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

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

 
FIELD OF INVENTION
[1] The present invention relates to a medical implant. The invention particularly relates to a stent.
BACKGROUND OF THE INVENTION
[2] The aorta is a cane-shaped artery and is the largest blood vessel in the body. The aorta is responsible for transporting nutrient-rich blood to the systemic circulation following ejection from the left ventricle of the heart. In other words, the aorta delivers oxygenated blood from the heart to the rest of the body.
[3] The aorta extends from the left ventricle of the heart to the proximal iliac bifurcation in the abdomen. The aorta may be divided into various segments depending on route/path and location including, the aortic root (not shown), the aortic valve, the thoracic aorta and the abdominal aorta, as shown in Fig. 1a. The aortic root is the section of the aorta that is attached to the heart. The aortic root is the widest part of the aorta. The entire structure at the base of the aorta where the aortic valve is located is referred as the aortic root.
[4] The aortic valve includes three flaps of tissues (leaflets) that snap open and shut to release oxygen-rich blood from the heart. The thoracic aorta consists of the ascending aorta, the aortic arch, and the descending aorta. The ascending aorta is the upward curve of the aorta after the aorta leaves the heart. The aortic arch is the curved segment that bridges the ascending aorta and the descending aorta. The curved segment of the aortic arch gives the aorta its cane-like shape. The descending aorta passes through the diaphragm’s aortic hiatus and continues as the abdominal aorta. The abdominal aorta terminates as it bifurcates into common iliac arteries, which subsequently provide arterial supply to the pelvis and lower limbs.
[5] An aortic aneurysm refers to a localized and abnormal dilation or bulging in the wall of the aorta. This condition occurs due to a weakening or thinning of the aortic wall. Over time, the wall of the aorta may become less resilient or weaken, and under the force of blood flow, it may start to expand or bulge, resulting in an aneurysm. If left untreated, this bulging can cause significant risks, such as rupture or dissection, which may be life-threatening.
[6] Aortic aneurysms can occur in different parts of the aorta. The most common types are thoracic aortic aneurysms (TAA) and abdominal aortic aneurysms (AAA), as shown in Fig. 1b.
[7] A thoracic aortic aneurysm (TAA) occurs in the part of the aorta that runs through the chest. It forms when the aortic wall weakens, leading to a bulge. This can cause complications like chest pain, hoarseness, or difficulty in swallowing, as the aneurysm may affect nearby structures.
[8] An abdominal aortic aneurysm (AAA) occurs in the section of the aorta that passes through the abdomen. AAAs are more common than TAAs and are often linked to conditions like atherosclerosis, high blood pressure, or smoking. Symptoms may include lower back or abdominal pain. If an AAA ruptures, it is a medical emergency, often causing severe internal bleeding.
[9] In some cases, an aortic aneurysm can affect both the thoracic and abdominal aorta, creating a thoracoabdominal aortic aneurysm (TAAA). This occurs when the aneurysm extends through both the descending aorta and the abdominal aorta. In these cases, the aneurysm may affect the major branches of the aorta that supply blood to critical organs such as the kidneys, intestines, and spinal cord.
[10] To maintain patency/ structure of blood vessels, stenting in the blood vessel is performed. This process is known as endovascular aneurysm repair (EVAR). Stenting is a minimally invasive procedure where a stent (a fabric tube supported by metal mesh) is delivered to the aneurysm site and deployed to seal the aneurysm, redirecting the blood flow through the stent, as shown in Fig. 1c. The stent reinforces the weakened portion of the aorta, and keeps a vessel lumen intact to facilitate normal blood flow.
[11] However, endoleaks may occur after an EVAR procedure when blood continues to flow into the aneurysm sac. This happens due to several reasons such as, for example, in case of type I endoleaks, one of a proximal end or a distal end of the stent, fails to create a tight seal with the aortic wall (as shown in Fig. 1d). A poor seal at the top or bottom edge of the stent allows blood to enter the aneurysm sac directly from the aorta. Over time, the stent may shift or migrate, particularly if it is not securely fixed at the ends, resulting in seal failure and the development of endoleaks.
[12] Alternately, type III endoleaks may happen due to disconnection between modular components of a multipiece graft, potentially leading to direct pressurization of the aneurysm (as shown in Fig. 1e). These leaks can prevent complete isolation of the aneurysm, allowing blood flow into the sac, which may lead to expansion, rupture, or other complications.
[13] To overcome the problem of endoleaks, an extension stent is used to extend the coverage of the primary stent and to ensure the repair of the aneurysm. The extension stent extends the primary stent (as discussed above) into healthier sections of the aorta or iliac arteries to ensure a secure seal.
[14] Conventional extension stent may fail to fully seal the vessel wall. These issues primarily arise from limitations in design, deployment, or the interaction of extension stent with complex vascular anatomies or with the primary stent. Poor sealing of the edge of the extension stent with the aortic vessel and/or the lumen of the primary stent may lead to increased endoleaks risk.
[15] Therefore, there is a need for an extension stent which overcomes the drawbacks of the existing ones.
SUMMARY OF THE INVENTION
[16] The present invention relates to a stent. The stent has a proximal section and a distal section. A middle section is sandwiched between the proximal section and the distal section. In an embodiment, the stent includes a plurality of rows of struts, a plurality of first linkages, a plurality of second linkages and a plurality of third linkages. The plurality of rows of struts extends circumferentially to form a plurality of closed units and a plurality of open units. The plurality of closed units is provided towards the proximal section and the distal section. The plurality of open units is provided in the middle section. The plurality of first linkages is configured to interlink two adjacent rows of struts of the proximal section and distal section to form the plurality of closed units. The plurality of second linkages is configured to interlink one peak and one trough of two adjacent rows of struts. The plurality of third linkages configured to interlink one trough and one peak of two adjacent row of struts. Wherein, two adjacent rows of struts provided in the middle section of the stent are interlinked by one of the second linkage or the third linkage to form the plurality of open units.
[17] Further, a method of fabricating the stent is disclosed. The method involves a step of providing a tubing of a biocompatible material and machining the tubing as per a digital design of the stent. Thereafter, the method includes heat-setting the machined tube for setting shape of the stent in an expanded state. In an embodiment, the machined tube is subjected to a first predefined temperature for a first predefined time period, during the heat-setting step. Thereafter, the method includes a step of finalizing the stent using at least one of a grinding, a sand-blasting or an electro-polishing process.
[18] The foregoing features and other features as well as the advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[19] 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 instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[20] Figs. 1a-1e depict an anatomical diagram of the aorta extending between the heart and abdomen.
[21] Fig. 2a depicts a stent 200 in a collapsed state, according to an embodiment of the present disclosure.
[22] Fig. 2b depicts the stent 200 in an expanded state, according to an embodiment of the present disclosure.
[23] Figs. 2c-2e depict flat views of the stent 200, according to an embodiment of the present disclosure.
[24] Fig. 2f depict the stent 200 having a flared portion 200f, according to one embodiment of the present disclosure.
[25] Fig. 3 illustrates a method 300 of fabricating the stent 200, according to an embodiment of the present disclosure.
[26] Fig. 4a depicts the stent 200 provided on a first mandrel 400, according to an embodiment of the present disclosure.
[27] Fig. 4b depicts the stent 200 provided on a second mandrel 450, according to an embodiment of the present disclosure.
[28] Fig. 5 illustrates a flowchart of a method 500 of deploying the stent 200 at a target site, according to an embodiment of the present disclosure.
[29] Fig. 6 depicts a delivery system 600 for delivering the stent 200 at the target site, according to an embodiment of the present disclosure.
[30] Figs. 7a-7b depicts delivery of the stent 200 at the target site using the delivery system 600, according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[31] 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.
[32] 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.
[33] 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.
[34] 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.
[35] A primary stent graft refers to the main endovascular stent graft initially deployed to treat one or more of AAA, TAA or TAAA. The primary stent graft bypasses an aneurysm sac and restores vessel integrity, as shown in Fig. 1c.
[36] An extension stent graft refers to an additional endovascular stent graft used to extend the primary stent graft by increasing its length, enhancing the coverage or sealing of the primary stent graft in the treatment of AAA/TAA/TAAA. The extension stent graft is deployed when the primary stent graft fails to provide adequate seal or coverage, often due to improper positioning or endoleaks.
[37] The present invention relates to an extension stent (hereinafter, stent). The stent prevents endoleaks, thereby eliminating aneurysm rupture. The stent may be balloon-expandable or self-expandable. In an embodiment, the stent is self-expandable. Although, the stent of the present disclosure is exemplified for use in type III endoleaks that occur in abdominal aortic aneurysm, the teachings of the present disclosure are equally applicable to type I endoleaks in abdominal, thoracic or thoracoabdominal aortic aneurysm and are within the scope of the teachings of the present disclosure. Further, the stent of the present disclosure may also be applicable for use in peripheral vasculature, and any slight modifications or adaptations required for applications are within the scope of the present disclosure.
[38] The stent is designed with enhanced radial strength and anti-kinking properties to ensure long-term performance after deployment.
[39] In an embodiment, the stent includes a plurality of struts (hereinafter, struts) and multiple linkages. The struts are arranged in a plurality of circumferential rows in a pre-defined pattern to form a tubular structure. The plurality of rows of struts are interconnected by at least one linkage of the multiple linkages to form a plurality of open units and a plurality of closed units. In an embodiment, the multiple linkages include a plurality of first linkages (hereinafter, referred as first linkages), a plurality of second linkages (hereinafter, referred as second linkages) and a plurality of third linkages (hereinafter, referred as third linkages). In the depicted embodiment, the first linkages are configured to form the closed units in the stent, which has been explained later. And, the second linkages and the third linkages are configured to form the open units in the stent, which has been explained later.
[40] The plurality of linkages provides structural support to the stent. For example, the first linkages and the second linkages are configured to enhance the radial strength of the stent. Thereby, maintaining the shape of the stent against a vessel recoil or external forces, and preventing collapse of the stent post-deployment. In other words, the first linkages and the second linkages are configured to provide resistance to the stent against external compression (for example, pulsatile expansion during blood flow). Further, the first linkages and the second linkages are configured to improve anchorage of the stent to the vessel walls and the primary stent, thereby preventing migration of the stent post-deployment.
[41] The third linkages are configured to provide flexibility to the stent, allowing adaptability and conformity of the stent in a curved or torturous vessel in the body. The third linkages are configured to introduce anti-kinking property in the stent. Thereby, preventing formation of sharp curves or twists in the stent during or post deployment in the aortic vessel, which otherwise may cause collapse of the stent post-deployment and lead to migration of the stent.
[42] Thus, the plurality of linkages is configured to maximize the expansion of the stent and promote the structural integrity of the stent during and/or post deployment stages, thereby preventing blood leakage post-deployment.
[43] One of the proximal or distal portion of the stent is configured to be positioned into a lumen of a primary stent. For example, a proximal and/or distal end of the stent is configured to overlap with at least a proximal and/or distal portion of the primary stent. In endoleaks 1, the proximal portion of the stent is configured to be positioned into the lumen of the distal end of the primary stent. In endoleaks 3, the distal portion of the stent is configured to be positioned into the lumen of the proximal end of the primary stent. In an embodiment, the stent is designed to have a predefined outer diameter larger than an inner diameter of the lumen of the primary stent. This variation in diameter allows snug insertion of the proximal/distal portion of the stent into the respective lumen of the primary stent.
[44] Now referring to figures, Fig. 2a depicts an extension stent 200 (hereinafter, stent 200), according to an embodiment of the present disclosure. The stent 200 is a tubular structure having a proximal end 200a and a distal end 200b. In an embodiment, the stent 200 includes a proximal section 200c, a distal section 200d and a middle section 200e. The proximal section 200c and the distal section 200d are provided towards the proximal end 200a and the distal end 200b, respectively. The middle section 200e is sandwiched between (in other words, provided between) the proximal section 200c and the distal section 200d.
[45] The stent 200 is configured to undergo shape shifting and structural deformity, radially, between a collapsed state and an expanded state. For example, the stent 200 may be deformed to the collapsed state to load over a suitable delivery device (not shown). Upon delivering the stent 200 at an intended zone, the stent 200 is configured to regain its expanded state.
[46] The stent 200 may have a predefined length and a predefined diameter. In the collapsed state, the length of the stent 200 (hereinafter, collapsed length) may range between 30 mm and 100 mm. In the expanded state, the length of the stent 200 (hereinafter, expanded length) may range between 20 mm and 80 mm. In an embodiment, the collapsed length and the expanded length are 50 mm and 40 mm, respectively.
[47] In the collapsed state, the stent 200 has a collapsed inner diameter and a collapsed outer diameter. In the expanded state, the stent 200 has an expanded inner diameter and an expanded outer diameter.
[48] The stent 200 may have a uniform or non-uniform tubular structure. In the depicted embodiment, the stent 200 has a uniform tubular structure. In other words, an overall outer diameter of the stent 200 remains the same throughout a length. The expanded outer diameter of the stent 200 may vary based on the anatomical structure of the patient (i.e., the inner diameter of the aortic vessel) and an expanded inner diameter of the primary stent (not shown).
[49] The expanded outer diameter of the stent 200 is larger than the expanded inner diameter of the lumen of the primary stent with which the stent 200 overlaps. A proximal portion towards the proximal end 200a or a distal portion towards the distal end 200b is configured to be positioned into a lumen of a primary stent towards a proximal/ distal end of the primary stent. The proximal/distal portion of the stent 200 is configured to overlap with at least a proximal/ distal portion of the primary stent. In an embodiment, the proximal portion of the stent 200 is configured to be positioned into the lumen of the primary stent towards a distal end of the primary stent. The proximal portion of the stent 200 is configured to overlap with at least a distal portion of the primary stent. The length of the overlapping portion may vary depending upon the anatomical structure. The overlap between the proximal portion towards the proximal end 200a of the stent 200 and the distal portion of the primary stent provides a secure connection therebetween and ensures a continuous and leak-proof seal.
[50] The expanded diameter of the stent 200 is designed to be larger than the expanded inner diameter of the lumen of the primary stent, ensuring snug insertion of the proximal portion of the stent 200 into the portion of the lumen of the primary stent. The larger expanded outer diameter of the stent 200 provides a reinforcement against the expanded inner diameter of the primary stent and creates a tight seal therebetween, thereby preventing migration of the stent 200 from the primary stent. By creating a tighter seal between the stent 200 and the primary stent, the endoleaks are minimized.
[51] In an embodiment, the stent 200 is a mesh-like structure extending between the proximal end 200a and the distal end 200b. In an exemplary embodiment, the stent 200 includes a plurality of struts 230 (hereinafter, struts 230). The struts 230 may be formed using techniques, such as, without limitation, laser cut, 3-D printing, braiding technique, welding, machining, etc. In an embodiment, the struts 230 are formed using a laser cutting technique to form the mesh structure of the stent 200.
[52] The stent 200 may be a balloon expandable or self-expandable. In an embodiment, the stent 200 is self-expandable. The struts 230 may be made of shape memory, biocompatible materials, such as, without limitation, brasses, copper-aluminum, nickel-titanium (NiTi), etc., or a combination thereof. In an embodiment, the struts 230 are made of a nickel-titanium (NiTi) material. The shape memory of the struts 230 allows the stent 200 to shape shift and undergo structural deformity, radially, between the collapsed state (as shown in Fig. 2a) and the expanded state (as shown in Fig. 2b). Thus, the struts 230 made of shape memory materials allows the stent 200 to self-expand upon delivery. For example, the stent 200 may be deformed to the collapsed state to load the stent 200 over a suitable delivery device (not shown). In other words, in the collapsed state, the stent 200 is crimped, reducing the profile of the stent 200 for minimal invasive delivery. The collapsible nature allows the stent 200 to remain crimped while the stent 200 passes through the narrow delivery systems. Upon delivery of the stent 200 to a target site, the stent 200 is configured to regain its expanded state. The stent 200 expands to adapt and anchor with the wall of the aortic vessel without compromising its mechanical strength and structural integrity.
[53] Referring to Figs. 2c-2e, the stent 200 includes a plurality of rows of struts 230, as shown in Fig. 2c. In an embodiment, in each row, the struts 230 are joined to form alternating peaks (p) and troughs (t). The struts 230 of each row may be arranged in a predefined pattern, such as, curved chevron pattern, zig-zag pattern, chevron pattern, etc. In an embodiment, the struts 230 of each row are formed continuously in a curved chevron pattern. Each strut 230 may have a straight profile or curved profile. In an embodiment, each strut 230 has a curved profile. The continuous curved chevron pattern of the struts 230 gives a near appearance of cuspidate shape of an apex of a leaf.
[54] The rows of the struts 230 are arranged parallelly. In an embodiment, the peaks (p) of one row are aligned with the troughs (t) of an adjacent row, as shown in Fig. 2c. The plurality of rows of the struts 230 extend in a circumferential direction and are coupled to form a tubular structure of the stent 200.
[55] The stent 200 includes multiple types of linkages. The multiple types of linkages are configured to interconnect two adjacent rows of struts 230. In an embodiment, the multiple types of linkages include a plurality of first linkages 217 (hereinafter, referred as first linkages 217), a plurality of second linkages 220 (hereinafter, referred as second linkages 220) and a plurality of third linkages 240 (hereinafter, referred as third linkages 240).
[56] In an embodiment, the plurality of rows of struts 230 provided in the proximal section 200c and in the distal section 200d are interlinked to form a plurality of closed units (201, 203) (hereinafter, the closed units (201, 203)) in the stent 200. The proximal section 200c may include 2 to 4 number of rows of struts 230. In an embodiment, the proximal section 200c includes 2 rows of struts 230. Similarly, the distal section 200d includes 2 rows of struts 230, though they may include 2 to 4 number of rows of struts 230.
[57] The first linkages 217 are configured to interlink one trough (t) of one row of struts 230 with a peak (p) of an adjacent row of struts 230 in the proximal section 200c and distal section 200d of the stent 200. In an embodiment, the first linkages 217 are configured to interconnect two adjacent rows of struts 230 provided at the proximal end 200a. In an exemplary embodiment, each trough (t) of a first row of struts 230 is linked with an adjacent peak (p) of an adjacent second row of struts 230 via the first linkages 217. Thus, forming closed units 201 at the proximal end 200a. Similarly, the first linkages 217 are configured to interconnect two adjacent rows of struts 230 provided at the distal end 200b to form closed units 203.
[58] The first linkage (217) may have a predefined shape, including, but not limited to, straight linkage, curved linkage, angled linkage, s-shaped linkage, diamond shape linkage, zigzag linkage, spiral (coiled) linkage, etc. In the depicted embodiment, the first linkage (217) is a diamond shaped linkage forming the closed unit (201, 203), as shown in Fig. 2d. In the depicted embodiment, the struts 230 of the closed units (201, 203) have a non-uniform strut width because of the first linkage (217). In the depicted embodiments, each closed unit (201, 203) includes an apiculate leaf-like structure. Each closed unit (201, 203) may include at least 02 to 08 number of struts 230. In the depicted embodiment, each closed unit (201, 203) includes 04 number of struts 230.
[59] The closed units (201, 203) at the proximal end 200a and at the distal end 200b provide stability to the stent 200 within the aortic vessel and the primary stent. The closed units (201, 203) at the proximal end 200a and the distal end 200b provides uniform sealing within the aortic vessel and with the lumen of the primary stent, respectively. Further, the closed units (201, 203) provide rigidity at the proximal end 200a and the distal end 200b of the stent 200. Thereby, minimizing the risk of migration, especially in cases leading to endoleaks type I.
[60] The first linkages 217 enhance radial strength at the proximal end 200a and the distal end 200b of the stent 200. The first linkages 217 allow uniform expansion of the ends of the stent 200 during the deployment. The first linkages 217 allows the stent 200 to conform with the aortic vessel and the distal portion of the primary stent, respectively. Thereby, maintaining the shape of the stent against a vessel recoil or external forces, and preventing collapse of the stent post-deployment. In other words, the first linkages 217 are configured to provide resistance to the stent against external compression (for example, pulsatile expansion during blood flow).
[61] The plurality of rows of struts 230 provided in the middle section 200e are interlinked to form a plurality of open units (205). The middle section 200e may include 04 to 12 number of rows of struts 230. In an embodiment, 8 rows of struts 230 are provided in the middle section 200e of the stent 200 (i.e., between the closed units 201, 203).
[62] In an embodiment, the second linkages 220 are configured to interlink one peak (p) of one row of struts 230 with a corresponding trough (t) of an adjacent row of struts 230 in the middle section 200e of the stent 200. In the depicted embodiment, every third peak (p) of one row of struts 230 is linked with a corresponding trough (t) of an adjacent row of struts 230 via the second linkage 220.
[63] The second linkage (220) may be a straight linkage, curved linkage, angled linkage, s-shaped linkage, diamond shape linkage, zigzag linkage, spiral (coiled) linkage, etc. In the depicted embodiment, the second linkages (220) are straight linkages. The second linkages 220 provide radial strength to the stent 200 and prevent foreshortening of the stent 200 during the deployment and post-deployment.
[64] In an embodiment, the third linkages 240 are configured to interlink one trough (t) of one row of struts 230 with a corresponding peak (p) of an adjacent row of struts 230 in the middle section 200e of the stent 200. In the depicted embodiment, every third trough (t) of one row of struts 230 is linked with a corresponding peak (p) of an adjacent row of struts 230 via the third linkage 240. Other arrangements are possible like alternate peaks of the adjacent rows may be joined.
[65] The third linkage (240) may be a straight linkage, curved linkage, angled linkage, s-shaped linkage, diamond shape linkage, Zigzag linkage, spiral (coiled) linkage, etc. In the depicted embodiment, the third linkages (240) are s-shaped linkages. The third linkage 240 introduces anti-kinking in the stent 200 (in other words, the third linkages 240 prevent kinking of the stent 200). The third linkage 240 of the stent 200 prevents formation of sharp curves or twists in the stent 200 during or post deployment in the aortic vessel, which otherwise may cause collapse of the stent 200 post-deployment and lead to migration of the stent 200.
[66] In an embodiment, the second linkages 220 and the third linkages 240 are configured to form plurality of open units 205 (hereinafter, referred as open units 205). The open units 205 extend between the closed units (201, 203) provided at the proximal end 200a and distal end 200b, respectively of the stent 200. Each open unit 205 may include at least 8 to 16 number of struts 230. In the depicted embodiment, each closed unit (201, 203) includes 12 number of struts 230.
[67] Two adjacent rows of struts 230 provided in the middle section 200e of the stent 200 may be interlinked by one of the second linkages 220 or the third linkages 240 to form the open units 205. The selection of interlinking peaks (p) of one row of struts 230 with a trough (t)/ peak (p) of an adjacent row may depend upon the requirement of the radial strength and anti-kinking property in the stent 200.
[68] Each closed unit (201) includes an extension 210, as shown in Fig. 2c. The extension 210 has a predefined shape, such as, but not limited to diamond shape, c shape, crown shape, U shape, etc. In an embodiment, the extension 210 has an elongated crown shape. The extension 210 enhances fixation of the stent 200 with the vessel wall and the expanded primary stent. Thus, helps maintaining the position of the stent 200 at its deployed location. The extensions 210 provide additional support to the stent 200 in the deployed state. This ensures anchorage of the stent 200 within the vessel wall and the expanded primary stent. The extensions 210 have smooth surface that prevents rupturing of the vessel wall.
[69] In an embodiment, the stent 200 includes two or more marker cavities 210a provided on the extension 210. Each extension 210 may be provided with a marker cavity 210a. In the depicted embodiment, a marker cavity 210a is provided on one extension 210, followed by two extensions 210 without a marker cavity 210a. Other arrangements of marker cavity 210a in extensions 210 are possible. Each marker cavity 210a may be a slot, hole, groove, etc. Each marker cavity 210a may include a shape, such as, but not limited to, circular, triangular, ellipse, square, rectangle, ellipse, pyramid, etc. In an embodiment, each marker cavity 210a have a circular shape.
[70] Each marker cavity 210a may be coupled to a marker. The marker may be a radiopaque marker or components that are visible under medical imaging, helping healthcare providers in accurately positioning the stent 200 at the target site. In an embodiment, each marker cavity 210a is coupled to a corresponding radiopaque marker (not shown) having a corresponding shape by using techniques, such as, without limitation, welding, riveting, crimping, clamping, hooking, brazing, mechanically, laser cutting, etc. In an exemplary embodiment, each marker cavity 210a is welded to a corresponding radiopaque marker by using welding technique.
[71] Referring to Fig. 2d depicts the stent 200 in the expanded state. In an embodiment, a strut 230 in each open unit (205) has a horizontal length A. The horizontal length A of each strut 230 may range between 2.0 mm and 4.0 mm. In an embodiment, the horizontal length A of each strut 230 is 2.88 mm. Two adjacent struts 230 are joined/coupled at a predefined angle B to form a trough(t). The angle B may range between 25° and 45°. In an embodiment, the angle B is 37°. Each strut 230 has a width C that may range between 220 microns and 300 microns. In an embodiment, the width C is 260 microns.
[72] Two adjacent struts 230 are joined at a predefined angle F to form a peak (p). The angle F may range between 125˚ and 145˚. In an embodiment, the angle F is 137 degrees. Each strut 230 has an inclined length G. The inclined length G of each strut 230 may range between 2.50mm and 4.50mm. In an embodiment, the inclined length G of each strut 230 is 3.18 mm. The first linkage 217 may have a horizontal length H ranging between 1.00mm and 2.00mm. In an embodiment, the horizontal length H of each first linkage 217 is 1.35 mm. Each open unit (205) has a horizontal length I that may range between 4.00mm and 8.00mm. In an embodiment, the horizontal length I each open unit (205) is 6.45 mm. In an embodiment, each peak (p) and each trough (t) of the open units (205) have the same curved profile. A width J of the curved profile of a strut 230 at each peak (p) and each trough (t) may range between 270micron and 330micron. In an embodiment, the width J is 300 microns.
[73] Referring fig. 2e, each open unit (205) includes a vertical length K that may range between 5.00mm and 10.0mm. In an embodiment, the vertical length K of each open unit (205) is 7.68mm. A width L of each second linkage 220 may range between 220 microns and 260 microns. In an embodiment, the width L of each second linkage 220 is 245 microns. A distance M between a peak (p) of one row and a trough (t) of an adjacent row of the struts 230 may range between 0.30mm and 0.70mm. In an embodiment, the distance M between a peak (p) of one row and a trough (t) of an adjacent row of the struts 230 is 0.5 mm.
[74] Each extension 210 includes an elongated crown having a circular base. The elongated crown of the extension 210 without marker cavity 210a has a curved profile. The curved profile has a radius O ranging between 0.50mm and 0.80mm. In an embodiment, the radius O of the curved profile of the elongated crown is 0.67mm. Each closed unit (201) has a horizontal length P that may range between 5.00mm and 15.0mm. In an embodiment, the horizontal length P of each closed unit (201) is 10.40mm. The marker cavity 210a includes a radius Q that may range between 0.15mm and 0.35mm. In an embodiment, radius Q of the marker cavity 210a is 0.25mm. In an embodiment, each extension 210 provided with a marker cavity 210a, has a circular shape having a radius R. The radius R may range between 0.45 mm and 0.65mm. In an embodiment, the radius R of each extension 210 with the marker cavity 210a is 0.57mm. Each first linkage 217 may have a width S ranging between 0.45mm and 0.65mm. In an embodiment, the width S of each first linkage 217 is 0.56mm. A radius T of the circular base may range between 0.2mm and 0.6mm. The radius T of the circular base of the extension 210 is 0.4mm. The third linkage 240 may have a width U ranging between 250microns and 650microns. In an embodiment, the width U of the third linkage 240 is 400 microns.
[75] Additionally, the stent 200 may include at least one flared portion 200f. At least one of the proximal section 200c or the distal section 200d may include the flared portion 200f. At least one of the plurality of closed units (201,203) towards the proximal end (200a) or the distal end (200b) include a flared portion 200f. The flared portion 200f of the stent 200 is configured to provide a large surface area to anchor the stent 200 in the aortic vessel. The flared portion 200f ensures a continuous and leak-proof seal between the stent 200 and the vessel wall. As shown in Fig. 2f, the closed units 203 in the distal section 200d includes a flared portion 200f, according to an embodiment of the present disclosure.
[76] Fig. 3 illustrates a method 300 of fabricating the stent 200, according to an embodiment of the present disclosure.
[77] At step 302, a tubing is provided, for which a suitable material is chosen. The tubing may be made of biocompatible material, such as, without limitation, brasses, copper-aluminum, nickel-titanium (NiTi), etc., or a combination thereof. In an exemplary embodiment, the tubing made of nickel-titanium (NiTi) is chosen. Dimensions (such as length, inner diameter, outer diameter, thickness, etc.) of the tubing are chosen based upon desired dimensions of stent 200.
[78] At step 304, a digital design of the stent 200 is prepared using a computer aided design (CAD) software. Any known CAD software such as, AutoCAD, Adobe Illustrator, Solidworks, Onshape, Inkspace, Sketchup, etc., may be used to prepare the digital design. A variety of data and information may be input into the CAD software to prepare the digital design. Examples of the data and information input into the CAD software include, without limitation, material and dimensions of the tubing, dimensions of the stent 200 (for example, size, shape, positioning, pattern of the plurality of struts 230, the plurality of linkages, etc.).
[79] The CAD software generates digital models that represent the physical components. These models include precise measurements, dimensions and specifications. The CAD software can stimulate and analyze the behavior of designs under various conditions. This helps in identifying potential issues and allows for optimization before physical fabrication. The user may select an optimal design (e.g., the digital design) in the CAD software. In an embodiment, Computer Aided Manufacturing (CAM) software is integrated with the CAD software or vice versa. The CAM software interprets the digital design to generate machine toolpath data used during the fabrication process. The machine toolpath data may guide subsequent processes such as, cutting, shaping process, etc.
[80] At step 306, the digital design is loaded into software for controlling a laser cutting machine. The software for controlling the laser cutting machine may be installed on a computer communicatively coupled with the laser cutting machine using a suitable interface. The control software ensures that the fabrication process is accurate and matches the design configured by the operator. One or more process configurations may be set by the operator into the control software as per requirements. The one or more process configurations include, without limitation, power of a laser beam, frequency of the laser beam, cutting speed of the laser beam, focus of the laser beam, pressure of an assist gas, lubricant pressure. The one or more process configurations may be decided based on the material and design requirements. In an embodiment, a gas, such as, without limitation, argon, oxygen, nitrogen, etc., may be used as the assist gas. In an embodiment, the frequency of the laser beam ranges from 4000 kHz to 5000 kHz. In an embodiment, the duration of the laser beam pulse ranges between 12 ms and 15 ms. In an embodiment, the output power of the laser beam ranges between 80 W and 90 W. In an exemplary implementation, the frequency, pulse duration and output power of the laser beam are 4750 Hz, 13 ms and 85 W, respectively. In an embodiment, argon is used as the assist gas having a pressure ranging between 1.2 atm and 1.6 atm. In an exemplary implementation, argon is used at a pressure 1.4 atm.
[81] At step 308, the tubing is machined as per the digital design of the stent 200 prepared at the step 306, to maintain dimensional accuracy of the layers during the fabrication process. The tubing may be machined using various methods, such as, without limitation to, casting, computer numerical control machining (CNC machining), laser cutting, etc. In an embodiment, the tubing is machined using the laser cutting machine. The tubing is passed through a bush into a laser cutting chamber. One end of the tubing is held by a chuck placed inside the laser cutting chamber. The other end of the tubing is held by a tube holder. A gas pipeline extends from a gas cylinder having the assist gas and is attached to the laser cutting machine. An appropriate pressure is set. The laser cutting machine is then turned ON.
[82] The laser cutting machine follows the toolpath instructions precisely and cuts the tubing using a laser beam. The laser beam is a high energy beam that vaporizes or melts the material of the tubing at the designated point. The laser cutting machine is controlled by the control software loaded on the computer as per the digital design and the set parameters. Thus, the laser cutting machine at this step removes undesired material of the tubing as per the digital design of the stent 200. Once the machining is complete, the stent 200 is formed. In the depicted embodiment, the stent 200 is formed having two or more marker cavities 210a in the form of circular holes.
[83] At step 310, the machined tube obtained from the step 608 is subjected to a heat-setting step. Subjecting the stent 200 to the heat-setting step helps in setting the shape of the stent 200 in an expanded state. Further, heat-setting helps in maintaining the shape memory and mechanical properties of the stent 200. In an optional embodiment, the heat-setting step helps in providing a flare to the stent 200.
[84] To shape-set the stent 200, the stent 200 may be held or clamped onto a suitable mandrel to ensure precise shape setting of the stent 200 during the heat-setting step. The selection of the mandrel depends on the desired stent geometry.
[85] For example, to achieve a uniform tubular structure of the stent 200, a straight mandrel is used to maintain consistent dimensions throughout the length of the stent 200. In a depicted embodiment, the stent 200 is held to the first mandrel 400, as shown in Fig. 4a. The first mandrel 400 has a uninform outer diameter that corresponds to the expanded inner diameter of the stent 200.
[86] Similarly, if the stent 200 is to be flared, a mandrel with a corresponding contour is chosen to achieve the desired flare in the stent 200. In one depicted embodiment, the stent 200 is held to a second mandrel 450, as shown in Fig. 4b. The second mandrel 450 has a first portion 450a and a second portion 450b. An outer diameter of the first portion 450a is different from an outer diameter of the second portion 450b. In the depicted embodiment, the first portion 450a is narrower than the second portion 450b of the second mandrel 450. The outer diameter of the first portion 450a corresponds to the expanded inner diameter of the proximal portion of the stent 200 towards the proximal end 200a. The outer diameter of the second portion 450b corresponds to the expanded inner diameter of the distal portion of the stent 200 towards the distal end 200b (in other words, the portion (proximal/distal) that is intended to be flared, is provided on the second portion 450b of the second mandrel 450).
[87] Thereafter, the stent 200 is subjected to a first predefined temperature for a first predefined time period. In an embodiment, the first predefined temperature ranges between 500 degrees Celsius and 510 degrees Celsius for the first predefined period of time ranging between 02 min and 06 min. In an exemplary embodiment, the stent 200 is subjected to the first predefined temperature at 505 degrees Celsius for 05 minutes.
[88] Thereafter, the stent 200 is allowed to cool down for a second predefined time period. The second predefined time period may range between 01 minutes to 03 minutes. In an embodiment, the stent 200 is allowed to cool down for 02 minutes. This helps relieve internal stress, which can develop in the material during heat treatment, ensuring that the stent 200 does not fail or break during further use.
[89] The stent 200 is finalized after the machining step at 312. The stent 200 is finalized using at least one of a grinding, a sand-blasting and/or an electropolishing process. First, the stent 200 is subjected to a grinding process. After the machining process, burrs and deformities may form over the surface of the stent 200. The grinding process is employed to remove those burrs and deformities and achieve the desired surface finish and dimensional accuracy.
[90] Next, the stent 200 is subjected to a sandblasting process to remove any microscopic burrs remaining on the surface of the stent 200 after subjecting the stent 200 to the grinding process. In an embodiment, during the sandblasting process, a media of an abrasive material, such as, but not limited to, sand, glass beads, aluminum oxide, steel shot, etc. are propelled at high velocity on the surface of the stent 200 using compressed air or pressured gas. The abrasive material may be chosen based on the desired surface finish and the material of the stent 200. In an exemplary embodiment, aluminum oxide is chosen as the media. The media is loaded into a sandblasting equipment. The sandblasting equipment includes a sandblasting chamber and a nozzle that blasts the media out of the sandblasting chamber and a dust collection system. The pressure of the compressed air (or gas) and the nozzle is adjusted so as to control the velocity and direction of the media. In an embodiment, the air pressure is adjusted within the range of 1.5 bar to 3.5 bar. In an embodiment, the flow pressure of the media may be in the range of 1.5 bar to 3.5 bar. The frequency with which the abrasive particles are propelled onto the stent 200 is controlled so as to achieve the desired smoothness on the surfaces of the stent 200. In an embodiment, the frequency varies between 0 Hz to 0.5 Hz. The stream of the media is directed onto surface of the stent 200 using the nozzle. In an exemplary embodiment, the air pressure, flow pressure of the media and the frequency are 2.5 bar, 2.5 bar and 0 Hz, respectively. In order to achieve uniform results, the nozzle is moved evenly and consistently across the surface of the stent 200. This results in finely smooth surface of the stent 200, that is ready for subsequent processes.
[91] The stent 200 is thereafter, subjected to an electro-polishing process. Electro-polishing is an electrochemical process that is employed to eliminate any impurities or contaminants and sharp edges remaining on the stent 200 after the sandblasting process. One or more operating parameters of the electropolishing process may be controlled as per requirement. The one or more operating parameters may include current and voltage applied by a power supply, time period (i.e., the time for which the stent 200 is immersed in the electrolytic bath) and the number of cycles (each cycle lasts for one time period). The pre-defined current ranges between 0.5 Amp to 1.5 Amp. The pre-defined voltage ranges between 5 V to 15 V. The pre-defined time period ranges between 1 minute to 3 minutes. The pre-defined number of cycles ranging between 2 and 6 may be performed. In an exemplary embodiment, the pre-defined current, the pre-defined voltage, the pre-defined time period and the pre-defined number of cycles are 0.9 Amp, 9 V, 2 min and 4, respectively.
[92] At step 314, the one or more markers are coupled to the stent 200. In the depicted embodiment, each marker is fit into the corresponding marker cavity 210a and is welded to the stent 200 using laser technique. This ensures secure fixation of each marker within the corresponding marker cavity 210a without compromising the structural integrity of the stent 200. One or more operating parameters of the welding process may be controlled as per requirement. The one or more parameters of the welding process may include voltage applied by a power supply, pulse duration (i.e., duration of each laser pulse during the welding process), frequency (i.e., number of laser pulse per second), spot diameter (i.e., the diameter of the laser beam at point of contact with the marker and marker cavity 210a of the stent 200). The predefined voltage may range between 220V to 260V. The predefined pulse duration and frequency may range between 0.5 ms and 1.5 ms, and 0 Hz and 1 Hz, respectively. The spot diameter may range between 0.05 mm and 0.15 mm. In an exemplary embodiment, the predefined voltage, the predefined pulse duration, frequency and the spot diameter are 240V, 01 ms, 0 Hz and 0.10 mm, respectively.
[93] Fig. 5 illustrates a flowchart of a method 500 of delivering the stent 200 at a targeted region in the aortic vessel, according to an embodiment of the present disclosure.
[94] At step 502, the stent 200 is preloaded within a delivery system.
[95] An exemplary delivery system 600 is illustrated in Fig. 6. The delivery system 600 includes a proximal end 600a, a distal end 600b and a distal tip 600c. In the depicted embodiment, the delivery system 600 includes a catheter. The catheter includes an outer sheath 602, an inner sheath 604 and a holding member 606. The outer sheath 602 has a tubular structure extending between the proximal end 600a and the distal end 600b. The outer sheath 602 is hollow from inside and defines a lumen. The inner sheath 604 has a tubular structure extending between the proximal end 600a and the distal end 600b. The inner sheath 604 is disposed within the lumen of the outer sheath 602. The holding member 606 may be provided at the distal end 600b of the delivery system 600. The holding member 606 is disposed between the outer sheath 602 and the inner sheath 604 at the distal end 600b of the delivery system 600. The holding member 606 may also be provided at the distal tip 600c of the delivery system 600. The holding member 606 may be a pusher tip or a retractable clasp.
[96] For the purpose of loading the stent 200 within the delivery system 600, the stent 200 is crimped into the collapsed state.
[97] The stent 200 is loaded at the distal end 600b of the delivery system 600. The stent 200 is mounted on an outer surface of the inner sheath 604. In other words, the stent 200 is disposed between the inner sheath 604 and the outer sheath 602 at the distal end 600b. The outer sheath 602 is configured to retain the stent 200 in the collapsed state during navigation. The proximal end 200a of the stent 200 is coupled to the holding member 606. A proximal end of the holding member 606 may be provided with one or more anchoring element (not shown). The one or more anchoring element helps in anchoring the stent 200 with the holding member 606. The holding member 606 is configured to provide additional support to the collapsed stent 200 until the outer sheath 602 is retracted during the deployment. The holding member 606 is configured to prevent premature deployment of the stent 200.
[98] At step 504, the distal tip 600c of the delivery system 600 is introduced into the femoral artery of the patient and is advanced through the intricate pathways of the vessel. The distal tip 600c includes a smooth surface that reduces trauma to the vessel as the delivery system 600 is advanced. It may have a tapered or atraumatic design for ease of navigation.
[99] For the purpose of maneuvering the distal end 600b delivery system 600 in the blood vessel, the proximal end 600a of the delivery system 600 may be coupled to a handle 650 (as shown in Fig. 06). The handle 650 allows the operator to manipulate and maneuver the delivery system 600 within the vasculature system during the navigation. Further, the handle 650 helps in deploying the stent 200 at the target site. In the depicted embodiment, the handle 650 includes a luer hub 652, a hemostatic hub 654 and a one-way stop cock 656.
[100] A guidewire (not shown) is inserted into the lumen of the inner sheath 604 through the luer hub 652. The guidewire helps to position the distal end of the catheter of the delivery system 600 to the target site. The guidewire is introduced into the femoral artery of the patient and is advanced towards the target site through the intricate pathways of the vessel. Thereafter, the catheter of the delivery system 600 is advanced in the vasculature to the target site of the primary stent graft, using fluoroscopic guidance. The distal tip 600c of the catheter follows the guidewire to reach the target site. In an embodiment, the catheter may include one or more markers (not shown). The one or more markers may be provided along a length of the outer sheath 602. The one or more markers of the delivery system 600 help the operator visualize the position of the delivery system 600 using imaging techniques. The one or more markers ensure accurate placement and deployment of the stent 200 at the target site.
[101] The hemostatic hub 654 prevents blood leakage and stagnation, minimizing blood loss during procedures involving catheter insertion and removal. A fluid (such as, saline) is provided at the target site via the one-way stop cock 656.
[102] At step 506, upon reaching the target position, the distal tip 600c of the delivery system 600 is aligned with a tip of the guidewire with the help of fluoroscopic imaging techniques. Upon alignment of the catheter at the target site, the outer sheath 602 is gradually retracted with the help of the handle 650, exposing the stent 200, as shown in Fig. 7a. The handle 650 may be provided with a mechanism (not shown) for the retraction of the outer sheath 602. The stent 200 remains stationary while the outer sheath 602 is pulled back (in the proximal direction) allowing the stent 200 to expand and engage with the vessel wall. For example, a slight retraction of the outer sheath 602 exposes the distal end 200b of the stent 200. Upon exposure, the distal end 200b expands and secures tight seal with the vessel wall. An entire length of the stent 200 gradually expands upon retracting the outer sheath 602 further.
[103] As shown in Fig. 7b, in the depicted embodiment, as the stent 200 expands the distal portion of the stent 200 secures tight seal with the vessel wall. And, the proximal portion of the stent 200 overlaps over a distal portion of the primary stent and secure a tight seal therewith. The stent 200 extends the coverage length from the distal end of the primary stent into healthy portions of the aortic wall. Thereby, preventing blood leakage into the aneurysm site post-expansion.
[104] At step 508, the proximal end 200a of the stent 200 is detached from the one or more anchoring members of the holding member 606 using any suitable mechanism that may be provided in the handle 650. Thereafter, the delivery system 600 is retracted in the proximal direction and is removed from the patient’s body.
[105] 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. , C , C , Claims:WE CLAIM:
1. A stent (200) having a proximal section (200c) and a distal section (200d) sandwiching a middle section (200e), the stent (200) includes:
a) a plurality of rows of struts (230) extending circumferentially to form:
a. a plurality of closed units (201,203) towards the proximal end (200a) and the distal end (200b);
b. a plurality of open units (205) in the middle section (200e);
b) a plurality of first linkages (217) configured to interlink two adjacent rows of struts (230) of the proximal section (200c) and distal section (200d) to form the plurality of closed units (201, 203);
c) a plurality of second linkages (220) configured to interlink one peak (p) and one trough (t) of two adjacent rows of struts (230); and
d) a plurality of third linkages (240) configured to interlink one trough (t) and one peak (p) of two adjacent row of struts (230);
wherein, two adjacent rows of struts (230) provided in the middle section (200e) of the stent (200) are interlinked by one of the second linkage (220) or the third linkage (240) to form the plurality of open units (205).
2. The stent (200) as claimed in claim 1, wherein at least one of the plurality of closed units (201,203) towards the proximal end (200a) or the distal end (200b) include a flared portion (200f).
3. The stent (200) as claimed in claim 1, wherein the plurality of rows of struts (230) are arranged in a circumferential direction to form a tubular structure of the stent (200).
4. The stent (200) as claimed in claim 1, wherein each strut (230) of the plurality of rows of struts (230) has one of a straight profile or a curved profile.
5. The stent (200) as claimed in claim 1, wherein struts (230) of each row of the plurality of rows of struts (230) are arranged in one of a predefined curved chevron pattern, a zig-zag pattern, or a chevron pattern.
6. The stent (200) as claimed in claim 1, wherein the plurality of first linkages (217) are configured to interlink each trough (t) of a first row of struts (230) with an adjacent peak (p) of an adjacent second row of struts (230).
7. The stent (200) as claimed in claim 1, wherein the plurality of first linkages (217) is one of a straight linkage, a curved linkage, an angled linkage, a s-shaped linkage, a diamond shape linkage, a zigzag linkage or a spiral (coiled) linkage.
8. The stent (200) as claimed in claim 1, wherein each closed unit (201, 203) includes an apiculate leaf-like structure.
9. The stent (200) as claimed in claim 1, wherein each closed unit (201, 203) includes 2 to 8 struts (230).
10. The stent (200) as claimed in claim 1, wherein the plurality of second linkages (220) are straight linkages configured to provide radial strength to the stent (200).
11. The stent (200) as claimed in claim 1, wherein the plurality of third linkages (240) are s-shaped linkages configured to prevent kinking of the stent (200).
12. The stent (200) as claimed in claim 1, wherein each closed unit (201, 203) includes:
a) an extension (210);
b) two or more marker cavities (210a) provided on the extension (210)
wherein, each marker cavity (210a) is coupled to a marker.
13. The stent (200) as claimed in claim 1, wherein each strut (230) of the plurality of rows of struts (230) includes:
a) a horizontal length (A) ranging between 2.0 mm and 4.0 mm;
b) a width (C) ranging between 220 microns and 300 microns; and
c) an inclined length (G) ranging between 2.50mm and 4.50mm.
14. The stent (200) as claimed in claim 1, wherein in an expanded state of the stent (200), two adjacent struts (230) of the plurality of rows of struts (230), are coupled to form one of:
a) a trough(t) joined at a predefined angle B ranging between 25° and 45°;
b) a peak (p) joined at a predefined angle F ranging between 125˚and 145˚.
15. The stent (200) as claimed in claim 1, wherein each open unit (205) has
a) a horizontal length (I) ranging between 4.00mm and 8.00mm
b) a vertical length (K) ranging between 5.00mm and 10.0mm.
16. The stent (200) as claimed in claim 1, wherein each first linkage (217) has a horizontal length (H) ranging between 1.00mm and 2.00mm.
17. The stent (200) as claimed in claim 1, wherein each second linkage (220) includes a width (L) ranging between 220 microns and 260 microns.
18. The stent (200) as claimed in claim 1, wherein each peak (p) of one row and a trough (t) of an adjacent row of the struts (230) includes a distance (M) ranging between 0.30mm and 0.70mm.
19. A method (300) of fabricating a stent (200), comprising:
a) providing a tubing of a biocompatible material;
b) machining the tubing as per a digital design of a stent (200);
c) heat-setting the machined tube for setting shape of the stent (200) in an expanded state, at a first predefined temperature for a first predefined time period; and
d) finalizing the stent (200) using at least one of a grinding, a sand-blasting or an electro-polishing process.