Guidewire having substantially nickel-free high-nitrogen...

Details Guidewire having substantially nickel-free high-nitrogen... Guidewire having substantially nickel-free high-nitrogen...

1999-12-01

2001-12-04

Lacyk, John P. (Department: 3736)

Surgery

Diagnostic testing

Flexible catheter guide

Reexamination Certificate

active

06325766

ABSTRACT:

BACKGROUND
Metallic wires are widely used in medical procedures, a common example being the guidewires used to locate intravascular devices such as angioplasty catheters. Conventional guidewires for angioplasty and other vascular procedures usually comprise an elongated core member with one or more tapered sections near the distal end thereof and a flexible body such as a helical coil disposed about the distal portion of the core member. A shapable member, which may be the distal extremity of the core member or a separate shaping ribbon which is secured to the distal extremity of the core member extends through the flexible body and is secured to a rounded plug at the distal end of the flexible body. Torquing means can be provided on the proximal end of the core member to rotate, and thereby steer, the guidewire while it is being advanced through a patient's vascular system.
A major requirement for guidewires and other guiding members, whether comprising solid wire or tubular members, is that they have sufficient column strength to be pushed through a patient's vascular system or other body lumens without kinking. However, they must also be flexible enough to avoid damaging the blood vessel or other body lumen through which they are advanced. Commonly, guidewires are formed from two or more materials. A relatively short, distal section is configured to have superior handling characteristics and may be shaped to aid in selecting the desired branch of the vasculature. The relatively long proximal section, on the other hand, should have a high column strength and torquability as its primary characteristic. Accordingly, prior art guidewires have been made with stainless steel alloys such as 304V stainless steel which can have a composition which includes about 10% nickel. Such alloys can also be used for the entire length of the guidewire. Although widely used, some stainless steel alloys suffer from being relatively brittle and are subject to fatigue. In addition, the nickel content can be a drawback for patients who are sensitive to this element.
Accordingly, there is a need for guidewire materials having high tensile strength, while maintaining good ductility, fracture toughness and high number of fatigue cycles and strength. It can also be desireable to have a guidewire material with a low nickel content.
SUMMARY
The invention is directed to an elongated intracorporeal member, specifically an elongated guiding member comprising a core member formed from a substantially nickel-free high-nitrogen austenitic stainless steel alloy. Such an alloy can have improved tensile and fatigue strength compared to conventional nickel-containing alloys and improved ductility and fatigue strength as compared to conventional high tensile strength alloys. As used herein, the term high nitrogen substantially nickel-free austenitic stainless steel alloy refers to an alloy which can have a nitrogen content of about 0.90 to about 0.99 weight percent, specifically, about 0.96 to about 0.98 weight percent. Such an alloy can have a nickel content of up to about 0.4 weight percent, specifically, up to about 0.3 weight percent and more specifically up to about 0.2 weight percent. The invention is also directed to a guidewire having a shapeable member at a distal end formed from the substantially nickel-free high-nitrogen austenitic stainless steel alloy.


REFERENCES:
patent: 5769796 (1998-06-01), Palermo et al.
patent: 5879132 (1999-03-01), Usami et al.
patent: 5916166 (1999-06-01), Reiss et al.

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