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:
IMPLANTABLE FILTER
2. APPLICANT:
Meril Corporation (I) Private Limited, an Indian company of the address Survey No. 135/139, Muktanand Marg, Bilakhia House, Pardi, Vapi, Valsad-396191 Gujarat, 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 an implantable filter. More specifically, the present disclosure relates to an implantable blood clot filter.
BACKGROUND OF INVENTION
[002] Pulmonary embolism is a medical condition where one or more arteries of the lungs are blocked by a blood clot. The blood clot in the arteries can disrupt blood flow, lead to insufficient oxygenation of the blood, and consequently reduce the amount of oxygen delivered to the body tissues. The blood clot that causes pulmonary embolism is generated in the deep veins of the legs. The blood clot then travels through the bloodstream, through the inferior vena cava, the heart and may lodge in an artery of the lungs.
[003] A patient suffering from pulmonary embolism may face symptoms such as shortness of breath, which may occur suddenly or gradually, sharp or stabbing chest pain that worsens with deep breathing or coughing, rapid breathing (tachypnea), and/or palpitations. Pulmonary embolisms can be life-threatening. In several cases, pulmonary embolism may lead to severe complications, such as long-term lung damage (pulmonary hypertension) and death.
[004] A patient suffering from pulmonary embolism can be treated by taking anti-coagulant medicines, or thrombolytic therapy in which the blood clot is dissolved using medication. Surgical treatment for pulmonary embolism may include pulmonary embolectomy, in which the blood clots are removed from the arteries of the lungs through a surgical procedure. Percutaneous thrombectomy, in which a catheter is inserted through a vein to reach and remove the clot. Another treatment method involves the use of a vena cava filter that is inserted into the inferior vena cava to trap blood clots before they reach the lungs.
[005] Vascular filters known in the art are often permanent filters that are implanted in the inferior vena cava of the patient for a lifetime but in many cases, the blood clot accumulation on the filter may hinder the blood flow through the inferior vena cava. Further, existing designs are prone to migration from the implantation site and/or tilting from its intended position thus hindering the blood flow, and/or reducing efficacy of capturing blood clots.
[006] Hence, there is a need for a filter that overcomes the problems associated with the filters known in art.
SUMMARY OF INVENTION
[007] 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.
[008] The present disclosure relates to an implantable filter. The filter includes a hub and a plurality of filter arms. The filter arms extend from the hub. The filter arms are arranged radially around the hub. The filter arms have a curved configuration having a curvature due to which the radial arrangement of the filter arms define a dome shape or a bell shape of the filter. Each of the plurality of filter arms include two or more apertures and one or more anchoring tips disposed at a distal end of the filter arm.
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 apportioned 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 instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[0010] Fig. 1 depicts an implantable filter (or filter) 100, implanted in inferior vena cava 10, in accordance with an embodiment of the present disclosure.
[0011] Fig. 2 depicts an isometric view of the filter 100, in accordance with an embodiment of the present disclosure.
[0012] Fig. 3 depicts an isometric view of an exemplary filter 100 with a plurality of struts 170, in accordance with an embodiment of the present disclosure.
[0013] Fig. 4 depicts an isometric view of an exemplary filter 100, in accordance with an embodiment of the present disclosure.
[0014] Fig. 5 depicts a bottom view of the filter 100, in accordance with an embodiment of the present disclosure.
[0015] Fig. 6 depicts the filter 100 attached to a delivery shaft 30 and constricted within a catheter 20, being advanced in the inferior vena cava 10, in accordance with an embodiment of the present disclosure.
[0016] Fig. 7 depicts an expanded state of the filter 100, in accordance with an embodiment of the present disclosure.
[0017] Fig. 8 depicts the filter 100 being detached from the delivery shaft 30 and implanted in the inferior vena cava (or IVC) 10, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[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, communicate 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] 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.
[0020] 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.
[0021] Furthermore, the described includes, 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 includes or advantages of a particular embodiment. In other instances, additional includes and advantages may be recognized in certain embodiments that may not be present in all embodiments. These includes and advantages of the embodiments will become more fully apparent from the following description and apportioned claims or may be learned by the practice of embodiments as set forth hereinafter.
[0022] In accordance with the present disclosure, an implantable filter, (interchangeably referred to as ‘filter’ hereinafter), is disclosed. The filter is implanted within the inferior vena cava for the treatment of pulmonary embolism. The filter of the present disclosure is implanted in the inferior vena cava of the patient to filter the blood that is flowing from the lower parts of the body and restrict the blood clots from entering the lungs that can cause pulmonary embolism. The design of the filter of the present disclosure is such that in the deployed position, the filter remains in position, that is, it does not tilt from its deployed position. The deployed position refers to the position of the filter once the filter is incorporated inside the inferior vena cava. Further, the filter catches and breaks down the blood clots.
[0023] The filter includes a plurality of filter arms that are coupled to a hub. The arms are disposed circumferentially on the hub to form at least a partially spheroid structure. The spheroid shape of the filter helps in minimizing the turbulence in the blood flow as the spheroid shape causes minimal obstruction to the blood flow. Each arm is provided with a plurality of apertures. One of the apertures is disposed towards the proximal end of the arm and the other aperture is disposed at the distal end of the arm. The plurality of apertures offer improved filtration of the blood, thereby reducing the chances of blood clot passage or leakage through the filter. The apertures allow the blood to flow through but restrict the passage of blood clots . The aperture that is disposed towards the distal end, is provided with at least an anchoring tip. The anchoring tip of is positioned at the end of the arm. The anchoring tip is pointed towards the distal end. The anchoring tip grips the tissue of the inferior vena cava.
[0024] The anchoring tips of the filter provide a firm grip on the implantation site thus, reducing the chances of migration of the filter from its implantation site. The filter arms exert a resilient force that is distributed circumferentially on the walls of the inferior vena cava thus, keeping the filter in an axial position and minimizing the chances of the filter tilting from the intended position. The filter is provided with a retriever at the proximal end. The retriever can be employed to retrieve the filter in case there is a need to replace or remove the filter from the implantation site. A minimally invasive procedure can be used for the implantation and retrieval of the filter.
[0025] Now referring to the figures, in accordance with Fig. 1 an implantable filter (or filter) 100 is illustrated, implanted within an inferior vena cava 10 of a patient.
[0026] Fig. 2 depicts the filter 100, according to one embodiment. The filter 100 may include a proximal end 100a and a distal end 100b. The filter includes a retriever 110, a hub 130, and a plurality of filter arms 150.
[0027] The retriever 110 is disposed at the proximal end 100a of the filter 100. The retriever 110 includes a bar 110a and a shaft 110b. The bar 110a and the shaft 110b together define a ‘T’ shape structure of the retriever. In an embodiment, the bar 110a has an arched shape. The bar 110a may be fixedly coupled to the shaft 110b using a coupling method including, but not limited to snap fit, welding, laser welding, soldering, brazing, and the like. In an embodiment, the bar 110a is coupled with the shaft 110b using laser welding. In an alternate embodiment, the bar 110a and the shaft 110b are a single component forming the retriever 110 of the filter 100. The retriever 110 is further coupled to the hub 130. The retriever 110 may be made up of a bio-compatible material including, but not limited to nitinol, stainless steel, cobalt chromium, titanium, and so forth. In an embodiment, the retriever is made of stainless steel.
[0028] The retriever 110 is configured to provide a gripping structure to facilitate extraction of the filter 100. The retriever 110 may attach to a suitable retrieving system. The retrieval system may be a transcatheter system which may include a catheter, a guide wire and a retrieving shaft (not shown). The catheter may be guided using the guide wire to the filter 100 though an intravenous path. The guide wire may be withdrawn once the catheter reaches in the vicinity of the filter 100. The retrieving shaft may be advanced through the catheter to the filter 100. The shaft may be provided with a plurality of wires. The wire may be made up of a material including but not limited to nitinol, stainless steel, titanium, chromium cobalt, and a combination there of. In an embodiment, the wires are made of nitinol. The wires may be folded to form loops. The retriever 110 attaches to the retrieving shaft using the wire loops. The retrieving shaft may then be withdrawn for retrieval of the filter 100. The catheter may finally be removed to conclude the retrieval of the filter 100.
[0029] The hub 130 is disposed towards the proximal end 100a of the filter 100. The hub 130 is coupled to the shaft 110b of the retriever 110. The hub 130 and the shaft 110b may be provided with internal threads and external threads respectively. The shaft 110b and the hub 130 may be coupled using the threads. In another embodiment, any other coupling method may also be used including, but not limited to, snap fit, laser welding, soldering, brazing, and so forth. In yet another embodiment, the hub 130 and the shaft 110b may be integrally formed as a single component. The hub 130 may have a suitable shape including, but not limited to circular, square, oval, and the like. In an embodiment, the hub 130 has a cylindrical shape with a hollow body and a tapered edge, towards the proximal end 100a. The diameter of the hub 130 may correspond to the shaft 110b. The diameter of the hub 130 may range between 2mm and 4mm. In an embodiment, the diameter of the hub 130 is 2.4mm. The hub 130 may be made of a biocompatible material including but not limited to stainless steel, nitinol, cobalt chromium, titanium, and so forth. In an embodiment, the hub 130 is made of stainless steel. Towards the end, the hub 130 is coupled to a plurality of filter arms (or arms) 150.
[0030] The arms 150 are arranged uniformly radially around the hub 130. Each arm 150 extends from the hub 130 to the distal end 100b of the filter 100. The arm 150 has a proximal end 150a and a distal end 150b. The proximal end 150a of the arm 150 is fixedly coupled to the hub 130 using a coupling method including, but not limited to laser welding, welding, brazing, soldering, and the like. The filter arms 150 may have a pre-defined length. The length of the filter arms 150 ranges from 40mm to 60mm. In an embodiment, the length of the filter arm is 54mm. In an embodiment, length of each filter arm 150 is kept identical. The identical length of the filter arms 150 provides a symmetrical structure to the filter 100. Such structure of the filter 100 may help in easy deployment and may increase stability of the filter 100 after the deployment of the filter 100 on the implantation site. The symmetrical structure of the filter 100 may also help in uniform distribution of radial force exerted by the filter arms 150, in circumferential direction thereby, increasing the radial strength of the filter 100.
[0031] In another embodiment (shown in Fig. 3), between two consecutive filter arms 150, a strut 170 is provided, towards the distal end 100b. The struts 170 may have a predefined shape. The shape of the strut 170 may include without limitation, a ‘V’ shape, an ‘S’ shape, a zig-zag shape, a wavy shape, a ‘C’ shape, a ‘U’ shape, and so forth. In an embodiment, the shape of the struts 170 is ‘V’ shape. The strut 170 may be integrally formed with the filter arms 150. Alternatively, the struts 170 may be an individual structure being fixedly coupled between two filter arms 150. The coupling method may include without limitation, laser welding, welding, brazing, soldering, and the like. In an embodiment the struts 170 are integrally formed with the filter arms 150. The struts 170 increase the radial strength of the filter 100. The struts 170 also facilitate uniform distribution of the stress among all the filter arms 150 thereby improving the overall strength of the filter 100.
[0032] The filter arms 150 may be fabricated by a process including, but not limited to laser cutting and the like. In an embodiment, the arm 150 is fabricated by laser cutting. The arm 150 may be made of a suitable material having pre-defined properties including but not limited to nitinol, cobalt chromium, titanium, stainless steel, and the like. The properties of the material may include shape memory, strength, super-elasticity, radiopacity, and so forth. Each filter arm 150 is fabricated as a single structure which makes the filter arms 150 jointless. The jointless structure of the filter arm 150 eliminates any chances of stress concentration at any point on the arms 150 thereby, increasing the overall strength of the filter 100.
[0033] Each filter arm 150 has a curved configuration, comprising a curvature with respect to a central axis of the filter 100. The filter arms 150 have a curve from the proximal end 150a to the distal end 150b. The curvature of the plurality of filter arms 150 defines one of a hemispheroid structure of the filter 100, a dome shape of the filter 100, or a bell shape of the filter 100.
[0034] Each filter arm 150 is provided with one or more apertures, for example, a first aperture 151 and a second aperture 153. In another embodiment, the filter arms 150 may have more than two apertures. In an embodiment, the filter arm 150 is integrally formed, thus defining jointless first apertures 151 and second apertures 153 in the filter arm 150. The apertures (aperture 151 and 153) are configured to function as vents, to allow substantially unrestricted blood flow through them. Such an arrangement ensures a clinically acceptably small or substantially no drop in blood pressure across the filter 100.
[0035] The first aperture 151 is located at a point on the filter arm 150 between the hub 130 and the distal end 150b of the filter arm 150. In another embodiment, the first aperture is placed at a position different from the position shown in Fig. 2. The first aperture 151 may be an integral component of the arm 150. The first aperture 151 may have a pre-defined shape including, but not limited to oval, elliptical, square, rectangle, circle, diamond, pentagon, hexagon, and the like. In an embodiment, the first aperture 151 has an oval shape. The first aperture 151 may be configured to allow the blood to flow through but trap the blood clots to prohibit them from entering the lungs via the heart.
[0036] The second aperture 153 is disposed at the distal end of the filter arm 150. The second aperture 153 may also be an integral part of the arm 150. In an embodiment, the shape and size of the first aperture 151 is identical to the shape and size of the second aperture 153. In another embodiment, the shape and size of the first aperture 151 is distinct from the second aperture 153. The presence of multiple apertures on the filter arms 150, allows the filter 100 to filter the blood properly and restrict any of the blood clots by breaking them within a short period of time, that reduces the chances pulmonary embolism. It should be appreciated that the number of apertures, the shape of individual apertures, and the position of the apertures may vary without departing from the scope of the disclosure. Various combinations of the shape, the number, and the position of apertures is envisioned, without departing from the scope of the disclosure. Some embodiments may include a different number, a different shape, or a different position of the aperture on the different filter arms 150.
[0037] In an exemplary embodiment (shown in Fig. 4), the distal end 150b of the filter arm 150 is split into at least two branches. The branches may form a U-shape, a V-shape, etc. Each branch terminates with at least one second aperture 153. The distal end 150b of the filter arm 150 thus includes at least a pair of second apertures 153. In case more than one second aperture 153 is present in each branch, the second apertures 153 may be placed longitudinally. The pair of second apertures 153 are positioned radially defining the circumference of the filter 100. The increased number of apertures provides improved filtration.
[0038] It may be noted that the shape, the number, and the position of apertures may be dictated by fluid dynamics of the blood flow and may be defined at the time of designing the filter 100. Alternatively, or additionally, the shape, the number, and the position of apertures may be dictated by patient specific parameters, such as density of blood, the specific gravity of blood, the viscosity of the blood, the nominal blood pressure range of the patient, the serum composition of the patient (for example, platelet count), and so forth. Such parameters may also be factored in the design stage of the filter 100, particularly in embodiments where patient specific customized filters are fabricated, or selected from a range of available filters 100.
[0039] The second aperture may make direct contact with the walls of the inferior vena cava 10. The second aperture 153 may hold the filter 100 in position adjacent to the wall of the inferior vena cava 10 by means of friction. In some embodiments, to enhance the hold of the filter 100 on the walls of the inferior vena cava 10, the distal end of the second aperture 153 may be pointed to form an anchoring tip 153a at least partially extending radially outwards. The anchoring tips 153a are disposed at the distal end of the filter arms 150. The anchoring tip 153a may have a pointed end configured to be anchored in the internal walls of the inferior vena cava 10. The anchoring tip 153a may provide a firm hold in the inferior vena cava 10, allowing the filter 100 to withstand the flow of blood inside the inferior vena cava 10. The anchoring tip 153a may also prevent migration of the filter 100, and/or prevent tilting of the filter 100, under the force of blood flowing through the inferior vena cava 10.
[0040] In accordance with Fig. 3, each of the arm 150 is positioned radially at an equal distance from each other on the hub 130. The distal ends 150b of the filter arms 150 may define a diameter of the filter 100. The diameter of the filter 100 may correspond to the diameter of the inferior vena cava 10. The diameter of the filter 100 may range from 20mm to 40mm. In an embodiment, the diameter of the filter 100 is 30mm. The filter arms 150 may be configured to exert a radial resilient force toward the walls of the inferior vena cava 10, thus maintaining the filter 100 in a linear orientation that aligns with the axis of the inferior vena cava 10. The filter arms 150 may have resilient a property that may make the filter arms 150 self-expandable. Such a self-expandable design ensures a firm grip of the filter 100 to the interior walls of the inferior vena cava 10, substantially inhibiting or completely preventing the migration of the filter 100, and/or the tilting of the filter 100, under the force of blood flowing through the inferior vena cava 10.
[0041] During a medical procedure, the filter 100 of the present disclosure may be implanted at the target site using a minimally invasive technique, such as trans-catheterization. Figs. 6, 7, and 8 illustrate the various steps of implanting the filter 100, according to one embodiment. The trans-catheterization or transcatheter delivery of the filter 100 is carried out by using a delivery catheter 20, and a delivery shaft 30. Fig. 6 illustrates a first step, of manoeuvring the filter 100 to a location of implant. The filter 100 is pre-loaded in a delivery catheter 20. The filter 100 remains in the constricted position inside the delivery catheter 20. In an exemplary embodiment, a distal end of a delivery shaft 30 is coupled to the proximal end 100a of the filter 100 at the hub 130. In an exemplary embodiment, the hub 130 has a hole (not shown). The hole may include one or more threads. The one or more threads of the hole are configured to mate with the corresponding one or more threads on the head of the delivery shaft 30 as shown in Fig. 4. The screw-type mechanism ensures easy attachment/detachment of the filter 100 from the delivery shaft 30 and prevents shear failure or slipping of the filter 100 with respect to the delivery shaft 30 during loading and deployment of the filter 100. In various other embodiments, the delivery shaft 30 may be engaged with the hub 130 using other mechanisms such as a gripper mechanism.
[0042] In the first step, a guide wire (not shown) is introduced into the patient’s body via an appropriate vascular access point, e.g., through the transfemoral groin of a patient. The guide wire is advanced to the implantation site (i.e., IVC) till it reaches the desired implantation site. Thereafter, a catheter 20 is inserted over the guidewire. Once the catheter 20 reaches within the vicinity of the implantation site, the guide wire is withdrawn. The delivery shaft 30 with the filter 100 is then navigated to the implantation site via the catheter 20. Fluoroscopic imaging techniques may be used to guide and monitor the advancement of the catheter 20 during the procedure.
[0043] Fig. 7 illustrates the stage when the catheter 20 is positioned at the implant target site. Once the delivery shaft 30 reaches the implant target site, the catheter is withdrawn. The withdrawal of the catheter 20 causes the filter 100 to emerge out, and radially self-expand, thus causing the anchoring tips 153a to engage with the walls of the inferior vena cava (IVC) 10. The filter 100 is now fixed in position at the implant target site.
[0044] Fig. 8 illustrates the final stage of implanting, where the implanting tools are withdrawn. The filter 100 is detached from the delivery shaft 30. by unscrewing the distal end of the delivery shaft 30. Once the filter 100 is positioned in the IVC, the catheter 20 and delivery shaft 30 are withdrawn from the inferior vena cava (IVC) 10 and extracted from the vascular access point of entry.
[0045] 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. , Claims:WE CLAIM:
1. An implantable filter (100) comprising:
a hub (130); and
a plurality of filter arms (150) extending from the hub (130) and arranged radially around the hub (130), each of the plurality of filter arms (150) being of a curved configuration;
wherein the each of the plurality of filter arms (150) comprise:
two or more apertures (151, 153), and
one or more anchoring tips (153a) disposed at a distal end of the filter arm (150).
2. The implantable filter (100) as claimed in claim 1, wherein the curved configuration of the filter arms (150) includes a curvature with respect to a central axis of the filter (100).
3. The implantable filter (100) as claimed in claim 2, wherein the curvature of the filter arms (150) defines one of a hemispheroid shape of the filter (100), a dome shape of the filter (100), or a bell shape of the filter (100).
4. The implantable filter (100) as claimed in claim 1, wherein the one or more apertures (151, 153) comprise one of an oval shape, an elliptical shape, square, rectangle, diamond, pentagon, hexagon, and a circular shape.
5. The implantable filter (100) as claimed in claim 1, wherein the each of the plurality of filter arms (150) includes:
a first aperture (151) located at a point on the filter arm (150) between the hub (130) and a distal end of the filter arm (150); and
a second aperture (153) located at the distal end of the filter arm (150).
6. The implantable filter (100) of claim 5, wherein a size and a shape of the first aperture (151) is distinct from a size and a shape of the second aperture (153).
7. The implantable filter (100) as claimed in claim 5, wherein a size and a shape of the first aperture (151) is identical to a size and a shape of the second aperture (153).
8. The implantable filter (100) as claimed in claim 1, wherein the one or more anchoring tips (153a) extend radially outward from a distal end of the filter arm (150).
9. The implantable filter (100) as claimed in claim 1, further comprising a retriever (110) coupled to the hub (130), the retriever (110) configured to provide a gripping structure to facilitate extraction of the implantable filter (100).
10. The implantable filter (100) as claimed in claim 1, wherein between two consecutive filter arms 150, a strut 170 is provided, towards the distal end 100b.
11. The implantable filter (100) as claimed in claim 11, wherein the strut 170 includes a ‘V’ shape, an ‘S’ shape, a zig-zag shape, a wavy shape, a ‘C’ shape, or a ‘U’ shape.
12. The implantable filter (100) as claimed in claim 1, wherein the distal end 150b of the filter arm 150 is split into at least two branches.
13. The implantable filter (100) as claimed in claim 13, wherein the branches include a U-shape or a V-shape.
14. The implantable filter (100) as claimed in claim 1, wherein each branch includes the at least one second aperture 153 at the distal end.