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:
RETRACTION UNIT AND MECHANISM FOR DELIVERY DEVICE
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:

FILED OF THE INVENTION
[001] The present disclosure relates to a retraction unit. More particularly, the present disclosure relates to a stent retraction unit for a delivery device.
BACKGROUND OF THE INVENTION
[002] Blood vessels are complex tubular networks responsible for blood circulation throughout the body. Vessel blockage at several sites due to various causes can hinder normal blood flow rate which may lead to many complications. To prevent this blockage, a tiny mesh like tubular structure such as a stent, is deployed at the site through various openings via a delivery device often, by a medical practitioner. After deployment, the stent maintains proper amount of blood flow at the deployed site.
[003] A stent can be deployed using a stent delivery system. A delivery system typically includes a catheter, a hub and a tip amongst other components, if any. The stent is mounted on the catheter and is deployed in a native vessel. During deployment of a stent, the stent may be misaligned or misplaced due to various factors such as incorrect positioning of the tip in the native vessel, dislocation of the stent in a catheter, etc. This misalignment and misplacement can cause damage to the blood vessel. The damage can cause pain, arrhythmias, strokes, etc.
[004] Currently, the solutions to address the aforesaid drawbacks, present devices that hold edges of a stent from outside. Due to this, deployment of the stent becomes complex, requiring the device to be decoupled first and then move the catheter to deploy a stent. Therefore, there arises a need for a holding unit that can be used along with various stent delivery devices for smooth deployment of a stent.
SUMMARY OF THE INVENTION
[005] 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 mere 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.
[006] The present disclosure relates to a stent retraction unit for a delivery device. In an embodiment, retraction unit is a holding element for retracting a stent during pre-mature deployment. The holding element includes a base and plurality of prongs. The base includes a proximal and distal edge. At the distal edge of the base the plurality of prongs is established. At least a portion of prongs include a flare profile towards its distal segment to hold the stent from its inner surface during delivery.
BRIEF DESCRIPTION OF DRAWINGS
[007] The summary above and the detailed description of descriptive embodiments, is better understood when read in conjunction with the apportioned drawings. For illustration of 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.
[008] Fig. 1a depicts an isometric view of a holding element 100, according to an embodiment of the invention.
[009] Figs. 1b-1c depicts a side view of the holding element 100, according to an embodiment of the present invention.
[0010] Fig. 1d depicts an isometric view of a holding element 100 with an impression 103 according to an embodiment of the present invention.
[0011] Figs. 1e-1f depicts a side view of a holding element 100 with an impression 103 according to an embodiment of the present invention.
[0012] Fig. 2 depicts the holding element 100 coupled a delivery device 200, according to an embodiment of the present invention.
[0013] Figs. 3a-b depicts the delivery device 200 in pre-deployment stage, according to an embodiment of the present invention.
[0014] Figs. 3c depicts the delivery device 200 in post-deployment stage, according to an embodiment of the present invention.
[0015] Fig. 4a depicts the delivery device 200 in pre-deployment stage, according to an embodiment of the present invention.
[0016] Fig. 4b depicts the delivery device 200 during deployment, according to an embodiment of the present invention.
[0017] Fig. 4c depicts the delivery device 200 post deployment, according to an embodiment of the present invention.
[0018] Fig. 5a depicts an exemplary stent 300, according to one embodiment of the present invention.
[0019] Fig. 5b depicts an exemplary stent 500, according to another embodiment of the present invention.
DETAILED DESCRIPTION OF DRAWINGS
[0020] Prior to describing the disclosure 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.
[0021] 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.
[0022] 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.
[0023] 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 apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[0024] The present disclosure relates to a holding element capable of retracting a stent for example, during pre-mature deployment. In an embodiment, the holding element includes a base towards a proximal portion and multiple prongs towards its distal portion. Each prong includes a leg and an outwardly extending distal segment. The distal segment of the prong engages with an inner surface of a stent. Due to this coupling, the holding element grips the stent strongly. Additionally, this coupling facilitates easy loading of the stent and during final deployment, the holding element supports the stent inside the lumen by means of the prongs. The prongs of the holding element are designed in such a way that they hold the stent during the pre-deployment stage and release the same in the final deployment stage automatically. Further, no structural changes are required in stents nor any additional accessory(s) is needed in a stent delivery system to correct pre-mature deployment of a stent using the holding element of the present disclosure.
[0025] In an embodiment, upon application of an external pressure, the legs of the prongs are crimped or bent inwards forcing the distal segments of the prongs to come in close proximity defining a nearly circular structure. In turn, the distal segments of the prongs apply a repulsive force on the corresponding lumen such as stent walls, sheath, etc. ensuring the stent is retained in the sheath. The radius of this nearly circular structure of the crimped legs of the prongs is less than the radius of the stent in collapsed condition. Further, due to mating of the distal segments with the stent, retraction of the stent in conditions such as incorrect pre-mature deployment, is possible.
[0026] The holding element can be used with stent delivery devices for self-expandable stents. The prongs of the holding element grasp the stent to be delivered.
[0027] In an embodiment, the base of the holding element includes one or more impressions such as engravings, markings, imprints, etches, cavities, etc. on its outer surface. The impressions host an uneven or extending/protruding structure of a stent such as edges of larger cells, eyelets, marker cavities, extending loops of struts, etc. This helps in proper anchoring of the stent in the base. Further, a stent is not deployed fully until the markers are not removed from the impressions of the holding element of a stent delivery device. In this position (as in, the markers being partially or fully coupled to the impressions), the stent can be retracted. The impression restricts forward and backward migration of the stent from its mounted position.
[0028] Now referring to the figures, Fig. 1a illustrates an isometric view of a holding element 100. The holding element 100 is defined by a base 101 at the proximal edge 100a and multiple prongs 102 at the distal edge 100b. The holding element 100 is made of materials such as silicon, High-density polyethylene (HDPE), Low-density polyethylene (LDPE), Polyvinyl chloride (PVC), metal, carbon polymer, etc.
[0029] The base 101 of the holding element 100 can include any cross-sectional structure such as circular, rectangular, square, semi-circular, triangular, etc. The base 101 includes a proximal edge 101a, a distal edge 101b and a cavity 101c as depicted in Fig.1a. The cavity 101c couples the holding element 100 to a delivery device. In the depicted embodiment, the cavity 101c is tubular. In various implementations, the cavity 101c may be tapered, triangular, etc.
[0030] The distal portion 100b of the holding element 100 includes multiple prongs. The number of prongs 102 can depend upon the number of cells of a stent. In an embodiment, the holding element 100 includes four prongs 102. The prongs 102 extend from the distal edge 101b of the base 101 and define a circular structure. The prongs 102 may either be spaced apart on the distal edge 101b as depicted in Fig. 1a or joined together.
[0031] Each prong 102 includes a leg 102a and a distal segment 102b. The legs 102a may be discrete portions of prongs 102 from which the distal segment 102b extend. The legs 102a can be tubular, flat bar structure, etc. Alternately, the legs 102a may merge with the base 101 defining a solid tubular structure such that the distal segment 102b is provided at the distal end of the base 101.
[0032] In an embodiment, the distal segment 102b protrudes outwardly attaining a flared profile. The flared profile includes without limitation undulating, spiral, tapered, stepped, zigzag, etc. profiles. The distal segment 102b of a prong 102 may make an angle ranging from say 40° to 50° with respect to a longitudinal axis of the holding element 100. In an embodiment, the angle is 45°. While all the prongs depicted in Fig. 1 have same profile, it is possible that each prong has a different profile or at least two prongs have same profile.
[0033] In an embodiment, the prongs 102 exhibit compressibility. Due to this, the prongs 102 can attain one of two different states - a first natural/relaxed state (as depicted in Fig. 1b) where the prongs 102 are flared outwards, and a compressed state in which the prongs are compressed (as depicted in Fig. 1c). The prongs 102 can withstand load or an opposing force when in the compressed state due to the engagement with a stent. Once the prong 102 disengages with the stent 300,500, the prong 102 reverts to its natural state. The compressive forces withstood by a prong 102 range from 3N to 5N.
[0034] For example, upon application of an external pressure, the legs of the prongs are crimped or bent inwards forcing the distal segments of the prongs to come in close proximity defining a nearly circular structure. In turn, the distal segments of the prongs apply a repulsive force on the corresponding lumen such as stent walls, sheath, etc. ensuring the stent is retained in the sheath. The radius of this nearly circular structure of the crimped legs of the prongs is less than the radius of the stent in collapsed condition. Further, due to mating of the distal segments with the stent, retraction of the stent in conditions such as incorrect pre-mature deployment, is possible.
[0035] Figs. 1d depicts an alternate embodiment, where the base 101 of the holding element 100 includes one or more impressions 103 on its outer surface. The impressions 103 can extend along the length of the base 101. For example, the impressions 103 can either cover the length of the base 101 either fully or partially. The impressions 103 host an extending portion of a stent which is helpful in proper anchoring of the stent in the base 101. The extending structure of the stent can include eyelets, elongated cells, markers etc. Additionally, and optionally, at least a portion of the edge of an impression 103 may include one or more structures resembling distal segment 102b to hold a stent and to retract the same in case of improper deployment. Improper deployment includes without limitation partial deployment of a stent at an incorrect location or angle, etc.
[0036] Similar to Figs 1b-1c, Figs. 1e-1f depict the holding element 100 with impressions 103 in the first natural/relaxed state and compressed state respectively. In the compressed state, the legs 102a of the prongs 102 bend towards its axis as depicted in Fig. 1f.
[0037] The holding element 100 may be coupled to a suitable delivery system including one or more shafts. In an exemplary embodiment of Fig. 2, the delivery device 200 includes a hub 201, an outer shaft 202, an inner shaft 203, a tip 204 etc. Further, the delivery device 200 includes a proximal end 200a, a distal end 200b and a length extending therebetween. The holding element 100 can be restrained via an outer sheath 302. Further, the holding element 100 can be coupled to an inner shaft 203 of a delivery device 200. In an embodiment, the holding element 100 is coupled to the inner shaft 203 towards the distal end 200b. The outer shaft 202 and the inner shaft 203 are placed concentrically and the outer shaft 202 extends at least over a portion of the length of the inner shaft 203..
[0038] The holding element 100 can be fixed on to the inner shaft 203 or have an adjustable coupling along the length of the inner shaft 203. In an embodiment, the cavity 101c of the holding element 100 is fixedly coupled to the inner shaft 203 of the delivery device 200 as depicted in Fig. 2.
[0039] The holding element 100 is coupled to the inner shaft 203 at a predefined distance from the tip 204. The predefined distance corresponds to at least the length of the stent to be mounted on the inner shaft 203 without any hinderance. In an embodiment, the holding element 100 is positioned on the inner shaft 203 such that the distance between the tip 204 and the holding element 100 in equal to the axial length of the stent.
[0040] Fig. 3a depicts an assembly of a stent 300 enclosed in the outer sheath 302, and a delivery device 200 with a holding element 100. The stent 300 or 500 (depicted in Fig. 5a & 5b) includes mostly a tubular mesh like structure having a proximal end 300a, 500a and a distal end 300b, 500b. The mesh structure of the stent is an arrangement of struts that define peaks, valleys, extensions etc. Further, the struts may define one or more rows of circumferential cells. Further details of stent are omitted to maintain clarity. To a person skilled in the art, it will be apparent that the teachings of the present disclosure extend to self-expandable stents having one or more rows of cells.
[0041] In the depicted embodiment, the stent is mounted on the inner shaft 203 of the delivery device. The peaks defined by the struts at the proximal end of the stent 300 engage with the prongs 102 of the holding element 100 when loaded over the delivery device 200 as depicted in Figs. 3a & 4a. In an embodiment, the distal segments 102b of the prongs 102 engage with the peaks defined by the struts at the proximal end of the stent 300 and protrude from the space enclosed between the struts of the stent 300.
[0042] For deployment, the stent 300 is crimped and loaded over at least a portion of the prongs 102 of the holding element 100 which is coupled to the inner shaft 203. For example, the proximal end 300a of the stent 300 is loaded over the distal segments 102b of the prongs. Thereafter, the outer sheath 302 is mounted on the aforesaid assembly (Fig 3a). Due to this, the prongs 102 are compressed inside by the outer sheath 302 and/or the struts of the stent 300.
[0043] Once the outer sheath 302 is removed, the stent 300 expands. During deployment of the stent, the outer sheath 302 is removed slowly which exposes the distal end 300b of the stent 300 first. Once exposed, the distal end 300b of the stent 300 expands. (Fig. 3b) The unexposed portion of the stent 300 including the proximal end 300a of the stent 300 remains engaged with the holding element 100 (specifically prongs) and covered by the outer sheath 302.
[0044] While deployment, if the stent 300 is misaligned or misplaced, the holding element 100 can easily retract the stent in the outer sheath 302 on application of a pulling force by the operator. The retraction is possible due to the engagement of the proximal end of the stent 300 with the distal segment 102b of the prong 102. Due to the application of an opposing force of the prongs 102 on the proximal end 300a of the stent 300, the unexposed portion of the stent remains in the outer sheath 302 and the exposed portion of the stent 300 is pulled back inside the outer sheath 302, leading to fixing errors during pre-deployment stage.
[0045] Once the proximal end 300a of the stent 300 is exposed from the outer sheath 302 of the delivery device 200, the proximal end 300a of the stent 300 expands. The prongs 102 and the stent 300 thus disengage, due to which there is no opposing force in action. The prongs 102 attain their natural state as depicted in Figs. 3c. The stent 300 is not retractable in this position.
[0046] In an alternate embodiment, the stent 500 is crimped and loaded over the prongs 102 of the holding element 100 coupled to the inner shaft 203. The stent 500 includes one or more extending cells. These extending portions can be either larger cell, eyelets, marker cavities, extending loops on the edges of the stent 500. In an embodiment, the extending portion are eyelets 501 as shown in Fig. 5b.
[0047] 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
A holding element (100) for retracting a stent (300, 500) during pre-mature deployment comprising:
a base (101) having a distal edge (101b) and a proximal edge (101a), and
a plurality of prongs (102) that extend from the distal edge (100b), each prong includes a distal segment (102b);
wherein the distal segment (102b) of the at least one prong (102) includes a flared profile; and
wherein distal segments (102b) of the prongs (102) are configured to mate at least a portion of a proximal end (300a, 500a) of a stent (300, 500) when inserted from the inner surface of the stent (300,500), the stent (300,500) being in a collapsed state.
The holding element (100) as claimed in claim 1, wherein the distal segments (102b) of the prongs define a nearly circular structure having a radius less than a radius of the collapsed stent (300, 500).
The holding element (100) as claimed in claim 1, wherein the distal segments (102b) of the prongs (102) are one of directly or via corresponding legs (102a), coupled to the base (101).
The holding element (100) as claimed in claim 1, wherein the base (101) includes at least one impression (103) on its outer surface.
The holding element (100) as claimed in claim 1, wherein the base (101) is coupled to an inner shaft (203) of a delivery device (200) towards a distal end (200b) of the delivery device (200).
The holding element (100) as claimed in claim 1, wherein the distal segment (102b) of the prong (102) is configured to bend.
The holding element (100) as claimed in claim 6, wherein the bend of the distal segment (102b) ranges from 40° to 50°.
The holding element (100) as claimed in claim 1, wherein the holding element (100) is made of one of silicon, Low-density polyethylene (LDPE), High-density polyethylene (HDPE), Polyvinyl chloride (PVC), metal, and carbon polymer.
The holding element (100) as claimed in claim 1, wherein the base (101) includes a cavity (101c).
The holding element (100) as claimed in claim 1, wherein the stent (300,500) includes a self-expandable stent.