Patent Application
20230355413
The present technology relates generally to medical device systems and methods, and more particularly, to medical device delivery and methods of implantation of stents or flow diverters for the treatment of vascular disease, such as intracranial aneurysm.
Endovascular implantation of scaffolding devices, such as flow diverters, are used to treat aneurysms in vessels of the brain (e.g., cerebral arteries) or vessels leading to the brain (e.g., intracranial arteries). Flow diverters are particularly useful for treating aneurysms with wide necks that are difficult to exclude by other means, such as embolic coils. The flow diverters are targeted to be positioned starting from a distal normal segment, spanning the aneurysm, and ending in a proximal normal segment. Flow diverters are designed to have a very dense material coverage, around 30% when expanded, so as to exclude or limit blood flow from entering the aneurysm through the aneurysm neck. Excluding blood flow into the aneurysm reduces or eliminates the risk of aneurysm rupture due to thrombosis at the site over time.
In general, endovascular implantation of devices in cerebral and intracranial arteries have been performed via smaller-sized delivery systems. Access with larger diameter systems has been challenging due, in part, to the tortuosity of the vasculature in the skull as well as the small size and delicate nature of the vessels. Navigating these arteries to deliver endovascular implants such as flow diverters requires catheter systems having superior flexibility and deliverability, which can be challenging, especially for larger diameter catheters. Due to difficulty in navigating large-diameter delivery systems to these anatomies, flow diverters and other endovascular implants have been typically delivered through microcatheters that have an inner diameter of 0.027″ or smaller. Furthermore, the implants are typically pushed through these catheters rather than being delivered pre-mounted on the distal end of a delivery system, as is standard for self-expanding stents in larger and more accessible locations. This method requires extra steps and wire exchanges, adding to the time and risk of the procedure.
All currently available flow diverters are based on a braided wire design to achieve the high percentage metal coverage that achieves the desired thrombotic effect. A braid design can expand from a diameter deliverable through a 0.027″ inner diameter microcatheter to a vessel having a maximum desired vessel diameter of up to 5 mm (0.2″) while still possessing a metal coverage ratio of 30% at the expanded configuration. Examples include the Medtronic PIPELINE, the Stryker SURPASS, the Terumo FRED, and others. In contrast, stents constructed from laser-cut metal tubes, such as Nitinol, stainless steel, and other alloys are unable to accomplish the desired at least 30% metal coverage ratio due to geometric constraints.
Unfortunately, braid-style flow diverters can be difficult, time-consuming, imprecise, and risky to deliver. One problem with braid-style, self-expanding implants, such as braided flow diverters is that they may not immediately expand fully to the walls of the vessel and therefore may move during deployment, leading to time-consuming and risky maneuvers to achieve the desired wall coverage, location, and wall apposition. Significant shortening of the braided flow diverters is also a problem during deployment due to the nature of braid construction, and often leads to ineffective coverage of the aneurysm site and often requires repositioning, manipulation, or may require placement of an additional implant. Because of this, coverage of the aneurysm and/or apposition of the flow diverter against the wall is often not optimal. Poor apposition is associated with higher rates of narrowing or occlusion of the flow diverter.
Additionally, due to difficulty in navigating large diameter delivery systems to distal carotid and cerebral anatomies, devices such as flow diverters have been typically delivered through microcatheters that are 0.027″ ID or smaller. The delivery system for such devices often includes a leading distal guidewire tip, which presents risk of vessel perforation. Furthermore, braid-style implants like flow diverters terminating in wire ends often require delivery systems with additional distal-end-constraining features to enable the device to be pushed through the microcatheter. This constraining feature adds time and complexity to the deployment procedure.
There is a need for improved flow diverters that can be delivered through larger-bore access systems that are able to optimally access cerebral and intracranial arteries for the treatment of aneurysms at these sites while providing adequate vessel coverage and improved deliverability and expansion characteristics. There is also a need for improved flow diverter delivery systems of flow diverters which are compatible with these larger-bore access devices and which can deliver flow diverters precisely and quickly with minimal steps.
In an aspect, provided is a flow diverter including a self-expanding tubular member having a plurality of expandable cells, each of the expandable cells having interconnected struts and bridges. The tubular member has a constrained configuration having a first outer diameter of at least 1.0 mm sized for delivery using a flow diverter delivery system and an expanded configuration having a second outer diameter larger than the first outer diameter. The tubular member has a proximal end zone, a distal end zone, and a middle zone located between the proximal end zone and the distal end zone. At least the middle zone of the tubular member is laser-cut to have a material coverage of at least 25% when the tubular member is in the expanded configuration.
The interconnected struts and bridges of each expandable cell can include two pairs of struts each strut of the two pairs of struts having an outer edge. The outer edge of a first strut of a first pair can be interconnected to an outer edge of a second strut of the first pair by one of the bridges. The first strut of the first pair of struts can connect at a central bend to a first strut of a second pair of struts and the second strut of the first pair can connect at a central bend to a second strut of the second pair. A circumferential height from the central bend of the first pair to the outer edge of the first pair is Y and an axial distance from the central bend of the first pair to the outer edge of the first pair is X, and wherein a diagonal of a rectangle defined by X and Y can be equal to a length of the first strut. A ratio of the length of the first strut to the circumferential height of the first strut can be between 1 and 5. Each of the pairs of struts can be arranged parallel to one another and spaced an axial distance away from one another thereby defining a V-shaped opening of the expandable cell. The two pairs of struts can be interconnected to form a peak on a first end of the expandable cell and a corresponding valley on a second end of the expandable cell. The plurality of expandable cells can be arranged in circumferential rings and each peak in a circumferential ring of expandable cells can be aligned circumferentially with each peak of an adjacent circumferential ring of expandable cells. A bridge can connect the peak of the expandable cell of a first circumferential ring to a valley of an expandable cell of an adjacent second circumferential ring.
The middle zone can have properties different from one or both of the proximal end zone and distal end zone. The middle zone can have greater material coverage than one or both of the proximal end zone and the distal end zone. One or both of the proximal end zone and the distal end zone can be laser-cut to have a material coverage that is less than the material coverage of the middle zone. The material coverage of the middle zone can be between 25%-35% when the tubular member is in the expanded configuration and the proximal and distal end zones can have a material coverage less than the material coverage of the middle zone. At least one of the proximal end zone, the middle zone, and the distal end zone can include at least one radiopaque marker. A length of the flow diverter in the constrained configuration can be less than 1% different from a length of the flow diverter in the expanded configuration. A length of the flow diverter in the constrained configuration can be less than about 5% different from a length of the flow diverter in the expanded configuration. A length of the flow diverter in the constrained configuration can be less than about 10% different from a length of the flow diverter in the expanded configuration.
The first outer diameter can be between 1.5 mm and 2.5 mm and wherein the second outer diameter is between 2.0 mm and 6.0 mm. A length of the flow diverter in the constrained configuration can be between 10 mm and 35 mm. The plurality of expandable cells of the tubular member can be arranged into between 10 and 50 circumferential rings. A pitch of the middle zone can be between about 0.25 mm-0.40 mm, the pitch corresponding to a length of a bridge of an expandable cell of the middle zone. A pitch of one or both of the proximal end zone and distal end zone can be about 0.45 mm-0.75 mm, the pitch corresponding to a length of a bridge of an expandable cell of the proximal end zone or distal end zone. The plurality of expandable cells can form rows extending between proximal and distal ends of the tubular member parallel with a longitudinal axis of the tubular member, the rows of the expandable cells aligned peak-to-valley. The tubular member can include between 4 and 10 rows.
At least the distal end zone can include a rail formed of bridges interconnecting the plurality of expandable cells within a row. The rail can enable resheathing of the distal end zone in a delivery system after at least partial deployment of the distal end zone. One or both of the proximal end zone and the distal end zone can include a braided or woven construction. The interconnected struts can be connected by hinges in a plurality of V-shapes. A line connecting radially adjacent hinges can pass through at least 4 cells in the middle zone. The line connecting radially adjacent hinges in the proximal and distal zones can pass through fewer cells than in the middle zone. Bridges located in the middle zone can be shorter than bridges located in the distal end zone and proximal end zone. The struts in the middle zone, distal end zone, and proximal end zone can be substantially the same in length and configuration. The bridges can lie parallel to a flow diverter central axis.
In an interrelated aspect, provided is a method of treating intracranial or cerebral aneurysm including advancing a catheter system through a base sheath towards an intracranial or cerebral vessel having a segment with an aneurysm. The catheter system includes an inner catheter having a tubular elongate body with a single lumen and a flexible, distal tapered end region; and an outer catheter having a catheter lumen and a distal end. The method includes positioning the tapered end region of the inner catheter distal to the distal end of the outer catheter; crossing the segment of vessel with the aneurysm with at least a portion of the tapered end region of the inner catheter; advancing the outer catheter over the inner catheter and positioning a distal end region of the outer catheter across the lesion; withdrawing the inner catheter from the catheter lumen and maintaining the outer catheter in place across the aneurysm; advancing a flow diverter delivery system comprising a flow diverter through the catheter lumen to the distal end region of the outer catheter; withdrawing the outer catheter while maintaining the flow diverter delivery system in place; and deploying the flow diverter across the segment with the aneurysm.
In an interrelated aspect, provided is a method of performing a medical procedure at a treatment site in a brain of a patient including positioning a system of devices into an advancement configuration. The system of devices includes a catheter having a catheter lumen, an inner diameter, and a distal end; and an inner member sized and shaped to slide within the catheter lumen. The inner member defines a single lumen and has a distal portion. The distal portion has a first outer diameter that tapers distally to a second outer diameter that is smaller than the first outer diameter, and the inner member transitions in flexibility from a proximal end of the inner member to a distal end of the inner member, the distal end of the inner member being more flexible than the distal end of the catheter. When positioned in an advancement configuration, the inner member extends coaxially through the catheter lumen until the distal portion of the inner member is positioned distal to the distal end of the catheter. The method includes advancing the catheter and the flexible inner member to a target location to an access point of entry while the system of devices is positioned in the advancement configuration; positioning the catheter at the treatment site, the treatment site comprising an aneurysm; removing the inner member from the patient; and treating the aneurysm through the catheter. The step of treating can include delivering a flow diverter to the aneurysm through the catheter.
In an interrelated aspect, provided is a flow diverter delivery system including a flow diverter having a tubular structure and configured to treat an aneurysm in an intracranial vessel, the flow diverter having a constrained configuration having a first outer diameter and an expanded configuration having a second outer diameter; an inner core member including an elongate shaft having a recessed region near a distal end region of the elongate shaft, the recessed region sized to receive the tubular structure of the flow diverter when the flow diverter is in the constrained configuration; and an atraumatic distal tip region located distal to the recessed region. The distal tip region has a taper from a first outer diameter of the elongate shaft to a second outer diameter of the elongate shaft. The first outer diameter of the elongate shaft is larger than an outer diameter of the recessed region. The system includes an outer restraining sleeve having an inner diameter sized to receive the inner core member and the flow diverter in the constrained configuration. The outer restraining sleeve is retractable at least a distance to deploy the flow diverter.
The inner diameter of the restraining sleeve can be size-matched to the first outer diameter of the elongate shaft to reduce an annular space at a leading end of the flow diverter delivery system. The distal tip region can include at least one radiopaque marker at a distal end. The distal tip region can include a second radiopaque marker positioned to identify the taper.
In an interrelated aspect, provided is a flow diverter having a self-expanding tubular member having a proximal end, a distal end, and a longitudinal axis. The tubular member has a constrained configuration with a first outer diameter sized for delivery and an expanded configuration having a second outer diameter larger than the first outer diameter. The tubular member includes a plurality of expandable cells, each cell having interconnected struts and bridges arranged in circumferential rings. The circumferential rings form rows of the expandable cells extending between the proximal and distal ends of the tubular member parallel with the longitudinal axis, the rows of expandable cells nested peak-to-valley. The tubular member has a proximal end zone near the proximal end of the tubular member, a distal end zone near the distal end of the tubular member, and a middle zone located between the proximal end zone and the distal end zone. At least the distal end zone includes at least one rail formed of bridges interconnecting each circumferential ring of expandable cells within a single row.
The at least one rail can enable resheathing of the distal end zone in a delivery system after at least partial deployment of the distal end zone from the delivery system. At least the middle zone of the tubular member can be laser-cut to have a material coverage of at least 25% when the tubular member is in the expanded configuration.
In an interrelated aspect, provided is a flow diverter configured to expand from a constrained state to an expanded state. The flow diverter includes a first tube of superelastic material formed of a plurality of cells having a first material coverage; and a second tube of superelastic material formed of a plurality of cells having a second material coverage. The second tube is positioned inside of the first tube so that an overlap of the plurality of expandable cells of the first tube and the plurality of expandable cells of the second tube forms a third material coverage that is greater than the first material coverage and the second material coverage when the flow diverter is in the expanded state.
The second tube can be locked in position inside the first tube by a feature in a cut pattern of at least one of the first tube and the second tube. The feature can include a slot in the first or the second tube and tab configured to protrude into the slot to lock the first and second tubes together. The feature can include a hole in the first or the second tube and a malleable disk configured to insert within the hole to lock the first and second tubes together. At least one of the first tube and the second tube can be non-braided and laser-cut.
These and other aspects will now be described in detail with reference to the following drawings. Generally, the figures are not to scale in absolute terms or comparatively, but are intended to be illustrative. Also, relative placement of features and elements may be modified for the purpose of illustrative clarity.
It should be appreciated that the drawings are for example only and are not meant to be to scale. The drawings are intended to be illustrative to dimensions including metal coverage percentages. The drawings are not to scale in absolute terms or comparatively. It is to be understood that devices described herein may include features not necessarily depicted in each figure.
Described herein are flow diverters and delivery systems and methods that are compatible with large-bore access systems. The devices, systems and methods take advantage of the large-bore access to provide improvements over existing braided flow diverters and associated microcatheter-based delivery systems to enable more precise, safe, and rapid treatment of aneurysms. These devices and systems can be delivered through any large-bore neurovascular access systems. Also described are improved large-bore access systems that facilitate the speed, safety, and ease of accessing intracranial and cerebral arteries to implant flow diverters at their intended site, even despite navigational challenges.
Where the phrase “access catheter” is used herein that such a catheter may be used for other purposes besides or in addition to access, such as the delivery of fluids to a treatment site or as an aspiration catheter. Alternatively, the access systems described herein may also be useful for access to other parts of the body outside the vasculature. Similarly, where the working device is described as being an expandable cerebral treatment device or flow diverter, other interventional devices can be delivered using the access and delivery systems described herein. As used herein, “an aneurysm” refers to the ballooning out of a weakened section of vessel wall. A “cerebral aneurysm” or “intracranial aneurysm” refers to an aneurysm in a vessel of the brain.
Disclosed herein are flow diverters that greatly improve the deployment and performance compared to current braided-style flow diverters. The flow diverters can be self-expanding, cut-tube style implants that unlike a braided wire tube, expand to full diameter much more quickly and accurately. There is no need to constrain or cover the distal end of the implant because the cut-tube construction lacks wire ends like braided implants do. The cut-tube flow diverters described herein also do not experience significant foreshortening as braided wire scaffolds do. The cut pattern can be designed to achieve wall apposition and coverage sufficient to achieve flow diversion, prevention, or rejection of blood flow into the aneurysm, and/or isolation of an aneurysm, with a single layer of material (as opposed to a braid, with a crossed wire surface), resulting in a smoother and less thrombogenic inner surface.
The constrained outer diameter OD1 of the flow diverter 700 can be about 0.89 mm (0.035″) to about 3 mm (0.118″), preferably about 1.5 mm (0.06″) to 2.5 mm (0.10″), or about 1.60 mm. This constrained outer diameter OD1 is relatively large compared to the constrained outer diameter of a conventional braided-style flow diverters. This is enabled by the larger-bore access system described herein that is configured to reach distal sites for deployment of the flow diverter. The deliverability of the large-bore access system, which will be described in more detail below, is capable of delivering the larger constrained outer diameter OD1 flow diverter, also enables the flow diverter to be designed with greater material coverage when expanded.
The expanded outer diameter OD2 of the flow diverter 700 can be about 2 mm (0.08″) up to about 6 mm (0.24″), preferably between about 2.5 mm (0.10″) and about 5 mm (0.2″), depending on the anatomic requirements. The flow diverter 700, when expanded, is preferably suitable for vessels up to 5 mm in diameter. The flow diverter length L1 can also be manufactured depending on the anatomic requirements. For example, the length L1 of the flow diverter prior to expansion can vary from 10 mm to 50 mm including any dimension between and preferably from 10 mm to 35 mm.
The length L2 of the flow diverter after expansion can be in the same range. The cut-tube-style flow diverters 700 described herein undergo a minimal amount of foreshortening upon deployment from the constrained state to the expanded state in the vessel. This provides an advantage over braided-wire style flow diverters that significantly foreshorten upon deployment. The flow diverter designs shown in
The flow diverter 700, when the tubular member is in the expanded, is capable of achieving a material coverage suitable for treating aneurysms. The material coverage (also referred to herein as material density) can vary, but is generally between about 25%-35% material coverage (+/−5%). “Material coverage” as used herein means the surface area of the outer surface of the flow diverter divided by the surface area of the inner lumen of the vessel. The material of the flow diverter provides the material coverage, which is the inverse of porosity of the flow diverter, which is a function of the amount of open space of the flow diverter upon expansion.
The flow diverter is self-expanding and can be a tubular member having circumferential rings of expandable cells 750. Each of the cells 750 includes interconnected struts and axial bridges.
Each expandable cell 750 with the V-shaped opening 754 forms a valley 753 opening towards the proximal end 709 of the flow diverter 700 and a peak 757 projecting towards the distal end 707 of the flow diverter. The peak 757 is formed by the central bend 758 between two struts 751 and the valley 753 is formed by the central bend 758 of the other two struts 751. The first pair of struts 751 can be connected to one another at a first edge of the cell 750 by a first bridge 752 and the second pair of struts 751 can be connected to one another at the opposite edge of the cell 750 by a second bridge 752. A third bridge 752 can couple the peak 757 of one cell 750 to the valley 753 of an adjacent cell 750, which will be described in more detail below.
The V-shaped openings 754 formed by the struts 751 and connecting bridges 752 can repeat around a circumference of the flow diverter 700 forming one of the plurality of circumferential rings 760. The pattern of cells 750 can repeat along the axial length of the flow diverter 700 a number of times thereby defining the number of rings 760. Depending on the desired overall axial length and density of cells, the flow diverter 700 can include between 10 and 50 rings 760, and any number in between, of zig-zagging V-shaped cells 750 depending on the overall length of the flow diverter 700 and the needs of the anatomy being treated. The pattern of cells 750 can repeat circumferentially around the tubular structure of the flow diverter 700 a number of times thereby defining the number of rows 765. The number of rows 765 may vary depending on the desired dimensions of the flow diverter 700. For the dimensions typical for intracranial and cerebral aneurysm treatment, the number of rows 765 may range from 4 to 10, preferably about 6. Thus, the number of struts 751 around the circumference of the flow diverter, which is twice the number of peaks 753 because four struts 751 pair to create a single cell 750 with a peak 753, can be about 8 to 20, preferably about 12.
Still with respect to
The axial length of these bridges 752 controls the axial spacing between the struts 751 in the cell 750, which is also referred to herein as the pitch P (see
Still with respect to
The bridges 752 are shown as connecting members that are substantially straight and lie parallel to a longitudinal axis of the flow diverter (i.e., central axis). The bridges 752 connect adjacent peaks and valleys to form a cell 750. However, the bridges 752 need not be straight and can also be curved or angled relative to the longitudinal axis of the flow diverter. The bridges 752 also can connect at a location other than a peak to a valley such as connected at a middle of a strut 751 or at a point where a strut 751 meets a hinge (i.e., central bend 758). Further, the bridges 752 are shown aligned and connecting every 2nd pair of struts in a longitudinal direction. However, the bridges need not be axially aligned at all or may be axially aligned at every 3rd, 4th, 5th or other number of strut pairs or cells. Use of the term “axial” herein means in a direction that is along a length of the tubular member of the flow diverter, but does not require the direction to be parallel to the longitudinal axis of the flow diverter. For example, “axial bridge” includes bridges that lie parallel to the central axis of the flow diverter and also bridges that are angled, stepped, or curved relative to the central axis of the flow diverter.
When in the collapsed configuration as shown in
Table 1 below provides example parameters for the flow diverter 700 shown in
Other combinations of parameters may be selected to meet the criteria described above. Other features, such as strut radius, tube wall thickness, may also be selected so that the flow diverter 700 attains the desired physical properties. For example, the strut radius can be about 0.05 mm-0.10 mm, preferably about 0.07 mm and the tube wall thickness may be about 0.05 mm to about 0.09 mm, preferably between 0.065 mm-0.075 mm.
The flow diverter 700 can be designed to have a consistent pattern along its length or can vary in pattern over its length. Still further, the flow diverter 700 can have the same pattern of cells along its entire length, but the pitch of the cells changes depending on the needs of the anatomy. The differences in pattern along the length of the flow diverter 700 can be selected to modify the strength and percent material coverage for optimal performance. The variation in pattern can form different zones along the length of the flow diverter. Again with respect to
The length of the different zones can vary as well. The middle flow diversion zone 701 can have a length Lc designed to be longer or shorter in order to match the needs of the anatomy being treated. As an example, a flow diverter having an overall length L2 of about 20 mm, can incorporate a middle flow diversion zone 701 having a length Lc that is between 10 mm and 15 mm. The flow diverter can have a variety of lengths L2, expanded diameters OD2, and middle zone lengths Lc.
The middle flow diversion zone 701 can be formed by a plurality of rings 760 that are configured to nest tightly with one another, even after expansion, due to the relatively short length of the bridge 752 connecting the peaks 757 and valleys 753 of the cells 750 in adjacent rings 760. The length of the bridge 752 controls the pitch of the cell 750. The greater the length of the bridge 752, the greater the pitch or spacing between struts 751 of the cells 750 and the lower the material density.
Strut width Ws, strut circumferential width Y, and strut axial length X can be the same in all three zones or can vary from one zone to another to vary the pattern density and physical characteristics between the zones. The distal and proximal zones 703, 705 can have one or two axial repetitions or rings 760, the intermediate zones 702, 704 can have two or three axial repetitions or rings 760, and the middle zone 701 can have 10-30 axial repetitions or rings 760.
In an interrelated implementation, the flow diverter 700 may have a different cut pattern at either end to optimize the deployment characteristics resulting in an overall asymmetric design.
Still with respect to
The strut pattern can be varied even within end zones 733 and 734, to optimize the balance between device flexibility and radial strength. For example, as most easily seen in
Further variations may be made along the length of the flow diverter 700. For example,
The design of the distal end can differ from the design of the proximal end of the flow diverter. For example, as seen in
The width, length, number, and location of the axial connection struts can vary, as in axial strut 746 (shown in
The ends of the flow diverter can be flared during manufacture of the device. For example, as seen in
The flare at the proximal end of the flow diverter can be greater than the flare at the distal end of the flow diverter. For example, the angle of the flare at the proximal end can be about 40 degrees and the angle of the flare at the distal end can be about 20 degrees such that the diameter of the opening into the stent lumen on the proximal end can be about 10 mm and the diameter of the opening into the stent on the distal end can be about 7 mm. The outer diameter within a central region of the stent can be about 4.25 mm, in comparison. The length of the flare on the distal and proximal ends can each be about 3-4 mm long and the non-flared uniform OD region can be about 20-23 mm long.
The length of middle flow diversion zone 730 can be about 8 mm-12 mm. The length of each of the end zones 733, 734 can be about 5 mm-10 mm for a total length of about 18 mm-35 mm, preferably about 20 mm-30 mm. The number of nesting struts around the circumference of the stent can be greater than 12 such as about 16 so as to align with 16-strut geometry of the anchor region. The gap between struts in the middle flow diversion zone can be about 33-34 microns.
The flow diverters described herein can incorporate radiopaque marker receptacles 770 (see
The flow diverter 700 can be designed to be at least partially re-sheathable for some distance during the deployment process. As will be described in more detail below with reference to
The cut pattern of the flow diverter 700 determines if the flow diverter is re-sheathable. If the pattern contains features that pop open beyond the inner diameter of the outer restraining sleeve 810, the flow diverter 700 generally cannot be re-sheathed after partial deployment. However, the flow diverters described herein can incorporate features (see rail 775 of
The flow diverter of
The implementations shown in
These multi-layer flow diverter implants 700 utilize the structural stent layer of tube 706 to provide precise placement and anchoring, and the finer stent layer of tube 708 to provide the higher material coverage that diverts the blood from flowing into the excluded aneurysm. The larger-diameter access systems described herein enable delivery of these multi-layer devices, which would not be possible in the current microcatheter delivery methods having smaller inner diameters (e.g., 0.027″), which as described above, are incapable of accommodating a laser-cut flow diverter alone and certainly not a flower diverter plus a restraining sleeve.
The flow diverter 700 can also be made of varying materials and structures along its length. For example, as shown in
The flow diverter implants described herein can be self-expanding tubes or tube components cut to achieve a desired pattern. Any of the cut-tube components in the flow diverters described herein may be self-expanding materials or manufactured from one or more Nitinol laser-cut tubes. The tubes can be Nitinol or another spring material capable of the desired mechanical properties of the self-expanding device.
The tubes or cut tube components can be cut with lasers, mechanically machined, photo-etched by photolithography, or other chemical etching, and the like to achieve the desired cut pattern. As an alternative to cutting the design from cylindrical tubing, the design may be cut or assembled in a planar configuration as a flat pattern and compressed or otherwise wrapped or rolled up into a spiral or cylindrical configuration for delivery, and expanded in situ into a partially cylindrical configuration, a cylindrical configuration, or a partially or fully overlapping roll configuration. In the latter implementation, features might be included to latch or ratchet the flow diverter in the expanded shape. The cut tube could also be manufactured by vapor deposition of material in a tube or flat pattern, the latter to be rolled up.
The cut tubes can undergo finishing processes, such as electropolishing and heat-setting to achieve desired mechanical and dimensional properties. In some implementations, the flow diverter can be heat-shaped to have one or both ends 707, 709 flared to aid in anchoring of the flow diverter to the vessel wall during deployment.
Other materials and manufacturing methods can also be utilized to manufacture flow diverters, as described herein. Alternately, any of the above flow diverter implants may be a balloon-mounted laser cut stents, manufactured from one or more laser-cut stainless steel, cobalt-chromium alloy, or other materials known to be used for balloon-expandable stents. The flow diverters can be fabricated from tubing material including radiopaque materials in addition to the typical constituents of superelastic nickel titanium. For example, the radiopaque material can include platinum, tantalum, tungsten, or gold. The radiopaque material can be homogenously incorporated into the material in an advantageous proportion, or the material can be constructed as a laminate including one or more layers of radiopaque material in addition to one or more layers of nickel titanium, or coated onto the surface of the nickel titanium.
The systems described here is used with a larger-bore access system, and therefore, if desired, the flow diverter may be a braided-wire-style flow diverter in which the braid parameters of the braided-wire-style flow diverter are modified to improve performance. For example, the wire size and/or number of wires can be increased without the design restriction of being deliverable through a 0.021″ or 0.027″ ID microcatheter delivery system as is required with current flow diverters. An example of a current braided flow diverter is the Pipeline Embolization System with 48 wires×30 microns (0.0013″). An increase in wire size would make it incompatible with the 0.027″ ID microcatheter. Flow diverters with higher numbers of braid wires have smaller wire sizes, for example the Surpass Evolve has a 64-wire braid with 0.0011″ wire. Again, an increase in wire size would make it incompatible with the 0.027″ ID microcatheter. In an implementation, the flow diverter 700 is a braided-wire flow diverter constructed from 48 or up to 96 wires or more, with strands of between 35 and 55 micron diameter. These heavier-gauge and/or larger number of wire strand braided flow diverters have a heavier radial force and spring open with more speed than the currently available flow diverters, making them easier to deploy and reducing current issues with braided flow diverters, such as flattening and ribboning during deployment
The flow diverters described herein may have a specialized antithrombotic surface modifications or coatings, for example, heparin coatings, hydrophilic polymer coatings, such as phosphorylcholine and phenox hydrophilic polymers, albumin, fibrin, and the like.
Flow Diverter Delivery Systems
Flow diverters are conventionally mounted on an inner delivery core wire and delivered through a microcatheter having an inner diameter of 0.027″ (0.7 mm). In order to be delivered through such a small-sized delivery system while still providing the desired wall coverage (approximately 30%) when expanded in vessel up to 5.0 mm diameter, flow diverters conventionally have braided wire construction.
The delivery of conventional braided flow diverters typically occurs over several procedural steps. First, a microcatheter is inserted into the vasculature and advanced over a guidewire to a position across the target aneurysm site. The microcatheter tip is often placed far distal to the ultimate target implant site because of the imprecise nature of delivering braid-style flow diverters. Once the microcatheter is in position relative to the target aneurysm, the guidewire is removed. The braided flow diverter is then inserted to the proximal end of the microcatheter using an introducer tube. The flow diverter is pre-mounted on a delivery core wire with features to keep the flow diverter both restrained in the collapsed configuration and secured longitudinally onto the delivery core wire. For example, the core wire can have PTFE sleeves that cover and constrain the braided flow diverter at either end. The core wire often has a distal flexible tip that extends up to 15 mm beyond the distal end of the flow diverter. This means that the distal tip needs to be positioned at least 15 mm beyond the treatment site, and possibly more if the microcatheter is positioned distally, for the flow diverter to be implanted in the correct location, another source of potential complication. The core wire is used to push the flow diverter to the end of the microcatheter. The microcatheter is then retracted to expose the braid, which, by its material properties and construction, begins to spring open. The distal end does not reach its full opening diameter until several millimeters of the braid are exposed due to the nature of the braided construction. The user must often push on the microcatheter while pulling on the core to “push” the braid to its maximum opening in order to get full apposition of the flow diverter against the vessel wall, which is highly desirable to achieve the intended clinical effect. This push and pull technique is yet another potential cause of clinical complication of conventional braided flow diverters as well as adding time to the procedure and imprecision in the implantation location. Braids by their nature shorten considerably upon expansion, making accurate implantation yet more difficult. Often, the flow diverter is delivered distal to the desired site and then partially deployed and “dragged back” into place across the target site. Both the distal positioning of the microcatheter and the “drag back” step are risks for vessel damage and vessel perforation, both leading to severe clinical sequelae.
In many flow diverter delivery systems, the delivery core wire has features that constrain the braid wire ends. The microcatheter following expansion of the flow diverter is fully proximal to the implant and must be re-advanced through the braid to cover the delivery core wire features so that the delivery core wire does not get snagged by the just-deployed flow diverter. Each of these steps potentially disrupt the flow diverter, add to procedural time, and are potential causes of clinical complications due to the extra catheter maneuvering.
The flow diverters described herein can be delivered by flow diverter delivery systems that are larger in diameter and configured to be used with larger-bore access systems compared to conventional braided-style flow diverters. The delivery systems described herein can be used with any of the above flow diverters described previously including laser cut, braided, or woven flow diverters, or combinations thereof.
The materials of the shaft 823 of the inner core member 820 are selected to maintain axial integrity during deployment of the flow diverter 700. For example, the shaft 823 and recessed section 825 can be constructed from Pebax, such as Pebax 72D. The shaft 823 and/or recessed section 825 can be braid-, coil-, or otherwise reinforced to provide axial stiffness.
The length of the outer restraining sleeve 810 is shorter than the inner core member 820 by an amount that allows the flow diverter 700 to be fully deployed when the restraining sleeve 810 is pulled back with respect to the inner core member 820 (see
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The dimensions of the flow diverter 700 and the flow diverter delivery system 800 are sized to be deliverable through a larger-bore access systems. As discussed above, the flow diverter 700 can be a cut-tube design having cells 750 arranged in rings 760 that are connected peak-to-valley. Upon expansion, the flow diverter 700 has a dense material coverage (e.g., 30% coverage or 70% porosity) due to the tightly nested arrangement of the cells 750. The flow diverter 700 can take advantage of the constraint of a larger-bore access system to achieve this dense material coverage. For example, for a distal access system 100 having an access catheter 200 with inner diameter (ID) of 0.088″, the outer restraining sleeve 810 can have an outer diameter (OD) of about 0.082″ leaving an annular clearance of 0.003″ (ID/OD difference of 0.006″) for optimal advancement of the flow diverter delivery system 800 through the access catheter 200. In this example, the ID of the outer restraining sleeve 810 is about 0.070″. The collapsed flow diverter 700 can have an OD of about 0.064″ in order to slide easily through this outer restraining sleeve 810. The inner core member 820 can have an OD of about 0.064″, with the smaller ID recessed section 825 depending on the wall thickness of the flow diverter 700. If the wall thickness of the cut-tube flow diverter 700 is about 0.005″, the recessed section 825 has an OD of about 0.054″.
Larger access systems allow for alternate delivery methodologies. For example, rather than first placing a microcatheter across the aneurysm, removing the guidewire, and then pushing the flow diverter into place as with conventional flow diverter delivery systems, the flow diverters 700 described herein can be pre-mounted onto the delivery system 800 with the restraining sleeve 810, and delivered to the site through a larger delivery system (e.g., 0.087″-0.126″ ID). The guidewire, flow diverter 700, and inner core member 820 can all be pre-mounted in one system rather than exchanging the guidewire for the flow diverter and inner core member as in conventional systems.
In some implementations, the access catheter 200 acts as the restraining sleeve for the flow diverter delivery system 800 in place of a separate restraining sleeve 810. The flow diverter 700 can be mounted on the inner core member 820 and introduced into the access system 100 via a separate introducer component and pushed via advancement of the inner core member 820 to the target aneurysm treatment site in the same manner as current flow diverters may be introduced into microcatheters previously positioned across the target site. In this example, the access catheter 200 can be previously positioned across the target site. Once the flow diverter 700 is positioned at its target site, the inner core member 820 can be held in place while the access catheter 200 is pulled back to deploy flow diverter 700. In this example, there is one “layer” of catheters that is eliminated (i.e., the restraining sleeve 810). This allowed for a larger inner diameter for a same size flow diverter. The flow diverter having an outer diameter of 0.064″ can be delivered using an access catheter having an inner diameter of 0.070″ and an outer diameter of 0.082″ (vs. ID 0.088″ and OD 0.100″ of the previous example).
The flow diverters and flow diverter delivery systems described above can be delivered using an access system and/or access catheter with an appropriately large-bore inner diameter and the ability to reach the target aneurysm treatment site. Current access devices, i.e., guide catheters and/or guide sheaths, are used to access neurovascular anatomy with limitations.
Guide catheters or guide sheaths are used to guide interventional devices to the target anatomy from an arterial access site, typically the femoral artery. The length of the guide is determined by the distance between the access site and the desired location of the guide distal tip. Interventional devices, such as guidewires, microcatheters, and intermediate catheters used for sub-selective guides, are inserted through the guide and advanced to the target site. Often, devices are used in a co-axial fashion, namely, a guidewire inside a microcatheter inside an intermediate catheter, and advanced as an assembly to the target site in a step-wise fashion with the inner, most atraumatic elements, advancing distally first and providing support for advancement of the outer elements. The length of each element of the coaxial assemblage takes into account the length of the guide, the length of proximal connectors on the catheters, and the length needed to extend from the distal end.
Typical tri-axial systems, such as for delivery of flow diverters, stents, stent retrievers and other interventional devices, require overlapped series of catheters, each with their own rotating hemostatic valves (RHV) on the proximal end. For example, a guidewire can be inserted through a Penumbra VELOCITY microcatheter having a first proximal RHV, which can be inserted through a Penumbra ACE68 having a second proximal RHV, which can be inserted through a Penumbra NEURONMAX 088 access catheter having a third proximal RHV positioned in the high carotid via a femoral introducer. Maintaining the coaxial relationships between these catheters can be technically challenging. The three RHVs must be constantly adjusted with two hands or, more commonly, four hands (i.e., two operators). Further, the working area of typical tri-axial systems for intracranial and cerebral device delivery can require working area of 3-5 feet at the base of the operating table. Time is required to access the treatment site using tri-axial systems.
There is also difficulty in getting larger-bore access catheters and sheaths in a rapid and atraumatic fashion to intracranial and cerebral vessels. Both the lengths and diameters of current systems put limitations on the delivery system of endovascular scaffolding devices, such as stents, or flow diverters, which in turn limits the safety, speed, and precision of delivering such devices. There is a need for a system of devices and methods that allow for rapid access of distal intracranial and cerebral vessels with larger lumen sizes and/or shorter lengths.
The access systems and methods described herein enable safe and rapid positioning of large interventional devices, such as flow diverter delivery systems, to an aneurysm site in an intracranial or cerebral artery. Further, the extreme flexibility and deliverability of the distal access catheter systems described herein allow the catheters to take the shape of the tortuous anatomy rather than exert straightening forces creating new anatomy. The distal access catheter systems described herein can pass through tortuous loops while maintaining the natural curves of the anatomy therein decreasing the risk of vessel straightening. The distal access catheter systems described herein can thereby create a safe conduit through the neurovasculature maintaining the natural tortuosity of the anatomy for other catheters to traverse (e.g. interventional device delivery catheters). The catheters traversing the conduit need not have the same degree of flexibility and deliverability such that if they were delivered directly to the same anatomy rather than through the conduit, would lead to straightening, kinking, or folding of the anterior circulation.
Provided herein are access systems including a catheter advancement element having a tapered distal end region with a flexibility, shape, and taper length configured to be atraumatically delivered to a vessel in the brain. This is not achieved with conventional catheter systems as they may have improper flexibility, are formed of improper materials, or have improper shape and/or taper length resulting in conventional catheter systems getting misdirected or hung up or, if more force is applied, perforating the vessel. Unlike these conventional catheter systems, the catheter systems described herein includes a catheter advancement element capable of safely navigating neurovascular anatomy and find the lumen so that a corresponding large bore catheter (i.e., flow diverter delivery system) can be delivered to distal sites. The catheter systems described herein help locate occlusions in the vessels in the novel manner of the methods provided herein. These and other features will be described in detail herein.
The system 100 can include one or more catheter systems 150, each having a catheter 200 and a catheter advancement element 300. The catheter system 150 is configured to be advanced through an access guide sheath 400. The catheter 200 is configured to be received through the guide sheath 400 and is designed to have exceptional deliverability. The catheter 200 can, but need not, be a distal access catheter having a distal tubular component coupled to a smaller outer diameter proximal control element. The distal tubular component being co-axial with a lumen of the guide sheath 400 provides a step-up in inner diameter within the conduit. The catheter need not include the proximal control element and instead can be a conventional, full-length catheter having a uniform diameter.
The catheter 200 can be delivered using a catheter advancement element 300 inserted through a lumen 223 of the catheter 200. The flexibility and deliverability of the distal access catheter 200 allow the catheter 200 to take the shape of the tortuous anatomy and avoids exerting straightening forces creating new anatomy. The distal access catheter 200 is capable of this even in the presence of the catheter advancement element 300 extending through its lumen. Thus, the flexibility and deliverability of the catheter advancement element 300 is on par or better than the flexibility and deliverability of the distal luminal portion 222 of the distal access catheter 200 in that both are configured to reach the middle cerebral artery (MCA) circulation without straightening out the curves of the anatomy along the way.
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The sheath body 402 can extend from a proximal furcation or rotating hemostatic valve (RHV) 434 at a proximal end region 403 to a distal end opening 408 of the body 402. The proximal RHV 434 may include one or more lumens 412 molded into a connector body to connect to the working lumen of the body 402 of the guide sheath 400. The working lumen can receive the catheter 200 and/or any of a variety of working devices for delivery to a target anatomy. The RHV 434 can be constructed of thick-walled polymer tubing or reinforced polymer tubing. The RHV 434 allows for the introduction of devices through the guide sheath 400 into the vasculature, while preventing or minimizing blood loss and preventing air introduction into the guide sheath 400. The RHV 434 can be integral to the guide sheath 400 or the guide sheath 400 can terminate on a proximal end in a female Luer adaptor to which a separate hemostasis valve component, such as a passive seal valve, a Tuohy-Borst valve or RHV may be attached. The RHV 434 can have an adjustable opening that is open large enough to allow removal of devices that have adherent clot on the distal end opening 408 without causing the clot to dislodge at the RHV 434 during removal. Alternately, the RHV 434 can be removable, such as when a device is being removed from the sheath 400, to prevent clot dislodgement at the RHV 434. The RHV 434 can be a dual RHV or a multi-head RHV.
Contrast agent can be injected through the guide sheath 400 into the vessel to visualize the occlusion site by angiogram. For example, the guide sheath 400 can be positioned so that at least a portion is positioned within the carotid artery. The contrast agent may be injected through the sheath 400 once positioned in this location. Contrast agent can also be injected through one or more catheters inserted through the guide sheath 400. A baseline angiogram can be obtained, for example in the anterior/posterior (AP) and/or lateral views, prior to device insertion to assess occlusion location by injection of contrast media through the sheath 400 with fluoroscopic visualization. Fluoroscopic visualization may continue as the catheter system is advanced and subsequent angiograms can be captured periodically to assess reperfusion. The baseline angiogram image can be superimposed, such as with digital subtraction angiography, so that the vasculature and/or occlusion site are visible while the catheter system is advanced.
Once the catheter system 150 is advanced into position (the positioning will be described in more detail below), the catheter advancement element 300 can be withdrawn and removed from the system. In some implementations, the catheter 200 can be used as a support catheter to deliver a stent or flow diverter to the treatment site (e.g., within the carotid or a cerebral artery) as will be described elsewhere herein.
In an implementation, the guide sheath 400 includes one or more radiopaque markers 411. The radiopaque markers 411 can be disposed near the distal end opening 408. For example, a pair of radiopaque bands may be provided. The radiopaque markers 411 or markers of any of the system components can be swaged, painted, embedded, or otherwise disposed in or on the body. In some implementations, the radiopaque markers include a barium polymer, tungsten polymer blend, tungsten-filled or platinum-filled marker that maintains flexibility of the devices and improves transition along the length of the component and its resistance to kinking. In some implementations, the radiopaque markers are a tungsten-loaded PEBAX or polyurethane that is heat welded to the component.
The guide sheath markers 411 are shown in the figures as rings around a circumference of one or more regions of the body 402. However, the markers 411 can have other shapes or create a variety of patterns that provide orientation to an operator regarding the position of the distal opening 408 within the vessel. Accordingly, an operator may visualize a location of the distal opening 408 under fluoroscopy to confirm that the distal opening 408 is directed toward a target anatomy where a catheter 200 is to be delivered. For example, radiopaque marker(s) 411 allow an operator to rotate the body 402 of the guide sheath 400 at an anatomical access point, e.g., a groin of a patient, such that the distal opening provides access to an ICA by subsequent working device(s), e.g., catheters and wires advanced to the ICA. In some implementations, the radiopaque marker(s) 411 include platinum, gold, tantalum, tungsten or any other substance visible under an x-ray fluoroscope. Any of the various components of the systems described herein can incorporate radiopaque markers.
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A single, inner lumen 223 extends through the luminal portion 222 between a proximal end and a distal end of the luminal portion 222 (the lumen 223 is visible in
The distal luminal portion 222 of the catheter 200 can have one or more radiopaque markings 224. A first radiopaque marker 224a can be located near the distal-most end 215 to aid in navigation and proper positioning of the distal-most end 215 under fluoroscopy. Additionally, a proximal region of the catheter 200 may have one or more proximal radiopaque markers 224b so that the overlap region 348 can be visualized as the relationship between a radiopaque marker 411 on the guide sheath 400 and the radiopaque marker 224b on the catheter 200. The proximal region of the catheter 200 may also have one or more radiopaque markings providing visualization, for example, near the proximal opening 242 into the single lumen 223 of the catheter 200 as will be described in more detail below. In an implementation, the two radiopaque markers (marker 224a near the distal-most end 215 and a more proximal marker 224b) are distinct to minimize confusion of the fluoroscopic image, for example the catheter proximal marker 224b may be a single band and the marker 411 on the guide sheath 400 may be a double band and any markers on a working device delivered through the distal access system can have another type of band or mark. The radiopaque markers 224 of the distal luminal portion 222, particularly those near the distal end region navigating extremely tortuous anatomy, can be relatively flexible such that they do not affect the overall flexibility of the distal luminal portion 222 near the distal end region. The radiopaque markers 224 can be tungsten-loaded or platinum-loaded markers that are relatively flexible compared to other types of radiopaque markers used in devices where flexibility is not paramount. In some implementations, the radiopaque marker can be a band of tungsten-loaded PEBAX having a durometer of Shore A 35D.
The proximal control element 230 can include one or more markers 232 to indicate the overlap between the distal luminal portion 222 of the catheter 200 and the sheath body 402 as well as the overlap between the distal luminal portion 222 of the catheter 200 and other interventional devices that may extend through the distal luminal portion 222. At least a first mark can be an RHV proximity marker positioned so that when the mark is aligned with the sheath proximal hemostasis valve 434 during insertion of the catheter 200 through the guide sheath 400, the catheter 200 is positioned at the distal-most position with the minimal overlap length needed to create the seal between the catheter 200 and the working lumen. At least a second marker 232 can be a Fluoro-saver marker that can be positioned on the control element 230 and located a distance away from the distal-most end 215 of the distal luminal portion 222. In some implementations, a marker 232 can be positioned about 100 cm away from the distal-most end 215 of the distal luminal portion 222. The markers 232 can be positioned on the catheter so that one or more markers are visible to an operator outside the patient (and outside the guide sheath 400) during use. One or more markers can also be visible to an operator inside the patient (and inside the guide sheath 400 or beyond a distal end of the guide sheath 400) during use such that they are visualized under fluoroscopy.
The catheter 200 shown in
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The configuration of the proximal portion 366 can vary. In some implementations, the proximal portion 366 is simply a proximal extension of the flexible elongate body 360 that does not change significantly in structure but changes in flexibility. For example, the proximal portion 366 transitions from the very flexible distal regions of the catheter advancement element 300 towards less flexible proximal regions of the catheter advancement element 300. In some implementations, the proximal portion 366 can provide a relatively stiff proximal end suitable for manipulating (e.g., advancing and withdrawing) the more distal regions of the catheter advancement element 300 relative to the anatomy and/or the outer catheter 200. The proximal portion 366 can be formed of a less flexible polymer than the flexible elongate body. The proximal portion 366 can be fully polymeric having no reinforcement or the proximal portion 366 can be a reinforced polymer portion. The configuration of the proximal portion 366 can vary depending on whether the catheter advancement element 300 is to be used with a full-length catheter or a catheter having only a short distal tubular portion. The catheter advancement element 300 used with a full-length catheter need not rely upon a proximal reinforcement in order to advance the catheter system through the anatomy and can instead rely on the proximal stiffness of the outer catheter. A catheter advancement element 300 used with a partial tube outer catheter may benefit from a stiffer reinforcement within its proximal end region for advancing the system.
In some implementations, the proximal portion 366 is a metal reinforced segment. The metal reinforced segment can be positioned a distance away from the distal end of the elongate body. For example, the metal reinforced segment can be about 50 cm from the distal end. The metal reinforced segment can have an inner diameter of about 0.021″ and an outer diameter of about 0.027″. The metal reinforced segment can be a spine. The metal reinforced segment can be a hypotube. In other implementations, the proximal portion 366 is a hypotube. The hypotube may be exposed or may be coated by a polymer. In still further implementations, the proximal portion 366 may be a tubular polymer portion reinforced by a coiled ribbon or braid. The proximal portion 366 can have the same outer diameter as the flexible elongate body or can have a smaller outer diameter as the flexible elongate body.
The proximal portion 366 need not include a lumen. For example, the proximal portion 366 can be a solid rod, ribbon, or wire have no lumen extending through it that couples to the tubular elongate body 360. Where the proximal portion 366 is described herein as having a lumen, it should be appreciated that the proximal portion 366 can also be solid and have no lumen. The proximal portion 366 is generally less flexible than the elongate body 360 and can transition to be even more stiff towards the proximal-most end of the proximal portion 366. Thus, the catheter advancement element 300 can have an extremely soft and flexible distal end region 346 that transitions proximally to a stiff proximal portion 366 well suited for pushing and/or torqueing the distal elongate body 360.
The elongate body 360 can be received within and extended through the internal lumen 223 of the distal luminal portion 222 of the catheter 200 (see
As will be described in more detail below, the catheter advancement element 300 can also include a distal end region 346 located distal to the at least one snug point of the tubular portion. The distal end region 346 can have a length and taper along at least a portion of the length. The distal end region 346 of the catheter advancement element 300 can be extended beyond the distal end of the catheter 200 as shown in
The overall length of the catheter advancement element 300 (e.g. between the proximal end through to the distal-most tip) can vary, but generally is long enough to extend through the support catheter 200 plus at least a distance beyond the distal end of the support catheter 200 while at least a length of the proximal portion 366 remains outside the proximal end of the guide sheath 400 and outside the body of the patient. In some implementations, the overall length of the catheter advancement element 300 is about 145 to about 150 cm and has a working length of about 140 cm to about 145 cm from a proximal tab or hub to the distal-most end 325. The elongate body 360 can have a length that is at least as long as the luminal portion 222 of the catheter 200 although the elongate body 360 can be shorter than the luminal portion 222 so long as at least a minimum length remains inside the luminal portion 222 when a distal portion of the elongate body 360 is extended distal to the distal end of the luminal portion 222 to form a snug point or snug region with the catheter. In some implementations, this minimum length of the elongate body 360 that remains inside the luminal portion 222 when the distal end region 346 is positioned at its optimal advancement configuration is at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm up to about 50 cm. In some implementations, the shaft length of the distal luminal portion 222 can be about 35 cm up to about 75 cm and shorter than a working length of the guide sheath and the insert length of the elongate body 360 can be at least about 45 cm, 46 cm, 47 cm, 48 cm, 48.5 cm, 49 cm, 49.5 cm up to about 85 cm.
The length of the elongate body 360 can allow for the distal end of the elongate body 360 to reach cerebrovascular targets or occlusions within, for example, segments of the internal carotid artery including the cervical (C1), petrous (C2), lacerum (C3), cavernous (C4), clinoid (C5), ophthalmic (C6), and communicating (C7) segments of the internal carotid artery (ICA) as well as branches off these segments including the M1 or M2 segments of the middle cerebral artery (MCA), anterior cerebral artery (ACA), anterior temporal branch (ATB), and/or posterior cerebral artery (PCA). The distal end region of the elongate body 360 can reach these distal target locations while the proximal end region of the elongate body 360 remains proximal to or below the level of severe turns along the path of insertion. For example, the entry location of the catheter system can be in the femoral artery and the target occlusion location can be distal to the right common carotid artery, such as within the M1 segment of the middle cerebral artery on the right side. The proximal end region of the elongate body 360 where it transitions to the proximal portion 366 can remain within a vessel that is proximal to severely tortuous anatomy, such as the carotid siphon, the right common carotid artery, the brachiocephalic trunk, the take-off into the brachiocephalic artery from the aortic arch, the aortic arch as it transitions from the descending aorta. This avoids inserting the stiffer proximal portion 366, or the material transition between the stiffer proximal portion 366 and the elongate body 360, from taking the turn of the aortic arch or the turn of the brachiocephalic take-off from the aortic arch, which both can be very severe. The lengths described herein for the distal luminal portion 222 also can apply to the elongate body 360 of the catheter advancement element.
The proximal portion 366 can have a length that varies as well. In some implementations, the proximal portion 366 is about 90 cm up to about 95 cm. The distal portion extending distal to the distal end of the luminal portion 222 can include distal end region 346 that protrudes a length beyond the distal end of the luminal portion 222 during use of the catheter advancement element 300. The distal end region 346 of the elongate body 360 that is configured to protrude distally from the distal end of the luminal portion 222 during advancement of the catheter 200 through the tortuous anatomy of the cerebral vessels, as will be described in more detail below. The proximal portion 366 coupled to and extending proximally from the elongate body 360 can align generally side-by-side with the proximal control element 230 of the catheter 200. The arrangement between the elongate body 360 and the luminal portion 222 can be maintained during advancement of the catheter 200 through the tortuous anatomy to reach the target location for treatment in the distal vessels and aids in preventing the distal end of the catheter 200 from catching on tortuous branching vessels, as will be described in more detail below.
In some implementations, the elongate body 360 can have a region of relatively uniform outer diameter extending along at least a portion of its length and the distal end region 346 tapers down from the uniform outer diameter. The outer diameter of the elongate body 360 also can taper or step down in outer diameter proximally, for example near where the elongate body 360 couples or transitions to the proximal portion 366. The outer diameter of the elongate body 360 need not change in outer diameter near where the elongate body 360 couples or transitions to the proximal portion 366. In some implementations, the region of relatively uniform outer diameter can extend along a majority of the working length of the catheter advancement element 300 including the proximal portion 366. This first region of uniform outer diameter can transition to a second region of uniform outer diameter located distal to the first region. The transition can incorporate a smooth taper or step change in outer diameter between the two regions. The second region of uniform outer diameter having the larger size and located distal to the first region can be useful in filling a lumen of a larger bore catheter without the entire working length of the elongate body needing to have this larger size. In this implementation, the elongate body 360 can have a distal taper changing in diameter from the second uniform diameter region towards the distal opening and a proximal taper changing in diameter from the second uniform diameter region towards the first region of uniform outer diameter.
Depending upon the inner diameter of the catheter 200, the difference between the inner diameter of catheter 200 and the outer diameter of the elongate body 360 along at least a portion of its length, such as at least 10 cm of its length, preferably at least 15 cm of its length can be no more than about 0.015″ (0.381 mm), such as within a range of about 0.003″-0.015″ (0.0762 mm-0.381 mm) or between 0.006″-0.010″ (0.1524 mm-0.254 mm). Thus, the clearance between the catheter 200 and the elongate body 360 can result in a space on opposite sides that is no more than about 0.008″ (0.2032 mm), or can be no more than about 0.005″ (0.127 mm), for example, from about 0.001″ up to about 0.006″ (0.0254 mm-0.1524 mm), preferably about 0.002″ to about 0.005″ (0.0508 mm-0.127 mm), and more preferably about 0.003″ to about 0.005″ (0.0762 mm-0.0508 mm).
The catheter advancement element 300 has a large outer diameter and a relatively small inner diameter, particularly when a guidewire extends into or through the lumen of the catheter advancement element 300. The elongate body 360 can have an overall shape profile from proximal end to distal end that transitions from a first outer diameter having a first length to a tapering outer diameter having a second length. The first length of this first outer diameter region (i.e. the snug-fitting region between the distal luminal portion 222 and the elongate body 360) can be at least about 5 cm, or 10 cm, up to about 50 cm. In other implementations, the snug-fitting region can extend from the proximal tab or luer 364 substantially to the tapered distal end region 346 which depending on the length of the catheter advancement element 300, can be up to about 170 cm. The length of the tapering outer diameter of the distal end region 346 can be about 0.5 cm to about 5 cm, about 1 cm to about 4 cm, or about 1.5 cm to about 3 cm, or between 2.0 cm and about 2.5 cm. In some implementations, the length of the distal end region 346 varies depending on the inner diameter of the catheter 200 with which the catheter advancement element 300 is to be used. For example, the length of the distal end region 346 can be shorter (e.g. 1.2 cm) for a catheter advancement element 300 sized to be used with a catheter 200 having an inner diameter of about 0.054″ (1.372 mm) and can be longer (e.g. 2.5 cm) for a catheter advancement element 300 sized to be used with a catheter 200 having an inner diameter of about 0.088″ (2.235 mm). The distal end region 346 can be a constant taper from the larger outer diameter of the elongate body 360 (e.g. the distal end of the marker 344b) down to a second smaller outer diameter at the distal-most terminus (e.g. the proximal end of the marker 344a) as shown in
The distal end region 346 of the elongate body 360 can also be shaped with or without a taper. When the catheter advancement element 300 is inserted through the catheter 200, this distal end region 346 is configured to extend beyond and protrude out through the distal-most end 215 of the luminal portion 222 whereas the more proximal region of the body 360 (i.e. the first length described above) remains within the luminal portion 222.
As mentioned, the distal-most end 215 of the luminal portion 222 can be blunt and have no change in the dimension of the outer diameter whereas the distal end region 346 can be tapered providing an overall elongated tapered geometry of the catheter system. The outer diameter of the elongate body 360 also approaches the inner diameter of the luminal portion 222 such that the step-up from the elongate body 360 to the outer diameter of the luminal portion 222 is minimized. Minimizing this step-up prevents issues with the lip formed by the distal end of the luminal portion 222 catching on the tortuous neurovasculature, such as around the carotid siphon near the ophthalmic artery branch, when the distal end region 346 in combination with the distal end region of the catheter 200 bends and curves along within the vascular anatomy. In some implementations, the inner diameter of the luminal portion 222 can be at least about 0.052″ (1.321 mm), about 0.054″ (1.372 mm) and the maximum outer diameter of the elongate body 360 can be about 0.048″ (1.219 mm) such that the difference between them is about 0.006″ (0.1524 mm). In some implementations, the inner diameter of the luminal portion 222 can be about 0.070″ (1.778 mm) and the maximum outer diameter of the elongate body 360 can be about 0.062″ (1.575 mm) such that the difference between them is about 0.008″ (0.2032 mm). In some implementations, the inner diameter of the luminal portion 222 can be about 0.088″ (2.235 mm) and the maximum outer diameter of the elongate body 360 can be about 0.080″ (2.032 mm) such that the difference between them is about 0.008″ (0.2032 mm). In some implementations, the inner diameter of the luminal portion 222 can be about 0.072″ (1.829 mm) and the maximum outer diameter of the elongate body 360 is about 0.070″ (1.778 mm) such that the difference between them is only 2 thousandths of an inch (0.002″/0.0508 mm). In other implementations, the maximum outer diameter of the elongate body 360 is about 0.062″ (1.575 mm) such that the difference between them is about 0.010″ (0.254 mm). Despite the outer diameter of the elongate body 360 extending through the lumen of the luminal portion 222, the luminal portion 222 and the elongate body 360 extending through it in co-axial fashion are flexible enough to navigate the tortuous anatomy leading to the level of M1 or M2 arteries without kinking and without damaging the vessel. It is preferred to deliver a catheter that is as large in inner diameter for the passage of larger-sized flow diverter delivery systems.
The dimensions provided herein are approximate and each dimensions may have an engineering tolerance or a permissible limit of variation. Use of the term “about,” “approximately,” or “substantially” are intended to provide such permissible tolerance to the dimension being referred to. Where “about” or “approximately” or “substantially” is not used with a particular dimension herein that that dimension need not be exact.
The elongate body 360 of the catheter advancement element 300 can have a lumen 368 with an inner diameter that does not change over the length of the elongate body even in the presence of the tapering of the distal end region 346. Thus, the inner diameter of the lumen 368 extending through the tubular portion of the catheter advancement element 300 can remain uniform and the wall thickness of the distal end region 346 can decrease to provide the taper. The wall thickness can thin distally along the length of the taper. Thus, the material properties in combination with wall thickness, angle, length of the taper can all contribute to the overall maximum flexibility of the distal-most end of the distal end region 346. The catheter advancement element 300 undergoes a transition in flexibility from the distal-most end towards the snug point where it achieves an outer diameter that is no more than about 0.010″ (0.254 mm) different from the inner diameter of the catheter 200.
The inner diameter of the elongate body 360 can be constant along its length even where the single lumen passes through the tapering distal end region 346. Alternatively, the inner diameter of the elongate body 360 can have a first size through the tapering distal end region 346 and a second, larger size through the cylindrical section of the elongate body 360. The cylindrical section of the elongate body 360 can have a constant wall thickness or a wall thickness that varies to a change in inner diameter of the cylindrical section. As an example, the outer diameter of the cylindrical section of the elongate body 360 can be about 0.080″. The inner diameter of the elongate body 360 within the cylindrical section can be uniform along the length of the cylindrical section and can be about 0.019″. The wall thickness in this section, in turn, can be about 0.061″. As another example, the outer diameter of the cylindrical section of the elongate body 360 can again be between about 0.080″. The inner diameter of the elongate body 360 within the cylindrical section can be non-uniform along the length of the cylindrical section and can step-up from a first inner diameter of about 0.019″ to a larger second inner diameter of about 0.021″. The wall thickness, in turn, can be about 0.061″ at the first inner diameter region and about 0.059″ at the second inner diameter region. The wall thickness of the cylindrical portion of the elongate body 360 can be between about 0.050″ to about 0.065″. The wall thickness of the tapered distal end region 346 near the location of the proximal marker band can be the same as the cylindrical portion (between about 0.050″ and about 0.065″) and become thinner towards the location of the distal marker band. As an example, the inner diameter at the distal opening from the single lumen can be about 0.020″ and the outer diameter at the distal opening (i.e. the outer diameter of the distal marker band) and be about 0.030″ resulting in a wall thickness of about 0.010″ compared to the wall thickness of the cylindrical portion that can be up to about 0.065″. Thus, the outer diameter of the distal tip 346 can taper as can the wall thickness. A wall thickness of the intermediate segment and an un-tapered portion of the tip segment can be about 0.050″ to about 0.065″. The wall thickness of the intermediate segment and the un-tapered portion can be constant. The inner diameter of the intermediate segment and the tapered end region can be constant.
A tip segment of the flexible elongate body can have a tapered portion that tapers distally from a first outer diameter to a second outer diameter. The second outer diameter can be about ½ of the first outer diameter. The second outer diameter can be about 40% of the first outer diameter. The second outer diameter can be about 65% of the first outer diameter. The first outer diameter can be about 0.062″ up to about 0.080″. The second outer diameter can be about 0.031″. The second outer diameter can be about 50% of the first outer diameter, about 40% of the first outer diameter, or about 65% of the first outer diameter.
The length of the taper can also vary depending on the anatomy of the target region. The distal end region 346 can achieve its soft, atraumatic and flexible characteristic due to a material property other than due to a change in outer dimension to facilitate endovascular navigation to an occlusion in tortuous anatomy. Additionally or alternatively, the distal end region 346 of the elongate body 360 can have a transition in flexibility along its length. The most flexible region of the distal end region 346 can be its distal terminus. Moving along the length of the distal end region 346 from the distal terminus towards a region proximal to the distal terminus. For example, the distal end region 346 can be formed of a material having a Shore material hardness of no more than 35D or about 62A and transitions proximally to be less flexible near where it is formed of a material having a material hardness of no more than 55D and 72D up to the proximal portion 366, which can be a stainless steel hypotube, or a combination of a material property and tapered shape. The materials used to form the regions of the elongate body 360 can include PEBAX (such as PEBAX 25D, 35D, 55D, 69D, 72D) or a blend of PEBAX (such as a mix of 25D and 35D, 25D and 55D, 25D and 72D, 35D and 55D, 35D and 72D, 55D and 72D, where the blend ratios may range from 0.1% up to 50% for each PEBAX durometer), with a lubricious additive compound, such as Mobilize (Compounding Solutions, Lewiston, Maine). In some implementations, the material used to form a region of the elongate body 360 can be Tecothane 62A. Incorporation of a lubricious additive directly into the polymer elongate body means incorporation of a separate lubricious liner, such as a Teflon liner, is unnecessary. This allows for a more flexible element that can navigate the distal cerebral anatomy and is less likely to kink. Similar materials can be used for forming the distal luminal portion 222 of the catheter 200 providing similar advantages. The flexibility of the distal end region 346 can be achieved by a combination of flexible lubricious materials and tapered shapes. For example, the length of the distal end region 346 can be kept shorter than 2 cm-3 cm, but maintain optimum deliverability due to a change in flexible material from distal-most end 325 towards a more proximal region a distance away from the distal-most end 325. In an implementation, the elongate body 360 is formed of PEBAX (polyether block amide) embedded silicone designed to maintain the highest degree of flexibility. The wall thickness of the distal end of the luminal portion 222 can also be made thin enough such that the lip formed by the distal end of the luminal portion 222 relative to the elongate body 360 is minimized.
The elongate body 360 has a benefit over a microcatheter in that it can have a relatively large outer diameter that is just 0.003″-0.010″ (0.0762 mm-0.254 mm) smaller than the inner diameter of the distal luminal portion 222 of the catheter 200 and still maintain a high degree of flexibility for navigating tortuous anatomy. When the gap between the two components is too tight (e.g. less than about 0.003″ (0.0762 mm), the force needed to slide the catheter advancement element 300 relative to the catheter 200 can result in damage to one or both of the components and increases risk to the patient during the procedure. The gap results in too tight of a fit to provide optimum relative sliding. When the gap between the two components is too loose (e.g. greater than about 0.010″/0.254 mm), the distal end of the catheter 200 forms a lip that is prone to catch on carotid dissections or branching vessels during advancement through tortuous neurovasculature, such as around the carotid siphon where the ophthalmic artery branches off and the piston effect of withdrawal of the elongate body 360 can be decreased or lost.
The gap in ID/OD between the elongate body 360 and the distal luminal portion 222 can be in this size range (e.g. 0.003″-0.015″ (0.0762 mm-0.381 mm) or between 0.006″-0.010″ (0.152 mm-0.254 mm)) along a majority of their lengths. For example, the elongate body 360 can have a relatively uniform outer diameter that is between about 0.048″ (1.219 mm) to about 0.080″ (2.032 mm) from a proximal end region to a distal end region up to a point where the taper of the distal end region 346 begins. Similarly, the distal luminal portion 222 of the catheter 200 can have a relatively uniform inner diameter that is between about 0.054″ (1.372 mm) to about 0.088″ (2.235 mm) from a proximal end region to a distal end region. As such, the difference between their respective inner and outer diameters along a majority of their lengths can be within this gap size range of 0.003″ to 0.015″ (0.0762 mm-0.381 mm). The distal end region 346 of the elongate body 360 that is tapered will have a larger gap size relative to the inner diameter of the distal luminal portion 222. During use, however, this tapered distal end region 346 is configured to extend distal to the distal end of the catheter 200 such that the region of the elongate body 360 having an outer diameter sized to match the inner diameter of the distal luminal portion 222 is positioned within the lumen of the catheter 200 such that it can minimize the lip at the distal end of the catheter 200.
The elongate body 360 can be formed of various materials that provide a suitable flexibility and lubricity. Example materials include high density polyethylene, 77A PEBAX, 33D PEBAX, 42D PEBAX, 46D PEBAX, 54D PEBAX, 69D PEBAX, 72D PEBAX, 90D PEBAX, and mixtures thereof or equivalent stiffness and lubricity material. In some implementations, the elongate body 360 is an unreinforced, non-torqueing catheter having a relatively large outer diameter designed to fill the lumen it is inserted through and a relatively small inner diameter to minimize any gaps at a distal-facing end of the device. In other implementations, at least a portion of the elongate body 360 can be reinforced to improve navigation and torqueing (e.g. braided reinforcement layer). The flexibility of the elongate body 360 can increase towards the distal end region 346 such that the distal region of the elongate body 360 is softer, more flexible, and articulates and bends more easily than a more proximal region. For example, a more proximal region of the elongate body can have a bending stiffness that is flexible enough to navigate tortuous anatomy, such as the carotid siphon, without kinking. If the elongate body 360 has a braid reinforcement layer along at least a portion of its length, the braid reinforcement layer can terminate a distance proximal to the distal end region 346. For example, the distance from the end of the braid to the distal-most end 325 can be about 10 cm to about 15 cm or from about 4 cm to about 10 cm or from about 4 cm up to about 15 cm.
In some implementations, the elongate body 360 can be generally tubular along at least a portion of its length such that it has a single lumen 368 extending parallel to a longitudinal axis of the catheter advancement element 300 (see
A guidewire 500 can extend through the single lumen 368 generally concentrically from a proximal opening to a distal opening 326 at the distal end 325 of the catheter advancement element 300 (see
The region near the distal end region 346 can be tapered such that the outer diameter tapers over a length of about 0.5 cm to about 5 cm, or 1 cm to about 4 cm, or other length as described elsewhere herein. The larger outer diameter can be at least about 1.5 times, 2 times, 2.5 times, or about 3 times larger than the smaller outer diameter. The distal end region 346 can taper along a distance from a first outer diameter to a second outer diameter, the first outer diameter being at least 1.5 times the second outer diameter. In some implementations, the distal end region 346 tapers from about 0.080″ (2.032 mm) to about 0.031″ (0.787 mm). In some implementations, the smaller outer diameter at a distal end of the taper can be about 0.026″ (0.66 mm) up to about 0.040″ (1.016 mm) and the larger outer diameter proximal to the taper is about 0.062″ (1.575 mm) up to about 0.080″ (2.032 mm). Also, the distal end region 346 can be formed of a material having a material hardness (e.g. 62A and 35D) that transitions proximally towards increasingly harder materials having (e.g. 55D and 72D) up to the proximal portion 366. A first segment of the elongate body 360 including the distal end region 346 can be formed of a material having a material hardness of 35D and a length of about 10 cm to about 12.5 cm. The first segment of the elongate body 360 including the distal end region 346 can be formed of a material having a material hardness of 62A and a length of about 10 cm to about 12.5 cm. A second segment of the elongate body 360 can be formed of a material having a material hardness of 55D and have a length of about 5 cm to about 8 cm. A third segment of the elongate body 360 can be formed of a material having a material hardness of 72D can be about 25 cm to about 35 cm in length. The three segments combined can form an insert length of the elongate body 360 from where the proximal portion 366 couples to the elongate body 360 to the terminus of the distal end region 346 that can be about 49 cm in length.
The catheter advancement element 300 can incorporate a reinforcement layer. The reinforcement layer can be a braid or other type of reinforcement to improve the torqueability of the catheter advancement element 300 and help to bridge the components of the catheter advancement element 300 having such differences in flexibility. The reinforcement layer can bridge the transition from the rigid, proximal portion 366 to the flexible elongate body 360. In some implementations, the reinforcement layer can be a braid positioned between inner and outer layers of PEBAX. The reinforcement layer can terminate a distance proximal to the distal end region 346. The distal end region 346 can be formed of a material having a material hardness of at most about 35D. The first segment can be unreinforced polymer having a length of about 4 cm up to about 12.5 cm without metal reinforcement. The third segment of the elongate body 360 located proximal to the first segment can include the reinforcement layer and can extend a total of about 37 cm up to the unreinforced distal segment. A proximal end region of the reinforcement layer can overlap with a distal end region of the proximal portion 366 such that a small overlap of hypotube and reinforcement exists near the transition between the proximal portion 366 and the elongate body 360.
The tubular portion of the catheter advancement element 300 can have an outer diameter that has at least one snug point. A difference between the outer diameter at the snug point and the inner diameter of the lumen at the distal end of the distal, catheter portion can be no more than about 0.015″ (0.381 mm), or can be no more than about 0.010″ (0.254 mm). The at least one snug point of this tubular portion can be a point along the length of the tubular portion. The at least one snug point of this tubular portion can have a length that is at least about 5 cm up to about 50 cm, including for example, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm up to about 50 cm. This length need not be uniform such that the length need not be snug along its entire length. For example, the snug point region can include ridges, grooves, slits, or other surface features.
In other implementations, the entire catheter advancement element 300 can be a tubular element configured to receive a guidewire 500 through both the proximal portion 366 as well as the elongate body 360. For example, the proximal portion 366 can be a tubular element having a lumen that communicates with the lumen 368 extending through the elongate body 360. In some implementations, the proximal portion 366 can be a skived hypotube of stainless steel coated with PTFE having an outer diameter of 0.026″ (0.660 mm). In other implementations, the outer diameter can be between 0.024″ (0.610 mm) and 0.030″ (0.762 mm). In some implementations, such as an over-the-wire version, the proximal portion 366 can be a skived hypotube coupled to a proximal hub or luer 364. The proximal portion 366 can extend eccentric or concentric to the distal luminal portion 222. The proximal portion 366 can be a stainless steel hypotube. The proximal portion 366 can be a solid metal wire that is round or oval cross-sectional shape. The proximal portion 366 can be a flattened ribbon of wire having a rectangular cross-sectional shape. The ribbon of wire can be curved into a circular, oval, c-shape, or quarter circle, or other cross-sectional shape along an arc. The proximal portion 366 can have any of variety of cross-sectional shapes whether or not a lumen extends therethrough, including a circular, oval, C-shaped, D-shape, or other shape. In some implementations, the proximal portion 366 is a hypotube having a D-shape such that an inner-facing side is flat and an outer-facing side is rounded. The rounded side of the proximal portion 366 can be shaped to engage with a correspondingly rounded inner surface of the sheath 400. The hypotube can have a lubricious coating, such as PTFE or other lubricious polymer covering the hypotube. The hypotube can have an inner diameter of about 0.021″ (0.533 mm), an outer diameter of about 0.0275″ (0.699 mm), and an overall length of about 94 cm providing a working length for the catheter advancement element 300 that is about 143 cm. Including the proximal luer 364, the catheter advancement element 300 can have an overall length of about 149 cm. In some implementations, the hypotube can be a tapered part with a length of about 100 mm, starting proximal with a thickness of 0.3 mm and ending with a thickness of 0.10 mm to 0.15 mm. In still further implementations, the elongate body 360 can be a solid element coupled to the proximal portion 366 having no guidewire lumen.
The proximal portion 366 is shown in
At least a portion of the solid elongate body 360, such as the elongate distal end region 346, can be formed of or embedded with or attached to a malleable material that skives down to a smaller dimension at a distal end. The distal end region 346 can be shaped to a desired angle or shape similar to how a guidewire may be used. The malleable length of the elongate body 360 can be at least about 1 cm, 3 cm, 5 cm, and up to about 10 cm, 15 cm, or longer. In some implementations, the malleable length can be about 1%, 2%, 5%, 10%, 20%, 25%, 50% or more of the total length of the elongate body 360. In some implementations, the catheter advancement element 300 can have a working length of about 140 cm to about 143 cm and the elongate body 360 can have an insert length of about 49 cm. The insert length can be the PEBAX portion of the elongate body 360 that is about 49.5 cm. As such, the malleable length of the elongate body 360 can be between about 0.5 cm to about 25 cm or more. The shape change can be a function of a user manually shaping the malleable length prior to insertion or the distal end region 346 can be pre-shaped at the time of manufacturing into a particular angle or curve. Alternatively, the shape change can be a reversible and actuatable shape change such that the distal end region 346 forms the shape upon activation by a user such that the distal end region 346 can be used in a straight format until a shape change is desired by the user. The catheter advancement element 300 can also include a forming mandrel extending through the lumen of the elongate body 360 such that a physician at the time of use can mold the distal end region 346 into a desired shape. As such, the moldable distal end region 346 can be incorporated onto an elongate body 360 that has a guidewire lumen.
The elongate body 360 can extend along the entire length of the catheter 200, including the distal luminal portion 222 and the proximal extension 230 or the elongate body 360 can incorporate the proximal portion 366 that aligns generally side-by-side with the proximal extension 230 of the catheter 200. The proximal portion 366 of the elongate body 360 can be positioned co-axial with or eccentric to the elongate body 360. The proximal portion 366 of the elongate body 360 can have a lumen extending through it. Alternatively, the portion 366 can be a solid rod or ribbon having no lumen.
Again with respect to
The catheter 200 and catheter advancement element 300 (with or without a guidewire) can be advanced as a single unit through both turns of the carotid siphon. Both turns can be traversed in a single smooth pass or throw to a target in a cerebral vessel without the step-wise adjustment of their relative extensions and without relying on the conventional step-wise advancement technique with conventional microcatheters. The catheter 200 having the catheter advancement element 300 extending through it allows a user to advance them in unison in the same relative position from the first bend of the siphon through the second bend beyond the terminal cavernous carotid artery into the ACA and MCA. Importantly, the advancement of the two components can be performed in a single smooth movement through both bends without any change of hand position.
The catheter advancement element 300 can be juxtapositioned relative to the catheter 200 that provides an optimum relative extension between the two components for single smooth advancement. The catheter advancement element 300 can be positioned through the lumen of the catheter 200 such that its distal end region 346 extends just beyond a distal-most end 215 of the catheter 200. The distal end region 346 of the catheter advancement element 300 eliminates the stepped transition between the inner member and the outer catheter 200 thereby avoiding issues with catching on branching vessels within the region of the vasculature such that the catheter 200 may easily traverse the multiple angulated turns of the carotid siphon. The optimum relative extension, for example, can be the distal end region 346 of the elongate body 360 extending just distal to a distal-most end 215 of the catheter 200. A length of the distal end region 346 extending distal to the distal-most end 215 of the catheter 200 during advancement can be between 0.5 cm and about 4 cm. This juxtaposition can be a locked engagement with a mechanical element or simply by a user holding the two components together. The mechanical locking element can be a fixed or removable mechanical element 605 configured to connect to one or more of the catheter 200, the catheter advancement element 300, and the guidewire 500. The mechanical locking element 605 can be slidable along at least a length of the system components when coupled so that the mechanical attachment is adjustable. The mechanical locking element 605 can be a disposable feature or reusable for connecting to at least a portion of the shaft or a more proximal portion of the component, such as the luer or hub at a proximal end of the component. In some implementations, the mechanical locking element 605 can be clamped onto the catheter 200 and the catheter advancement element 300 in a desired relative position so that the two can be advanced together without the relative position being inadvertently changed. The relative position can be changed, if desired, while the mechanical locking element 605 is clamped onto the catheter 200 and the catheter advancement element 300. The mechanical locking element 605 can be additionally clamped onto a region of the guidewire 500 extending through the catheter advancement element 300 such that the relative position of all three components can be maintained during advancement until a relative sliding motion is desired. In still further implementations, the clamping position of the mechanical locking element 605 can be changed from engaging with a first combination of components (e.g., the catheter, catheter advancement element, and the guidewire) to a different combination of components (e.g., the catheter advancement element and the guidewire) depending on what phase of the method is being performed. In still further implementations, the guidewire 500 is held fixed relative to the catheter advancement element 300 via a rotating hemostatic valve coupled to the proximal hub 434 and the catheter advancement element 300 is held fixed to the catheter 200 by a separate mechanical locking element 605. Whether the relative position of the components is fixed by a mechanical element, a combination of mechanical elements, or by a user, the proximal portions 264 of each of the catheter 200 and the catheter advancement element 300 (and the guidewire 500, if present) are configured to be held at a single point by a user. For example, where the catheter and catheter advancement element are advanced and/or withdrawn manually, the single point can be between just a forefinger and thumb of the user.
The components can be advanced together with a guidewire, over a guidewire pre-positioned, or without any guidewire at all. In some implementations, the guidewire can be pre-assembled with the catheter advancement element 300 and catheter 200 such that the guidewire extends through a lumen of the catheter advancement element 300, which is loaded through a lumen of the catheter 200, all prior to insertion into the patient. The pre-assembled components can be simultaneously inserted into the sheath 400 and advanced together up through and past the turns of the carotid siphon. A guidewire may be located within the lumen 368 of the catheter advancement element 300 and parked proximal of the tapered distal end region 346 or proximal of the distal tip for potential use in the event the catheter advancement element without a guidewire does not reach the target location. For example, a distal tip of the guidewire 500 can be positioned about 5 cm to about 40 cm, or about 20 cm to about 30 cm proximal of the distal end region 346 of the catheter advancement element 300. At this location the guidewire does not interfere with the performance or function of the catheter advancement element. The guidewire can be positioned within the lumen of the catheter advancement element such that the distal end of the guidewire is within the catheter advancement element during the step of advancing the assembled system of devices together and is extendable from the catheter advancement element out the distal opening 326 when needed for navigation. In one example, a rescue guidewire is parked within the lumen of the catheter advancement element with a distal end of the guidewire about 0 cm to about 40 cm proximal or about 5 cm to about 35 cm proximal or about 7 cm to about 30 cm of the distal end of the catheter advancement element, preferably about 10 cm proximal of the distal end of the catheter advancement element. The guidewire at this parked position can provide additional support for the proximal portion of the system without affecting the flexibility and performance of the distal portion of the system.
Standard neurovascular intervention, and nearly all endovascular intervention, is predicated on the concept that a guidewire leads a catheter to a target location. The guidewires are typically pre-shaped and often find side-branches of off-target locations where the guidewire will bunch or prolapse causing time-consuming nuisances during interventions that often require repeated redirection of the guidewire by the operator to overcome. In addition, this propensity of a guidewire to enter side-branches can be dangerous. Guidewires are typically 0.014″ to 0.018″ (0.356 mm-0.457 mm) in the neuroanatomy and will find and often traumatize dissection flaps or small branches that accommodate this size, which can lead to small bleeds or dissections and further occlusion. In a sensitive area like the brain these events can be catastrophic. The tendency of a guidewire to bunch and prolapse can also cause a leading edge to the guidewire that can be advanced on its own or as part of a tri-axial system to create dissection planes and traumatize small vessels.
In contrast, the catheter advancement element 300 described herein preferentially stays in the larger lumen of a conduit vessel. The catheter advancement element 300 delivers to the largest lumen within the anatomy even in light of the highly tortuous anatomy and curves being navigated. The catheter advancement element 300 can preferentially take the larger lumen at a bifurcation or dissection flap while also following the current of the greatest blood flow thereby maintaining the general direction and angulations of the parent vessel. In viewing the standard anatomy found in the cerebral vasculature, the Circle of Willis is fed by two vertebral and two carotid conduit arteries. As these four arteries are the access points to the cerebral anatomy—the course of the catheter advancement element 300 can be identified and has been validated in standard cerebral anatomy models.
In the anterior circulation where the conduit artery point of entry for cerebral endovascular procedures is the internal carotid artery (ICA), the catheter advancement element can guide the large-bore catheter to the M1 segment of the middle cerebral artery (MCA) bypassing the anterior communicating artery (ACA) and anterior temporal branch (ATB). The very flexible nature of the catheter advancement element 300 combined with the distal flexible nature of most cerebral catheters combine to allow delivery through severe tortuosity. Independent of the tortuous nature of the course of the arteries, the catheter advancement element 300 tends to navigate the turns and deliver to the largest offspring from a parent artery, for example, ICA to M1 segment of the MCA. The M2 level branching of the M1 can be variable, but is often seen to have two major M2 branches (superior and inferior) and, depending on the anatomy, which can vary significantly between patients, may be seen to bifurcate “equally” or “unequally.” If the caliber of the M2 branching is of similar size and angulation, the catheter advancement element 300 may take one of the two branches. If the target for catheter placement is not in a favorable angulation or size of artery, the catheter advancement element 300 may be curved (e.g., via shaping of a malleable distal tip) and directed or a guidewire may be used.
In some anatomies where the M2 bifurcation is “even” in size, a back-and-forth motion may aid in selecting one branch then the other while still avoid the need or use of a guidewire or a curved distal tip of the catheter advancement element. The back-and-forth motion can allow for the catheter advancement element to be directed into either branch of the M2. The catheter advancement element, even when initially straight, achieves some curvature that aids in directing it into a branch vessel. Thus, when an operator encounters an M2 bifurcation and there is a desire to cannulate either branch of an evenly divided bifurcation, selection of either branch is possible using the catheter advancement element without a guidewire.
Thus, main channels, such as the ICA, the middle cerebral artery and its tributaries in the anterior circulation will naturally be the pathway of preference for the described catheter advancement element and subsequence large-bore catheter delivery (via access from the ICA). A similar phenomenon can occur in the posterior circulation, which is accessed via the vertebral arteries arising from the subclavian arteries on the right and the left. The catheter advancement element will take the main channels in this circulation as well by traversing the vertebral arteries to the basilar artery and to the major tributaries of the basilar: the posterior cerebral artery and superior cerebellar arteries in the posterior circulation.
Navigation using the catheter advancement element can provide maximal deliverability with minimal vascular trauma. Catheters can cause “razoring” effects in a curved vessel because the blunt end of a large bore catheter can tend to take the greater curve in rounding a vessel when pushed by the operator. This blunt end can gouge or “razor” the greater curve with its sharp edge increasing the risk for dissection along an anatomic plane within the multilayered mid- or large-sized artery or vein (see, e.g., Catheter Cardiovasc. Interv. 2014 February; 83(2):211-20). The catheter advancement element can serve to minimize the edge of these catheters. Positioning the catheter advancement element within the lumen of the large-bore catheter such that the taper marker of the catheter advancement element is aligned optimally with the distal tip marker of the catheter minimizes the edge and thereby eliminates “razoring” as the large-bore catheter is advanced through turns of the vessel. This is particularly useful for the cerebral anatomy. Treatments distal to the carotid siphon, particularly distal to the ophthalmic artery takeoff from the greater curve of the severe tortuosity of the final turn of the carotid siphon “S-turn”, the “anterior genu” of the carotid siphon typically seen as part of the terminal internal carotid artery (ICA) can be improved using the access system described herein. The specifics of the catheter advancement element in proper alignment within the large bore catheter (the “tip-to-taper” position noted by the distal tip marker) relative to the taper marker of the catheter advancement element maximize the likelihood that razoring and hang-up on the ophthalmic artery are avoided during manual advancement of the catheter system. The taper marker of the catheter advancement element can be positioned at or past the take-off of the ophthalmic artery to minimize these deleterious effects and allows the large-bore catheter to pass the ophthalmic artery without incident. In a relatively straight segment, which is common after passing the siphon, the large-bore catheter can be advanced over the catheter advancement element, which serves still as a guiding element to the target. The transition between the catheter advancement element and the distal edge of the large-bore catheter is insignificant, especially compared to the step changes present with a typical microcatheter or guidewire, which do not prevent hang-ups on branches, such as the ophthalmic artery. The catheter advancement element allows for maneuvering of the large-bore catheter to distal sites without use of a microcatheter or guidewire.
The systems described herein can but need not incorporate a guidewire. And, if a guidewire is used, it need not be advanced independently (i.e., unsheathed) to the target treatment site. Thus, the systems described herein can incorporate relatively large bore catheters that are delivered without disturbing anatomy with a guidewire, reducing the risk for stroke and downstream effects from fragmentation of an occlusion, and having improved efficiency. Additionally, the systems described herein are single-operator systems allowing the operator to work at a single RHV and, in the case of spined components, can manipulate all the elements being used to navigate the anatomy with single-handed “pinches.” This can be referred to as “monopoint.”
Any flow diverter described herein may be used with any device delivery system including but not limited to those described here, and may be delivered via access catheters including but not limited to those described here.
The access catheter systems, flow diverters and delivery systems described herein can be used to access and treat intracranial and cerebral aneurysms. The access catheter systems provide monopoint manipulation at the base sheath for the various tools used in the method providing improved safety, ease of use, and single operator manipulations compared to conventional systems. These catheter systems provide easy and quick access to target sites even through tortuous anatomy to reach the target lesion. The flow diverters and delivery systems described herein provide improved, more accurate, and safer treatment of aneurysms. In addition, the flow diverters described here have potentially reduced complication rates due to the geometry of the device apposition against the wall.
A method for the treatment of cerebral or intracranial aneurysm is now described. The method can include a flow diverter and flow diverter delivery system advanced over a guidewire (or not) through an outer catheter extending through a base sheath. The catheter can be a conventional full-length catheter, but is preferably a catheter having a larger diameter distal luminal portion 222 coupled to a smaller diameter proximal control element 230 as shown in
The distal end region of the outer catheter 200 can be advanced over the inner catheter 300 and positioned across the aneurysm A. The inner catheter 300 can be withdrawn from the outer catheter 200 and the outer catheter 200 maintained in position across the aneurysm (see
The flow diverter delivery system 800 can include an inner core member 820 and an outer restraining sleeve 810. The flow diverter 700 can be mounted on the inner core member 820 and constrained by the outer restraining sleeve 810 during delivery. The flow diverter 700 constrained by the outer restraining sleeve 810 can be deliverable through a delivery catheter having an inner diameter that is between 2.0 mm and 3.0 mm. Deployment of the flow diverter 700 across the aneurysm A can be achieved, for example, in reference to
The flow diverter 700 can be any of those described previously. For example. The flow diverter can be a laser-cut expandable metal tube. The flow diverter can be formed of first and second expandable tubes where each is a laser cut metal tube. The first expandable tube can be a laser cut metal tube and the second expandable tube can be a braided tube. Alternatively, the first expandable tube can be a laser cut metal tube and the second expandable tube can be a polymer sleeve. The flow diverter can have a compound construction. The compound construction can include two end sections constructed from laser-cut tube and a middle section that is a braid.
One or more components of the catheters, delivery systems, and flow diverters described herein may include or be made from a variety of materials including one or more of a metal, metal alloy, polymer, a metal-polymer composite, ceramics, hydrophilic polymers, polyacrylamide, polyethers, polyamides, polyethylenes, polyurethanes, copolymers thereof, polyvinyl chloride (PVC), PEO, PEO-impregnated polyurethanes, such as Hydrothane, Tecophilic polyurethane, Tecothane, PEO soft segmented polyurethane blended with Tecoflex, thermoplastic starch, PVP, and combinations thereof, and the like, or other suitable materials.
Some examples of suitable cut-tube or flat metal material includes Nitinol, Layered tube with Nitinol on outside and inner core of radiopaque material, such as tantalum, platinum, iridium, gold, alloy etc. Additionally, material could be cobolt, cobolt alloy, or stainless steel.
Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy, such as linear-elastic and/or super-elastic Nitinol; other nickel alloys, such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625, such as INCONEL® 625, UNS: N06022, such as HASTELLOY® C-22®, UNS: N10276, such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400, such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035, such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665, such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003, such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material and as described elsewhere herein.
Inner liner materials of the catheters described herein can include low friction polymers, such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene), PTFE with polyurethane layer (Tecoflex). Reinforcement layer materials of the catheters described herein can be incorporated to provide mechanical integrity for applying torque and/or to prevent flattening or kinking, such as metals including stainless steel, Nitinol, Nitinol braid, helical ribbon, helical wire, cut stainless steel, or the like, or stiff polymers, such as PEEK. Reinforcement fiber materials of the catheters described herein can include various high tenacity polymers like Kevlar, polyester, meta-para-aramide, PEEK, single fiber, multi-fiber bundles, high tensile strength polymers, metals, or alloys, and the like. Outer jacket materials of the catheters described herein can provide mechanical integrity and can be contracted of a variety of materials, such as polyethylene, polyurethane, PEBAX, nylon, Tecothane, and the like. Other coating materials of the catheters described herein include paralene, Teflon, silicone, polyimide-polytetrafluoroetheylene, and the like. The inner liner may further include different surface finishes, such as dimples, bumps, ridges, troughs. The surface finishes may be randomly disposed, linearly disposed, spirally disposed, or otherwise disposed using a specific pattern along the length of the catheter. It is further contemplated that the inner liner may include a mixture of different surface finishes, for example, one section may have dimples, another section may have troughs, etc. Additionally, the surface finish may be incorporated along the entire length of the catheter or only in sections of the catheter. It is also contemplated that the inner liner may further include an electrosprayed layer, whereby materials could be incorporated into the inner liner. Examples of materials can include low friction materials as described above. Alternatively, the electrosprayed or electrospun layer may incorporate a beneficial agent that becomes free from the coating when exposed to blood, or to compression from a clot, for example, the beneficial agent may be a tissue plasminogen activator (tPA) or heparin encased in alginate.
Implementations describe catheters and delivery systems and methods to deliver catheters to target anatomies. However, while some implementations are described with specific regard to delivering catheters to a target vessel of a neurovascular anatomy, such as a cerebral vessel, the implementations are not so limited and certain implementations may also be applicable to other uses. For example, the catheters can be adapted for delivery to different neuroanatomies, such as subclavian, vertebral, carotid vessels as well as to the coronary anatomy or peripheral vascular anatomy, to name only a few possible applications. It should also be appreciated that although the systems described herein are described as being useful for treating a particular condition or pathology, that the condition or pathology being treated may vary and are not intended to be limiting.
In various implementations, description is made with reference to the figures. However, certain implementations may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the implementations. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one embodiment,” “an embodiment,” “one implementation, “an implementation,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment or implementation. Thus, the appearance of the phrase “one embodiment,” “an embodiment,” “one implementation, “an implementation,” or the like, in various places throughout this specification are not necessarily referring to the same embodiment or implementation. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more implementations.
The use of relative terms throughout the description may denote a relative position or direction. For example, “distal” may indicate a first direction away from a reference point. Similarly, “proximal” may indicate a location in a second direction opposite to the first direction. The reference point used herein may be the operator such that the terms “proximal” and “distal” are in reference to an operator using the device. A region of the device that is closer to an operator may be described herein as “proximal” and a region of the device that is further away from an operator may be described herein as “distal”. Similarly, the terms “proximal” and “distal” may also be used herein to refer to anatomical locations of a patient from the perspective of an operator or from the perspective of an entry point or along a path of insertion from the entry point of the system. As such, a location that is proximal may mean a location in the patient that is closer to an entry point of the device along a path of insertion towards a target and a location that is distal may mean a location in a patient that is further away from an entry point of the device along a path of insertion towards the target location. However, such terms are provided to establish relative frames of reference, and are not intended to limit the use or orientation of the catheters and/or delivery systems to a specific configuration described in the various implementations.
The word “about” means a range of values including the specified value, which a person of ordinary skill in the art would consider reasonably similar to the specified value. In embodiments, about means within a standard deviation using measurements generally acceptable in the art. In embodiments, about means a range extending to +/−10% of the specified value. In embodiments, about includes the specified value.
While this specification contains many specifics, these should not be construed as limitations on the scope of what is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Only a few examples and implementations are disclosed. Variations, modifications and enhancements to the described examples and implementations and other implementations may be made based on what is disclosed.
In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.”
Use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.
The components of the systems disclosed herein may be packaged together in a single package or separately. The finished package would be sterilized using sterilization methods such as Ethylene oxide or radiation and labeled and boxed. Instructions for use may also be provided in-box or through an internet link printed on the label.
This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial Nos. 63/338,114, filed May 4, 2022, 63/346,524, filed May 27, 2022, and 63/422,762, filed Nov. 4, 2022. The disclosures are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 63422762 | Nov 2022 | US | |
| 63346524 | May 2022 | US | |
| 63338114 | May 2022 | US |
