Claims:We claim:
1. A retrieval device comprising:
a core member;
at least three grasping arms coupled to the core member, each of the at least three grasping arms comprising:
at least one stem having a distal end and a proximal end, the proximal end of the at least one stem being connected to the core member,
at least two prongs, each of the at least two prongs having a distal end and a proximal end, the proximal end of each of the at least two prongs being connected to respective distal end of the stem; and
a plurality of extension members, each extension member being coupled to the distal end of the at least two prongs.
2. The retrieval device as claimed in claim 1 wherein the plurality of stems is arranged equidistantly in a circumferential manner.
3. The retrieval device as claimed in claim 1 wherein the at least one stem is inclined at an angle ranging from 90° to 130° with respect to the core member.
4. The retrieval device as claimed in claim 1 wherein angle between the at least two prongs ranges from 5° to 50° with respect to each other.
5. The retrieval device as claimed in claim 1 wherein the at least two prongs are coupled to the at least one stem in one of a V- shaped or U-shaped configuration.
6. The retrieval device as claimed in claim 1 wherein each of the extension members is perpendicular to the distal end of the respective prong.
7. The retrieval device as claimed in claim 1 wherein, the proximal end of each of the at least two prongs is coupled to the distal end of the respective stem at an angle ranging from 150° to 160°.
8. The retrieval device as claimed in claim 1 wherein the core member, the at least one stem and the at least two prongs are disposed along a longitudinal axis.
9. The retrieval devices as claimed in claim 1 wherein a plurality of radiopaque markers are provided on at least one of the at least three grasping arms.
10. The retrieval devices as claimed in claim 9 wherein the plurality of radiopaque markers ranges from two to twelve.
11. The retrieval devices as claimed in claim 1 wherein the at least three grasping arms are partially or wholly coated with a coating or a knitted mesh. , 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:
RETRIEVAL DEVICE

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

3. 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, the present invention relates to a retrieval device for retrieving an object within a vasculature of a body.
BACKGROUND
[002] For many years, physicians have been placing various devices within a blood vessel of the human body in order to treat an aneurysm or to occlude a vessel by promoting thrombus formation. Such devices include dilatation balloons, stents, embolic coils, etc. In certain instances, an embolic coil, a stent or a clot must be removed from the vessel, repositioned or replaced. One known procedure for embolic coil, stent or clot removal is surgically removing the device from the vessel. However, this method can be time-consuming and traumatic to the patient.
[003] The development of flexible medical instruments has made it possible to remove embolic coils, stents and/or clots using minimally invasive surgical procedures. Currently, for treatment of aneurysm or to remove a foreign object from a patient’s vasculature, a retrieving device is used.
[004] A retrieval device includes a plurality of arms which help to grasp a targeted object (any embolic coil, stent and/or clot). However, the conventionally available retrieval devices fail to provide adequate grip to hold the targeted object. Such insufficiency may result in detachment of the targeted object from the retrieval device while it is retrieved back from the human body.
SUMMARY
[005] The present invention discloses a retrieval device. The retrieval device includes a core member and at least three grasping arms. The at least three grasping arms includes at least one stem, at least two prongs and a plurality of extension members. The at least one stem has a distal end and a proximal end. The proximal end of at least one stems is connected to the core member. The at least two prongs have a distal end and a proximal end. The proximal end of the at least two prongs is connected to distal end of the respective stem. Further, the plurality of extension members is coupled to the distal end of the at least two prongs.
BRIEF DESCRIPTION OF THE DRAWINGS
[006] 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
[007] FIG. 1 illustrates a retrieval device in an expanded state in accordance with an embodiment of the present invention.
[008] FIG. 1a illustrates the retrieval device 100 in a compressed state in accordance with an embodiment of the present invention.
[009] FIG. 1b illustrates the top view of the retrieval device 100 in accordance with an embodiment of the present invention.
[0010] FIG. 1c illustrates the retrieval device 100 with a coating in accordance with an embodiment of the present invention.
[0011] FIG. 1d illustrates the retrieval device 100 covered by a mesh in accordance with an embodiment of the present invention.
[0012] FIG. 2 illustrates an alternate embodiment of the retrieval device 100 in expanded state in accordance with an embodiment of the present invention.
[0013] FIG. 2a illustrates the retrieval device of FIG. 2 in compressed state in accordance with an embodiment of the present invention.
[0014] FIG. 2b illustrates the top view of the retrieval device 100 in accordance with an embodiment of the present invention.
[0015] FIG. 2c illustrates the retrieval device 100 with a coating in accordance with an embodiment of the present invention.
[0016] FIG. 2d illustrates the retrieval device 100 covered by a mesh in accordance with an embodiment of the present invention.
[0017] FIG. 3 represents the process of manufacturing the retrieval device 100 in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] 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.
[0019] 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.
[0020] In accordance with the present disclosure, a retrieval device is disclosed. The retrieval device is used for capturing a targeted object(s) trapped inside patient’s vasculature anatomy. The retrieval device of the present invention is capable of capturing/retrieving objects like, without limitation, an aneurysm coil, a blood clot (thromboembolism), a metal debris, etc.
[0021] The retrieval device of the present invention may be fabricated from a durable material known in the art. For example, the retrieval device is fabricated by laser cutting of a nitinol tube.
[0022] The retrieval device includes multiple grasping arms supported on a core member. For example, the grasping arms may be three to six in number. In an embodiment, the grasping arms are arranged equidistantly in a circumferential manner. Each grasping arm of the present invention has a structure similar to a multi-pronged fork. The presence of a multi-pronged fork structure provides enhanced strength to the retrieval device for capturing and holding a targeted object and reduces any chance of slippage of the targeted object while capturing the same.
[0023] In an embodiment, each grasping arm includes two prongs and a stem. For example, the retrieval device that includes three grasping arms contains six prongs and three stems in total which provide better grip and easy entrapment of the targeted object.
[0024] Further, the two prongs of a grasping arm may make an angle ranging from 5° to 50° with each other. The said angle prevents jumbling of prongs and helps to provide optimum radius to the device in the expanded state, increasing its capturing efficiency.
[0025] Further, the grasping arms of the retrieval device may be partially or wholly coated with a non-degradable elastomeric coating. The said coating prevents the passage of smaller objects from the retrieval device (between the stem and prongs) to vicinity. Thereby, reducing chances of object slippage and increase capturing efficiency.
[0026] The retrieval device alternates between an expanded configuration and a collapsed configuration. In expanded configuration, the grasping arms are extended to capture the targeted object(s). In collapsed configuration, the grasping arms are in compressed state with/without the target object. The grasping arms may optionally be covered by a micro catheter in the collapsed state.
[0027] Despite being multipronged, the profile of the coil retrieval 100 is compatible with at least 3F micro-catheter.
[0028] Now referring specifically to diagrams, FIG. 1 represents the retrieval device 100 in expanded state. The retrieval device 100 may be deployed inside a patient’s vasculature anatomy using a micro-catheter.
[0029] The retrieval device 100 may be fabricated from a durable and a biocompatible material such as a metal. For example, the retrieval device 100 is made from nitinol. Further, retrieval device 100 may be fabricated from titanium, stainless steel, cobalt chromium, etc.
[0030] As represented, the retrieval device 100 includes at least three grasping arms 103 supported on a circumferential edge of one end of a core member 105. For example, the grasping arms 103 may be equidistantly disposed at an interval of approximately 120° on the circumferential edge of the one end of the core member 105. The grasping arms 103 may be connected with core member 105 by using techniques such as welding, coupling, adhesive bonding, etc. Alternately, the grasping arms 103 and the core member 105 may be fabricated as an integral assembly.
[0031] In an embodiment, the grasping arms 103 and the core member 105 are disposed along a longitudinal axis ‘L’ of the retrieval device 100.
[0032] As depicted, each grasping arm 103 includes a stem 103a and at least two prongs 103b. However, the higher number of prongs 103b, say three to six can be employed by the retrieval device of the instant invention.
[0033] The variable number of prongs 103b on each stem 103a may also lie in the scope of invention. Say in the retrieval device 100 one stem 103a may be attached to two prongs 103b, while the other stem 103a may be attached to three prongs 103b.
[0034] The prongs 103b and the stem 103a of the grasping arms 103 may be connected together by using techniques such as welding, coupling, adhesive bonding, etc. Alternately, prongs 103b and the stem 103a of the grasping arms 103 may be fabricated as an integral assembly.
[0035] The structure/components of each grasping arm 103 may be same or different. The following description elaborates grasping arms 103 with identical structures. In an embodiment the dimension of all the grasping arms 103 are same.
[0036] The stems 103a may be in the form of a bar or rod with predefined dimensions. For example, the width of the stems 103a may vary from 50µm to 150µm. The length of the stems 103a may vary from 3mm to 10mm. In an exemplary embodiment, the length of the stems 103a is 6mm, while the width of stem is 120µm respectively. The stems 103a of the present invention are wide enough to firmly hold the prongs 103b.
[0037] Each stem 103a includes a distal end ‘a1’ and a proximal end ‘a2’. The proximal end ‘a2’ of the stems 103a may be angled at an angle ‘a’ with respect to the circumferential edge of the core member 105 as shown in FIG. 1. The angle ‘a’ between the stems 103a and the core member 105 ranges between 90° to 130°. In an embodiment, the angle ‘a’ between the stem 103a and the core member 105 is 120°.
[0038] The prongs 103b may include a distal end ‘b1’ and a proximal end ‘b2’. The edges of the prongs 103b may be smooth to ensure minimal damage to the organs/tissues that would be in contact with the retrieval device upon deployment. The distal end ‘b1’ of each prong 103b may include an extension member ‘b3’. Each extension ‘b3’ may extend from the distal end ‘b1’ at a finite angle ranging between 80°to 100° in expanded state. In an embodiment, the extension member ‘b3’ may be perpendicular to the distal end ‘b1’ of the prong 103b (as shown in Fig.1b and Fig.2b (top view)). The length and width of the extension member ‘b3’ may range from 0.23mm to 0.37mm and 50µm and 150µm respectively. In an exemplary embodiment, the length of the extension member ‘b3’ is 0.3mm, while the width of extension member ‘b3’ is 120µm respectively.
[0039] These extension members form a cage like structure which helps in providing better coverage on the top for entrapping an object. The extension member ‘b3’ helps in easy capture and subsequent retrieval of the targeted objects.
[0040] The proximal end ‘b2’ of each prong 103b may be connected to the respective distal end ‘a1’ of the stem 103a at a predefined angle ‘ß’ with respect to the stem 103a. The angle ‘ß’ may be in the range from 135° to 170°. In an embodiment, the angle ‘ß’ is 150°.
[0041] In an embodiment, the prongs 103b on each stem have a vertical axis ‘V’ which is inclined with respect to the longitudinal axis. For example, the vertical axis ‘V’ of the prongs 103b may make an angle ranging from 10° to 30° with the longitudinal axis. The said angle prevents jumbling of prongs and helps to provide optimum radius to the device in the expanded state, increasing its capturing efficiency.
[0042] The prongs 103b may be spaced at a finite distance from each other in a V-shaped configuration as represented in FIG. 1. In an embodiment represented in FIG. 1, the prongs 103b make an angle ‘?’ of 10° with respect to each other. The angle ‘?’ between two prongs 103b of a stem 103a may range from 10° to 15°. Alternatively, the prongs 103b may be connected to each other and subsequently coupled to the stem 103a in a U shaped manner. In such case, the two prongs 103 b may make an angle ‘Y’ ranging from 35° to 45° with each other. In an embodiment where the prongs 103b are in U-shaped arrangement, the angle ‘Y’ between the two is around 41°as shown in Fig. 2.
[0043] The prongs 103b may include predefined dimensions. For example, the width of the prongs 103b may vary from 50µm to 150µm. The length of the prongs 103b may vary from 0.5mm to 2mm. In an exemplary embodiment, the length and width of the prongs 103b is 1.4mm and 120µm respectively. The stems 103a of the present invention are wide enough to firmly hold the prongs 103b. In an embodiment, all prongs 103b have same dimensions.
[0044] It must be noted that the number of the prongs 103b and/or stem 103a of the retrieval device 100 may vary in number. The variation in number entirely depends on the dimension of the targeted object(s), the dimension of the artery from where the targeted object has to be captured, the application of the retrieval device 100 and size of the targeted object.
[0045] For instance, the number of stems 103a may range from 2 to 3 for cerebral applications due to smaller diameter of a cerebral vessel. Whereas, around 3 to 6 stems 103a are favored for retrieval of objects from peripheral vasculature due to large diameter of its lumen. However, the number of prongs 103b may vary from 2 to 6 on each stem for cerebral applications and from 6 to 12 on each stem for peripheral applications. Further, more force may be required to retrieve large objects which indicates requirement of even higher number of prongs 103b and/or stems 103a to produce adequate force to grasp and hold the targeted object. Beside large diameter of a lumen, use of a catheter in peripheral applications facilitates inclusion of more number of prongs or stem.
[0046] FIG. 1a depicts the retrieval device 100 of FIG. 1 in compressed state.
[0047] Each retrieval device 100 is coupled to a micro catheter at a proximal end of the retrieval device100. In order to compress a retrieval device 100, the micro catheter is pushed/slid distally to exert pressure on the stems 103a and/prongs103b of the retrieval device 100. This results in closure/compression of the stems 103a/prongs103b. Generally, such compression is required when a targeted foreign object is to be captured by the retrieval device 100. First, the expanded retrieval device 100 is positioned such that it encompasses the targeted foreign object. Thereafter, the micro catheter is slid distally to close the stems 103a/prongs103b of the retrieval device 100 to capture the targeted foreign object. It may be noted that any micro catheter may be employed that is compatible with the retrieval device 100 of the instant invention.
[0048] In the compressed state, the stems 103a may be inclined at an angle (a’) ranging from 90° to 100° with respect to the core member 105. In an embodiment, the stems 103a are inclined at an angle (a’) of 90° to 95° with respect to the core member 105 in compressed state. In the compressed state, the prongs 103b make an angle (?’) ranging from 1° to 10° with respect to each other. In an embodiment as represented in FIG. 1a, the angle (?’) between the two prongs 103b is 1° to 5° in the compressed state. The angle (ß’) between the proximal end ‘b2’ of prongs 103b and distal end ‘a1’ of stem 103a may range from 150° to 160° in compressed state. In an embodiment, the angle (ß’) between the proximal end ‘b2’ of prongs 103b and distal end ‘a1’ of stem 103a is 155°.
[0049] FIG. 2 depicts an alternate embodiment of the retrieval device 100 in an expanded state. The prongs 103b are be connected to each other and subsequently coupled to the stem 103a say, in a U-shaped configuration. As illustrated in FIG. 2, the prongs 103b of the retrieval device 100 have smooth edges. The curvature between the prongs 103b and the stem 103a exerts more pressure on the prongs 103b, when the micro-catheter slides on the grasping arms 103. Therefore, curved prongs 103b as represented in FIG. 2 provide better grip for capturing the targeted object.
[0050] The proximal end ‘b2’ of prongs 103b may be connected to the distal end ‘a1’ of stem 103a at a predefined angle ‘B’ with respect to the stem 103a. The angle ‘B’ may be in the range from 135° to 170°. In an embodiment, the angle ‘B’ is 150°
[0051] The prongs 103b in FIG. 2 may be connected to each other in a U-shaped arrangement and subsequently, the bottom of the U-shaped arrangement of the prongs 103b is coupled to the stem 103a. The prongs 103b may be at an angle ‘Y’ of around 41° with respect to each other as shown in Fig. 2. The angle ‘Y’ between two prongs 103b may range from 35° to 45°.
[0052] Each stem 103a includes a distal end ‘a1’ and a proximal end ‘a2’. The proximal end ‘a2’ of the stems 103a may be angled at an angle ‘A’ with respect to the circumferential edge of the core member 105 as shown in FIG. 2. The angle ‘A’ between the stems 103a and the core member 105 ranges between 90° to 130° with respect to 105. In an embodiment, the angle ‘A’ between the stem 103a and the core member 105 is 120°.
[0053] It may be noted that other specific constructional features like dimensions/features of the stem, prongs, etc. may be referred from FIG. 1 and has not been repeated for brevity.
[0054] FIG. 2a depicts the retrieval device 100 of FIG. 2 in the compressed state.
[0055] In the compressed state, the stems 103a are inclined at an angle (A’) ranging from 90° to 100° with respect to the core member 105. In an embodiment, the stems 103a are inclined at an angle (A’) of 90° to 95° with respect to the core member 105 in compressed state. The prongs 103b make an angle (Y’) which ranges from 5° to 15° with respect to each other. In an embodiment represented in FIG. 2a, the angle (Y’) between two prongs 103b is 8° to 12° in compressed state. The angle between the proximal end ‘b1’ of the prong 103b and the extension member ‘b3’ remain same in compressed state. The angle (B’) between proximal end ‘b2’ of prongs 103b and distal end ‘a1’ of stem 103a may range from 150° to 160° in compressed state. In an embodiment the angle (B’) between proximal end ‘b2’ of prongs 103b and distal end ‘a1’ of stem 103a is 155°. Additionally, the retrieval device 100 as explained in FIGs. 1 & 2 may include a plurality of radiopaque markers say, two to twelve markers (not shown). The markers may be in the form of round, rectangular, oval or square shapes. The presence of radiopaque markers provides better tracking of the retrieval device 100 through enhanced radiopacity during treatment procedure. The radiopaque markers may be made of platinum, tantalum, gold, iridium or iridium-platinum, etc.
[0056] The radiopaque marker may be affixed at stems 103a or prongs 103b of retrieval device. The number of radiopaque markers is same or different at 103a and 103b. For instance, the number of radiopaque markers ranges from 3 to 9 in number. The markers may be fixed either on stems or prongs or both.
[0057] Further, the different embodiments of the grasping arms 103 as described above may be partially or wholly coated with a coating (As shown in fig. 1c and fig. 2c). The coating may be non-degradable elastomeric coating. Coating on the grasping arms 103 can be provided by any available coating methods like spray coating, dip coating, spin coating, electro-spin coating, rolling, sputtering, vapor deposition, plasma coating etc. In a preferred embodiment, electro-spin coating is used to form a cover on the grasping arms 103. The coating may include one or more coating polymers such as, without limitation, poly (dimethylsiloxane), PTFE, ePTFE, polyethylene glycols (PEG), poly(ethylene oxide) (PEO), polyurethane, poly(propylene) (PP), poly(ether-urethanes) (PU), poly(ethylene terphthalate) (PET), etc.
[0058] Such a coating helps to enhance the grip of the retrieval device 100 during capturing the targeted object and also reduces the chances of the skipping of the targeted object. The coating of non-degradable polymer prevents passing of smaller object between the stem and/or prongs. Therefore, the chances of object slippage are greatly reduced and the capturing efficiency is increased.
[0059] Alternatively, the retrieval device 100 may have a knitted mesh made up of a polymeric filament or a metal alloy wire, mounted around the device (As shown in fig. 1d and fig. 2d). Further, the porosity of the mesh may vary depending on the size of the foreign object. For example, for capturing coil, mesh with porosity of more than 200µm is suitable. Whereas, for capturing a clot and/or liquid emboli, porosity of the mesh may range from 50µm to 150µm to reduce the chances of slippage of the clot and/or emboli.
[0060] Further, knitting or coating may fully or partially cover the grasping arms by formation of a cage like structure. Knitting or coating helps in better holding or capturing of the foreign entities and reduces the chance of slippage of the foreign object.
[0061] FIG. 3 depicts an exemplary flowchart of the method of manufacturing the retrieval device 100. At step 301, the retrieval device 100 may be fabricated using, without limitation, laser cutting or braiding.
[0062] In an embodiment, the retrieval device 100 may be fabricated by braiding nitinol wires. The diameter of a nitinol wire may range from 10 µm to 100 µm, preferably range from 20 µm to 80 µm, and more preferably 40µm to 60µm. The number of the nitinol wires to make the retrieval device 100 range from 8 to 72.
[0063] Alternatively, the retrieval device 100 can be made using laser cutting. A nitinol (or any other metal) tube may be laser cut in a predefined pattern to create the retrieval device 100. In the present invention, diameter of a nitinol tube ranges from 0.2 mm to 1.2 mm and more preferably 0.3 mm to 0.95 mm.
[0064] At step 303, the retrieval device 100 may undergo grinding and/or honing process. Grinding helps in producing smooth surface and helps to hold precise tolerances of bore diameter. Subsequently, honing process may be performed using say, alconox-powder precision cleaner. Alternatively, instead of grinding & honing, descaling can be performed for removing burs and smoothening the surface of the retrieval device 100.
[0065] At step 305, the retrieval device 100 is subjected to a heat treatment process (annealing) for shape setting. The shape setting is done by constraining the retrieval device 100 on a mandrel or mold of the desired shape and applying an appropriate heat treatment process. The mold is kept in a furnace at a temperature ranging from 490°C to 520°C for 5 mins to 20 mins. As an example, the temperature may be applied for 8 to 17 mins between 500°C to 510°C. Further, the mold is removed from the furnace and allowed to cool at a room temperature. Alternately, the mold may be cooled through a quenching process. In the quenching process, the mold is removed from the furnace and immediately put into water for 10 to 20 mins as required.
[0066] At step 307, sandblasting of the retrieval device 100 may be performed post the heat treatment process. In an embodiment, the process of sandblasting is done to remove the oxide layer over the nitinol tube surface that results in highly smooth surface and also to remove pulse marks and striations left by laser cutting, slag, abrasive particles, decrease the propensity for microcracking and improve adhesion characteristics.
[0067] At step 309, the retrieval device 100 may be electropolished or passivated to yield a finished product.
[0068] The retrieval device 100 for retrieving objects is attached to a delivery system, a torque device, etc. that support the operation of the retrieval device.
[0069] 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.