Guidewire with an intermediate variable stiffness section

Details Guidewire with an intermediate variable stiffness section Guidewire with an intermediate variable stiffness section

2000-12-21

2003-02-25

Mancene, Gene (Department: 3747)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06524301

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to the field of intraluminal guide wires for advancing catheters such as stent delivery catheters, balloon dilatation catheters, atherectomy catheters and the like, within body lumens.
In a typical percutaneous coronary procedure, a guiding catheter having a preformed distal tip is percutaneously introduced into a patient's peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. For rapid exchange type catheters having a short guidewire receiving lumen within their distal extremities, a guide wire is first advanced by itself through the guiding catheter until the distal tip of the guide wire extends beyond the arterial location where the procedure is to be performed. Then a rapid exchange type catheter, such as described in U.S. Pat. No. 5,061,395 (Yock), is mounted onto the proximal portion of the guide wire which extends out of the proximal end of the guiding catheter which extends outside of the patient. Over the wire type catheters (OTW) have guidewire lumens which extend through the entire length of the catheter and with these types of catheters the guidewire and OTW catheters are advanced together within the guiding catheter until the distal ends thereof are at the distal end of the guiding catheter. The guidewire is then advanced out the distal end of the guiding catheter into the body lumen until the distal end of the guidewire is disposed beyond the procedure site.
In either case, once the guidewire is in place with the distal end distal to the procedure site, the intravascular catheter is then advanced over the guide wire, while the position of the guide wire is fixed, until the operative means on the catheter is disposed within the arterial location where the procedure is to be performed. After the procedure, the intravascular catheter may be withdrawn from the patient or the guide wire repositioned within the coronary anatomy for an additional procedure.
Further details of guide wires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are hereby incorporated herein in their entirety by reference thereto.
Conventional guide wires for angioplasty, stent delivery, atherectomy and other intravascular procedures usually have an elongate core member with relatively stiff proximal section and a flexible distal section with one or more distally tapered segments. A flexible body member, such as a helical coil or a tubular body of polymeric material, is typically disposed about the distal section of the core member. A shapeable member, which may be the distal extremity of the core member or a separate shapeable ribbon which is secured to the distal extremity of the core member extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding, or an adhesive in the case of polymeric flexible bodies which forms a rounded distal tip. The distal section is flexible and will not damage or perforate the vessel or body lumen through which it is advanced and the portion behind the distal tip is increasingly stiff which better supports a balloon catheter or similar device.
The advancement of an intraluminal catheter over a guide wire may be difficult where intravascular tortuosity, calcification, noncompliance, fibrotic plaque, previously deployed stents or other obstructions are present proximal to the target site or lesion. With the use of conventional guide wires having a core member of longitudinally constant stiffness in their proximal sections, the contact of the guidewire with vessel walls, e.g., adjacent a bend in the vessel, may cause the advancing catheter or other device to impinge or “catch” upon such an obstruction, impeding advancement.
The use of a guide wire of lower stiffness may lessen the friction force of the catheter upon the vessel wall and obstruction, but the reduced stiffness may lead to insufficient “pushability” and prolapse of the guide wire.
One useful approach to easing advancement of the catheter through proximal obstructions is the use of a guidewire commonly called a “wiggle wire” which has a core length that is formed into a plurality of “kinks” or undulations where the core length has an S-shape. See for example U.S. Pat. No. 5,007,434 (Doyle et al.) assigned to the present assignee which is incorporated by reference herein in its entirety. When an obstruction is encountered, the portion of the “wiggle wire” guidewire having the undulating or S-shaped core segment is alternately advanced and retracted through the catheter distal tip, causing the tip to “nod” laterally from side-to-side while the catheter is pushed through the vessel, so as to avoid and bypass the obstruction on the vessel wall. However, the guidewire with the kinked or undulating shape generally results in reduced steerability and control for the guidewire, and may require a larger guidewire lumen in the catheter to accommodate the undulated shape which increases the catheter profile.
SUMMARY OF INVENTION
The present invention is directed to an guide wire for the deployment of an elongated medical device within a patient's body lumen. The guidewire includes an elongated core member with a proximal core section, a distal core section more flexible than the proximal core section and a flexible body such as a coil or polymeric tube disposed about and secured to the distal core section. The core member includes an intermediate core section disposed between the proximal core section and the distal core section, which has a plurality of segments or sub-portions which alternate between relatively stiff and relatively flexible contiguous segments or sub-portions along a length of the intermediate core section. A flexible segment between two adjacent stiff segments allow the intermediate core section to articulate when advancing through a tortuous body lumen so that the intermediate section bends discontinuously into discrete portions.
The segments of the intermediate core section are disposed in a linear arrangement and alternate between being relatively rigid or stiff and being relatively non-rigid or flexible, along a significant length of the intermediate core section. Thus, each flexible segment is bounded on each end by a stiff segment to allow articulation between the two stiff segments. When the intermediate core section of the guide wire is advanced into a curved portion or bend in the vessel, the intermediate section as a whole bends to conform overall with the vessel curvature. The flexible intermediate segments are substantially less resistant to bending than the stiff intermediate segments; so as a result most of the bending occurs in the flexible core segments, with the relatively stiff intermediate segments remaining relatively straight or otherwise undeformed and articulating about the flexible segments.
When a catheter is advanced through a body lumen over a conventional guidewire and the leading edge of the catheter engages an obstruction in the wall of the vessel, such as a strut from a previously deployed stent, a ledge of fibrotic plaque, or the like, further advancement of the catheter is impeded. However, utilization of a guide wire having features of the invention will allow the distal tip of the catheter to oscillate o r nod. The oscillation or “nod” motion of the catheter's distal tip causes the distal tip to periodically reduce or eliminate contact with the obstruction while the catheter is pushed through the vessel. To provide the oscillation of the catheter's distal tip, the intermediate core section lies adjacent and across the obstruction. Either the catheter or the guide wire, or both, may be moved longitudinally to an advanced or a

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