect or delivery to a longer treatment area.

Therefore, the device according to the present invention is very advantageous in providing the necessary flexibility to travel the tortious path of the vascular system or body passages of the patient. In addition, the device according to the present invention, allows the transmission of torque along its entire length, and

SUBSTITUTE SHEET especially along the length of the spring member. Such torsional stability gives the device greater maneuverability and pushability for transversing the vascular system or body passages of the patient.

The foregoing has been a description of certain preferred embodiments of the present invention, but is not intended to limit the invention in any way. Rather, many modifications, variations and changes in details may be made within the scope of the present invention.

SUBSTITUTE S ET

Claims

What is claimed is :

1. A guidewire comprising : a spring member made up of wire filaments at the distal end of said guidewire; and a tubular member attached to the proximal end of said spring member; wherein said spring member and said tubular member are attached in such a manner as to provide a smooth, continuous transition from one to the other; wherein each of said spring member and said tubular member have a generally cylindrical cross section, and the interior surfaces of said spring member and said tubular member constitute a continuous central lumen running the entire length of said guidewire; and wherein said spring member is treated in such a manner as to allow transmission of torque from the proximal end to the distal end of said guidewire.

2. A guidewire according to claim 1, wherein said wire filaments making up said spring member are braided.

3. A guidewire according to claim 2, wherein said wire filaments of said spring member have a one-over-one- under or a two-over-two-under braid configuration, with any suitable number of plaits per inch.

4. A guidewire according to claim 1, wherein said wire filaments of said spring member are concentric coils of flat metal bands, and said coils are wound in such a manner that the winding is reversed for each adjacent coil.

SUBSTITUTE SHEET

5. A guidewire according to claim 4, wherein there are two coils of flat metal bands making up said spring member.

6. A guidewire according to claim 4, wherein there are three or more coils of flat metal bands making up said spring member.

7. A guidewire according to claim 1, wherein said tubular member is formed from stainless steel, has an outside diameter of .010 to .028 inch, and has an inside diameter of about .004 to .025 inch.

8. A guidewire according to claim 7, wherein said tubular member has an outside diameter of about .018 inch, and an inside diameter of about .010 inch.

9. A guidewire according to claim 1, wherein the outer surface of said tubular member is coated with a thin layer of a lubricious material.

10. A guidewire according to claim 1, wherein said spring member is formed from stainless steel or a strong polymeric fiber and has a length up to about fifty percent of the total length of said guidewire.

11. A guidewire according to claim 10, wherein said spring member is about 30 cm in length.

12. A guidewire according to claim 1, wherein said wire filaments making up said spring member have a round cross-section, with a diameter of about .001 to .005 inch.

SUBSTITUTE SHEET

13. A guidewire according to claim 12, wherein said wire filaments have a diameter of about .003 inch.

14. A guidewire according to claim 1, wherein said spring member is encapsulated with an encapsulating material.

15. A guidewire according to claim 14, wherein said encapsulating material is a soft, flexible polymeric substance.

16. A guidewire according to claim 1, wherein said spring member is treated so as to provide radiopacity.

17. A guidewire according to claim 16, wherein radiopacity is provided by substituting a short segment of a radiodense material for a section of said wire filaments of said spring member.

18. A guidewire according to claim 17, wherein said radiodense metal is platinum, gold or tantalum.

19. A guidewire according to claim 17, wherein a portion of said spring member is encapsulated with a polymer which has been filled with a radiopaque material.

20. A guidewire according to claim 1, wherein said central lumen allows the passage of discrete devices through said guidewire; said discrete devices being any of a movable tapered corewire, an optical fiber, or an electrical lead.

SUBSTITUTE SHEET

21. A guidewire according to claim 20, wherein said discrete device is a movable tapered corewire which may be used to control the flexibility and shape of said spring member.

22. A guidewire according to claim 1, wherein said central lumen allows drugs to be administered through said guidewire.

23. A guidewire according to claim 22, wherein said spring member is at least partially encapsulated with an encapsulating material.

24. A guidewire according to claim 23, wherein said encapsulating material is a soft, flexible polymeric substance.

25. A guidewire according to claim 23, wherein said encapsulating material has at least one hole therethrough, communicating with a portion of said central lumen within said spring member, said at least one hole allowing said drugs or other agents to pass from said central lumen to the exterior of said guidewire.

26. A guidewire according to claim 25, wherein said encapsulating material has one hole which allows said drugs or other agents to be delivered to a discrete location.

27. A guidewire according to claim 25, wherein said encapsulating material has a series of holes which allows said drugs or other agents to be delivered over a general treatment area.

S

28. A guidewire according to claim 1, wherein said guidewire is used in an angxcplasty procedure.

29. A guidewire according to claim 28, wherein said guidewire is used to guide a balloon catheter to an area of lesion or blockage of an artery.

30. A guidewire according to claim 1, wherein said guidewire is used in a neuroradiology procedure.

31. A guidewire according to claim 30, wherein said guidewire is used to guide a catheter to a blood vessel which requires opening or closing.

32. A guidewire according to claim 30, wherein said guidewire is used to deliver agents or devices for opening or closing a blood vessel.

33. A guidewire according to claim 1, wherein said guidewire is used to guide a catheter for use in the general vascular system.

34. A guidewire according to claim 1, wherein said guidewire is used to guide a general use catheter.

SUBSTITUTE SHEE^"

35. A method for guiding a catheter to a treatment location within a living being, said method comprising: inserting a guidewire into said living being to a position within said treatment location; and threading said catheter over said guidewire and pushing said catheter along said guidewire until said catheter is properly positioned within said treatment location; wherein said guidewire comprises: a spring member made up of wire filaments at the distal end of said guidewire; and a tubular member attached to the proximal end of said spring member; wherein said spring member and said tubular member are attached in such a manner as to provide a smooth, continuous transition from one to the other; wherein each of said spring member and said tubular member have a generally cylindrical cross section, and the interior surfaces of said spring member and said tubular member constitute a continuous central lumen running the entire length of said guidewire; and wherein said spring member is treated in such a manner as to allow transmission of torque from the proximal end to the distal end of said guidewire.

SUBSTITUTE S

36. A method of delivering drugs or other agents to a treatment location within a living being, said method comprising: inserting a guidewire into said living being to a position within said treatment location; and delivering said drugs or other agents through said guidewire to said treatment location; wherein said guidewire comprises: a spring member made up of wire filaments at the distal end of said guidewire; and a tubular member attached to the proximal end of said spring member; wherein said spring member and said tubular member are attached in such a manner as to provide a smooth, continuous transition from one to the other; wherein each of said spring member and said tubular member have a generally cylindrical cross section, and the interior surfaces of said spring member and said tubular member constitute a continuous central lumen running the entire length of said guidewire; and wherein said spring member is treated in such a manner as to allow transmission of torque from the proximal end to the distal end of said guidewire.

SUBSTITUTE SHEET