Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Hollow or tubular part or organ
Reexamination Certificate
1997-02-26
2003-06-24
Thaler, Michael H. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Hollow or tubular part or organ
C623S001150, C623S001200, C604S008000
Reexamination Certificate
active
06582472
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to stents for use in supporting and maintaining an open lumen within a body passage or vessel and, more particularly, to stents configurable between large and small diameters.
2. Description of Related Art
Tubular prosthesis, which are commonly referred to as stents, are used to reinforce or strengthen body passages or vessels. Occluded, collapsed, or compromised body passages, such as blood vessels, esophagus, tracheas, gastrointestinal tracts, bile ducts, ureters, and urethras, can all benefit from stents. These body passages can become occluded, collapsed, or compromised from disease, trauma, or from specific surgical procedures upon the wall of the body passage.
Prior art stents typically comprise a length of plastic tubular material, having a number of side holes disposed along the length of the plastic tubular material. U.S. Pat. Nos. 4,913,683, 4,643,716, 5,282,784, 4,957,479, 4,931,037, and 5,364,340 describe stents generally constructed in this manner. Each of these stents basically comprises a fixed diameter and, therefore, is nonresponsive to the specific diameter of a vessel.
A prosthesis or stent capable of expanding to appropriate diameters, along the length of the stent, can provide advantages over fixed-diameter stents. Self-expanding stents are disclosed in U.S. Pat. Nos. 5,026,377 and 5,078,720, both issued to Burton et al.; U.S. Pat. No. 5,019,085 issued to Hillstead; U.S. Pat. No. 4,969,458 issued to Wicktor; and U.S. Pat. No. 5,041,126 issued to Gianturco. These self-expanding stents are typically held in a contracted condition during insertion into the body passage or vessel and, after being positioned within the passage or vessel, released to expand fully. The stents of Wicktor and Gianturco comprise coiled or looped wires, which are unable to contact the entire surface of the interior wall of the affected vessel.
The Hillstead stent incorporates a multiple-loop wire structure, which suffers from the same deficiencies associated with the Wicktor and Gianturco stents. U.S. Pat. No. 5,507,767, issued to Maeda et al., discloses a self-expanding stent that employs a plurality of straight stainless steel wire sections, separating a plurality of bends, that may be adjusted and set to fit a particular anatomy or condition. U.S. Pat. No. 5,476,505 issued to Limon discloses a coiled stent for introduction into a body passage at a first diameter and subsequent expansion within the body passage to a second diameter. This coiled stent relies on a procedure for holding a coil in a tightly-wound condition during insertion of the coiled stent. U.S. Pat. No. 5,409,019 issued to Wilk discloses a stent, which surrounds a balloon, so that the collapsed balloon, upon expansion, can expand the stent. U.S. Pat. Nos. 5,078,720 and 5,026,377 issued to Burton et al. describe a combination of a self-expanding braided stent and an instrument for deployment or retraction of the stent. The instrument for deployment or retraction of the stent includes a tubular sleeve, which surrounds and compresses the braided stent. This surrounding tubular structure, requires that an additional wall thickness, corresponding to a thickness of the tubular sleeve, be added T o the device during placement. Consequently, a shortcoming of the Burton et al. invention is that the placement of the device is the time when the lowest profile or smallest diameter is required.
A need remains in the prior art for a prosthesis or stent which can be placed accurately into a low-profile or small-diameter condition and which can expand in diameter to a predictable size with a predictable pressure applied to an interior surface of the vessel wall. A need also exists in the prior art for a stent having a retention feature for maintaining the stent in a preferred position within the body passage. Additionally, a need exists in the prior art for a stent having a diameter, which is capable of responding and changing to the development of the lumen of the vessel or passage.
SUMMARY OF THE INVENTION
The stent of the present invention can be introduced into a body passage or vessel in a low profile or small diameter and, subsequently, expanded to a large diameter. The stent can be inserted into the body passage over a guidewire or small gauge catheter in the small diameter configuration. After the guidewire or small gauge catheter is removed, the stent is transformed into the large diameter configuration, which stimulates the reactive nature of the body passage to thereby develop or-maintain a patent lumen. The stent is able to provide maximum communication and flow of fluids from one surface of the stent to the other surface of the stent.
The stent of the present invention is formed of an elongate, flexible duct having a very thin wall and a preformed diameter, length, and shape. The stent is constructed of a woven tubular structure of multiple strands or elements. The woven tubular structure is thermally set to a predetermined diameter and length, so that the “at rest” or natural condition of the tubular structure is predictable. A retention or holding member can be formed at one or both of the ends of the stent. This retention member can be reduced in diameter for insertion into the body passage. The woven tubular structure provides a path for fluids to flow in and around the stent, while a patent lumen is being developed. The woven tubular structure allows the stent to be extended or stretched over a guidewire or other noncompressive member, to thereby reduce the diameter of the stent for insertion of the stent into a body passage.
According to one aspect of the present invention, a stent for use in a body passage includes an expandable tube having a proximal tube end, a distal tube end, and a lumen extending from the proximal tube end to the distal tube end. The expandable tube is configurable between a large-diameter relaxed state and a small-diameter tension state. The proximal tube end and the distal tube end are separated by a predetermined distance when the expandable tube is in the large-diameter relaxed state, and the proximal tube end and the distal tube end are separated by a second distance, which is larger than the predetermined distance, when the expandable tube is in the small-diameter tension state. A retention member is integrally formed with the expandable tube and is located just proximally of the distal tube end. The retention member has a large-diameter relaxed shape and a small-diameter tension shape, and has a retention-member diameter, in the large-diameter relaxed shape, which is greater than an expandable tube diameter of the expandable tube, when the expandable tube is in the large-diameter relaxed state. The stent further includes activating means adapted for increasing a distance between the proximal tube end and the distal tube end, to thereby change the expandable tube from the large-diameter relaxed state to the small-diameter tension state. The activating means is also adapted for changing the retention member from the large-diameter relaxed shape to the small-diameter tension shape, by increasing a distance between the proximal tube end and the distal tube end. The activating means includes a compression tube, which is adapted for fitting within the lumen and for contacting the distal tube end. The compression tube is further adapted for applying a distal force onto the distal tube end when a proximal force is applied to the proximal tube end. Application of both the distal force and the proximal force changes the expandable tube from the large-diameter relaxed state to the small-diameter tension state, and removal of both the distal force and the proximal force changes the expandable tube from the small-diameter tension state to the large-diameter relaxed state.
According to another aspect of the present invention, a stent includes a stent body formed of a braided material and an enlarged diameter retention member adjacent to the stent body and integrally formed with the stent body of the bra
Applied Medical Resources Corporation
Myers Richard L.
Thaler Michael H.
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