Claims:WE CLAIM:
1. A placement device for an intracranial or a cerebral vessel that can be accessed in the vessel via a trans-femoral route, a trans-jugular route, a trans-venous route or a trans-radial route, the device comprising:
a. a delivery wire having a proximal end and a distal end, the delivery wire being tapered at the distal end;
b. a thickening unit coupled to the distal tapered end of the delivery wire;
c. a polymeric tube provided over the thickening unit that extends partially over the delivery wire; and
d. a hydrophilic coating provided on assembly of the delivery wire, thickening unit and the polymeric tube.
2. The placement device as claimed in claim 1 wherein the delivery wire comprises one or Nitinol or cobalt chromium.
3. The placement device as claimed in claim 1 wherein the thickening unit comprises a radiopaque coil.
4. The placement device as claimed in claim 3 wherein the radiopaque coil comprises one of platinum iridium or platinum tungsten.
5. The placement device as claimed in claim 1 wherein the polymeric tube comprises of heat shrunk PTFE material.
6. The placement device as claimed in claim 1 wherein the delivery wire is coated with a hydrophilic material.
7. The placement device as claimed in claim 1 wherein length of the delivery wire ranges from 1700mm to 2300mm.
8. The placement device as claimed in claim 1 wherein length of the thickening unit ranges from 25mm to 35mm.
9. The placement device as claimed in claim 1 wherein diameter of the thickening unit ranges from 0.025mm to 0.085mm.
10. The placement device as claimed in claim 1 wherein the proximal end is non-tapered and coated with a PTFE material.
11. The placement device as claimed in claim 1 wherein the proximal end of the delivery wire includes one or more flouro-safe markers. , 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:
THRUST WIRE FOR NEUROVASCULAR OR CEREBROVASCULAR DEVICE

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

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

FIELD OF INVENTION
[001] The present disclosure relates to a placement device for delivering a medical implant at a treatment site and the method of manufacturing thereof.
BACKGROUND
[002] Before minimal invasive surgery was developed, there were complicated invasive surgeries requiring invasions involving large cuts on skin, organs and/or other body parts.
[003] The minimal invasive surgery utilizes a placement device, generally used to transport a medical implant at a treatment site. The design of the said placement device is based on various application requirements and the treatment sites. For example, a simple stainless steel delivery wire with less flexibility can solve the purpose when the implant or the prosthesis attached to said delivery wire has to be delivered to the peripheral arteries or veins. Similarly, if the delivery wire is required to be used for cardiovascular application, a simple straight delivery wire may be used.
[004] However, if the implant has to reach a neurovascular site like ICA (Internal carotid artery) segment or MCA (Middle Cerebral Artery) region which are highly tortuous and complex regions, the wire must be highly flexible so that the implant can reach the neurovascular site easily and swiftly without causing any damage to the vessels.
[005] The delivery wires known earlier were made up of stainless steel. However, the flexibility of the stainless steel wire is less and it has high tendency to kink. Moreover, significant hindrance is caused in its positioning due to high thrust force while deploying the implant. Apart from that, stainless steel wire also leads to arterial damage, puncture or perforation to the vessel due to stiff tip at the end. Due to stiffness in stainless steel material, the rate of friction is also very high thus the wire is not versatile and has limited use.
[006] Hence, to overcome the above mentioned shortcomings, there is a need for an improved placement device.
SUMMARY
[007] The present invention discloses a placement device for an intracranial or cerebral vessel. The placement device of the present invention contains a tapered delivery wire having a proximal end and a distal end. The distal end of the delivery wire is narrower than the proximal end. Further, a thickening unit is coupled to the distal end of the delivery wire. The thickening unit of the present invention is a radiopaque coil made from platinum iridium or platinum tungsten.
[008] Additionally, a heat shrink polymeric tube is provided over the thickening unit. The said polymeric tube is present over the coil which reduces the thrust force delivered by the delivery wire. The delivery wire further contains a fluoro-safe marker which helps to efficiently locate the implant at the time of deployment and keeps a track of the movement of the delivery wire to determine whether it has crossed a carotid artery or not. This in turn helps to track the position of the implant and it is easily ascertained that the implant has reached near the intracranial region. The placement device including the thickening unit, the fluoro-safe marker and the coil is further hydrophilic coated.
[009] The foregoing features and other features as well as the advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] 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.
[0011] FIG.1 depicts the intracranial vessels treatment site where the delivery wire is used for delivering neurovascular device, in accordance with an embodiment of the present invention.
[0012] FIG.2 describes the complete assembly of the delivery thrust wire, in accordance with an embodiment of the present invention.
[0013] FIG.2A illustrates the radiopaque coil which is to be attached at distal end of the wire, in accordance with an embodiment of the present invention.
[0014] FIG.2B shows PTFE heat shrink wrap over thrust wire, in accordance with an embodiment of the present invention.
[0015] FIG.2C depicts the safety fluoro-safe marker on delivery wire, in accordance with an embodiment of the present invention.
[0016] FIG.3 shows attachment of coil onto delivery wire i.e. via laser spot welding using laser welding probe, in accordance with an embodiment of the present invention.
[0017] FIG.4 shows attachment of implant on thrust wire, in accordance with an embodiment of the present invention.
[0018] FIG.5 shows a flowchart depicting the process for manufacturing the placement device and the steps involved in its deployment, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] 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.
[0020] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings, however, it is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[0021] The present invention discloses a placement device used to deliver a medical implant (or implant) at the treatment site. The treatment site of the present disclosure may include one or more intracranial or cerebral vessels. The implants that can be delivered by the placement device of the present disclosure may be, without limitation, a clot retrieval device, an embolization coil, a flow diverter, a bifurcation aneurysm stent, a coil assisting device, etc.
[0022] The placement device of the present invention includes a delivery wire (or wire) which has a tapered configuration, i.e. a distal end of the wire is narrower compared to a proximal end of the wire. The delivery wire includes a thickening unit provided at its distal end. The placement device further includes a polymeric tube that is heat shrunk on the thickening unit at the distal end of the delivery wire.
[0023] The benefit of the delivery wire as disclosed in the following description is the fact that it prevents damage or rupture of one or more endothelial cell layers of the intracranial tortuous blood vessels during the deployment of the implant.
[0024] Now specifically referring to drawings, FIG.1 depicts the intracranial vessels referred to as the treatment site in an embodiment of the present disclosure. As is evident, the vessels include arteries and veins that are very tortuous and thus require a device with enough flexibility to pass through them without adversely impacting them.
[0025] FIG.2 depicts a placement device 100 and its various components. The length of the said placement device 100 ranges between 1700mm to 2300mm, more preferably 1900mm to 2100mm.
[0026] The placement device 100 includes one or more of, a delivery wire 101, a thickening unit 103, a polymeric tube 105, and a fluoro-safe marker 107.
[0027] The delivery wire 101 may be a conventional medical grade wire known to a person skilled in the art. The delivery wire 101 of the present disclosure is a thrust wire which is designed in an escalated pattern. In an embodiment, the material from which the delivery wire 101 is manufactured is a bio-compatible nitinol wire of (ASTM F 2063) grade. Alternately, the delivery wire 101 of the present disclosure may be made using an alloy that includes cobalt - chromium wires of grade L 605 (ASTM F -90).
[0028] Further, as depicted in FIG. 2, the said delivery wire 101 has two ends, a proximal end 101a and a distal end 101b. In an embodiment, the distal end 101b of the said delivery wire 101 is narrower as compared to the proximal end 101a of the delivery wire 101. The diameter of the proximal end 101a may range from 0.3mm-0.6mm. The diameter of the distal end 101b may range from 0.07-0.1mm. In an exemplary embodiment, the diameters of proximal end 101a and distal end 101b are 0.4mm and 0.08mm respectively. The length of the narrowed region is 400mm to 500mm, more preferably 430mm to 450mm while the length of the proximal end 101a is 1400mm to 1700mm, more preferably 1500mm to 1600mm.
[0029] As shown in FIG.2 of the present disclosure, the distal end 101b of the delivery wire 101 contains the thickening unit 103 (an enlarged view can be observed in FIG.2A). The said thickening unit 103 located at the distal end 101b of the delivery wire 101may include one or more devices but not limited to a tubing, a coil, and/or an additional element of wire. In an embodiment, the thickening unit 103 of the present disclosure is a coil (more clearly depicted in FIG. 2A of the present disclosure).
[0030] The said thickening unit 103 is any conventional coil that can be made up of a wire manufactured from a radiopaque alloy such as platinum, gold, iridium, tantalum, platinum-iridium or platinum-tungsten etc. Alternately, the thickening unit 103 may be made of a biocompatible alloy. The thickening unit 103 at the distal end 101b of the delivery wire 101 includes a helically wound filament having adjacent turns spaced apart by a preselected distance. The length of the thickening unit 103 may range from 25mm to 35mm but more preferably from 27mm to 32mm. The diameter of the thickening unit 103 ranges between 0.01mm to 0.13mm, more preferably 0.03mm to 0.08mm.
[0031] The coil disclosed in the present invention provides sufficient strength to the distal end 101b of the delivery wire 101. Further, during the deployment of the implant attached to the delivery wire 101 at the treatment site, the coil helps in transferring sufficient amount of thrust force and also prevents the kinking of the delivery wire 101 at its narrow distal end 101b. In addition, the radiopacity of the coil material helps in proper visualization and tracking of the implant while deployment in intracranial vessels. The thickening unit 103 disclosed in the present disclosure can be attached to the delivery wire 101 by any suitable means (depicted in FIG.2A in detail).
[0032] In the present invention as shown in FIG. 2 and more specifically an enlarged view can be seen in FIG. 2B of the present disclosure, the polymeric tube 105 may be provided over the delivery wire 101. In an embodiment, the polymeric tube 105 completely covers the distal end 101b of the delivery wire 101 including the thickening unit 103.
[0033] The said polymeric tube 105 may be made up of one or more materials like FEP (fluorinated ethylene propylene), polyolefin, polyimide, PET (Polyethylene terephthalate), polyurethane, etc. In an embodiment, the polymeric tube 105 is made up of PTFE (polytetrafluoroethylene).
[0034] The said polymeric tube 105 provides an efficient and swift placement of the delivery wire 101 at the treatment site. Additionally, the polymeric tube 105 disposed over the thickening unit 103 reduces the thrust force delivered by the delivery wire 101. The thrust force in the present invention refers to the force transferred from an external source say a physician or the user of the said placement device 100 to the deployable implant. The said delivery wire 101 transfers energy required to deploy the implant to the target location. The thrust force is reduced as it gets distributed over the polymeric tube 105 and the thickening unit 103. Further, given the polymeric tube 105 has low coefficient of friction, the thrust force required to push the thickening unit 103 is minimized.
[0035] The proximal end 101a of the delivery wire 101 includes one or more fluoro-safe markers 107 (enlarged view provided in FIG. 2C of the present disclosure). The said fluoro-safe markers 107 may be provided in a region of the delivery wire 101 that is not coated with any hydrophilic/plastic material. The length of the fluoro-safe marker 107 may range in between 20mm to 35mm, more preferably 25mm to 30mm.
[0036] The main function of the said marker 107 is to efficiently locate the implant at time of deployment and to keep a track on the movement of the delivery wire 101. The marker 107 helps to determine whether the delivery wire 101 has crossed carotid artery or not which in turn allows to ascertain if the implant has reached near the intracranial region.
[0037] The proximal end 101a of the delivery wire 101 may be coated with a plastic/hydrophilic coating. The said coating exhibits water-loving properties thus ensuring low coefficients of friction during deployment. The coating material may be applied on the said delivery wire 101 by various techniques like spraying, wiping, immersion, or other means, as long as appropriate measures are taken to provide proper coating thickness. The technique used in the present invention includes a dip coating method. Moreover, in an exemplary embodiment of the present invention, the complete placement device 100 can also be hydrophilic coated.
[0038] The hydrophilic coating material used for the above disclosed coating may be chemically modified polyester or polyurethane which may include, without limitation, sorin, phosphorylcholine, trillium, poly(2-methoxyethlacryalte), etc.
[0039] In an embodiment, the concentration of the coating composition is tabulated in the table below:
BASE COAT (100g) TOP COAT (100g)
PMA Poly(methyl acrylate) 50%– 80% Purified Water 78%–98%
Hyaluronic acid 1%–10% Hyaluronic acid 0.3%-2.3%
Crosslinking agent 0.1%-5% Sodium Hyaluronate 1%-14%
Aliphatic polyisocyanate 20%-40%

[0040] FIG. 4 depicts the placement device 100 carrying the implant. As mentioned above, the implant may include, but not limited to, a neurovascular coil, a clot retrieval device/revascularization device, a coil assisting device, a flow diverter, or any other neurovascular stent or stent or scaffold, etc. In an embodiment of the present disclosure, the implant attached to the placement device 100 is a stent. The said implant may be attached to the delivery wire 101 by one or more engagement members, for example, a pair of forceps.
[0041] Further, a method 400 for manufacturing and subsequently assembling the placement device 100 is depicted in the form of a flowchart disclosed in FIG.5.
[0042] At step 401 of the process, the delivery wire 101, (a having a diameter ranging from 0.20mm to 0.70mm, but more preferably 0.30mm to 0.60mm is selected. In an embodiment, the delivery wire 101 is a raw nitinol wire with specific characteristics and physical properties)
[0043] Further, at step 402, the delivery wire 101 is machined/laser cut/ processed in order to render the delivery wire 101 a tapered configuration. In an embodiment, tapering is performed using a CNC (computer numerical control) lathe machine. However, the use of any other conventional machine for tapering the delivery wire 101 is also within the scope of the present invention.
[0044] At step 403, passivation of the said tapered delivery wire 101 is performed. Passivation may be performed in one or more cycles. In an embodiment, the no. of passivation cycles range between5 to 10 cycles.
[0045] At this step, the delivery wire 101 is immersed in a vessel containing a passivation solution. In an embodiment, the passivation solution includes 30-35% of nitric acid in water maintained at 40-45°C. An agitator is placed in the vessel for constantly stirring the passivation solution. The rotational speed of the agitator may be of 350-400 rpm. The time duration of each passivation cycle may be 20-40 mins. Each passivation cycle is followed by sonication of the delivery wire 101 in a sonicator containing de-ionized water. The sonication cycle runs for 20-30minutes after each passivation cycle.
[0046] Further, at step 404, the thickening unit 103 is attached to the delivery wire 101 at its distal end 101b. The thickening unit 103 is attached by welding (like, spot welding) or bio-compatible adhesives. In case, the attachment of the thickening unit 103 is performed by spot laser welding, a laser welding probe 109 (depicted in FIG. 3) is used to generate a pulse width ranging from 0.1ms (microseconds) to 1.0ms, more preferably from 0.4ms to 0.6ms. The welding spot diameter ranges from 0.10mm to 0.30mm, more preferably from 0.17mm to 0.23mm. The amount of power provided for the said welding procedure ranges from 220V to 260V, more preferably from 235V to 245V.
[0047] The biocompatible adhesives may include, without limitation, dymax, loctite, etc.
[0048] At step 405, after attachment of the thickening unit 103 at the distal end 101b, the thickening unit 103 is provided with the polymeric tube 105as depicted in FIG. 2B of the present disclosure.
[0049] At step 407, the proximal end 101a of the delivery wire 101 is coated with the plastic/hydrophilic coating. Alternately, any other surface of whole placement device 100 may be coated with the plastic/hydrophilic coating. In an embodiment, the method of coating is performed in a reservoir or a dip coating machine. The method for coating the said delivery wire 101 involves a process in which one or more wires 101 are inserted in a PTFE solution for 01minute to 06minutes, more preferably 02minutes to 05minutes and further transferred to UV curing machine.
[0050] Single or multiple coats can be applied on the delivery wire 101 using one or more coating methods. However, in an embodiment of the present invention, two successive coats are applied on the wire by performing two cycles of the above mentioned process. After the coating process, the delivery wire 101 is uniformly exposed to UV light for curing. The said wire is exposed for 02 minutes to 07 minutes but more preferably 04minutes to 05minutes.
[0051] The present invention and its advantages will now be supported by way of various examples:
EXAMPLES:
[0052] Example 1 (prior art): A delivery device i.e. simply a wire or guide-wire used conventionally to deploy any retrievable device at a target location was utilized in the present example a simple (stainless steel 304V) wire is used for in-vitro testing to deploy a retrievable device at a neurovascular region i.e. MCA segment. An in-vitro model illustrating cerebral vasculature was specially developed for testing, the said model comprised of silicon vessels that imitated the functioning and structure of natural cranial vasculature. Various factors affecting deployment and retrieval of the device were evaluated i.e. track force, push efficiency. During in-vitro evaluation, it was observed that the wire required higher thrust force to deploy the retrievable device and push efficiency was also less. Additionally, it was observed that the wire was also kinked at many regions. Along with the above mentioned issues, it was analyzed that due to higher friction the said wire also injured the targeted vessels or endothelial layer of vessels. Hence, the SS wire could not be used in tortuous anatomy like M-3 (MCA) segment, cavernous structure and other complex DVT interventional techniques.
[0053] Three trials were performed with Stainless steel (304V) made delivery wire and subsequently their thrust force was analyzed. The analysis is tabulated below:
SR# Material of construction Wire Diameter
(mm) No. of trials Maximum Force(N)
1 Stainless steel(304V) 0.4 Trial 1 1.36
2 Stainless steel(304V) 0.4 Trial 2 1.25
3 Stainless steel(304V) 0.4 Trial 3 1.40
[0054] Example 2: In the present example, a tapered nitinol wire was utilized instead of SS wire for all the interventional techniques especially in tortuous neuro vasculature. To overcome the complex tortuosity, tapering was done at the distal end of the said delivery wire and coil was attached on the distal tapered region of the nitinol wire. The said coil was a closed pitch platinum/iridium coil and was placed towards the distal region i.e. 5mm away from distal end of the delivery wire. The length of the coil that covered the delivery wire was 31mm, which provided resistance against kink to the wire at its tapered end. The diameter of the coiled region was 0.3mm. The diameter of the tapered delivery wire ranges from 0.4mm to 0.08mm as it get narrower from its proximal end towards distal end. A PTFE tube was heat shrunk over the coil once the coil was attached to the delivery wire. The diameter and thickness of the PTFE tube used for attachment to the coil was 0.4mm and 0.06mm. After the placement of the heat shrink tube over the coil the complete delivery wire was additionally coated with hydrophilic material. During in-vitro evaluation, it was observed that the said nitinol delivery wire required less thrust force and high push efficiency was observed to deploy the retrievable device. Repeatedly, three observations were taken for the values of the force exerted on the tapered delivery wire as tabulated below:

SR# Material of Construction Diameter of
Tapered Wire
(mm) No. of Trials Maximum Force(N)
1 Nitinol 0.4-0.08 Trial 1 0.39
2 Nitinol 0.4-0.08 Trial 2 0.53
3 Nitinol 0.4-0.08 Trial 3 0.48

[0055] Thus from the above observations it is concluded that the tapered nitinol wire of the present invention requires significantly less force compared to conventional wires thus reducing trauma for patients.
[0056] 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.