BILLOWING GRAFT ASSEMBLIES FORMED FORM ONE OR MORE ADVANTAGEOUSLY SELECTED STRUCTURAL FEATURES
A prosthetic device for the treatment of an anatomic organ in a patient is provided. The prosthetic device includes a main body having a height and a circumference and formed from a plurality of circumferentially extending wires and configured for being received in the organ of the patient, wherein the main body defines a portion extending along a length thereof that has a reduced hoop stress relative to the remainder of the main body when in a relaxed state and a covering extending over the main body and forming a billowing recess along the length of the frame in the main body due to the portion having reduced hoop stress. The anatomic organ may be an aorta of a patient.
This application claims the benefit of U.S. utility patent application Ser. No. 14/551,103, titled “Variable Depression Stents (VDS) and Billowing Graft Assemblies,” filed on Nov. 24, 2014, which further claims the benefit of PCT Application No. PCT/US14/41185 filed on Jun. 5, 2014, which claims the benefit of each of U.S. provisional patent applications: 61/831,196, titled “Suprarenal Endograft and Method,” filed on Jun. 5, 2013; 61/863,745, titled “Variable Depression Stent with Billowing Graft,” filed on Aug. 8, 2013; 61/879,928, titled “Suprarenal Endograft with Variable Depression Stent,” filed on Sep. 19, 2013; 61/940,866, titled “Endograft Adaptable for use in Multiple Locations of Abdominal Aorta,” filed on Feb. 18, 2014; 61/940,865, titled “Suprarenal Endograft with Variable Depression Stent,” filed on Feb. 18, 2014; 62/001,916, titled “Variable Depression Stents (VDS) and Billowing Graft Assemblies”, filed on May 22, 2014; and 61/940,327, titled “Branched Aortic Graft and Method of Using the Same”, filed on Feb. 14, 2014, all of which are incorporated herein in entirety by this reference. This application further claims benefit of PCT Application No. PCT/US15/15959 filed on Feb. 13, 2015, titled “Billowing Graft Assemblies Formed From One or More Advantageously Selected Structural Features,” which claims the benefit of U.S. Provisional Patent Application No. 61/940,867 filed on Feb. 18, 2014 entitled “Stent having Selective Structural Properties at a Portion thereof and Method for Making the Same,” the contents of which are incorporated in entirety by this reference.
TECHNICAL FIELDThe present disclosure relates to devices that may be used to treat aortic aneurysms. The devices described may also be used for the treatment of thoracoabdominal, arch and ascending aneurysms.
BACKGROUNDEndovascular technology has revolutionized the treatment of abdominal aortic aneurysms. This technology has shifted the treatment of these deadly disorders from an invasive, morbid operation to a minimally invasive option with low morbidity and mortality and length of stay. Although many patients are candidates for this less invasive repair with conventional devices, a large group of patients are not treatable because of anatomical restrictions. Some of these patients may be candidates for treatment with conventional fenestrated endografts, however there are significant limitations to the use of that technology. These limitations are often secondary to poor iliofemoral access (because of the large profile of the current devices), angulations in the aorta, the degree of angulation and disease within the renal arteries, technical limitations with regard to the creation of the holes in the current endografts or a combination thereof. Another limitation to the current available technology is the fact that a device may need to be created for each individual patient, adding delays of between three to six weeks to the treatment of the patients and patients with urgent/emergent needs would be ineligible for this treatment.
These stents have sufficient structural rigidity that they do not collapse once implanted within a patient, yet must also have sufficient expansion properties that they can be inflated during operation into an expanded state from the less invasive contracted state they are in during operation. Additionally, the stents must mimic the flexibility of the portion of the artery that they are being inserted in, often times requiring flexible tortuosity in order to maintain proper blood flow and to reduce the risk of compression and kinking.
Stents typically are formed by selecting one material that forms each portion of the material used to form the stent frame. The material can be sized according to a desired diameter or shape, but selection of characteristics for use in stent design is limited. In certain instances, having a selected radial or axial strength is desired.
SUMMARYThis summary is provided to introduce in a simplified form concepts that are further described in the following detailed descriptions. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it to be construed as limiting the scope of the claimed subject matter.
A stent assembly according to at least one embodiment includes a first support ring, a second support ring, and a billowing graft. Each support ring may be made of shape memory wire, stainless steel, or other materials. The first support ring has interconnected circumferentially alternating first inner prongs and first outer prongs, the first inner prongs defining a first inner diameter around a central longitudinal axis, and the first outer prongs defining a first outer diameter around the central longitudinal axis greater than the first inner diameter. The second support ring is spaced from the first support ring along the central longitudinal axis. The second support ring has interconnected circumferentially alternating second inner prongs and second outer prongs, the second inner prongs defining a second inner diameter around the central longitudinal axis, and the second outer prongs defining a second outer diameter around the central longitudinal axis greater than the second inner diameter. The billowing graft engages the first support ring and second support ring, the billowing graft following a waving peripheral path at least partially around at least one of the first support ring and second support ring.
In at least one example, a circumferential position of a particular first inner prong is aligned with a circumferential position of a particular second inner prong, and circumferential positions of two first outer prongs adjacent the particular first inner prong are aligned respectively with circumferential positions of two second outer prongs adjacent the particular second inner prong such that a longitudinal channel is defined along the aligned circumferential positions of the particular first inner prong and particular second inner prong.
In at least one example, the billowing graft billows along the longitudinal channel
In at least one example, the billowing graft is attached to the two first outer prongs adjacent the particular first inner prong and to the two second outer prongs adjacent the particular second inner prong.
In at least one example, the billowing graft is free to billow radially outward from and radially inward toward the particular first inner prong and the particular first inner prong along the longitudinal channel.
In at least one example, the first inner prongs have tips directed in a first longitudinal direction; and the first outer prongs have tips directed in a second longitudinal direction opposite the first longitudinal direction.
In at least one example, the first support ring further has a radially flat portion defined by at least two prongs that extend in opposite longitudinal directions, the at least two prongs of the radially flat portion of the first support ring being equidistant from the central longitudinal axis.
In at least one example, the first outer prongs and the at least two prongs of the radially flat portion of the first support ring are equidistant from the central longitudinal axis.
In at least one example, the second support ring further has a radially flat portion defined by at least two prongs that extend in opposite longitudinal directions, the at least two prongs of the radially flat portion of the second support ring being equidistant from the central longitudinal axis.
In at least one example, the radially flat portion of the first support ring has a circumferential position aligned with a circumferential position of the radially flat portion of the second support ring.
In at least one example, an angle subtended partially around the central longitudinal axis by the radially flat portion of the first support ring is approximately equal to an angle subtended partially around the central longitudinal axis by the radially flat portion of the second support ring.
In at least one example, the angle subtended partially around the central longitudinal axis by the radially flat portion of the first support ring is less than one hundred and eighty degrees.
In at least one example, the first inner prongs and first outer prongs are connected together by intermediate connecting segments; and the first inner prongs, first outer prongs and intermediate connecting segments together subtend a summation angle of greater than one hundred and eighty degrees around the central longitudinal axis.
In at least one example, the first support ring comprises a first portion including the first inner prongs and first outer prongs and a second portion including the radially flat portion of the first support ring; and the first portion of the first support ring is C-shaped and subtends an angle of greater than one hundred and eighty degrees around the central longitudinal axis.
In at least one example, the second inner prongs have tips directed in the first longitudinal direction; and the second outer prongs have tips directed in the second longitudinal direction opposite the first longitudinal direction.
In at least one example, the second outer prongs have tips directed in the first longitudinal direction; and the second inner prongs have tips directed in the second longitudinal direction opposite the first longitudinal direction.
In at least one example, at least one fenestration for receiving a vessel is formed through the billowing graft.
In at least one example, a radio-opaque marker is placed around the at least one fenestration.
In at least one example, the fenestration is formed through the billowing graft at a circumferential position corresponding to a circumferential position of a radially flat portion of the first support ring and a circumferential position of a radially flat portion of the second support ring.
In at least one embodiment, a method for forming a stent assembly inlcudes: providing a first support ring having interconnected circumferentially alternating first inner prongs and first outer prongs, the first support ring having a neutral state in which the first inner prongs define a first inner diameter around a central longitudinal axis, and in which the first outer prongs define a first outer diameter around the central longitudinal axis greater than the first inner diameter; providing a mandrel having at least one portion with a diameter greater than the first outer diameter; diametrically expanding the first support ring from the neutral state and at least partially surrounding the at least one portion of the mandrel with the first outer prongs; at least partially surrounding the first outer prongs with a graft; engaging the graft with the first outer prongs; removing the first support ring and graft from the mandrel; and permitting the first support ring to diametrically contract to the neutral state such that the graft follows a waving peripheral path at least partially around the first support ring.
In at least one example, the at least one portion of the mandrel with a diameter greater than the first outer diameter is a first longitudinal portion of the mandrel having a first mandrel diameter greater than the first outer diameter. The mandrel further has a second longitudinal portion adjacent the first longitudinal portion of the mandrel. The second longitudinal portion of the mandrel has a second mandrel diameter that is less than the first mandrel diameter and greater than the first inner diameter. The method further comprises at least partially surrounding the second longitudinal portion of the mandrel with the first inner prongs.
In at least one example, the graft has an exterior side and an interior side and the graft has pockets defined along the interior side. Engaging the graft with the first outer prongs includes inserting the first outer prongs into the pockets.
In at least one embodiment, a stent assembly includes a first support ring, a second support ring, a first graft, and a second graft. The first support ring has interconnected circumferentially alternating first inner portions and first outer portions, the first inner portions defining a first inner diameter around a central longitudinal axis, and the first outer portions defining a first outer diameter around the central longitudinal axis greater than the first inner diameter.
The second support ring is spaced from the first support ring along the central longitudinal axis. The second support ring has interconnected circumferentially alternating second inner portions and second outer portions, the second inner portions defining a second inner diameter around the central longitudinal axis, and the second outer portions defining a second outer diameter around the central longitudinal axis greater than the second inner diameter. The first graft engages the first support ring and second support ring, the first graft following a waving peripheral path at least partially around each of the first support ring and second support ring. The second graft at least partially surrounds the first graft such that longitudinal tunnels are defined between first graft and second graft. The second graft may be supported by a wire skeleton or stents.
In at least one example: the first inner portions of the first support ring have circumferential positions aligned with circumferential positions of the second inner portions of the second support ring; the first outer portions of the first support ring have circumferential positions aligned with circumferential positions of the second outer portions of the second support ring; the first graft has radially depressed channels extending longitudinally at the circumferential positions of the first inner portions of the first support ring; and the longitudinal tunnels are defined between the radially depressed channels and the second graft.
In at least one example, a prosthetic device for the treatment of an anatomic organ in a patient is provided. The device includes a main body having a height and a circumference and formed from a plurality of circumferentially extending wires and configured for being received in the organ of the patient. The main body defines a portion extending along a length thereof that has a reduced hoop stress relative to the remainder of the main body when in a relaxed state. A covering extends over the main body and forms a billowing recess along the length of the frame in the main body due to the portion having reduced hoop stress.
In at least one example, the main body is formed from a wire frame having leg portions connected at respective apices and bases, wherein the wire frame forms a Z stent frame.
In at least one example, at least one pair of respective leg portions defines a structural feature of one of a height between a respective apex and base of the respective leg portions that is different from a height of the remaining apices and bases.
In at least one example, a distance between two respective apices or bases is different than the distance between the apices and bases of the remaining leg portions.
In at least one example, the portion having a reduced hoop stress comprises a portion of reduced thickness wire frame relative to the remaining wire frame of the main body.
In at least one example, the portion having a reduced hoop stress has a metal forming process applied thereto in order to form the portion having a reduced hoop stress.
In at least one example, the metal forming process is electropolishing a portion of the main body to form the portion having a reduced hoop stress.
In at least one example, the covering has a circumference that is less than that of the main body when the main body is in a relaxed state.
In at least one example, one or more stent or graft members are aligned longitudinally within the billowing recess.
In at least one example, the billowing recess is formed adjacent the portion having a reduced hoop stress.
In at least one example, the device includes an outer cover positioned outwardly of the cover, a tunnel being formed between the outer cover and the cover about the billowing recess such that a stent or graft member is received within the tunnel.
In at least one example, the main body defines two portions extending along a length thereof that have a reduced hoop stress relative to the remainder of the main body when in a relaxed state. The two billowing recesses are formed along respective lengths of the frame in the main body due to the portion having reduced hoop stress.
In at least one example, the main body is configured for engaging with a further stent or graft member at a proximal end thereof, or at a distal end thereof.
In at least one example, the cover is oversized relative to the circumference of the main body.
In at least one example, the portion having a reduced hoop stress comprises a portion made from a different material than the remainder of the main body.
In at least one example, the different material is crimped with the remainder of the main body to form a continuous wire frame.
In at least one example, a prosthetic device for the treatment of abdominal aortic aneurysms in a patient is provided. The device includes a main body formed from a plurality of circumferentially extending wires and configured for being received in the abdominal artery of the patient. At least one wire forms a Z stent frame having leg portions connected at respective apices and bases, wherein at least one pair of respective leg portions defines a structural feature of one of a height between a respective apex and base of the respective leg portions that is different from the remaining apices and bases or a distance between two respective apices or bases is different than the distance between the apices and bases of the remaining leg portions. A covering is provided and has a circumference that is less than that of the main body when the main body is in a relaxed state. The covering extends over the main body when combined and forming a billowing recess in the covering due to the structural feature of the main body.
In at least one example, a method of forming a stent is provided. The method includes determining a desired structural characteristic of at least two portions of a stent frame main body that collectively form the entirety of the frame, selecting a construction of a first portion and a construction of a second portion, and forming the stent with the first portion and the second portion. The main body defines a portion extending along a length thereof that has a reduced hoop stress relative to the remainder of the main body when in a relaxed state.
In at least one example, selecting a construction of the first portion includes electropolishing the first portion in a different manner than electropolishing the second portion.
In at least one example, selecting a construction of the first portion includes selecting a different material than a second material selected for the second portion.
In at least one example, selecting a different material includes selecting a material having a different thickness or thickness selected for the second portion.
In at least one example, selecting a construction of a first portion includes selecting a different frequency of apices for the first portion than selected for the second portion.
In at least one example, selecting a construction of a first portion includes selecting a greater height distance between respective apices than selected for the second portion.
In at least one example, selecting a construction of a first portion includes selecting one portion of a frame having a sharper bend in a respective apex than the bend in a respective apex of the second portion.
In at least one example, a prosthetic device for the treatment of an anatomic organ in a patient is provided. The device includes a main body having a height and a circumference and formed from a plurality of circumferentially extending wires and configured for being received in the organ of the patient. The main body is formed from a wire frame having leg portions connected at respective apices and bases. A covering extends over the main body, the covering being oversized to a circumference of the main body when the main body is in a relaxed state. At least a portion of top-facing apices are engaged with the cover and a portion of bottom-facing apices are not engaged with the cover such that a billowing recess is formed along a length of the frame adjacent to the bottom-facing apices not engaged with the cover.
The previous summary and the following detailed descriptions are to be read in view of the drawings, which illustrate particular exemplary embodiments and features as briefly described below. The summary and detailed descriptions, however, are not limited to only those embodiments and features explicitly illustrated.
These descriptions are presented with sufficient details to provide an understanding of one or more particular embodiments of broader inventive subject matters. These descriptions expound upon and exemplify particular features of those particular embodiments without limiting the inventive subject matters to the explicitly described embodiments and features. Considerations in view of these descriptions will likely give rise to additional and similar embodiments and features without departing from the scope of the inventive subject matters. Although the term “step” may be expressly used or implied relating to features of processes or methods, no implication is made of any particular order or sequence among such expressed or implied steps unless an order or sequence is explicitly stated.
Any dimensions expressed or implied in the drawings and these descriptions are provided for exemplary purposes. Thus, not all embodiments within the scope of the drawings and these descriptions are made according to such exemplary dimensions. The drawings are not made necessarily to scale. Thus, not all embodiments within the scope of the drawings and these descriptions are made according to the apparent scale of the drawings with regard to relative dimensions in the drawings. However, for each drawing, at least one embodiment is made according to the apparent relative scale of the drawing.
Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, caudal, cranial, etcetera, may be used throughout the specification in reference to the implants and surgical instruments described herein as well as in reference to the patient's natural anatomy. Such terms have well-understood meanings in both the study of anatomy. Use of such anatomical reference terms in the written description and claims is intended to be consistent with their well-understood meanings unless noted otherwise. For example, the term “cranial” refers to the direction that is generally toward the head of the patient, and the term “caudal” refers to the direction that is generally toward the feet of the patient.
The design and geometrical shape of the endograft stent assemblies detailed in these descriptions permit separate access to the renal arteries, thus facilitating use with many anatomical variations. These designs allow for placement of parallel covered renal stents while reducing the likelihood of an endoleak along the renal stents, and reducing the risk of kinking and compression of the renal stents.
An embodiment of a support ring 102 is shown in
For example,
With brief reference now to
Returning to
The support ring 102 further includes a radially flat portion 150, illustrated as having two commonly directed prongs 152 at the circumferential margins of the flat portion 150 and an oppositely directed central prong 154. The radially flat portion 150 is distinct from other portions of the support ring 100 in that it lies in a cylindrical surface equidistant from the central longitudinal axis 104, whereas the inner prongs 112 and outer prongs 122 lie at alternating respective near and far radial distances 118 and 128 from the axis 104 with the intermediate connecting segments 130 spanning the radial difference between the near and far radial distances 118 and 128, which measure as halves of the inner and outer diameters 110 and 120 respectively. Thus, the support ring has a first circumferential portion subtending a first angle 140 and defined by alternating radially inner and outer prongs 112 and 114 with respect to the longitudinal axis 104, and a second circumferential portion subtending a second angle 142 and defined by a radially flat portion 150 at a uniform distance from the central longitudinal axis 104, that uniform distance being the far radial distance 128. The sum of the subtended first angle 140 and the subtended second angle 142 is equal to three hundred and sixty (360) degrees. In the illustrated embodiment, the first portion is C-shaped as defined by the summation angle 140 being greater than one hundred and eighty (180) degrees.
As shown in
In the stent frame 400 of
In the stacked arrangement of support rings 102, 202 and 302 in the stent frame 400 of
The VDS assembly 500 is shown in
In particular, portions of the graft 502 overlying the circumferential positions of the exterior longitudinal channels 432 defined by the stent frame 400 are shown as billowed inward in
In use in which, for example, blood flows along central fluid flow channel 504 toward the lower longitudinal end 522 of the VDS assembly 500, the graft 502 is expected to billow outwardly to contact arterial or aortic tissue along the exterior of the graft 502. The side stents 532a and 532b are supported and localized within the longitudinal channels 432 between the major cover graft 502 and the tissue. This facilitates blood flow within the longitudinal fluid flow channels 506a and 506b defined within the side stents 532a and 532b. The billowing properties of the graft will create a complete seal along the side stents 532a and 532b. As such, these descriptions refer to the VDS assembly 500 as having a billowing graft, referring to the billowing aspect of the major cover graft 502.
Assembly of the billowing graft VDS assembly 500, and other billowing graft VDS assemblies within the scope of these descriptions, can be understood in view of
Thus, the stent frame 400 and each support ring 102, 202 and 302 is diametrically expanded onto the mandrel 700 in
The graft 502 generally maintains the support rings 102, 202 and 302 as approximately concentric with the longitudinal axis and spaced along the longitudinal axis as shown in
As shown in
Additionally, the graft 502 may be sewn to the stent frame 400 or attached in any other appropriate manner such as glue, suturing, lamination, or a mechanical fastener such as a clip. Thus, various attachment steps may be carried out while the, stent frame 400 and graft 502 are engaged with the mandrel 700.
These descriptions refer here to materials and making of the support ring 102, noting that the support rings 202 and 302 can be similarly made. In at least one embodiment, the support ring 102 is made of a memory shape wire, such as nitinol. Other biocompatible materials may be used. The memory shape wire is formed and heat treated in a fashion to create longitudinal and radial support. The ring 102 is formed such that the outer prongs 122 exert an outward radial force. In the illustrative embodiment, the outer prongs 122 exert a higher radial force than the inner prongs 112.
The variation in radial force may be accomplished in a variety ways. For example, the outer prongs 122 may have a different Austenite finish temperature (“Af”) than inner prongs 112. To do so, the inner prongs 112 would be insulated/masked during a high temperature and time heat set-processing. The entire ring 102 would be heated to a certain temperature before the inner prongs 112 are masked or insulated. The outer prongs 122 would then be exposed to a more aggressive heat-set process to achieve a high radial force, while the masking of the inner prongs 112 would result in a lower radial force. In at least one embodiment, the high radial force area would have an Af<30 degrees Celsius and the lower radial force area would have an Af somewhere in the range of 35-39 degrees Celsius.
Another method of achieving the variation in radial force may be to electropolish the entire ring 102 up to a certain point. The outer prongs 122 may then be masked before further electropolishing of the inner prongs 112, thereby making the wire thinner in diameter in that section and resulting in a lower radial force. It should be appreciated that a combination of these two approaches may also be used. Additionally, in other embodiments, the radial force exerted by the outer prongs 122 may vary such that the force exerted by some of the outer prongs 122 is less than the force exerted by the inner prongs 112. Similarly, the radial force exerted by the outer prongs 122 may vary such that the force exerted by some of the inner prongs 112 is greater the force exerted by the outer prongs 122.
Whether made by these described materials and methods or others, the stent frame 400 is somewhat flexible, for example in order to stretch onto the mandrel 700, and is resilient so as to return to its neutral dimensions to facilitate the billowing aspect of the major cover graft 502. The flexible and resilient properties of the stent frame 400 also facilitate that the VDS assembly 500 conforms to shapes and dimensions of surrounding biological tissue in use while the side stents 532a and 532b are supported and localized within the longitudinal channels 434 between the cover graft 502 and the tissue.
A stent frame according to these descriptions as flexible and resilient so as to return to neutral dimensions refers both to diametrically contracting to neutral dimensions after being diametrically expanded and diametrically expanding to neutral dimensions after being diametrically compressed. For example, upon removal from the mandrel 700, the stent frame 400, the stent frame diametrically contracts to neutral dimensions. Conversely, if diametrically compressed, the stent frame 400 is resiliently self-biased toward neutral dimensions and bears outward force upon any outer structure or tissue that constrains the stent frame 400 to less than its neutral diameter. This feature facilitates that a VDS stent assembly including such a frame conforms to anatomical dimensions to assure against endoleaks.
In at least one example, in which a first installed stent frame requires further support, a second self-expanding stent frame is inserted into the first self-expanding stent frame. For example, if anatomical dimension change over time after first installment of a frame-supported stent assembly, a second stent frame can be subsequently installed within the first stent frame. The second self-expanding stent frame then bears gentle outward force upon the interior of the first stent frame, further supporting the stent assembly, increasing the diameter of the first stent and urging it to conform to the new anatomical dimensions.
In the illustrated embodiment, the support ring 102 has eight (8) radial depressions 132 as shown in
Support rings 102, 202 and 302 are illustrated as having the same inner diameters such that the stent frame 400 has the same inner diameter 110 defined by the inner prongs of each support ring. Similarly, support rings 102, 202 and 302 are illustrated as having the same outer diameters such that the stent frame 400 has the same outer diameter 120 defined by the outer prongs of each support ring. In other embodiments, the dimensions of support rings along the length of a stent frame can vary, for example to suit the various anatomies of different patients. In at least one embodiment, the inner diameter 110 of the stent frame 400 is approximately thirty (30) millimeters and the outer diameter 120 is approximately thirty eight (38) millimeters. While the stent frame 400 is illustrated to have three support rings as shown in
Referring now to
The major cover graft 502 is used on the external surface of the stent frame 400. The graft 502 may be formed as covered Z stents, mesh wire, braided stents and other constructions of stent like material and biologically inert coverings (e.g. PTFE, polyester, ePTFE etc.) impermeable to blood and serum. The major cover graft 502 covers the stent frame 400 partially or completely along its length or circumference. Once the graft 502 is applied to the stent frame 400, the graft 502 defines walls of the exterior longitudinal channels 432 along which different branches of the aorta may be accessed and cannulated. The side stents 532a and 532b and other stents and grafts can be placed in fluid communication with central fluid flow channel 504. Thus, connections can be made through the major cover graft 502 to aortic branches such as coronary arteries, aortic arch branches, visceral branches and hypogastric arteries.
For example, in
While the stent frame 400 is illustrated to have three support rings as shown in
For example, a stent frame 800 according to at least one embodiment is shown in
The first frustoconical support ring 810 is formed as a Z-stent having a first end 812 with a diameter greater than that of a second end 814. The first end 812 is defined by turning points of the Z-stent extending outward from the longitudinal axis 802. The second end 814 is defined by turning points of the Z-stent extending inward from the longitudinal axis 802.
The single diameter support ring 820 is formed as a Z-stent in which turning points are equidistant from the longitudinal axis 802. The support ring 102 and the support ring 302 are detailed in the preceding descriptions with reference to
The second frustoconical support ring 830 is formed as a Z-stent having a first end 832 with a diameter greater than that of a second end 834. The first end 832 is defined by turning points of the Z-stent extending outward from the longitudinal axis 802. The second end 834 is defined by turning points of the Z-stent extending inward from the longitudinal axis 802.
The single diameter support rings 820, 840, and 850 are formed as Z-stents in which respective turning points are equidistant from the longitudinal axis 802, defining a single respective diameter for each ring. The second and third single-diameter support rings 840 and 850 are illustrated having the same diameter in the stent frame 800. The first single diameter support ring 820 is illustrated as having greater diameter than the second and third single-diameter support rings 840 and 850, which are downstream of the diameter-reducing second frustoconical support ring 830 relative to the first single diameter support ring 820.
Similar to the way the stent frame 400 of
To attach the upstream end of the stent frame to host tissue, stabilizing elements may be connected to the first frustoconical support ring 810 as shown in
Each stabilizing element 860 also includes a limb 864 (
Each stabilizing element 860 may be formed separately from stainless steel or other metal. It can be laser cut in whole together with the support ring 810. The stabilizing elements 860 may be individually wrapped around a prong 816. The shape of the element 860 as depicted allows for one end of the wire to “hook” into the aortic wall, thereby stabilizing the device and preventing migration of the endograft. The caudal end of the limb 864 will have an eccentrically directed angle and this portion of the wire will be located on the inside aspect of the graft coverage, in this embodiment the PTFE. By positioning the caudal end of the limb 864 at an angle in between each pair of prongs 816, the endograft coverage will be pushed externally against the aortic wall to create additional points of contacts and seal. In addition, if the limbs 864 are captured towards the center of the graft with the delivery system, they can restrain the top stent and make the device easier to control.
In
In
In
In
The fenestration support ring 1120 may also serve as a radio-opaque marker during the placement procedure of the stent assembly 1100. In such use, the fenestration support ring 1120 serves as “point zero” for the positioning and deployment of the stent assembly 1100, or any stent assembly in which the fenestration support ring 1120 is included. Advantageously, the fenestration support ring 1120 for such use can be constructed of or with materials visible under X-ray or other medical imaging techniques.
A particular exemplary construction for the fenestration support ring 1120 is represented in
The stent frame 1200 can be constructed of a metal alloy, including a memory shape wire such as nitinol. Other biocompatible materials may be used. In at least one example, the memory shape wire is cut and heat treated in a fashion to create longitudinal and radial support. The stent frame 1200 includes circumferential wires 1202 shaped to define circumferential waves that are aligned longitudinally to define longitudinal channels. A radial variation is defined between the crests (radial maxima) and nadirs (radial minima) of the circumferential waves. In at least one example, the radial variation is approximately three (3) millimeters. In other examples, the radial variation may be in the range of two to four (2-4) millimeters. The circumferential distance between the crests can be, for example, in the range of three to fifteen (3-15) millimeters. Like the stent frame 400 that includes a radially flat portion 450 (
The stent frame 1200 includes longitudinal wires 1204 that extend between the circumferential wires. Each circumferential wire 1202 is spaced, for example at 5-20 mm, from the next and has a wave shape to define the longitudinal channels. The circumferential positions of the longitudinal wires 1204 alternate in a staggered fashion.
The endograft stent assembly 1300 includes a fenestration support ring 1320, which, in the illustrative embodiment, is an 8mm nitinol ring. The fenestration support ring 1320 is positioned or created within the stent frame 1200 with its center point at approximately thirty four (34) millimeters below the top edge 1302 of the stent 1300. The fenestration support ring 1320 in at least one use receives the visceral or SMA stent placed during the placement procedure. The fenestration support ring 1320 also serves as “point zero” for the positioning and deployment of the endograft stent assembly 1300. A second ring (not shown) may be positioned cranial of the SMA fenestration support ring 1320, with its center approximately fifteen (15) millimeters cranial to the fenestration support ring 1320. The center of the second ring may be at 12:30 clock position relative to the SMA fenestration support ring 1320, and the diameter of the second ring may measure between eight and ten (8-10) millimeters.
The stent frame 1200 may be formed as one unit. In at least one embodiment the stent frame 1200 approximately one hundred (100) millimeters in longitudinal length. The proximal aspect of the stent frame 1200 is wavy tubular extending thirty four (34) millimeters proximal to the center point of the visceral or SMA fenestration support ring 1320. The distal aspect extends fourteen (14) millimeters below the center point of the SMA fenestration support ring. At this level, the stent frame 1200 includes a distal extension 1210 that funnels to eighteen (18) millimeters or more in diameter over a distance of ten to twenty (10-20) millimeters. This distal extension 1210 is approximately fifty to sixty (50-60) millimeters long, with at least the most distal forty (40) millimeters measuring at least eighteen (18) millimeters in diameter. In at least one embodiment, the most anterior portion of the proximal part of this stent frame 1200 is curved flat and does not have any waves or channels.
As shown in
In the illustrated embodiment of
In
A graft tube 1610 reinforced with Z stents is shown in
By placing the iliac bifurcation at a maximum cranial location possible within the iliac limb system as illustrated and described here, there is room to move the second iliac limb stent 1608 up or down and adjust the desired length remaining for engagement with an iliac artery. The two flow channels for the two iliac limb stents 1604 and 1608 are separated by the septum 1608 throughout the upstream dual channel part of the tubular stent. The septum 1602 prevents the upstream cranial end of the second iliac limb stent 1608, as the position of the stent 1608 is adjusted, from obstructing the flow entering the first iliac limb stent 1604 on the other side of the septum 1602. This permits a range of human anatomy dimensions to be served by one set of components (
To achieve the installation shown In
Lower portion of side stents 523a and 523b are then engaged with the renal arteries as shown in
Subsequent to installation of the stent assembly 1000, the first iliac limb stent 1604 can be positioned in different locations by the telescoping engagement of the upstream end of the dual channel tubular stent with the downstream end of the stent assembly 1000. The adjustable telescoping engagement of the dual chamber stent with the stent assembly 1000 defines a functional length adjustment for the first iliac limb stent 1604 relative to the engage first iliac limb artery. The position of the dual chamber tubular stent is selected to engage the first iliac limb stent 1604 with the first iliac limb artery. Once the engagements of
Thus, an endovascular device (endograft) for treatment of complex abdominal aneurysms involving the kidney vessels is provided. The device can go above the kidney vessels, while blood flows to the kidneys and the gut vessels are preserved. In the parallel endograft technique in which stents 523a and 523b are installed alongside the aortic endograft, the aortic endograft does not crush the kidney stents or create gutters that may otherwise cause leaks of blood alongside the grafts. These are advantages of these variable depression stent (VDS) and billowing graft assemblies.
As illustrated in
As illustrated, the main body 2012 is formed from a wire frame 2014 having leg portions 2026 connected at respective apices 2028 and bases 2030, wherein the wire frame forms a z-stent frame.
The one or more portions 2016 having a reduced hoop stress relative to a remainder of the main body when in a relaxed state may be accomplished in a variety of manners. For example, as illustrated in
In one or more embodiments, a distance D1 between two respective apices 2028 or bases 2030 is different than the distance D2 between the apices 2028 and bases 2030 of the remaining leg portions as illustrated in
In an embodiment illustrated in
Similarly, in the embodiments illustrated in
As illustrated in
The stent 2110 in a pressurize state is shown in
The devices disclosed in
Disclosed herein are one or more methods and one or more stents made according to the one or more methods in which the stents exhibit improved structural characteristics over conventional stents or other stents used in manufacturing endografts. For each method step listed, a corresponding stent structure may be made according to the method described. As disclosed herein, one or more methods of forming a stent may include determining a desired structural characteristic of at least two portions of a stent frame that collectively form the entirety of the frame or a circumferential row of a row of the frame. The one or more characteristic may be any desired structural characteristic, such as, for example, rigidity, flexibility, compressibility, radial strength, axial strength, smoothness of finish, and the like. The method may also include selecting a first material for a first portion and a second material for a second portion. Alternatively, similar materials may be selected but different finishing processes may be used to reach a desired structural characteristic. The method may also include forming the stent with the first and second material. As used herein, material may include a type of material, a finishing process applied to a material, a size, dimension, or similar of a material, or a shape of a material.
According to one or more embodiments, selecting a first material includes electropolishing a first material in a different manner that electropolishing a second material. This may advantageously provide for a different thickness of frame material for prolonged electropolishing, or may provide for a different smoothness or texture of finish. Such a selection will impact the radial and axial strength of the stent, as well as the weight and finish characteristics. A representative example of one form of electropolishing compared to an above-standard form of electropolishing is illustrated in
According to one or more embodiments, selecting a first material may include selecting one portion of the frame have a different material than a second material. In this manner, consecutive rows in a stent could be made from different materials having different structural characteristics. Alternatively, the first portion of material could have a different thickness or thickness than the second material. By attaching the stent wireforms/frame portions of different thickness, the stents with thicker wires will provide stability and seal against the aortic wall, and the stents with thinner wires will exert less radial force against the aortic wall. This allows support for the parallel renal endografts or any longitudinally placed stent outside of the main body stent without crushing them.
Alternatively, a given row of frame material could have one portion that has a different thickness than a second portion due to electropolishing one portion more or from joining materials of different thickness.
According to one or more embodiments, the method may include selecting one portion of a frame having a different frequency of apices than a second material.
According to one or more embodiments, the first and second material or portions may be engaged by any appropriate mechanism, including welding, crimping, soldering, and the like.
Particular embodiments and features have been described with reference to the drawings. It is to be understood that these descriptions are not limited to any single embodiment or any particular set of features, and that similar embodiments and features may arise or modifications and additions may be made without departing from the scope of these descriptions and the spirit of the appended claims.
Claims
1. A prosthetic device for the treatment of an anatomic organ in a patient, the device comprising:
- a main body having a height and a circumference and formed from a plurality of circumferentially extending wires and configured for being received in the organ of the patient, wherein the main body defines a portion extending along a length thereof that has a reduced hoop stress relative to a remainder of the main body when in a relaxed state; and
- a covering extending over the main body and forming a billowing recess along the length thereof due to the portion having reduced hoop stress.
2. The prosthetic device of claim 1, wherein the main body is formed from a wire frame having leg portions connected at respective apices and bases, wherein the wire frame forms a Z stent frame.
3. The prosthetic device of claim 2, wherein at least one pair of respective leg portions defines a structural feature of one of a height between a respective apex and base of the respective leg portions that is different from a height of the remaining apices and bases.
4. The prosthetic device of claim 2, wherein a distance between two respective apices or bases is different than the distance between the apices and bases of the remaining leg portions.
5. The prosthetic device of claim 1, wherein the portion having a reduced hoop stress comprises a portion of reduced thickness wire frame relative to the remaining wire frame of the main body.
6. The prosthetic device of claim 1, wherein the portion having a reduced hoop stress has a metal forming process applied thereto in order to form the portion having a reduced hoop stress.
7. The prosthetic device of claim 6 wherein the metal forming process is electropolishing a portion of the main body to form the portion having a reduced hoop stress.
8. The prosthetic device of claim 1, wherein the covering has a circumference that is larger than that of the main body when the main body is in a relaxed state.
9. The prosthetic device of claim 1, wherein one or more stent or graft members are aligned longitudinally within the billowing recess.
10. The prosthetic device of claim 1, wherein the billowing recess is formed adjacent the portion having a reduced hoop stress.
11. The prosthetic device of claim 1, wherein the main body defines two portions extending along a length thereof that have a reduced hoop stress relative to the remainder of the main body when in a relaxed state, and further wherein two billowing recesses are formed along respective lengths of the main body due to the portion having reduced hoop stress.
12. The prosthetic device of claim 1, wherein the main body is configured for engaging with a further stent or graft member at a proximal end thereof.
13. The prosthetic device of claim 1, wherein the main body is configured for engaging with a further stent or graft member at a distal end thereof.
14. The prosthetic device of claim 1, wherein the cover is oversized relative to the circumference of the main body.
15. The prosthetic device of claim 1, wherein the portion having a reduced hoop stress comprises a portion made from a different material than the remainder of the main body.
16. The prosthetic device of claim 15, wherein the different material is crimped with the remainder of the main body to form a continuous wire frame.
17. A method of forming a stent comprising:
- determining a desired structural characteristic of at least two portions of a stent frame main body that collectively form the entirety of the frame;
- selecting a construction of a first portion and a construction of a second portion; and
- forming the stent with the first portion and the second portion,
- wherein the main body defines a portion extending along a length thereof that has a reduced hoop stress relative to the remainder of the main body when in a relaxed state.
18. The method of claim 17, wherein selecting a construction of the first portion includes electropolishing the first portion in a different manner than electropolishing the second portion.
19. The method of claim 17, wherein selecting a construction of the first portion includes selecting a different material than a second material selected for the second portion.
20. The method of claim 18, wherein selecting a different material includes selecting a material having a different thickness or thickness selected for the second portion.
21. The method of claim 17, wherein selecting a construction of a first portion includes selecting a different frequency of apices for the first portion than selected for the second portion.
22. The method of claim 17, wherein selecting a construction of a first portion includes selecting a greater height distance between respective apices than selected for the second portion.
23. The method of claim 17, wherein selecting a construction of a first portion includes selecting one portion of a frame having a sharper bend in a respective apex than the bend in a respective apex of the second portion.
Type: Application
Filed: Jul 28, 2016
Publication Date: Dec 15, 2016
Inventor: Ali Shahriari (Boca Raton, FL)
Application Number: 15/221,724