Claims:WE CLAIM:
1. A stent system (10) comprising:
• a stent (100) including
• a proximal end (100a),
• a distal end (100b) and a predefined length extending there between, wherein the stent (100) includes flared ends at the proximal end (100a) and the distal end (100b), the stent (100) includes a closed-cell design having a plurality of rows of circumferential cells placed adjacent to each other, each of the plurality of rows having varying dimensions, each circumferential cell being formed by interconnecting multiple struts (102), one or more of the plurality of cells provided at the proximal end (100a) and the distal end (100b) include one or more extensions (102c);
• a plurality of coiled markers (106) placed on the extensions (102c) of the cells; and
• a delivery device (400) for delivering the stent, the delivery device (400) including a delivery wire (401) and a re-sheathing unit (407) mounted over the delivery wire (401) to which the stent (100) is coupled.
2. The stent system (10) of claim 1 wherein the diameter of the stent (100) ranges between 2.5mm to 6.0mm.
3. The stent system (10) of claim 1 wherein the diameter at the flared end of the proximal end (100a) and distal end (100b) ranges between 0.05mm to 0.95mm.
4. The stent system (10) of claim 1 wherein the stent (100) includes a length ranging from 10mm to 50mm.
5. The stent system (10) of claim 1 wherein the plurality of rows of circumferential cells includes a primary row (“X”), a secondary row (“Y”) and a tertiary row (“Z”).
6. The stent system (10) of claim 1 wherein the width of the struts (102) ranges from 0.05 to 0.15mm.
7. The stent system (10) of claim 1 wherein the coiled markers (106) are made of one of gold, silver, platinum, platinum-tungsten, platinum-iridium or combinations thereof.
8. The stent system (10) of claim 1 wherein the stent (100) includes a coating of one or more of anti-thrombogenic, or anti-inflammatory agents.
9. The stent system (10) of claim 1 wherein the coating includes one or more of phosphorylcholine, hyaluronic acid, heparin, bivalirudin, polyurethane, hirudin, streptokinase and urokinase.
10. The stent system (10) of claim 1 wherein the delivery device (400) includes an introducer sheath (403).
11. The stent system (10) of claim 1 wherein the re-sheathing unit (407) is a coil.
12. The stent system (10) of claim 1 wherein the delivery wire comprises a tapered delivery wire. , Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
INTRACRANIAL STENT SYSTEM
2. APPLICANTS:
MERIL LIFE SCIENCES PVT LTD, an Indian company, of the address Survey No. 135/139, Bilakhia House, Muktanand Marg, Chala, Vapi- 396191, Gujarat, India

3. The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
[1] The present invention relates to a medical device. More specifically, the present invention relates to a stent system for treating intracranial plaques and/or aneurysm.
BACKGROUND
[2] Intracranial stenosis and intracranial aneurysms correspond to one of the leading causes of stroke worldwide. Intracranial stenosis pertains to narrowing of major intracranial arteries due to the build-up of atherosclerotic plaque. Intracranial aneurysm also known as brain aneurysm is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning (bulging). The most detrimental stage of the aneurysm is reached when the balloon is burst (and/or ruptured) leading to stroke, massive internal bleeding, etc. One or more forms of anterior neurovascular aneurysms include ICA (Internal Carotid Artery) aneurysms, superior hypophysial artery aneurysms, ophthalmic artery aneurysms, anterior choroidal aneurysms, etc. The posterior neurovascular aneurysms may include anterior inferior cerebellar artery (AICA) aneurysms, posterior inferior cerebellar artery (PICA) aneurysms, superior cerebellar artery (SCA) aneurysms, etc.
[3] In order to treat intracranial stenosis, cerebral balloon angioplasty is performed. However, angioplasty is associated with significant risk of intimal dissection, thrombosis, recoiling and vessel rupture.
[4] Likewise, a lot of treatment strategies existing currently aim to cure intracranial aneurysms which include surgical clipping across artery which feeds the aneurysm, coiling method, glue, mesh stents flow diversion, etc. However, these methods exhibit various limitations due to size of the bulge (aneurysm) which requires various open brain surgical procedures for treatment. On the contrary, when the size of the bulge is smaller and the neck of the bulge is narrow, coils are placed with the help of microcatheters for it’s treatment. The use of said coils for the treatment of such aneurysms also exhibits various limitations. The said limitations include slippage of the coil from the neck of the aneurysm into the artery thereby blocking intracranial arteries.
[5] Further, endovascular treatment of wide-neck intracranial aneurysms (i.e., 04 mm or more) remains a technically challenging procedure due to the risk of coil protrusion into the parent artery and subsequent thrombus formation or parent vessel compromise.
[6] There are several techniques to coil wide-neck aneurysms, such as balloon/stent-assisted coiling, flow diversion etc. However, the currently existing intracranial stent designs have complications while bending over torturous regions of the vessels and kink after deployment. The conventional stents mostly include open-cell structure which does not allow re-sheathing of the stent if required and hence, such stents cannot be re-positioned once partially deployed. Further, the open cells tend to extend outwards at bend locations thereby increasing the chances of penetration of aneurysm.
[7] One such example is the prior art “US20150235569A1” titled “Device specific finite element models for simulating endovascular treatment” which discloses open cell structure. The Neuroform stent disclosed in the mentioned prior art features an open cell design and consists of eight sinusoidal crown segments. However, due to the open cell design as disclosed in the prior art, the chances of kinking of the stent is very high.
[8] Thus there is a need for a stent that can overcome the drawbacks of the prior arts.
SUMMARY
The present invention discloses a stent system. The stent system includes a stent mounted over the delivery device. The said stent may be implanted at the implantation site which includes an intracranial aneurysm or an intracranial vessel having a plaque. The stent of the present invention includes a closed cell design, predefined length with flared ends and plurality of rows of circumferential cells. The closed-cell design of the stent provides enhanced flexibility to the stent. Each circumferential cell being formed by interconnecting multiple struts. Additionally, one or more of the plurality of cells provided at the proximal end and distal end includes one or more extensions.
The said extensions include one or more coiled markers. The placement of the coiled markers on the extensions provides an efficient deployment of the stent inside the tortuous intracranial vessels. The delivery device for delivering the stent includes a delivery wire and a re-sheathing unit mounted over the delivery wire to which the stent is coupled. Further, the said stent may be coated with an anti-thrombogenic, or anti-inflammatory agents.
BRIEF DESCRIPTION OF DRAWINGS
[9] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[10] FIG. 1 illustrates a stent 100 in accordance with an embodiment of the present invention.
[11] FIG. 1a depicts the stent 100 with flared ends in accordance with an embodiment of the present invention.
[12] FIG. 2a depicts the primary, secondary and tertiary rows of cells of the stent 100 in accordance with an embodiment of the present invention.
[13] FIG. 2b shows different cells of the primary row of cells of the stent 100 in accordance with an embodiment of the present invention.
[14] FIGs. 2c and 2d depict cells of the “Y” and “Z” rows of the stent 100 in accordance with an embodiment of the present invention.
[15] FIG. 3 depicts the stent 100 with coiled markers 106 in accordance with an embodiment of the present invention.
[16] FIGs. 3a and 3b depict alternate embodiments of the stent 100 in accordance with an embodiment of the present invention.
[17] FIG. 4 depicts the delivery device 400 in accordance with an embodiment of the present invention.
[18] FIGs. 4a and 4b depict stents 100 implanted at the implantation sites in accordance with an embodiment of the present invention.
[19] FIGs. 5a and 5b illustrate stents disclosed in example 1 in accordance with an embodiment of the present invention.
[20] FIGs. 6a and 6b illustrate stents disclosed in example 2 in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[21] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like; Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[22] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[23] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[24] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and appended claims, or may be learned by the practice of embodiments as set forth hereinafter.
[25] The term ‘diameter’ in the following description corresponds to the outer diameter of the stent until and unless specified otherwise.
[26] In accordance with the present disclosure, an intracranial stent mounted over a delivery device (collectively referred to as a ‘stent system’) is disclosed. The intracranial stent of the present invention is deployed with the help of a delivery device at an implantation site. The implantation site in the present invention corresponds to, for example, an intracranial aneurysm or an intracranial vessel having a plaque. However, it should be noted that the present invention may also be used for other implantation sites such as peripheral vessels, carotid, renal blood vessels, etc.
[27] For treating intracranial aneurysms, the stent of the stent system in an embodiment of the present invention blocks the coil provided in the bulge from further movement. The stent is designed as a closed cell structure to provide effective placement of the stent in tortuous intracranial vessels thereby preventing kinking of the stent. Further, owing to the cell design of the present invention, the stent can be re-sheathed even after 60%-90% of deployment.
[28] The cells of the stent are majorly divided in three types of rows i.e. a primary, secondary and tertiary row of cells. The rows of the stent are connected together via a plurality of links, thus providing enhanced flexibility and crimped profile along with effective radial properties to the stent. The stent may be flared at both its ends (i.e. distal end and proximal end). Such flaring helps to effectively place the stent at the implantation site, say, intracranial arteries, thus minimizing the chances of its migration during deployment.
[29] Further, the proximal and distal ends of the stent include a plurality of radio-opaque markers having a coiled shaped configuration to provide better positioning of the stent during interventional procedure.
[30] Now referring to figures, FIG.1 shows the stent 100 of the present invention. The stent 100 is delivered at the implantation site with the help of the delivery device 400 (not shown in FIG.1). The stent 100 and the delivery device 400 of the present invention are collectively referred to as stent system 10. As provided above, the stent 100 of the present invention is employed to be used for treating intracranial stenosis and/or intracranial aneurysms.
[31] The stent 100 of the present invention may be made of any metallic material. The metallic material may include without limitation, stainless steel, titanium, cobalt-chromium, nitinol, etc. In an embodiment, the stent 100 is made of nitinol. The utilization of nitinol is preferred in the present invention due to its enhanced shape memory property and excellent biocompatibility. Owing to enhanced shape memory of nitinol, the stent 100 possesses greater flexibility and may be easily shaped as per the anatomy of the implantation site.
[32] Alternatively, the stent 100 may be fabricated from other degradable polymers such as poly-L-lactide-co-caprolactone (PLC), polycaprolactone (PCL), poly-DL-lactic acid (PDLLA), polyglycerolsebacate (PGS), poly L-lactide (PLLA), poly (glycolic acid) (PGA), poly L-lactide co-glycolic acid (PLGA) or a mixture thereof. The use of said degradable polymers minimizes the risk of stent restenosis.
[33] As depicted, the stent 100 includes a proximal end 100a and a distal end 100b. The stent 100 may include a uniform diameter from the proximal end 100a to the distal end 100b. The diameter of the stent 100 may range from 2.5mm to 6.0mm (depending upon the size of the vessel). In an embodiment, the diameter of the stent 100 is, one of, 3.5mm, 4.0mm or 4.5mm. Optionally, the proximal end 100a and the distal end 100b may be flared (as shown in FIG. 1a). In such a case, the diameters of the proximal end 100a and the distal end 100b are more than rest of the stent 100. The increase in diameter of the proximal end 100a and the distal end 100b may range between 0.05mm to 0.95mm, more preferably it ranges from 0.25mm to 0.75mm. The flared ends of the stent 100 provides stability to the stent 100 after deployment at the implantation site and reduce the chances of stent 100 migration.
[34] The distance between the proximal end 100a and the distal end 100b defines a length of the stent 100. In an embodiment, the length of the stent 100 may range from 10mm to 50mm and more preferably 15mm to 45mm. In the preferred embodiment, the length and diameter of the stent 100 is 18mm to 40mm and 3.5mm to 5.5mm respectively.
[35] The stent 100 of the present invention may include a plurality of cells being disposed in circumferential rows. Each cell may be formed by interconnecting multiple struts 102. Each of the cells may be connected with the adjacently placed cells using at least one link 104. Hence, a single link 104 connects two cells together.
[36] The links 104 may include any conventional structure known in the art. In an embodiment, the links 104 have a linear structure. The interconnections between each of the struts 102 of a cell with each other as well as the interconnections between each of the links 104 with the cells may be curved (having soft/curved edges).
[37] The width of the links 104 may be greater than the width of the struts 102 of the cell. Hence, owing to the increased width of the links 104 and curves provided in the stent 100, better flexibility and kink resistive nature of the stent 100 is ensured. The links 104 include a width lying in a range of 0.050mm to 0.250mm. In an embodiment, the width of the link 204 is 0.10mm.
[38] Further, the stent 100 includes at least three types of circumferential rows of cells. As clearly depicted in FIG. 2a, the stent 100 includes three rows i.e. a primary row “X”, a secondary row “Y” and a tertiary row “Z”. The above disclosed rows may be multiplied in a pre-defined number and order to form the stent 100. The presence of such types of rows constitutes a hybrid design of the stent 100 which helps to maintain required flexibility, radial strength and crimped profile. Further, such a design ensures minimal edge injury during the deployment and implantation of the stent 100. In an embodiment, the radial strength of the stent 100 is 100gf to 900gf while the crimped profile of the stent 100 is around 0.68mm.
[39] As shown in FIG. 2a, a primary row of cells “X” may be disposed at the distal end 100b and at the proximal end 100a of the stent 100. In an exemplary embodiment, the primary row of cells “X” includes a plurality of cells placed adjacent to each other (for example, “A, AM, B, BM, C & CM” depicted in FIG. 2b). Each cell includes four struts arranged so as to form a diamond. Two of the four struts are referred to as upper struts 102a while the remaining two of the four struts are referred to as lower struts 102b. The dimensions of the struts of a cell may differ from the dimensions of the struts of adjacent cells. Similarly, the area covered by each cell may differ from the area covered by the adjacent cell.
[40] In an example embodiment, the dimensions of various struts of the cells of primary row are as follows:
Primary row (“X”) Upper strut (102a) length Lower strut length (102b) Length of the cell Width of the cell
“A” 1.2mm to 2.4mm, more preferably 1.6mm to 2.0mm 0.5mm to 1.3mm, more preferably from 0.8mm to 1.0mm 2.2mm to 3.0mm, more preferably 2.5mm to 2.7mm 1.5mm to 2.4mm, more preferably 1.8mm to 2.1mm
“B” 1.0mm to 1.6mm, more preferably 1.2mm to 1.4mm 0.5mm to 1.2mm, more preferably 0.7mm to 1.0mm 1.6mm to 2.4mm, more preferably 1.9mm to 2.1mm 1.5mm to 2.4mm, more preferably 1.8mm to 2.1mm
“BM” Same as cell “B” Same as cell “B” Same as cell “B” Same as cell “B”
“C” 1.9mm to 2.5mm, more preferably 2.1mm to 2.3mm 0.5mm to 1.2mm, more preferably 0.7mm to 1.0mm 1.0mm to 6.0mm, more preferably 2.5mm to 4.5mm 1.5mm to 2.4mm, more preferably 1.8mm to 2.1mm
“CM” Same as “C” Same as “C” Same as “C” Same as “C”

[41] Some of the cells of primary row “X” may include one or more extensions 102c disposed at the joint of two upper struts 102a. The length of the said extension 102c is in a range of 0.2mm to 01mm, more preferably 0.4mm to 0.8mm. The extension 102c may include a coiled marker (explained in detail below).
[42] The cell structure of the cell “BM” may contain same dimensions as that of the “B” cell, and like the cell “AM”, the cell “BM” also includes extensions 102c. The extensions 102c of cell “BM” may also include coiled markers 106. The length of the said extension 102c may be in range of 0.2mm to 1.0mm, more preferably 0.4mm to 0.8mm.
[43] The cell “CM” may include same dimensions as that of the “C” cell, except the extensions 102c.The length of the said extension 102c may be in range of 0.2mm to 1.0mm, more preferably 0.4mm to 0.8mm.
[44] As shown in FIG. 2b, the struts of the stent 100 include a curved profile. For example, the radius of the curve of the primary row of cells “X” may be in a range of 0.10mm to 0.14mm, more preferably 0.11mm to 0.13mm (i.e. peak of the joint of two upper struts 102a). The primary row of cells “X” in combination with the links 104 includes a radius at an upper side (marked as “U”) which lies in a range of 0.12mm to 0.30mm, more preferably 0.17mm to 0.24mm. Similarly, a radius at a lower side (marked as “D”) may lie in a range of 0.23mm to 0.27mm radius, more preferably 0.24mm to 0.26mm radius. Owing to the curved edges, in crimped condition, the struts 102 easily rest in the lumen of the introducer sheath 403 and there is no overlapping between the links 104 and the struts with each other. Further, the curved edges provide flexible delivery at the time of deployment of the stent 100. Also, the curved edges allow the stent 100 to be crimped tightly within the delivery device 400 and help to deliver the stent 100 with a lower profile catheter.
[45] The secondary row “Y” includes diamond shaped cells having first and second struts 102a, 102b as shown in FIG. 2c. The first strut 102a of cells of the secondary row “Y” includes a length in a range of 0.8mm to 1.7mm, more preferably 1.1mm to 1.4mm. The second strut202b of the secondary row “Y” includes a length in a range of 0.5mm to 1.2mm, more preferably 0.7mm to 1.0mm. The total length of the cell of the secondary row may be in a range of 1.5mm to 2.2mm, more preferably 1.7mm to 2.0mm. The total width of the cell of the secondary row may be in a range of 1.6mm to 2.3mm, more preferably 1.8mm to 2.1mm. The first strut and second struts 102a, 102b of the secondary row cell “Y” are joined with the curved link 104 with similar radius at both the ends. The curved radius of the link 104 may be in range of 0.25mm to 0.29mm, more preferably 0.26mm to 0.28mm.
[46] The tertiary row of cells “Z” also includes diamond shaped cells having first and second struts 102a, 102b as shown in FIG. 2d. The first strut 102a of tertiary row of cells “Z” with the length in range of 0.5mm to 1.2mm, more preferably 0.7mm to 1.0mm. The second strutts202b of tertiary row of cells “Z” with the length in range of 0.8mm to 1.7mm, more preferably 1.1mm to 1.4mm. The total length of the tertiary row of cells “Z” in range of 1.5mm to 2.1mm, more preferably 1.7mm to 1.9mm. The total width tertiary row of cells “Z” is in range of 1.6mm to 2.3mm, more preferably 1.8mm to 2.1mm. The first struts102a and second struts102b of the tertiary row of cells “Z” are joined with curved link 104 with different radius at both ends. The primary row of cells “Z” in combination with the links 104 includes a radius at an upper side (marked as “U”) which lies in a range of 0.23mm to 0.27mm, more preferably 0.24mm to 0.26mm. Similarly, a radius at a lower side (marked as “D”) may lie in a range of 0.08mm to 0.12mm radius, more preferably 0.09mm to 0.11mm radius.
[47] The width and thickness of the struts in the primary row of cells “X”, the secondary row of cells “Y” and the tertiary row of cells “Z” may be same or different. The width of the struts in the primary row of cells “X”, the secondary row of cells “Y” and the tertiary row of cells “Z” may range from preferably 0.01mm to 0.20mm, more preferably it ranges from 0.05mm to 0.15mm and the thickness of the struts in the primary row of cells “X”, the secondary row of cells “Y” and the tertiary row of cells “Z” may range from preferably 0.01mm to 0.30mm, more preferably ranges from 0.05mm to 0.20mm.
[48] Further, as illustrated in FIG. 3, the stent 100 includes coiled markers 106 wrapped around one or more extensions 102c present at the distal end 100b and proximal end 100a of stent 100.The said coiled markers 106 may be made of radiopaque material. The radiopaque material may include without limitation platinum-iridium, platinum-tungsten, platinum, gold, silver, etc. In an embodiment, the coiled markers 106 are made up of platinum-tungsten material. The diameter of these coiled markers 106 ranges preferably between 0.01mm to 1.0mm, more preferably between 0.1mm to 0.8mm and the length of these coiled markers 106 ranges preferably between 0.1mm to 1.0mm, more preferably between 0.05mm to 0.95mm.
[49] The said coiled markers 106 may be wound over or attached with the help of one or more adhesives including cyanocrylates, urethane acrylate, epoxy etc. Additionally, the said coiled markers 106 may be attached by laser welding, spot welding, etc. The said coiled markers 106 may help to locate the stent 100 in fluoroscopy and/or prevent risk of damage to a vessel wall. The placement of the coiled markers 106 on the extensions provides an ease in the deployment of the stent 100 at the treatment site.
[50] Even though the present invention describes the above structure of the stent 100 as a preferred embodiment, the stent 100 may include other structures as well. For example, the stent 100 as shown in FIG. 3a includes a caged structure. Likewise, the stent 100 of FIG. 3b includes a self-expandable braided structure. The braided configuration of the stent 100 helps to provide a compact profile to the braided stent 100 for efficient deployment through the microcatheter at the implantation site. Further, the braided stent 100 has greater fatigue life, provides excellent mechanical and structural features like high tensile strength, elasticity, flexibility, softness, and abrasion resistance.
[51] In an exemplary embodiment of the present invention, the stent 100 may be coated with one or more anti-thrombogenic or anti-inflammatory agents which include without limitation phosphorylcholine, hyaluronic acid, heparin, bivalirudin, polyurethane, hirudin, plasminogen, activating factors such as streptokinase and urokinase, etc. The coating of the said agents may be performed by various methods known in the art for example, spray coating, dipping technique etc. Such a coating enhances healing of blood vessel thereby allowing vessel reconstruction and further prevents blood vessel occlusion at the implantation site.
[52] The above disclosed stent 100 is deployed at the implantation site using a delivery device 400 as depicted in FIG.4. As provided above, the delivery device 400 of the stent 100 includes a delivery wire 401, an introducer sheath 403, a coiled tip 405, distal and proximal markers 405a and 405b and a re-sheathing unit 407.
[53] The delivery wire 401 may be made from a conventional medical grade material as known to a person skilled in the art. For example, the delivery wire 401 of the present disclosure is made up of one or more materials not limited to nitinol, platinum-tungsten, stainless-steel, etc. In an embodiment, the material of the delivery wire 401 is stainless steel.
[54] Further, as depicted in FIG. 4, the said delivery wire 401 has two ends, a proximal end 401a and a distal end 401b. In an embodiment, the distal end 401b of the said delivery wire 401 is narrower as compared to the proximal end 401a of the delivery wire 401.
[55] The diameter of the proximal end 401a may range from 0.40mm to 0.50mm more preferably 0.42mm to 0.48mm. The diameter of the distal end 401b may range from 0.04mm to 0.12mm, more preferably from 0.06mm to 0.10mm. In an exemplary embodiment, the diameters of the proximal end 401a and the distal end 401b are 0.40mm and 0.09mm respectively. The length of the narrowed (tapered) region is 500mm to 700mm, more preferably up to 550mm to 650mm while the total length of the delivery wire 401is in the range of 1800mm to 2000mm, more preferably 1850 to 1950 mm of length.
[56] Additionally, the said delivery wire 401 may be coated with a polymeric coating. The said coating renders smooth movement and easy trackability as well as pushability thus ensuring low coefficients of friction during deployment. The polymeric material used for the coating may include teflon, PFA (perfluoroalkoxy alkane), PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene) etc. In an embodiment of the present disclosure the polymeric coating is PTFE (polytetrafluoroethylene). In an embodiment, the distal end 401b of the delivery wire 401 which includes the stent 100 is non-coated thereby allowing easy deployment procedure and effective attachment of markers.
[57] Further, the distal end 401b of the delivery wire 201 includes a coiled tip 405. The said coiled tip 405 is made of one or more radiopaque material including platinum-tungsten, platinum-iridium, stainless steel, titanium, stainless steel, nitinol etc. In a preferred embodiment, the coiled tip 405 is made of platinum-tungsten. The outer diameter of the coiled tip 405 is 0.30mm to 0.40mm, more preferably 0.34mm to 0.38mm. The length of the coiled tip 405 may range from 10mm to 20mm. The coiled tip 405 may include a bent configuration. Such a configuration helps in preventing the vessel wall from rupturing by the tip of the delivery wire 401 during the deployment of the stent 100 in the tortuous vasculature.
[58] The proximal and distal ends 401a, 401b of the delivery wire 401 includes one or more radiopaque markers. The radiopaque markers made up of gold, silver, platinum, etc., or alloys of metals such as platinum-tungsten, platinum-iridium, etc. In the preferred embodiment, the markers are made of platinum-iridium material. The iridium material in combination with platinum material provides strength to the markers and also aids in radiopacity of marker under fluoroscopic examination. The radiopaque markers placed at the proximal end 401a of the delivery wire 401 may be in the form of hollow conical members.
[59] The length of the radiopaque marker at the distal end 401b is 1.0mm to 5mm, more preferably in between 2.0mm to 2.5mm. The radiopaque marker placed over the distal end 401b includes a length in range of 1.0mm to 5mm, more preferably in between 2.0mm to 2.5mm. The marker placed over the distal end 401b includes an outer diameter of 0.50mm to 0.60mm, more preferably in between 0.54mm to 0.58mm and a tapered diameter of 0.35mm to 0.40mm.The inner diameter may range from 0.18mm to 0.23mm. The diameter & length of the stent 100 may affect the position of the marker at the distal end 401b. The change in position of the marker at the distal end 401b largely affects its internal diameter because of the tapered delivery configuration of the delivery wire 201 which leads to change in the inner diameter of the one or more markers from 0.18mm to 0.23mm.
[60] The marker placed over the proximal end 401a includes an outer diameter of 0.40mm to 0.50mm, more preferably in between 0.45mm to 0.50mm. The inner diameter of the said marker may range between 0.05mm to 0.15mm, more preferably in between 0.08mm to 0.12mm. The marker placed over the proximal end 401a includes a length of 0.5mm to 2.0mm; more preferably, 0.8mm to 1.5mm.
[61] The delivery wire 401 further includes a re-sheathing unit 407 which is placed over the proximal marker allowing stent 100 re-sheathing after partial deployment. The re-sheathing unit 407 of the present invention may include a coil, silicone tube, PEBAX tube or any of the soft polymer tube etc.
[62] In an embodiment, the re-sheathing unit 407 is a coil made of nitinol or platinum-tungsten. The length of the re-sheathing unit 407 may range preferably from 0.5mm to 5.0mm, more preferably from 1mm to 4mm. The said re-sheathing of the stent 100 is performed by an effective gripping of stent 100 over the re-sheathing unit 407.
[63] In the present embodiment, to deploy the stent 100 at the implantation site, the delivery device 400 is compatible with any of the commercially available microcatheter having 2.4Fr to 2.7Fr profile and length of 100cm to 150cm.
[64] Further, the delivery device 400 is enclosed in an introducer sheath 403. The introducer sheath 403 can be made up of one or more materials including PTFE, polyimide, PEBAX, nylon, FEP, silicone etc. In an embodiment, the introducer sheath 403 of the present invention is made from a combination of PTFE-Nylon mixture.
[65] The introducer sheath 403 may include one or more layers. In an exemplary embodiment of the present invention, the introducer sheath 403 may be a dual layered transparent polymeric tube. The outer and inner layers of the introducer sheath 403 are formed of nylon and PTFE respectively. In the present embodiment, the lumen diameter (i.e. inner diameter) of the introducer sheath 403 may be in a range of 0.40mm to 1.00mm, more preferably in the range of 0.60mm to 0.80mm. Further, the thickness of the wall of the introducer sheath 403 is 0.05mm to 0.25mm, more preferably the thickness may be in the range of 0.10mm to 0.20mm. Further, length of the introducer sheath 403 is 500mm to 1000mm and more preferably from 600mm to 800mm. The diameter and length of the said introducer sheath 403 is so defined that the stent 100 and the tapered portion of the delivery device 400 enter into proximal end 100a of a standard 0.022”- 0.027” (2.4-2.7 F) microcatheter during deployment of the stent 100 without any structural deformation. The outer diameter of the introducer sheath 403 is lesser than the inner diameter of microcatheter for ease in access through the microcatheter during deployment of the stent 100.
[66] The stent 100 is deployed using the above disclosed components of the delivery device 400. Prior to deployment, the stent 100 is enclosed in the introducer sheath 403. The catheter of the delivery device 400 is pulled proximally, due to which the distal flared portion of the stent 100 protrudes outwards. In case, during the deployment procedure, the stent 100 is required to be realigned, the stent 100 can be re-sheathed by pushing the microcatheter. Subsequently, post re-alignment of the stent 100 at the required zone, the stent 100 may be deployed again.
[67] As provided above, the above disclosed stent 100 may be utilized for treating intracranial plaques as shown in FIG. 4a and aneurysm as shown in FIG. 4b. As shown in FIG. 4a, the stent 100 is in contact with the affected blood vessel. Owing to the self-expanding property and the radial force of the stent 100, the damaged blood vessel is pushed outwards as shown in FIG 4a.
[68] For treating aneurysms as shown in FIG. 4b, the stent 100 blocks the coil used to treat aneurysm. The stent 100 first covers the aneurysm present in the vessel of the human body. A microcatheter is then inserted into the vessel and is passed over a cell of the stent 100 and then into the aneurysm so that the embolic coils may be delivered through the microcatheter.
EXAMPLES
Example 1 (prior art)
[69] A stent having an open-cell design and zig-zag shaped geometry was implanted to treat intracranial aneurysms as depicted in FIG.5a. The stent included struts and links having curved edges. The width of the struts in the present example is about 0.1mm. Additionally, the curved edges forms peaks respectively known as first and second peaks. The radius of the first peak is about 0.14mm and the radius of the second peak is about 0.05mm. The length of each peak is about 1.3mm. Likewise, sharp “S” shaped links also possesses two curved shaped portions i.e. first curve and second curve. The length of the “S” shaped link is about 1.0mm and radius of about 0.2mm. Further, the radial force exerted by the stent is about 146gf.
[70] The stent did not provide any provision for re-sheathing of the stent. Further, as depicted in FIG. 5b, the peaks of the stent tend to extend outwards thereby increasing the chances of penetration of aneurysm.
Example 2 (present invention)
[71] In the present example, a stent having a closed-cell design was implanted to treat intracranial aneurysms as depicted in FIGs. 6a and 6b. The closed-cells of the stent were divided into three rows of cells i.e. primary, secondary and tertiary row of cells. Additionally, pluralities of straight links or connectors are present in the stent. The stent includes two ends i.e. a proximal end and distal end. The primary, secondary and tertiary rows of cells have pre-defined dimensions with varying lengths and diameters. Each cell of the primary row of cells includes first and second struts. The radius of the respective first and second struts is about 0.22mm and about 0.25mm.
[72] The secondary row of cells includes diamond shaped cells. The said diamond shaped cells are joined via curved links with a similar radius of about 0.27mm at both ends.
[73] The tertiary row of cells also includes diamond shaped cells; however the curved links includes links with different radius at both the ends i.e. 0.25mm at the first portion and 0.10mm at the second portion.
[74] The advantage of providing curved edges includes effective placement of the stent in the tortuous intracranial vessels thereby preventing kinking of the stent. Moreover, the primary row of cells at the proximal and distal ends of the stent provides an added advantage during the deployment of the stent at the treatment site.
[75] Additionally, the stent was constructed in a way such that the stent can be re-sheathed even after 60%-70% of deployment. The presence of the coiled markers on the primary row of cells provides enhanced trackability and the stent configuration may give maximum compressive force of 1.61N and radial force of 766gf without any structural deformation of the stent i.e. stent fracture and/ or kinking.
[76] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used.