Stent and stent graft with high density support stent

Abstract

An endovascular prosthesis includes a stent having a plurality of radially expandable circumferential rings arranged along a longitudinal axis with a circumferential gap between the plurality of radially expandable circumferential rings. At least some of the expandable rings include cells comprising struts joined by a crown, and at least some of the cells or a midpoint in the struts of the cells has a radius R measured from the longitudinal axis of the stent, and a midpoint in a gap between circumferentially adjacent cells has a radius r measured from the longitudinal axis of the stent. After the stent radially expands up to 200% from the delivery radius, the outer surface of the stent maintains a roundness of at least 97% measured at r / R * 100, and the stent is configured to radially expand in situ from the delivery configuration to the deployed configuration in the target blood vessel.

Description

Cross Reference to Related Applications

[0001] This PCT application claims the benefit of U.S. Provisional Application No. 63 / 586,268 (Attorney Docket No. 32016-733.102), filed September 28, 2023, and U.S. Provisional Application No. 63 / 501,454 (Attorney Docket No. 32016-733.101), filed May 11, 2023, the entire contents of which are incorporated herein by reference. The entire contents of which are incorporated herein by reference.

[0002] This PCT application will also be a continuation-in-part of U.S. Patent Application No. 18 / 482,711 (Attorney Docket No. 32016-730.301), filed October 6, 2023, which claims priority to PCT / US2023 / 16449, filed March 27, 2023, which claims the benefit of U.S. Provisional Application No. 63 / 324540 (Attorney Docket No. 32016-730.101), filed March 28, 2022, U.S. Provisional Application No. 63 / 327,326 (Attorney Docket No. 32016-730.102), filed April 4, 2022, and U.S. Provisional Application No. 63 / 487,773 (Attorney Docket No. 32016-730.103), filed March 1, 2023, the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] 1. Field of the invention The present invention relates generally to medical devices and methods, and more particularly, to stents and stent grafts having a stent pattern configured for deployment on aneurysms in the cerebral vasculature, the cardiac vasculature, and the peripheral vasculature of a patient.

[0004] Millions of people worldwide suffer from stroke each year. Strokes are generally classified into two categories: ischemic stroke and hemorrhagic stroke. Ischemic stroke is caused by a blood clot or other obstruction cutting off blood supply to the brain. This is the most common type of stroke. Hemorrhagic stroke is caused by bleeding into or around the brain resulting from a ruptured brain artery, often referred to as a “brain aneurysm.” The present invention is particularly directed to the treatment of brain aneurysms, but can also be used to treat aortic aneurysms and other vascular aneurysms and other vascular diseases that can benefit from the placement of a stent and / or stent graft.

[0005] Cerebral aneurysms can be treated by both surgical techniques and less invasive catheter-based techniques. Surgical techniques require opening the patient's skull to create a craniotomy through which a surgeon can insert instruments to directly operate on the patient's brain. In some cases, the brain must be retracted to expose the defective blood vessel. After access is established, the aneurysm can be treated in a variety of ways. For example, the aneurysm can be closed by placing a clip over the opening, commonly referred to as the "neck," to stop arterial blood from the blood vessel from entering the aneurysm. While this surgical intervention is very effective, it is invasive and older patients and patients with comorbidities are often excluded.

[0006] Less invasive procedures have been developed and generally rely on the delivery of stents, stent grafts, and / or embolic devices or other vascular occlusive devices or materials into the target aneurysm. Stents and stent grafts are intended to bypass or drain blood flow, preventing entry into the aneurysm, while vascular occlusive devices or materials can be used to promote hemostasis or to completely fill the aneurysmal cavity. Often, a coil or other vascular occlusive device can be delivered through the wall of a previously placed stent or graft, particularly when treating wide-necked aneurysms.

[0007] Cerebral stents and stent grafts generally include self-expanding or balloon-expandable stents to keep the device open after implantation. Such stents can be covered with a sleeve of polymer or other material to form a stent graft. Stents and stent grafts are generally delivered to the target aneurysm by a delivery "microcatheter" delivery catheter.

[0008] To make these stents and stent grafts small enough to pass through microcatheters configured to access the distal cerebral vasculature, the metal "density" of the stents is generally reduced to reduce the size and increase flexibility. However, when expanding low-density stents, the stent structure bridging the aneurysm neck can become open and very porous, often failing to provide sufficient isolation to "seal off" the aneurysm, i.e., the blood in the aneurysm cannot clot. In such cases, it is often necessary to use the stent in conjunction with a vascular occlusive device, such as a coil discussed above, in order to occlude the aneurysm.

[0009] For these reasons, it would be desirable to provide stents and stent grafts with enhanced flexibility while maintaining sufficient density when expanded in the cerebral vasculature or other vasculature to effectively treat aneurysms. The stents and stent grafts should have very small diameters and be suitable for both balloon expansion and self-expansion. Further, it would be desirable to provide catheters and systems to deliver such stents and stent grafts to distal regions of the cerebral vasculature or other vasculature. Different aspects of the present invention will meet at least some of these objectives.

[0010] 2. BACKGROUNDBlood flow diversion stents and similar devices having various stent patterns are described in WO2019 / 059949; US2010 / 0204779; US8915954; US7942920; US7918884; US2013 / 0123901; US2011 / 0034991; US10959865; US8764814; US8323760; US8206428; US7625401; US7291165; and US7247166. SUMMARY

[0011] The present invention provides an improved endovascular prosthesis having a support stent that optimizes flexibility during delivery and wall coverage after deployment. The stent has a particular pattern that is highly flexible when the stent is radially collapsed in its delivery configuration and maintains a high wall density after being radially expanded to its delivery configuration. While typically combined with a covering membrane to form a stent graft, the stent of the present invention can also have an "open" configuration when used, i.e., without a membrane or other covering when deployed. The endovascular prosthesis of the present invention will also most often be configured to balloon expand, but in other cases will be configured to self-expand.

[0012] In a first aspect of the present invention, the endovascular prosthesis will include a radially expandable stent including a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps between the plurality of radially expandable circumferential rings. At least some of the radially expandable rings include a cell including struts joined by a crown, and a membrane is optionally secured to the expandable stent (typically molded or laminated with the stent). Alternatively, the stent can be without a membrane or any other covering, e.g., configured as a blood flow diversion stent for treating a cerebral aneurysm.

[0013] The stent cells of the present invention will typically have a radius R measured from the longitudinal axis of the stent to the midpoint of the struts on the outer surface of the cell, while the midpoint of the gap between circumferentially adjacent cells will have a radius r measured from the longitudinal axis of the stent, where R>r. The outer surface of the stent (whether a membrane or a bare metal stent) maintains a circularity of at least 97% measured as r / Rx 100 after the stent is radially expanded from a delivery radius by up to 200%, typically at least 97% measured as r / Rx 100 after the expandable support structure is radially expanded from a delivery radius by up to 100%, more typically at least 97% measured as r / Rx 100 after the expandable support structure is radially expanded from a delivery radius by up to 50%, frequently at least 98% measured as r / Rx 100 after the expandable support structure is radially expanded from a delivery radius, and preferably at least 98.5% measured as r / Rx 100 after the expandable support structure is radially expanded from a delivery radius.

[0014] In a second aspect of the application, a stent of an endovascular prosthesis comprises an expandable coil comprising successive turns of a helix disposed along a longitudinal axis. The turns of the expandable coil have gaps between them and comprise undulations and struts that allow the turns to expand radially. The successive turns are tilted at an acute pitch angle with respect to the longitudinal axis, the acute pitch angle ranging from 85° to 89.9°, preferably from 86° to 89°, and more preferably from 86° to 88°. A membrane is optionally secured to the expandable coil (typically molded or laminated with the coil) and the expandable coil is configured to expand radially from a delivery configuration to a deployed configuration having an axial blood flow passage therethrough. A rotatable impeller is configured to be disposed in the axial blood flow passage therethrough.

[0015] In a third aspect of the application, an endovascular prosthesis comprises a stent comprising a plurality of radially expandable circumferential rings arranged along a longitudinal axis, with circumferential gaps between the plurality of radially expandable circumferential rings, wherein at least some of the radially expandable circumferential rings comprise a serpentine or zigzag structure comprising struts joined by crowns. A plurality of support elements each have a base end and a free end, wherein the base end of the support elements are attached to an inner side of the crowns and the free ends are disposed between adjacent struts attached to the crowns.

[0016] In a preferred case, the free ends of the support elements are recessed within or flush with the circumferential rings and do not protrude into the circumferential gaps prior to radial expansion of the distal tips. Alternatively, at least some of the free ends of the support elements can protrude into the circumferential gaps after expansion of the distal tips, and in both cases the support elements are generally configured to lie within a cylindrical envelope defined by the stent.

[0017] In a fourth aspect, the application provides an endovascular prosthesis delivery system comprising an elongated catheter body having a distal end, a proximal end, and an inflatable balloon at the distal end. A balloon-expandable endovascular prosthesis having any of the designs described herein can be mounted on the inflatable balloon.

[0018] In a fifth aspect, the application provides an endovascular prosthesis delivery system comprising an elongated sheath having a distal end and a proximal end. A self-expanding endovascular prosthesis having any of the designs described herein can be retracted within a lumen at the distal end of the elongated sheath.

[0019] In a sixth aspect, the present application provides methods of delivering an endovascular prosthesis into a vasculature of a patient. An endovascular prosthesis of any of the preceding claims can be coupled to a distal end of a delivery device in its radially collapsed configuration. The distal end of the delivery device is positioned within the vasculature of the patient at a target aneurysm, and the endovascular prosthesis is deployed to span the target aneurysm. In some cases, the endovascular prosthesis is deployed using an inflatable balloon. In other cases, the endovascular prosthesis is released from radial constraint within a delivery sheath to self-expand at the target aneurysm.

[0020] In particular cases, the endovascular prostheses and methods of the present application can include a non-porous membrane.

[0021] In particular cases, the endovascular prostheses and methods of the present application can include a porous membrane.

[0022] In particular cases, the endovascular prostheses and methods of the present application can include a perforated membrane.

[0023] In particular cases, the endovascular prostheses and methods of the present application can include a membrane that extends completely over the stent or coil.

[0024] In particular cases, the endovascular prostheses and methods of the present application can include a membrane that extends only over a central portion of the stent or coil, leaving terminal regions uncovered.

[0025] In particular cases, the endovascular prostheses and methods of the present application can include a membrane that carries a pharmaceutically active agent.

[0026] In particular cases, the pharmaceutically active agent can include one or more anti-platelet agents, anti-fibrotic agents, anti-inflammatory agents, anti-proliferative agents, anti-glaucoma agents, immunosuppressive agents, anti-diabetic agents, anti-viral agents, anti-angiogenic agents, anti-VEGF agents, serine protease inhibitors, complement activation inhibitors, antihistamines, or combinations thereof.

[0027] In particular cases, the pharmaceutically active agent can include a Factor Xa inhibitor, a Factor IIa inhibitor, or a combination of a Factor Xa inhibitor and a Factor IIa inhibitor, optionally in combination with one or more additional agents (e.g., as listed above).

[0028] In a first aspect, the present invention provides an aspiration catheter (such as but not limited to a cerebral aspiration catheter, a coronal artery aspiration catheter, an arterial aspiration catheter, or a venous aspiration catheter) comprising a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending between the proximal end and the distal end. The aspiration catheter has an expandable distal tip having a central passage (or channel) that is connected to the aspiration lumen of the tubular catheter body. An expandable support structure is attached to, embedded within, or otherwise coupled to the expandable distal tip of the tubular catheter body. In some cases, the expandable support structure can be attached to an outer surface or an inner surface of an expandable membrane, but more commonly it will be embedded or laminated within an expandable membrane, such as a polymer membrane comprising one, two, three, or more layers and composed of one, two, three, or more polymeric materials or other materials.

[0029] The phrase "distal tip" as used herein and in the claims refers to a length or region at the distal end of the aspiration catheter. The distal tip will typically be constructed differently from the proximal region or shaft of the aspiration catheter. In particular, the distal tip will typically be constructed to expand from a small diameter or from a low profile configuration or from a delivery configuration or from a delivery configuration to a large diameter or larger configuration or expanded configuration or deployed configuration, or an enhanced retrieval configuration, which has greater clot aspiration or clot retrieval force when a vacuum is applied at the proximal end of the aspiration catheter and the distal tip is engaged with a clot, where the expanded (or deployed) configuration of the distal tip remains substantially the same (or remains substantially expanded or deployed) when the vacuum is applied, thereby resisting collapse, typically it is balloon expandable but sometimes self-expanding. In contrast, the proximal region or shaft typically has a fixed diameter along its length. The fixed diameter of the proximal region or shaft can be constant or can vary along its length. The distal tip in the delivery configuration can be a first clot retrieval configuration, and the distal tip in the expanded configuration can be a second clot retrieval configuration, where the second clot retrieval configuration has greater retrieval force than the first clot retrieval configuration. In other examples, the expanded configuration can be a clot retrieval configuration, or can be a preferred clot retrieval configuration, as it typically has enhanced clot retrieval force. The distal tip typically terminates at the distal end of the aspiration catheter.

[0030] The support structure is typically in the form of a stent and is configured to allow the expandable membrane to radially expand, typically by applying a radially outward expansion of a balloon or other expandable member placed within the support structure, and, particularly when the distal tip is engaged with (or clogged or blocked by) a clot and a vacuum is applied through the aspiration lumen, the support structure is configured to enhance the collapse resistance of the expandable membrane, i.e., to resist or prevent the expandable membrane from collapsing or to prevent the lumen configuration of the expandable membrane from decreasing after the expandable support stent is expanded to an expanded configuration, or to substantially maintain the expanded lumen configuration of the expandable membrane when a vacuum is applied at the proximal end of the aspiration lumen while engaged with a clot.

[0031] The support structure typically includes a plurality of radially expandable rings arranged along the longitudinal axis with gaps between the plurality of radially expandable rings (forming circumferential gaps between adjacent rings). The radially expandable rings will typically include circular, square, rectangular, elliptical, spiral, or other annular ring elements configured to inelastically elongate (along their curved length) to allow the distal tip to expand circumferentially. Exemplary ring elements can be formed as serpentine, zigzag, box-shaped (square or rectangular), diamond, or other patterns including curved sections that inelastically open in response to a radially outward force provided by a balloon or other expandable deployment member or structure. Exemplary rings can be open cell designs, closed cell designs, combinations of open and closed cell designs, or others. Exemplary ring designs can be formed from a tubular body, a curved wire, a patterned sheet rolled into a tubular shape, or by printing or other.

[0032] Exemplary open cell support structures can include serpentine and zigzag ring patterns including struts linked by crowns, where the crowns include "bends" that non-elastically open to allow radial and circumferential ring expansion. While each circular or circumferential ring can have an even or odd number of crowns and struts, each side or face of the ring can have an even or odd number of crowns. Each ring, including terminal rings, preferably has at least 14, 17, 12, 26, 30, 32, 34, 38, 40, 42, 60, 80, 100, 120, 140, 161, 160, 180, 200, or more crowns as counted on two sides / faces of the ring. For example, when a ring is said to have 14 crowns, the total number of crowns is 14 when counting both sides or faces of the ring. Higher crown numbers of 60, 80, 100, 120, 1400, 1600, 180, 200, and 400 or more are preferred when the support structure does not include additional support elements, or when the support structure units within a ring, or the units within a plurality of rings, or the units within each ring include several support elements or include at least some but not all of the support elements, as described below. Smaller crown numbers such as 14, 22, 26, 30, 32, 34, 38, 40, 42, 48, 60, and 80 are generally sufficient when the support structure includes at least some or a large number of support elements per ring, per at least some adjacent rings, or per ring along the length of the expandable support structure. The crown number per ring, or per at least some adjacent rings, or per ring along the length of the expandable support structure is configured to allow the expandable support structure to expand to an expanded configuration.

[0033] It has been found that (1) a greater number of crowns or other bends without support elements and (2) a lower number of crowns in combination with support elements will enhance the roundness of the loops in the distal tip in both the delivery configuration and the expanded configuration, maximizing the available aspiration lumen area. The phrase "number of crowns or bends per loop" refers to the total number of crowns or bends counted in a single 360° rotation around each loop. While the "number of crowns or bends per loop" will typically be constant for each loop in an open cell support structure, in some cases the number can vary from loop to loop. The enhanced roundness of the distal tip (expandable support structure and expandable membrane) in the expanded configuration can increase the aspiration lumen area, increase the vacuum force, resist lumen collapse and deformation when a vacuum is applied at the proximal end of the aspiration lumen and the distal tip is engaged with a clot (or when the distal tip is clogged or blocked by a clot or other material). Furthermore, the enhanced roundness resists deformation and / or kinking of the expandable distal tip in the delivery configuration as the catheter is advanced into the vasculature. The maximized roundness of the loops can be further enhanced by having a small cell period and / or a small cell amplitude. In a preferred example, the expandable support structure includes a plurality of loops, where at least some of the loops (preferably substantially all of the loops) are configured to have a large number of crowns, a small cell period, and a small cell amplitude to have enhanced circumferential roundness.

[0034] In a preferred loop pattern that includes struts connected by crowns (e.g., such as a serpentine pattern), the ratio of (1) the number of bends (e.g., crowns) per loop to (2) the circumference (perimeter) of the loop measured in millimeters (mm) is typically at least 3 crowns or bends per mm of circumferential length, often at least 4 crowns or bends per mm of circumferential length, typically in the range of 3 to 18 crowns or bends per mm of circumferential length, typically 4 to 15 crowns or bends per mm of circumferential length, and most preferably in the range of 4 to 12 crowns or bends per mm of circumferential length. An increased number of crowns or bends in each loop (or in most loops in some cases or in multiple loops in other cases) or a high ratio of crowns or bends per circumferential length improves the roundness of the distal tip (including the expandable support structure and the expandable membrane) in the expanded configuration, increases the aspiration lumen area or maximizes the lumen area, enhances the vacuum force, and resists collapse of the distal tip when a vacuum is applied to the proximal end of the aspiration lumen and the distal tip is engaged with a clot. Furthermore, a higher number of crowns or a higher ratio of crowns to circumferential length increases the resistance to collapse of the distal tip including the expandable membrane and the expandable support structure when a vacuum is applied at the proximal end of the aspiration lumen and the distal tip is engaged with a clot (or clogged by a clot or other material). Furthermore, having a small cell period further enhances the roundness. Furthermore, having a small cell amplitude can further enhance the roundness.

[0035] For example, in embodiments including support structures containing support elements, 40 crowns per ring in a delivered 2 mm outer diameter expandable tip would typically be sufficient to maintain roundness after expansion, while 60, 80, 100 or more crowns per ring can be required to provide the same support as a support structure not including support elements. Thus, the number of crowns per ring in a delivered support structure (e.g., including support elements) having a 2 mm outer diameter would typically be in the range of 30 to 75, preferably in the range of 40 to 75, and more preferably in the range of 50 to 60. The range for rings without support structures would be 60 to 150, preferably 70 to 120, more preferably 100 to 120. For embodiments including support elements, the ratio of the number of crowns to the circumference (in mm) would be in the range of 3 to 10, preferably in the range of 4 to 9, more preferably in the range of 4.5 to 8, and most preferably in the range of 5 to 7, while for embodiments without support elements, the ratio of the number of crowns to the circumference (measured in mm) would be in the range of 5 to 18, preferably in the range of 6 to 12, more preferably in the range of 8 to 12, and most preferably in the range of 10 to 12.

[0036] Exemplary closed cell support structures can include "box-shaped" structures linked end-to-end by links in a circular, helical or other pattern. Typically, the boxes would be linked by circumferential links to form a circular ring, which in turn is linked by axial links to form a support stent or other support structure. Alternatively, the circumferential links can be arranged in a helical or spiral pattern to form a continuous series of rings, preferably without additional axial links or attachment points.

[0037] While the boxes would typically be square, diamond or rectangular, the boxes can have any closed polygonal structure, including multiple straight sides (sometimes curved sides) linked by curved sections. In some cases, circular and elliptical closed shapes can also be considered boxes within the scope of the present invention. Such box structures would be configured to elongate circumferentially (expand) when a radially opening force is applied inside the support structure in the distal tip of the aspiration catheter.

[0038] In preferred examples, the expandable distal tip including the expandable support structure has an outer diameter in the delivery configuration of about 1 mm, 2 mm, 3 mm, 4 mm, or about 5 mm, or the expandable distal tip including the expandable support structure has an outer diameter in the delivery configuration in the range of 1 mm to 5 mm. In other examples, the distal tip including the expandable support structure has an outer diameter in the delivery configuration of about 7 mm, 8 mm, 9 mm, or about 10 mm. Typically, the distal tip has a cylindrical shape in the delivery configuration. In some other examples, the distal tip can have other shapes in the delivery configuration, such as a funnel shape, a cone shape, a rectangular shape, an oval shape, or other shapes. In yet another example, the distal tip includes an expandable support structure, wherein the distal tip has a cylindrical shape, a rectangular shape, an oval shape, a cone shape, a funnel shape, or other shape in the expanded configuration, wherein the outer diameter of the distal tip in the expanded configuration ranges from 2 mm to 10 mm, preferably ranges from 3 mm to 8 mm, and more preferably ranges from 3 mm to 7 mm. The outer diameter of the distal tip can vary along the length of the distal tip or around the circumference of the distal tip, or can be fixed or constant along the length of the distal tip or around the circumference of the distal tip.

[0039] In some cases, the stent or other support structure will also include support elements that will help support the spaces that open up in the support structure as it expands. For example, in a support structure that includes serpentine rings including crowns and struts, as the rings expand, the struts will separate and leave an unsupported space or gap in between. The gaps between adjacent rings will also be unsupported spaces before and after the support structure expands radially. The membrane will lack support in those gaps, and both the roundness and / or the crush strength (crush resistance) of the expanded distal tip will be reduced. Moreover, this unsupported area of the membrane will be at greater risk of invagination (the membrane and / or expandable support structure collapsing or partially collapsing) when negative pressure is applied to the suction lumen of the catheter as it engages a clot, particularly when the open distal tip is partially or fully obstructed by a clot, or when the expandable tip is delivered to the vasculature in the delivery configuration.

[0040] The support elements of the present invention will be configured to fill as many of the open spaces within the rings as possible. Conversely, the spaces or gaps between axially adjacent rings will preferably be free of support elements (although in some examples there will typically be axial links and other portions of the support structure, and in other examples the spaces or gaps between axially adjacent rings can be free of any support elements or attachment points, and free of any portions of the support structure). The spaces between adjacent rings should have the least number of support structures, if any, to enhance flexibility, particularly in the unexpanded delivery configuration.

[0041] In certain embodiments, in the unexpanded delivery configuration, the support elements of the present application will cover or fill 50% to 98%, preferably 65% to 95%, more preferably 75% to 95%, and most preferably 80% to 95% of the unsupported area within each loop. Conversely, in the expanded configuration (i.e., after deployment in the blood vessel), the support elements of the present application will cover or fill 10% to 85%, preferably 15% to 85%, more preferably 20% to 85%, and most preferably 40% to 85% of the unsupported area within each loop.

[0042] Preferred support elements will "overhang" from the loops and be configured to fill or support the opening or gap within the "axial width" of the loop, generally remaining outside the gap and space between adjacent loops so as to support the distal tip after radial expansion of the distal tip without significantly reducing the flexibility of the distal tip as it is advanced into the vasculature, or without reducing the flexibility of the distal tip as it is advanced into the vasculature, or both. Exemplary support elements have a base end (proximal end) and a free end (distal end). The base end is typically attached to one of the radially expandable loops (e.g., to a loop structural element such as a crown or strut), and the free end is typically directed toward the gap between adjacent loops, generally not extending into the gap between adjacent loops in the delivery configuration. In a preferred example, the expandable support structure includes a plurality of support elements within each loop, the plurality of support elements each having a width, length, and thickness sufficient to support the unsupported space (or area) within the loop to prevent collapse or invagination (partial collapse) of the unsupported area when a vacuum is applied to extract the engaging clot at the distal end of the aspiration catheter. In another example, the expandable support structure includes a plurality of circumferential loops, wherein at least some of the loops include at least some support elements configured to resist collapse or resist invagination of the unsupported area when a vacuum is applied at the proximal end and the clot engages the distal end of the aspiration catheter. In yet another example, the expandable support structure includes a plurality of circumferential loops, wherein at least some of the loops include at least some support elements configured to resist collapse or resist invagination of the unsupported area when a vacuum is applied at the proximal end and the clot engages the distal end of the aspiration catheter.

[0043] In some cases, the support elements can even extend into the adjacent gaps between adjacent rings prior to the distal tip being radially expanded, but preferably most or all of the support elements are configured to be recessed (or confined) within the axial width of the rings (or within the amplitude of the ring cell) prior to the rings being expanded, and to further extend, further protrude, or to be further exposed or to enter into the adjacent gaps between adjacent rings upon (or only after, or during) the distal tip being radially expanded. It has been found that having support structures in the gaps between adjacent rings prior to the distal tip being expanded will reduce the flexibility of the tip during advancement in the vasculature prior to the distal tip being deployed. This loss of flexibility is undesirable.

[0044] Using such "overhanging" support elements as "support for the unsupported areas or gaps within the axial width of the rings", these support elements are deployed to enhance the support of the expandable membrane after the distal tip is deployed, without increasing the rigidity of the distal tip during delivery (introduction and advancement) of the aspiration catheter into and through the vasculature of a patient. Using support elements also allows for increasing the expansion of the distal tip (and thus the diameter of the usable aspiration lumen), while resisting collapse when vacuum is applied at the proximal end of the aspiration lumen. In another example, upon (or after) the distal tip being expanded, the support elements are deployed (or protrude, or further extend) towards or into the gaps between two adjacent rings to enhance the support of the expandable membrane after the distal tip is deployed, without increasing the rigidity of the distal tip during delivery (introduction and advancement) of the aspiration catheter into and through the vasculature of a patient.

[0045] The support elements can have various shapes and configurations, such as I, T, U, M, Z, curved, straight, or other shapes and configurations, to support or enhance the support of the unsupported segments of the expandable membrane, preferably without increasing the rigidity of the distal tip. The free end can have a flat shape, a circle, a sphere, or other shapes. The width of the support elements can be the same or different along the length of the support elements. The support elements can be tapered, with the width increasing or decreasing in the direction from the attached base end to the free distal end.

[0046] In preferred cases, the size of the support elements will preferably be chosen to fill or occupy as much of the un-filled space or gap that can exist within any given ring (but generally not between adjacent rings) of the support structure prior to expansion as possible. For example, the gap between the struts of a crown joined by a crown can be filled with support elements overhanging the inner curve of the crown, as illustrated in many embodiments herein. The overhanging support elements can be patterned to virtually fill the entire space between the struts, leaving only a cutout or very small separation line therebetween. By maximizing the area of the support elements prior to expansion, the coverage of the gaps created after expansion is also maximized between the struts after expansion of the rings. In preferred examples, the width of the support elements at the base end of attachment is about equal to or greater than the width of the structural elements (e.g., struts, crowns, or links) to the location at which the support elements are attached.

[0047] While the support elements and the expandable support structure are typically formed of the same material, in some cases they can be formed of different materials or different types of materials, for example, (1) one can be formed of a metal and the other can be formed of a polymer, or (2) one can be formed of a metal or a polymer and the other can be formed of a different metal or a different polymer.

[0048] In another preferred example, the support elements are recessed into the space between the structural elements of a ring, for example, into the space between the struts joined by a crown, such that the distal end of the support elements in the delivery configuration does not substantially extend beyond the peak of the adjacent crown or other structural element into the gap between adjacent rings.

[0049] In specific examples, the support elements can have one base end and one free end, two free distal ends, three free distal ends, or more.

[0050] In another example, the support elements can have two or more base ends, each attached to one or more structural elements on one ring (the same ring). Such support elements can have one, two, three, or more distal free ends.

[0051] In another example, the support elements can be split into two parts to have at least two base ends, each attached to a different structural element on a single ring. The base ends of the support elements can be attached to the axial inner surface or the axial outer surface of the ring, or to the axial inner surface or the axial outer surface of the structural elements (including crowns, struts, or links) of the ring.

[0052] In a specific example, the radially expandable ring is disposed within a cylindrical "envelope" prior to expansion. The cylindrical envelope is a virtual space having an inner generally cylindrical surface and an outer generally cylindrical surface and an annular volume therebetween, wherein the radially expandable ring is sized and disposed so as to be within the space prior to expansion. Typically, the support elements are also configured to be within the virtual cylindrical envelope prior to expansion of the ring. The diameter of the cylindrical envelope can be greater than, equal to, or less than the diameter of the tubular catheter body prior to expansion.

[0053] In a specific example, the distal tip of the expandable support structure can be configured to expand to a cylinder, a cone, or a combination thereof after expansion to an expanded configuration. In a preferred example, the distal tip of the expandable support structure can be configured to expand from a cylindrical configuration to an expanded cylindrical configuration, an expanded conical configuration, or an expanded conical distal tip configuration to maximize or enhance the suction force when a vacuum is applied at the proximal end of the suction lumen. In another example, the distal tip of the expandable support structure can be configured to expand from a cylindrical configuration in the delivery configuration to a substantially cylindrical configuration after expansion of the expandable support structure to an expanded configuration, wherein the expanded configuration is greater than the delivery configuration, or wherein the expanded configuration is in the range of 1.1 to 4 times greater than the delivery configuration, preferably 1.3 to 3 times greater. In yet another example, the distal tip of the expandable support structure is configured to expand from a cylindrical configuration at a proximal segment of the distal tip to an expanded conical configuration and is continuously connected to an expanded cylindrical configuration distal to the expanded conical configuration. In further other configurations, the expanded configuration can be a combination of a long conical proximal end base (typically at least a short conical portion at the proximal end) and a distal end cylindrical portion attached to the proximal end of the shaft. Many specific configurations are illustrated in the figures.

[0054] In a specific example, the expandable support structure is configured to expand in response to expansion of a balloon catheter within the expandable support structure. The balloon catheter can be configured to be delivered with the aspiration catheter comprising the expandable support structure at the distal end, typically within the aspiration lumen of the aspiration catheter, the balloon catheter being delivered with the aspiration catheter with the distal tip of the aspiration catheter positioned at the distal end of the aspiration catheter proximate to the clot, whereupon the balloon catheter expands to expand the expandable support structure to the expanded configuration, and then the balloon catheter deflates and is withdrawn from the aspiration catheter prior to application of vacuum at the proximal end of the aspiration catheter to remove the clot. In another example, after the aspiration catheter is delivered to the clot and positioned proximate to the clot, the balloon catheter is delivered to the distal end of the aspiration catheter, where the balloon catheter is advanced through the aspiration catheter until the balloon reaches the expandable distal tip segment or to the expandable distal tip, whereupon the balloon expands to expand the distal tip segment of the aspiration catheter, and then deflates and is removed from the aspiration catheter, and vacuum is applied at the proximal end of the aspiration catheter to remove (withdraw) the clot. In another example, the expansion catheter has an expandable member at the distal end of the catheter that expands to expand an expandable distal tip comprising an expandable support structure (stent) and an expandable membrane, where the distal tip is incorporated into or coupled to the distal end of the aspiration catheter, where the expandable member comprises a balloon, a stent, a cage, or other expandable structure to expand the expandable support structure from a delivery configuration to an expanded configuration. The expandable member can be a polymeric material, a metallic material, or other material, where the member is expandable from a delivery configuration, a crimped configuration, or a deflated configuration to an expanded configuration. While the distal tip can be fully expanded along its entire length, typically only a portion of the length of the distal tip can be expanded by the balloon or other expandable member, depending on the patient's anatomy or other circumstances. The portion of the distal tip that is expanded can be controlled by adjusting the length of the balloon present in the distal tip during expansion and / or selecting an expansion balloon having a different length.

[0055] In a preferred example, the expandable support structure of the distal tip of the aspiration catheter is formed of a deformable material, preferably a plastically deformable material. In a preferred example, the expandable support structure is formed of a plastically deformable metal or metal alloy. In a specific example, the expandable support structure is formed of a metallic material comprising a stainless steel alloy, a cobalt-chromium alloy, a platinum-chromium alloy, or other metal or metal alloy.

[0056] The expanded shape of the support structure will generally be determined by the shape of the balloon or other expansion structure, that is, expansion of a cylindrical balloon within a plastically deformable support structure will cause the distal tip to assume a cylindrical shape, while expansion of a conical balloon will cause the distal tip to assume a conical shape.

[0057] In some less preferred examples, the expandable support structure can be configured to self-expand upon release from radial constraint. The radial constraint can be positioned on the expandable support structure. In other examples, the radial constraint can be positioned within the expandable support structure (lumen) and configured to release the expandable support structure in vivo to allow the expandable support structure to expand. In one example, the expandable support structure is formed of a shape memory material such as NiTi / Nitinol or other shape memory material.

[0058] The support elements can have one or more of a variety of shapes and attachment locations on the expandable structure. For example, the support elements can extend in an axial direction to a radially expandable ring, towards a gap between adjacent rings, or into a gap between adjacent rings. In other examples, the support elements can extend in a circumferential direction to a radially expandable ring, typically attaching to an outwardly curved surface of a crown (peak), circumferentially into an adjacent gap. In other examples, the support elements can extend in an axial direction to a radially expandable ring, into a gap contained within or defined by the axial width of the ring, or contained within or defined by the space between each ring or structural element of the rings, typically attaching to a curved surface of a crown. In further other examples, at least some of the support elements can include any one or more of linear and / or non-linear segments, can have an expanded tip at a free end (forming a contact pad discussed below). In some examples, the support elements can branch into two or more segments in a direction towards the free end. The support elements can have the same or different lengths or widths. In some specific examples, the length of the support elements can be equal to or less than the length of an adjacent strut in the delivery configuration. In other examples, the length of the support elements can be equal to or less than the ring cell amplitude in the delivery configuration, or less than 1 times the ring cell amplitude in the delivery configuration. In yet another example, the length of the support elements can be equal to or less than the length of a ring period in the delivery configuration. In other examples, the length of the support elements can be greater than the ring cell amplitude only in the expanded configuration.

[0059] In some examples, the support elements attach to one or more of an axial inner crown region, an axial outer crown region, a strut, a middle strut, or to an axial or circumferential link.

[0060] In some preferred examples, at least some of the radially expandable rings comprise a serpentine, zigzag, box, diamond, or other pattern comprising struts joined by crowns, and at least some of the adjacent rings are joined, for example, using welding, adhesion, or fusing of the crowns on adjacent rings or through axial links or attachment points at one or more locations as patterned. Alternatively, at least some of the adjacent rings can be joined end-to-end in a helical arrangement without axial links or attachment points, and wherein preferably the amplitude on at least some of the rings is fixed within each ring. In preferred examples, at least two adjacent rings or at least some of the adjacent rings of the expandable support structure distal tip have no more than two links or two attachment points joining the at least two adjacent rings (or the at least some adjacent rings). In another example, a plurality of circumferentially expandable rings are included, the plurality of circumferentially expandable rings comprising struts joined by crowns, wherein one or more adjacent rings are axially separated by a gap and are not connected, typically one or more of the non-connected adjacent rings are located at a distal end of the distal tip of the aspiration catheter, and are held together by an expandable membrane attached to the one or more adjacent non-connected rings, thereby providing enhanced flexibility to the distal tip in the delivery configuration and allowing expansion of the one or more rings from the delivery configuration to the expanded configuration. In preferred examples, the expandable support structure comprises a plurality of adjacent expandable rings, wherein along the length of the expandable structure, adjacent rings have two or fewer connectors or attachment points joining the adjacent rings, preferably adjacent rings have one connector or attachment point joining the adjacent rings, wherein the length is the entire length of the expandable structure, or a segment along the axial length of the expandable structure, wherein the segment comprises two or more rings. In yet another preferred example, the expandable support structure comprises a plurality of adjacent rings joined end-to-end in a helical arrangement to enhance flexibility of the aspiration catheter to navigate through tortuous anatomy in the delivery configuration. Adjacent rings in this example are not joined through links or attachment points on adjacent rings, and at least some of the adjacent rings each have a fixed (or constant or identical) ring cell amplitude, preferably all of the at least some rings have a fixed (or constant or identical) ring cell amplitude. In this example, at least some of the rings can be patterned along the length of the expandable stent as an open cell pattern, a closed cell pattern, or a combination of open and closed cell patterns.

[0061] Alternatively, in another example, at least some of the adjacent rings in the expandable support structure can be joined end-to-end in a helical arrangement. Such a helical arrangement will typically include a "smooth" helix without additional curves or bends, i.e., a curve formed on a conical or cylindrical surface that would become a straight line if the surface were unrolled into a plane. In other cases, one, two, three, or more additional bends, curves, or other secondary non-linearities can be superimposed on the helical rings to enhance the bendability of the expandable structure, particularly in a crimped or reduced-diameter configuration during delivery. Such one, two, three, or more additional bends, curves, or other secondary non-linearities can be formed by the expandable support structure or by a non-expandable structure. In a particular preferred example, the expandable support structure forms a helical coil.

[0062] In other preferred examples, the extensible film can comprise an elastic film or a non-elastic film (stretchable film). The elastic film and / or non-elastic film can comprise one or more elastomers, polymeric materials, or other materials. In preferred examples, the extensible film is selected from NeuSoft UR862A, NeuSoft UR852A, NeuSoft UR842A, NeuSoft NEU 455-50A, NeuSoft™ 596-50A, NeuSoft NEU 455-55A, NeuSoft NEU 455-60A, NeuSoft NEU 455-65A, Tecothane AR-62A, Tecoflex EG 80A, Tecoflex EG 85A, Tecoflex EG-93A, Tecoflex TT-1074A, Tecoflex TT-1085A, Tecoflex TT-18095A, Elastollan S 50 A 15SPF, Elastollan S 60 A 10W, Elastollan S 60 A 10WH, Pellethane 2103-70A, Pellethane 70A, Pellethane 2363-80A, Estane 2103-70A, ReZithane Rx50A, Texin RXT 70A, Chronoflex C 80A-Q, Chronoflex AL 75A-Q, Chronoflex C 80A-Q, Polyblend 1100-75A, ResMart Ultra TPU 60A, ResMart Ultra TPU 70A, ResMart Ultra TPU 85A, ResMart Ultra TPU 90A, ResMart Ultra TPU 95A, Ecoflex 00-30, Ecoflex 00-20, Ecoflex 5A, Dragon Skin 20, Pebax 2533, Pebax 3033, chronoprene, chronothane, chronosil, polyethylene (such as LDPE, HDPE, Ultra HMWPE, etc.), Pebax (such as Pebax 2533, Pebax 3533, Pebax 4033, Pebax 4533, Pebax 5533, Pebax 7233, etc.), nylon (such as Nylon 12, Nylon 6 / 6, or Nylon 6), polyurethane (such as Pellethane 2363-55D, Pellethane 2363-65D, ResMart Ultra TPU 60A, ResMart Ultra TPU 70A, ResMart Ultra TPU 85A, ResMart Ultra TPU 90A, ResMart Ultra TPU 95A, etc.), silicone (such as Dragon Skin 20, etc.), or other materials.64D, ResMart Ultra TPU 72D), fluoropolymers (such as PTFE, poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride-co-hexafluoropropylene), fluorinated ethylene propylene, polychlorotrifluoroethylene, etc., or combinations thereof, or other elastomers, polymers, or other materials.

[0063] In one example, the expandable membrane is composed of a polymeric elastic membrane, which can be isotropic, but in other cases can be anisotropic, for example, the elastic membrane can have a higher elasticity in the circumferential or radial direction than in the axial direction.

[0064] In some cases, the expandable membrane can be formed by heat shrinking or heat shrinking onto an expandable support structure, such as a stent. In other cases, the expandable membrane can be formed by laminating an expandable support structure, such as a support stent, between two or more layers of polymeric material, such as an elastomeric material, an elastomeric on an outer surface and a non-elastic / stretchable polymeric material on an inner surface of the expandable structure, a stretchable / non-elastic material on an outer surface and an inner surface of the expandable structure, or a stretchable material on an outer surface and an elastic material on an inner surface of the expandable structure. For example, two layers of elastomer, two layers with one elastic layer and one stretchable layer, or two layers that are both stretchable, can be adhered to (sandwiched on) an expandable support structure, such as a support stent, such that the two layers are sealed or adhered between each other and the two layers are sandwiched on, adhered and / or adhered to the stent or other expandable structure. In another example, the expandable membrane includes a polymer or other material that is configured to stretch and / or expand from a delivery configuration to an expanded configuration, where the material is configured to expand from the delivery configuration to a larger configuration that is 1.1 to 5 times the delivery configuration. The expandable membrane is configured to have axial, radial, and / or circumferential stiffness to allow radial flexibility while maintaining axial thrust transmission. The expandable membrane is configured to allow radial expansion of the expandable support structure and / or to allow axial movement of the expandable support structure ring as the ring expands from the delivery configuration to the expanded configuration.

[0065] In one preferred example, the aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending between the proximal end and the distal end. The aspiration catheter has an expandable distal tip having a central passage in communication with the aspiration lumen of the tubular catheter body, the expandable segment comprising an expandable support structure is attached to or embedded within an expandable membrane. In one preferred example, the expandable support structure is patterned from a tube, a curved wire, or a rolled patterned sheet pattern. The tube, rolled sheet, or curved wire in preferred examples is patterned as the expandable support structure that is expandable from a delivery configuration to an expanded configuration. In some other preferred examples, the aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending between the proximal end and the distal end. The aspiration catheter has an expandable distal tip having a central passage in communication with the aspiration lumen of the tubular catheter body. The expandable support structure is attached to or embedded within the expandable distal tip of the tubular catheter body. The tubular catheter body can be reinforced over at least a portion of its length (proximal to the expandable tip) with a reinforcement structure by one or more of a coil, a stent, a stent with support features, or other device. In some cases, at least a portion of the catheter body reinforcement structure comprises one or more of a coil, a stent, or a braid, which can be formed continuously with the expandable support stent or other expandable support structure of the expandable tip. In preferred examples, the reinforcement structure and the expandable stent or other expandable support structure are formed from a patterned tube. In other examples, the reinforcement structure and the expandable stent or other expandable support structure are formed from a curved wire. In other cases, the reinforcement structure in the catheter body can be formed separately from the support stent of the expandable distal tip, then coupled or joined together by one or more of welding, fusing, bonding, or braiding the structures together, overlapping them over a length segment at their interface, or one or more of the above.

[0066] In another example, an aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending between the proximal end and the distal end. The aspiration catheter has an expandable distal end having a central passage connected to the aspiration lumen of the tubular catheter body, the expandable distal end including an expandable support structure attached to or embedded within an expandable membrane. In one specific example, the expandable distal end including the expandable support structure has a length ranging from 0.5 mm to 50 cm, preferably ranging from 1 cm to 25 cm, and more preferably ranging from 2 cm to 10 cm. In yet another example, the expandable distal end can have a length spanning substantially the length of the aspiration catheter. In specific examples, the expandable distal end can have a length ranging from 50 cm to 150 cm. In preferred examples, the expandable distal end includes an expandable distal tip, where the distal tip includes a segment of the expandable support structure attached to or embedded within the expandable membrane. In some specific examples, the expandable distal tip segment includes the expandable distal end segment. In other cases, the expandable distal tip is the same as the expandable distal end.

[0067] In other preferred examples, the base ends of at least some of the plurality of support elements can each be attached to a strut. In other preferred embodiments, the base ends of at least some of the plurality of support elements can each be attached to an inner or outer curved surface of the crown. The support elements can extend or be oriented axially, circumferentially, or at other angles or directions relative to the support stent or other expandable support structure, the support stent ring, or structural elements of the stent ring.

[0068] In a second aspect, the present invention provides an aspiration catheter having an alternative expandable support structure design. The alternative aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and a lumen extending between the proximal end and the distal end. An expandable support structure is attached at or incorporated into the distal end or distal tip of the tubular catheter body and has a central passage connected to the lumen of the tubular catheter body, and the expandable support structure includes an expandable membrane and an expandable stent or other expandable support structure configured to radially expand the expandable membrane. The expandable membrane is typically elastically expandable, and the expandable stent or other expandable support structure is typically non-elastically expandable, i.e., the stent plastically deforms into an expanded shape and size in response to radial expansion by a balloon or other radial expansion tool and retains the expanded shape and size. In this way, in the expanded configuration, the expanded support structure "supports" the membrane.

[0069] In other cases, the membrane can be plastically expandable or otherwise inelastically expandable, while the support structure is elastic or inelastic, although such embodiments are generally not preferred.

[0070] The expandable support structure can include a plurality of radially expandable rings arranged along the longitudinal axis, where at least some of the radially expandable rings include "expandable cells" having a curvature that can plastically deform to allow the ring to open radially. The cells can have an "open" configuration, such as U-shaped cells in a serpentine ring and V-shaped cells in a zigzag ring; squares, rectangles, or other regular or irregular polygons with one or more missing sides; and The cells can alternatively have a "closed" configuration, such as diamond or box-shaped cells in a box-shaped ring, where the box shape can be rectangular, square, or the like or other regular or irregular polygonal shape.

[0071] The support elements can be located inside or outside of the open cells. For example, the base of a cantilevered support element can be attached to the inner curved surface of the crown and located between adjacent struts in a U-shaped, V-shaped, or The base of a cantilevered support element can alternatively be attached to the outer curved surface of the crown and extend away from the struts into the gap near the U-shaped, V-shaped, or The base of a cantilevered support element can alternatively be attached to the outer curved surface of the crown and extend away from the struts into the gap near the U-shaped, V-shaped, or

[0072] The support elements can also be located inside or outside of the box or other closed cells. For example, the base of a cantilevered support element can be attached to the inner surface of the box and protrude into the interior space of the box. The base of a cantilevered support element can alternatively be attached to the exterior of the box or to a circumferential link that attaches the boxes or other closed cells together to form a ring.

[0073] Typically, at least one end of the support elements is attached to at least one location on the struts or crown or ring in the radially expandable ring. However, in some cases, at least some of the support elements can not be attached to the support scaffold or other expandable support structure, but rather are only attached to or coupled to the expandable membrane, so that they reinforce the V-shaped, shaped, U-shaped, or square / box-shaped space between the struts, to enhance the resistance of the expandable membrane to collapse under vacuum / negative pressure when the distal tip is occluded or blocked by a clot or other material.

[0074] In some cases, at least some of the support elements can extend in a circumferential direction from the radially expandable ring into the cell space (V-shaped, In preferred examples, at least some of the support elements extend circumferentially from the outer crown region to an adjacent outer crown region in one direction or in two opposite directions. In another preferred example, at least some of the support elements extend circumferentially from a strut to an adjacent strut in one direction or in two opposite directions. In other cases, at least some of the support elements extend in an axial direction from the radially expandable rings into the cell space (V-shaped, In preferred examples, the support features are configured to shorten when the expandable support structure is expanded to the expanded configuration such that the support features are equal to or less than the amplitude of the expandable ring cells in length, or the support features do not extend axially beyond the peaks of adjacent crowns. In another preferred example, the support features are configured to further unfold or protrude when the expandable support structure is expanded to the expanded configuration, providing enhanced support for the expandable membrane and enhanced collapse resistance for the expandable membrane when a vacuum is applied at the proximal end of the aspiration lumen.

[0075] In preferred examples, the present invention provides an aspiration catheter having an expandable support structure design. The aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and a lumen extending between the proximal end and the distal end. An expandable support structure is attached at or incorporated into the distal end (or distal tip) of the tubular catheter body and has a central passage that is connected to the lumen of the tubular catheter body, and the expandable support structure includes an expandable membrane and a support scaffold or other expandable support structure configured to expand the expandable membrane radially. The expandable support scaffold or other expandable support structure includes a plurality of radially expandable rings arranged along a longitudinal axis, where at least some of the radially expandable rings include a serpentine or zigzag or other open pattern that includes struts connected by crowns, the struts forming V-shaped, spaces between the struts. A plurality of support elements are positioned in the V-shaped, spaces to support the membrane in the V-shaped, spaces in the delivery configuration and / or the expanded configuration, and where the support scaffold or other expandable support structure resists collapse of the membrane in the spaces in the expanded membrane and scaffold or other expandable support structure configuration when a vacuum is applied at the proximal end of the aspiration lumen and the distal tip is occluded or blocked by a clot or other material, and where the support scaffold or other expandable support structure is capable of collapsing from the expanded configuration to a smaller configuration when the aspiration catheter is withdrawn into a guide catheter having a smaller inner lumen configuration than the expanded configuration of the support scaffold or other expandable support structure.

[0076] In preferred examples, the present invention provides an aspiration catheter having an expandable support structure design. The aspiration catheter includes a tubular catheter body having a proximal end, a distal end, and a lumen extending between the proximal end and the distal end. An expandable support structure is attached at the distal end (or distal tip) of the tubular catheter body and has a central passageway in communication with the lumen of the tubular catheter body, and the expandable support structure includes an expandable membrane and a support scaffold configured to radially expand the expandable membrane. The expandable support scaffold includes a plurality of radially expandable rings arranged along a longitudinal axis, wherein at least some of the radially expandable rings include a serpentine or zigzag or open pattern including struts joined by crowns, the struts forming cell spaces therebetween. A plurality of support elements are located in the cell spaces to support the membrane in the cell spaces in a delivery configuration and / or an expanded configuration, and wherein the support elements resist collapse of the membrane in the spaces in the expanded membrane configuration when a vacuum is applied at the proximal end of the aspiration lumen and the distal tip is occluded or blocked by a clot or other material, and wherein the support elements allow the expandable support structure to collapse from the expanded configuration to a smaller configuration when the aspiration catheter is withdrawn into a guide catheter having a smaller inner lumen configuration than the expanded configuration of the support structure.

[0077] In a third aspect, the present invention provides a method for aspirating a clot from a patient's vasculature. The method includes positioning the distal end of the expandable support structure of any of the aspiration catheters in the patient's vasculature at or near the clot region. The expandable support structure is expanded, typically by balloon expansion (but alternatively by self-expansion) to engage the clot or to engage the vessel wall near the clot region. A negative pressure (vacuum) is applied to the proximal end of the aspiration lumen in the catheter body to aspirate the clot into the aspiration central passageway of the expanded expandable structure.

[0078] In preferred examples, the present invention provides a method for aspirating a clot from a patient's vasculature. The method includes positioning the distal tip of the expandable support structure of any of the aspiration catheters in the patient's vasculature at or near the clot. The expandable support structure is expanded, typically by balloon expansion but alternatively by self-expansion, to an expanded configuration to engage the clot or to engage the vessel wall near the clot. A vacuum is applied to the proximal end of the lumen in the catheter body to aspirate the clot into the central passageway of the expanded expandable structure, at least a portion of the expandable support structure optionally collapses from the expanded configuration to a smaller configuration prior to removal from the vasculature.

[0079] In a fourth aspect, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. A distal tip has a proximal end incorporated into or attached to the distal end of the tubular catheter body and a central passage (aspiration lumen) longitudinally connected to the lumen of the tubular catheter body. The distal tip is adapted to expand from a delivery configuration to a radially expanded configuration or from a radially collapsed configuration to a radially expanded configuration in response to a radially outward expansion force applied within the distal tip segment, and the distal tip comprises an expandable membrane and an expandable support structure (such as a stent), wherein the expandable stent or other expandable support structure comprises a plurality of rings spaced apart along the longitudinal axis with gaps between the plurality of rings. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform in response to the radially outward expansion force applied from within the distal tip to expand the stent or other expandable support structure circumferentially.

[0080] In some cases, the expandable membrane is attached to the inner and / or outer surface of the expandable stent or other expandable support structure. In other cases, the expandable stent or other expandable support structure is embedded in or within the expandable membrane, where the expandable membrane comprises at least two membranes, one attached to the outer surface of the expandable stent or other expandable support structure and the other attached to the inner surface of the expandable stent or other expandable support structure. In other cases, the aspiration catheter comprises an expandable tip, where the expandable tip comprises an expandable membrane and an expandable support structure, such as a stent, where the expandable stent or other expandable support structure comprises a plurality of rings spaced apart along a longitudinal axis, with gaps between the plurality of rings and within each ring, where the rings comprise structural elements comprising struts and crowns. The expandable stent or other expandable support structure is embedded in or within the expandable membrane, where the expandable membrane comprises at least one membrane, where the at least one membrane softens and / or melts on the outer surface of the expandable stent or other expandable support structure and / or on the inner surface of the expandable stent or other expandable support structure, allowing the expandable membrane to protrude or flow into the gaps present within the ring structural elements and between adjacent rings, adhere to the rings and ring structural elements, providing a unified (integrated) expandable stent / membrane system that can expand from a collapsed or delivery configuration to an expanded larger configuration. In a preferred aspect, the expandable membrane covers the outer and / or inner surface of the expandable structure and also covers, where the covering comprises one or more of filling, flowing into, or protruding into at least some of the gaps present within each ring of the expandable stent or other expandable support structure and the gaps present between adjacent rings of the expandable stent or other expandable support structure, where the flowing membrane sufficiently adheres to the stent or other expandable support structure ring structural elements to provide a unified system (integrated system) capable of expanding from a delivery configuration to an expanded configuration as an integrated system. The expandable membrane of the preferred aspect flows into the gaps present between each ring, within each ring the structural elements comprise struts joined by crowns, where the one or more expandable membranes of the preferred aspect cover the outer and / or inner surface of the expandable stent or other expandable support structure, cover at least some of the side surfaces of the expandable stent structural elements, preferably cover substantially all of the side surfaces of the expandable stent structural elements, and cover substantially all of the gaps between adjacent rings of the expandable stent or other expandable support structure. The expandable stent or other expandable support structure of the preferred aspect comprises an outer surface, an inner surface, and two side surfaces. In other aspects, the expandable stent or other expandable support structure is formed from a curved wire comprising an outer surface and an inner surface.

[0081] In some cases, the stent or other expandable support structure has a delivery configuration or radially collapsed (e.g., crimped) delivery configuration and an expanded deployed configuration. Typically, the maximum outer diameter of the radially collapsed configuration ranges from 0.5 mm to 30 mm, often from 1.0 mm to 5 mm, and more often from 2 mm to 5 mm, and the maximum outer diameter of the radially expanded configuration ranges from 1 mm to 60 mm, preferably from 1.5 mm to 45 mm, more preferably from 3 mm to 45 mm.

[0082] In some cases, the distal tip can be configured to expand from an initial cylindrical shape to an enlarged cylindrical configuration in response to a radially outward expanding force applied within at least a portion of the distal tip. In other cases, the distal tip is configured to expand from an initial cylindrical shape to an enlarged conical configuration in response to a radially outward expanding force applied within at least a portion of the distal tip. In preferred examples, the enlarged conical configuration terminates at a distal end of the distal tip, thereby providing a maximum area (cross-sectional area) for clot extraction.

[0083] In some cases, the tubular catheter body can have a working length ranging from 50 cm to 200 cm, an outer diameter ranging from 0.5 mm to 30 mm, and an inner lumen diameter ranging from 0.25 mm to 25 mm, from the proximal end to the distal end.

[0084] In some cases, the distal tip can have a bending resistance in its initial radially collapsed configuration or delivery configuration of less than 1 N, preferably less than 0.5 N, more preferably less than 0.3 N, and most preferably less than 0.2 N, as measured by a three-point deflection test (described in greater detail below). The distal tip can also have a collapse pressure (vacuum) in its radially expanded configuration of equal to or greater than 0.5 atm, preferably equal to or greater than 0.75 atm, more preferably about equal to 1 atm, and most preferably greater than 1 atm, when a vacuum is attached to the proximal end and a clot (or embolus) engages and blocks the open distal end of the distal tip. In other examples, the distal tip can have a bending resistance in its initial radially collapsed configuration or delivery configuration ranging from 0.1 N to 2 N, preferably ranging from 0.1 N to 0.5 N, more preferably ranging from 0.1 N to 0.35 N, and most preferably ranging from 0.1 N to 0.2 N.

[0085] Flexibility is a measure of the ability of the distal tip to pass through tortuous anatomy. Lower flexibility indicates a higher flexibility and better ability of the distal tip to pass through tortuous anatomy. Flexibility of the distal tip (or any other portion of the aspiration catheter) can be measured by a three-point deflection test such as the ASTM F2606 standard guide for three-point bending of balloon expandable vascular stents and stent systems or equivalent. A portion of the catheter is placed vertically on two lower static supports with a wedge between them. The spacing of the two supports is 13 mm. While measuring the resistance force, the middle portion of the supported catheter portion is displaced by lowering the wedge held in the upper clamp of an Instron tensile tester (Instron, Norwood, MA, USA) at a deflection rate of 5.0 mm / min. The test is ended when the displacement reaches 2 mm (about 15% of the span length). The three-point flexibility of the catheter portion is equal to the maximum deflection force measurement during the test. Collapse pressure is a vacuum or negative pressure that, when applied to the proximal end of the catheter body lumen, will cause the distal tip to at least partially collapse when the distal tip is completely occluded. By "at least partially collapse" is meant an irreversible contraction (a contraction that does not dissipate after the vacuum is stopped) of more than 5%, more than 10%, or more than 15% of the distal tip lumen diameter or configuration. In a preferred example, the distal tip lumen diameter or configuration including a plurality of expandable rings in an expanded (deployed) configuration is configured to resist collapse of the expandable rings in the expanded configuration when a vacuum is applied at the proximal end of the aspiration catheter and the distal tip is blocked or clogged with a clot or other material; or is configured to resist collapse by contracting any distal tip ring configuration by no more than 5%, no more than 10%, or no more than 15% when the rings are under the applied vacuum in the expanded configuration and the tip is engaged with a clot (or embolus); or preferably by contracting the expanded configuration by no more than 10% under the vacuum; or most preferably by contracting the expanded configuration by no more than 5% under the vacuum. In another example, the distal tip lumen diameter or configuration including a plurality of expandable rings in an expanded deployed configuration resists collapse by contracting any expandable ring by no more than 5% radially under a vacuum of about 1 atm, wherein the no more than 5% radial contraction is substantially reversible to the expanded configuration (i.e., the distal tip lumen diameter or configuration expands to a larger expanded configuration) when the applied vacuum or negative pressure at the proximal end of the catheter body lumen having a central passageway of the distal tip is removed or stopped.

[0086] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. A distal tip has a proximal end attached to the distal end of the tubular catheter body and a central passage in longitudinal communication with the lumen (aspiration lumen) of the tubular catheter body. The distal tip is adapted to expand from a delivery configuration to a radially expanded configuration or from a radially collapsed configuration to a radially expanded configuration in response to a radially outward expanding force applied within the distal tip, and the distal tip comprises an expandable membrane and an expandable support structure (such as a stent), wherein the expandable stent or other expandable support structure comprises a plurality of rings spaced apart along the longitudinal axis with gaps between the plurality of rings. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform in response to the radially outward expanding force applied from within the distal tip to expand the stent or other expandable support structure circumferentially. In a preferred example, the expandable tip comprising the expandable membrane and the expandable stent or other expandable support structure is configured to radially collapse no more than 15%, preferably no more than 10%, more preferably no more than 5% of any expandable ring when a vacuum is applied to the proximal end of the aspiration lumen and the distal tip is engaged with a clot (or embolus), and to passively expand (without the need for an outward expanding force applied within the distal tip by the expandable member) wherein the expanded configuration is greater than the collapsed configuration when the applied vacuum is stopped (or removed), preferably wherein the expanded configuration is greater than the collapsed configuration and substantially the same as the expanded configuration prior to the application of any vacuum. In another example, the lumen diameter or configuration within the distal tip radially collapses no more than 15%, preferably no more than 10%, and more preferably no more than 5% to resist collapse in the expanded deployed configuration under about 1 atm of vacuum, wherein the radial collapse is substantially reversible (i.e., the lumen diameter or configuration within the distal tip expands to a larger configuration, greater than the collapsed configuration under vacuum) when the vacuum or negative pressure applied at the proximal end of the catheter body lumen with the central passage of the distal tip is removed or stopped.

[0087] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending along a longitudinal axis. A distal tip has a proximal end attached to the distal end of the tubular catheter body and a central passage in longitudinal communication with the aspiration lumen of the tubular catheter body. The distal tip is adapted to expand from a delivery configuration (or from a first retrieval configuration) to a first radially expanded configuration in response to a radially outward expanding force applied within the distal tip, wherein the first radially expanded configuration (second retrieval configuration or retrieval configuration) ranges from 1.1 to 2 times the delivery configuration, and wherein the distal tip comprises one or more expandable membranes and an expandable stent, wherein the expandable stent comprises a plurality of expandable rings spaced apart along the longitudinal axis with gaps between the plurality of expandable rings, and wherein the expandable rings comprise structural elements comprising struts joined by crowns. At least some of the rings comprise a malleable metal or metal alloy configured to plastically deform in response to the radially outward expanding force applied within the distal tip, thereby expanding the stent or other expandable support structure circumferentially. The expandable tip comprising one or more expandable membranes and the expandable stent comprising a plurality of expandable rings are configured to radially contract to a first contracted configuration, wherein the first contracted configuration is less than the first expanded configuration but greater than the delivery configuration, preferably wherein the first contracted configuration is no more than 15%, preferably no more than 10%, and more preferably less than 5% of the first expanded configuration when a vacuum is applied to the proximal end of the aspiration lumen, wherein the applied vacuum or when the applied vacuum ranges from 0.75 atm to about 1 atm, and wherein the expandable tip is configured to passively expand to a second expanded configuration, wherein the second expanded configuration is greater than the first contracted configuration and equal to or less than the first expanded configuration when the applied vacuum is removed or discontinued, wherein the expandable tip passively expands without the need for an outward expanding force to be applied within the distal tip by the one or more expandable membranes, and wherein the expandable tip is configured to contract to a second contracted configuration, wherein the second contracted configuration is less than the first contracted configuration and equal to or greater than the delivery configuration when the distal tip is withdrawn into a guide catheter in the patient's anatomy proximal to the distal tip. In one example, the expandable distal tip ranges in length from 0.5 mm to 500 mm, preferably the length ranges from 1 cm to 50 cm, and more preferably the length ranges from 1 cm to 25 cm. In one example, the one or more expandable membranes of the expandable distal tip extend proximally beyond the proximal end of the distal tip of the aspiration catheter. In another example, the one or more expandable membranes of the expandable distal tip have about the same length as the expandable stent, and both are incorporated within the distal end of the aspiration catheter or attached to the distal end of the aspiration catheter proximally of the distal end. In yet another example, the one or more expandable membranes extend from the distal end of the distal tip to the proximal end of the aspiration catheter.

[0088] In some cases, the distal tip including the expandable stent or other expandable support structure has a minimum bend radius of 5 mm, preferably 3 mm, more preferably 2 mm, without deformation and / or kinking in its delivery configuration or radially collapsed configuration, and preferably a minimum bend radius of 10 mm, preferably 6 mm, more preferably 2 mm, without deformation and / or kinking in its radially expanded configuration. The minimum bend radius can be determined by bending the distal tip around a cylinder of known radius and observing whether the distal tip deforms and / or kinks.

[0089] In some cases, the rings of the expandable stent or other expandable support structure span a length in the range of 0.25 mm to 500 mm or more, preferably in the range of 1 mm to 100 mm, more preferably in the range of 10 mm to 70 mm, most preferably in the range of 20 mm to 50 mm, measured in the longitudinal direction.

[0090] In another example, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and an aspiration lumen extending along a longitudinal axis. The distal tip has a proximal end incorporated into the distal end of the tubular catheter body and a central passage in longitudinal communication with the aspiration lumen of the tubular catheter body. The distal tip is adapted to expand from a delivery configuration to a first radially expanded configuration in response to a radially outward expansion force applied to the distal tip, wherein the first radially expanded configuration is in the range of 1.1 to 2 times the delivery configuration, and wherein the distal tip comprises one or more expandable membranes and an expandable stent, wherein the expandable stent comprises one or more expandable rings spaced apart along the longitudinal axis with a gap between the expandable rings, and wherein the expandable rings comprise structural elements comprising struts joined by crowns. The one or more rings are composed of a malleable metal or metal alloy (or alternatively formed of a shape memory metal alloy) configured to plastically deform in response to a radially outward expansion force applied from inside the distal end or distal tip to expand the stent or other expandable support structure circumferentially. In a specific example, the expandable stent consists of one, two, or three expandable rings. In another specific example, the expandable stent consists of one expandable ring.

[0091] In some cases, the distal tip including the expandable stent or other expandable support structure has a minimum bend radius of 5 mm, preferably 3 mm, more preferably 2 mm, without deformation and / or kinking in its delivery configuration or radially collapsed configuration, and preferably a minimum bend radius of 10 mm, preferably 6 mm, more preferably 2 mm, without deformation and / or kinking in its radially expanded configuration. The minimum bend radius can be determined by bending the distal tip around a cylinder of known radius and observing whether the distal tip deforms and / or kinks.

[0092] In some cases, the rings of the expandable stent or other expandable support structure span a length, measured in the longitudinal direction, ranging from 0.25 mm to 500 mm or more, preferably ranging from 1 mm to 100 mm, more preferably ranging from 10 mm to 70 mm, most preferably ranging from 10 mm to 40 mm.

[0093] In some cases, the expandable stent or other expandable support structure consists of 1 ring to 800 rings or more, preferably 25 rings to 650 rings or more, more preferably 50 rings to 500 rings or more, spanning one or more expandable axial segment lengths ranging from 0.2 mm to 50 cm, preferably ranging from 10 mm to 40 cm, more preferably ranging from 15 mm to 25 cm, arranged in the longitudinal direction from the distal end to the distal or proximal end of the aspiration catheter. In a preferred example, the expandable stent or other expandable support structure includes or consists of a plurality of rings per mm of axial (longitudinal) stent or other expandable support structure length, ranging from 2 rings per mm of axial (longitudinal) stent length, preferably consisting of 2.5 rings to 4 rings per mm of axial (longitudinal) stent length, and more preferably consisting of 3 rings to 4 rings per mm of axial (longitudinal) stent length.

[0094] In some cases or in some examples, the expandable support structure includes a plurality of adjacent rings with a gap between adjacent rings. In some examples, the gap between adjacent rings has a length, measured in the longitudinal / axial direction, ranging from 0.0125 mm to 0.25 mm, preferably 0.025 mm to 0.2 mm, more preferably 0.05 mm to 0.17 mm.

[0095] In some cases, the axial length of the gap between adjacent rings (i.e., the length of the gap measured in the axial direction) can be constant. In other cases, the axial length of the gap between adjacent rings can be variable. For example, the length (or axial length) of the gap between at least some adjacent rings ranges from 0.05 mm to 0.2 mm. In another preferred example, a plurality of adjacent rings span at least a 3 mm segment along the length of the expandable structure, more preferably at least a 7 mm segment along the length of the expandable stent, more preferably at least a 20 mm segment along the length of the expandable stent, wherein the length of the gap between adjacent rings ranges from 0.05 mm to 0.2 mm.

[0096] In some cases, the distal tip has at least 2 rings per mm of axial length, preferably at least 3 rings per mm of axial length, typically 1.5 to 5 rings per mm of axial length, and more typically 2 to 5 rings per mm of axial length, or more typically 3 to 4 rings per mm of axial length.

[0097] In some preferred cases, at least some of the adjacent rings are end-to-end continuously linked in a helical arrangement. In other cases, at least some of the adjacent rings are planar, arranged in parallel, and linked by axial links or other means such as attachment points, and are not end-to-end continuously linked. The parallel planes can be perpendicular or tilted relative to the longitudinal axis of the distal tip in its delivery configuration. The adjacent rings can be linked preferably by a single axial link or attachment point, or by no more than two axial links or attachment points. In some preferred cases, at least some of the adjacent rings of the expandable stent are end-to-end continuously linked in a helical pattern or arrangement. In other cases, at least some of the adjacent rings of the expandable stent are planar, arranged in parallel, and linked by axial links or attachment points that link or connect structural elements on adjacent rings. In this other case, the stent adjacent rings are not end-to-end continuously linked in a helical arrangement. The parallel planes can be perpendicular or tilted relative to the longitudinal axis of the distal tip in its delivery configuration. The adjacent rings can be linked preferably by a single axial link or attachment point, or by no more than two axial links or attachment points.

[0098] In other cases, at least some of the adjacent rings of the expandable stent are planar, arranged in parallel, and not connected to each other. (Not by links, attachment points, or end-to-end linked in a helical arrangement). The parallel planes can be perpendicular or tilted relative to the longitudinal axis of the distal tip in its delivery configuration. In this case, at least some of the adjacent rings are covered by one or more membranes that adhere to the unconnected adjacent rings, hold them together, and allow the at least some of the adjacent rings to expand from the delivery configuration to the expanded configuration. This allows for enhanced delivery capability of the distal tip to navigate through the vascular anatomy in the delivery configuration, and allows the at least some of the rings to expand from the delivery configuration to the expanded configuration, and resist collapse of the distal tip from the expanded configuration when a vacuum is applied at the proximal end of the aspiration lumen and the clot engages (or embolically plugs) the distal end of the distal tip.

[0099] In some cases, at least some of the adjacent rings in the helical and / or planar arrangement can include a non-linear portion.

[0100] In some cases, all of the adjacent rings in the helical and / or planar arrangement are free of non-linear portions.

[0101] In some cases, the thickness of at least some of the adjacent rings ranges from 0.03 mm to 0.3 mm, preferably ranges from 0.05 mm to 0.25 mm, more preferably ranges from 0.05 mm to 0.2 mm.

[0102] In some cases, the forgeable metal includes a metal or metal alloy selected from the group consisting of: cobalt-chrome, such as L-605, MP35N, Elgiloy 6B, ASTM F1537 / F799 Alloy 1, ASTM F1537 / F799 Alloy 2; stainless steel, such as 316, 316L, 316LS, 316LVM, 304, 304V, 304L, 304LV, 304LVM, 410, 410L, 410S, 420, 420L, and 420S; tantalum; niobium; tungsten; molybdenum; molybdenum alloys, such as molybdenum-rhenium, where the sum of molybdenum and rhenium is 90% to 100%, and the molybdenum-rhenium can include one or more metals such as: boron, calcium, chromium, cobalt, copper, gold, iron, lead, magnesium, manganese, mercury, nickel, niobium, platinum, rare earth metals, silicon, silver, sulfur, tantalum, tin, titanium, tungsten, yttrium, zinc, and zirconium; platinum; platinum alloys, such as platinum-iridium, platinum-chromium, platinum-cobalt-chromium; magnesium; magnesium alloys, such as Mg-3Al-lZ, Mg-Zn-Se, and Mg-Zn-Cu; zinc, and the like, or other.

[0103] In some cases, the stent or other expandable support structure includes a metal or metal alloy selected from the group consisting of nitinol, super-elastic nitinol, and the like, or other. In such cases, the expandable support structure is constrained in a delivery configuration, and released from the constraint to expand the stent to an expanded configuration.

[0104] In some cases, the expandable membrane includes one or more elastic membranes, and / or non-elastic but stretchable membranes, and / or one or more plastically deformable membranes, where the membranes can include one or more membranes including a polymer, an elastomer, or other material as previously listed.

[0105] In some cases, the elastic membrane can have isotropic properties. In other cases, the elastic membrane can have anisotropic properties. For example, the elasticity of the membrane in a circumferential direction can be higher than in an axial direction.

[0106] In some cases, the expandable membrane can include an elastic membrane, a non-elastic but stretchable membrane, or other type of expandable material. Suitable materials are shown as previously listed.

[0107] In some cases, the non-elastic membrane can be configured to stretch or plastically deform as the stent or other expandable support structure expands. In other cases, the non-elastic membrane can be configured to unfold as the stent or other expandable support structure expands.

[0108] In some cases, the distal tip can be formed by heat shrinking a tubular membrane over an expandable stent or other expandable support structure. In other cases, the distal tip can be formed by laminating an expandable stent or other expandable support structure between layers of a tubular membrane. For example, the layers can be adhered to one another such that there is a seal between the layers. In a preferred example, one or more expandable membrane flows over and adheres to at least some of the side surfaces of the structural elements of the expandable support structure sufficiently to provide a unified system (integrated system) in the delivery configuration and when expanded to the expanded configuration. In yet another example, the polymer layers on the outer surface of the stent and the inner surface of the stent can be adhered to one another and / or to the structural elements of the stent such that there is a seal between the layers and / or adhere to the structural elements to provide a unified integrated system that can expand from the delivery configuration to the expanded configuration. In a preferred example, the structural elements of the stent cannot move or expand freely without moving or expanding the expandable membrane adjacent to the structural elements. In yet another example, the layers on the outer surface of the stent and the inner surface of the stent can be coupled, attached, and / or adhered to one another substantially eliminating the gaps between the structural elements of the stent (or filling the gaps) and providing a unified expandable stent that can expand from the delivery configuration to the expanded configuration. In yet another example, one or more layers on the outer surface of the stent or one or more layers on the inner surface of the stent are fused or laminated to the structural elements of the stent at least partially eliminating the gaps between the structural elements and adhering to the structural elements providing the stent with the ability to expand from the delivery configuration to the expanded configuration as a unified system.

[0109] In some cases, the tubular membrane can be composed of at least two membrane segments, where the at least two membrane segments can include a single type of material, at least two types of materials, or three or more different types of materials.

[0110] In some cases, the at least two membrane segments can cover at least one outer surface of the expandable stent or other expandable support structure. In some cases, the at least two membrane segments can cover at least one inner surface of the expandable stent or other expandable support structure. In some cases, the at least two membrane segments cover both the inner and outer surfaces of the expandable stent or other expandable support structure, where at least one of the at least two membrane segments covers the outer surface of the stent and at least a second membrane segment covers the inner surface of the expandable stent.

[0111] In some cases, the tubular catheter body can be reinforced over at least a portion of its length by a catheter stent or other support structure, typically a flexible but non-expandable support structure. In specific examples, the catheter stent or other support structure can be formed continuously with the expandable stent or other expandable support structure. For example, the catheter and support stent can be patterned from the same tube or bend line. In other cases, the catheter stent and expandable stent can be formed from one or more bend lines that each span at least a portion of the typically non-expandable catheter stent and the expandable distal tip stent.

[0112] In some cases, the expandable stent can further include a plurality of overhanging support elements or other support elements, each support element having a base end and a free end, wherein the base end is attached to one of the radially expandable rings and the free end extends toward or into an adjacent axial and / or circumferential gap.

[0113] In some cases, at least some of the plurality of rings can include struts joined by bends (crowns), and the base end of at least some of the plurality of support elements is attached to a strut, and the base end of at least some of the plurality of support elements is attached to a bend (crown).

[0114] In some cases, the base end of at least some of the plurality of support elements can be attached to an inner surface of a ring, namely an inner bend of a crown.

[0115] In some cases, the base end of at least some of the plurality of support elements can be attached to an outer surface of a ring, namely an outer surface of a crown or an apex of an outer surface of a crown.

[0116] In some cases, at least some of the plurality of support elements have a constant width over a distal portion thereof. In some cases, at least some of the plurality of support elements have a constant width over an entire length thereof.

[0117] In some cases, at least some of the plurality of support elements have a variable width over a distal portion thereof.

[0118] In some cases, at least some of the plurality of support elements have a distal tip that extends into an adjacent circumferential gap, axial gap, or other gap.

[0119] In some cases, at least some of the plurality of support elements have a distal tip that terminates flush with a bend joining a strut.

[0120] In some cases, at least some of the plurality of support elements have a distal tip that is recessed between adjacent bends joining struts.

[0121] In a fifth aspect, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. The distal end comprises an expandable distal tip and a central passageway, wherein the central passageway is typically longitudinally continuous with the lumen of the tubular catheter body. The distal tip is adapted to expand from a radially collapsed or delivery configuration to a radially expanded configuration in response to a radially outward expanding force applied inside the distal tip, and the distal tip comprises a tubular membrane covering an expandable stent or an expandable support stent (e.g., adhered to, attached to, bonded to, or laminated with the expandable stent or the expandable support stent). The expandable stent or the expandable support stent comprises a plurality of rings spaced apart along the longitudinal axis with gaps (extending between the rings) between the plurality of rings, and at least some of the rings comprise circumferentially adjacent cells having a curvature (such as a crown) configured to straighten (such as expand) in response to the radially outward expanding force applied inside the distal tip to allow the rings to expand from the radially collapsed or delivery configuration to the radially expanded configuration, wherein the radially expanded configuration is larger than the collapsed configuration. In some preferred cases, at least some adjacent rings of the expandable stent or the expandable support stent are continuously linked end-to-end in a helical arrangement, typically without an axial link or attachment point. In preferred cases, at least some adjacent rings of the expandable stent or the expandable support stent have a fixed cell amplitude within each ring. In other cases, at least some adjacent rings of the expandable stent or the expandable support stent have a fixed cell amplitude within at least some of the rings. In rare cases, at least some adjacent rings of the expandable stent or the expandable support stent can have a variable cell amplitude within each ring or within at least some of the rings. In such cases, the pitch angle of at least some adjacent rings in the patterned or delivery configuration relative to the longitudinal axis of the stent or the distal tip ranges from 70° to 89.9° or 75° to 89.9°, typically from 80° to 89.9°, more typically from 84° to 89.75°, and often from 85° to 88.5°. As used herein and as illustrated in the drawings, the "pitch angle" will be the acute angle (between 0° and 90°) formed by the ring relative to the longitudinal axis of the distal tip of the aspiration catheter, rather than the obtuse angle (between 90° and 180°). In some other cases, at least some adjacent rings of the expandable stent or the expandable support stent are planar, arranged in parallel, and linked by one axial link or attachment point linking structural elements on adjacent rings. In rare cases, at least some adjacent rings are linked by no more than two axial links, no more than two attachment points linking structural elements on adjacent rings, or no more than one link and no more than one attachment point. The parallel planes can be perpendicular or tilted relative to the longitudinal axis of the distal tip in their delivery configuration.

[0122] In some cases, the cells can be arranged in any one or more of a box pattern, a diamond pattern, a sine pattern, a serpentine pattern, an omega wave pattern, a zigzag pattern, a square wave pattern, a rectangular wave pattern, a wave pattern, a trough pattern, an open cell pattern, a closed cell pattern, a combination of open and closed cell patterns, a combination of patterns, or other patterns, etc.

[0123] In some cases, adjacent and / or non-adjacent rings have in-phase or out-of-phase crowns.

[0124] In some cases, the cells can include struts joined by bends.

[0125] In some cases, in the delivery configuration or in the patterned configuration, at least some of the expandable cells on one or more rings of the expandable stent, or at least some of the expandable cells on at least some rings of the expandable stent, or at least some of the expandable cells on every ring of the expandable stent, or at least some circumferentially adjacent cells of at least some rings of the expandable stent, or at least some circumferentially adjacent cells on at least some adjacent rings of the expandable stent, or substantially all of the cells on the expandable stent, or all of the cells along the length of the stent (where the length is less than the length of the stent), or all of the cells along the length of the stent, can have a cell period (distance between like points on circumferentially adjacent cells measured in the collapsed configuration) ranging from 0.03 mm to 1.3 mm, preferably 0.04 mm to 0.8 mm, more preferably 0.05 mm to 0.5 mm, most preferably 0.05 mm to 0.15 mm. Having a small cell period enhances the roundness of a ring, the roundness of multiple rings, or the roundness of the expandable stent, thereby enhancing the ability of the expandable stent to pass through the vasculature in the delivery configuration without deforming or kinking, and the enhanced roundness resists collapse of the expandable distal tip when expanding to the expanded configuration and while the distal tip is engaged with (or clogged by) a clot while vacuum is applied at the proximal end of the aspiration catheter. Moreover, having a small cell period increases (or enhances) the aspiration area within a ring, within multiple rings, or within the expandable stent or expandable distal tip.

[0126] In some cases, circumferentially adjacent cells on at least one ring or at least some rings of the expandable stent (or at least some circumferentially adjacent cells on the same ring, or at least some circumferentially adjacent cells on at least some adjacent rings), or at least one ring, at least some rings, or all rings of the expandable stent, in the delivery configuration or the patterned configuration can have an inter-peak amplitude (ring width in the longitudinal / axial direction (axial width of the ring)) ranging from 0.05 mm to 1.2 mm, preferably from 0.05 mm to 0.8 mm, more preferably from 0.15 mm to 0.5 mm, most preferably from 0.15 mm to 0.35 mm. In a preferred example, the cell amplitude of each cell on the same ring has the same length (i.e., is fixed or constant) in the delivery configuration or the patterned configuration. In another preferred example, at least some adjacent rings have the same length of cell or ring amplitude on the at least some rings. Having a small amplitude enhances the flexibility of the expandable stent, thereby enhancing the passage of the expandable stent (or the expandable distal tip) when the aspiration catheter is advanced into the vasculature. Moreover, having a small amplitude further enhances the expandable stent in the expanded configuration and resists collapse of the stent or the expandable membrane coupled to the stent when a vacuum is applied at the proximal end of the aspiration catheter and the distal tip is engaged with a clot.

[0127] In some cases, circumferentially adjacent cells (or at least some circumferentially adjacent cells, or at least some circumferentially adjacent cells on at least some adjacent rings, or all cells on the expandable stent, or at least some cells within a ring, or all cells within at least some rings, or all cells within rings of the expandable stent) can have a cell period to (peak-to-peak axial width of the ring) amplitude ratio in the range of 0.3:1 to 1.6:1 as measured in the delivery configuration or in the patterned configuration for all examples. In one example, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 0.3:1 to 1.6:1. In other examples, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 0.4:1 to 1.5:1. In yet another example, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 0.5:1 to 1.3:1. In yet another example, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 0.6:1 to 1.2:1. In yet another example, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 1:1 to 1.6:1. In yet another example, the cell period to (peak-to-peak axial width of the ring) amplitude ratio is in the range of 0.3:1 to 1.2:1. In some other examples, circumferentially adjacent cells (or at least some cells on a ring or rings or at least some rings, or all cells on at least one ring or at least some rings or at least some rings of the expandable stent) can have a cell period and (peak-to-peak axial width of the ring) amplitude that are each 0.25 mm ± 0.2 mm in length, preferably each 0.25 mm ± 0.15 mm in length, and more preferably each 0.25 mm ± 0.1 mm in length as measured in the delivery configuration (or as measured in the patterned configuration). Having the length of the cell period and the amplitude of at least some cells within a ring or rings or at least some rings within ± 0.2 mm of each other enhances the symmetry and / or compactness of the rings of the expandable stent against deformation and / or kinking when the expandable stent is passed through the vasculature in the delivery configuration.

[0128] In some cases, each ring (or at least some rings) can include 2 cells to 15 cells per mm of circumference, preferably each ring (or at least some rings) can include 3 cells to 10 cells per mm of circumference, and most preferably each ring (or at least some rings) can include 4 cells to 9 cells per mm of circumference.

[0129] In some cases, at least some of the loops in a stent or other expandable support structure can have a ratio of (1) the number of bends to (2) the circumference, where the ratio is typically in the range of 0.8 per mm to 15 per mm, preferably in the range of 1 per mm to 15 per mm, more preferably in the range of 2 per mm to 15 per mm, more preferably in the range of 3 per mm to 15 per mm, and most preferably in the range of 4 per mm to 12 per mm. Support structures with overhanging support elements or other support elements will typically have fewer bends per unit length of loop circumference.

[0130] The ratio of (1) the number of bends to (2) the circumference can be constant or variable over at least some of the loops, over all or a portion of a stent or other expandable support structure.

[0131] In some cases, a loop can span a segment of the distal tip having a length in the range of 0.5 mm to 500 mm or more, typically 10 mm to 100 mm, more typically 10 mm to 40 mm, measured in the longitudinal direction.

[0132] In some cases, a loop can span a segment of the distal tip having a length in the range of 0.5 mm to 500 mm or more, typically 10 mm to 100 mm, more typically 10 mm to 40 mm, measured in the longitudinal direction. In some cases, a stent is comprised of one expandable loop spanning a length in the distal tip in the range of 0.1 mm to 0.5 mm, typically 0.15 mm to 0.35 mm, more typically 0.15 mm to 0.3 mm, measured in the longitudinal direction.

[0133] In some cases, a distal tip can have 1 to 10 loops per mm of length of the distal tip, typically 2 to 8 loops per mm of length of the distal tip, more typically 3 to 5 loops per mm of length of the distal tip.

[0134] In preferred examples, the rings of the expandable support structure include a curved portion (e.g., a crown) and a strut, where the curved portion has an arc length measured along its arc and the strut has an axial length, where the ratio of the arc length of the curved portion or crown to the axial length of the strut ranges from 0.2: 1 to 2: 1, preferably from 0.5: 1 to 1.5: 1, and more preferably from 0.75: 1 to 1.25: 1. In specific preferred examples, the arc length of the crown and the axial length of the strut connected to the crown each range from 0.05 mm to 0.25 mm, preferably from 0.075 mm to 0.225 mm, and more preferably from 0.1 mm to 0.2 mm, preferably about 0.15 mm, or preferably 0.15 ± 0.05 mm, for example 0.15 ± 0.05 mm.

[0135] In some cases, at least some of the adjacent rings in the expandable distal tip can be formed from tubes or curved wires and are joined end-to-end in a helical arrangement. For example, at least some of the adjacent rings can be joined at an absolute pitch angle relative to the longitudinal axis ranging from 70° to 89.9°, or 75° to 89.9°, often 80° to 89.9°, more often 84° to 89.75°, and frequently 85° to 88.5° (as in the patterned or delivered configuration). The absolute pitch angle can be constant or variable along at least some of the rings, or along the length of the expandable stent (or along the length of the expandable stent where the length is shorter than the length of the stent, or along other expandable support structures) or other expandable support structures. The absolute pitch angle of at least some of the adjacent rings can be constant or variable along the length of the expandable stent or other expandable support structures. The pitch angle is typically measured in the patterned configuration. Alternatively, the pitch angle described above can be measured in the delivered configuration. In preferred cases, at least some of the adjacent rings have no links or attachment points between adjacent rings. In other preferred cases, at least some of the adjacent rings have a fixed cell amplitude within each ring or within at least adjacent rings. In rare cases, at least some of the adjacent rings can have attachment points or links connecting adjacent rings. In other rare cases, at least some of the adjacent rings can have a variable cell amplitude or a variable ring amplitude within each ring or within adjacent rings.

[0136] In other cases, at least some of the adjacent rings can be arranged as separate parallel planes and joined by axial links or by other means such as crowns on adjacent rings that are fused / welded or otherwise joined together (attachment points). The separate parallel planes can be oriented perpendicularly or at an angle relative to the longitudinal axis of the stent or other expandable support structure when straightened. In some cases, the separate adjacent rings are not joined together by links or other means, but are held together by one or more expandable membranes that contain, cover, and / or embed the separate rings.

[0137] In some cases, at least some of the cells can comprise a malleable metal or metal alloy that is configured to plastically deform. The malleable metal can comprise a metal or metal alloy previously described in this application.

[0138] In some cases, the radially contracted configuration of the stent or other expandable support structure and / or distal tip can have a maximum diameter in the range of 0.5 mm to 30 mm, typically 1.3 mm to 5.5 mm, and the radially expanded configuration can have a minimum diameter in the range of 1 mm to 40 mm, typically 2 mm to 5.5 mm.

[0139] In some cases, the distal tip can be configured to expand from an initial cylindrical shape to an enlarged cylindrical configuration in response to a radially outward expanding force applied within the distal tip.

[0140] In some cases, the distal tip can be configured to expand from an initial cylindrical shape to an enlarged conical configuration in response to a radially outward expanding force applied within (or from inside) the distal tip.

[0141] In some cases, circumferentially adjacent cells of at least some of the rings in the distal tip can have a circular, elliptical, oblong, flat, or substantially flat outer surface and / or inner surface that define a “facet” in a polygonal structure. In those cases, the ring can have a first radius from an axial centerline of the ring to a circumferential center of each facet and a second radius from the axial centerline of the ring to a circumferential edge of each facet, wherein in the expanded configuration, the length of the first radius is 97% to 99.9%, preferably 98% to 99.7%, more preferably 98.5% to 99.5%, and most preferably 99% to 99.5% of the length of the second radius. This provides one or more of the following to the expandable distal tip: an enlarged inner lumen configuration (or maximum inner lumen configuration), enhanced aspiration lumen area, maximized aspiration lumen area in the expanded configuration, resistance to collapse in the expanded configuration under vacuum when the distal tip is engaged with (or clogged or blocked by) a clot or other material, enhanced delivery capability of the aspiration catheter distal tip, and enhanced resistance to deformation or kinking of the expandable distal tip in the delivery configuration when passing through the vasculature. In a preferred case, the expandable tip in the expanded configuration has a “roundness” in the range of 97% to 99.9%, preferably in the range of 98% to 99.5%, and more preferably in the range of 98.5% to 99.5% (as defined below with reference to FIG. 16). In another preferred case, the roundness of the expandable tip in the expanded configuration is greater than 97%, preferably greater than 98%, more preferably greater than 98.5%, and most preferably greater than 90%. The roundness of the expandable distal tip refers to the inner lumen configuration. Alternatively, the roundness of the expandable distal tip measures the outer perimeter of the distal tip.

[0142] In some cases, the tubular catheter body can have a length ranging from 50 cm to 200 cm from the proximal end to the distal end, the tubular catheter body can have an outer diameter ranging from 0.5 mm to 30 mm, and the tubular catheter body can have an inner lumen diameter ranging from 0.25 mm to 25 mm. In one example, the expandable distal tip has a length ranging from 0.5 mm to 50 cm. In another example, the expandable distal tip has the same length as the distal end length. In other examples, the expandable distal tip comprises substantially the entire length of the catheter tubular body. In yet another example, the expandable distal tip is comprised of an expandable stent (or expandable support stent) covered with or embedded in one or more polymeric materials, wherein the expandable stent comprises one circumferential ring comprising a plurality of struts joined by crowns, and wherein the ring resists collapse when a vacuum is applied at the proximal end of the aspiration lumen and the distal end of the distal tip is opposed or occluded by a clot. In some other cases, the expandable stent comprises 2, 3, 4, or 5 circumferential rings.

[0143] In some cases, the expandable distal tip can further comprise a plurality of support elements, wherein each support element can have a base end and a free end, and wherein the base end is attached to one of the radially expandable rings and the free end extends toward or into an adjacent gap in an axial and / or circumferential direction of the distal tip. For example, at least some of the plurality of rings can comprise struts joined by bends, and the base end of at least some of the plurality of support elements can be attached to the struts and / or the base end of at least some of the plurality of support elements can be attached to the bends.

[0144] In other cases, the base end of at least some of the plurality of support elements can be attached to an inner surface of the ring (or structural element of the ring) and / or to an outer surface of the ring (or structural element of the ring).

[0145] In some cases, at least some of the plurality of support elements can have a constant width over a distal portion thereof or along an entire length thereof. In other cases, at least some of the plurality of support elements can have a variable width over a distal portion thereof or along a length thereof. In other cases, at least some of the plurality of support elements can have a greater width at a base portion thereof and a constant width along a remaining length of the support element. In a preferred example, the width of the support element is greater than the width of an adjacent strut, crown, or ring segment. Having a greater support element width than an adjacent structural element allows the expandable stent or other expandable support structure to collapse after the stent is expanded to an expanded configuration when the stent is withdrawn into a guide catheter having a smaller inner lumen than the expanded configuration of the expandable stent.

[0146] In some cases, at least some of the plurality of support elements can have a distal tip that extends toward and / or into an adjacent circumferential and / or axial gap.

[0147] In some cases, at least some of the plurality of support elements can have a distal tip that terminates flush with an adjacent bend or crown of the link strut.

[0148] In some cases, at least some of the plurality of support elements have a distal tip that is recessed between adjacent bends of the link strut in the delivery configuration, and wherein the support element further projects toward or further into the adjacent gap.

[0149] In still other aspects, the present invention provides a method for aspirating a clot from a patient's vasculature, the method comprising positioning a distal tip of any of the aspiration catheters described herein in the patient's vasculature at a clot region. The distal tip expands to its radially expanded configuration, or expands from the delivery configuration to the radially expanded configuration, to engage a vessel wall adjacent the clot region, or to engage the clot, and a negative pressure is applied to a proximal end of a lumen in the catheter body to aspirate the clot into a central passageway of the expanded expandable support structure (aspiration lumen). The expanded configuration has a greater suction force than the delivery configuration under the same applied vacuum. The suction force in the expanded configuration is in the range of 1.1 to 10 times greater, preferably in the range of 1.5 to 6 times greater, and more preferably in the range of 1.8 to 6 times greater than the suction force of the delivery configuration.

[0150] In some cases, at least a portion of the expandable stent or other expandable support structure remains at least partially unexpanded after another portion of the expandable stent expands. The at least partially unexpanded portion can have a variety of shapes, such as a tapered shape, an elliptical shape, a rectangular shape, a flattened shape, or other shape. In some other cases, at least one segment of the expandable stent or other expandable support structure remains unexpanded after another adjacent segment of the expandable stent or other expandable support structure expands to the expanded configuration.

[0151] In still other aspects, the present invention provides a method for aspirating a clot from a patient's vasculature, the method comprising positioning a distal tip of any of the aspiration catheters described herein in the patient's vasculature at a clot region. At least a segment of the distal tip expands from the delivery configuration (collapsed configuration) to its radially expanded configuration to engage a vessel wall adjacent the clot region, or to engage the clot, and a negative pressure is applied to a proximal end of a lumen in the catheter body to aspirate the clot into a central passageway of the expanded expandable structure. In other examples, the clot is aspirated in the collapsed configuration (delivery configuration) without expanding the distal tip to the expanded configuration.

[0152] In some cases, a segment or other portion of an expandable stent or other expandable support structure remains at least partially unexpanded after expansion of another portion of the expandable stent.

[0153] In yet other aspects, the present invention provides an aspiration catheter comprising a tubular catheter body having a proximal end, a distal end, and a lumen extending along a longitudinal axis. An expandable coil comprising consecutive helical turns is disposed along the longitudinal axis, wherein the expandable coil comprises undulating bends and struts, and has gaps between the consecutive turns, wherein the consecutive turns are inclined at an acute angle of pitch relative to the longitudinal axis. A sheath is disposed about the expandable coil. In preferred examples, in a patterned or delivery configuration, the acute angle of pitch ranges from 70° to 89.9°, typically from 80° to 89.75°, and more typically from 82° to 89.75°, relative to the longitudinal axis. In preferred examples, at least some of the consecutive turns lack a link or attachment point that links the adjacent turns. In yet another preferred example, at least some adjacent turns have a fixed cell amplitude within each turn or within at least some adjacent turns.

[0154] In some cases, an expandable stent or other expandable support structure is comprised of an expandable coil, wherein the expandable coil comprises a plurality of adjacent expandable rings linked end-to-end in a helical arrangement, wherein each ring comprises a structural element comprising struts linked by a crown, and wherein the expandable coil has an acute angle of pitch ranging from 70° to 89.9°, preferably ranging from 80° to 89°, relative to a longitudinal axis, in a patterned or delivery configuration. The expandable coil is expanded from a delivery or collapsed configuration to an expanded configuration by an expandable support structure, such as a balloon catheter, that is radially expanded within the interior of the expandable coil, wherein the expandable coil is referred to as balloon-expandable.

[0155] In some cases, the expandable coil can be configured to be expanded by an expandable support structure that is radially expanded within the interior of the expandable coil. For example, the expandable coil can be balloon-expandable.

[0156] In some cases, the coil can be at least partially formed of a malleable metal or metal alloy. In some other examples, the coil can be formed of a malleable metal or metal alloy.

[0157] In some other cases, the coil can be formed of a shape memory metal or shape memory alloy, wherein the expandable distal tip is constrained in a delivery configuration and released to expand to a larger expanded configuration. Examples of shape memory alloys include nickel-titanium alloys or others.

[0158] In some cases, at least a proximal portion of the tubular catheter body can be non-expandable.

[0159] In some cases, at least a proximal portion of the tubular catheter body can be radially expandable.

[0160] In some cases, the expandable coil can be attached to a reinforcing member in the proximal segment of the catheter body.

[0161] In some cases, the expandable coil and the reinforcing member can be formed from a continuous wire or tube.

[0162] In some cases, adjacent rings can be joined in a patterned configuration or a delivery configuration at an acute angle of 70° to 89.9° relative to the longitudinal axis, preferably a range of 80° to 89.9°, more preferably a range of 85° to 89°, and most preferably a range of 86° to 89°.

[0163] In some cases, the expandable coil can be attached to, incorporated within, or coupled to a distal end of the tubular catheter body. In some other cases, the expandable coil can extend from a distal end to a proximal end of the tubular catheter body, or to a proximal end of the tubular catheter body. In some cases, the expandable coil can be attached to a proximal end of the tubular catheter body.

[0164] In some cases, the expandable coil is embedded or laminated in an expandable membrane or embedded or laminated in the tubular catheter body.

[0165] In some cases, the expandable coil can have a crimped delivery configuration and an expanded deployed configuration.

[0166] In some cases, the expandable coil can have a crimped delivery configuration and an expanded deployed configuration.

[0167] It is to be understood that all features and aspects of the devices and methods of the present application described herein can be arranged in different combinations, and that even if no specific embodiments or examples of a particular combination are provided, these features and aspects are encompassed by the claims. Features described in whole or in part in all paragraphs, examples, embodiments, figures, and other aspects set forth herein can be combined in ways not specifically described and can be part of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0168] FIGS. 1A-1D Figures illustrate exemplary stents of the endovascular prosthesis of the present application having support elements, and in the form of a bare metal stent ( FIG. 1A ), a fully covered stent graft ( FIG. 1B ), a partially covered stent graft ( FIG. 1C ), and in a radially expanded deployed configurationFIG. 1D ) is shown.

[0169] FIG. 2 is a detailed view of one end of the stent of FIGS. 1A-1D

[0170] FIG. 3 is a detailed view of one end of the stent of FIGS. 1A-1D

[0171] FIG. 4A and FIG. 4B Figure 1 illustrates an alternative stent embodiment of an endovascular prosthesis suitable for use in the present invention in the form of a bare metal stent shown in a delivery (unexpanded) and deployed (expanded) configuration having circumferential support rings in a helical arrangement without support.

[0172] FIG. 5A and FIG. 5B Figure 1 illustrates an alternative stent embodiment of an endovascular prosthesis suitable for use in the present invention in the form of a bare metal stent shown in a delivery (unexpanded) and deployed (expanded) configuration having circumferential support rings in a helical arrangement without support. FIGS. 1A-1D

[0173] FIG. 6A is a detailed view of one end of the stent of FIG. 4B

[0174] FIG. 6B is a detailed view of adjacent circumferential support rings of the expandable stent of FIG. 4B

[0175] FIG. 7A and FIG. 7B Figure 1 illustrates an alternative stent embodiment of an endovascular prosthesis suitable for use in the present invention in the form of a bare metal stent shown in a delivery (unexpanded) and deployed (expanded) configuration having circumferential support rings in a helical arrangement without support. FIG. 4A FIG. 4B

[0176] FIGS. 8A-8C Figure 1 illustrates an alternative stent embodiment of an endovascular prosthesis suitable for use in the present invention in the form of a bare metal stent shown in a delivery (unexpanded) and deployed (expanded) configuration having circumferential support rings in a helical arrangement without support.

[0177] FIG. 9 is a cross-sectional view of a support stent of the present invention embedded in a membrane in the form of a stent graft, illustrating how the cells of the support stent form a flat "facet" in the outer surface of the radially expandable stent. The roundness is defined as the ratio of the radius (r) of the facet in the membrane in the middle of the cell to the radius (R) of the cell x 100, expressed in percentage.

[0178] FIG. 10 Various features of the rings that can be used to define the structure of the stent or helical radially expandable stent of the present invention are defined.

[0179] FIGS. 11A-11C ​​​​​​​is a side view, perspective view and "unrolled" view of an expandable stent comprising a plurality of laterally oriented, axially linked (or concatenated) expandable rings.

[0180] FIG. 12 Various features that can be used to define the structure of an expandable stent comprising a plurality of laterally oriented, axially linked (or concatenated) expandable rings, such as the expandable rings shown in FIGS. 11A-11C

[0181] FIG. 13A FIG. 13B is a side view and perspective view of a stent of the present invention having radially expandable rings of omega-shaped cells arranged in a helix connected.

[0182] FIGS. 14A-14C is a detailed exemplary view illustrating different bend patterns that can be used in a single radially expandable stent ring of the present invention.

[0183] FIG. 15A FIG. 15B are "unrolled" views of a closed cell box ring pattern shown in its non-expanded and expanded configurations, respectively.

[0184] FIG. 16A FIG. 16B are "unrolled" views of a closed cell box ring pattern shown in its non-expanded and expanded configurations, respectively, the closed cell box ring pattern further comprising in the non-expanded configuration "overhanging" support elements recessed between circumferentially adjacent box elements.

[0185] FIG. 17A FIG. 17B are "unrolled" views of a portion of an alternative closed cell box ring pattern shown in its non-expanded and expanded configurations, respectively.

[0186] FIG. 18 are "unrolled" views of a portion of an alternative closed cell box ring pattern similar to the closed cell box ring pattern shown in FIG. 17A FIG. 17B

[0187] FIG. 19 is a "unrolled" view of a portion of an alternative closed cell box ring pattern in its non-expanded configuration.

[0188] FIG. 20A FIG. 20B are detailed views of a single cell of a closed cell box ring taken along the 20-20 line in FIG. 19

[0189] FIGS. 21A-21C ​​​​​​​​​An exemplary method of embedding a radially expandable support stent into a polymer membrane to form a vascular prosthesis according to the principles of the present application is illustrated.

[0190] FIG. 22 A cross-sectional view of a region of the wall of a vascular prosthesis made by the method of FIGS. 21A-21C is illustrated in a radially expanded configuration.

[0191] FIG. 23A An "unfolded" view example of a support stent or other expandable support structure having circumferential support rings in a helical arrangement constructed according to the principles of the present application.

[0192] FIG. 23B A detailed view of adjacent circumferential support rings of the expandable distal tip of the support stent of FIG. 23A is illustrated.

[0193] FIG. 23C An image of the support cell space of the support stent of FIG. 23A incorporating a polymer tubular envelope (one or more membranes) in an unexpanded configuration (as in a delivery configuration).

[0194] FIG. 23D An image of the support stent and polymer tubular envelope (one or more membranes) of FIG. 23C is illustrated after the integrated membrane / expandable stent is radially expanded from a delivery configuration to an expanded configuration by a balloon.

[0195] FIG. 24A An "unfolded" view of another example of a support stent having circumferential support rings in a helical arrangement constructed according to the principles of the present application.

[0196] FIG. 24B A detailed view of adjacent circumferential support rings of the expandable distal tip of the support stent of FIG. 24A is illustrated.

[0197] FIG. 25A An "unfolded" view of another example of a support stent having circumferential support rings in a helical arrangement constructed according to the principles of the present application.

[0198] FIG. 25B A detailed view of adjacent circumferential support rings of the expandable distal tip of the support stent of FIG. 25A is illustrated.

[0199] FIGS. 26A-26AP Various alternative examples of the geometry of the support elements, stent design, and connection locations and shapes of the present application are illustrated.

[0200] FIG. 27is a "flattened" view of another example of a support scaffold constructed according to the principles of the present invention, having adjacently linked circumferential support rings of varying numbers of crowns, gap widths, unit periods, frequencies of unit amplitudes, and varying examples of construction of the support elements of the circumferential support rings.

[0201] FIG. 28 is a "flattened" view of an alternative example of a support scaffold constructed according to the principles of the present invention, having circumferential support rings of helical arrangements without support elements.

[0202] FIG. 29 is a detailed view of the expandable distal tip of the support scaffold of FIG. 28 .

[0203] FIG. 30 illustrates an alternative example of a support scaffold of the present invention, having discrete support pads (or islands) located between the struts of a serpentine support ring.

[0204] FIG. 31A and FIG. 31B illustrate example helical support structures comprising two and three nested continuous helical rings, respectively.

[0205] FIG. 32 and FIG. 33 illustrate how the "pitch angle" described herein can be determined as an acute angle.

[0206] FIG. 34A and FIG. 34B are side and "flattened" views of an expandable scaffold comprising a plurality of parallel, axially linked (or joined) expandable rings that are tilted relative to the longitudinal axis of the scaffold.

[0207] FIG. 35 is a "flattened" view of an expandable scaffold having segments with in- phase and out-of-phase aligned units.

[0208] FIG. 36 is a "flattened" view of an expandable scaffold comprising a plurality of rings with gaps of varying lengths between the plurality of rings.

[0209] FIG. 37A is a "flattened" view of an expandable scaffold comprising a plurality of rings arranged in a helical pattern with gaps between the plurality of rings.

[0210] FIG. 37B is a detailed example view of the rings of FIG. 37A , showing that each ring has a serpentine pattern.

[0211] FIGS. 37C-37E is a detailed example view of the rings of FIG. 37Aa rotated side view of the expandable stent of

[0212] FIG. 38A is an "unfolded" view of an expandable stent comprising a plurality of rings arranged in a helical pattern with gaps between the plurality of rings, wherein the individual rings have a first curved shape in the unfolded pattern.

[0213] FIG. 38B is a detailed view of the rings of FIG. 38A

[0214] FIGS. 38C-38E is a rotated side view of the expandable stent of FIG. 38A

[0215] is an "unfolded" view of an expandable stent comprising a plurality of rings arranged in a helical pattern with gaps between the plurality of rings, wherein the individual rings have a second curved shape in the unfolded pattern. FIG. 39A

[0216] is a detailed exemplary view of the rings of FIG. 39B FIG. 39A is a rotated side view of the expandable stent of

[0217] FIGS. 39C-39E FIG. 39A is an "unfolded" view of a ring pattern comprising S-shaped expandable elements linked by non-expandable circumferential links prior to expansion.

[0218] FIG. 40 is an "unfolded" view of a ring pattern comprising S-shaped expandable elements linked by non-expandable circumferential links prior to expansion.

[0219] FIG. 41 is an "unfolded" view of a ring pattern comprising curved lines with integrated overhanging support elements.

[0220] FIGS. 42A-42C Delivery of a balloon expandable vascular prosthesis according to the principles of the present invention is illustrated.

[0221] FIGS. 43A-43C Delivery of a self-expanding vascular prosthesis according to the principles of the present invention is illustrated. DETAILED DESCRIPTION

[0222] Referring now to FIGS. 1A-1D A first exemplary stent-like vascular prosthesis 10 constructed according to the principles of the present invention comprises or consists of a support stent 12 comprising a plurality of radially expandable circumferential support rings 14. The rings 14 comprise U-shaped curved structures or cell structures comprising struts 16 linked by crowns 18 with support elements 20 between the struts, as FIG. 2 and FIG. 3 ​​​As shown, adjacent rings 14 are connected end-to-end in a spiral pattern. The stent is typically constructed as a metal stent for balloon expansion, such as the malleable metal described elsewhere in this document. FIG. 1A As shown, the support 12 has 15 crowns on each side of each ring (spiral turn), but this number can vary.

[0223] In the second exemplary embodiment, as FIG. 1B As shown, the vascular prosthesis 30 includes FIG. 1A The stent 12 is embedded in or covered by the membrane 32 to form a stent graft. In some embodiments, the membrane 32 may be non-porous and may be configured to prevent blood flow through it. Such a non-porous membrane would be useful, for example, in peripheral vascular systems where complete isolation of an aneurysm is required or where the stent graft is deployed for bypass or similar purposes.

[0224] Conversely, when used in the cerebral vascular system, it is generally preferred that the membrane be constructed to allow controlled blood flow into the aneurysm to promote clot formation and close the aneurysm sac. In this case, the membrane may be porous, perforated, slotted, mesh-like, or otherwise constructed to provide controlled blood flow through it.

[0225] In the third exemplary embodiment, such as FIG. 1C As shown, the vascular prosthesis 40 includes FIG. 1A The stent 12 is embedded in or covered by the membrane 42 to form a stent graft. Unlike the membrane 32, which covers the entire length of the supporting stent 12 and the stent graft 30, the membrane 42 only covers the central portion 44 of the stent 12, leaving the distal end 46 uncovered. In this way, the covered central portion 44 can be positioned to cover the neck of the target aneurysm, while the uncovered distal end 46 can be extended and firmly anchored to the vessel wall away from the neck of the aneurysm.

[0226] FIG. 1D A stent 12 is shown for implantation of a vascular prosthesis 10 in its radially extended configuration. Typically (but not necessarily), for example, in... FIGS. 1A-1D In the “unfolded” pattern shown, the support bracket 12 will be laser-cut from a metal tube.

[0227] like FIG. 2 As best shown, the distal end 46 of the stent 20 includes a distal ring 26 having a bifurcation 28 that provides a transition from the helical orientation of the ring 20 to the “square” distal side of the distal ring 26. This “square” configuration eliminates the free distal end of the ring that would be exposed to the lumen of the vascular system as the vascular prosthesis is advanced through the vascular system.

[0228] like FIG. 3As best shown, the support elements 20 of the stent 12 are positioned between pairs of adjacent struts 16 and have base ends 22 attached to the inner radius of the crown 218. The unattached ends 24 of each support element 22 are recessed into the space between adjacent struts 16, but otherwise occupy most or all of the space between adjacent struts prior to ring expansion.

[0229] FIG. 4A and FIG. 4B An alternative embodiment of a vascular prosthesis 50 is illustrated, which includes or consists of a support stent 52 that includes a plurality of radially expandable circumferential support rings 54. The rings 44 include a U-shaped or unitary structure that includes struts joined by crowns, but lack the support element type described previously, in which adjacent rings 54 are connected end-to-end in a helical pattern, and the stent is generally a metallic stent configured for balloon expansion, e.g., of malleable metal as described elsewhere herein. FIG. 4A The stent 52 is shown in its radially collapsed delivery configuration in FIG. 4B The stent 52 is shown in its radially expanded deployed configuration.

[0230] As FIG. 5A As shown in FIG. 5B , the distal tips 86 of most or all of the overhanging support elements 84 will remain recessed within the axial width of the ring 72 (as shown by the line 88) until the stent 70 is radially expanded. While it is generally preferred that the support elements 84 remain recessed, in some cases the distal tips 86' of the overhanging support elements 84' can protrude into the gap region beyond the line 88, as shown in

[0231] As FIG. 6A and FIG. 6B An alternative support stent 90 suitable for use in the vascular prostheses of the present invention includes a plurality of radially expandable helically arranged support rings 92 without support elements, as shown in FIG. 4A and FIG. 4BThe stent pattern shown in FIG. 1 is similar. To enhance roundness and crush resistance, the support ring 92 has a pattern that inherently provides enhanced support to the attached expandable membrane when used in an expandable stent graft. More specifically, the support ring comprises a serpentine or zigzag ring having a width W ranging from 0.1 mm to 1 mm, preferably 0.3 mm to 0.4 mm; a gap G between adjacent rings ranging from 0 mm to 1 mm, preferably 0.05 mm to 0.4 mm; crowns arranged along an axis separated by a spacing CS ranging from 0.1 mm to 1 mm, preferably 0. mm to 0.4 mm; and struts diverging from the crowns at an angle a ranging from 0° to 90°, preferably 20° to 40° prior to expansion.

[0232] The pitch angle is an important feature of the helically arranged stent rings of the present invention. FIG. 7A and FIG. 7B illustrates how the "pitch angle" of a helical stent (such as FIG. 6A and FIG. 6B illustrated in FIG. 1 can be measured. FIG. 7A illustrates the "unfolded" pattern of an exemplary helical stent 100 in its crimped or pre-expanded configuration, while FIG. 7B illustrates the "unfolded" pattern of the same helical stent 100' in its radially expanded configuration. The pitch angle of the pre-expanded stent 100 is measured between a line LI along the longitudinal axis of the stent and a line L2 drawn parallel to the rings 102 in the stent. The pitch angle al of the stent 100 in the pre-expanded or delivery configuration is typically 70° to 89.9° or more typically 80° to 89.9°, preferably 84° to 89.9°, and more preferably 85° to 89° degrees, and most preferably 86° to 88°. The pitch angle a2 will be greater than the pitch angle al for any given stent, as the pitch angle increases as the stent is radially expanded, approaching 90° when the stent is fully expanded.

[0233] FIGS. 8A-8C illustrates a helically arranged support stent with serpentine rings with different pitch angles. FIG. 8A The pitch angle of the support stent 110 shown in FIG. 1 in its pre-expanded configuration is 87°. The pitch angle of the support stent 112 shown in FIG. 2 in its pre-expanded configuration is 86°. FIG. 8B The pitch angle of the support stent 112 shown in FIG. 2 in its pre-expanded configuration is 86°. The pitch angle of the support stent 114 shown in FIG. 3 in its pre-expanded configuration is 85°. FIG. 8C The pitch angle of the support stent 114 shown in FIG. 3 in its pre-expanded configuration is 85°.

[0234] FIG. 9The faceted outer surface of a radially expandable vascular prosthesis comprising a membrane supported by an expandable stent of the present invention is illustrated as approximating a circular outer edge (achieving enhanced "circularity"). A cross-sectional view of an exemplary radially expandable distal tip region 120 is shown in a pre-expanded configuration (120) and a radially expanded configuration (120'). The circumferential expansion ring 122 is embedded in the polymer membrane 124 such that the outer surface of the radially expandable outer surface forms a number of relatively flat facets 126 between the struts 348 of the stent 342.

[0235] In its pre-expanded configuration 1200 (e.g., 50% or less, often 100% or less, sometimes 200% or less radial expansion), the radially expandable vascular prosthesis has a first radius Rl from the axial centerline C of the ring to the circumferential center of each strut 128 and a second radius rl from the axial centerline C of the ring to the circumferential edge of each facet 126, and wherein the length of the first radius is 75% to 99%, preferably 97% to 99%, often 98% to 99%, more typically 98.5% of the length of the second radius. The circularity in the expanded configuration is preferably greater than 97%, more preferably greater than 98%, and most preferably greater than 98.5%. FIG. 9

[0236] Still referring to FIG. 9 In its expanded configuration 120' (e.g., 50% or less, often 100% or less, sometimes 200% or less radial expansion), the radially expandable vascular prosthesis has a first radius Rl from the axial centerline C of the ring to the circumferential center of each strut 128 and a second radius rl from the axial centerline C of the ring to the circumferential edge of each facet 126, and wherein the length of the first radius is 75% to 99%, preferably 97% to 99%, often 98% to 99%, more typically 98.5% of the length of the second radius. The circularity in the expanded configuration is preferably greater than 97%, more preferably greater than 98%, and most preferably greater than 98.5%.

[0237] FIG. 10 Various features that can be used to define the structure of a radially expandable helical ring of the present invention are identified, with values as shown in Table 1 below.

[0238] Table 1: Features of helical ring pattern

[0239] While the illustrated stent rings have heretofore been arranged helically, in other cases the stent rings of the present invention can be arranged parallel to one another, often orthogonally to the longitudinal axis of the stent in the unstressed state, and attached longitudinally by axial links. FIGS. 11A-11C is a side view, perspective view, and "exploded" view of such an expandable stent 130 comprising a plurality of such laterally oriented expandable rings 132 joined by axial links 134.

[0240] FIG. 12 ​Various features of structures that can be used to construct expandable stents, such as the expandable stent shown in FIG. 1, are identified, which include a plurality of laterally oriented, axially linked expandable rings, the values of which are shown in Table 2 below. FIGS. 11A-11C

[0241] Table 2: Features of Axially Linked Ring Patterns

[0242] FIG. 13A FIG. 13B are side and perspective views of a stent 140 having radially expandable rings 1422 in a helical arrangement, the radially expandable rings 1422 having a repeating pattern of omega-shaped cells.

[0243] FIGS. 14A-14C are detailed views illustrating different bend patterns that can be used in the radially expandable distal tip rings of the present invention. FIG. 14A A support ring 150 having a serpentine bend pattern is shown in FIG. 14A. FIG. 14B A support ring 152 having a zigzag bend pattern is shown in FIG. 14B. A support ring 154 having a box (square) bend pattern is shown in FIG. 15C.

[0244] FIG. 15A FIG. 15B are "exploded" views of a ring pattern including closed cell box rings 160 shown in their non-expanded and expanded configurations, respectively. The boxes 162 in each ring are elongated circumferentially from a rectangular non-expanded shape shown in FIG. 16A FIG. 15A to a generally hexagonal elongated shape shown in FIG. 16B. This elongation allows each ring to radially expand in response to an opening force provided by a balloon or other expansion tool. FIG. 15B

[0245] FIG. 16A are "exploded" views of a ring 170 including closed cell boxes 172 shown in their non-expanded and expanded configurations, respectively. The ring 170 is similar to the ring 160 illustrated in FIGS. 16 and 17, except that the ring 170 further includes overhanging support elements 174 that recess between circumferentially adjacent box elements 172 attached to circumferential links 176 in the non-expanded configuration FIG. 16B FIG. 15A FIG. 15B FIG. 16A FIG. 16B

[0246] FIG. 17A FIG. 17B ​​​​​​​​​​This is an "expanded" view of ring 180, which includes an alternative closed unit box formed by side members 182 and transverse members 184. When the ring is in a non-expanded configuration, the side members 182 are initially formed in a U-shape, as shown... FIG. 17A As shown in the diagram. When the ring expands radially, the U-shape elongates, as... FIG. 17B As shown in the image.

[0247] Enclosed unit box 190 can also be like FIG. 18 The diagram shows a U-shaped structure that only partially penetrates the space between the transverse members 182.

[0248] Now for reference FIG. 19 , FIG. 20A and FIG. 20B A specific serpentine ring arrangement includes a U-shaped unit 200 having a U-shaped support element 202 extending through an opening 204 between adjacent crown portions 206. The U-shaped support element 202 is configured to expand radially from a coiled structure (e.g., FIG. 20A As shown) extends to extended constructs (such as FIG. 20B (as shown in the image).

[0249] FIGS. 21A-21C The illustration shows the radially expandable support bracket 210 embedded in the polymer membrane 212. FIG. 21C The exemplary method described in the text indicates that the polymer membrane 212 may comprise one or more of the same or different membrane materials. The individual rings 214 of the support bracket 210 will have a serpentine pattern, the serpentine pattern having struts 216 with gaps 218 between the struts 216, as shown. FIG. 21A As shown in the diagram, the support scaffold 210 can be embedded in the polymer membrane 212 by first placing sheets 226 and 228 of one or more desired polymers on the outer and inner surfaces of the ring 214, as shown in the diagram. FIG. 21B As shown in the diagram, by applying heat and pressure to the polymer sheet, the polymer flows into the gap 218, forming a continuous polymer film matrix 230 having an outer surface 232 and an inner surface 234, as illustrated. FIG. 21C As shown in the image.

[0250] FIG. 22 The image shows a portion of a vascular prosthesis comprising a stent 210 and a polymer membrane matrix 212 in its radially extended configuration. The polymer matrix 212 is elastic, allowing it to stretch and thin as the distal tip expands. While the polymer membrane will typically exert a radial closure force, the extended support stent 210 will have sufficient circumferential strength (compressive strength) to resist both the elasticity of the polymer membrane and any other forces that may be applied during deployment and use, thus keeping the distal tip open.

[0251] Now for reference FIGS. 23A-23DThe support bracket 360 pattern includes a support element 368, which is attached to the outer curved wall of the crown 366 connecting to the adjacent pillar 364. FIG. 2 A- FIG. 2 In contrast to pattern C, the support element 368 does not extend between adjacent pillars 364, but rather into the gap or open space between adjacent radially extending circumferential support rings 362. A second difference is that the support rings 362 are continuously connected end-to-end to form a helical pattern. Figure 4C illustrates a radially retractable structure (or delivery structure) suitable for delivery. FIG. 4A and FIG. 4B The image shows the expandable area of ​​the aspiration catheter with a stent pattern. Figure 4D is an image of the same structure shown in Figure 4C after the structure has been expanded by a balloon into an expanded configuration, preferably into the maximum expanded configuration suitable for aspiration. The distal end ring is configured to have a flush end with a pitch angle of approximately 90° relative to the longitudinal axis in the patterned or delivery configuration (as shown). This end and the adjacent ring can be constructed in various ways. In this example, the ring adjacent to the end ring is truncated along the circumferential path of the ring and connected to the end ring, as shown. FIG. 4A As shown in the figure. The end ring and the ring adjacent to the end ring can have different acute angles (or 90°) of pitch angle (as shown in the figure). Alternatively, the rings preceding the end and the end ring can also have the same or different unit amplitudes, unit periods, structural element widths, and / or coronal numbers. The expandable stent 360-degree pattern has a pitch angle of approximately 86°. In other examples, in the patterned or delivery configuration, the pitch angle relative to the longitudinal axis can range from 70° to 89.9°, preferably from 80° to 89°. It is important to note that even if the support elements extend into the gap region (or other space) between adjacent rings, these support elements typically do not extend into the adjacent ring region, thus maintaining the enhanced delivery capability of the expandable stent segment within the vascular anatomy.

[0252] Now for reference FIG. 24A and FIG. 24BSupport stent 370, having a helical pattern similar to that of stent 360, includes a plurality of radially expandable circumferential support rings 372, which include struts 374 and crowns 376. Support elements 378 differ from support elements 68 in that they have bifurcated end support disks. The support elements form a circumferential envelope along the stent length or around the stent circumference along the entire stent length. The circumferential envelope typically has a fixed axial length, width, shape, and / or geometry (as shown) and provides support for the expandable membrane(s) against collapse following application of vacuum at the proximal end of the aspiration catheter after expansion from the delivery configuration to the expanded configuration and in the event of occlusion or blockage of the distal tip by clot or other material. In this example, the support element base is located at the crown peak region. The support element extends axially beyond each ring amplitude or beyond at least some ring amplitudes, where the amplitude is the axial distance between two adjacent peaks on the same ring. In some cases, the support element can have different lengths, widths, shapes, or geometries within or along at least some of the rings, where the different widths, lengths, shapes, or geometries continue to provide support for the expandable membrane(s) against collapse under vacuum in the expanded configuration. The proximal end ring of the expandable stent is composed of an expandable segment (shown) and a non-expandable segment (truncated), defining a transition between the expandable stent and the reinforcing coil. The first non-expandable reinforcing coil segment can be attached to one or more locations on the adjacent expandable ring and / or adjacent reinforcing coil turn, or remain unlinked, rather than being linked to adjacent turns in a helical pattern.

[0253] Reference is now made to FIG. 25A and FIG. 25BSupport stents 380 have a helical pattern similar to that of stents 360 and 370 and include a plurality of radially expandable circumferential support rings 382 that include struts 384 connected by crowns 386. Support elements 388 differ from support elements 368 and 378 in that they extend primarily in the circumferential direction, allowing adjacent support rings 382 to be positioned very closely together in the axial direction prior to expansion. In this example, the support elements extend substantially into the entire gap between the rings, leaving a small gap between adjacent rings. This type of support element configuration provides enhanced resistance to collapse for one or more membranes when the membrane is expanded from a delivery configuration to an expanded configuration and a vacuum is applied at the proximal end of the aspiration catheter. On the other hand, this less gap design is configured to be more suitable for non-tortuous anatomies. In this and other examples, it is important to note the symmetry of the support elements within each ring, within at least some rings, and more preferably along substantially the entire stent length. This symmetry provides resistance to deformation and / or kinking when passing through the vasculature. It also provides enhanced resistance to collapse for the expandable membrane. In some cases, one or more support elements can be missing within one or more rings, providing an asymmetric support element pattern, but still maintaining resistance to collapse for the expandable membrane.

[0254] As currently shown, the support elements have generally included a straight structure with a base end attached to a radially expandable circumferential support ring and a free end in the space between adjacent struts, between adjacent struts connected by a crown, or in the gap between adjacent support rings. However, as shown in FIGS. 26A-26N the support elements can vary greatly in geometry and attachment location. FIG. 26A Support element 404a shown in has a base end attached to the inner radius or wall of crown 402 and a free end terminating in an elliptical contact pad 405a in the V-shaped space between adjacent struts 400. Elliptical contact pad 405a has a major axis aligned in the axial direction. As shown in FIG. 26B support element 404b terminates in an elliptical contact pad 405b having a major axis aligned in the circumferential direction.

[0255] FIG. 26C Support element 404c in FIG. 26D is similar to the previously described support elements, differing in that it terminates in a triangular contact pad 405c having a pointed tip oriented away from the attached crown.FIG. 26G The support element 404g shown has a base attached to the center of the inner wall of the crown 402 and a circular contact pad 405g, the circular contact pad 405g having a hole at its center that is circumferentially aligned with the attachment point.

[0256] FIG. 26E , FIG. 26F , FIG. 26H and FIG. 26I The image shows a support element with a bending axis. FIG. 26E The support element 404e shown has an S-shaped shaft with a base end attached to one side of the outer curve of the crown 402 and a circular contact pad 405e circumferentially aligned with the outermost point of the crown. FIG. 26F The support element 404f shown has a base attached to the outermost point of the crown 402 and a circular contact pad 405f circumferentially aligned with the outermost point. FIG. 26H The support element 404h shown has a base attached to the outermost point of the crown 402, a shaft with a simple 90° bend, and a circular contact pad 405h axially offset from the outermost point. FIG. 26I The support element 404i shown has a base end attached along the length of the support column 400, and a circular contact pad 405i attached to its free end. The shaft has a bend of approximately 120°.

[0257] FIG. 26J The support element 404j shown is... FIG. 2 A- FIG. 2 The support element shown in C is similar, with support element 404j having a circular contact pad 405j at the free end of the linear shaft, but including a short slit 406j formed in the crown 402j to allow for increased radial expansion.

[0258] In other examples, the support element may have bends, bifurcations, multiple contact pads, and other structural features to enhance its ability to support the expandable membrane in the region between adjacent struts and / or adjacent support rings. For example... FIG. 26K As shown, the support element 404k branches into a Y shape and has a pair of contact pads 405k. FIG. 26L The support element 404 shown It also has a forked portion, which has a pair of contact pads 405 and the third contact pad 406 located at the bifurcation point .

[0259] In other examples, the support element can be formed as a linear segment of a link, which optionally has contact pads at some or all of the connections between the links. For example, as FIG. 26M and FIG. 26NAs shown in FIG. 4M, support elements 404m and 404n each include a pair of linear segments with contact pads 405m and 405n at the terminal free ends, respectively, and internal contact pads 406m and 406n at the connections between the segments, respectively. The linear segments in support element 404m are attached at approximately 120° angles, while the linear segments in support element 404n are attached at right angles (90° angles).

[0260] Referring now to FIGS. 26O-26R , various T-shaped support elements are illustrated, with base ends attached to the inner surface of a U-shaped crown. The T-ends can extend into the gap between adjacent rings, and can be flush with any ring, as shown in FIG. 26O and FIG. 26P . Alternatively, the T-ends can be flush with the ring to which they are attached ( FIG. 26Q ), or can extend into the middle gap without contacting any ring ( FIG. 26R ). In some examples, the support elements within each ring extend in the same direction, as shown in FIG. 26O . Alternatively, the support elements within each ring can extend in opposite directions, as shown in FIG. 26P .

[0261] Referring now to FIG. 26S , support elements with base ends attached to the inner surface of a U-shaped crown can have unattached ends with different terminal geometries that extend into the gap between adjacent rings. For example, some of the terminals can be provided with bumpers or stop elements configured to engage adjacent rings to maintain a desired gap region therebetween.

[0262] Referring now to FIG. 26T , support elements with base ends attached to the inner surface of a box-shaped or U-shaped crown can have recessed unattached ends (free ends) that fill substantially all of the space between adjacent struts on each ring (or fill or cover substantially all of the space between adjacent struts on each ring in a patterned or delivered configuration). This is the preferred ring geometry, as shown in more detail in FIG. 11A through FIG. 11D.

[0263] Referring now to FIGS. 26U-26Y and FIG. 26P , various support elements are illustrated, with base ends attached to the outer surface of a U-shaped crown. The unattached ends (free ends) of the support elements can have T-shapes, L-shapes, skew shapes, or various other geometries, and will extend fully or partially into the gap between adjacent ring elements. The terminals can be flush with the adjacent rings, as shown in FIG. 26O , FIG. 26U , FIG. 26W , FIG. 26X andFIG. 26Y The intermediate gap can be left open without contacting the adjacent ring (as shown in FIG. 26V ).

[0264] Reference is now made to FIGS. 26Z-26AD Various support elements can be attached to one side of the crown and extend circumferentially toward an adjacent crown. FIG. 26Z 、 FIG. 26AB and FIG. 26AC show a single lateral support element, while FIG. 26AA and FIG. 26AD show a pair of sliding lateral elements. The lateral elements can optionally extend onto the outer surface of the adjacent crown, as shown in FIG. 26AC .

[0265] As shown in FIGS. 26AE-26AP , the support elements can be formed as a "lock and key" structure, comprising a straight element or male element that is slightly accommodated in a slotted or "clevis" member. Such support elements can accommodate circumferential and / or axial movement of the adjacent ring element as the stent is radially expanded. Such expandable or accommodating support elements can extend through the opening of a U-shaped cell (comprising a pair of struts joined by a crown), as shown in FIG. 26AD and FIG. 26AE , or can extend from one ring to an adjacent ring, as shown in FIGS. 26AF-26AP . The base of the male element and / or the clevis element can be attached to the inner or outer surface of the crown, the inner surface of the strut, and can extend in the circumferential direction or can be angled relative to the circumference. Either or both of the male element and the angled strut or clevis element can have one or more bends. FIGS. 26AE-26AP Various geometries and combinations are shown in

[0266] FIG. 27 is an "exploded" view of another example of a support stent 410 having adjacently linked radially expandable circumferential support rings 412 having different widths and different configurations of support elements 414 constructed in accordance with the principles of the present invention. As with the previous example, the support rings 412 are comprised of pairs of struts 415 joined by a crown 416. Support element 414a is a linear beam similar to support element 52 described with reference to FIG. 2 A- FIG. 2 D. Support element 414b has a single bend and is similar to support element 404m shown in FIG. 26M , but lacks an intermediate contact pad between the adjacent linear segments and is attached to the strut 415 rather than the crown 416. Support element 414c is a short straight beam with a distal contact pad. Support element 414d has a single bend similar to support element 404n shown in FIG. 26HThe illustrated stent ring can have a different number of crowns on adjacent rings, a different cell period on adjacent rings, different support elements on adjacent rings having different shapes, numbers, and frequencies, different gaps between rings, and / or different ring amplitudes.

[0267] As shown in FIG. 28 and FIG. 29 The support stent 420 includes a plurality of radially expandable circumferential support rings 422 that include struts 424 and crowns 426. Unlike the previous examples, there are no support elements attached to the support rings 422. Instead, the support rings 422 have a pattern that inherently provides enhanced support to an attached expandable membrane when used in an expandable distal tip of an aspiration catheter. More specifically, the support rings include serpentine or zigzag rings having a width W ranging from 0.1 mm to 1 mm, preferably 0.3 mm to 0.4 mm; a gap G between adjacent rings ranging from 0 mm to 1 mm, preferably 0.05 mm to 0.4 mm; crowns arranged along the axis separated by a pitch CS ranging from 0.1 mm to 1 mm, preferably 0.25 mm to 0.4 mm; and struts diverging from the crowns at an angle a ranging from 0° to 90°, preferably 20° to 40° prior to expansion.

[0268] FIG. 30 Another alternative embodiment of a support stent 440 of the present invention is illustrated, having discrete support pads 450 located between struts 444 of serpentine radially expandable support rings 442. The struts 444 are joined by crowns 446 in a conventional manner, and adjacent support rings 442 are joined by links 447. The support pads 450 are attached to a support membrane 452 in the V-shaped regions between adjacent struts 444, but are not otherwise attached to the rest of the expandable support structure 440. The support pads 450, preferably but not necessarily, can have a triangular shape that corresponds to the V-shaped regions to which they are attached. They can also have other shapes, such as circular, elliptical, or other rounded shapes.

[0269] As illustrated heretofore in this application, exemplary helical support structures generally consist of a single helically wound serpentine, zigzag, or other ribbon having flexures that allow elongation when the associated ring is radially expanded. In other cases, as illustrated in FIG. 31A and FIG. 31B The support structures 500 and 502 can have two, three, four, or more helically nested helical rings. As specifically shown in FIG. 31A The support structure 500 includes a first helically nested ring 510 and a second helically nested ring 512, respectively. As specifically shown in FIG. 31BAs shown in detail, the support structure 502 includes a first helical nested ring 520, a second helical nested ring 522, and a third helical nested ring 524, respectively.

[0270] FIG. 32 and FIG. 33 FIG. 1 illustrates how the "pitch angle" of a helical stent can be measured. FIG. 32 FIG. 1 illustrates the "unrolled" pattern of an exemplary helical stent 600 in its crimped or pre-expanded configuration, while FIG. 14B FIG. 1 illustrates the "unrolled" pattern of the same helical stent 600' in its radially expanded configuration. The pitch angle of the pre-expanded stent 600 is measured between a line LI along the longitudinal axis of the stent and a line L2 drawn parallel to the rings 602 in the stent. The pitch angle al of the stent 600 in the pre-expanded or delivery configuration is typically 70° to 89.9°, or more typically 80° to 89.9°, preferably 84° to 89.9°, and more preferably 85° to 89°, and most preferably 86° to 88°. For any given stent, the pitch angle a2 will be greater than the pitch angle al, as the pitch angle increases as the stent is radially expanded, approaching 90° when the stent is fully expanded.

[0271] FIG. 34A and FIG. 34B is a side view and "unrolled" view of an expandable stent 680 that includes a plurality of parallel, axially linked expandable rings 682 that are joined by axially links 684 that are tilted at an acute pitch angle a3 relative to the longitudinal axis of the stent.

[0272] FIG. 35 is an "unrolled" view of an expandable stent 690 that has segments 692 and 694 with cells that are aligned in-phase and out-of-phase, respectively.

[0273] FIG. 36 is an "unrolled" view of an expandable stent 700 that includes a plurality of rings 702 that have gaps 704 of different lengths between them.

[0274] FIG. 37A is an "unrolled" view of an expandable stent 800 that includes a plurality of rings 802 arranged in a helical pattern that have gaps 804 between them. The rings 802 are "smooth", i.e., linear and free of bends and curves in the unrolled pattern. As shown in detail view FIG. 37B , the rings 802 will each have a serpentine pattern. Although FIG. 37B illustrates a simple serpentine pattern that includes struts 806 joined by crowns 808, the rings 802 can include any cell pattern described herein or otherwise known in the art.

[0275] FIG. 37C to FIG. 37E yes FIG. 37A Rotating side view of the expandable bracket 800. FIG. 37D The view of the bracket 800 shown is relative to FIG. 37C The view in the middle is rotated 90° in the first rotation direction, while FIG. 37E The view shown is rotated 90° in the opposite direction of rotation. Since the ring 802 of the bracket 800 is "smooth," i.e., without bends, the side view does not change as the bracket rotates about its longitudinal axis.

[0276] FIG. 38A This is an "unfolded" view of an expandable support 820, which includes a plurality of loops 522 arranged in a spiral pattern with gaps 524 between them, wherein each loop has a first curved shape in the unfolded pattern. Each loop 522 is non-linear and includes two curved or bent regions 532, one of which spans the connecting ends, such as 534a and 534b, when the support is rolled up. See detailed view. FIG. 38B As shown, rings 522 will each have a serpentine pattern. Although FIG. 38B The illustration depicts a simple serpentine pattern including struts 526 connected by crown 528, but ring 522 may include any unit pattern described herein or otherwise known in the art.

[0277] FIG. 38C to FIG. 38E yes FIG. 38A Rotating side view of the expandable bracket 520. FIG. 38D The view of the bracket 520 shown is relative to FIG. 38C The view in the middle is rotated 90° in the first rotation direction, while FIG. 38E The view shown is rotated 90° in the opposite direction of rotation. The curve 532 in the ring 522 of the bracket 520 causes the observed tilt of each ring 522 to change from... FIG. 38D The rightward tilt offset shown is FIG. 38E It is tilted to the left as shown.

[0278] FIG. 39A This is an "unfolded" view of an expandable support 840, which includes a plurality of loops 842 arranged in a spiral pattern with gaps 844 between them, wherein individual loops have a second curved shape in the unfolded pattern. Each individual loop 842 is non-linear and includes three curved or bent regions 852 (one of which spans connecting ends 854a and 854b when the support is rolled up). See detailed view. FIG. 39B As shown, rings 842 will each have a serpentine pattern. Although FIG. 39BThe middle illustration shows a simple serpentine pattern including struts 846 joined by crowns 848, but the rings 842 can include any cell pattern described herein or otherwise known in the art.

[0279] FIG. 39C to FIG. 39E is a rotated side view of the expandable stent 840. FIG. 39A FIG. 39D The views of the stent 840 shown in FIG. 39C are rotated 90° in the first rotational direction from the views in FIG. 39E are rotated 90° in the opposite rotational direction from the views shown inThe curvature 852 in the rings 842 of the stent 840 causes the observed tilt of each ring 842 to shift back and forth as the stent is rotated relative to its longitudinal axis, as can be seen by comparing the images in FIG. 39C , FIG. 39D and FIG. 39E .

[0280] FIG. 40 is an "unfolded" view of a ring pattern shown prior to expansion including rings 880 having S-shaped expandable elements 882 joined by non-expandable circumferential links 884.

[0281] FIG. 41 is an "unfolded" view of a ring pattern including rings 890 formed from wire bent into a serpentine pattern having integrated overhanging support elements 892 formed from tight U-shaped turns that are bonded together by gluing, welding, fusing, or otherwise joining to prevent separation.

[0282] Referring now to FIG. 42A to FIG. 42C , a balloon expandable vascular prosthesis 900 is delivered through a balloon 902 of a balloon catheter 904 to a target aneurysm AS in a cerebral artery CA. The vascular prosthesis 900 can be any of the previously described balloon expandable embodiments or designs, and when introduced through a sheath 906 over a guide wire 908 using conventional Seldinger techniques, the vascular prosthesis 900 will initially be in its radially collapsed configuration, as shown in FIG. 42A . After the vascular prosthesis 900 is positioned across the neck N of the aneurysm sac AS, the balloon 900 is expanded to cover the neck N of the aneurysm sac with the main body of the vascular prosthesis 900, as shown in FIG. 42B . The balloon catheter 906 can then be withdrawn from the vascular prosthesis 900 through the sheath 906, as shown in FIG. 42C , and the sheath 906 can subsequently be removed from the patient in the conventional manner.

[0283] Referring now to FIG. 43A to FIG. 43C, a self-expanding vascular prosthesis 920 is delivered through the lumen of a microcatheter catheter 922 to a target aneurysm AS in a cerebral artery CA. The vascular prosthesis 920 can be any of the self-expanding embodiments or designs described previously. The microcatheter 922 is introduced through a sheath 924 placed in the conventional manner to have the distal end 926 end proximate the neck N of the target aneurysm sac AS. Upon introduction through the lumen of the microcatheter 922 (typically pushed by a pusher not shown), the vascular prosthesis 920 will initially be in its radially collapsed delivery configuration as shown in FIG. 43A . After the distal end 926 of the microcatheter 922 is positioned at the aneurysm neck N, the vascular prosthesis 920 will be pushed out of the distal end 926 while the microcatheter is pulled to position the vascular prosthesis 920 across the aneurysm neck as shown in FIG. 43B . The microcatheter 922 can then be withdrawn through the sheath 924 and the sheath 924 can subsequently be removed from the patient in the conventional manner. FIG. 43C

[0284] While certain aspects or examples of this disclosure have been described with specificity, it will be understood that various other modifications and changes can be made to aspects or examples of this disclosure without departing from the scope of the disclosure. It is intended that the appended claims cover all such changes and modifications. It is also contemplated that various combinations or sub-combinations of aspects, embodiments or examples can be made, and still fall within the scope of the disclosure. Further, it is intended that each aspect, embodiment or example disclosed in this disclosure be taken in its broadest sense and be afforded all permutations, equivalents, and / or substitutions that could reasonably be inferred from the disclosure. Additionally, the described aspects, embodiments or examples are intended to be combinations of aspects, embodiments or examples disclosed in this disclosure, and are not intended to be limited to the aspects, embodiments or examples specifically disclosed. It is intended that the aspects, embodiments or examples disclosed in this disclosure be taken in their broadest sense and be afforded all permutations, equivalents, and / or substitutions that could reasonably be inferred from the disclosure.​

Claims

1. An endovascular prosthesis comprising: a stent comprising a plurality of radially expandable circumferential rings arranged along a longitudinal axis with circumferential gaps between the plurality of radially expandable circumferential rings, wherein at least some of the radially expandable circumferential rings comprise cells comprising struts joined by crowns; wherein midpoints in the struts of the cells have a radius R measured from the longitudinal axis of the stent; wherein midpoints in the gaps between circumferentially adjacent cells have a radius r measured from the longitudinal axis of the stent; wherein an outer surface of the stent retains at least 97% circularity measured as r / R x 100 after the stent is radially expanded up to 200% from the delivery radius; and wherein the stent is configured to radially expand from a delivery configuration to a deployed configuration in a target blood vessel.

2. The endovascular prosthesis of claim 1, wherein the radially expandable circumferential rings are arranged end to end in a helical pattern.

3. The endovascular prosthesis of claim 1 or 2, wherein the stent is balloon expandable.

4. The endovascular prosthesis of claim 1 or 2, wherein the stent is self-expanding.

5. The endovascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane retains at least 97% circularity measured as r / R x 100 after the stent is radially expanded up to 100% from the delivery radius.

6. The endovascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane retains at least 97% circularity measured as r / R x 100 after the stent is radially expanded up to 50% from the delivery radius.

7. The endovascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane retains at least 98% circularity measured as r / R x 100 after the stent is radially expanded from the delivery radius.

8. The endovascular prosthesis of any one of claims 1 to 4, wherein the outer surface of the membrane retains at least 98.5% circularity measured as r / R x 100 after the stent is radially expanded from the delivery radius.

9. The endovascular prosthesis of any one of claims 1 to 8, wherein the stent is open and the endovascular prosthesis comprises a stent.

10. The endovascular prosthesis of any one of claims 1 to 8, further comprising a membrane attached over at least a portion of the stent, and wherein the endovascular prosthesis comprises a stent graft.

11. The endovascular prosthesis of claim 10, wherein the membrane comprises a non-porous material.

12. The endovascular prosthesis of claim 10, wherein the membrane comprises a porous material.

13. The endovascular prosthesis of any one of claims 10 to 12, wherein the membrane is perforated.

14. The endovascular prosthesis of any one of claims 10 to 13, wherein the membrane is configured to extend completely over the stent or coil.

15. The endovascular prosthesis of any one of claims 10-13, wherein the membrane is configured to extend over a central portion of the stent or coil, leaving terminal regions uncovered.

16. The endovascular prosthesis of any one of claims 10-15, wherein the membrane carries a pharmaceutically active agent.

17. An endovascular prosthesis comprising: an expandable coil comprising consecutive helical turns disposed along a longitudinal axis, the expandable coil comprising undulating bends and struts, and the consecutive helical turns having gaps therebetween, wherein the consecutive helical turns are inclined at an acute pitch angle relative to the longitudinal axis in a range of 85° to 89.9°, preferably 86° to 89°, and more preferably 86° to 88°; and wherein the expandable coil is configured to radially expand from a delivery configuration having a radially collapsed diameter to a deployed configuration having a radially expanded configuration.

18. The endovascular prosthesis of claim 17, wherein: the helical turns have a radius R measured from the longitudinal axis of the coil; wherein a flat facet in an outer surface of a membrane attached on at least a portion of the coil and spanning the gaps between circumferentially adjacent helical turns has a radius r measured from the longitudinal axis of the stent; and wherein the outer surface of the membrane maintains a roundness of at least 97% measured as r / R x 100 after the stent is radially expanded up to 200% from the delivery radius.

19. The endovascular prosthesis of claim 17 or 18, wherein at least some of the helical turns have a peak-to-peak distance of helical turns (helical turn amplitude) in a range of 0.05 mm to 0.35 mm in a ring when the radially expandable distal tip is in its delivery radius.

20. The endovascular prosthesis of any one of claims 17 or 18, wherein at least some of the helical turns have a peak-to-peak distance of helical turns (helical turn amplitude) in a range of 0.1 mm to 0.25 mm in a ring when the radially expandable distal tip is in its delivery radius.

21. The endovascular prosthesis of any one of claims 17 or 18, wherein at least some of the helical turns have a peak-to-peak distance of helical turns (helical turn amplitude) in a range of 0.1 mm to 0.2 mm in a ring when the radially expandable distal tip is in its delivery radius.

22. The endovascular prosthesis of any one of claims 17-21, wherein the expandable coil is balloon-expandable.

23. The endovascular prosthesis of any one of claims 17-21, wherein the expandable coil is self-expanding.

24. The endovascular prosthesis of any one of claims 17-23, wherein the expandable coil is open and the endovascular prosthesis comprises a stent.

25. The endovascular prosthesis of any one of claims 17-23, further comprising a membrane attached on at least a portion of the expandable coil, and wherein the endovascular prosthesis comprises a stent graft.

26. The intravascular prosthesis of claim 25, wherein the membrane comprises a non-porous material.

27. The intravascular prosthesis of claim 25, wherein the membrane comprises a porous material.

28. The intravascular prosthesis according to any one of claims 25 to 27, wherein the membrane is perforated.

29. The intravascular prosthesis according to any one of claims 25 to 28, wherein the membrane is configured to extend fully over the expandable coil.

30. The intravascular prosthesis according to any one of claims 25 to 29, wherein the membrane is configured to extend over the central portion of the expandable coil, leaving the distal region uncovered.

31. The intravascular prosthesis according to any one of claims 25 to 30, wherein the membrane carries a pharmaceutically active agent.

32. An intravascular prosthesis, comprising: A support, comprising a plurality of radially expandable circumferential rings arranged along a longitudinal axis, with circumferential gaps between the plurality of radially expandable circumferential rings, wherein at least some of the radially expandable circumferential rings include serrated or sawtooth structures, the serrated or sawtooth structures including struts connected by crowns; and A plurality of support elements, each support element having a base end and a free end, wherein the base end of the support element is attached to the inside of the crown, and the free end is disposed between adjacent struts attached to the crown.

33. The intravascular prosthesis of claim 32, wherein at least some of the free ends of the support element are recessed within the circumferential ring and do not protrude into the circumferential gap before the distal tip extends radially.

34. The intravascular prosthesis of claim 32 or 33, wherein, after the distal tip is extended, at least some of the free ends of the support element protrude into the circumferential gap.

35. The intravascular prosthesis according to any one of claims 32 to 34, wherein the support element is configured to be located within a cylindrical envelope defined by the stent.

36. The intravascular prosthesis according to any one of claims 32 to 35, wherein the stent is balloon-expandable.

37. The intravascular prosthesis according to any one of claims 32 to 35, wherein the stent is self-expanding.

38. The intravascular prosthesis according to claims 32 to 37, wherein the stent is open, and the intravascular prosthesis comprises a stent.

39. The intravascular prosthesis of claims 32 to 37, further comprising a membrane attached to at least a portion of the stent, wherein the intravascular prosthesis comprises a stent graft.

40. The intravascular prosthesis of claim 39, wherein the membrane comprises a non-porous material.

41. The intravascular prosthesis of claim 39, wherein the membrane comprises a porous material.

42. The intravascular prosthesis according to any one of claims 39 to 41, wherein the membrane is perforated.

43. The intravascular prosthesis according to any one of claims 39 to 42, wherein the membrane is configured to extend fully over the stent or coil.

44. The endovascular prosthesis of any of claims 39-42, wherein the membrane is configured to extend over a central portion of the stent or coil, leaving terminal regions uncovered.

45. The endovascular prosthesis of any of claims 39-44, wherein the membrane carries a pharmaceutically active agent.

46. An endovascular prosthesis delivery system, comprising: an elongated catheter body having a distal end, a proximal end, and an inflatable balloon at the distal end; and a balloon-expandable endovascular prosthesis according to any of the preceding claims mounted on the inflatable balloon.

47. An endovascular prosthesis delivery system, comprising an elongated sheath having a distal end and a proximal end; and a self-expanding endovascular prosthesis according to any of the preceding claims retracted within a lumen at the distal end of the elongated sheath.

48. A method of delivering an endovascular prosthesis to a patient’s vasculature, the method comprising: coupling an endovascular prosthesis of any of the preceding claims in its radially retracted configuration to a distal end of a delivery device; positioning the distal end of the delivery device at a target aneurysm within a patient’s vasculature; and deploying the endovascular prosthesis to span the target aneurysm.

49. The method of claim 48, wherein deploying comprises expanding the endovascular prosthesis using an inflatable balloon.

50. The method of claim 48, wherein deploying comprises releasing the endovascular prosthesis from radial constraint within a delivery sheath. ​

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