Patent Application
20220249098
Not applicable.
Embodiments of devices and methods herein are directed to blocking a flow of fluid through a tubular vessel or into a small interior chamber of a saccular cavity or vascular defect within a mammalian body. More specifically, embodiments herein are directed to devices and methods for treatment of a vascular defect of a patient including some embodiments directed specifically to the treatment of cerebral aneurysms of patients.
The mammalian circulatory system is comprised of a heart, which acts as a pump, and a system of blood vessels which transport the blood to various points in the body. Due to the force exerted by the flowing blood on the blood vessel the blood vessels may develop a variety of vascular defects. One common vascular defect known as an aneurysm results from the abnormal widening of the blood vessel. Typically, vascular aneurysms are formed as a result of the weakening of the wall of a blood vessel and subsequent ballooning and expansion of the vessel wall. If, for example, an aneurysm is present within an artery of the brain, and the aneurysm should burst with resulting cranial hemorrhaging, death could occur.
Surgical techniques for the treatment of cerebral aneurysms typically involve a craniotomy requiring creation of an opening in the skull of the patient through which the surgeon can insert instruments to operate directly on the patient's brain. For some surgical approaches, the brain must be retracted to expose the parent blood vessel from which the aneurysm arises. Once access to the aneurysm is gained, the surgeon places a clip across the neck of the aneurysm thereby preventing arterial blood from entering the aneurysm. Upon correct placement of the clip the aneurysm will be obliterated in a matter of minutes. Surgical techniques may be effective treatment for many aneurysms. Unfortunately, surgical techniques for treating these types of conditions include major invasive surgical procedures which often require extended periods of time under anesthesia involving high risk to the patient. Such procedures thus require that the patient be in generally good physical condition in order to be a candidate for such procedures.
Various alternative and less invasive procedures have been used to treat cerebral aneurysms without resorting to major surgery. One approach to treating aneurysms without the need for invasive surgery involves the placement of sleeves or stents into the vessel and across the region where the aneurysm occurs. Such devices maintain blood flow through the vessel while reducing blood pressure applied to the interior of the aneurysm. Certain types of stents are expanded to the proper size by inflating a balloon catheter, referred to as balloon expandable stents, while other stents are designed to elastically expand in a self-expanding manner. Some stents are covered typically with a sleeve of polymeric material called a graft to form a stent-graft. Stents and stent-grafts are generally delivered to a preselected position adjacent a vascular defect through a delivery catheter. In the treatment of cerebral aneurysms, covered stents or stent-grafts have seen very limited use due to the likelihood of inadvertent occlusion of small perforator vessels that may be near the vascular defect being treated.
In addition, current uncovered stents are generally not sufficient as a stand-alone treatment. In order for stents to fit through the microcatheters used in small cerebral blood vessels, their density is usually reduced such that when expanded there is only a small amount of stent structure bridging the aneurysm neck. Thus, they do not block enough flow to cause clotting of the blood in the aneurysm and are thus generally used in combination with vaso-occlusive devices, such as the coils discussed above, to achieve aneurysm occlusion.
Some procedures involve the delivery of embolic or filling materials into an aneurysm. The delivery of such vaso-occlusion devices or materials may be used to promote hemostasis or fill an aneurysm cavity entirely. Vaso-occlusion devices may be placed within the vasculature of the human body, typically via a catheter, either to block the flow of blood through a vessel with an aneurysm through the formation of an embolus or to form such an embolus within an aneurysm stemming from the vessel. A variety of implantable, coil-type vaso-occlusion devices are known. The coils of such devices may themselves be formed into a secondary coil shape, or any of a variety of more complex secondary shapes. Vaso-occlusive coils are commonly used to treat cerebral aneurysms but suffer from several limitations including poor packing density, compaction due to hydrodynamic pressure from blood flow, poor stability in wide-necked aneurysms, and complexity and difficulty in the deployment thereof as most aneurysm treatments with this approach require the deployment of multiple coils. Coiling is less effective at treating certain physiological conditions, such as wide neck cavities (e.g. wide neck aneurysms) because there is a greater risk of the coils migrating out of the treatment site.
A number of aneurysm neck bridging devices with defect spanning portions or regions have been attempted, however, none of these devices have had a significant measure of clinical success or usage. A major limitation in their adoption and clinical usefulness is the inability to position the defect spanning portion to assure coverage of the neck. Existing stent delivery systems that are neurovascular compatible (i.e. deliverable through a microcatheter and highly flexible) do not have the necessary rotational positioning capability. Another limitation of many aneurysm bridging devices described in the prior art is the poor flexibility. Cerebral blood vessels are tortuous, and a high degree of flexibility is required for effective delivery to most aneurysm locations in the brain.
What has been needed are devices and methods for delivery and use in small and tortuous blood vessels that can substantially block the flow of blood into an aneurysm, such as a cerebral aneurysm, with a decreased risk of inadvertent aneurysm rupture or blood vessel wall damage. In addition, what has been needed are methods and devices suitable for blocking blood flow in cerebral aneurysms over an extended period of time without a significant risk of deformation, compaction or dislocation.
Intrasaccular occlusive devices are part of a newer type of occlusion device used to treat various intravascular conditions including aneurysms. They are often more effective at treating these wide neck conditions, or larger treatment areas. The intrasaccular devices comprise a structure which sits within the aneurysm and provides an occlusive effect at the neck of the aneurysm to help limit blood flow into the aneurysm. The rest of the device comprises a relatively conformable structure that sits within the aneurysm helping to occlude all or a portion of the aneurysm. Intrasaccular devices typically conform to the shape of the treatment site. These devices also occlude the cross section of the neck of the treatment site/aneurysm, thereby promoting clotting and causing thrombosis and closing of the aneurysm over time.
These intrasaccular devices are difficult to design for various reasons. For neurovascular aneurysms, these intrasaccular devices are particularly small and any projecting structures from the intrasaccular device can prod into the vessel or tissue, causing additional complications. In larger aneurysms, there is a risk of compaction where the intrasaccular device can migrate into the aneurysm and leave the neck region. There is a need for an intrasaccular device that addresses these issues.
An intrasaccular occlusion device is described that is used to treat a variety of conditions, including aneurysms and neurovascular aneurysms. For intrasaccular devices, it is often beneficial to have good flow disruption at the neck of the aneurysm to limit the flow of blood into the aneurysm, good proximal stiffness to augment proximal anchoring retention and reduce the risk of device migration during treatment, and good ability to conform to a shape of a treatment site to augment the occlusive benefit of the device. The following embodiments described and presented herein utilize one or more of these factors in order to increase the effectiveness of an intrasaccular device.
In one embodiment, the occlusion device comprises a mesh of braided wires where the mesh of braided wires is gathered into retention structures at the proximal and distal ends of the device. The retention structure at the distal end of the device projects inwardly within the occlusion device so as to not project outwardly from the device.
In one embodiment, the retention structure comprises a hub or marker band where the wires are attached to the retention structure so as to provide a fixed meeting point for the ends of the wires.
In one embodiment, the distal retention structure is recessed within the distal part of the occlusion device and the distal ends of the wires are attached to the distal retention structure so as to form a distal recess comprised of a distal portion of the wires.
In one embodiment, a multiple layer occlusion device is described. A first layer comprises the length of the occlusion device and a second layer comprises only a proximal section of the occlusion device so as to augment the flow-disruptive and/or occlusive effect along the proximal section of the device. The first layer utilizes a distal retention structure that projects inwardly within the occlusion device and the wires comprising the first layer are attached to the distal retention structure.
In one embodiment, a multiple layer occlusion device is described. A first layer comprises the length of the occlusion device and a second layer comprises only a proximal section of the occlusion device so as to augment the flow-disruptive and/or occlusive effect along the proximal section of the device. The proximal, dual layer portion of the device has a variable height so as to customize the portion of the occlusion device having the augmented occlusive effect.
In one embodiment, a multiple layer occlusion device is described. A first layer comprises the length of the occlusion device and a second layer comprises only a proximal section of the occlusion device so as to augment the flow-disruptive and/or occlusive effect along the proximal section of the device. There is a distal retention structure near the distal end of the device, a proximal retention structure near a proximal end of the device, and a third retention structure binding the distal portion of the secondary augmented occlusion layer. The distal retention structure and the third retention structure are connected to allow the occlusive device height to vary based on the geometry of the treated vascular condition.
In one embodiment, a multiple layer occlusion device is described. A first layer comprises the length of the occlusion device and a second layer comprises only a proximal section of the occlusion device so as to augment the flow-disruptive and/or occlusive effect along the proximal section of the device. In one embodiment, the second layer is a secondary mesh. In one embodiment, the secondary layer is a skeletal wire structure to provide radial stiffness along the proximal portion of the occlusion device.
In another embodiment, a device for treatment of a patient's cerebral aneurysm is described. The device includes a first permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, the expanded state having a proximal portion, a distal portion, and an interior cavity, wherein each of the plurality of filaments has a proximal end and a distal end, wherein the proximal ends of each of the plurality of filaments are gathered in a proximal hub or marker band and the distal ends of each of the plurality of filaments are gathered by a first distal hub or marker band that is located in the interior cavity; and a second permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, wherein at least a portion of the second permeable shell is in contact with the proximal portion of the first permeable shell, wherein each of the plurality of filaments of the second permeable shell has a proximal end and a distal end, wherein the distal ends of each of the plurality of filaments of the second permeable shell are gathered in a second distal hub or marker band, and wherein the proximal ends of each of the plurality of filaments of the second permeable shell are gathered in the proximal hub or marker band with the proximal ends of each of the plurality of filaments of the first permeable shell. A length of the expanded state of the second permeable shell is smaller than a length of the expanded state of the first permeable shell. In one embodiment, the first and second distal hubs or marker bands may be coupled together.
In another embodiment, a method for treating a cerebral aneurysm having an interior cavity and a neck is described. The method includes the step of advancing an implant in a microcatheter to a region of interest in a cerebral artery, wherein the implant comprises a first permeable shell including a radially constrained elongated state configured for delivery within a lumen of the microcatheter, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, the expanded state having a proximal portion, a distal portion, an dan interior cavity, wherein each of the plurality of filaments has a proximal end and a distal end, wherein the proximal ends of each of the plurality of filaments are gathered in a proximal hub or marker band and the distal ends of each of the plurality of filaments are gathered by a first distal hub or marker band located in the interior cavity of the first permeable shell; and a second permeable shell including a radially constrained elongated state configured for delivery within the lumen of the microcatheter, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, wherein at least a portion of the second permeable shell is in contact with the proximal portion of the first permeable shell, wherein each of the plurality of filaments has a proximal end and a distal end, wherein the distal ends of each of the plurality of filaments of the second permeable shell are gathered in a second distal hub or marker band, and wherein the proximal ends of each of the plurality of filaments of the second permeable shell are gathered in the proximal hub or marker band with the proximal ends of each of the plurality of filaments of the first permeable shell. A length of the expanded state of the second permeable shell is smaller than a length of the expanded state of the first permeable shell. The implant is then deployed within the cerebral aneurysm, wherein the first and second permeable shells expand to each of their expanded states in the interior cavity of the aneurysm. The microcatheter is then withdrawn from the region of interest after deploying the implant.
In another embodiment, a device for treatment of a patient's cerebral aneurysm is described. The device includes a first permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, the expanded state having a proximal portion, a distal portion, and an interior cavity, wherein each of the plurality of filaments has a proximal end and a distal end, wherein the proximal ends of each of the plurality of filaments are gathered in a proximal hub or marker band and the distal ends of each of the plurality of filaments are gathered by a first distal hub or marker band that is located in the interior cavity; and a second permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, wherein each of the plurality of filaments of the second permeable shell has a proximal end and a distal end, wherein the distal ends of each of the plurality of filaments of the second permeable shell are gathered in a second distal hub or marker band, and wherein the proximal ends of each of the plurality of filaments of the second permeable shell are gathered in the proximal hub or marker band with the proximal ends of each of the plurality of filaments of the first permeable shell. The first distal hub or marker band and the second distal hub or marker band are coupled together.
In another embodiment, a method for treating a cerebral aneurysm having an interior cavity and a neck is described. The method includes the step of advancing an implant in a microcatheter to a region of interest in a cerebral artery, wherein the implant comprises a first permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, the expanded state having a proximal portion, a distal portion, and an interior cavity, wherein each of the plurality of filaments has a proximal end and a distal end, wherein the proximal ends of each of the plurality of filaments are gathered in a proximal hub or marker band and the distal ends of each of the plurality of filaments are gathered by a first distal hub or marker band that is located in the interior cavity; and a second permeable shell including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of elongate filaments that are woven together to form a mesh, wherein each of the plurality of filaments of the second permeable shell has a proximal end and a distal end, wherein the distal ends of each of the plurality of filaments of the second permeable shell are gathered in a second distal hub or marker band, and wherein the proximal ends of each of the plurality of filaments of the second permeable shell are gathered in the proximal hub or marker band with the proximal ends of each of the plurality of filaments of the first permeable shell. The first distal hub or marker band and the second distal hub or marker band are coupled together. The implant is then deployed within the cerebral aneurysm, wherein the first and second permeable shells expand to each of their expanded states in the interior cavity of the aneurysm. The microcatheter is then withdrawn from the region of interest after deploying the implant.
In any of the embodiments described, the first permeable shell may be less stiff or softer than the second permeable shell such that the distal portion of the device has a soft, deformable distal end and distal region. The filaments making up the first permeable shell may have a smaller diameter than the filaments making up the second permeable shell. The filaments making up the first permeable shell may have a diameter of between about 0.0003″ and about 0.00075.” The filaments making up the second permeable shell may have a diameter of between about 0.0015″ and about 0.004.″ The first permeable shell may be made from a larger number of filaments woven tighter than the second permeable shell. The first permeable shell may be made from about 36 to about 360 filaments woven together. The second permeable shell may be made from about 4 to about 48 filaments woven together.
In any of the embodiments described, the first permeable shell may have an inverted distal end. The filaments woven together to form the first permeable shell each have a proximal and distal end. The filaments extend from a proximal end to a distal end of the first permeable shell and further extends proximally back towards the proximal end of the first permeable shell, such that the distal ends of each of the plurality of filaments of the first permeable shell are located in the interior cavity of the first permeable shell and the band holding the distal ends of the filaments together is located in the interior cavity of the first permeable shell. The distal hub or marker band of the first permeable shell may be coupled to the distal hub or marker band of the second permeable shell. The distal hubs or marker bands may be coupled together through a tether, wire, or mesh. The proximal and distal hubs or marker bands may be tubular bands.
In any of the embodiments described, the second permeable shell may sit in the proximal section of the device. The second permeable shell may sit in an interior cavity of the first permeable shell such that at least a portion of the outer surface of the second permeable shell is in contact with the inner surface of a proximal section of the first permeable shell. The second permeable shell may be attached to the first permeable shell by welding, adhesive, or mechanical ties. The second permeable shell may be attached to the first permeable shell through the proximal hub or marker band. The proximal ends of the filaments of the second permeable shell and the proximal ends of the filaments of the first permeable shell may all be gathered together in a single hub or marker band.
In any of the embodiments described, the length of the expanded state of the second permeable shell may be between about 10% and about 70%, alternatively between about 10% and about 60%, alternatively between about 10% and about 50%, alternatively between about 10% and about 40%, alternatively between about 10% and about 30% of the length of the expanded state of the first permeable shell.
In another embodiment, a device for treatment of a patient's cerebral aneurysm is described. The device includes a first permeable shell including a first end, a second end, a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of filaments that are woven together to form a mesh, wherein each of the plurality of filaments has a first end and a second end, wherein each of the plurality of filaments starts at the first end of the first permeable shell, extends to the second end of the first permeable shell, and extends back to the first end of the first permeable shell, and wherein the first and second ends of each of the plurality of filaments are gathered in a hub or marker band at the first end of the first permeable shell; and a support structure including a radially constrained elongated state configured for delivery within a catheter lumen, an expanded state, and a plurality of scaffolding filaments that are associated with a portion of the first permeable shell that includes the first end of the first permeable shell. In one embodiment, each of the plurality of scaffolding filaments has a diameter that is larger than a diameter of each of the plurality of elongate filaments of the first permeable shell.
In another embodiment, a method for treating a cerebral aneurysm having an interior cavity and a neck is described. The method includes the step of advancing an implant in a microcatheter to a region of interest in a cerebral artery, wherein the implant comprises a first permeable shell including a first end, a second end, a radially constrained elongated state configured for delivery within a lumen of the microcatheter, an expanded state, and a plurality of filaments that are woven together to form a mesh, wherein each of the plurality of filaments has a first end and a second end, wherein each of the plurality of filaments starts at the first end of the first permeable shell, extends to the second end of the first permeable shell, and extends back to the first end of the first permeable shell, and wherein the first and second ends of each of the plurality of filaments are gathered in a hub or marker band at the first end of the first permeable shell; and a support structure including a radially constrained elongated state configured for delivery within the lumen of the microcatheter, an expanded state, and a plurality of scaffolding filaments that are associated with a portion of the first permeable shell that includes the first end of the first permeable shell. In one embodiment, each of the plurality of scaffolding filaments has a diameter that is larger than a diameter of each of the plurality of filaments of the first permeable shell. The implant is then deployed within the cerebral aneurysm, wherein the permeable shell and the support structure expand to each of their expanded states in the interior cavity of the aneurysm. The microcatheter is then withdrawn from the region of interest after deploying the implant.
In any of the embodiments described, the support structure is coupled to the first permeable shell. The support structure may be coupled to the first permeable shell using welding, adhesive, or mechanical ties. The plurality of scaffolding filaments of the support structure may be woven into the mesh of the first permeable shell.
In any of the embodiments described, the scaffolding filaments may have a diameter of between about 0.001″ and about 0.004″. The scaffolding filaments may be made from a shape memory alloy such as nitinol, or DFT, or combinations thereof. The expanded state of the support structure may have a scalloped shaped open distal end wherein the scaffolding wires extend distally from a proximal end and curve back in a proximal direction to form a curved shape in a distal region. Adjacent scaffolding filaments may be connected together to form the scalloped shape open distal end.
In any of the embodiments described, the support structure has a height between about 10% and about 70% of the height of the first permeable shell.
In any of the embodiments described, the portion of the device that includes the support structure is stiffer than the portion of the device near the distal end that does not include the support structure. The portion of the device that includes the support structure may have a stiffness of at least about 0.001 N/mm. The distal portion of the device that does not include the support structure may have a stiffness or no more than about 0.020 N/mm.
In any of the embodiments described, both of the permeable shell and the support structure are self-expandable.
In any of the embodiments described, the permeable shell may have an inverted distal end. The filaments woven together to form the permeable shell each have a proximal and distal end. The distal end of the filaments extend from a proximal end to a distal end of the permeable shell and further extends proximally back to the proximal end of the permeable shell, such that the proximal and distal ends of each of the plurality of filaments of the permeable shell are gathered together in a band at the proximal end of the permeable shell. Thus, the device has a cavity (e.g., a conical shaped cavity or a cylindrical shaped cavity), extending from the distal end and terminating at the proximal band at the proximal end of the permeable shell.
Discussed herein are devices and methods for the treatment of vascular defects that are suitable for minimally invasive deployment within a patient's vasculature, and particularly, within the cerebral vasculature of a patient. For such embodiments to be safely and effectively delivered to a desired treatment site and effectively deployed, some device embodiments may be configured for collapse to a low profile constrained state with a transverse dimension suitable for delivery through an inner lumen of a microcatheter and deployment from a distal end thereof. Embodiments of these devices may also maintain a clinically effective configuration with sufficient mechanical integrity once deployed so as to withstand dynamic forces within a patient's vasculature over time that may otherwise result in compaction of a deployed device. It may also be desirable for some device embodiments to acutely occlude a vascular defect of a patient during the course of a procedure in order to provide more immediate feedback regarding success of the treatment to a treating physician.
Intrasaccular occlusive devices that include a permeable shell formed from a woven or braided mesh have been described in US 2017/0095254, US 2016/0249934, US 2016/0367260, US 2016/0249937, and US 2018/0000489, all of which are hereby expressly incorporated by reference in their entirety for all purposes.
Some embodiments are particularly useful for the treatment of cerebral aneurysms by reconstructing a vascular wall so as to wholly or partially isolate a vascular defect from a patient's blood flow. Some embodiments may be configured to be deployed within a vascular defect to facilitate reconstruction, bridging of a vessel wall or both in order to treat the vascular defect. For some of these embodiments, the permeable shell of the device may be configured to anchor or fix the permeable shell in a clinically beneficial position. For some embodiments, the device may be disposed in whole or in part within the vascular defect in order to anchor or fix the device with respect to the vascular structure or defect. The permeable shell may be configured to span an opening, neck or other portion of a vascular defect in order to isolate the vascular defect, or a portion thereof, from the patient's nominal vascular system in order allow the defect to heal or to otherwise minimize the risk of the defect to the patient's health.
For some or all of the embodiments of devices for treatment of a patient's vasculature discussed herein, the permeable shell may be configured to allow some initial perfusion of blood through the permeable shell. The porosity of the permeable shell may be configured to sufficiently isolate the vascular defect so as to promote healing and isolation of the defect, but allow sufficient initial flow through the permeable shell so as to reduce or otherwise minimize the mechanical force exerted on the membrane the dynamic flow of blood or other fluids within the vasculature against the device. For some embodiments of devices for treatment of a patient's vasculature, only a portion of the permeable shell that spans the opening or neck of the vascular defect, sometimes referred to as a defect spanning portion, need be permeable and/or conducive to thrombus formation in a patient's bloodstream. For such embodiments, that portion of the device that does not span an opening or neck of the vascular defect may be substantially non-permeable or completely permeable with a pore or opening configuration that is too large to effectively promote thrombus formation.
In general, it may be desirable in some cases to use a hollow, thin walled device with a permeable shell of resilient material that may be constrained to a low profile for delivery within a patient. Such a device may also be configured to expand radially outward upon removal of the constraint such that the shell of the device assumes a larger volume and fills or otherwise occludes a vascular defect within which it is deployed. The outward radial expansion of the shell may serve to engage some or all of an inner surface of the vascular defect whereby mechanical friction between an outer surface of the permeable shell of the device and the inside surface of the vascular defect effectively anchors the device within the vascular defect. Some embodiments of such a device may also be partially or wholly mechanically captured within a cavity of a vascular defect, particularly where the defect has a narrow neck portion with a larger interior volume. In order to achieve a low profile and volume for delivery and be capable of a high ratio of expansion by volume, some device embodiments include a matrix of woven or braided filaments that are coupled together by the interwoven structure so as to form a self-expanding permeable shell having a pore or opening pattern between couplings or intersections of the filaments that is substantially regularly spaced and stable, while still allowing for conformity and volumetric constraint.
As used herein, the terms woven and braided are used interchangeably to mean any form of interlacing of filaments to form a mesh structure. In the textile and other industries, these terms may have different or more specific meanings depending on the product or application such as whether an article is made in a sheet or cylindrical form. For purposes of the present disclosure, these terms are used interchangeably.
For some embodiments, three factors may be critical for a woven or braided wire occlusion device for treatment of a patient's vasculature that can achieve a desired clinical outcome in the endovascular treatment of cerebral aneurysms. We have found that for effective use in some applications, it may be desirable for the implant device to have sufficient radial stiffness for stability, limited pore size for near-complete acute (intra-procedural) occlusion and a collapsed profile which is small enough to allow insertion through an inner lumen of a microcatheter. A device with a radial stiffness below a certain threshold may be unstable and may be at higher risk of embolization in some cases. Larger pores between filament intersections in a braided or woven structure may not generate thrombus and occlude a vascular defect in an acute setting and thus may not give a treating physician or health professional such clinical feedback that the flow disruption will lead to a complete and lasting occlusion of the vascular defect being treated. Delivery of a device for treatment of a patient's vasculature through a standard microcatheter may be highly desirable to allow access through the tortuous cerebral vasculature in the manner that a treating physician is accustomed. A detailed discussion of radial stiffness, pore size, and the necessary collapsed profile can be found in US 2017/0095254, which was previously expressly incorporated by reference in its entirety.
As has been discussed, some embodiments of devices for treatment of a patient's vasculature call for sizing the device which approximates (or with some over-sizing) the vascular site dimensions to fill the vascular site. One might assume that scaling of a device to larger dimensions and using larger filaments would suffice for such larger embodiments of a device. However, for the treatment of brain aneurysms, the diameter or profile of the radially collapsed device is limited by the catheter sizes that can be effectively navigated within the small, tortuous vessels of the brain. Further, as a device is made larger with a given or fixed number of resilient filaments having a given size or thickness, the pores or openings between junctions of the filaments are correspondingly larger. In addition, for a given filament size the flexural modulus or stiffness of the filaments and thus the structure decrease with increasing device dimension. Flexural modulus may be defined as the ratio of stress to strain. Thus, a device may be considered to have a high flexural modulus or be stiff if the strain (deflection) is low under a given force. A stiff device may also be said to have low compliance.
To properly configure larger size devices for treatment of a patient's vasculature, it may be useful to model the force on a device when the device is deployed into a vascular site or defect, such as a blood vessel or aneurysm, that has a diameter or transverse dimension that is smaller than a nominal diameter or transverse dimension of the device in a relaxed unconstrained state. As discussed, it may be advisable to “over-size” the device in some cases so that there is a residual force between an outside surface of the device and an inside surface of the vascular wall. The inward radial force on a device 10 that results from over-sizing is illustrated schematically in
Deflection of Beam=5FL4/384 El
Thus, as the size of the device increases and L increases, the compliance increases substantially. Accordingly, an outward radial force exerted by an outside surface of the filaments 14 of the device 10 against a constraining force when inserted into a vascular site such as blood vessel or aneurysm is lower for a given amount of device compression or over-sizing. This force may be important in some applications to assure device stability and to reduce the risk of migration of the device and potential distal embolization.
In some embodiments, a combination of small and large filament sizes may be utilized to make a device with a desired radial compliance and yet have a collapsed profile which is configured to fit through an inner lumen of commonly used microcatheters. A device fabricated with even a small number of relatively large filaments 14 can provide reduced radial compliance (or increased stiffness) compared to a device made with all small filaments. Even a relatively small number of larger filaments may provide a substantial increase in bending stiffness due to change in the moment of Inertia that results from an increase in diameter without increasing the total cross sectional area of the filaments. The moment of inertia (I) of a round wire or filament may be defined by the equation:
I=πd
4/64
Since the moment of inertia is a function of filament diameter to the fourth power, a small change in the diameter greatly increases the moment of inertia. Thus, small changes in filament size can have substantial impact on the deflection at a given load and thus the compliance of the device.
Thus, the stiffness can be increased by a significant amount without a large increase in the cross sectional area of a collapsed profile of the device 10. This may be particularly important as device embodiments are made larger to treat large aneurysms. While large cerebral aneurysms may be relatively rare, they present an important therapeutic challenge as some embolic devices currently available to physicians have relatively poor results compared to smaller aneurysms.
As such, some embodiments of devices for treatment of a patient's vasculature may be formed using a combination of filaments 14 with a number of different diameters such as 2, 3, 4, 5 or more different diameters or transverse dimensions. In device embodiments where filaments with two different diameters are used, some larger filament embodiments may have a transverse dimension of about 0.001 inches to about 0.004 inches and some small filament embodiments may have a transverse dimension or diameter of about 0.0004 inches and about 0.0015 inches, more specifically, about 0.0004 inches to about 0.001 inches. The ratio of the number of large filaments to the number of small filaments may be between about 2 and 12 and may also be between about 4 and 8. In some embodiments, the difference in diameter or transverse dimension between the larger and smaller filaments may be less than about 0.004 inches, more specifically, less than about 0.0035 inches, and even more specifically, less than about 0.002 inches.
As discussed above, device embodiments 10 for treatment of a patient's vasculature may include a plurality of wires, fibers, threads, tubes or other filamentary elements that form a structure that serves as a permeable shell. For some embodiments, a globular shape may be formed from such filaments by connecting or securing the ends of a tubular braided structure. For such embodiments, the density of a braided or woven structure may inherently increase at or near the ends where the wires or filaments 14 are brought together and decrease at or near a middle portion 30 disposed between a proximal end 32 and distal end 34 of the permeable shell 40. For some embodiments, an end or any other suitable portion of a permeable shell 40 may be positioned in an opening or neck of a vascular defect such as an aneurysm for treatment. As such, a braided or woven filamentary device with a permeable shell may not require the addition of a separate defect spanning structure having properties different from that of a nominal portion of the permeable shell to achieve hemostasis and occlusion of the vascular defect. Such a filamentary device may be fabricated by braiding, weaving or other suitable filament fabrication techniques. Such device embodiments may be shape set into a variety of three-dimensional shapes such as discussed herein.
Referring to
As shown in
As such, once the device 10 is deployed, any blood flowing through the permeable shell may be slowed to a velocity below the thrombotic threshold velocity and thrombus will begin to form on and around the openings in the permeable shell 40. Ultimately, this process may be configured to produce acute occlusion of the vascular defect within which the device 10 is deployed. For some embodiments, at least the distal end of the permeable shell 40 may have a reverse bend in an everted configuration such that the secured distal ends 62 of the filaments 14 are withdrawn axially within the nominal permeable shell structure or contour in the expanded state. For some embodiments, the proximal end of the permeable shell further includes a reverse bend in an everted configuration such that the secured proximal ends 60 of the filaments 14 are withdrawn axially within the nominal permeable shell structure 40 in the expanded state. As used herein, the term everted may include a structure that is everted, partially everted and/or recessed with a reverse bend as shown in the device embodiment of
The elongate resilient filaments 14 of the permeable shell 40 may be secured relative to each other at proximal ends 60 and distal ends 62 thereof by one or more methods including welding, soldering, adhesive bonding, epoxy bonding or the like. In addition to the ends of the filaments being secured together, a distal hub 66 may also be secured to the distal ends 62 of the thin filaments 14 of the permeable shell 40 and a proximal hub 68 secured to the proximal ends 60 of the thin filaments 14 of the permeable shell 40. The proximal hub 68 may include a cylindrical member that extends proximally beyond the proximal ends 60 of the thin filaments so as to form a cavity 70 within a proximal portion of the proximal hub 68. The proximal cavity 70 may be used for holding adhesives such as epoxy, solder or any other suitable bonding agent for securing an elongate detachment tether 72 that may in turn be detachably secured to a delivery apparatus such as is shown in
For some embodiments, the elongate resilient filaments 14 of the permeable shell 40 may have a transverse cross section that is substantially round in shape and be made from a superelastic material that may also be a shape memory metal. The shape memory metal of the filaments of the permeable shell 40 may be heat set in the globular configuration of the relaxed expanded state as shown in
The device 10 may have an everted filamentary structure with a permeable shell 40 having a proximal end 32 and a distal end 34 in an expanded relaxed state. The permeable shell 40 has a substantially enclosed configuration for the embodiments shown. Some or all of the permeable shell 40 of the device 10 may be configured to substantially block or impede fluid flow or pressure into a vascular defect or otherwise isolate the vascular defect over some period of time after the device is deployed in an expanded state. The permeable shell 40 and device 10 generally also has a low profile, radially constrained state, as shown in
Proximal ends 60 of at least some of the filaments 14 of the permeable shell 40 may be secured to the proximal hub 68 and distal ends 62 of at least some of the filaments 14 of the permeable shell 40 are secured to the distal hub 66, with the proximal hub 68 and distal hub 66 being disposed substantially concentric to the longitudinal axis 46 as shown in
Some device embodiments 10 having a braided or woven filamentary structure may be formed using about 10 filaments to about 300 filaments 14, more specifically, about 10 filaments to about 100 filaments 14, and even more specifically, about 60 filaments to about 80 filaments 14. Some embodiments of a permeable shell 40 may include about 70 filaments to about 300 filaments extending from the proximal end 32 to the distal end 34, more specifically, about 100 filaments to about 200 filaments extending from the proximal end 32 to the distal end 34. For some embodiments, the filaments 14 may have a transverse dimension or diameter of about 0.0008 inches to about 0.004 inches. The elongate resilient filaments 14 in some cases may have an outer transverse dimension or diameter of about 0.0005 inch to about 0.005 inch, more specifically, about 0.001 inch to about 0.003 inch, and in some cases about 0.0004 inches to about 0.002 inches. For some device embodiments 10 that include filaments 14 of different sizes, the large filaments 48 of the permeable shell 40 may have a transverse dimension or diameter that is about 0.001 inches to about 0.004 inches and the small filaments 50 may have a transverse dimension or diameter of about 0.0004 inches to about 0.0015 inches, more specifically, about 0.0004 inches to about 0.001 inches. In addition, a difference in transverse dimension or diameter between the small filaments 50 and the large filaments 48 may be less than about 0.004 inches, more specifically, less than about 0.0035 inches, and even more specifically, less than about 0.002 inches. For embodiments of permeable shells 40 that include filaments 14 of different sizes, the number of small filaments 50 of the permeable shell 40 relative to the number of large filaments 48 of the permeable shell 40 may be about 2 to 1 to about 15 to 1, more specifically, about 2 to 1 to about 12 to 1, and even more specifically, about 4 to 1 to about 8 to 1.
The expanded relaxed state of the permeable shell 40, as shown in
For some embodiments, the permeable shell 40 may have a first transverse dimension in a collapsed radially constrained state of about 0.2 mm to about 2 mm and a second transverse dimension in a relaxed expanded state of about 4 mm to about 30 mm. For some embodiments, the second transverse dimension of the permeable shell 40 in an expanded state may be about 2 times to about 150 times the first transverse dimension, more specifically, about 10 times to about 25 times the first or constrained transverse dimension. A longitudinal spacing between the proximal end 32 and distal end 34 of the permeable shell 40 in the relaxed expanded state may be about 25% percent to about 75% percent of the spacing between the proximal end 32 and distal end 34 in the constrained cylindrical state. For some embodiments, a major transverse dimension of the permeable shell 40 in a relaxed expanded state may be about 4 mm to about 30 mm, more specifically, about 9 mm to about 15 mm, and even more specifically, about 4 mm to about 8 mm.
An arced portion of the filaments 14 of the permeable shell 40 may have a sinusoidal-like shape with a first or outer radius 88 and a second or inner radius 90 near the ends of the permeable shell 40 as shown in
The first radius 88 and second radius 90 of the permeable shell 40 may be between about 0.12 mm to about 3 mm for some embodiments. For some embodiments, the distance between the proximal end 32 and distal end 34 may be more than about 60% of the overall length of the expanded permeable shell 40. Thus, the largest longitudinal distance between the inner surfaces may be about 60% to about 90% of the longitudinal length of the outer surfaces or the overall length of device 10. A gap between the hubs 66 and 68 at the proximal end 32 and distal end 34 may allow for the distal hub 66 to flex downward toward the proximal hub 68 when the device 10 meets resistance at the distal end and thus provides longitudinal conformance. The filaments 14 may be shaped such that there are no portions that are without curvature over a distance of more than about 2 mm. Thus, for some embodiments, each filament 14 may have a substantially continuous curvature. This substantially continuous curvature may provide smooth deployment and may reduce the risk of vessel perforation. The distal end 34 may be retracted or everted to a greater extent than the proximal end 32 such that the distal end portion of the permeable shell 40 may be more radially conformal than the proximal end portion.
Conformability of a distal end portion may provide better device conformance to irregular shaped aneurysms or other vascular defects. A convex surface of the device may flex inward forming a concave surface to conform to curvature of a vascular site.
The pore size defined by the largest circular shapes 100 that may be disposed within openings 64 of the braided structure of the permeable shell 40 without displacing or distorting the filaments 14 surrounding the opening 64 may range in size from about 0.005 inches to about 0.01 inches, more specifically, about 0.006 inches to about 0.009 inches, even more specifically, about 0.007 inches to about 0.008 inches for some embodiments. In addition, at least some of the openings 64 formed between adjacent filaments 14 of the permeable shell 40 of the device 10 may be configured to allow blood flow through the openings 64 only at a velocity below a thrombotic threshold velocity. For some embodiments, the largest openings 64 in the permeable shell structure 40 may be configured to allow blood flow through the openings 64 only at a velocity below a thrombotic threshold velocity. As discussed above, the pore size may be less than about 0.016 inches, more specifically, less than about 0.012 inches for some embodiments. For some embodiments, the openings 64 formed between adjacent filaments 14 may be about 0.005 inches to about 0.04 inches.
The following embodiments utilize a secondary structure along an intrasaccular device to provide some benefits—such as increased flow-disruption and/or occlusion along a proximal region of the device, and increased anchoring strength along a proximal region of the device. In some embodiments, increased proximal anchoring strength may provide additional benefits, such as allowing for a softer distal portion that can better conform to the shape of the treatment site.
The distal attachment point represented by the distal hub or marker band 352a is important because the distal portion of the intrasaccular device 310 sits within the aneurysm, toward the “top” or dome of the aneurysm. Any projecting structure can potentially contact the dome of the aneurysm and lead to complications, including rupture. The following embodiments address this issue by utilizing a recessed distal marker structure. In
Going into further detail into
One additional advantage to the secondary internal mesh 322 is that this mesh enhances the occlusive effect of the internal region of the device 340 because this mesh occupies additional space within the treatment site. This enhanced occlusive effect will be noticed in the proximal region where the secondary internal mesh 322 is located, thereby providing augmented occlusion at least along a proximal section of the device 340.
In some embodiments, this multiple layer approach can be adjusted so that the main outer structure comprises one or more layers, and the additional inner secondary structure comprises one or more additional layers. Additional layers will provide more flow-disruptive barriers and lower porosity to further reduce blood flow into the aneurysm or treatment site. The additional layers can also work to augment the occlusive effects of the device, as described above. Much of the potential for additional occlusive layers will be based on the location of the malformation and the relative size, along with the size of the vessel and the associated delivery catheter that will fit the respective vessel. Increasing the amount of overlapped wires, however, makes pushability and deliverability more difficult and increases stiffness. Thus, utilizing more than a two-layer approach may only be feasible for treatment along larger vessels, such as those not in the neurological space. For the neurological space, such as treatment of neurovascular aneurysms or to promote vessel occlusion within neurovascular blood vessels, utilizing one outer layer and one inner layer may be sufficient to occlude blood flow while still providing a deliverable device.
In a dual layer system, the one layer or shell would provide more structural integrity and the radial force required to anchor the device and oppose the walls of the aneurysm while the other layer or shell could function more as a stasis or flow-disruptive layer, providing a smaller pore size for blood and flow stasis. Either the outer 340 or the inner 322 layer could be configured as the structural layer or the stasis layer. Therefore, in one embodiment, the outer layer 340 (e.g., the layer spanning the length of the device 310) functions as the more resilient structural layer while the inner layer 322 (e.g., the inner layer spanning the proximal section of the device) functions as the stasis layer. In another embodiment, the outer layer 340 functions as the stasis layer while the inner layer 322 functions as the more resilient structural layer.
The structural layer may be comprised of about 4-48 wires, alternatively about 8-48 wires, alternatively about 4-44 wires, alternatively about 4-36 wires. The wires in the structural layer may have a diameter of about 0.001″ to about 0.004″, alternatively about 0.001″ to about 0.003″, alternatively about 0.001″ to about 0.002″. The structural layer may have a radial stiffness or a normalized radial stiffness between about 0.005 N/mm and 0.040 N/mm, alternatively between about 0.005 N/mm and 0.025 N/mm, alternatively between about 0.005 N/mm and 0.025 N/mm.
The stasis layer may be comprised of about 36-360 wires, alternatively about 72-216, alternatively about 96-144. The wires in the stasis layer may have a diameter of about 0.0003″ to about 0.00125″, alternatively about 0.0005″ to about 0.001″, alternatively about 0.0006″ to about 0.0009″. The stasis layer may have a radial stiffness or a normalized radial stiffness between about 0.001 N/mm and 0.020 N/mm, alternatively between about 0.001 N/mm and 0.010 N/mm, alternatively between about 0.001 N/mm and 0.005 N/mm.
In addition to the scaffolding structure 422, this embodiment also foregoes the distal hub or marker band attachment concept for the distal ends of the wires of the mesh (as described in the other embodiments above). Instead, the distal ends of the wires or filaments 414 of the mesh occlusive device are pulled proximally back to the proximal end of the device and welded or otherwise attached to the single proximal hub or marker band, thereby creating a middle inverting layer section 436. Thus, the proximal and distal ends of the wires or filaments that are woven together to form permeable shell 440 are both gathered and secured at the proximal end 432 of the device 410. Because the distal ends of the filaments 414 are pulled through the interior cavity of permeable shell 440 and connected at the proximal end of the device 410, no distal wire attachment structure or hub is needed. In this way, the issue with a distal projecting structure that can otherwise contact the dome of the aneurysm is avoided entirely.
The inclusion of middle inverting layer 436 may offer additional advantages, for instance less connection points by having just one common proximal marker connection junction for the various sires comprising the device 410. Furthermore, the mesh layer comprising the length of device 410 can utilize relatively softer wires to promote conformability due to the anchoring force provided by scaffolding wires 422, which can allow device 410 to have some degree of conformability to adopt to the shape of the treatment region.
Alternative embodiments can utilize the scaffolding structure 422 along with the distal hub or marker band configuration of other embodiments. In other words, the scaffolding structure 422 can be further included on other embodiments described earlier in order to augment the proximal retention force of other instrasaccular device embodiments presented so far.
The permeable mesh shell 440 may be comprised of about 4-48 wires, alternatively about 8-48 wires, alternatively about 4-44 wires, alternatively about 4-36 wires. The wires in the structural layer may have a diameter of about 0.0003″ to about 0.00125″, alternatively about 0.0005″ to about 0.001″, alternatively about 0.0006″ to about 0.0009″. The permeable shell may also have filaments made with different materials. For instance, the permeable shell may contain filaments made from nitinol and also contain composite (DFT) filaments. The permeable shell 440 may have a radial stiffness or a normalized radial stiffness between about 0.001 N/mm and 0.020 N/mm, alternatively between about 0.001 N/mm and 0.010 N/mm, alternatively between about 0.001 N/mm and 0.005 N/mm.
The scaffolding structure 422 may include about 4 to about 48 wires, alternatively about 8 to about 48 wires, alternatively about 4 to about 44 wires, alternatively about 4 to about 36 wires. The scaffolding wires may have a diameter of about 0.001″ to about 0.004″, alternatively about 0.001″ to about 0.003″, alternatively about 0.001″ to about 0.002″. The scaffolding wires may have a diameter between about 233.33 and about 220%, alternatively between about 100 and about 200%, alternatively between about 66.67 and about 122% bigger than the diameter of the wires forming the permeable mesh shell 440. The scaffolding wires 422 may be made from nitinol, stainless steel, radiopaque material (e.g., tantalum, platinum, palladium, or gold) or DFT utilizing a radiopaque core and a nitinol outer jacket. The scaffolding structure 422 may have a radial stiffness or a normalized radial stiffness between about 0.005 N/mm and 0.040 N/mm, alternatively between about 0.005 N/mm and 0.025 N/mm, alternatively between about 0.005 N/mm and 0.020 N/mm.
The expanded state of the support structure may have a scalloped shaped open distal end wherein the scaffolding wires or filaments extend distally from a proximal end and curve back in a proximal direction to form a curved shape in a distal region. Adjacent scaffolding filaments may be connected together to form the scalloped shape open distal end.
The scaffolding structure may be located in the proximal portion of the device 410. The proximal section 433 of the permeable shell 410 may have a length that is about ½, alternatively about ¼, of the length of the permeable shell in its expanded state. The proximal section 433 of the permeable shell 410 may comprise the portion beginning at the proximal end 432 and extending to about 20% or less, alternatively about 25% or less, alternatively about 30% or less, alternatively about 33% or less, alternatively about 40% or less, alternatively about 50% or less of the total length of the expanded state of the device 410. The proximal section 433 of the permeable shell 410 may comprise the portion beginning at the proximal end 432 and extending to between about 10% to about 50%, alternatively between about 10% and about 40%, alternatively between about 10% and about 30%, alternatively between about 15% and about 50%, alternatively between about 15% and about 40%, alternatively between about 20% and about 40% of the total length of the expanded state of the device 410.
For some embodiments, the permeable shell 40, 340, 440 or portions thereof may be porous and may be highly permeable to liquids. In contrast to most vascular prosthesis fabrics or grafts which typically have a water permeability below 2,000 ml/min/cm2 when measured at a pressure of 120 mmHg, the permeable shell 40 of some embodiments discussed herein may have a water permeability greater than about 2,000 ml/min/cm2, in some cases greater than about 2,500 ml/min/cm2. For some embodiments, water permeability of the permeable shell 40 or portions thereof may be between about 2,000 and 10,000 ml/min/cm2, more specifically, about 2,000 ml/min/cm2 to about 15,000 ml/min/cm2, when measured at a pressure of 120 mmHg.
Device embodiments and components thereof may include metals, polymers, biologic materials and composites thereof. Suitable metals include zirconium-based alloys, cobalt-chrome alloys, nickel-titanium alloys, platinum, tantalum, stainless steel, titanium, gold, and tungsten. Potentially suitable polymers include but are not limited to acrylics, silk, silicones, polyvinyl alcohol, polypropylene, polyvinyl alcohol, polyesters (e.g. polyethylene terephthalate or PET), PolyEtherEther Ketone (PEEK), polytetrafluoroethylene (PTFE), polycarbonate urethane (PCU) and polyurethane (PU). Device embodiments may include a material that degrades or is absorbed or eroded by the body. A bioresorbable (e.g., breaks down and is absorbed by a cell, tissue, or other mechanism within the body) or bioabsorbable (similar to bioresorbable) material may be used. Alternatively, a bioerodable (e.g., erodes or degrades over time by contact with surrounding tissue fluids, through cellular activity or other physiological degradation mechanisms), biodegradable (e.g., degrades over time by enzymatic or hydrolytic action, or other mechanism in the body), or dissolvable material may be employed. Each of these terms is interpreted to be interchangeable. bioabsorbable polymer. Potentially suitable bioabsorbable materials include polylactic acid (PLA), poly(alpha-hydroxy acid) such as poly-L-lactide (PLLA), poly-D-lactide (PDLA), polyglycolide (PGA), polydioxanone, polycaprolactone, polygluconate, polylactic acid-polyethylene oxide copolymers, modified cellulose, collagen, poly(hydroxybutyrate), polyanhydride, polyphosphoester, poly(amino acids), or related copolymer materials. An absorbable composite fiber may be made by combining a reinforcement fiber made from a copolymer of about 18% glycolic acid and about 82% lactic acid with a matrix material consisting of a blend of the above copolymer with about 20% polycaprolactone (PCL).
Permeable shell embodiments 40, 340, 440 may be formed at least in part of wire, ribbon, or other filamentary elements 14, 314, 414. These filamentary elements 14 may have circular, elliptical, ovoid, square, rectangular, or triangular cross-sections. Permeable shell embodiments 40 may also be formed using conventional machining, laser cutting, electrical discharge machining (EDM) or photochemical machining (PCM). If made of a metal, it may be formed from either metallic tubes or sheet material.
Device embodiments 10, 310, 410 discussed herein may be delivered and deployed from a delivery and positioning system 112 that includes a microcatheter 61, such as the type of microcatheter 61 that is known in the art of neurovascular navigation and therapy. Device embodiments for treatment of a patient's vasculature 10, 310, 410 may be elastically collapsed and restrained by a tube or other radial restraint, such as an inner lumen 120 of a microcatheter 61, for delivery and deployment. The microcatheter 61 may generally be inserted through a small incision 152 accessing a peripheral blood vessel such as the femoral artery or brachial artery. The microcatheter 61 may be delivered or otherwise navigated to a desired treatment site 154 from a position outside the patient's body 156 over a guidewire 159 under fluoroscopy or by other suitable guiding methods. The guidewire 159 may be removed during such a procedure to allow insertion of the device 10, 310, 410 secured to a delivery apparatus 111 of the delivery system 112 through the inner lumen 120 of a microcatheter 61 in some cases.
Access to a variety of blood vessels of a patient may be established, including arteries such as the femoral artery 166, radial artery 164, and the like in order to achieve percutaneous access to a vascular defect 160. In general, the patient 158 may be prepared for surgery and the access artery is exposed via a small surgical incision 152 and access to the lumen is gained using the Seldinger technique where an introducing needle is used to place a wire over which a dilator or series of dilators dilates a vessel allowing an introducer sheath 162 to be inserted into the vessel. This would allow the device to be used percutaneously. With an introducer sheath 162 in place, a guiding catheter 168 is then used to provide a safe passageway from the entry site to a region near the target site 154 to be treated. For example, in treating a site in the human brain, a guiding catheter 168 would be chosen which would extend from the entry site 152 at the femoral artery up through the large arteries extending around the heart through the aortic arch, and downstream through one of the arteries extending from the upper side of the aorta such as the carotid artery 170. Typically, a guidewire 159 and neurovascular microcatheter 61 are then placed through the guiding catheter 168 and advanced through the patient's vasculature, until a distal end 151 of the microcatheter 61 is disposed adjacent or within the target vascular defect 160, such as an aneurysm. Exemplary guidewires 159 for neurovascular use include the Synchro2® made by Boston Scientific and the Glidewire Gold Neuro® made by MicroVention Terumo. Typical guidewire sizes may include 0.014 inches and 0.018 inches. Once the distal end 151 of the catheter 61 is positioned at the site, often by locating its distal end through the use of radiopaque marker material and fluoroscopy, the catheter is cleared. For example, if a guidewire 159 has been used to position the microcatheter 61, it is withdrawn from the catheter 61 and then the implant delivery apparatus 111 is advanced through the microcatheter 61.
Delivery and deployment of device embodiments 10, 310, 410 discussed herein may be carried out by first compressing the device 10, 310, 410 to a radially constrained and longitudinally flexible state as shown in
Once disposed within the vascular defect 160, the device 10, 310, 410 may then allowed to assume an expanded relaxed or partially relaxed state with the permeable shell 40, 340, 440 of the device spanning or partially spanning a portion of the vascular defect 160 or the entire vascular defect 160. The device 10, 310, 410 may also be activated by the application of an energy source to assume an expanded deployed configuration once ejected from the distal section of the microcatheter 61 for some embodiments. Once the device 10 is deployed at a desired treatment site 154, the microcatheter 61 may then be withdrawn.
Some embodiments of devices for the treatment of a patient's vasculature 10, 310, 410 discussed herein may be directed to the treatment of specific types of defects of a patient's vasculature. For example, referring to
Prior to delivery and deployment of a device for treatment of a patient's vasculature 10, 310, 410, it may be desirable for the treating physician to choose an appropriately sized device 10, 310, 410 to optimize the treatment results. Some embodiments of treatment may include estimating a volume of a vascular site or defect 160 to be treated and selecting a device 10, 310, 410 with a volume that is substantially the same volume or slightly over-sized relative to the volume of the vascular site or defect 160. The volume of the vascular defect 160 to be occluded may be determined using three-dimensional angiography or other similar imaging techniques along with software which calculates the volume of a selected region. The amount of over-sizing may be between about 2% and 15% of the measured volume. In some embodiments, such as a very irregular shaped aneurysm, it may be desirable to under-size the volume of the device 10, 310, 410. Small lobes or “daughter aneurysms” may be excluded from the volume, defining a truncated volume which may be only partially filled by the device without affecting the outcome. A device 10, 310, 410 deployed within such an irregularly shaped aneurysm 160 is shown in
In particular, for some treatment embodiments, it may be desirable to choose a device 10, 310, 410 that is properly oversized in a transverse dimension so as to achieve a desired conformance, radial force and fit after deployment of the device 10.
In
Once a properly sized device 10, 310, 410 has been selected, the delivery and deployment process may then proceed. It should also be noted also that the properties of the device embodiments 10, 310, 410 and delivery system embodiments 112 discussed herein generally allow for retraction of a device 10 after initial deployment into a defect 160, but before detachment of the device 10, 310, 410. Therefore, it may also be possible and desirable to withdraw or retrieve an initially deployed device 10 after the fit within the defect 160 has been evaluated in favor of a differently sized device 10, 310, 410. An example of a terminal aneurysm 160 is shown in
Detachment of the device 10, 310, 410 from the delivery apparatus 111 may be controlled by a control switch 188 disposed at a proximal end of the delivery system 112, which may also be coupled to an energy source 142, which severs the tether 72 that secures the proximal hub 68 of the device 10 to the delivery apparatus 111. While disposed within the microcatheter 61 or other suitable delivery system 112, as shown in
The device 10, 310, 410 may be inserted through the microcatheter 61 such that the catheter lumen 120 restrains radial expansion of the device 10, 310, 410 during delivery. Once the distal tip or deployment port of the delivery system 112 is positioned in a desirable location adjacent or within a vascular defect 160, the device 10, 310, 410 may be deployed out the distal end of the catheter 61 thus allowing the device to begin to radially expand as shown in
Upon full deployment, radial expansion of the device 10, 310, 410 may serve to secure the device 10, 310, 410 within the vascular defect 160 and also deploy the permeable shell 40 across at least a portion of an opening 190 (e.g. aneurysm neck) so as to at least partially isolate the vascular defect 160 from flow, pressure or both of the patient's vasculature adjacent the vascular defect 160 as shown in
For some embodiments, as discussed above, the device 10, 310, 410 may be manipulated by the user to position the device 10, 310, 410 within the vascular site or defect 160 during or after deployment but prior to detachment. For some embodiments, the device 10, 310, 410 may be rotated in order to achieve a desired position of the device 10 and, more specifically, a desired position of the permeable shell 40, 340, 440, prior to or during deployment of the device 10, 310, 410. For some embodiments, the device 10, 310, 410 may be rotated about a longitudinal axis of the delivery system 112 with or without the transmission or manifestation of torque being exhibited along a middle portion of a delivery catheter being used for the delivery. It may be desirable in some circumstances to determine whether acute occlusion of the vascular defect 160 has occurred prior to detachment of the device 10, 310, 410 from the delivery apparatus 111 of the delivery system 112. These delivery and deployment methods may be used for deployment within berry aneurysms, terminal aneurysms, or any other suitable vascular defect embodiments 160. Some method embodiments include deploying the device 10, 310, 410 at a confluence of three vessels of the patient's vasculature that form a bifurcation such that the permeable shell 40 of the device 10, 310, 410 substantially covers the neck of a terminal aneurysm. Once the physician is satisfied with the deployment, size and position of the device 10, 310, 410, the device 10, 310, 410 may then be detached by actuation of the control switch 188 by the methods described above and shown in
For some embodiments, a biologically active agent or a passive therapeutic agent may be released from a responsive material component of the device 10, 310, 410. The agent release may be affected by one or more of the body's environmental parameters or energy may be delivered (from an internal or external source) to the device 10, 310, 410. Hemostasis may occur within the vascular defect 160 as a result of the isolation of the vascular defect 160, ultimately leading to clotting and substantial occlusion of the vascular defect 160 by a combination of thrombotic material and the device 10, 310, 410. For some embodiments, thrombosis within the vascular defect 160 may be facilitated by agents released from the device 10 and/or drugs or other therapeutic agents delivered to the patient.
For some embodiments, once the device 10, 310, 410 has been deployed, the attachment of platelets to the permeable shell 40 may be inhibited and the formation of clot within an interior space of the vascular defect 160, device, or both promoted or otherwise facilitated with a suitable choice of thrombogenic coatings, anti-thrombogenic coatings or any other suitable coatings (not shown) which may be disposed on any portion of the device 10, 310, 410 for some embodiments, including an outer surface of the filaments 14 or the hubs 66 and 68. Such a coating or coatings may be applied to any suitable portion of the permeable shell 40. Energy forms may also be applied through the delivery apparatus 111 and/or a separate catheter to facilitate fixation and/or healing of the device 10, 310, 410 adjacent the vascular defect 160 for some embodiments. One or more embolic devices or embolic material 176 may also optionally be delivered into the vascular defect 160 adjacent permeable shell portion that spans the neck or opening 190 of the vascular defect 160 after the device 10 has been deployed. For some embodiments, a stent or stent-like support device 173 may be implanted or deployed in a parent vessel adjacent the defect 160 such that it spans across the vascular defect 160 prior to or after deployment of the vascular defect treatment device 10, 310, 410.
In any of the above embodiments, the device 10, 310, 410 may have sufficient radial compliance so as to be readily retrievable or retractable into a typical microcatheter 61. The proximal portion of the device 10, 310, 410, or the device as a whole for some embodiments, may be engineered or modified by the use of reduced diameter filaments, tapered filaments, or filaments oriented for radial flexure so that the device 10, 310, 410 is retractable into a tube that has an internal diameter that is less than about 0.7 mm, using a retraction force less than about 2.7 Newtons (0.6 lbf) force. The force for retrieving the device 10, 310, 410 into a microcatheter 61 may be between about 0.8 Newtons (0.18 lbf) and about 2.25 Newtons (0.5 lbf).
Engagement of the permeable shell 40, 340, 440 with tissue of an inner surface of a vascular defect 160, when in an expanded relaxed state, may be achieved by the exertion of an outward radial force against tissue of the inside surface of the cavity of the patient's vascular defect 160, as shown for example in
Although the foregoing invention has, for the purposes of clarity and understanding, been described in some detail by way of illustration and example, it will be obvious that certain changes and modifications may be practiced which will still fall within the scope of the appended claims.
This application is a continuation of U.S. application Ser. No. 16/815,911, filed Mar. 11, 2020, which claims the benefit of priority under 35 U.S.C. § 119(e) from U.S. Provisional Application Ser. No. 62/873,256, filed Jul. 12, 2019, all of which are hereby expressly incorporated by reference in their entireties for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62873256 | Jul 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16815911 | Mar 2020 | US |
| Child | 17572988 | US |
