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GUIDEWIRE WITH DEFLECTABLE TIP
HAVING IMPROVED FLEXIBILITY
CROSS-REFERENCE TO RELATED
This patent application is a continuation-in-part of U.S. patent application Ser. No. 10/691,823, filedonOct. 23,2003, entitled, "Guidewire With Deflectable Tip Having Improved Torque Characteristics," which is a continuation-in-part of 10 U.S. patent application Ser. No. 10/224,168, filed onAug. 20, 2002, entitled, "Guidewire With Deflectable Tip," now issued as U.S. Pat. No. 7,128,718, which is a nonprovisional patent application of U.S. patent application Ser. No. 60/366,739, filed on Mar. 22, 2002, entitled, "Deflection Wire Concept." 15
BACKGROUND OF THE INVENTION
Hammerslag, et al., U.S. Pat. No. 5,203,772 to Gary R. Hammerslag, et al., U.S. Pat. No. 6,146,338 to Kenneth C. Gardeski, et al., U.S. Pat. No. 6,126,649 to Robert A. VanTassel, et al., U.S. Pat. No. 6,059,739 to James C. Baumann and U.S. Pat. No. 5,372,587 to Julius G. Hammerslag, et al. U.S. Pat. No. 4,940,062 to Hilary J. Hampton, et al., discloses a balloon catheter having a steerable tip section. All of the above-identified patents are incorporated herein by reference.
While each of the latter group of patents disclose guidewires having some degree of steerability, there is a need to have a guidewire with very precise steering in a guidewire of a very small diameter which is suitable for the purposes described above. More particularly, there is an important need for a very small diameter guidewire having improved torque characteristics which includes a distal tip which may be deflected very precisely in either of two directions to enhance steerability.
1. Field of the Invention
The present invention relates to a steerable guidewire and 20 more particularly to a steerable guidewire having a tip which may be very precisely steered or deflected. The guidewire is particularly suitable for use in conjunction with the insertion of a catheter into a vessel of the body, or alternatively, the guidewire may be used to open obstructions within a vessel. 25
2. Description of the Prior Art
For many years guidewires have included a core wire with the distal end being tapered and with a coil spring mounted on the tapered distal end. These guidewires have been used to facilitate the insertion of a catheter into a vessel of the body. 30 Generally, the guidewire is inserted into a vessel, a catheter is inserted over the guidewire and the catheter is then moved through the vessel until the distal end of the catheter is positioned at a desired location. The guidewire is then retracted from the catheter and the catheter is left in the vessel. Alter- 35 natively, the guidewire may be first inserted into the catheter with the distal portion of the guidewire extending beyond the distal end of the catheter. This assembly is then inserted into a vessel with the distal tip of the guidewire being used to facilitate movement of the guidewire and catheter through the 40 vessel. Again, when the distal tip of the catheter has been placed in a desired location, the guidewire may be retracted thereby leaving the catheter in place within the vessel.
Another common application for guidewires is that of using the distal tip of the guidewire for removing an obstruc- 45 tion within a vessel. Often times this procedure is accomplished by inserting the guidewire within a vessel, moving the distal tip of the guidewire into contact with the obstruction and then very gently tapping the distal tip of the guidewire against the obstruction until the guidewire passes through the 50 obstruction. Alternatively, various types of devices may be placed on the distal end of a guidewire for actively opening an obstruction within the vessel. Examples of such devices which may be placed on the end of the guidewires in order to open an obstruction are disclosed in the following United 55 States patents to Robert C. Stevens: U.S. Pat. Nos. 5,116,350; 5,078,722; 4,936,845; 4,923,462; and 4,854,325.
While most guidewires used today do not include a mechanism for deflecting or steering the tip of the guidewire, it is very desirable to provide tip steering in order to facilitate 60 movement of the guidewire through the tortuous vessels of the body. There are many patents directed toward different mechanisms for deflecting the distal tip of a guidewire in order to steer the guidewire. Examples of such guidewires are disclosed in the following patents: U.S. Pat. No. 4,815,478 to 65 Maurice Buchbinder, et al., U.S. Pat. No. 4,813,434 to Maurice Buchbinder, et al., U.S. Pat. No. 5,037,391 to Julius G.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a very small diameter steerable guidewire having a deflectable tip which includes an elongated flexible tubing, a flexible helical coil attached to the distal portion of the flexible tubing, an elongated deflection member which is slidably disposed within the tubing and within the helical coil. The deflection member is of a cylindrical configuration and the distal portion has a flattened side which tapers from a position proximal to the distal end of the deflection member to a position at about the distal end of the deflection member. Preferably, the distal portion also has a second flattened side on the opposite side of the deflection member which also tapers from a position proximal to the distal end to a position at about the distal end. More preferably, the one flattened side or both flattened sides of the distal portion taper substantially uniformally over the length of the tapered portion(s). In addition, a retaining ribbon is attached to the distal end of the flexible tubing and is oriented to extend in a plane which is generally parallel to the plane of the flattened side of the deflection member. An attachment member which may take the form of a rounded bead, preferably formed from epoxy, is bonded to the distal end of the helical coil, the distal end of the deflection member and the distal end of the retaining ribbon so that longitudinal movement of the deflection member causes the distal end of the helical coil to be deflected. With the flattened side or sides of the distal tip of the deflection member, the guidewire can be easily deflected in opposite directions but in a single plane, i.e., there is substantially no twisting of the guidewire upon deflection.
In accordance with another aspect of the present invention, the distal tip of the deflection member is preferably preshaped into a curved configuration to thereby cause the flexible helical coil to be biased into a normally curved shape.
In accordance with a further aspect of the present invention, the distal portion of the deflection member engages the attachment member, or rounded bead, at a location offset from the center of the attachment member, and the distal portion of the retaining ribbon engages the attachment member at a location offset from the center of the attachment member. Preferably, the retaining ribbon engages the attachment member at a location offset from the center portion of the attachment member in the opposite direction from the offset location of the deflection member.
In accordance with still another aspect of the present invention, the distal tip of the deflection member and the retaining ribbon are connected to each other within the attachment member. Preferably these two elements are formed as a single