FORM 2

THE PATENTS ACT  1970
(39 OF 1970)

COMPLETE SPECIFICATION
(Section 10  Rule 13)

TITLE
STENT DESIGN CONFIGURATIONS

Name : M/s. Relisys Medical Devices Limited

Nationality : Indian Company

Address : Survey No.312  Pocharam Road 
Mangalpally Village  Ibrahimpatnam Mandal 
Ranga Reddy District  Andhra Pradesh  INDIA

The following specification particularly describes the invention and the manner in which it is to be performed:-
FIELD OF THE INVENTION

The present disclosure relates to stents for use in intraluminal applications. More particularly  this invention pertains to a stent design configurations.

BACKGROUND OF THE INVENTION

Stents are widely used for numerous applications where the stent is placed in the lumen of a patient and expanded. Such stents may be used in coronary or other vasculature  as well as other body lumens.

Commonly  stents are cylindrical members. The stents expand from reduced diameters to enlarged diameters. Frequently  such stents are placed on a balloon catheter with the stent in the reduced-diameter state. So placed  the stent is advanced on the catheter to a placement site. At the site  the balloon is inflated to expand the stent to the enlarged diameter. The balloon is deflated and removed  leaving the enlarged diameter stent in place. So used  such stents are used to expand occluded sites within a patient""s vasculature or other lumen.

Examples of prior art stents are numerous. For example  U.S. Pat. No. 5 695 516 to Fischell teaches a stent with a cell having a butterfly shape when the stent is in a reduced-diameter state. Upon expansion of the stent  the cell assumes a hexagonal shape or U.S. Pat. No. 5 449 373 to Pinchasik et al. teaches a stent with at least two rigid segments joined by a flex-ible connector.

Stents are tubular  usually cylindrical devices which hold open a segment of blood vessel or other body lumen. They also are suitable to support and hold back a dissected arterial lining that can occlude the lumen. At present  numerous models of stents art marketed throughout the world. While some of these stents are flexible and have the appropriate strength and ri-gidity needed to hold open a lumen such as a coronary artery  each stent design typically represents a compromise between the stent""s flexibility and its radial strength. What has been needed  and heretofore unavailable  is a stent which has a high degree of flexibility so that it can be advanced through tortuous lumen and readily expanded  and yet have the mechanical strength to hold open the lumen or artery into which it is implanted and provide enough stiffness to prevent catheter rotation. Also needed is a stent that provides adequate vessel wall coverage  permits a large expansion range and offers more conformability.

Based on the above  it is apparent that there remains the need of improving the existing stents and developing alternative designs and methods for inhibiting smooth muscle cell proliferation to reduce in-stent restenosis.

SUMMARY OF THE INVENTION

In one aspect  the present invention is directed to a surgical stent which has a specific geo-metric design configuration. The surgical stent has a generally cylindrical stent frame confi-gured for implanting into a body lumen  and the stent frame has external surface having thereon a micro geometric patterned surface comprising a multiplicity of microgrooves distri-buted in a predetermined pattern. Preferably  the micro geometric pattern surface comprises open loop cell which repeats in rows depending on length required  wherein the cells are connected with non-flex connectors from peak to valley pattern.

An embodiment of the invention has rows connected with non-flex connection at least one extremities and some embodiments preferably at the mid segment.

The surgical stent of the present invention is a coronary artery stent. It can also be an eso-phagus stent  or an ureter stent.

Typically  a balloon expandable stent is made from a stainless steel alloy or similar material. The cylindrical rings of the stent are plastically deformed when expanded by the balloon. The cylindrical rings of the stent can expand radially outwardly without a balloon when the stent is formed from a material such as Stainless Steel (316LVM) and Cobalt Alloy (L605). These so-called “self-expanding” stents expand upon application of a temperature change or when a stress is relieved  as in the case of a pseudo-elastic phase change.

The number of peaks  valleys and non-flex connectors can be varied as the application re-quires. When using non-flex connectors  the connectors typically does not expand  but the connectors do continue to provide flexibility and to also provide scaffolding function to assist in holding open the artery. Further  because the connectors do not expand or stretch when the stent is radially expanded  the overall length of the stent is substantially the same in the unexpanded and expanded configurations. In other words  the stent will not appreciably shorten upon expansion.

The stent can be formed from a tube by laser cutting the pattern of non-flex connectors and peak to valley pattern in the tube. The stent also may be formed by laser cutting a flat metal sheet in the pattern of the non-flex connectors and peak to valley pattern  and then rolling the pattern into the shape of the tubular stent and providing a longitudinal weld to form the stent.

In any case  by employing any of a number of the referenced features (alone or in combina-tion)  stents/implants and delivery guides offering desirable functionality according to the present invention are amenable to scaling to sizes and offering functionality not previously achieved. Consequently  the systems may be used in lieu of a guide wire  such as in a "guide wireless" delivery approach. Still further  rather than providing an "over-the-wire" delivery system as referenced above  the present systems may be regarded as "on-the-wire" delivery systems  since - in effect - delivery is accomplished by a system in which the stent is carried by a delivery guide occupying a catheter lumen that would commonly otherwise be used to accommodate a guide wire.

Whether used in such a manner or otherwise (such as by configuring the subject systems for treating larger peripheral vessels)  the present invention includes systems comprising any combination of the features described herein. Methodology described in association with the devices disclosed also forms part of the invention. Such methodology may include that asso-ciated with completing an angioplasty  bridging an aneurysm  deploying radially-expandable anchors for pacing leads or an embolic filter  or placement of prosthesis within neurovascula-ture  an organ selected from the kidney and liver  within reproductive anatomy such as the vasdeferens and fallopian tubes or for other applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more fully hereinafter with reference to the ac-companying drawings  in which preferred embodiments of the invention are shown. This in-vention may  however  be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather  these embodiments are provided so that this disclosure will be thorough and complete  and will fully convey the scope of the invention to those skilled in the art.

FIG. 1 shows a heart in which its vessels may be the subject of one or more angioplasty and stenting procedures;

FIG. 2 is a detailed view of a 5-cell peak to valley with non-flex connector configuration of the stent.

FIG. 3 is a detailed view of a 6 cell peak to valley with non-flex connector configuration of the stent.

FIG. 4 is a detailed view of a 6 cell peak to peak with non-flex connector configuration of the stent.

FIG.5 is a detailed view of an 8/10cell peak to peak with non-flex connector configuration of the stent.

DETAILED DESCRIPTION

Various exemplary embodiments of the invention are described below. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applica-ble aspects of the present invention. Various changes may be made to the invention de-scribed and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition  many modifications may be made to adapt a particular situation  material  composition of matter  process  process act(s) or step(s) to the objective(s)  spirit or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein.

In light of this framework  Fig. 1 shows a heart 2 in which its vessels may be the subject of one or more angioplasty and/or stenting procedures. To date  however  significant difficulty or impossibility is confronted in reaching smaller coronary arteries 4. If a stent and a delivery system could be provided for accessing such small vessels and other difficult anatomy  an additional 20 to 25% of coronary percutaneous procedures could be performed with such a system.

In one embodiment  the present invention provides a surgical stent which has micro geomet-ric patterned surface for inhibiting smooth muscle cell proliferation in the stent lumen.

In at least one embodiment  for example as shown in Fig. 2  the surgical stent 10 has a gen-erally cylindrical stent frame (not shown) configured for implanting into a body lumen  and the stent frame has external surface having thereon a micro geometric patterned surface com-prising a plurality of open loop cells distributed in a predetermined pattern. Preferably  the open loop cell pattern surface is an open loop 5-cell which repeats in rows depending on length required  wherein the cells are connected with plurality of non-flex connectors 12 to plurality of peaks 13 and valleys 14 portions.

In some embodiments  according to the Fig. 3  the surgical stent 20 has generally cylindrical stent frame (not shown) configured for implanting into a body lumen  and the stent frame has external surface having thereon a micro geometric patterned surface comprising a plurality of open loop cells distributed in a predetermined pattern. Preferably  the open loop cell pattern is an open loop 6- cell which will repeat in rows depending on length required. The Length of the stent varies from 8mm to 40mm and the outer diameter of the stent is 1.6mm.The Cells are connected with Non-flex connectors 21 from Peak 22 to valley 23 portions. Here the first and last row is connected with non-flex connector in regular intervals and other rows are connected at two extremities and at mid segment.

In some embodiments  according to the Fig. 4  the surgical stent 30 has generally cylindrical stent frame (not shown) configured for implanting into a body lumen  and the stent frame has external surface having thereon a micro geometric patterned surface comprising a plurality of open loop cells distributed in a predetermined pattern. Preferably  the open loop cell is an open loop 8 cell which repeats in rows depending on length required. The Length of the stent varies from 8mm to 40mm and the outer diameter of the stent is 1.6mm.The Cells are con-nected with Non-flex connectors from Peak to Peak portions. Here the first and last row is connected with non-flex connector in regular intervals and other rows are connected at two extremities and at mid segment.

In some embodiments  according to the Fig. 5  the surgical stent 40 has generally cylindrical stent frame 41 configured for implanting into a body lumen  and the stent frame has external surface having thereon a micro geometric patterned surface comprising a plurality of open loop cell distributed in a predetermined pattern. Preferably  the open loop cell is an open loop 6/8/10 cell which will repeat in rows depending on length required. The Length of the stent varies from 8mm to 40mm and the outer diameter of the stent is 1.6mm.The Cells are con-nected with Non-flex connectors from Peak to Peak portions. Here the first and last row is connected with non-flex connector in regular intervals and other alternate rows are connected by Non-flex connectors and flex connectors at two extremities and mid segment.

In some embodiments  the stent comprises nitinol. In some embodiments  the stent can comprise NiTi having variable properties along the length or circumference of the stent. In this way  localized areas of the stent can be more or less strong than other areas of the stent. Localized areas of the stent can undergo focal heat treatments to achieve the desired design.

In some embodiments  the stent may be made from any suitable biocompatible materials in-cluding one or more polymers  one or more metals or combinations of polymer(s) and metal(s). Examples of suitable materials include biodegradable materials that are also bio-compatible. By biodegradable is meant that a material will undergo breakdown or decompo-sition into harmless compounds as part of a normal biological process. Suitable biodegradable materials include polylactic acid  polyglycolic acid (PGA)  collagen or other connective proteins or natural materials  polycaprolactone  hylauric acid  adhesive proteins  co-polymers of these materials as well as composites and combinations thereof and combinations of other biodegradable polymers. Other polymers that may be used include polyester and polycar-bonate copolymers. Examples of suitable metals include  but are not limited to  stainless steel  titanium  tantalum  platinum  tungsten  gold and alloys of any of the above-mentioned metals. Examples of suitable alloys include platinum-iridium alloys  cobalt-chromium alloys including Elgiloy and Phynox  MP35N alloy and nickel-titanium alloys  for example  Nitinol.

In some embodiments  the stent comprises shape memory materials such as superelastic Nitinol or spring steel  or may be made of materials which are plastically deformable. In the case of shape memory materials  the stent may be provided with a memorized shape and then deformed to a reduced diameter shape. The stent may restore itself to its memorized shape upon being heated to a transition temperature and having any restraints removed therefrom.

In some embodiments  the stent is covered with a covering or membrane  for example ePTFE. The covering can also be placed on the inside of the stent  outside of the stent  in-between the open spaces of the stent structure  or combinations thereof.

The inventive stents may be created by methods including cutting or etching a design from a tubular stock  from a flat sheet which is cut or etched and which is subsequently rolled or from one or more interwoven wires or braids. Any other suitable technique which is known in the art or which is subsequently developed may also be used to manufacture the inventive stents disclosed herein.

In some embodiments at least a portion of the stent is configured to include one or more mechanisms for the delivery of a therapeutic agent. Often the agent will be in the form of a coating or other layer (or layers) of material placed on a surface region of the stent  which is adapted to be released at the site of the stent""s implantation or areas adjacent thereto.

A therapeutic agent may be a drug or other pharmaceutical product such as non-genetic agents  genetic agents  cellular material  etc. Some examples of suitable non-genetic thera-peutic agents include but are not limited to: anti-thrombogenic agents such as heparin  heparin derivatives  vascular cell growth promoters  growth factor inhibitors  Paclitaxel  etc. Where an agent includes a genetic therapeutic agent  such a genetic agent may include but is not limited to: DNA  RNA and their respective derivatives and/or components; hedgehog proteins  etc. Where a therapeutic agent includes cellular material  the cellular material may include but is not limited to: cells of human origin and/or non-human origin as well as their respective components and/or derivatives thereof Where the therapeutic agent includes a polymer agent  the polymer agent may be a polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS)  polyethylene oxide  silicone rubber and/or any other suitable substrate.

In some embodiments  the stent (or stents) can be used in a body lumen bifurcation  for ex-ample a vessel bifurcation.

In some embodiments  the stent can be used in an environment requiring a stent having flexibility  fatigue resistance  durability  and supplying requisite radial force. In some em-bodiments the stent is suited to be used in arteries of patient""s leg. In some embodiments  the stent is configured for use in the iliac  superficial femoral artery (SFA) or infrapopliteal ves-sels. In some embodiments  the stent is highly conformable  resistant to kink and fracture  and yet maintains stent radial force. In some embodiments  the proximal end portion has greater flexibility than the middle portion. In some embodiments  the distal end portion has greater flexibility than the middle portion. Moreover  in some embodiments  the flexibility of the stent transitions smoothly along the length of the stent such that the proximal end portion is less flexible than the middle portion and the distal end portion is less flexible than the middle portion. In some embodiments  the middle portion has uniform bending  uniform axial displacement performance  and uniform durability throughout the length of the middle portion.

While the present invention has been described in detail and pictorially shown in the accom-panying drawings  these should not be construed as limitations on the scope of the present invention  but rather as an exemplification of preferred embodiments thereof  It will be appar-ent  however  that various modifications and changes can be made within the spirit and the scope of this invention as described in the above specification and defined (n the appended claims and their legal equivalents.

CLAIMS
I/ We claim:

1. A stent having a generally cylindrical stent frame configured for implanting into a body lumen  said stent frame having an external surface; said external surface having thereon a micro geometric patterned surface comprising a plurality of open loop cells distrib-uted in a defined pattern which repeats in rows depending on length required  wherein said cells are connected with non-flex connectors in regular intervals from peak-to-peak or peak-to-valley portions.
2. The stent of claim 1  wherein said plurality of open loop cells having a substantially same width and a substantially same depth.
3. The stent of claim1  wherein said defined pattern of the open loop cell may be in a pre-determined fashion or alternative fashion.
4. The stent of claim 1  wherein length of the stent in a range from about 8 to about 40 mm.
5. The stent of claim 1  wherein outer diameter of the stent is preferably about 1.6mm.
6. The stent of claim 1 is a coronary artery stent  an esophagus stent  or an ureter stent.
7. The stent of claim 1 further comprising a biocompatible chemical compound on said stent frame; said biocompatible chemical compound being one selected from the group consisting of thrombosis inhibitor  cell growth inhibitor and combination thereof.
8. The stent of claim 7 further comprising coating said biocompatible chemical com-pound with a biodegradable polymer.

Dated this 12th day of January  2012.

ABSTRACT

The present invention relates to stent design configurations  wherein the stent has a cylindrical stent frame configured for implanting into a body lumen  said stent frame having an external surface; said external surface having thereon a micro geometric patterned surface comprising a plurality of open loop cells distributed in a pre-determined or alternative pattern which repeats in rows depending on length required  wherein said cells are connected with non non-flex connectors in regular intervals from peak-to-peak or peak-to-valley portions.