Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1998-06-17
2001-01-09
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
Reexamination Certificate
active
06171334
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to intravascular stents and more particularly pertains to improvements thereto that provide for increased coverage and greater expansion ratios without a compromise in strength.
Stents or expandable grafts are implanted in a variety of body lumens in an effort to maintain their patency. These devices are typically intraluminally implanted by use of a catheter which is inserted at an easily accessible location and then advanced to the deployment site. The stent is initially in a radially compressed or collapsed state to enable it to be maneuvered through the lumen. Once in position, the stent is deployed which, depending upon its configuration, is achieved either automatically or actively by the inflation of a balloon about which the stent is carried on the catheter.
As stents are normally employed to hold open an otherwise blocked, constricted or occluded lumen, a stent must exhibit sufficient radial or hoop strength in its expanded state to effectively counter the anticipated forces. Not only is it advantageous to distribute such loads over as much of the stent as possible but it also is most beneficial to distribute the load over as much lumen wall as possible. This will help minimize injury to the vessel wall. Also by minimizing the gaps between stent struts it is possible to prevent prolapse of the plaque between the struts into the lumen. As a consequence, it is desirable to maximize the coverage of the lumen wall by creating uniform, small gaps between the stent struts. It is, however, simultaneously necessary for the stent to be as small and compact as possible in its collapsed state in order to facilitate its advancement through the lumen. As large an expansion ratio as possible is therefore most desirable.
A number of very different approaches have been previously devised in an effort to address these various requirements. A popular approach calls for the stent to be constructed wholly of wire. The wire is bent, woven and/or coiled to define a generally cylindrical structure in a configuration that has the ability to undergo radial expansion. The use of wire has a number of disadvantages associated therewith including for example, a substantially constant cross-section which may cause greater or lesser than an ideal amount of material to be concentrated at certain locations along the stent. Additionally, wire has limitations with respect to the shapes it can be formed into thus limiting the expansion ratio, coverage area and strength that can ultimately be attained therewith. The welding of adjoining sections of wire together has also been previously employed to increase strength albeit with a substantial increase in manufacturing costs.
As an alternative to wire-based structures, stents have been constructed from tube stock. By selectively removing material from such tubular starting material, a desired degree of flexibility and expandability can be imparted to the structure. Chemical etching techniques as well as laser-cutting processes are utilized to remove material from the tube. Laser etching provides for a high degree of precision and accuracy with which very well defined patterns of material can be removed from the tube to conversely leave very precisely and accurately defined patterns of material in tact. The performance parameters of a function of the pattern in which material is removed form the tube stock. The selection of a particular pattern has a profound effect on the coverage area, expansion ratio and strength of the resulting stent.
While the tube-based stents offer many advantages over the wire-based designs, it is nonetheless desirable to improve upon such designs in an effort to further increase coverage area and expansion ratios while maintaining strength.
SUMMARY OF THE INVENTION
The present invention provides for an improved tube-based stent having an increased coverage area, expansion ratio and strength. The improvements arise with the selection of a precisely defined pattern of voids that are cut or etched into the tube stock. The pattern of material that remains to define the stent comprises a series of nested serpentine elements wherein selected apexes are interconnected to one another by bridging members. More particularly, each serpentine element extends circumferentially about the stent such that successive apexes of each element alternatively extend distally and proximally along the stent's surface. Adjacent serpentine elements are spaced about the stent wherein each element is nested in the adjacent elements such that the apexes of one element extend into the space between the apexes of the adjacent element. The serpentine elements are joined to one another along either all of their distal or all of their proximal apexes. Each of a particular element's apexes extending along its interconnected edge is alternatingly joined to the corresponding apexes of proximally and distally adjoining serpentine elements by bridging elements. By properly shaping the junction area between each bridging element and apex, stress risers are reduced or eliminated with a corresponding decrease in the potential for fracturing during expansion. By curving the transverse sections that extend between each of the apexes of a given clement, adjacent elements become more tightly packed. Coverage exceeding 20% with expansion ratios of 3.0 are thereby achievable, and expansion ratios exceeding 6.0 are also achievable. More importantly, this dense coverage is uniformly distributed throughout the stent.
These and other features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments which, taken in conjunction with the accompanying drawings, illustrate by way of example the principles of the invention.
REFERENCES:
patent: 3105492 (1963-10-01), Jeckel
patent: 3657744 (1972-04-01), Ersek
patent: 3993078 (1976-11-01), Bergentz et al.
patent: 4130904 (1978-12-01), Whalen
patent: 4140126 (1979-02-01), Choudhury
patent: 4159719 (1979-07-01), Haerr
patent: 4387952 (1983-06-01), Slusher
patent: 4503569 (1985-03-01), Dotter
patent: 4504354 (1985-03-01), George et al.
patent: 4512338 (1985-04-01), Balko et al.
patent: 4531933 (1985-07-01), Norton et al.
patent: 4553545 (1985-11-01), Maass et al.
patent: 4580568 (1986-04-01), Gianturco
patent: 4619246 (1986-10-01), Molgaard-Nielsen et al.
patent: 4649922 (1987-03-01), Wiktor
patent: 4650466 (1987-03-01), Luther
patent: 4655771 (1987-04-01), Wallsten
patent: 4681110 (1987-07-01), Wiktor
patent: 4706671 (1987-11-01), Weinrib
patent: 4733665 (1988-03-01), Palmaz
patent: 4739762 (1988-04-01), Palmaz
patent: 4740207 (1988-04-01), Kreamer
patent: 4762128 (1988-08-01), Rosenbluth
patent: 4767418 (1988-08-01), Deininger
patent: 4776337 (1988-10-01), Palmaz
patent: 4795458 (1989-01-01), Regan
patent: 4800882 (1989-01-01), Gianturco
patent: 4830003 (1989-05-01), Wolff et al.
patent: 4848343 (1989-07-01), Wallsten et al.
patent: 4856516 (1989-08-01), Hillstead
patent: 4870966 (1989-10-01), Dellon et al.
patent: 4877030 (1989-10-01), Beck et al.
patent: 4878906 (1989-11-01), Lindemann et al.
patent: 4886062 (1989-12-01), Wiktor
patent: 4892539 (1990-01-01), Koch
patent: 4893623 (1990-01-01), Rosenbluth
patent: 4907336 (1990-03-01), Gianturco
patent: 4913141 (1990-04-01), Hillstead
patent: 4922905 (1990-05-01), Strecker
patent: 4943346 (1990-07-01), Mattelin
patent: 4950227 (1990-08-01), Savin et al.
patent: 4963022 (1990-10-01), Sommargren
patent: 4969458 (1990-11-01), Wiktor
patent: 4969890 (1990-11-01), Sugita et al.
patent: 4986831 (1991-01-01), King et al.
patent: 4990155 (1991-02-01), Wilkoff
patent: 4994071 (1991-02-01), MacGregor
patent: 4998539 (1991-03-01), Delsanti
patent: 5002560 (1991-03-01), Machold et al.
patent: 5007926 (1991-04-01), Derbyshire
patent: 5015253 (1991-05-01), MacGregor
patent: 5019085 (1991-05-01), Hillstead
patent: 5019090 (1991-05-01), Pinchuk
patent: 5026377 (1991-06-01), Burton et al.
patent: 5034001 (1991-07-01), Garrison et al.
patent: 5035706 (1991-07-01),
Advanced Cardiovascular Systems Inc.
Fulwider Patton Lee & Utecht
Jackson Suzette J.
Willse David H.
LandOfFree
Expandable stent and method of use does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Expandable stent and method of use, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Expandable stent and method of use will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509677