Nested stent

Details Nested stent Nested stent

1999-03-17

2001-11-20

Isabella, David J. (Department: 3738)

Prosthesis (i.e., artificial body members), parts thereof, or ai

Arterial prosthesis

Stent in combination with graft

C623S001220

Reexamination Certificate

active

06319277

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to implantable intraluminal stents and more particularly, the present invention relates to an improved high strength intraluminal stent having increased wire density.
BACKGROUND OF THE INVENTION
It is well known to employ endoprostheses for the treatment of diseases of various body vessels. Intraluminal devices of this type are commonly referred to as stents. These devices are typically intraluminally implanted by use of a catheter into various body organs such as the vascular system, the bile tract and the urogenital tract. Many of the stents are radially compressible and expandable so that they may be easily inserted through the lumen in a collapsed or unexpanded state. Some stent designs are generally flexible so they can be easily maneuvered through the various body vessels for deployment. Once in position, the stent may be deployed by allowing the stent to expand to its uncompressed state or by expanding the stent by use of a catheter balloon.
As stents are normally employed to hold open an otherwise blocked, constricted or occluded lumen; a stent must exhibit a relatively high degree of radial or hoop strength in its expanded state. The need for such high strength stents is especially seen in stents used in the urogenital or bile tracts where disease or growth adjacent the lumen may exert an external compressive force thereon which would tend to close the lumen.
One particular form of stent currently being used is a wire stent. Stents of this type are formed by single or multiple strands of wire which may be formed into a shape such as a mesh coil, helix or the like which is flexible and readily expandable. The spaces between the coiled wire permit such flexibility and expansion. However, in certain situations, such as when the stent is employed in the urogenital or bile tract, it is also desirable to inhibit tissue ingrowth through the stent. Such ingrowth through the stent could have a tendency to reclose or occlude the open lumen. The open spaces between the wires forming the stent, while facilitating flexibility and expansion, have a tendency to allow such undesirable tissue ingrowth.
Attempts have been made to provide a stent which has less open space and more solid wire. U.S. Pat. No. 5,133,732 shows a wire stent where the wire forming the stent is overlapped during formation to provide less open space. However such overlapping wire increases the diameter of the stent and has a tendency to reduce flexibility and make implantation more difficult. It is therefore desirable to provide a wire stent which exhibits high compressive strength and full flexibility without allowing extensive ingrowth therethrough.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an intraluminal stent which exhibits high compressive strength and is resistive to tissue ingrowth.
It is a further object of the present invention to provide a flexible wire stent having high compressive strength and maximum wire density to inhibit tissue ingrowth.
In the efficient attainment of these and other objects, the present invention provides an intraluminal stent including a generally elongate tubular body formed of a wound wire. The wire forming the stent is formed into successively shaped waves, the waves being helically wound along the length of the tube. The longitudinal spacing between the helical windings of the tube is formed to be less than twice the amplitude of the waves thereby resulting in a dense wire configuration.
As more particularly shown by way of the preferred embodiment herein, an intraluminal wire stent includes longitudinally adjacent waves being nested along the length of the tubular body. The peaks or apices of the longitudinally nested waves are linerally aligned. Further, the intraluminal stent so constructed would have a percentage of open surface area in relationship to the total surface area of the stent which is less than 30% in the closed state, resulting in less open area upon expansion which would inhibit tissue ingrowth.


REFERENCES:
patent: 5643312 (1997-07-01), Fischell et al.
patent: 5876432 (1999-03-01), Lau et al.
patent: 5879370 (1999-03-01), Fischell et al.

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