Claims:1. An implant (100) comprising:
a proximal end (100a);
a distal end (100b),
a first frame (10a) having a first proximal end (10a1) and a first distal end (10a2), the first distal end (10a2) being aligned to the distal end (100b), the first frame (10a) having a coupling mechanism on at least one of the first proximal end (10a) or the first distal end (10a2); and
a second frame (10b) having a second proximal end (10b1), and a second distal end (10b2), the second proximal end (10b1) being aligned to the proximal end (100a), the second frame (10b) being coupled to the first frame (10a) via the coupling mechanism provided on the first proximal end (10a) or the first distal end (10a2);
wherein the first frame (10a) includes a plurality of rows of closed cells (CC);
wherein the second frame (10b) includes a plurality of rows of closed cells (CC) as well as open cells (OC).
2. The implant (100) as claimed in claim 1 wherein at least one of the proximal end (100a) and the distal end (100b) is flared.
3. The implant (100) as claimed in claim 1 wherein the first frame (10a) is made of nitinol.
4. The implant (100) as claimed in claim 1 wherein the first frame (10a) includes a braided configuration.
5. The implant (100) as claimed in claim 4 wherein the first frame (10a) has a braid angle of 100° to 400°.
6. The implant (100) as claimed in claim 4 wherein the braiding configuration comprises one by one braiding configuration.
7. The implant (100) as claimed in claim 1 wherein the first frame (10a) includes a closed cell structure.
8. The implant (100) as claimed in claim 1 wherein the coupling mechanism includes a plurality of updown loops (10a3).
9. The implant (100) as claimed in claim 1 wherein the second frame (10b) is made of nitinol shape memory alloy.
10. The implant (100) as claimed in claim 1 wherein the second frame (10b) is a laser cut frame.
11. The implant (100) as claimed in claim 1 wherein the closed cells (CC) and open cells (OC) of the second frame (10b) are coupled to each other with the help of a plurality of links ‘L’.
12. The implant (100) as claimed in claim 1 wherein the second frame 10b is covered with a polymeric covering.
13. The implant (100) as claimed in claim 12 wherein the polymeric covering of the second frame (10b) comprises one or more degradable or non-degradable polymers including PTFE (polytetrafluoroethylene), ePTFE (expanded polytetrafluoroethylene), silicone, (fluorinated ethylene propylene)FEP, PLLA (polylactic acid), PLGA (poly(lactic-co-glycolic acid), PCL (polycaprolactone) or combinations thereof. , Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

TITLE OF THE INVENTION:
TRANSJUGULAR INTRAHEPATIC PORTOSYSTEMIC SHUNT IMPLANT

APPLICANTS:
Meril Life Sciences Pvt Ltd., an Indian company, of the address Survey No. 135/139 Bilakhia House, Muktanand Marg, Chala, Vapi- 396191, Gujarat

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

FIELD OF INVENTION
[001] The present invention relates to a medical implant, more specifically, a transjugular intrahepatic portosystemic shunt implant.
BACKGROUND
[002] The liver serves many functions within the body from making carbohydrates, proteins and fats to synthesizing bile for digestion of food. In order to perform the said functions, the liver requires a significant blood supply and around 75% of this blood supply comes from the portal venous system.
[003] Portal hypertension is an increase in the blood pressure within the portal venous system. Veins coming from the stomach, intestine, spleen, and pancreas merge into the portal vein, which then branches into smaller vessels and travels through the liver. In cases where the vessels in the liver are blocked due to liver damage, blood is not able to flow properly through the liver and hence, high pressure in the portal system is developed. This increased pressure in the portal vein may in turn cause development of large, swollen veins within the esophagus, stomach, rectum, or umbilical area (belly button), thereby leading to life-threatening complications.
[004] In order to treat portal hypertension, transjugular intrahepatic portosystemic shunt (TIPS or TIPSS) was introduced in the year 1969. TIPS is an artificial channel which is provided within the liver to establish a communication between the portal vein and the hepatic vein. TIPS have proven to be a promising procedure for safe decompression of the portal system and effective control of blood pressure flow.
[005] Ever since the advent of this procedure, various systems have been proposed. In recent practice, varied stent platforms have been used as artificial channels. However, the conventional stents pose various challenges. For example, the said stents mostly require a pull wire or a thread for their deployment. Such deployment mechanisms may cause improper deployment of the stent as the pull wire or the thread is susceptible to breakage/damage due to unstable forces.
[006] Further, most of the conventional designs are either laser cut or knitted/braided. The laser cut stents are prone to kinking at puncture site because of their placement at bending segments of the liver anatomy. Likewise, fully knitted/braided stents also have low efficiency due to high flexibility, low radial properties and large pore size of such stents.
[007] Therefore, an improved system for TIPS which overcomes the disadvantages of the conventional systems is required to be devised.
SUMMARY
[008] The present invention relates to a transjugular intrahepatic portosystemic shunt implant. The implant includes a proximal end and a distal end, a first frame having a first proximal end and a first distal end and a second frame having a second proximal end, and a second distal end. The first distal end is aligned to the distal end. The first frame further includes a coupling mechanism on at least one of the first proximal end or the first distal end. The second proximal end is aligned to the proximal end. The second frame is coupled to the first frame via the coupling mechanism provided on the first proximal end or the first distal end. The first frame includes a plurality of rows of closed cells. The second frame includes a plurality of rows of closed cells as well as open cells. The second frame includes a polymeric covering.
BRIEF DESCRIPTION OF DRAWINGS
[009] 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.
[0010] FIG. 1 depicts an implant 100 being deployed at an implantation site in accordance with an embodiment of the present invention.
[0011] FIG. 2 depicts the exploded view of the implant 100 in accordance with an embodiment of the present invention.
[0012] FIGs. 3a-3b represents a first frame 10a in accordance with an embodiment of the present invention.
[0013] FIGs. 3c-3e represents a second frame 10b in accordance with an embodiment of the present invention.
[0014] FIG. 4 a mandrel 20 in accordance with an embodiment of the present invention.
[0015] FIGs. 5-5b depicts the attachment between the first frame 10a and the second frame 10b in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] In accordance with the present disclosure, a medical implant to be employed as a transjugular intrahepatic portosystemic shunt is disclosed. The implant is useful for treatment of liver diseases such as portal hypertension, gastrointestinal bleeding, hepatic encephalopathy (HE), refractory ascites, etc. The implant of the present invention helps to establish a shunt through a portal vein and a hepatic vein for diverting the blood flow at an implantation site. The implantation site in the present invention corresponds to the intrahepatic tract of the liver. The implant helps to divert and increase the blood flow from the liver thereby reducing blood pressure in the portal vein as well as reducing any associated risk of bleeding of the dilated veins.
[0021] The implant of the present invention is a self-expanding implant. The implant includes two frames i.e. a first frame and a second frame. The first frame is designed to reside in the portal vein. The first frame includes less metal ratio which in turn helps to render high flexibility to the first frame in order to maintain blood flow.
[0022] The second frame is positioned in the hepatic vein of the intrahepatic tract. The second frame includes a covering on its outer surface. The covering corresponds to a polymer covering having self-reinforcing properties, high radial resistance and resistance to damage caused by bile and other fluids is provided over the second frame. The polymeric covering further allows passage of the blood through the portal vein to the hepatic vein without any leakage through the implant surface. The second frame allows easy implantation of the implant and helps the implant to navigate easily through the curved anatomy of the implantation site without any damage to the vessels or the implant itself.
[0023] The first frame and the second frame are assembled together to constitute the hybrid structure of the implant. Such a hybrid structure of present invention helps to maintain proper grip at the portal vein to avoid any migration problems and also helps to avoid leakage after implantation.
[0024] The implant may be flared at both its ends for maintaining proper grip and hold at the implantation site while diverting blood flow. The implant includes three markers disposed at different locations for ensuring accurate placement of the implant between the portal vein and the hepatic vein.
[0025] The implant of the present invention is deployed via a 7Fr to 10Fr compatible delivery system. The delivery system operates via a push-pull mechanism. The said delivery system allows easy and accurate placement of the implant in the intrahepatic tract.
[0026] Now referring to figures, FIG.1 depicts the implant 100 being disposed at the implantation site i.e. intrahepatic tract 1a of the liver 1. The placement of the implant 100 is carried out via an endoluminal pathway through a jugular vein (not shown) which links a portal vein 1b disposed towards an inferior vena cava 1c to a hepatic vein 1d. As depicted in FIG. 1, the implant 100 is placed between the hepatic vein 1d and the portal vein 1b. The structure of the implant 100 is more clearly depicted in FIG. 2.
[0027] In accordance with FIG. 2 of the present invention, the implant 100 may include a body defined between a proximal end 100a and a distal end 100b. The proximal and distal ends 100a, 100b may be flared. The flared proximal and distal ends 100a, 100b prevent migration of the implant 100 thereby allowing the implant 100 to be held firmly at the implantation site. In the present invention, the difference between the diameter of the proximal and distal ends and the diameter of the rest of the body of the implant 100 may range from 0.1mm to 3.0mm, more preferably from 0.5mm to 1.5mm.
[0028] Further, the implant 100 includes a plurality of sections which are linked together to form the implant 100. Such sections may include distinct properties such as, without limitation, flexibility, softness and radial strength. In an embodiment of the present invention as depicted in FIG. 2, the implant 100 includes a first frame 10a and a second frame 10b. In an embodiment, the first frame 10a is highly flexible. Such flexibility of the first frame 10a helps the implant 100 to be held firmly inside the vein and further assists in forming a grip for the transfer of blood. The second frame 10b may be less flexible and may include a higher radial strength and kink resistive properties. Such properties help the implant 100 to be deployed at implantation sites having high bending curves (as per a patient’s anatomy).
[0029] The first frame 10a is placed towards the proximal end 100a or the distal end 100b of the implant 100. In an embodiment as depicted in FIG. 2, the first frame 10a is disposed at the distal end 100b. The first frame 10a may include a first proximal end 10a1 and a first distal end 10a2. The first proximal end 10a1 may be attached to the second frame 10b while the first distal end 10a2 may correspond to the distal end 100b of the implant 100.
[0030] The total length of the first frame 10a may be in a range 10mm to 40mm; more preferably 15mm to 35mm. The diameter of the first frame 10a may be in a range of 4mm to 14mm, more preferably 8mm to 12mm.
[0031] The first frame 10a may be made up of conventionally known metals such as, without limitation, cobalt chromium, stainless steel, nitinol, nitinol platinum core wire, platinum or platinum tungsten material, etc. In an embodiment of the present invention, the first frame 10a is made of nitinol. Nitinol is used for preparation of the first frame 10a because of its pronounced self-expanding properties as compared to other materials.
[0032] As a preferred embodiment, the first frame 10a is made via braiding of nitinol wires. However, as per the teachings of the said invention, the first frame 10a may be manufactured by other techniques such as laser cutting, knitting or braiding, etc. The first frame 10a includes a plurality of closed cells. The size of the said closed cells may be increased for a given diameter of the first frame 10a to obtain a first frame having a less metal ratio and high flexibility. The increase in the size of the closed cells in turn reduction in the number of wires to be used for braiding. In an embodiment, around 8 to 32 wires, preferably, 12 to 24 wires are braided together to create the first frame 10a.
[0033] In an embodiment, the wires used for preparing the first frame 10a may be monofilament or multifilament. The wire diameter may be in a range of 50micron to 300micron, more preferably 100micron to 200micron.
[0034] The braiding configuration adopted for preparation of the first frame 10a may be one of, one by one, one by two, two by two, etc. In an embodiment, one by one braiding configuration is adopted for manufacturing the first frame 10a. The braid angle may be in a range of 30° to 500°; more preferably 100° to 400°.
[0035] As represented in FIGs. 2 and 3a, the first frame 10a is braided in such a way that at least one of the first proximal end 10a1 and/or the first distal end 10a2 of the first frame 10a includes long updown loops 10a3. Such a structure may be formed using a mandrel 20 (as shown in FIG. 4).
[0036] In an embodiment, the length of the updown loops 10a3 range from 2mm to 6mm, more preferably 3mm to 4mm. The number of updown loops 10a3 may vary between 1 to 4 loops. The updown loops 10a3 help to maintain the flexibility of the implant 100 at a point where the first proximal end 10a1 is coupled to the second frame 10b.
[0037] Alternately, as represented in FIG. 3b, the first frame 10a includes a closed loop structure at both its sides without any updown loops 10a3.
[0038] Further, the first frame 10a may further include a plurality of markers. The markers may be placed at the first proximal end 10a1 and the first distal end 10a2. In an embodiment, 2 to 10 markers are placed for radiopacity, more preferably 4 to 8 markers are used. The radiopaque markers may be designed in the form of a tube, coil, sheet or any other design. In an embodiment, the first frame 10a includes tube shaped markers which help to maintain flexibility and profile of the implant 100.
[0039] The radiopaque markers are made from a biocompatible material such as platinum, iridium, platinum tungsten, tantalum, gold or their combination. In an embodiment, markers made from platinum tungsten material are used in the present invention. The markers may include an internal diameter of 50-300 micron and a wall thickness of 2-5 micron.
[0040] The second frame 10b may include a second proximal end 10b1, a second distal end 10b2 and an intermediate portion 10b3. The second proximal end 10b1 is disposed towards the proximal end 100a of the implant 100 as depicted in FIG. 2. The second distal end 10b2 may be coupled to the first proximal end 10a1 of the first frame 10a.
[0041] The second frame 10b may be made from conventionally known material such as
nitinol, platinum-iridium alloys, stainless steel, cobalt chromium alloys including elgiloy. In an embodiment, the second frame 10b is made of nitinol shape memory alloy.
In an embodiment, the second frame 10b is formed via laser cutting. However, as per the teachings of the present invention, the second frame 10b may be fabricated using conventional techniques such as laser-cutting, braiding/knitting, etc.
[0042] As represented in FIG. 3c, the second frame 10b may include a plurality of rows of closed cells (CC) as well as open cells (OC). In an embodiment, the second proximal end 10b1 and the second distal end 10b2 include closed cells (CC) while the intermediate portion 10b3 includes open cells (OC) to improve the flexibility of the second frame 10b. Further, such a design also promotes easy loading of the implant 100.
[0043] The total number of cells may range from 8-16 radially, more preferably 10-14. However, it should be noted that the number of cells may also increase with increase in the diameter of the second frame 10b. The diameter of the second frame 10b may range from 4mm to 14mm, more preferably 8mm to 12mm. The second frame 10b may include a total length in a range of 20mm to 200mm, more preferably 60mm to 120mm.
[0044] The closed cells ‘CC’ of the second frame 10b may be attached with the open cells ‘OC’ with the help of plurality of links ‘L’ as shown in FIG. 3c. Further, as represented in FIG. 3c, in closed cells ‘CC’, a pair of zig-zag struts is connected together via the link ‘L’ to form a hexagonal shaped crown. The zig-zag shaped struts may correspond to peaks of the closed cell ‘CC’. The links of the closed cell may be designed as a straight structure or a curve. In a preferred embodiment, the links are straight in configuration.
[0045] The width of the link ‘L’ of the closed cells ‘CC’ may be same as the width of the struts. In an embodiment, the width of the link is range from 0.08mm to 0.18mm, more preferably 0.10 mm to 0.14mm. The length of a strut in the closed cell ‘CC’ may range from 2.0mm to 3.0mm, more preferably 2.2mm to 2.6mm. The strut thickness may range from 0.10mm to 0.20mm, more preferably 0.12 mm to 0.18mm.
[0046] The length cell offset (CO) as shown in the FIG. 3d for a closed cell may be in a range of 3.0mm to 6.0mm, more preferably 3.5mm to 5.0mm. The mean cell spacing (MCS) of the closed cells ‘CC’ may be less as compared to the MCS of the open cell. In an embodiment, the MCS of the closed cells ‘CC’ ranges from 2.0mm to 3.0mm, more preferably 2.2mm to 2.6mm. The length of the peak ‘P’ as shown in FIG. 3d may range from 0.2mm to 0.3mm; more preferably 0.22mm to 0.26mm. The strut angle ‘a’ i.e. the angle formed after the expansion of the implant 100, may range from 90° to 130°; more preferably 100° to 120°.
[0047] The open cell structure ‘OC’ may include 04 to 30 peaks, more preferably 06 to 20 peaks that are circumferentially disposed. The struts in the open cells ‘OC’ are also interconnected via links ‘L’. However, the link ‘L’ in the open cells are less than the number of links ‘L’ in the closed cells ‘CC’. The links ‘L’ is arranged in such a manner that the strength of the second frame 10b is maintained as well as the flexibility and bending property of the second frame 10b is enhanced.
[0048] The width of the links may be same as the strut width of the cells. The width of the links may be in a range from 0.08mm to 0.18mm, more preferably 0.10mm to 0.14mm.
[0049] The length of the struts in the open cells ‘OC’ may be in a range of 1mm to 3mm; more preferably 2.2mm to 2.6mm. The strut thickness of the open cells ‘OC’ may be in a range of 0.10mm to 0.20mm; more preferably 0.12 mm to 0.18mm. The length of the peak ‘P’ as shown in FIG. 3e may be in a range of 0.2mm to 0.3mm; more preferably 0.22mm to 0.26mm. The length of the open cell ring cell offset ‘CO’ may be in a range of 3.0mm to 6.0mm; more preferably 3.5mm to 5.0mm. The mean cell spacing ‘MCS’ of the open ring cell may be in a range of 2.0mm to 3.0mm; more preferably 2.2mm to 2.6mm. The strut angle ‘a’ (angled formed after the expansion of the implant 100) of the open cell ring may be in a range of 90° to 130°; more preferably 100° to 120°.
[0050] In an embodiment, the first frame 10a and the second frame 10b may be secured with each other as shown in FIG. 5. The first frame 10a and the second frame 10b may be joined by way of interweaving. Each braided thread of the first frame 10a may be interwoven with the close cells ‘CC’ of the second frame 10b at the second distal end 10b2. As represented in FIG. 5b, in case of updown loops 10a3, the loops having longer length are attached at the second distal end 10b2 of the second frame 10b. Such a combination helps to maintain the placement of the first frame 10a to hold the portal vein 1b and the second frame 10b to act as a bridge between the portal vein 1b and hepatic vein 1d. In an embodiment, the first frame 10a covers around 10% to 30% of the length of the total implant 100.
[0051] In another embodiment as depicted in FIG. 5a, the updown loop 10a3 of the first frame 10a overlap with the closed cells ‘CC’ of the second frame 10b at specific points which are at least distance from the second distal end 10b2. Such a combination allows easy bending of the implant 100 due to high flexibility. Also, better fixation and reduced chance of leakage are achieved.
[0052] In an embodiment of the present invention, one or more markers are attached at one of the second proximal end/the second distal end 10b1, 10b2 of the second frame 10b for better visibility of the implant 100. In present embodiment, 02 to 06 markers are attached on the one side for the visibility of the second frame 10b under fluoroscopy; more preferably 03 to 04 markers are attached on the one side of the second frame 10b. These markers are may be round or tube shaped which are press fit or laser welded.
[0053] Further, a covering is provided over the second frame 10b. The said covering may be provided by many ways like adhesion, spray coating, electrospining, etc. Such covering includes self-reinforcing properties, high radial resistance and resistance to damage caused by bile and other fluids. The covering further allows passage of the blood through the portal vein to the hepatic vein without any leakage through the implant surface.
[0054] In an embodiment, the covering is a polymeric covering being composed of one or more degradable or non-degradable polymers. The non-degradable polymers may include, without limitation, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), silicone, fluorinated ethylene propylene (FEP), etc. The degradable polymers may be selected from say, polylactic acid (PLLA), poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), etc. In an embodiment, expanded polytetrafluoroethylene (ePTFE) is used. This ePTFE may include an unsintered membrane with a preferred thickness ranging from 0.003 mm to 0.10 mm, more preferably thickness ranges from 0.005 mm to 0.09 mm. Such low thickness of ePTFE helps to maintain the low profile of the implant 100. The dimensions and the number of ePTFE films required to cover the second frame 10b is dependent upon the inner or outer diameter of frame and the thickness of the film along with the number of wraps required.
[0055] Thus, depending on the thickness of the film and inner and outer diameters of the second frame 10b, the numbers of wraps or films are calculated. In an embodiment, two films were minimally required to provide an appropriately thick ePTFE covering/film with a 0.5mm thick film placed over the entire length of the second frame 10b.
[0056] The ePTFE layer may be covered on the implant surface via for example, heating, coating, gluing etc. In preferred embodiment, an ePTFE layer is covered on an inner or an outer surface of the implant 100 by applying heat which secures the polymer onto the implant 100. The said covering may be easily expanded without reducing the flexibility of the implant 100.
[0057] In an embodiment, in order to provide the ePTFE covering over the implant 100, the mandrel 20 is used (as shown in FIG.4). The mandrel 20 provides smooth covering of ePTFE without any crack and wrinkles. The said mandrel 20 may be made from a polymeric or a metal material like teflon, HDPE, stainless steel, nitinol etc. In this present invention, the mandrel 20 is made of stainless steel material. The mandrel 20 contains one or more holes 20a to circulate air. Also, a central hole 20a1 is provided over the mandrel 20 which provides uniform heat exchange throughout the surface of the mandrel 20. The mandrel 20 also includes a slit 20b which helps to remove the covered implant 100. In an embodiment, the central hole 20a1 includes a diameter of 2.5 mm, the one or more air hole 20a include a diameter of 1.95mm and the slit 20b includes a diameter of 1mm–2mm.
[0058] For providing the covering over the second frame 10b, the mandrel 20 mounted with the implant 100 having the ePTFE layer was heated at a temperature of about 150°C to 300°C for 05min to 30 min; more preferably 180°C to 220°C for 10min to 25 min respectively. To shrink the ePTFE layer properly, a heat shrink tube was laid over the ePTFE layer for protecting the outer surface which is directly in contact to heat. The dimensions of the heat shrink tube may be more than the implant dimensions, particularly the diameter. The heat shrink tubes used in the present invention may include fluorinated ethylene propylene, PTFE, nylon, pebax etc. In an embodiment, fluorinated ethylene propylene is used. Subsequently, the mandrel 20 having the implant 100 is cooled at the normal temperate to gain the strength of graft bonding. The mandrel 20 may be cooled for say, 1 min to 15 mins; more preferably 5mins to 10 mins. Post cooling, the heat shrink tube is removed.
[0059] The first and second frames 10a, 10b as described above, may be attached together using a coupling mechanism or some pre-defined methodologies as defined below.
[0060] Examples:
[0061] Example 1(Prior art): A metallic frame made up of nitinol with both flared ends was employed to be used as a transjugular intrahepatic portosystemic shunt. The said frame included a covering of a polymeric material i.e. PTFE (polytetrafluoroethylene) over the entire frame. Further, the said stent was placed in the intrahepatic tract for the proper flow of the blood through the vessels. It was observed that the implant of Example 1 was prone to migration and dislocation from the implantation site due to improper deployment at target location and high blood pressure at portal vein.
[0062] Moreover, it was observed that the deployment of the frame at the implantation site created blood leakage due to blood vessel rupture. Further, if the frame is deployed deep inside the portal vein, the frame blocks the portal vein due to thrombosis thus, resulting in implant dysfunction.
[0063] Example 2(Present Invention): An implant having two frames i.e. a covered laser cut frame and a non-covered braided frame was implanted at the intrahepatic tract. The laser cut frame was covered with an ePTFE cover and had open and closed cell configuration. The non-covered frame included closed loop structure with up down loops. The non-covered frame was attached to the covered frame using the up down loops. The implant was delivered using a delivery system equipped with push-pull mechanism and was compatible with 7Fr and/or 10Fr compatibility.
[0064] It was observed that the combination of frames was easily deployed in the veins. Thus, providing an enhanced flexibility to the frames and compatibility with the push-pull mechanism during deployment. Moreover, the uncovered frame will not affect the flow of the blood in the portal vein which may further result in thrombosis.
[0065] 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.