Claims:WE CLAIM:
1. A medical device (100) for breaking up thrombus or other obstructive material, the device comprising:
a. a soft tip (107);
b. a core wire (101) having a distal end (101b), the distal end (101b) including a working portion (101a’), the working portion (101a’) being made of a flexible material and is shape set to attain a sinusoidal shape, the working portion (101a’) of the core wire (101) being tapered;
c. a coiled wire (103) mounted over the core wire (101) to provide kink resistance, the coiled wire (103) being a single wire coiled over the core wire (101) resulting in reduced stiffness of the device; and
d. a socket (105) provided at the distal end (101b) of the core wire (101) to connect the soft tip (107) to the core wire (101).
2. The medical device (100) as claimed in claim 1 wherein the medical device (100) includes a tube on the coiled wire (103).
3. The medical device (100) as claimed in claim 2 wherein the tube includes a polymeric heat shrink tube (111).
4. The medical device (100) as claimed in claim 1 wherein the medical device (100) includes an abrasive coating layer (113) on the coiled wire (103).
5. The medical device (100) as claimed in claim 4 wherein the abrasive coating (113) includes diamond abrasives at least partially coated with a thin layer of nickel.
6. The medical device (100) as claimed in claim 1 wherein the socket (105) is oblong shaped.
7. The medical device (100) as claimed in claim 1 wherein the core wire (101) is made of nitinol.
8. The medical device (100) as claimed in claim 1 wherein the coiled wire (103) is made of nitinol. , 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:
MEDICAL DEVICE FOR REMOVAL OF PLAQUE AND METHOD OF PREPARATION THEREOF

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

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 device and method of manufacturing thereof. More specifically, the present invention relates to a medical device used for removal of calcified plaques, hard blood clumps and/or thrombus from peripheral arteries.
BACKGROUND
[002] Atherosclerosis is one of the major diseases that are caused by the accumulation of plaque inside a person's vasculature. Plaques can be deposited in various forms like fat, cholesterol, calcium, and other substances found in the blood, etc. Over time, the accumulated plaque may result in a partial or total occlusion of one or more blood vessels resulting in coronary artery disease, peripheral vascular disease, and/or cerebral vascular disease, kidney failures, etc.
[003] Another major cause of blood vessel occlusion is the formation of blood clumps or thrombus in the blood vessels (i.e. arteries or veins). Arterial disease in particular, causes severe problems to people suffering from diabetes, high blood pressure, high cholesterol, etc. More specifically, blockage of arteries results in hypertension, leg pain, swelling, redness in the skin, causing deep vein thrombosis (DVT).
[004] A lot of treatment strategies for curing the blockage or removal of plaques and blood clots or thrombus have been suggested/devised, however, removing plaques or clots from the arteries such as, coronary arteries, iliac artery, femoral artery, pulmonary artery, carotid etc, still remains challenging due to high risk of vasculature damage during the insertion of any thrombus or plaque removal device inside the blood vessels.
[005] Currently available approaches for removal of blood clot, thrombus or plaque include balloon angioplasty, endarterectomy, etc. Additionally, some other forms of treatment include food and dietary supplements, like various therapeutic agents that may be inserted or injected in the blood vessels. These agents include thrombolytic agents i.e. urokinase or streptokinase. The said agents or techniques exhibit limitations by merely dilating the blocked blood vessels or slowing down the progression of plaque or thrombus formation. Additionally, these medications causes risk of drug toxicity and severe bleeding as the clots or plaques are not removed completely rather, crushed.
[006] Apart from the above, various thrombectomy and atherectomy devices are conventionally known. However, such devices lack flexibility when placed in long, tortuous blood vessels, and further lacks in macerating hard thrombus and/or plaque.
[007] For example, the patent publication, US8475487B2 discloses “a thrombectomy catheter with flexible and expandable cage for removal of hardened and aged thrombotic material”. Though the provided reference discloses a thrombectomy device, the said reference uses a thrombectomy catheter with a flexible and expandable cage.
[008] Another prior art US20140288583A1 discloses “Vascular plaque removal systems, devices, and methods” the said invention includes a catheter body and a dissection tip.
[009] Further, above mentioned prior arts involve two separate devices for the removal of plaque as well as thrombus. Therefore, there arises a requirement of a single device that can be used for removal of soft blood clumps and plaque. Additionally, the above mentioned prior arts lack abrasive coating for plaque removal that acts as atherectomy device. The said system should overcome the aforementioned challenges associated with the conventional treatment systems.
SUMMARY
[0010] The present invention relates to a medical device for breaking up thrombus or other obstructive material. The device includes a soft tip, a core wire, a coiled wire and a socket. The core wire includes a distal end having a working portion. The working portion is made of a flexible material and is shape set to attain a sinusoidal shape. The working portion of the core wire is tapered. A coiled wire is mounted over the core wire, to provide kink resistance. The coiled wire is in the form of a single wire which is coiled over the core wire resulting in reduced stiffness of the device. A PTFE/FEP tube or an abrasive coating may be provided on the coiled wire. The abrasive coating may include diamond abrasives at least partially coated with a thin layer of nickel. A socket is provided at the distal end of the core wire to connect the soft tip to the core wire.
BRIEF DESCRIPTION OF DRAWINGS
[0011] 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.
[0012] FIG. 1 depicts a medical device being deployed at an implantation site in accordance with an embodiment of the present invention.
[0013] FIG. 1a depicts the complete assembly of the medical device in accordance with an embodiment of the present invention.
[0014] FIG. 2 represents core wire with the coiled wire wound on the core wire in accordance with an embodiment of the present invention.
[0015] FIG. 2a depicts the FEP heat shrink wrap over the coiled wire, in accordance with an embodiment of the present invention.
[0016] FIG. 3a-3c show different embodiments of abrasive coating layer provided over the coiled wire, in accordance with an embodiment of the present invention.
[0017] FIG. 4a illustrates an exemplary embodiment carrying the heat shrink PTFE tube over the core wire in accordance with an embodiment of the present invention.
[0018] FIG. 4b shows an exemplary embodiment carrying abrasive coating over the core wire in accordance with an embodiment of the present invention.
[0019] FIG. 5a depicts the sinusoidal shape of the coiled wire in accordance with an embodiment of the present invention.
[0020] Fig. 5b depicts the sinusoidal shaped coiled wire in accordance with an embodiment of the present invention.
[0021] FIG. 6 illustrates a flowchart depicting steps involved in the manufacturing and assembling of the medical device in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] It should be noted that the term ‘diameter’ in the following description corresponds to outer diameter until and unless specified otherwise.
[0027] In accordance with the present disclosure, a medical device is disclosed. The said medical device may function both as a thrombectomy as well as atherectomy device. The medical device disclosed in the present invention may be a rotatory thrombectomy device being capable of breaking hard clumps and/or plaques and further removing the plaque, clot and/or thrombus from an implantation site. The medical device may also be capable of ablation post removing the clots. The implantation site of the present disclosure may include one or more occluded/calcified blood vessels including coronary artery, iliac artery, femoral artery, pulmonary artery, etc.
[0028] The medical device of the present invention may be a guide wire based device and does not require any other additional device for guiding purpose.
[0029] The medical device of the present invention includes a core wire (or wire) having a distal end. The core wire includes a working portion and a non-working portion. The working portion is disposed towards the distal end of the core wire. The core wire may be tapered from a pre-defined location on the non-working portion up to the distal end of the core wire. Such tapering reduces stiffness and increases flexibility of the core wire. As a result, torque required to rotate the medical device is reduced due to enhanced flexibility. Hence, the tapered core wire of the present invention allows can easy penetration of the medical device into the highly calcified and occluded vessels.
[0030] The working portion as well as the non-working portion may be wrapped with at least one coiled wire (preferably, a single coiled wire) having tight pitch coiling. The use of a single coiled wire results in reduction of stiffness in the medical device thereby conferring flexibility of the same. The working portion along with the coiled wire includes a pre-defined shape, for example, a sinusoidal shape. The said shape is selected to suit the tortuous vascular anatomy.
[0031] The coiled wire at the working portion may be completely or partially covered with a heat shrink tube, for example, fluorinated ethylene propylene. The coiled wire having a heat shrink tube over it prevents lumen damage during surgery for braking of soft clumps.
[0032] Alternately, the coiled wire at the working portion may include an abrasive coating. The abrasive coating may include diamond abrasives coated with a thin layer for example, nickel layer for better and firm placement of diamond abrasives over the periphery of the coiled wire and safety of endothelial layer of the vessel.
[0033] The abrasive coating over the coiled wire helps to remove hard-plaques from the occluded and calcified vessel.
[0034] Additionally, the medical device preferably includes a socket disposed at the distal end of the core wire. The socket is structured as an oblong shaped ball. The said socket provides firm placement of an atraumatic tip and further prevents migration/dislocation of the same during procedure. Moreover, the presence of the said socket restricts change in a central rotational axis during rotational motion of the medical device.
[0035] Now referring to figures, FIG.1 illustrates an exemplary embodiment of the medical device 100 of the present disclosure being implanted at an implantation site. The implantation site may be any blocked vessel in one of, pulmonary artery, iliac artery, coronary artery, femoral artery, artificial grafts etc. The medical device 100 may be placed within the blocked vessel to remove clot, plaque or thrombus, etc. as shown in FIG. 1. In an embodiment, the medical device 100 is implanted with a debris collector/filter unit 109. The debris collector /filter unit 109 is utilized to collect debris of calcified materials and prevents the debris from reaching the heart/brain. A multi-loop coiled tapered radio-opaque wire is designed for various lumen diameters that range from for example, 0.018’’ to 0.044”.
[0036] As represented in FIG. 1a, the medical device 100 may include various components (as described below) which are disposed along a longitudinal axis ‘a’. The medical device 100 may include a core wire 101. The core wire 101 of the present invention may be made of a conventional medical grade material known to a person skilled in the art. The core wire 101 may be made of one or more materials but not limited to stainless steel, CoCr (cobalt-chromium), nitinol etc. In an embodiment, the core wire 101 is made of nitinol.
[0037] The core wire 101 may include two ends i.e. a proximal end 101a and a distal end 101b. The proximal end 101a of the core wire 101 includes a non-working portion 101a’ while the distal end 101b includes a working portion 101b’. The non-working portion 101a’ may be utilized for providing sturdiness and strength to the core wire 101. The non-working portion 101a’ may be linearly disposed along the longitudinal axis ‘a’. The non-working portion 101a’ helps to generate vortex effect due to its rotational motion. The working portion 101b’ may correspond to an active section which participates in breaking the plaques/clots/thrombus (via vortexing). The working as well as the non-working portion 101a’ may include at least one coiled wire 103 wrapped over the core wire 101 (described below).
[0038] The length of the non-working portion 101a’ may range between 550 mm to 650 mm and/or 1250 mm to 1350 mm. In an embodiment, the length of the non-working portion 101a’ is 580 mm and/or 1280 mm. The non-working portion 101a’ may include a uniform diameter. The diameter of the non-working portion 101a’ may range between 0.5 mm to 1.3 mm and/or 0.9 mm to 1.5 mm. In an embodiment, the diameter of the non-working portion 101a’ is 0.90 mm and/or 1.12 mm. In an embodiment, the core wire 101 tapers from a pre-defined location on the non-working portion 101a’ of the core wire 101 up to the distal end 101b of the core wire 101. The pre-defined location may be 60-90mm towards proximal end 101a from the soft tip 107 to the distal end 101b of the core wire 101. The diameter of the pre-defined location may range between 0.8 mm to 1.5 mm. In an embodiment, the diameter of the pre-defined location is 0.9 mm. Owing to the above tapering, the working portion 101b’ may include a completely tapered configuration. The diameter of the distal end 101b may range from 0.09 mm to 0.90 mm. In an exemplary embodiment, the diameter of the tapered distal end 101b is 0.6 mm.
[0039] The length of the working portion 101b’ may range between 50 mm to 80 mm. In an embodiment, the length of the working portion 101b’ is 60mm.
[0040] In an exemplary embodiment, the working portion 101b’ of the medical device 100 may include a pre-defined shape. The pre-defined shape may include sinusoidal shape, cage like shape, c-shape or multi-wire with wave shape. In an embodiment as represented in FIG. 1a, the shape of the working portion 101b’ is sinusoidal namely, having two peaks placed adjacently in opposite directions. In an embodiment, the peak to peak distance is 9mm and/or 15mm, therefore, the peak distance of each peak from the longitudinal axis ‘a’ is equal on both sides i.e. 4.5mm and/or 7.5mm resulting in minimum fluctuation of the core wire 101 from the longitudinal axis ‘a’.
[0041] The width “C” of the working portion 101b’ having a sinusoidal shape may range from 3mm to 10mm. The purpose of having a sinusoidal shaped working portion 101b’ is to provide enhanced flexibility and fluctuation balance during the functioning of medical device 100 inside the tortuous vasculature.
[0042] In an embodiment, the working as well as the non-working portions 101a’ includes a single coiled wire 103 which is helically wound over the core wire 101. The coiled wire 103 may include tightly pitched turns as shown in FIG. 2. The coiled wire 103 may be bonded/welded to the core wire 101 at its ends. The coiled wire 103 may be any conventional coil that can be made up of a wire manufactured from one or more materials including stainless steel, CoCr (cobalt-chromium), nitinol, platinum-tungsten alloy, platinum-iridium alloy, etc. In an embodiment, the coiled wire 103 is made of nitinol. The length of the coiled wire 103 may range from 650 mm to 1350 mm. The diameter of the coiled wire 103 ranges between 0.20mm to 0.30mm and more preferably 0.25mm to 0.30mm.
[0043] The coiled wire 103 disclosed in the present invention provides sufficient strength to the core wire 101. Further, during the plaque, clot or thrombus removal from the implantation site, the coil helps in transferring sufficient amount of thrust force and also prevents the kinking of the core wire 101. Push force is uniformly distributed over coiled wire 103 because of frictional force acting between core wire 101 and coiled region of non-tapered wire thereby preventing kinking. Also, due to tapered configuration of the working portion 101b’, the sinusoidal shaped wire is flexible for easy navigation through tortuous anatomy. Further, during the thrombectomy/atherectomy procedure, flexibility of the core wire 101 renders smooth functioning without any damage to endothelial layer of the treatment site.
[0044] In an exemplary embodiment as illustrated in FIG.2a, a tube 111 may be provided over the coiled wire 103. In an embodiment, the tube 111 is a polymeric heat shrink tube. The tube 111 may be made up of one or more materials like FEP (fluorinated ethylene propylene), PTFE (polytetrafluoroethylene), PET (Polyethylene terephthalate), polyolefin, polyvinyl chloride, etc. In an embodiment, the tube 111 is made up of FEP (fluorinated ethylene propylene). The tube 111 provides an efficient and swift insertion of the medical device 100 during the removal of blood clumps from the blood vessels.
[0045] In another embodiment of the present invention, the coiled wire 103 of the working portion 101b’ is provided with an abrasive coating layer 113 to remove hard calcified plaque or hard thrombus deposited in the tortuous blood vessels. The said abrasive coating layer 113 includes one or more metal crystals like brass, diamond, gold, silver, tin, zinc, copper, cadmium, chromium, nickel, platinum, lead, etc. In an embodiment of the present invention, nickel and/or diamond or brass is used. The said metal crystals are coated partially or completely with one or more compounds including nickel, cobalt, zinc, copper, platinum, lead, etc.
[0046] In an exemplary embodiment as shown in FIG. 3a, the abrasive coating layer 113 having diamond abrasives 113a coated with a thin nickel layer 113b, is provided over the coiled wire 103 for better and firm placement of the diamond abrasives 113a and safety of endothelial layer of the vessel. Other embodiments of the abrasive coating layer 113 as provided over the coiled wire 103 have been depicted in FIGs. 3b-3c of the present invention. In FIG. 3b, the abrasive coating layer 113 includes diamond abrasives 113a partially coated with a thin nickel layer 113b. Alternately, an abrasive coating layer 113 having non-coated diamond abrasives may also be provided as shown in FIG. 3c.
[0047] The abrasive coating layer 113 present on the coiled wire 103 of the working portion 101b’ is further provided by one or more techniques including electro-deposition, (elaborated in detail below), sedimentation, electro-polishing, etc.
[0048] The pre-electrodeposited layer 113a’ and an electrodeposited layer 113b’ over the coiled wire 103 have been depicted in FIGs. 3a-3c.
[0049] In another embodiment, multiple wires may be coated with an abrasive coating layer 113 or polymeric heat shrink tube 111 can be utilized for shredding plaque or blood clumps as shown in (FIGs. 4a and 4b).
[0050] Further, the distal end 101b of medical device 100 may include a socket 105 as (depicted in FIGs. 5a and 5b) for placement of a soft tip 107 (or atraumatic tip). In an embodiment as shown in FIG. 5a, the socket 105 is an oblong shaped solid ball type structure. The socket 105 helps to provide firm placement of the soft tip 107 and prevents dislocation of the same during the functioning of the medical device 100. In an alternate embodiment, the socket 105 can also be utilized as a soft tip 107 due to its atraumatic geometry.
[0051] The soft tip 107 may be made of a radiopaque material. The said soft tip 107 may be made of one or more polymeric materials including PEBAX, nylon, silicon, PET or any other polyamide material. Moreover, due to attachment of ball shaped socket 105, the central rotational axis is not changed during rotational motion of the device. The attachment of the socket 105 adds more weight on the longitudinal axis ‘a’ thereby acting as a pivot during the rotational motion of the core wire 101.
[0052] The said soft tip 107 is flexible in nature and is designed in such a manner that maintains the equilibrium balance of the core wire 101 carrying the coiled wire 103 from the longitudinal axis ‘a’ of the medical device 100.
[0053] Further a method 400 for manufacturing and subsequently assembling the medical device 100 is depicted in the flowchart disclosed in FIG. 6.
[0054] At step 401 of the process, the core wire 101, (having a diameter ranging from 0.3 to 0.8mm) is selected. In an embodiment, the delivery wire is a raw nitinol wire with specific characteristics and physical properties.
[0055] Further, at step 402, the core wire 101 is tapered by machining on laser cutting, CNC (Computer Numerical Control) lathe machining or EDM (Electrical Discharge Machining). The dimensions of the core wire 101 can referred from the preceding paragraphs.
[0056] At step 403, the coiled wire 103 is attached or wound onto the core wire 101 at its distal end 101b. Optionally, the said coiled wire 103 may be attached to the proximal end 101a of the core wire 101. The coiled wire 103 is attached by welding (like, spot welding) or biocompatible adhesives. In case, the attachment of the coiled wire 103 is performed by spot laser welding, a laser welding probe (Not shown in figures) is used to generate a pulse width ranging from 0.5 ms to 1.5 ms.
[0057] The biocompatible adhesives may include, without limitation, cyano-acrylate, epoxy, urethane acrylate, etc.
[0058] At step 404, after the coiling process, shape setting (as depicted in FIG’s. 5a and 5b.) of the distal end 101b of the coiled wire 103 placed over the core wire 101 is performed by tightly placing the distal end 101b of the core wire 101 over the mandrel or fixture of desired shape. In an exemplary embodiment, the desired shape of the distal end 101b of the coiled region is sinusoidal. Further, heating of the said coiled wire 103 is performed at temperatures ranging from 500°F to 1300°F and more preferably 900°F to 1000°F for 02 minutes to 20 minutes more preferably from 05 minutes to 10 minutes. Subsequently, cooling of the sinusoidal shaped wire 101 is performed by water, oil, inert gas, cool air, etc and the mandrel is removed. Higher heating will increase actuation temperature of the part and often gives a sharp thermal response thus minimizing the ability of the nitinol wire to resist permanent deformation. The extreme distal end 101b of the core wire 101 is a straight wire to provide an attachment point for the soft tip.
[0059] Additionally, aluminum oxide sand is sprinkled over the sinusoidal shaped wire 101. Alternately, aluminium oxide is filled in a fluidized bath as a medium for thermal transfer and heat is radiated into the sand either directly or indirectly from the heaters. Air may be constantly provided in the bath which plays a key role in stirring the heated sand to give consistent and stable thermal results.
[0060] Further, at step 405, electro-polishing of the sinusoidal shaped medical device 100 may be performed during which the distal end 101b of the core wire 101 is dipped in one or more electrolytes and/or acids with high viscosity, such as sulphuric acid and phosphoric acid, etc. Electrolyte is a mixture of per chlorates with acetic anhydride and methanolic solution of sulphuric acid. In the present invention, the mixture of acetic acid and perchloric acid is used.
[0061] Electropolishing of the sinusoidal shaped portion of the coiled wire 103 is performed in an electropolishing machine. The said process is performed to obtain a polished surface without any debris over the sinusoidal shaped coil wire 103. In an embodiment of the present disclosure, a mixture of acetic acid and perchloric acid in concentrations of 78% and 22% respectively are used. The said mixture is placed in a beaker with copper plates provided as cathode and the wire to be electropolished is placed as anode mounted in an up-right position (sinusoidal shaped portion dipped in electrolyte) with the help of a holder. Further, an appropriate voltage and current in the range from 5 to 12 volts more preferably 7 to 12 volts and current 0.3 to 1.5A more preferably 0.6 to 1.2A is provided in the said beaker through an external source like battery, other power supply means, etc. The above mentioned step is repeatedly performed in cycles (each cycle lasts for 2 min to 5 min) say 2 to 4 times till the desired thickness of 0.9mm or polishing is achieved. In an exemplary embodiment of the present invention, electropolishing is performed in 3 cycles for 1 minute each at 9V and 0.9A.
[0062] Post electropolishing step, depending on the type of blockage to be removed say, plaque or blood clumps at step 406, the said sinusoidal shaped distal end 101b of the wire may be provided with a polymeric heat shrink tube 111 and/or an abrasive coating layer 113. In an exemplary embodiment, a FEP (fluorinated ethylene propylene) heat shrink tube 111 is provided over the coiled wire 103 as depicted in FIG. 2a of the present disclosure. Alternately, any other surface of whole core wire 101 may be covered with a heat shrink polymeric tube 111.
[0063] In an embodiment, the method of providing a FEP (fluorinated ethylene propylene) heat shrink tube 111 is performed via hot air provided through a hot air gun device for 10 minutes, more preferably for 5 minutes.
[0064] In another embodiment, the coiled wire 103 may be alternately provided with an abrasive coating layer 113 (depicted in FIG.3b). The said abrasive coating is performed via electro-deposition process, performed in a vessel. The vessel is equipped with nickel which acts as an anode and additionally, coiled wire 103 to be coated acts as a cathode. Further, current intensity of 1 to 15 A/dm2 is provided in the solution for 30 seconds to 2 minutes.
[0065] The abrasives referred to as diamond crystals/powder in the form of slurry (Diamond crystals are added in the form slurry to the electrolyte) are provided in the vessel containing electrolyte solution which contains one or more electrolytes like nickel sulphate, nickel chloride and boric acid. In an exemplary embodiment of the present disclosure, a mixture of nickel sulphate, nickel chloride, boric acid and diamond powder is used in the concentrations of 250 grams/lit, 30 grams/lit, 450 grams/lit and 5 grams/lit respectively.
[0066] Additionally, to lower the surface tension of the solution and to facilitate release bubbles formation, an anti-pittng agent say, sodium lauryl sulphate in 0.01 grams/lit concentration is added in the electrolyte mixture.
[0067] Further, to improve the uniformity of the dispersed diamond powder/crystals cobalt in 2.99% concentration is added in the mixture of the vessel and the said mixture is gently stirred with a stirrer mounted over the vessel.
[0068] At step 407, the bonding of the soft tip 107 to the connector attached at the distal end 101b of the core wire 101 is performed by adhesive boding (depicted in FIG’s. 5a and 5b). Though the description elaborates the adhesive bonding process in particular, other types of bonding methods like mechanical bonding, chemical bonding, shrink bonding, etc may also be utilized for attachment of the soft tip 107 of the present invention. In an exemplary embodiment, chemical bonding is preferred i.e. adhesive bonding with ultraviolet curing.
[0069] At step 409, the core wire 101 is assembled with a rotatory device handle. The said handle includes a motor to rotate the wire.
Examples:
[0070] Example 1 (Prior art): The core wire having a non-tapered stranded wire with a nitinol wire coiled over the core wire was used as a medical device for removal of calcified plaque from the clogged femoral artery or any peripheral artery. The core wire along with the coiled wire exhibited a sinusoidal shape. The nitinol wire had a diameter of 0.3mm. The length of the nitinol coiled wire was 650mm. The nitinol coiled wire was further coated with diamond abrasives (without any pre-deposited layer/non-coated abrasives). The diameter of the coated, sinusoidal shaped wire was found to be 1.12mm. Further, a soft tip was attached by crimping the soft tip over the core wire.
[0071] Furthermore, the multi-point bending test was performed on the core wire thus requiring a force of 1.750 Newton for bending. The test results implied that the wire used in Example 1 was stiffer and lacked flexibility during insertion in the tortuous anatomy. Post deployment of the said medical device at the implantation site, it was found that the soft tip was dislocated during the functioning of the medical device. It was observed that the stranded non-tapered core wire of Example 1 had reduced flexibility during the maceration of the blood clot.
[0072] Example 2 (Present invention): The core wire having a single tapered wire with a nitinol wire coiled over the core wire was used as a medical device for removal of calcified plaque from the clogged femoral artery or any peripheral artery. The core wire along with the coiled wire exhibited a sinusoidal shape. The nitinol wire had a diameter of 0.3mm. The length of the nitinol coiled wire was 650mm. The nitinol coiled wire was further coated with diamond abrasives with a pre-deposited nickel layer as described in the present invention.
[0073] Further, the attachment of the soft tip was performed by attaching an oblong shaped socket or connector at the distal end of the core wire. The said oblong shaped socket provided a firm attachment of the soft tip to the core wire during maceration. The multi-point bending test was carried out on the exemplified wire, and it was observed that a maximum force of 0.09 Newton was required for achieving bending of the wire. The bending test performed above implied to reduced stiffness and increased flexibility of the core wire. As a result, torque required to rotate the medical device is reduced due to enhanced flexibility.
[0074] 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.