The subject technology relates generally to methods and devices for diverting blood flow in a blood vessel, and particularly to inhibiting blood flow into an aneurysm. Some embodiments of the subject technology relate to flow-diverting devices including a plurality of interconnected struts.
Aneurysms are an abnormal bulging or ballooning of a blood vessel that can result from the vessel wall being weakened by disease, injury, or a congenital abnormality. Aneurysms have thin, weak walls and have a tendency to rupture, which can lead to stroke, death, disability, etc. One method of treating aneurysms includes inserting a flow-diverting stent or braid into a parent vessel that includes the aneurysm to be treated. Such stents or braids can be inserted into a vessel in a collapsed state, positioned next to the neck of the aneurysm, and expanded into apposition with the vessel wall. If the stent or braid has a sufficiently low porosity, it can function to block the flow of blood through the device and into the aneurysm to induce embolization of the aneurysm.
However, some aneurysms—and especially cerebral aneurysms—are located in small and tortuous portions of the vasculature. Current designs for flow-diverting stents or braids have difficulty achieving a snug fit across the neck of the aneurysm if the parent vessel is curved, twisted, or forked. For example, current designs generally suffer from crimping or kinking when positioned in such tortuous vessels. This can make it more difficult to position a flow-diverting device and can cause the device to have an inadequate porosity as the device is expanded within the vessel. Also, current designs often undesirably block blood flow to branching or secondary vessels that are close to the aneurysm. Accordingly, there exists a need for improved flow-diverting devices for treating aneurysms.
Expandable devices can be delivered into vascular system to divert flow. According to some embodiments, expandable devices are provided for treating aneurysms by diverting flow. A flow-diverting expandable device can comprise a plurality of struts and/or bridges and configured to be implanted in a blood vessel. The expandable device can be expandable to an expanded state at an aneurysm. The expandable device can have at least a section for spanning the neck of the aneurysm and a plurality of pores or openings located between the struts/bridges. The expandable device can have a sidewall and a plurality of pores/openings in the sidewall that are sized to inhibit flow of blood through the sidewall into an aneurysm to a degree sufficient to lead to thrombosis and healing of the aneurysm when the expandable device is positioned in a blood vessel and adjacent to the aneurysm. The subject technology is illustrated, for example, according to various aspects described below.
Further, some embodiments can provide a delivery system for treating an aneurysm. The system can comprise a microcatheter configured to be implanted into a blood vessel, a core member, extending within the microcatheter, having a distal segment, and the device extending along the core member distal segment.
The subject technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the subject technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the subject technology.
Clause 1. An expandable device comprising:
Clause 2. The expandable device of clause 1, wherein a first one of the bridge sections comprises first bridge members winding in a first helical direction about an axis of the expandable device and a second one of the bridge sections comprises second bridge members winding in a second helical direction about the axis of the expandable device, the first helical direction being opposite the second helical direction.
Clause 3. The expandable device of clause 1, wherein each of the connector struts is coupled to another connector strut at an apex.
Clause 4. The expandable device of clause 3, wherein each apex is coupled to one of the bridge members.
Clause 5. The expandable device of clause 3, wherein some of the apices are not coupled to any of the bridge members.
Clause 6. The expandable device of clause 3, wherein each bridge member is coupled to a connector strut at a location other than the apex.
Clause 7. The expandable device of clause 1, wherein each bridge member is coupled to a connector strut with a region of the bridge member that is tangent to the connector strut.
Clause 8. The expandable device of clause 1, wherein at least a portion of each of the connector struts of a connector section are parallel to each other.
Clause 9. The expandable device of clause 1, wherein some of the bridge members extend entirely through one of the connector sections without being coupled to a connector strut of the one of the connector sections.
Clause 10. The expandable device of clause 1, further comprising anchor sections at longitudinal ends of the expandable device, each of the anchor sections comprising a plurality of closed cells.
Clause 11. The expandable device of clause 1 wherein the expandable device is a mesh.
Clause 12. The expandable device of clause 11 wherein the expandable device is a laser cut sheet.
Clause 13. The expandable device of clause 11 wherein the mesh is non-braided.
Clause 14. The expandable device of clause 1 wherein the device is non-braided.
Clause 15. A device for treating an aneurysm, the device comprising:
Clause 16. The device of clause 15, wherein a first one of the bridge sections comprises first bridge struts winding in a first helical direction about an axis of the mesh structure and a second one of the bridge sections comprises second bridge struts winding in a second helical direction about the axis of the mesh structure, the first helical direction being opposite the second helical direction.
Clause 17. The device of clause 15, wherein each of the connector struts is coupled to another connector strut at an apex.
Clause 18. The device of clause 17, wherein each apex is coupled to one of the bridge struts.
Clause 19. The device of clause 17, wherein some of the apices are not coupled to any of the bridge struts.
Clause 20. The device of clause 17, wherein each bridge strut is coupled to a connector strut at a location other than the apex.
Clause 21. The device of clause 15, wherein each bridge strut is coupled to a connector strut with a region of the bridge strut that is tangent to the connector strut.
Clause 22. The device of clause 15, wherein at least a portion of each of the connector struts of a connector section are parallel to each other.
Clause 23. The device of clause 15, wherein some of the bridge struts extend entirely through one of the connector sections without being coupled to a connector strut of the one of the connector sections.
Clause 24. The device of clause 15, further comprising anchor sections at longitudinal ends of the expandable device, each of the anchor sections comprising a plurality of closed cells.
Clause 25. The device of clause 15 wherein the mesh structure is a laser cut sheet.
Clause 26. The device of clause 15 wherein the mesh structure is non-braided.
Clause 27. The device of clause 15 wherein the mesh structure is made of a superelastic material.
Additional features and advantages of the subject technology will be set forth in the description below, and in part will be apparent from the description, or may be learned by practice of the subject technology. The advantages of the subject technology will be realized and attained by the structure particularly pointed out in the written description and clauses hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the subject technology.
The accompanying drawings, which are included to provide further understanding of the subject technology and are incorporated in and constitute a part of this description, illustrate aspects of the subject technology and, together with the specification, serve to explain principles of the subject technology.
In the following detailed description, specific details are set forth to provide an understanding of the subject technology. However, the subject technology may be practiced without some of these specific details. In some instances, well-known structures and techniques have not been shown in detail so as not to obscure the subject technology.
An expandable device comprising a thin film forming a mesh can be used to treat an aneurysm. The expandable device can impede blood flow along an aneurysmal flow path between the prevailing direction of arterial flow and the interior of the aneurysm via, e.g., high pore density, small pore size and/or high material coverage across the aneurysmal flow path, and facilitate endothelial growth across the neck of the aneurysm or otherwise across the aneurysmal flow path. The expandable device can comprise a single component, low profile, high pore density flow diverter of a single material and/or of monolithic construction. The expandable device can facilitate accurate placement by requiring less foreshortening as compared to other commercially available devices, including braided devices. The expandable device can have a thickness that is small enough to enable placement in smaller blood vessels, thereby opening new areas of treatment for flow diversion.
According to some embodiments, an expandable device, such as a stent, can have a flow diverting section or other portion of the device that provides embolic properties so as to interfere with blood flow in (or into) the body space (e.g., an aneurysm) in (or across) which the device is deployed. The sidewall material coverage, porosity, and/or pore size of one or more sections of the device can be selected to interfere with blood flow to a degree sufficient to lead to thrombosis of the aneurysm or other body space.
According to some embodiments, the expandable device can be configured to interfere with blood flow to generally reduce the exchange of blood between the parent vessel and an aneurysm, which can induce thrombosis of the aneurysm. A device (or a device component, such as a sidewall of a stent or a section of such a sidewall) that interferes with blood flow can be said to have a “flow diverting” property.
According to some embodiments, a porosity of the expandable device is equal to a ratio of an open surf ace area of the expandable device to a total surface area of the expandable device. The expandable device may comprise a plurality of struts, which form pores or cells as open areas between the struts.
The device can exhibit a porosity configured to reduce haemodynamic flow into and/or induce thrombosis within an aneurysm. The device can simultaneously allow perfusion to an adjacent branch vessel whose ostium is crossed by a portion of the device. The device can exhibit a high degree of flexibility due to the materials used, the density (i.e., the porosity) of the struts, and the arrangement of struts.
The device can be self-expanding to a relaxed state or an expanded state. As used herein, the relaxed state is one to which the expandable device will self-expand in the absence of any containment or external forces. As used herein, expanded state is one to which the expandable device is capable of self-expanding, ignoring any containment, such by as a blood vessel. For example and simplicity of measurement, this expanded state can be one to which the expandable device will self-expand within a straight, non-tapering cylindrical tube with an inside diameter that is slightly smaller than the maximum diameter of the expandable device in the relaxed state.
The struts and bridge configuration of the expandable device may be formed, for example, by laser cutting a pre-formed tube or sheet, by interconnecting components (e.g., by laser welding), by vapor deposition techniques, or combinations thereof. A more detailed description of methods by which an expandable device may be formed is provided further herein.
According to some embodiments, the expandable device may include a plurality of individual struts and individual cells, as well as a first longitudinal edge and a second longitudinal edge. The first longitudinal edge and the second longitudinal edge may be connected to each other to form a substantially cylindrical shape or a circumferentially continuous cylindrical shape by welding, soldering, or otherwise joining the struts or edges.
According to some embodiments in which the device is not a circumferentially continuous cylinder, the first edge and second edge may be formed, for example, by cutting a preformed, etched or laser-cut tube longitudinally along the length of the tube. Regardless of the manner of forming, the expandable device may be rolled or curled such that the first and second longitudinal edges overlap one another when the expandable device is in a compressed state and/or an expanded state. Upon release from a constraint (e.g. upon exiting a catheter), the expandable device (when configured to be self-expanding) may spring open and attempt to assume an expanded state.
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Many embodiments of the subject technology are directed to expandable, flow-diverting mesh devices formed of a non-braided, thin-film mesh structure that includes a plurality of helical bridge struts (described in greater detail below). The mesh devices of the subject technology provide several advantages over conventional, braided flow-diverting devices, especially braided devices. For example, because the mesh devices disclosed herein are non-braided, they foreshorten significantly less than braided devices and thus may be more accurately deployed and positioned within the parent vessel. Moreover, many of the mesh devices disclosed herein are formed of a monolithic piece of metal and thus may have a very small wall thickness (e.g., about 15-20 microns), thereby enabling placement in smaller blood vessels and allowing new anatomical areas of treatment for flow diversion. Finally, because of the density, shape and arrangement of struts, the mesh devices of the subject technology are more flexible than conventional stents and may be positioned around tight corners or bends without kinking.
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According to some embodiments, a helical winding direction of the bridge members 160 of one bridge section 150 can be different than a helical winding direction of the bridge members 160 of a different bridge section 150. For example, the helical winding direction of some bridge members 160 of one bridge section 150 can be dextrorotatory and the helical winding direction of the bridge members 160 of a different bridge section 150 can be levorotatory. The helical winding direction within any given bridge section 150 can be different than the helical winding direction of any adjacent bridge section 150. For example, alternating bridge sections 150 along a longitudinal length of the expandable device 100 can have alternating helical winding directions relative to each other. When the expandable device 100 is extended longitudinally, the bridge members 160 of the bridge sections 150 can straighten relative to the longitudinal axis, causing the connector sections 110 to rotate about the axis in different directions. This allows the extreme ends of the expandable device 100 to rotate relative to each other less than they would if the bridge members 160 of every bridge section 150 were wound in the same helical direction, or not at all.
According to some embodiments, a bridge gap 162 is a distance between a pair of adjacent bridge members 160. The bridge gap 162 can be measured across parallel portions of pairs of adjacent bridge members 160. The bridge gap 162 can be the same (e.g., uniform) or different among different pairs of bridge members 160 within a single bridge section 150. The bridge gap 162 can be the same/uniform or different among different bridge sections 150 of a single device 100. The bridge gap 162 can be 1 to 250 for example greater than 100 μm.
According to some embodiments, the bridge members 160 form a pitch angle 164 with respect to a line that is orthogonal to the longitudinal axis of the expandable device 100. The pitch angle 164 can be the same/uniform or different for different bridge members 160 within a single bridge section 150. The pitch angle 164 can be the same/uniform or different among different bridge sections 150 of a single device 100. The pitch angle 164 can be 10° to 60°, for example 19°.
According to some embodiments, an apex gap 132 is a distance between a pair of adjacent apices 130 on a same longitudinal side of a connector section 110. The apex gap 132 can be measured as orthogonal to a longitudinal axis of the expandable device 100. The apex gap 132 can be the same/uniform or different among different pairs of apices 130 within a single connector section 110. The apex gap 132 can be the same/uniform or different among different connector sections 110 of a single device 100. The apex gap 132 can be 10 to 450 μm, for example 300 μm.
According to some embodiments, a connector section length 112 is a longitudinal distance between opposing longitudinal sides of a connector section 110 (e.g., between a pair of bridge sections 150). The connector section length 112 can be measured as parallel to a longitudinal axis of the expandable device 100. The connector section length 112 can be the same/uniform or different among different connector sections 110 of a single device 100. The connector section length 112 can be 10 to 450 μm, for example 300 μm.
According to some embodiments, a bridge section length 152 is a longitudinal distance between opposing longitudinal sides of a bridge section 150 (e.g., between a pair of connector sections 110). The bridge section length 152 can be measured as parallel to a longitudinal axis of the expandable device 100. The bridge section length 152 can be the same/uniform or different among different bridge sections 150 of a single device 100. The bridge section length 152 can be 500 to 4500 μm, for example 1,100 μm.
According to some embodiments, some or all of the bridge members 160 and/or some or all of the connector struts 120 can comprise a radiopaque marker. The radiopaque marker can be disposed on a substantially straight section of a bridge member 160 and/or a connector strut 120, so the radiopaque marker is predominantly not subject to bending or flexing. For example, the radiopaque marker(s) can be disposed a distance away from an apex 130. The radiopaque marker(s) can be formed on the bridge members 160 and/or the connector struts 120 by a process that is the same or different than a process used to form the bridge members 160 and/or the connector struts 120, which are discussed further herein.
According to some embodiments, the expandable device 100 can provide a porosity that is the range of 5%-95%. The cells of the expandable device 100 can provide a pore size that is between 5 and 450 μm. A pore size can be measured via a maximum inscribed circle technique.
According to some embodiments, a thickness of the connector struts 120 and/or the bridge members 160 can be 5 to 50 μm, for example 50 μm. According to some embodiments, a width of the connector struts 120 and/or the bridge members 160 can be 5 to 50 μm, for example 50 μm.
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An expandable device may be formed, for example, by laser cutting a preformed tube or sheet, by interconnecting components (e.g., by laser welding), by vapor deposition techniques, or combinations thereof. The expandable device can be formed using known flexible materials such as nitinol, stainless steel, cobalt-chromium alloys, Elgiloy, magnesium alloys, tungsten, tantalum, platinum, or combinations thereof.
According to some embodiments, an expandable device can be formed by a photolithography process. A substrate can be provided with a base for supporting the formation of the expandable device. The base (e.g., copper) can be used temporarily as a buffer between the substrate and a primary material used to form the expandable device. After the base is provided on the substrate, the primary material is provided thereon, for example by vapor deposition. The primary material can be provided as a thin film of substantially uniform thickness. Portions of the primary material can be removed to form the structure of the expandable device. For example, a photomask, based on a strut pattern, can be used to selectively expose portions of the primary material to light and etch the primary material into the desired shape for the expandable device. Alternatively or in combination, a chemical agent can be used to remove the portions of the primary material that are not protected by a photoresist. The base can then be eroded to separate the expandable device from the substrate. The expandable device can be further treated to form a desired shape (e.g., tubular) and have the desired heat set and/or shape memory properties.
According to some embodiments, an expandable device can be formed by a laser cutting process. The expandable device may be formed by cutting a pattern of struts on a tube or on a flat sheet and then rolling the flat sheet into a generally tube-like or coiled shape. The expandable device in a generally tube-like or coiled shape can be circumferentially continuous or discontinuous. Where the expandable device is circumferentially discontinuous, portions of the expandable device can overlap in certain states.
As mentioned elsewhere herein, the present disclosure also includes methods of treating a vascular condition, such as an aneurysm, with any of the embodiments of the expandable devices disclosed herein. The expandable device could be deployed across the neck of an aneurysm and its flow-diverting properties employed to impede blood flow between the aneurysm and the parent vessel, cause the blood inside the aneurysm to thrombose, and lead to healing of the aneurysm.
In order to implant any of the expandable devices disclosed herein, the expandable device can be mounted in a delivery system. Generally, the delivery system can comprise an elongate core member that supports or contains the expandable device, and both components can be slidably received in a lumen of a microcatheter or other elongate sheath for delivery to any region to which the distal opening of the microcatheter can be advanced. The core member is employed to advance the expandable device through the microcatheter and out the distal end of the microcatheter so that the expandable device is allowed to self-expand into place in the blood vessel, across an aneurysm or other treatment location. Accordingly, a vascular treatment apparatus can comprise a delivery system, such as any of the delivery systems described herein, and an expandable device, such as any of the expandable devices described herein, mounted in the delivery system.
A treatment procedure can begin with obtaining percutaneous access to the patient's arterial system, typically via a major blood vessel in a leg or arm. A guidewire can be placed through the percutaneous access point and advanced to the treatment location, which can be in an intracranial artery, or any neurovascular artery, peripheral artery or coronary artery. (As configured for neurovascular use, any of the expandable devices disclosed herein can have a diameter of 2-8 mm in the relaxed state or the expanded state; expandable devices used in the peripheral or coronary vasculature can have a diameter of 1-20 mm in the relaxed state or the expanded state.) The microcatheter is then advanced over the guidewire to the treatment location and situated so that a distal open end of the guidewire is adjacent to the treatment location. The guidewire can then be withdrawn from the microcatheter and the core member, together with the expandable device mounted thereon or supported thereby, can be advanced through the microcatheter and out the distal end thereof. The expandable device can then self-expand into apposition with the inner wall of the blood vessel. Where an aneurysm is being treated, the expandable device is placed across the neck of the aneurysm so that a sidewall of the expandable device separates the interior of the aneurysm from the lumen of the parent artery. Once the expandable device has been placed, the core member and microcatheter are removed from the patient. The expandable device sidewall can now perform a flow-diverting function on the aneurysm, thrombosing the blood in the aneurysm and leading to healing of the aneurysm.
The foregoing description is provided to enable a person skilled in the art to practice the various configurations described herein. While the subject technology has been particularly described with reference to the various figures and configurations, it should be understood that these are for illustration purposes only and should not be taken as limiting the scope of the subject technology.
There may be many other ways to implement the subject technology. Various functions and elements described herein may be partitioned differently from those shown without departing from the scope of the subject technology. Various modifications to these configurations will be readily apparent to those skilled in the art, and generic principles defined herein may be applied to other configurations. Thus, many changes and modifications may be made to the subject technology, by one having ordinary skill in the art, without departing from the scope of the subject technology.
A phrase such as “an aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. An aspect may provide one or more examples of the disclosure. A phrase such as “an aspect” may refer to one or more aspects and vice versa. A phrase such as “an embodiment” does not imply that such embodiment is essential to the subject technology or that such embodiment applies to all configurations of the subject technology. A disclosure relating to an embodiment may apply to all embodiments, or one or more embodiments. An embodiment may provide one or more examples of the disclosure. A phrase such “an embodiment” may refer to one or more embodiments and vice versa. A phrase such as “a configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A configuration may provide one or more examples of the disclosure. A phrase such as “a configuration” may refer to one or more configurations and vice versa.
It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplifying approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Some of the steps may be performed simultaneously. Various methods are disclosed presenting elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
Furthermore, to the extent that the term “include,” “have,” or the like is used herein, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim.
A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. All structural and functional equivalents to the elements of the various configurations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the subject technology. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description.
While certain aspects and embodiments of the subject technology have been described, these have been presented by way of example only, and are not intended to limit the scope of the subject technology. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms without departing from the spirit thereof. The numbered clauses and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the subject technology.
The present application is a divisional of U.S. application Ser. No. 15/469,324, filed Mar. 24, 2017, which claims the benefit of and priority to U.S. Provisional Patent Application No. 62/313,055, filed Mar. 24, 2016, both of which are incorporated herein by reference in their entirety.
Number | Date | Country | |
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62313055 | Mar 2016 | US |
Number | Date | Country | |
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Parent | 15469324 | Mar 2017 | US |
Child | 16288894 | US |