Patent Application
20220218459
The present disclosure is directed generally to implantable blood filter devices and more specifically to filter devices to protect the brain and other organs from emboli.
Various conventional devices exist to contain or control the flow of thrombic material and atheroma debris. Examples of such devices include U.S. Pat. Nos. 6,712,834 and 6,866,680 to Yassour, et al., and U.S. Pat. No. 7,670,356 to Mazzocchi et al., which disclose blood filter devices designed to capture the debris material. A concern with capture filters is that they can foul to the extent that blockage of blood flow develops, with obvious consequences. Accordingly, these devices are typically unsuitable for long term or permanent implantation.
In another approach, U.S. Pat. No. 6,258,120 to McKenzie et al., U.S. Pat. No. 8,430,904 to Belson, U.S. Pat. No. 8,062,324 to Shimon et al., and U.S. Patent Application Publication No. 2009/0254172 to Grewe are directed to aortic diverters that divert emboli away from arteries. Diverter-type devices are limited to certain artery junction structures where flow diversion is a suitable substitute for filtering, and, in many instances, do not provide a positive barrier to emboli, either by design or because of the way they are mounted within the aorta. Furthermore, these devices can foul with debris build up over time, leaving no recourse for remedying the fouling, and so are not suitable for long term or permanent implantation. Also, diverter devices that are based on anchoring in the aorta require large diameter catheters for delivery. Other diverter-type devices include U.S. Pat. No. 8,460,335 to Carpenter, are held in place by the attendant deployment means, and thus suitable only for temporary service.
More recently, “self-cleaning” blood filters have been introduced, such as International Application No. WO 2015/173646 to Verin, et al., owned by the owner of the present application, and contents of which are hereby incorporated by reference herein in its entirety. Such self-cleaning blood filters can operate to provide a positive barrier that prevents emboli from entering the arteries from the aortic arch while enabling blood to flow through the structure, effectively keeping the structures clear of debris.
While the work of Verin et al. provides sound concepts for both temporary and permanent blood filters, putting these concepts into practice has raised special challenges. Self-cleaning blood filters that facilitate fabrication and deployment aspects would be welcomed.
Various embodiments of the disclosure disclose a blood filter having a support structure and a filter structure. These structures may have different porosities. For example, the support structure, which serves as an anchor for the blood filter may define a larger porosity, the larger pores of which promotes ample tissue growth therethrough that secures the device in place for permanent implant applications. The filter structure may define a smaller porosity, the smaller pores of which prevent emboli from passing therethrough. For fabrication and delivery purposes, the support and filter structures may be made separately and assembled. In some embodiments, the support structure presents a coarser mesh. In some embodiments, the support structure is an expanded metal structure, akin to a stent. In some embodiments, the filter structure presents a finer braided mesh that is overlaid on or otherwise attached to the support structure. In some embodiments, a polymer film is selectively applied to the filter structure and cooperates with the filter structure to provide a more uniform porosity over the filter structure.
Filtration of the blood includes deflection of emboli by the filter structure back into the aortic arch, as well as capture of emboli within the pores of the filter structure. In some embodiments, the filter structure is suspended away from the artery inlets. As such, the filter structure may be subject to cross flows during the cardiac cycle that may dislodge emboli from the filter structure, with the emboli being returned to the aortic arch and away from the inlets of the arteries. Accordingly, accumulation of emboli the filter structure is thereby reduced, such that the filter assembly is characterized as being “self-cleaning.”
Various embodiments of the filtering assemblies may be utilized as a temporary implant or a permanent implant. The elastic properties of the filtering assemblies enable minimally invasive delivery through blood vessels, and further enable collapsing the device for retrieval of temporary implantations.
Structurally, various embodiments of the disclosure disclose a filter assembly for filtering blood entering an artery from an aortic arch, comprising a filter structure and a support structure that cooperate to define an anchor leg and a filter leg. The anchor leg defines a distal opening and extends along a first central axis. The first central axis extends in an inferior direction from the distal opening toward an elbow portion of the filter leg, the filter leg being proximal to the anchor leg and defining and extending along a second central axis. The filter leg includes the elbow portion and an extension portion, the elbow portion extending from the anchor leg and separating the anchor leg from the extension portion. The support structure extends from the elbow portion into the extension portion.
In some embodiments, the filter structure is configured to slide on the support structure. The support structure may include at least one rail that extends into the extension portion, the filter structure being slidable on the rail. In some embodiments, the at least one rail may form a loop proximal to the filter structure. The loop may be configured as a snare portion for retrievability of the filter assembly, and may include a crimp attached to a proximal end of the loop, which may include a radiopaque material.
In some embodiments, the filter assembly defines an assembled length that extends from the first central axis at a distal opening of the anchor leg to an inside surface of the loop at the second central axis when the filter assembly is in a pre-implant configuration. The loop defines an inside length along the second central axis that extends from a proximal end of the filter structure to the inside surface of the loop when the filter assembly is in a pre-implant configuration. In some embodiments, a ratio of the assembled length to the inside length is in a range of 5 to 1 inclusive.
In some embodiments of the disclosure, the anchor leg includes a tail portion that extends distally beyond the assembled length, the tail portion being configured as a snare portion for retrievability of the filter assembly. The snare portion may include a hook structure. The tail portion may include a crimp attached to a distal end of the tail portion, the crimp including a radiopaque material.
In some embodiments of the disclosure, the filter structure and the support structure are interlaced. The filter structure may be one of a braided structure and a woven structure. In some embodiments, the filter structure and the support structure are tightly interlaced at the elbow portion to secure the filter structure to the support structure, while the filter structure and the support structure are loosely interlaced at the extension portion to enable the filter structure to slide over the support structure.
In some embodiments, the filter structure may include opposed lateral edges that are lateral to the second central axis, each of the opposed lateral edges including a hem structure that enables the filter structure to slide over the support structure. The extension portion of the filter structure defines an arcuate cross-section orthogonal to the second central axis that partially surrounds the second central axis, the arcuate cross section extending away from the central axis in the inferior direction. The arcuate cross-section may define one of a U-shape and a V-shape.
In some embodiments, a distal end of the filter structure is fastened to the anchor leg.
In some embodiments, a distal end of the filter structure defines closed neck. The distal end of the filter structure may be fastened to the anchor leg with crimps, and the crimps may include a radiopaque material suitable for visualization with an imaging system. In some embodiments, the closed neck wraps around anchor leg. In other embodiments, the distal end of the filter structure abuts against the anchor leg to define a diameter that is substantially the same as a diameter of the anchor leg. In some embodiments, the anchor support structure defines a first area porosity that is within a range of 60% to 98% inclusive. A mesh used to fabricate the filter structure may define a second area porosity that is within a range of 50% to 98% inclusive. A nominal pore size of the support structure may be greater than a nominal pore size of the filter leg. In some embodiments, the nominal pore size of the support structure is within a range of 0.5 to 8 millimeters inclusive; in some embodiments, within a range of 0.5 to 5 millimeters inclusive; in some embodiments, within a range of 0.5 to 3 millimeters inclusive. In some embodiments, the nominal pore size of the filter mesh of filter structure is within a range of 0.2 to 0.8 millimeter inclusive. In some embodiments, a ratio of the nominal pore size of the support structure to the nominal size of the filter mesh of filter structure is within a range of 2.5 to 55 inclusive; in some embodiments, within a range of 2.5 to 40 inclusive; in some embodiments, within a range of 2.5 to 25 inclusive.
When the filter assembly is in an implant configuration, a lateral projection of the first central axis and the second lateral axis may define a minimum projected angle, the minimum projected angle being within a range of 40 degrees to 80 degrees inclusive. In some embodiments, the minimum projected angle is within a range of 50 degrees to 70 degrees inclusive.
In various embodiments of the disclosure, a filter assembly for filtering blood entering an artery from an aortic arch is disclosed, comprising an anchor leg and a filter leg that extends from the anchor leg, the filter leg including an elbow portion, the anchor leg defining a first central axis that extends in a first direction from the anchor leg away from the elbow portion, and a support structure extending from the anchor leg along the filter leg, the support structure including a pair of support rails that extend beyond the elbow portion along the filter leg. A first support rail of the pair of support rails may define a first shape beyond the elbow portion, and a second support rail of the pair of support rails may define a second shape beyond the elbow portion. In some embodiments, the second shape extends further in the first direction than the first shape.
The first shape and the second shape may each arc toward a second direction, the second direction being opposite the first direction. The first shape and the second shape may each arc toward a first lateral direction, the first lateral direction being perpendicular to the first direction. In some embodiments, the anchor leg is configured to anchor the filter assembly in a brachiocephalic artery. The first shape and the second shape may each configured for continuous contact along a roof of an aortic arch, the continuous contact of the first shape being anterior to the continuous contact of the second shape In some embodiments, a filter structure is coupled to the pair of rails, the filter structure including a web portion that extends between the pair of rails. The filter structure may define an arcuate cross-section orthogonal to the second central axis, the arcuate cross section extending in a second direction that is opposite the first direction. In some embodiments, the cross-section defines one of a U-shape and a V-shape.
In various embodiments of the disclosure, filter assembly for filtering blood entering an artery from an aortic arch is disclosed, comprising a filter structure and a support structure that cooperate to define an anchor leg and a filter leg, the anchor leg defining a distal opening and extending along a first central axis, the first central axis extending in an inferior direction from the distal opening toward an elbow portion of the filter leg, the filter leg being proximal to the anchor leg and defining and extending along a second central axis, the filter leg including the elbow portion and an extension portion, the elbow portion extending from the anchor leg and separating the anchor leg from the extension portion, A perforated polymer coating may cover an outer contour of the elbow portion, and defines a plurality of perforations that pass through the perforated polymer coating. In some embodiments, the perforations of the plurality are sized within a range of 0.2 to 0.8 millimeter diameter inclusive. In some embodiments, the perforated polymer coating defines an area porosity that is within a range of 60% to 98% inclusive.
In various embodiments of the disclosure, a method of making this filter assembly comprises: coating the outer contour of the elbow portion with a polymer; and forming the plurality of perforations through the polymer. The polymer may be applied as a liquid and allowed to harden before the step of forming. The plurality of perforations may be formed by a laser cutting process. In some embodiments, the filter assembly is formed to shape over a mandrel and heat set to form the elbow portion prior to the step of coating.
In various embodiments of the disclosure, a method of collapsing a filter assembly for vascular delivery is disclosed, comprising: bending a filter assembly from an implant configuration to a pre-implant configuration; collapsing the filter assembly toward a central axis of the pre-implant configuration; and sliding at least a portion of a filter structure of the filter assembly along a support structure of the filter assembly during the step of collapsing to elongate the filter structure along the central axis of the pre-implant configuration. The filter structure may slide along a rail of the support structure during the step of sliding. The filter structure may include a hem that slides along the rail of the support structure during the step of sliding. The
filter assembly in the steps of bending and collapsing may be made of super-elastic material, such as a nickel titanium alloy and a cobalt-chromium-nickel-molybdenum-iron alloy.
In various embodiments of the disclosure, a method of forming rails on a support structure of a filter assembly is disclosed, comprising: forming a plurality of pre-expansion pores at a first end portion of a tube to define a pre-expansion anchor portion; cutting at least one segment proximal to the pre-expansion anchor portion to form at least one rail extending proximal to the pre-expansion anchor portion; and expanding the tube to define an expanded anchor portion. In some embodiments, a ratio of a length that the rail extends from the expanded anchor portion to a length of the expanded anchor portion is in range of 0.2 to 1.5 inclusive. A taper may be formed at a distal end of the pre-expansion anchor portion. In some embodiments, the method includes coupling a filter structure to the at least one rail portion, the filter structure including a proximal end, and closing the at least one rail portion to form a loop with the proximal end of the filter portion to support the filter structure. During the step of coupling, the filter structure may include capturing the at least one rail portion within a hem structure of the filter structure. In some embodiments, the at least one rail portion in the step of cutting at least one segment is two rail portions, wherein the step of closing may include joining proximal ends of the two rail portions together. The tube in the step of forming the plurality of pre-expansion pores may be a circular tube. In some embodiments, the steps of cutting are performed with a laser.
In various embodiments of the disclosure, a method of forming a filter assembly for a blood filter is disclosed, comprising: forming a tubular sleeve structure defining a substantially linear central axis, the tubular sleeve structure defining a wall porosity; partially severing the tubular sleeve structure to form severed edges that are bridged by a hinge portion, the hinge portion extending along one side of the tubular sleeve structure; rolling or folding the severed edges back along an inside of the tubular sleeve structure to define opposed mitered edges, the opposed mitered edges defining a miter angle when the tubular sleeve defines the substantially linear central axis; and closing the miter angle about the hinge portion to define an elbow shape. In some embodiments, the tubular sleeve is mounted on a mandrel to close the miter angle, and may be heat setting the tubular sleeve on the mandrel. The method may include the step of sliding the sleeve structure over a support structure to close the miter angle.
In various embodiments of the disclosure, a filter assembly for filtering blood flowing into an artery is disclosed, comprising a tubular support structure that defines a first open end and a second open end that is opposed to the first open end, the tubular support structure having a tubular wall that defines a wall area porosity, the tubular support structure being curved to define a first leg portion and a second leg portion, the second leg portion including an elbow portion that extends from the first leg portion, the first leg portion defining the first open end and a first central axis, the second leg portion defining the second open end and a second central axis, the first central axis and the second central axis defining a minimum projected angle of the first central axis and the second central axis that is less than 180 degrees. A filter structure may define a filter area porosity and may be coupled to the second leg portion of the tubular support structure, In some embodiments, the filter assembly defines an inside portion that faces inward and an opposed outside portion that faces outward. The filter structure and the tubular support structure may define a combined area porosity that is less than the wall area porosity. In some embodiments, the filter structure is arranged so that at least part of the outside portion of the filter assembly defines the combined area porosity at the elbow portion and the second leg portion, and at least part of the inside portion defines the wall area porosity at the second leg portion. In some embodiments, the minimum projected angle is an obtuse angle; in others, the minimum projected angle is an acute angle. In some embodiments, the minimum projected angle is in a range of 40 degrees to 80 degrees inclusive; in some embodiments, the minimum projected angle is in a range of 50 degrees to 70 degrees inclusive.
In some embodiments, the filter structure is disposed on an interior of the tubular support structure; in others, the filter structure is disposed on an exterior of the tubular support structure. The filter structure may be attached to the tubular support structure with at least one of a threaded wire, a plurality of stitches, and a plurality of point-wise tack welds. In some embodiments, the tubular support structure includes one of a braided structure and a woven structure, the tubular support structure including a plurality of pores defined therethrough.
The tubular support structure may be of a coarse wire mesh, wherein the coarse wire mesh includes wire having a diameter in a range of 100 micrometers to 300 micrometers inclusive and defining pore sizes in a range of three millimeters to five millimeters inclusive, the coarse wire mesh being one of a braided structure and a woven structure. The coarse wire mesh may be formed from a single continuous wire. In some embodiments, wire is composed of a material that includes one of a cobalt-chromium-nickel-molybdenum-iron alloy and a nickel-titanium alloy. The material may be one of NITINOL and an alloy specified by ASTM F 1058 or ISO 5832-7.
In some embodiments, the filter structure is a two-dimensional structure that conforms to a shape of the tubular support structure when coupled to the tubular support structure. The filter structure may be one of a braided structure and a woven structure that is integrated with the elbow portion and the second leg portion. In some embodiments, the filter structure is a fine wire mesh, wherein the fine wire mesh is braided or woven with wire having a diameter in a range of 30 micrometers to 100 micrometers inclusive. The fine wire mesh may define a plurality of non-circular pores, each having a nominal major dimension in a range of 200 micrometers to 800 micrometers inclusive and may be woven or braided from a single wire.
In some embodiments, the wire is of a super elastic material, such as NITINOL.
In various embodiments of the disclosure, a method of manufacturing a filter assembly is disclosed, comprising: forming the tubular support structure about a substantially linear axis; fitting the tubular support structure over a curved mandrel to define the minimum projected angle; heat treating the tubular support structure on the mandrel; and coupling the filter structure to the elbow portion and the leg portion. The filter structure may be a tubular sleeve structure defining a plurality of apertures formed on a first side thereof, the plurality of apertures being arranged so that the inside portion of the filter assembly defines the wall area porosity of the tubular support structure through the plurality of apertures. In some embodiments, one or more of the plurality of apertures is arranged on the first side for substantial alignment with ostia of arteries that branch from an aortic arch when the filter assembly is implanted in the aortic arch.
In various embodiments of the disclosure, a method of manufacturing a filter assembly, includes: forming the tubular sleeve structure of the filter structure about a substantially linear axis; fitting the tubular sleeve structure over a mandrel, the mandrel including a plurality of apertures on one side that pass through a wall of the mandrel into a hollow defined by the mandrel; heat treating the tubular support structure on the mandrel; forming a plurality apertures in the tubular sleeve structure that pass through the plurality of apertures of the mandrel; and coupling the filter structure to the elbow portion and the leg portion of the tubular support structure. The step of coupling the filter structure to the elbow portion and the second leg portion of the tubular support structure may include arranging the filter structure on an exterior of the tubular support structure, and the step of forming the tubular support structure may include one of a weaving or a braiding process.
In various embodiments of the disclosure, a filter assembly is disclosed, comprising a tubular support structure that defines a first open end and a second open end that is opposed to the first open end, the tubular support structure having a tubular wall that defines a wall area porosity, the tubular support structure being curved to define a first leg portion and a second leg portion separated by an elbow portion, the first leg portion defining the first open end and a first central axis, the second leg portion defining the second open end and a second central axis, the first central axis and the second central axis intersecting to define an apex angle that is less than 180 degrees, the apex angle defining a central plane of the tubular support structure. A filter structure may define a filter area porosity and being coupled to the elbow portion and the second leg portion of the tubular support structure. In some embodiments: the filter assembly defines an inside portion that faces toward the apex angle and an opposed outside portion that faces away from the apex angle; the filter structure and the tubular support structure define a combined area porosity that is less than the wall area porosity; and the filter structure is arranged so that at least part of the outside portion of the filter assembly defines the combined area porosity at the elbow portion and the second leg portion, and at least part of the inside portion defines the wall area porosity at the second leg portion.
Referring to
Referring to
The anchor leg portion 46 defines a first opening 36, the first central axis 47 being concentric with a center of the first opening 36. The filter leg portion 48 defines a superior side 61 and an inferior side 63 of the filter assembly 30. The first central axis 47 and the second central axis 49 project a minimum projected angle θ onto a lateral projection plane 66, the minimum projected angle θ being defined about the lateral axis 54 and being less than 180 degrees.
For filter leg portions 48 having components with cross-sections normal to and surrounding the second central axis 49 along the extension portion 53, the second central axis 49 is defined as concentric with the filter leg portion 48. Examples of such components include the support structures 32a and 32b of
The elbow portion 52 constitutes a segment of the filter assembly 30 that is bounded distally by boundary plane 62 and proximally by boundary plane 64. Boundary plane 62 is normal to the first central axis 47 and intersects the first central axis 47 where the filter assembly 30 exits the ostium of the anchoring artery when properly implanted. Boundary plane 64 intersects the second central axis 49, is orthogonal to the lateral projection plane 66, and is tangent to an edge of the anchor leg portion 46. The depiction of
In some embodiments, the anchor leg portion 46 of the filter assembly 30 is dimensioned for anchoring within an innominate (brachiocephalic) artery. The filter leg portion 48 may extend proximally to a length long enough to cover the ostium of the left common carotid artery when implanted in an innominate artery of the aortic arch 31 of the heart. In some embodiments, the filter leg portion 48 is long enough to cover the ostia of both the left common carotid artery and the left subclavian artery when implanted in the innominate artery.
Functionally, the support structure 32 supports the filter structure 34 in a preferred orientation that filters blood entering one, some, or all of the inlets of the innominate artery, the left common carotid artery, and the left subclavian arteries at the aortic arch. During implantation, the anchor leg portion 46 of the support structure 32 is implanted within an anchoring artery (e.g., the brachiocephalic artery). The filter leg portion 48 may be oriented to extend over the inlets of arteries proximate the anchoring artery (e.g., the left common carotid artery and the left subclavian arteries). The anchor leg portion 46 is inserted into the anchoring artery 26, contacting the walls of the anchoring artery 26 and bringing the filter leg portion 48 into contact with a superior surface of the aortic arch 31.
This disclosure presents several embodiments of filter assemblies 30, all of which have in common the support structure 32 and the filter structure 34, albeit in configurations that differ from those presented in
For the filter assembly 30a, the support structure 32a includes a tubular wall 42 that defines an area porosity 44. The filter assembly 30a also defines a second opening 38. For the filter assembly 30a, the second opening 38 is defined by the filter leg portion 48, and both of the openings 36 and 38 are be defined by the support structure 34a. In some embodiments, the second opening 38 is defined by the anchor leg portion 46 (
The filter assembly 30a defines an inside portion 102 that faces inward and an opposed outside portion 104 that faces outward. The filter structure 34a and the support structure 32a define a combined area porosity 106 that is less than the area porosity 44 of the support structure 32a. In some embodiments, the filter structure 34a is arranged so that at least part of the outside portion 104 of the filter assembly 30a defines the combined area porosity 106 at the filter leg portion 48, and at least part of the inside portion 102 defines the area porosity 44 at the filter leg portion 48. Herein, an “area porosity” is defined by a ratio of the normal projected area of the voids of a porous material to the total normal area of the porous material.
In some embodiments, the mesh 84 from which the filter structure 34 is fabricated defines a porosity in the range of 50% to 98% inclusive; in some embodiments, in a range from 60% and 95% inclusive; in some embodiments, in a range from 70% and 95% inclusive; in some embodiments, in a range from 75% and 90% inclusive. In some embodiments, the support structure defines a porosity in the range of 60% to 98% inclusive; in some embodiments, in a range from 70% and 95% inclusive; in some embodiments, in a range from 75% and 95% inclusive; in some embodiments, in a range from 80% and 95% inclusive.
In some embodiments, a coarse wire mesh 82 is exposed on the inside portion 102 of the filter assembly 30a that contacts the superior surface of the aortic arch surrounding the inlets of the arteries. The pores of the coarse wire mesh 82, being larger than the pores of the filter structure 34, enables filtered blood to flow into artery inlets without further obstruction.
For permanent implants, the larger pores 76 of the coarse wire mesh 82 of the support structure 32 also facilitates securing the filter assembly 30. Typically, after about 4 weeks' time, tissue on the anchoring artery grow into the larger pores 76 of the coarse wire mesh 82 of the anchor leg portion 46, and also enables the contacted tissue on the aortic arch to grow into the pores of the filter leg portion 48. The growth of the tissue into the larger pores 76 of the support structure 32 secures the filter assembly 30 in the preferred orientation.
In some embodiments, the filter structure 34a is fabricated from an expanded sheet 70 (e.g., expanded metal;
In some embodiments, a method of manufacturing the filter assembly 30a includes weaving or braiding the support structure 32a about a substantially linear axis. Herein, “weaving” is a process that creates fixed cross-over points between crossing wires or filaments, whereas “braiding” is a process where the crossing wires or filaments are not fixed (i.e., crossing wires or filaments can slide with respect to each other). The support structure 32a is fitted over a curved mandrel (not depicted) to define the projected angle θ, and may be heat set on the mandrel to thermally set the curved shape of the support structure 32a. The filter structure 34a is then coupled to the filter leg portion 48 of the support structure 32a. The filter structure 34a may be attached to the support structure 32a with a threaded wire, a plurality of stitches, a plurality of point-wise tack welds, or a combination of such techniques. In some embodiments, the filter structure 34a is braided directly onto the filter leg filter leg portion 48 of the support structure 32a.
Referring to
In some embodiments, the coarse mesh 82 is braided or woven with wire having a diameter in a range of 100 micrometers to 300 micrometers inclusive, with nominal pore sizes in a range of 0.5 millimeters to five millimeters inclusive. In some embodiments, the nominal pore sizes are in a range of two millimeters to seven millimeters inclusive. (Herein, a range that is said to be “inclusive” includes the endpoint values of the range as well as all values therebetween.) In some embodiments, a ratio of the nominal pore size of the support structure 32 to the nominal size of the filter mesh 84 of filter structure 34 is within a range of 2.5 to 55 inclusive; in some embodiments, the ratio is within a range of 2.5 to 40 inclusive; in some embodiments, the ratio is within a range of 2.5 to 25. In some embodiments, the coarse mesh 82 is a woven mesh and may be braided from a single wire. Likewise, in some embodiments, the fine mesh 84 is a woven mesh that may be braided from a single wire.
Herein, a “pore” is a void bounded by a structural component or components, for example the wires of a woven mesh (e.g., pores 76 of meshes 82 and 84 of
“Pore size” is defined as the diameter of a largest circle 110 that will fit within the inner dimensions of the pore 76. An illustration is depicted at
Examples of suitable metallic materials for the various filter assemblies 30 include so-called “super elastic” alloys such as certain nickel-titanium alloys (e.g., NITINOL), which allows up to 8% elastic deformation. Other examples of sufficiently elastic alloys include cobalt-chromium-nickel-molybdenum-iron (CoCrNi) alloys specified by ASTM F 1058 and ISO 5832-7, such as ELGILOY®, PHYNOX®, CONICHROME®, and FWM® 1058. Such CoCrNi alloys, though not “super elastic”, possesses sufficient elasticity by virtue of a high yield stress.
Referring to
Herein, an “aperture” is a hole formed through a material, for example by cutting, punching, flaring, or by braiding about a mandrel. Accordingly, the apertures 114 are distinguishable from the pores 76 of the meshes 82 or 84. That is, when formed on the mesh 82 or 84, an aperture 114 refers to a through-hole defined by or through the mesh 82, 84 that is larger than the pores of the mesh 82, 84.
Referring to
In some embodiments, the plurality of apertures 114 of the tubular sleeve structure 112 are formed using the plurality of apertures 132 of the mandrel 130 as a guide, for example by passing a punch or a flare tool through the tubular sleeve structure 112 and into the apertures 132 of the mandrel 130. In some embodiments, excess mesh material from the formation of the apertures 132 is rolled or folded back into the tubular sleeve structure 112 to form rims 138 about the apertures 132. In some embodiments, the apertures 132 define an aperture diameter 140 that is within a range of three millimeters to eight millimeters inclusive.
The filter structure 34 is then coupled to the support structure 32, for example the support structures 32a or 32b. Other support structures 32 disclosed throughout this disclosure may also be utilized. In some embodiments, the step of coupling the filter structure 34 to the support structure 32 includes arranging the filter structure 34c on the exterior 72 (
Functionally, the plurality of apertures 114 can facilitate tissue growth into the filter leg portion 48, which is desirable for permanent implants. Those apertures 114 which align with the ostia prevent reduction of blood flow into the arteries that would otherwise be caused by the presence of the mesh 35 over the ostia.
Referring to
An artifact of some filter assemblies 30 when in the implanted configuration 22 is a distortion of the sizes of the pores 76 at the elbow portion 52. Particularly, filter structures 34 that are arcuate about the second central axis 49 and define the outer contour 58 as arcuate about the lateral axis 54 are stretched or put in tension about the outer contour 58 of the elbow portion 52. The stretching causes the pores 76 on the outer contour 58 to increase in size, in some cases by as much as 70% or more. Accordingly, the porosity of the filter structure 34d sans the perforated polymer overcoat 162 is increased in the vicinity of the outer contour 58. The increased sizes of the pores 76 may diminish the filtering capability of the filter assembly 30. The elbow portion 52, being disposed upstream in the blood flow when deployed, is a particularly active filtering region of the filter assembly 30. In some embodiments, the perforated polymer overcoat 162 is loaded with or coated with an anti-thrombic compound.
Functionally, the perforations 166 enable the porosity of the filter structure 34d to be controlled so that the porosity in the region of the outer contour 58 is in substantial uniformity with the remainder of the filter structure 34d. In some embodiments, the perforations of the plurality of perforations are sized within a range of 0.2 to 0.8 millimeter diameter inclusive. Furthermore, the perforated polymer overcoat 162 may be of suitable flexibility to enable the filter assembly 30 to be straightened and collapsed for delivery. The tail structure 168 provides a snag for purposes of retrieving the filter assembly 30. The crimp 170, particularly when made of a radiopaque material, provides a location marker of the tail structure 168 for various imaging systems (e.g., x-rays). Loading the perforated polymer overcoat 162 polymer with the anti-thrombic compound can cause the overcoat 162 to elute the anti-thrombic compound over time, thereby reducing fibrin formation and preventing clots from forming and growing or otherwise preventing platelets from clumping and preventing clots from forming and growing on the perforated polymer overcoat 162.
In fabrication, the tubular sleeve 112 the filter structure 34c may be braided about a substantially linear axis (
The perforations 166 may be formed, for example, using a laser cutting process or a mechanical puncturing process. Various perforation techniques can be adapted to form the perforations 166 while not substantially compromising the structural integrity of the mesh 84. For example, laser cutting may utilize a laser intensity that is suitable for cutting the polymer coating 174 but that does not damage a mesh 84 that is metallic. In another example, a mechanical puncturing process may incorporate needles that come to a sharp point that deflects either the (metallic) mesh 84 or the needle punch upon incidence with the mesh 84.
The technique of applying the perforated polymer overcoat 162 is not limited to filter structures 34. Certain embodiments include support structures 32 that may perform a filtering function (e.g., the support structure 32f of
While the embodiment of
Referring to
In the pre-implant configuration 164, the filter structure 34e is characterized by a partial discontinuity 186 at the elbow portion 52 that forms mitered edges 188. The mitered edges 188 define a miter angle ϕ when the tubular sleeve structure 112 is substantially concentric with a linear axis 192. A hinge portion 194 bridges one side of the discontinuity 186. In the implanted configuration 22, the discontinuity 186 is closed to form a miter 196, with the hinge portion 194 aligned along the outer contour 58 of the implanted configuration 22. The miter angle ϕ may be sized so that a resulting angle α about the miter 196 of the implanted configuration 22 is congruent with the desired minimum projected angle θ. In some embodiments, the form of the implanted configuration 22 of the filter structure 34e is maintained by the support structure 32, for example support structures 32a or 32b. Other support structures 32 disclosed throughout this disclosure may also be utilized with the filter structure 34e.
Fabrication of the filter structure 34e may include braiding or weaving the tubular sleeve structure 112 of the filter structure 34e about a substantially linear axis and partially severing the tubular sleeve structure 112, leaving the hinge portion 194 in place. Folds or rolls 198 may be formed at the edges of the partial sever by folding or rolling the severed edges back along the inside of the tubular sleeve structure 112 to define the mitered edges 188. The degree to which the severed edges are folded or rolled back defines the miter angle ϕ of the filter structure 34e when in the implanted configuration 22. The filter structure 34e may be formed to the shape of the implanted configuration 22 using a mandrel (not depicted) and heat setting the shape.
Functionally, the pores 76 of the filter structure 34e experience less distortion in the implanted configuration 22 than do the pores 76 of certain filter structures 32, such as filter structure 32d. As a result, in some embodiments, the porosity along the outer contour 58 of the filter structure 34e in the implanted configuration 22 is not substantially increased, and may not require remedial attention, such as the perforated polymer overcoat 162 (
Referring to
The filter structure 34f extends from a distal end 232 to a proximal end 234, defining an assembled length 236. The filter structure 34f may define a channel-shaped portion 238 at the proximal end 234 and transition to a closed neck portion 244 at the distal end 232 that defines the first opening 36 of the filter assembly 30f. In some embodiments, the first opening 36 is bounded by a hoop structure 242 that is integral with the filter structure 34f. The rails 222 may extend to the hoop structure 242. The channel-shaped portion 238 may define a cross-section 246 in a plane that is orthogonal to the second central axis 49. The cross-section may define, for example, a U-shape (depicted) or a V-shape. The channel-shaped portion 238 includes opposed lateral edge portions 248 separated by a web portion 252. The filter structure 34f is coupled to the rails 222 at the opposed lateral edge portions 248 and at the closed neck portion 244.
The rails 222 extend at beyond the proximal end 234 of the filter structure 34f to define an inside length 254 of the loop 228. The inside length 254 is defined as the distance along the second central axis 49 from the proximal end 234 of the filter structure 34, 34f to an intersection of an inside surface of the loop 228 with the second central axis 49 when the filter assembly 30, 30f is in a pre-implant configuration (
In fabrication, the filter structure 34f may be interlaced with the rails during formation of the mesh 84 of the filter structure 34f In this way, the rails 222 are incorporated into mesh 84. The distal end portions 226 of the rails 222 may be woven into the mesh 84. In this way, the filter structure 34f captures the rails 222. The rails 222, being substantially stouter than the filter structure 34f, provide support for the filter structure 34f.
The distal end portions 226 of the rails 222 may be tightly woven into the mesh 84 at or proximate the closed neck portion 244. In contrast, the rails 222 may be loosely woven into the mesh 84 within the channel-shaped portion 238. Other forms of attaching the rails to the mesh 84 may also be implemented, for example tac welding. In some embodiments, the hoop structure 242 is formed by rolling or folding excess material of the mesh 84 at the first opening 36.
The rails 222 are coupled together at the proximal end portions 224 and formed to shape the loop 228. The loop 228 defines the inside length 254 beyond the proximal end 234 of the filter structure 34f when in the pre-implant configuration 164. The proximal end portions 224 of the rails 222 may be coupled, for example, with a crimp 258, which may comprise a radiopaque material. Other techniques for coupling the proximal end portions 224 of the rails 222 include, for example, twisting together, fusion, and tac welding. The filter assembly 30f is formed to shape (e.g., with mandrel) and heat set.
Functionally, the tight weave of the mesh 84 about the distal end portions 226 of the rails 222 may secure the rails 222 to the filter structure 34f. Conversely, the loose weave of the mesh 84 about the rails 222 within the channel-shaped portion 238 enables a sliding action between the rails 222 and the channel-shaped portion 238. The sliding fit of the loose weave in combination with the inside length 254 facilitates collapsing the filter assembly 30f for deployment. Herein, to “collapse” the filter assembly 30 refers to substantially straightening the filter assembly 30 about a linear axis and constricting the filter assembly 30 to within a reduced diameter (typically about two millimeters) for insertion into a delivery device.
When the mesh 84 is collapsed, the pores 76 are elongated, causing the major dimension 86 (
The hoop structure 242 may enhance separation of the rails 222 from each other when transitioning between a collapsed configuration to the implanted configuration 22. The hoop structure 242 may also provide some biasing of the first opening 36 against the wall of the host artery. The loop 228 assures capture of the filter structure 34f within the support structure 32f. The radiopaque crimp 258, when utilized, serves as a location marker for various imaging systems. The crimp 258 can also function as a snare to facilitate retrieval of the filter assembly 30f. The larger cross section of the rails 222 relative to the strands of the mesh 84 enable the rails 222 to support and shape the filter structure 34f, causing the filter structure 34f to conform to the heat set shape of the rails 222. The cross sections of the rails 222 also provide spring biasing of the filter leg portion 48 for seating against the roof of the aortic arch 31.
In some embodiments, the rails 222 are made of wire. The wire is of substantially heavier gauge than that of the mesh 84. In some embodiments, the diameter of the wire forming the rails 222 is in a range of 100 to 500 micrometers inclusive; in some embodiments, in a range of 100 to 350 micrometers inclusive. In some embodiments, the cross-sections of the rails 222 may range from 0.03 to 0.4 square millimeters inclusive.
Referring to
A planar projection 306 of a pre-expanded tube structure 308 prior to expansion is depicted at
The filter structure 34g, depicted at
In fabrication, the pre-expansion pores 314 and hook portion 324 are formed in the pre-expanded tube structure 308, for example in a laser cutting process. The pre-expanded tube structure 308 may also be trimmed to define the taper at the distal edge 320. In some embodiments, elongate segments 309 (depicted in phantom in
For the filter structure 34g, the hem structures 338 may be formed by folding and fastening lateral extremities 344 of the mesh 84 to the web portion 252 to define the lateral edge portions 248. Fastening of lateral extremities 344 to the web portion 252 may be accomplished, for example, with an interwoven wire 340. The hem structures 338 are slid over the open rails 222 and brought into contact with the anchor portion 302. In some embodiments, the distal end 336 of the channel structure 332 is attached to the anchor portion 302, for example, with wire sutures or crimps 346. The crimps 346 may include a radiopaque material. The distal end 336 of the filter structure 34g may be disposed inside the second opening 38 the anchor portion 302, wrapped around the second opening 38 of anchor portion 304, or brought into abutment or otherwise align with the second opening 38 of the anchor portion 304. In the abutment option, the distal end 336 of the filter structure 34g defines a radius that is substantially the same as the radius of the anchor leg 46 about the first central axis 47, thereby reducing the effect of any axial discontinuity at the second opening 38.
The proximal end portions 224 of the rails 222 are formed to shape the loop 228 and define the inside length 254 beyond the proximal end 234 of the filter structure 34g. As with the filter assembly 30f, the proximal end portions 224 of the rails 222 may be coupled with a radiopaque crimp 258 (depicted), or by other techniques available to the artisan. The filter assembly 30g is formed to shape (e.g., with mandrel) and heat set.
In some embodiments, the filter structure 34g is fabricated from a polymer material. The pores 76 of the mesh 84 may be formed, for example, by laser cutting and/or expansion techniques. The hem structures 338 may be fabricated by fusing the lateral extremities 344 of the mesh 84 to the web portion 252.
Functionally, the hem structures 338 facilitate sliding of the filter structure 34g along the rails during the axial elongation that occurs when collapsing the filter assembly 30g for deployment. The hem structures 338 also facilitate assembly of the filter assembly 30g without interlacing the mesh 84 onto the support structure 32, and also enable use of different materials (e.g., polymer) for the filter structure 34g. As with the filter assembly 30f, the sliding action accommodates repositioning of the channel-shaped portion 238 relative to the rails 222 when transitioning between the pre-implant configuration 164 and the implanted configuration 22.
When implanted in the aortic arch 31, filter structures 34 that have a channel-shaped portion 238 (e.g., filter structures 34a, 34f, and 34g) suspend the mesh 84 of the web portion 252 away from the roof of the aortic arch 31 and the ostia of the arteries, which reduces the effect of pore blockage. Consider a configuration where the mesh structure is in apposition with the aortic roof at the perimeter of the ostia. Essentially, all of the blood flowing into the respective artery must pass through those pores which are bounded by the perimeter of the respective ostium. If some of the pores become blocked, the flow area into the artery is partially obstructed. Should such blockage become significant, blood flow into the artery may be substantially compromised.
By suspending the mesh 84 away from the ostia, the blood flow into a given artery is spread over a larger area of the filter structure 34. Spreading the blood flow over a larger area (i.e., over more pores of the filter structure 34) mitigates the effect of pore blockage. That is, if emboli entrained in the blood flow blocks a pore 76 of filter structure 34, the blockage affects a smaller fraction of the total number of pores 76 through which blood flows. Also, should several pores 76 become blocked such that the blockage of pores becomes significant, the blood flow will flow around the significant blockage by utilizing more pores adjacent to the blockage. The suspension of web portion 252 away from the roof of the aortic arch 31 also facilitates the self-cleaning aspect of the filter assembly 30. The separation enables cross flows to occur through the filter structure 34 during the cardiac cycle that may dislodge emboli from the pores of the mesh 34, with the emboli being returned to the aortic arch and away from the inlets of the arteries.
It is noted that the web portion 252 does not need to be arcuate for to have the beneficial effect described above. The web portion may extend linearly between the rails and provide the same effect, provided that the location of the seating of the rails 222 against the aortic arch 31 provides adequate separation between the mesh 84 and the ostia of the filtered arteries.
The crimps 346 secure the distal end 336 the filter structure 34g to the anchor portion 302, thereby maintaining coverage of the elbow portion 52 with the filter structure 34g. The crimps 346, when including a radiopaque material, serve as a location marker of the junction between the filter structure 34g and the anchor portion 302 that can be viewed with various imaging systems. The crimp 337 of the tail 335 can function as a snare for retrieval of the filter assembly 30g.
The loop 228 assures capture of the filter structure 34g within the support structure 32g. The crimp 258 not only provide closure of the loop 228, but can also facilitate retrieval of the filter assembly 30g. A radiopaque crimp 258, when utilized, serves as a location marker for various imaging systems. The increased cross section of the rails 222 relative to the strands of the mesh 84 enable the rails 222 to support the filter structure 34g and to cause the filter structure 34g to conform to the heat set shape of the rails 222. The cross sections of the rails 222 also provides spring biasing of the filter leg portion 48 for seating against the roof of the aortic arch 31.
Referring to
In general and approximate terms, the lateral projection plane 66 is parallel to the coronal plane of the human body and orthogonal to an anterior direction 412 and posterior direction 414 of the human body. While depictions of the filter assembly 30 in
The depictions of
A roof 416 of the aortic arch 31 presents an arcuate shape. As such, the lateral edges 248 of the filter 34 may also be arcuately shaped to better conform to the profile of the aortic roof 416. Because of the arcuate cross-section 246 of the web portion 252, the seating of the rails against the aortic roof 416 does not put the web portion 252 in apposition with the aortic roof 416. The benefit of such an arrangement is described attendant to filter assembly 30g at
The filter assembly 30 may also accommodate the non-linear arrangement of the ostia of the innominate artery 402, the left carotid artery 404, and the left subclavian artery 406. Generally, the left carotid artery 404 is located further in the anterior direction 412 than is the left subclavian artery 406. Accordingly, the lateral edge portions 248 may arc generally in the posterior direction 414 (
The filter assembly 30 may be configured during fabrication as outlined above and heat set to adopt the stated characteristics in the pre-implant configuration 164. Functionally, the conformance of the filter assembly 30 to the aortic wall prevents emboli from bypassing the filter structure 34 and entering the arteries 402, 404, and 406. The conformance also enables substantial contact along the aortic arch 31 without application of an excessive biasing. Any reduction in the biasing force generally reduces erosion and irritation of the aortic roof 416, and can also reduce distortions of the filter assembly 30.
Each of the disclosed embodiments defines a minimum projected angle θ, which may also be described in reference to the outline 420 of
The minimum projected angle θ of
Each of the additional figures and methods disclosed herein can be used separately, or in conjunction with other features and methods, to provide improved devices and methods for making and using the same. Therefore, combinations of features and methods disclosed herein may not be necessary to practice the disclosure in its broadest sense and are instead disclosed merely to particularly describe representative and preferred embodiments.
Various modifications to the embodiments may be apparent to one of skill in the art upon reading this disclosure. For example, persons of ordinary skill in the relevant arts will recognize that the various features described for the different embodiments can be suitably combined, un-combined, and re-combined with other features, alone, or in different combinations. Likewise, the various features described above should all be regarded as example embodiments, rather than limitations to the scope or spirit of the disclosure.
Persons of ordinary skill in the relevant arts will recognize that various embodiments can comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the claims can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art.
Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
Unless indicated otherwise, references to “embodiment(s)”, “disclosure”, “present disclosure”, “embodiment(s) of the disclosure”, “disclosed embodiment(s)”, and the like contained herein refer to the specification (text, including the claims, and figures) of this patent application that are not admitted prior art. Herein, references to “proximal” and associated derivative terms refer to a direction or position that is toward the surgeon or operator. References to “distal” and associated derivative terms refer to a direction or position that is away from the surgeon or operator.
For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in the respective claim.
This patent application claims the benefit of U.S. Provisional Application No. 62/849,241, filed May 17, 2019, the disclosure of which is incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/033468 | 5/18/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62849241 | May 2019 | US |
