Tubular support body of catheter

Abstract

To provide an improved recovery catheter.SOLUTION: A thrombus recovery catheter includes: a body having an adjusted high flexibility and which can advance along a meandered path; and a tip end part which can be expanded for locally restricting / stopping the flow. The body may be a support pipe composed of a strut having a plurality of ribs and one or more axial spine. The support pipe may be a tubular part having a radial slot pattern for inhibiting a kink and coupling while enhancing the flexibility. The rib and spine may include a strut width that changes along a length of the support pipe, or may include a curved part with a non-planar cross section. The rib can be formed to be movable when a load of a thrombus removal operation is applied. The support pipe may be configured in a braided strand or woven-cloth pattern. The support pipe may include a polymer jacket or a membrane provided at least a part of a periphery of the structure.SELECTED DRAWING: Figure 20b

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to devices and methods for removing acute occlusions from blood vessels during intravascular medical procedures, and more particularly, to retrieval aspiration catheters. [Background technology]

[0002] Aspiration and thrombectomy catheters and devices are often used for mechanical thrombectomy to perform endovascular interventions, such as in patients with conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). With conventional techniques, access to the neurovascular bed, in particular, has been difficult because the target vessels are small in diameter, far from the insertion site, and highly tortuous.

[0003] To deliver an effective device to the small, highly branched cerebral arterial system, conventional catheters must balance many factors. A catheter must be flexible enough to track through the vasculature and withstand large bending strains, while also possessing axial stiffness to provide smooth, stable advancement along the path. New designs have been introduced that utilize various methods to vary stiffness between the proximal and distal sections of the catheter. However, abrupt changes in stiffness or shape can impair compliance, introduce large stress concentrations, and potentially increase the likelihood of device kinking or buckling.

[0004] When aspiration is performed with a conventional fixed-port catheter, i.e., an outer catheter and an unsealed catheter, a significant portion of the aspiration flow is drawn from the vascular fluid near the tip of the catheter, where no thrombus is present. This significantly reduces aspiration efficiency and reduces the success rate of thrombus removal. For example, a hard, fibrin-rich thrombus can become lodged in the tip of a conventional fixed-port catheter, making it often difficult to extract. This lodging can cause the soft portion of the thrombus to break away from the hard area.

[0005] Other aspiration catheter designs feature large-diameter, distally facing ports for maximum efficiency. For example, the ports may be designed with diameters significantly larger than typical delivery catheters or sheaths. As a result, the ports must not only be flexible and low-profile for delivery within an outer catheter, but also be capable of being deployed to the target site and expanding to an enlarged configuration at the target site. The catheter's support tube must have sufficient flexibility for access while possessing characteristics that allow it to effectively transfer thrust loads to the port at the distal tip.

[0006] However, many flexible body designs have small diameters that cannot generate the required suction force, while designs with expandable members or separate suction extensions may lack the flexibility to navigate intact through the neurovasculature. Not only must the catheter elements be able to withstand the large mechanical strains they are subjected to, but they must also generate sufficient radial force upon expansion to prevent the catheter and vessel from collapsing under the suction pull. Summary of the Invention [Problem to be solved by the invention]

[0007] The present design aims to provide an improved retrieval catheter with an expandable tip that incorporates these features to overcome the above-mentioned drawbacks. [Means for solving the problem]

[0008] The design herein can be for a thrombectomy catheter that can have an adjustable main support tube section with sufficient flexibility to navigate highly tortuous regions of anatomy, such as neurovasculature, to reach an occlusive thrombus. The support tube can be formed with or have attached to it an expandable catheter tip with a large opening facing the thrombus that can locally restrict / stop flow within the target vessel. The catheter can also be compatible with relatively low-profile access sheaths and catheters for additional deliverability benefits.

[0009] The thrombectomy catheter can have a generally tubular body with a supporting framework defining a longitudinal axis. The large-diameter catheter lumen can be configured to pass guidewires, microcatheters, stent retrieval devices, and other such devices. The lumen can also direct aspiration to the catheter tip. The tubular body can extend from a proximal end and terminate at a distal end, where an expandable tip can be integrally formed or fixedly connected. The tip can be configured to expand from a collapsed delivery configuration to an expanded, deployed configuration upon deployment at the site of an occlusive thrombus.

[0010] The supporting framework structure can have one or more axial spines extending longitudinally from the proximal end to the distal end. A series of loop ribs can be disposed along at least the length of one or more longitudinal spines. Each rib of the supporting framework structure can define an internal lumen of the catheter extending through the catheter. Each rib can intersect with one or more spines at a junction point. The junction point can have a strain relief notch feature or similar shape to relieve stress at the rib-spine junction as the catheter navigates through tortuous vessels within the vasculature. Optionally, instead of having separate junction points, multiple ribs can be integrated into a spine connector to minimize connections with the spine, thereby improving the flexibility of the support tube. The ribs can have curved or tapered winged portions that merge into a spine connector with a single junction point with each rib.

[0011] The ribs and spine can be monolithically formed by laser machining of hypotubes or extrusion of polymer tubing. In another embodiment, the tubular body can be a metallic braided or coiled wire structure. The spine can be fixedly connected to or integrally formed with a portion of the expandable tip.

[0012] At least a portion of the tubular portion can seal or form a flow restriction with the outer catheter so that suction is directed to the distal tip of the thrombectomy catheter. A polymer cover or membrane can be disposed around the supporting framework and at least a portion of the tip to enclose the catheter body. In another example, the cover can be a series of polymer jackets with varying stiffness and flexure characteristics. The cover can be reflowed, glued, and / or sewn to the framework of the supporting structure. The cover can be further coated with a low-friction layer or film to improve compliance and reduce the risk of binding or excessive friction when delivered through the outer catheter.

[0013] The trackability and flexibility of the catheter within the vasculature can be adjusted by adjusting the properties of the support tube. For example, the bending plane of the support tube can be defined by the location of the axial spine when the spine or spines are straight, parallel members. In another embodiment, the spine or spines can be arranged in a spiral or helical pattern around the longitudinal axis of the support tube. The spine or spines can have a different width in a more proximal portion of the support tube than in a more distal portion. The transition from one spine width to another can be a continuous taper, or it can transition between axial portions of increasingly flexible framework structures.

[0014] The struts forming the ribs of the support tube framework can have varying widths, with a first rib width on one rib being different from a second rib width on another rib. The ribs can also be in a helical pattern, with rib-to-spine junctions staggered by a coiled structure. The spacing, or pitch, between adjacent ribs can vary between the proximal and distal ends of the support framework, allowing one segment of the framework to have a denser rib pattern with greater stiffness than another segment with greater rib spacing.

[0015] In another embodiment, the ribs can be cut or formed to be disposed at a non-perpendicular angle relative to the longitudinal axis of the support framework, thereby allowing the diameter of the internal lumen to change as the ribs move in response to tension or compression forces on the support tube during a thrombectomy procedure. The ribs can be formed so that they have a non-planar cross-section and the cross-sectional shape of the rib struts has one or more proximal and / or distal curves or undulations. The ribs can also be configured to move relative to their respective junctions with one or more spines, allowing the support tube to locally expand to pass hard or incompressible trapped thrombus.

[0016] In another embodiment, a support tube for forming the body of a catheter assembly can have a tubular support framework structure having a proximal end, a distal end, an interior lumen, and a pattern of radial slots configured about a longitudinal axis. The radial slots can be cut, for example, into the circumference of a through-extruded polymer tube at different clock positions, so that the radial slots are discontinuous and do not run completely around the circumference. The cuts can form slots of constant or variable length. By aligning the cut segments, the slots in the support tube can define intermittent spines, continuous spines, or both intermittent and continuous spines that extend the length of the tube.

[0017] In one embodiment, adjacent interrupted radial slots offset 90° from one another can form two interrupted spines. When offset in this manner, the two interrupted spines can define two bending planes that are perpendicular to one another and aligned perpendicularly through the longitudinal axis of the supporting framework. Additional spines and bending planes can be formed by interrupting the cuts at additional locations along the circumference of the tube and axially aligning or offsetting adjacent cuts as desired.

[0018] In other cases, the radial slots can be cut in a helical pattern, with the cuts in adjacent turns aligned to form one or more continuous and / or discontinuous spines. In one embodiment, the helical pattern of intermittent slots can include at least two cuts per turn. In another embodiment, the helical pattern can include more than two cuts per turn to form both continuous and discontinuous spines that are circumferentially offset from one another. Multiple cuts per turn can provide flexibility along multiple different planes.

[0019] The radial slots in the support tube may extend nearly or completely around the longitudinal axis. In this configuration, the slots divide the axial length of the support tube into a series of rings between the proximal and distal ends of the tube. The rings may be of a constant length or may vary in length. Individual rings may be connected to adjacent rings via a series of linkages along the circumference of each ring. The distal linkages may interlock a particular ring with the next distal ring, and the proximal linkages may interlock with the next proximal ring. The overall flexibility of the tube may be varied by varying the number of linkages or their shape or circumferential spacing. The linkages allow the support tube to transfer axial and torsional loads, minimizing tube expansion under tension without the use of spines. Alternatively, one or more spines may be formed in the support tube by interrupting the slots at multiple points along the circumference and then aligning or offsetting the interruptions to form continuous or discontinuous spines.

[0020] In another embodiment, the support tube of the catheter body can have a generally cylindrical braid pattern formed by a plurality of strands centered about the longitudinal axis. The cylindrical braid of the strands can define the lumen of the support tube. One or more spines can extend longitudinally along the braid pattern between its proximal and distal ends, and a polymer cover can be disposed around at least a portion of the braid pattern. The polymer cover can encapsulate at least a portion of the braid pattern and fill gaps in the braid.

[0021] At least one of the one or more spines can be interwoven with the strands of the braid pattern. A design with spines woven into the braid can limit the structure's ability to elongate under tension or shorten under compression. The spines can have widths that vary between the proximal and distal ends of the braid pattern to improve bending flexibility.

[0022] In a braided pattern, an angle is formed where two strands meet within the fabric. The angle formed by the strands can be used to tailor mechanical properties, and different angles can be used in different axial segments of the support tube. In one case, the angle of the braided pattern ranges from about 20 to 90 degrees.

[0023] A method for constructing a thrombectomy catheter is also provided. The method can include the step of defining a tubular support of the catheter by disposing a plurality of ribs along its length. The ribs can be circular or some other shape and can be disposed at a predetermined orientation about the longitudinal axis of the tubular support. The ribs can also be oriented at an angle other than perpendicular to the axis, thereby allowing the ribs to move when subjected to the forces of a thrombectomy procedure. As a thrombus is drawn into the distal port of the catheter, a compressive force can be transmitted to the ribs, causing at least a portion of the rib to move proximally relative to the longitudinal axis, effectively increasing the local diameter of the inner lumen of the catheter.

[0024] One or more axial spines can be formed along the length of the tubular support, and multiple ribs can be connected at junctions to transmit thrust through the tubular support. In one embodiment, one or more spines can be integrally formed with the ribs of the support, such as a laser-cut hypotube. The one or more spines can be straight and parallel to the longitudinal axis, or they can be formed in a spiral or helix about the axis. A radially expandable tip can be connected to the distal end of the tubular support or integrally formed with the distal end of the tubular support. A further step can include disposing a polymer cover around the tubular support and at least a portion of the expandable tip. The cover can be elastic so that it stretches as the tip expands, or it can be pouch-like or loosely sized around the scaffold so that the entire radial force of the tip is transmitted to the vessel wall.

[0025] Another step can include forming and arranging ribs and spines to tailor the bending stiffness of the catheter tubular support at different portions along its length. The ribs can be more closely spaced or have a thicker strut width at the proximal end, for example. Similarly, one or more spines can have increasing widths proximally and taper distally to a narrower profile to provide good pushability and greater distal flexibility required for access.

[0026] Bending stiffness can be adjusted by either or a combination of varying the cut width and / or the rib width. If the cut width is kept constant, bending stiffness can be adjusted by, for example, varying the width of the laser beam, the rib width, and / or the width of the spine(s). If the cut width is varied, the rib width may be kept constant or varied, and the laser can be used to remove material. It will be appreciated that by using a cut width equal to the cut width of the laser beam, no material is removed, significantly reducing manufacturing costs. In contrast, using a laser to remove material allows for greater variation in shaft design. It will also be appreciated that a combination of both approaches can be used, such that the shaft incorporates more cost-effective cutting / machining means at the proximal end, while more expensive approaches are maintained at a specific distance at the distal end where more complex cutting may be required to achieve desired performance. For example, the distal end can include a 20 cm long section with cuts that remove material and also include an expandable tip cut. In another embodiment, the proximal section of the shaft can be cut from SS and joined with a distal section cut from NiTi, reducing overall cost while providing the benefits of NiTi at the distal end of devices requiring increased resilience in tight bends and additional expansion and recovery characteristics. In such devices, the SS and NiTi sections can be joined by direct welding or by welding to a more suitable intermediate metal, such as platinum. Alternatively, a laser-cut interlocking mechanism can hold both cut tubes together longitudinally. An outer membrane cover or jacket can hold the tubes together radially.

[0027] Other aspects and features of the present disclosure will become apparent to those skilled in the art from the following detailed description considered in conjunction with the accompanying figures. [Brief explanation of the drawings]

[0028] These and further aspects of the present invention will be further considered with reference to the following description taken in conjunction with the accompanying drawings, in which: The drawings are not necessarily to scale, but instead focus on illustrating the principles of the invention. The figures depict one or more implementations of the apparatus of the present invention, by way of example only, and not by way of limitation. [Figure 1] FIG. 1 is an isometric view of a thrombectomy catheter having a tubular support and an expandable distal tip, according to an aspect of the present invention. [Figure 2] 1 shows an isometric view of a tubular support having a circular rib and two axial spines according to an embodiment of the present invention. [Figure 3a] 1 is a series of views of a support tube according to an embodiment of the present invention. [Figure 3b] 1 is a series of views of a support tube according to an embodiment of the present invention. [Figure 3c] 1 is a series of views of a support tube according to an embodiment of the present invention. [Figure 3d] 1A-1C are a series of views of a support tube according to an embodiment of the present invention. [Figure 4a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 4b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 4c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 4d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 5a] 10 is another support tube having spiral ribs according to an embodiment of the present invention. [Figure 5b] 10 is another support tube having a variable rib pitch, according to an aspect of the present invention. [Figure 6a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 6b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 6c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 6d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 7a]10A-10C are a series of views of another support tube having a helical spine, according to an embodiment of the present invention. [Figure 7b] 10A-10C are a series of views of another support tube having a helical spine, according to an embodiment of the present invention. [Figure 7c] 10A-10C are a series of views of another support tube having a helical spine, according to an embodiment of the present invention. [Figure 7d] 10A-10C are a series of views of another support tube having a helical spine, according to an embodiment of the present invention. [Figure 8a] 10A-10C are a series of views of another support tube having two helical spines, according to an embodiment of the present invention; [Figure 8b] 10A-10C are a series of views of another support tube having two helical spines, according to an embodiment of the present invention; [Figure 8c] 10A-10C are a series of views of another support tube having two helical spines, according to an embodiment of the present invention; [Figure 8d] 10A-10C are a series of views of another support tube having two helical spines, according to an embodiment of the present invention; [Figure 8e] 1 is a depiction of a strain relief notch in a support tube according to an aspect of the present invention. [Figure 9a] 10A-10C are a series of views of another support tube having radial slots in accordance with an aspect of the present invention; [Figure 9b] 10A-10C are a series of views of another support tube having radial slots in accordance with an aspect of the present invention; [Figure 9c] 10A-10C are a series of views of another support tube having radial slots in accordance with an aspect of the present invention; [Figure 9d] 10A-10C are a series of views of another support tube having radial slots in accordance with an aspect of the present invention; [Figure 9e] 10 is a depiction of the cut per revolution of a radial slot in a support tube according to an embodiment of the present invention. [Figure 10a] 10A-10C are two views of another support tube having radial T-slots for strain relief, according to an embodiment of the present invention. [Figure 10b] 10A-10C are two views of another support tube having radial T-slots for strain relief, according to an embodiment of the present invention. [Figure 11a]1 is a flat pattern of an exemplary support tube with T-slots and profiled ribs according to an embodiment of the present invention. [Figure 11b] 10 is a flat pattern of another exemplary support tube having T-slots and profiled ribs, according to an embodiment of the present invention. [Figure 12a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 12b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 12c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 12d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 13a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 13b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 13c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 13d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 14] 13b is an enlarged distal tip of the catheter connected to the support tube of FIG. 13a, according to an embodiment of the present invention. [Figure 15a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 15b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 15c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 15d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 16] 15b is an enlarged distal tip of the catheter connected to the support tube of FIG. 15a, according to an embodiment of the present invention. [Figure 17a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 17b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 17c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 17d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 18a] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 18b] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 18c] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 18d] 10A-10C are a series of views of another support tube according to an aspect of the present invention. [Figure 19a] 10A-10C illustrate various possible strain relief notches according to aspects of the present invention. [Figure 19b] 10A-10C illustrate various possible strain relief notches according to aspects of the present invention. [Figure 19c] 10A-10C illustrate various possible strain relief notches according to aspects of the present invention. [Figure 20a] 1 is a support tube having multiple ribs sharing a spine connection, according to an aspect of the present invention. [Figure 20b] 10 is an alternative support tube having multiple ribs sharing a spine connection, according to an aspect of the present invention. [Figure 20c] 10 is another support tube having multiple ribs sharing spine connections with multiple spines, according to an aspect of the present invention. [Figure 21a] 1 is a puzzle cut support tube having rings connected by a linking mechanism according to an aspect of the present invention. [Figure 21b] FIG. 21b is a close-up view of the support tube arrangement of FIG. 21a, according to an embodiment of the present invention. [Figure 21c] 10 is another puzzle cut support tube having a linkage mechanism and rings connected by a single spine, according to an aspect of the present invention. [Figure 21d] FIG. 21c is a close-up view of the support tube arrangement of FIG. 21c, according to an embodiment of the present invention. [Figure 21e] 10 is another puzzle-cut support tube having a linkage mechanism and a ring connected by two spines, according to an embodiment of the present invention. [Figure 21f] FIG. 21c is a close-up view of the support tube arrangement of FIG. 21e, according to an embodiment of the present invention. [Figure 22a] 1 is a diagram of a braided support tube according to an embodiment of the present invention. [Figure 22b] 1 is a diagram of a braided support tube according to an embodiment of the present invention. [Figure 23] FIG. 1 is a flow diagram outlining a method for using a system in accordance with an aspect of the present invention. [Figure 24] FIG. 1 is a flow diagram outlining a method for using a system in accordance with an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The objective of the disclosed design is to create a thrombectomy catheter with a radially expandable distal tip for localized blood flow restriction / stoppage and a tailored, highly flexible body section capable of navigating tortuous regions of the vasculature to reach occlusive thrombi. This advantage may also be particularly beneficial in stroke interventional procedures, where the vessels in the neurovascular bed are small and highly tortuous, and carefully designed axial and bending stiffness profiles can prevent kinking and binding. The catheter is also compatible with relatively low-profile access sheaths and catheters, allowing for easy and reliable closure of a puncture wound in the patient's groin (in the case of femoral access). The support structure may also include internal and / or external low-friction liners, as well as an outer polymer jacket or membrane disposed around the support structure.

[0030] An advantage of using an expandable-port thrombectomy catheter with an outer catheter is that, if both catheters are flexible enough to reach the target, the thrombectomy catheter can be retracted through the outer catheter, along with the thrombus, leaving the outer catheter in place to maintain access to the treatment site. While it is recognized that certain thrombi may require the outer catheter to be retracted along with the thrombus and inner thrombectomy catheter, the majority of the thrombus is likely to be removed through the inner thrombectomy catheter. Furthermore, because the lumen of the outer catheter is more likely to be free of debris, there is less risk during contrast injection that potential thrombus residue will become dislodged from the catheter during contrast injection, as occurs when using standard mid-catheters. To address this dislodgment, the user can remove the mid-catheter and flush any thrombus residue outside the body before contrast injection, at the cost of losing access to the target treatment site. In contrast, the present design provides an additional means for minimizing the number of catheter advancements required to treat a patient, thereby reducing the potential for vessel injury and the associated risk of vessel transection if multiple passes are required.

[0031] Although these descriptions are often in the context of mechanical thrombectomy therapy, the systems and methods may be adapted for other procedures and other body passageways as well.

[0032] Specific embodiments of the present invention will now be described in detail with reference to the drawings, wherein like reference numerals indicate functionally similar or identical elements. Accessing various blood vessels within the vascular system, whether coronary, pulmonary, or cerebral, involves well-known procedural steps and the use of many conventional, commercially available accessory products. These products, such as angiographic materials, rotating hemostatic valves, and guidewires, are widely used in laboratories and medical procedures. When these or similar products are used in conjunction with the systems and methods of the present invention in the following description, their function and exact configuration will not be described in detail.

[0033] 1 shows a thrombectomy catheter 35 for use in retrieving thrombus or occlusion material from a patient's blood vessel. The thrombectomy catheter 35 can include an elongate proximal catheter shaft 30, or guidewire, for steering and delivering the catheter, a support tube 100 forming the catheter body extending between a proximal end 112 and a distal end 114, and an expandable tip 42 at the distal-most end of the retrieval catheter. The expandable tip 42 can be sized and configured to radially expand upon deployment at a target site to atraumatically contact the inner vessel wall, restrict / stop blood flow to prevent unwanted aspiration of blood near the tip, and provide a large opening for aspirating and receiving thrombus.

[0034] The flexibility of catheter 35 allows a physician to quickly create a pathway to and gain access to the vicinity of an embolus using a smaller diameter standard sheath or outer access catheter (not shown). The aspiration catheter may be of a rapid-exchange (RX) type similar to that shown in FIG. 1 , in which proximal guidewire 30 is coupled to a proximal fitting 40 of support tube 100, which defines the catheter body. The support tube may have a length 113 between a proximal end 112 and a distal end 114. Preferably, expandable tip 42 is expanded at the treatment location so that the expanded tip does not need to be advanced through the vasculature, allowing the length 113 of the support tube to be relatively short. For thrombi located in the anterior or posterior cerebral arteries, the length 113 can be greater than 5 cm to allow for extension from the outer catheter to the proximal aspect of the thrombus, but less than 40 cm to maximize the volume provided for aspiration of the combined outer / retrieval catheter while the minimum length remains inside the distal end of the outer catheter. The reduced length 113 of the distal section also improves the trackability and flexibility of the system for accessing the target.

[0035] The transition at the proximal fitting 40 may be capable of forming a seal with an outer sheath or intermediate catheter, which may be supplied with the thrombectomy catheter 35 or supplied separately. The seal allows a suction source connected to the proximal end of the intermediate catheter to be directly connected to the port of the expandable tip 42 of the thrombectomy catheter with little or no loss of negative pressure between the suction source and the port of the thrombectomy catheter.

[0036] The guidewire 30 may be solid or may be a composite of multiple layers of material, such as a solid core and an outer tubular portion (e.g., a nitinol core with an outer polymer jacket). The guidewire 30 may also be formed with features that mate with features on the proximal fitting 40 of the catheter body support tube 100 to provide a mechanical lock between the guidewire and the support tube. Heat shrink, reflow polymer, and / or adhesives may be used to reinforce the connection between the guidewire and the support tube.

[0037] The expanded, deployed configuration of the expandable tip framework 42 at the distal end 114 of the thrombectomy catheter 35 can have a flared or funnel shape. By incorporating a funnel shape into the expandable tip, the thrombus can be gradually compressed to a smaller diameter during retrieval, allowing it to be completely aspirated through the catheter into an aspiration syringe or canister. This compression reduces the likelihood that a firm, fibrin-rich thrombus will become lodged in the tubular portion of the thrombectomy catheter. If a thrombus does become lodged in the tip port, the enlarged port protects the thrombus and prevents it from being dislodged when the suction force is maintained and the catheter 35 is retracted into the sheath or outer catheter.

[0038] The funnel-shaped design of the expandable tip of the disclosed embodiments can be a one-piece lattice laser-cut directly and integrally with the support tube of the catheter shaft. Alternatively, the expandable tip lattice can be injection molded as a single piece and attached to the shaft 220 by heat welding, adhesive, or similar means. The expandable tip 42 of the thrombectomy catheter 35 can be designed to expand to a wide range of target vessel diameters, such as the distal carotid artery (3.2-5.2 mm), the horizontal portion of the middle cerebral artery (M1) (1.6-3.5 mm), and / or the internal carotid artery (ICA, 2.7-7.5 mm). When the catheter is subsequently retracted from the M1 portion to the ICA (or another path with a proximally increasing vessel inner diameter), the expandable tip 42 continues to seal the vessel over a range of vessel diameters. Furthermore, a tip capable of accommodating a range of target vessel diameters can also seal vessel bifurcations, which may have a wider cross-sectional area than the vessels proximal and distal to the bifurcation. Preferably, the expandable tip 42 of the catheter 35 is expanded at the treatment site so that the expanded tip does not have to be advanced through the vasculature.

[0039] The distal portion of the aspiration thrombectomy catheter 110 has good thrust and tracking characteristics to aid in the advancement of the distal portion to the target location. Therefore, the thrombectomy catheter can have multiple designs or be made from multiple materials to provide a decreasing stiffness profile along its length to minimize insertion and retraction forces. In one embodiment, the support tube 100 can be laser cut from hypotube and integrally formed with the expansion frame portion of the distal tip 42. In another embodiment, the support tube can be an injection-molded polymer or metal braided or woven support structure. It can also incorporate forming elements that bias bending or encourage twisting about a particular plane to reduce imparted strain. This allows the catheter to maintain good lateral flexibility but not tend to expand or kink in compression.

[0040] The catheter 35 can also have a cover or membrane disposed around or enclosing the support tube 100 and expandable tip 42. In the disclosed embodiments shown in the figures herein, the jacket or membrane is often not shown to allow for clarity of the underlying support structure, but the structure and appearance of such a membrane would be recognizable to one skilled in the art. Suitable jacket materials can include elastomeric polyurethanes, such as ChronoPrene®, which can have a Shore hardness of 40A or less, or silicone elastomers. A single or variable stiffness cover can be extruded or post-formed over the support tube 100. The cover can also be laminated or heat-welded to the structure.

[0041] Alternatively, the cover can be formed from a series of polymer jackets. By arranging different jackets or sets of jackets at distinct lengths along the axis of the support tube 100, different pushability and flexibility characteristics can be imparted to different portions of the tubular section of the catheter 35. By configuring the jackets in an axial array, the overall stiffness of the catheter can be transitioned from a stiffer proximal end to a very flexible distal end. Alternatively, by arranging the polymer jackets of the cover in a radial array around the support tube, material properties can be tailored across the thickness. In further embodiments, the transitions between jackets can be tapered or slotted to provide a smoother transition between the flexibility profiles of adjacent jackets in the longitudinal array.

[0042] To allow for smooth delivery of the thrombectomy catheter through the outer catheter, the outer surface of the membrane or outer jacket can be coated with a low-friction or lubricious material, such as PTFE or FEP. In another embodiment, a low-friction inner liner can be applied to the inner circumference of the support tube 100. Alternatively, a coating such as a lubricant (such as silicone oil or molybdenum disulfide) or a hydrophilic coating can be used. In a further embodiment, if formed from a polymer extrusion, the inner or outer surface of the membrane, or the tubular portion of the catheter body, can be impregnated with a low-friction component that migrates to the surface, thereby eliminating the need for a low-friction liner.

[0043] The support tube 100 structure of the framework 110 of the thrombectomy catheter 35 can have many different configurations. In one embodiment, the support tube 100 can have a configuration similar to that shown in FIG. 2 . The tube 100 can have one or more axial spines 116 extending axially from the proximal end 112 to the distal end 114, parallel to the longitudinal axis 111. The spines can be tubular or wire-shaped to provide high axial stiffness for advancing and retracting the catheter while providing sufficient lateral flexibility for tracking through a blood vessel. The use of multiple spines encourages bending along a defined plane while reducing the likelihood of the support tube 100 stretching under tensile loads, such as when the expandable tip is retracted into the port of the outer catheter. Along the length of one or more axial spines, multiple ribs 118 can be provided, which can be symmetrical about the longitudinal axis 111 of the thrombectomy catheter 35. Each rib 118 can define a central lumen 119. Each rib 118 can be a simple circular configuration, as shown, or can have a more complex shape as desired.

[0044] Each rib 118 and one or more axial spines 116 of the tubular support framework 110 can be formed by laser cutting tubing, such as hypotubing, or other similar structures, including strands, including braids, weaves, and / or coils, with overlapping or interwoven spines. This allows the support tube 100 to have good pushability and torque characteristics, kink resistance, resistance to collapse under suction, and reliable resistance to tensile elongation. Commonly used materials include nitinol and well-known medical stainless steel alloys such as 304 and 316. In hypotubes of different materials, such as stainless steel in the proximal section of the tubular support tube and nitinol in the distal section and dilator opening of the tubular support tube, the different materials are joined by welding, adhesives, or by interlocking features held in place by inner and / or outer polymer jacket materials.

[0045] In another embodiment, one or more of the spines 116 can be integrally formed with the distal expandable tip 42. This configuration allows the spine 116 to continue extending distally of the tube as a continuous member, thereby providing good pushability characteristics while maintaining a more gradual transition in bending stiffness between the support tube 100 and the tip 42.

[0046] Although the spine(s) 116 are shown flush with the ribs 118, it will be appreciated that the spines may be located midway between the walls of the supporting framework 110 or tangent to the interior walls.

[0047] Tailoring catheter stiffness and stiffness variations is important in situations where distances and tortuosity may be significant, such as when a catheter must be advanced from a patient's inner thigh, through the cardiac arch, and into the intracranial neurovasculature. When forming the framework 110, this stiffness can be tailored using the sizing of the cuts in the hypotube to form the ribs 118 and spines 116. For example, each rib can be cut to various widths and spacing densities. The cuts can be circumferentially continuous, terminate on either side of the axial spine 116, or be discontinuous in a repeating or non-repeating pattern around the circumference of the tubular portion. When discontinuous cuts are axially aligned, they can form one or more additional axial spines 116 to bias the bending and flexion plane of the catheter support tube 100. As a further example, when discontinuous circumferential cuts are interspersed with circumferentially continuous cuts, they can form discontinuous axial spines.

[0048] One or more portions of the support tube 100 can flare radially outward to form a seal with the inner diameter of the outer or intermediate catheter. In another embodiment, no seal or flow restriction is necessary, and the lumen between the inner diameter of the outer catheter and the outer diameter of the aspiration thrombectomy catheter 35 can be made small enough that suction losses are negligible. Alternatively, the catheter diameter can be sized such that the lumen can be configured to allow suction to be applied at two locations: at the distal end of the thrombectomy catheter and at the distal end of the outer catheter.

[0049] In other embodiments, the catheter's tubular shaft may be provided without the strut support structure, and the tubular shaft may be formed solely from polymeric portions. For example, the catheter 35 may have a shaft formed from a single polymer extrusion. The extrusion may be manufactured from, for example, polyetheretherketone (PEEK), polyimide, polyethylene, or another durable thermoplastic polymer. The surface of the extrusion may be laser cut and profiled with a series of ridges and recesses to provide enhanced torque, pushability, and compliance characteristics. The ridges or recesses may be applied by passing the polymer extrusion through a heated profiling die, which melts and cools the tube as it passes through. Prior to profiling, a composite tube may be reflowed to have a varying longitudinal stiffness profile and then passed through the profiling die to provide a uniform support structure, as desired.

[0050] Where the outer jacket has been reflowed over the laser-cut hypotube and into the spaces between each rib 118, material may protrude radially at the locations of the laser-cut struts. The shaft can then be pulled through a sizing die to remove any excess material above the struts, resulting in a consistent overall outer diameter for the shaft of the support tube 100 and a smaller delivery profile.

[0051] The one or more axial spines 116 themselves can be formed or cut to various thicknesses. Thicker spines can provide greater column strength and axial stiffness, improving the catheter's kink resistance and insertion and retraction capabilities. Conversely, thinner spines can provide greater flexibility in bending to navigate tortuous regions of the vasculature. The one or more spines can also taper in thickness along their axial length to capture both of these benefits. Tapered spines can be stiffer proximally to provide good pushability, and very flexible distally to allow the tubular portion to twist and buckle around the vascular pathway.

[0052] 3a-3d show an exemplary support tubular framework 110 tube having a single tapered spine 116 extending parallel to the longitudinal axis 111 of the support tube 100. The taper angle of the spine 116 can vary throughout the length of the tubular framework 110. The spine can have at least a distal first width or thickness 136 that is less than a proximal second width or thickness 138, as shown in FIG. 3c. The proximal thickness of the spine 116 can be thicker and more rigid than the more distal portion of the support tube to provide good pushability, while the distal portion of the framework 110 can have a thinner, more flexible spine 116 to allow the framework to twist and buckle along tortuous vascular pathways.

[0053] The use of at least one spine 116, as seen in Figure 3b, can reduce the likelihood of stretching under tensile loads, such as when the expanded catheter distal tip 42 is retracted into an outer sheath or intermediate catheter. Each rib 118 of the framework structure 110 can terminate at opposing junction points 126 on either side of the tapered spine 116. Each rib 118 can have varying strut widths and varying spacing densities between adjacent ribs to further optimize the stiffness profile of the support tube 100.

[0054] Another example of a support tubular framework 110 having two tapered spines 116 spaced 180 degrees apart is shown in Figures 4a-4d. As in Figure 3, each spine may taper at a different angle along its length, or the taper may be curved relative to the longitudinal axis 111 so that the stiffness of the support tube 100 transitions along its length. In general, the support tube 100 may be stiffer at the proximal end 112 and very flexible near the distal end 114 to ensure access as close as possible to the target site of the occlusion.

[0055] Compared to a single spine, the use of additional spines 116 can provide the framework 110 with greater resistance to localized stretching between the ribs 118 when the support tube 100 is subjected to lateral and tensile loads. The opposing arrangement of the tube spines 116 (see FIG. 4b) can encourage bending of the framework 110 in a single plane 120 extending through the two spines (see FIG. 4a). This configuration, combined with the opposing sets of junctions 126 on the ribs 118, can help transmit balanced and consistent pushing or thrust forces through the length of the catheter. Multiple spines also help the support framework resist longitudinal compression during deployment, ensuring precise placement at the treatment site. The arrangement of the spines opposite each other can also prevent the framework 110 from bending either spine in a direction perpendicular to the circumferential direction of the spine, a direction that would make the spine more susceptible to kinking or potentially breaking at locations where the strut width of the spine exceeds its thickness.

[0056] 5a-b, a support tube 100 is shown in which each rib 118 of the supporting framework structure 110 is arranged in a coiled, helical configuration centered on the longitudinal axis 111 of the support tube 100. The coiled structure can be manufactured with overlapping spines 116 as shown in FIG. 5a, or the structure can be integrally formed by laser cutting the ribs and spines into a single hypotube. In a similar example, two spines 116 can be formed 180 degrees apart along the length of the coil, as shown in FIG. 5b. The helical configuration of the two-spine rib 118 can mean that the rib's respective junctions 126 with each spine are axially offset on either side of the supporting framework structure 110.

[0057] As with other disclosed embodiments, the stiffness profile of the support tube 100 can be further optimized by varying the pitch between each rib 118. Reducing the rib pitch and increasing the rib strut thickness can each contribute to adding stiffness to specific regions of the tube, while increasing the rib pitch and / or decreasing the rib width can reduce stiffness in a given section. For example, making the more proximal rib thickness 141 greater than the more distal rib thickness 142, or making the proximal rib pitch 139 smaller than the distal rib pitch 140, can provide additional flexibility in the distal section of the catheter. Similarly, making the more proximal spine width 138 greater than the more distal spine width 136 can achieve the same effect.

[0058] The above support framework 110 parameters of the ribs 118 and spines 118, in combination with variations in the stiffness and / or thickness of the outer jacket or membrane material, can be optimized to give the catheter body effective pushability, trackability, and torque transmission in different regions of the support tube 100, thereby enabling the catheter to be delivered along the most difficult vascular pathways to reach remote target treatment locations.

[0059] 6a-d, a support tube 200 can have a framework 110 with two interrupted spines 214, with adjacent straight portions of each spine spaced 90° apart and extending parallel to the tube's longitudinal axis 111. This configuration can be formed by cutting a series of radiused radial slots 212 into alternating opposing sides of a hypotube or other tubing to form adjacent ribs 118 along the length of the support tube 200. This design effectively has interrupted spines at 90, 180, 270, and 360° locations around the framework 110, allowing the tube to bend in two perpendicular bending planes 120, 121 that are axially aligned and extend through each of the interrupted spines 214.

[0060] Having intermittent spines that define multiple bending planes allows for greater freedom of movement within a three-dimensional vascular pathway. However, such designs also have lower column stiffness and are more susceptible to axial elongation under tension, such as when the expandable port of the catheter is retracted into the outer intermediate catheter. Expansion of the support tube can prevent the port from collapsing against the trapped thrombus and exerting a more effective grip on the trapped thrombus.

[0061] Other mechanisms can be incorporated to address this. For example, one or more separate continuous wire spines (not shown) can be incorporated integrally with or separately from the support tube 200. If separate, an outer polymer jacket or membrane can be used to fuse the hypotube support framework 110 and the wire spine together. The wire spine can add structural integrity under tensile loads and prevent axial elongation of the tube when the catheter tip 42 with the enlarged port is retracted into the outer sheath of the intermediate catheter. In another embodiment, the width of the struts of the ribs 118 can be increased to adjust stiffness in a manner that can prevent undesired elongation of the support tube 200.

[0062] 7a-d, a support tube 100 can have a framework 110 with looped ribs 118 connected by a helical spine 117 extending between a proximal end 112 and a distal end 114 of the framework. A similar design is shown in FIGS. 8a-d, where two helical spines 117 extend out of phase, 180° apart from each other. The helical spine allows the support tube 100 to twist about a longitudinal axis 111 along the length of the tube.

[0063] Like discontinuous spines, helical spines also have a tendency to straighten and elongate when tension is applied to the support tube 100. To prevent elongation, the pitch of the helix can be increased so that the twisting is very gentle and locally one or more spines are nearly straight. For example, a pitch of 10 mm to 200 mm, more preferably 50 mm to 100 mm, can be used.

[0064] A composite design may have a support framework 110 in which one or more helical spines 117 are fused with portions of the framework in which one or more spines are straight relative to the axis 111. Areas of the support tube 100 having a more flexible outer cover or jacket (not shown) may be aligned with the straight spines to reduce the possibility of tensile elongation.

[0065] Where the helical spine 117 may have a junction 126 that forms an acute angle with each rib 118, a notch 128 with a large edge radius may be formed, as shown in Figure 8e. The notch 128 may provide localized strain relief at the junction 126 as the supporting framework structure 110 twists about the longitudinal axis 111.

[0066] Various views of another embodiment of the support tube 300 are shown in Figures 9a-e. The support tube 300 can have a generally tubular section, such as a hypotube or polymer extrusion, with a pattern of cuts that form radial slots 312 spaced about the longitudinal axis 111. The interruptions can be arranged so that the discontinuous sections of the cuts are axially aligned to form one or more continuous spines 314. In one embodiment, the radial slots 312 form two continuous axial spines 314 spaced 180° apart to maintain a smooth stiffness profile on alternate sides of the support tube 300.

[0067] In one embodiment, the cuts forming the radial slots 312 can be made completely around the support tube 300. By incorporating geometric elements along the circumference of the tube that form keyed interfaces with adjacent axial sections, longitudinal and torsional loads can be transferred without a spine. The keyed interfaces can be dovetailed or similarly configured to allow the support tube body to fit together like a puzzle. In a similar embodiment, the keyed interface can be maintained, but the radial slots 312 can be cut with discontinuities to create continuous or discontinuous spines for situations where additional pushability is desired.

[0068] In some cases, as seen in FIGS. 9b and 9c, the radial slots 312 can be spirally configured and include an alternating pattern of interruptions, such that the radial slots form one or more intermittent spines 315 angularly offset from one or more continuous spines 314. Thus, the spiral cut pattern can have one or more radial cuts per revolution 316 about the longitudinal axis 111. In the embodiment shown in FIG. 9e, three cuts per revolution are used. Each of the cuts or radial slots 312 can be cut at a constant length, or varying lengths can be used to provide lateral flexibility for the support tube 300 in multiple planes. Pattering the radial slots 312 to incorporate both continuous spines 314 and intermittent spines 315 minimizes the likelihood of the support tube 300 stretching under tension.

[0069] Another support tube 300 using a hypotube or polymer extrusion with radial slots 312 cut into the tubular portion is shown in Figures 10a-b. Each cut can be planar with a transverse axis on alternate sides of the support tube 300. The radial slots 312 can terminate or transition into transverse cuts to form an "I" or "T" pattern defining one or more continuous axial spines 314. The transverse cuts in the pattern can function as strain relief notch 128 mechanisms that vary in thickness and increase the free length of one or more spines, thereby allowing the support tube 300 to bend more easily around the bending plane. As shown in Figure 10b, each I-slot 316 and each T-slot 317 can alternate in an offset pattern on either side of the spine, forming two continuous spines spaced 180° apart. The two continuous spines allow the support tube 300 to maintain substantial longitudinal stiffness along the axis 111.

[0070] Flat patterns illustrating variations of support tube 300 having T-slots 317 and strain relief notches 128 are shown in Figures 11a and 11b. Each T-slot 317 can be cut at an angle, as shown, or at a curve, so that the resulting member is a profiled rib 320 that varies in thickness about the tube's longitudinal axis 111. As seen in Figure 11a, profiled rib 320 can be wider near opposing successive spines 314 and narrower midway between the spines. This configuration provides more room for ribs 320 to move in flexion while providing additional support for tube 300 against vacuum pressure under suction.

[0071] In another embodiment, the strain relief notches 128 in the ribs 320 can be T-slots 317 with a gentle curve or radius in the spine 314, such as those shown in Figure 11b. The curved T-slots can provide additional flexibility to the support tube 300 by encouraging bending tangential to the curve, while allowing more room for the contoured ribs 320 to bend proximally or distally relative to one another in tortuous vessels.

[0072] 12a-d show another example of a support tube 100 that may have a scaffold 110 machined from a tube with a single axial spine 116 anchoring a number of ribs 118 extending between a proximal end 112 and a distal end 114. The spine may have at least a distal first width or thickness 136 that is less than a proximal second thickness width 138, thereby providing the scaffold 110 with good pushability proximally and a more flexible spine distally for twisting and flexing through a vascular pathway.

[0073] Each rib 118 can be cut at an angle 130 so that each free end extends distally relative to the rib junction 126 with the spine 116. Although the ribs 118 are angled, they can maintain a circular inner lumen 119 (as seen in FIG. 12d) and outer diameter. This configuration allows each rib 118 to move proximally relative to the spine 116 when compressed between each junction 126 and a stiff thrombus that resists stretching into the nominal resting inner diameter of the scaffold 110. This compressive force transmitted to the distal-most rib can be transmitted proximally to adjacent ribs by an outer covering and / or jacket (not shown) disposed around or encapsulating the scaffold. The jacket can reflow against the cut-out supporting scaffold 110, allowing the jacket to position itself between adjacent ribs 118 and transmit longitudinal loads between them. The jacket may be made of a polymer and be elastic so that it stretches and expands in diameter in response to rib movement. Compressive forces from the thrombus increase the cross-sectional area of lumen 119 as the ribs move proximally to a position where rib angle 130 is more perpendicular to spine 116 and longitudinal axis 111 and the elastic jacket expands radially outward, temporarily increasing the receiving space available for thrombus capture.

[0074] One illustrative example of how a support tube 100 similar to that of FIGS. 12a-d can be further tuned to further optimize delivery characteristics is shown in FIGS. 13a-13d. Variable-stiffness sections of the support tube can be connected by variable-width spines 116, where the proximal rib pitch 139 of ribs 118 in the more proximal axial section is greater than the distal rib pitch 140 in the more distal axial section. The spines 116 can have a first spine width 136 near the distal end 114 that is smaller than a second spine width 138 near the proximal end 112 of the support framework structure 110, thereby increasing the distance between the respective junctions 126 between the spine and each rib 118. It will be appreciated that the spines can taper to other intermediate widths between the first and second widths. The ribs themselves can also be cut to different thicknesses within different axial sections of the support framework structure 110, or formed with different thicknesses at different clock positions about the longitudinal axis 111, as desired.

[0075] A support tube 100 similar to the embodiment of Figure 13a is shown connected at its distal end 114 to the scaffolding of a self-expanding catheter tip 42 in Figure 14. The struts of this scaffolding can be made of nitinol or another shape-memory material with sufficient elastic strain capacity so that the tip does not exceed its elastic limit when constrained in a collapsed configuration within an outer catheter and delivered. Additional scaffolding structures of wire or non-superelastic material can also be envisioned, requiring lower strains to move from a collapsed state for delivery to an expanded state for thrombectomy.

[0076] The spines 116 of the supporting framework 110 can transition directly into one or more struts of the spine extension 44 at the distal end 114; having the spines integral with the extension (e.g., cut from the same hypotube) can provide a smoother stiffness profile for the catheter and eliminate weak transitions. The support arms 45 of the expandable tip 42 can extend distally from a central junction with the spine extension 44, or one or more of the arms can connect to the distal-most rib of the supporting framework 110. Each arm can connect to other struts or can itself include radial bends to form the periphery of the enlarged distal port 46 of the catheter tip 42. The support arms 45 can be configured to expand radially outward when a clot is aspirated or when a clot removal device is retracted through the port 46, for example, to increase success when targeting a tough clot.

[0077] Each support rib 118 of the support tube 100 can be formed at an angle relative to the axis of the tube so that each rib has a generally cylindrical profile but does not have a planar cross-section. If each support arm 45 of the tip 42 is not directly connected to the distal-most rib, the free end of each rib 118 can move proximally relative to the longitudinal spine 116 under compressive loads, such as when retracting a thrombus. Proximal movement of each rib 118 can have the effect of locally expanding the inner diameter of the catheter lumen 119 as a thrombus is retracted through the support tube. The elastomeric outer jacket or membrane covering the support framework 110 and the expandable tip 42 can be configured to allow the support arms 45 and ribs 118 to expand under these compressive loads.

[0078] One embodiment of a support tube 100 having a tubular support framework 110 with axially curved ribs 118 spaced between two consecutive spines 116 spaced 180° apart is shown in Figures 15a-d. Each rib 118 can have a proximal peak 136 that defines the proximal-most point where the rib intersects with the spine 116 at each junction 126. The profile of the rib 118 beyond the junction 126 can have a gently undulating, non-planar cross-section that can have one or more bends but still define a generally cylindrical catheter lumen 119. As shown in the isometric view of Figure 15a, the rib profile can have a first proximal bend 132 radially offset from the proximal peak 136 and a second distal bend 134 radially offset from the proximal bend and culminating in a distal peak 138, such that at least a portion of the rib is distal to the connection at the junction 126. It will also be appreciated that the corresponding junction 126 with each spine 116 may also be axially offset proximally or distally relative to the opposing junction with the other spine. The ribs 118, which form a generally cylindrical profile but do not have a planar cross-section, have the ability to expand under compression during the drawing of thrombus from the blood vessel into the inner lumen 119 of the catheter, thereby allowing this form of the support framework 110 to "swallow" dense thrombus that would otherwise be restricted from entering a non-expanded form.

[0079] The supporting framework 110, having ribs 118 with one or more axial bends, can be configured with a spine 116 at its distal end 114 that is collinearly connected to the support arms 45 of the framework of the dilatation catheter tip 42, as shown in FIG. 16 . The collinear connection between the arms 45 and the spine 116 allows the forward force to be transmitted directly along the spine to the support arms as the catheter is advanced through the outer intermediate catheter, enhancing pushability. This configuration also allows the distal peak of each rib 138 to remain free, so that frictional and compressive forces generated between the supporting framework 110 and the outer catheter during advancement, as the expandable tip presses radially outward against the outer catheter, are not transmitted in a direction that would expand the ribs. This expansion could otherwise cause at least a portion of the support tube 100 to press against the inner surface of the outer catheter, increasing friction and adversely affecting deliverability.

[0080] A support tube 100 can be seen in Figures 17a-d having a support framework 110 similar to that of Figures 15a-c, but with ribs 118 extending circumferentially in a wave-like pattern. Each rib 118 may intersect at each junction 126 with two offset spines 116 spaced 180° apart in a generally perpendicular fashion. Thus, the proximal and distal curved portions 132, 134 of each rib may form a proximal peak 136 circumferentially offset from each spine 116. The distal peak 138 of each rib may remain free, allowing each rib to flex independently. This wave-like pattern creates more contact points between the ribs 118 and the outer jacket or membrane, distributing forces more evenly around the circumference while still preserving the ability to expand under compression. It will also be appreciated that the strut widths of the ribs and spines can be varied and the corresponding joint points axially offset on each spine to further adjust the movement of the ribs 118 and the stiffness profile of the supporting framework 110.

[0081] 18a-d show an example in which the ribs 118 of the supporting framework 110 can have proximal and distal curves 132, 134 that curve in the opposite direction to the ribs in FIGS. 17a-d. Because the corrugations of the support tube's ribs allow the tube to expand, a tough thrombus that cannot be pushed into the device's nominal resting inner diameter can instead be retrieved by radial expansion of the supporting framework 110, which can occur when suction is maintained on a stuck or incompressible thrombus. As with other embodiments, the outer jacket or membrane covering the supporting framework 110 can be formed of an elastomeric material to allow unrestricted expansion of the support tube. The use of two spines 116 in embodiments in which the ribs have a circumferential corrugated or wave-like pattern can provide better pushability than a single spine while preventing the support tube 100 from stretching under tension as the expandable tip 42 is retracted proximally into the outer intermediate catheter.

[0082] An additional feature that facilitates movement of the ribs 118 and the overall flexibility of the supporting framework 110 includes enlarged openings or notches 128 at each junction 126 of the framework. The notches 128 increase the ability of individual ribs to move relative to one or more spines 116 while providing interfacial strain relief. A highly flexible catheter can reduce the risk of cracking or ultimate failure by reducing geometric stress concentrations at each junction through the strain relief notches 128. The notches 128 at each junction 126 encourage each rib to flex independently, thereby more effectively absorbing procedural loads.

[0083] Various additional geometric shapes for strain relief notch patterns can be seen in Figures 19a-c. These features can be introduced into the hypotube support tube 100 by incorporating additional processing steps into the rib cuts, or they can be cut or integrally formed when the support tube is extruded or injection molded. Depending on the flexibility preference for a particular axial portion of the tube support framework 110, users can introduce chamfered or rounded strain relief notches 128 at the corners of each junction 126, as shown in Figure 19a. Such notches can be particularly useful in situations where rib spacing is very dense and there is insufficient space for other stress-reducing shapes. When the rib pitch is large, stress can be further reduced by using notches 128 at each junction 126 with an expanded, larger radius, as shown in Figure 19b. Similarly, tight rib spacing can be maintained by providing smaller relief notches 128 at the corners of the junctions 126, as shown in Figure 19c.

[0084] To improve the multiaxial flexibility of a support tube, it is often advantageous to minimize the overall number of connections to one or more spines. Figures 20a-c illustrate several embodiments in which a support tube 100 has a support framework 110 in which a series of support ribs 118 converge into a single spine connector 146 to connect to one or more spines. Each set of support ribs can include one, two, three, or more ribs 118. In Figure 20a, a pair of ribs 118 has opposing wing-like portions 147 that curve or taper toward the spine connector 146 where they connect to the spine 116. Connecting multiple support ribs 118 as a set with a single connection to one or more spines 116 allows a longer length of the spine to bend freely for a given density of ribs. A similar concept is shown in Figure 20b, using three ribs 118 connected to a single connector. The outer ribs of this set may have winged portions 147 to meet the central rib, which may have a direct connection with the spine connector 146.

[0085] As shown in FIG. 20c, a series of support ribs 118 can merge into opposing spine connectors 146 to connect two spines 116 spaced 180° apart. Additional spines are also envisioned. Two opposing spines can provide better pushability than a single spine while preventing the support tube 100 from stretching under tension, such as when the expandable tip 42 is retracted proximally into the outer catheter. Fewer connections to the spines can provide the framework 110 with better flexibility for bending along bending planes that pass through the longitudinal axis 111 and each of the spines 116.

[0086] A further embodiment of a support tube 400 having a different configuration in which the radial slots form a puzzle-cut pattern is shown in FIG. 21a. The puzzle-cut tube can essentially be a series of interlocking ribs or rings 403. Because each ring 403 is not integral with either the proximal or distal adjacent ring, the puzzle-cut tube can twist about the longitudinal axis 111. The structure of the puzzle-cut support tube 500 can also resist tensile elongation due to the interlocking of adjacent interlocking mechanisms 404, 405. The distal interlocking mechanism 405 can interlock a particular ring with the next distal ring, and the proximal interlocking mechanism 404 can interlock with the next proximal ring.

[0087] The flexibility of the puzzle-notch support tube 400 can be varied by increasing or decreasing the size of the linking elements 406 between the linking features of each ring 403. FIG. 21b illustrates how flexibility can also be varied by varying the number, shape, and / or spacing of the linking features 404, 405. The longitudinal spacing 408 and circumferential spacing 410 between adjacent rings 403 can be controlled by the thickness of the notches or by machining operations. Thus, the support tube can be made longer by the sum of the longitudinally distributed spacings 408. Similarly, the circumferential spacing 410 can be varied to adjust the allowable kink. The torsional characteristics provided by the puzzle-notch design of the support tube aid in the bending and torque transmission of the catheter in multiple planes as the support tube is advanced through tortuous vascular pathways.

[0088] 21c and 21d show that the support tube 400 can have a puzzle-cut design with an interlocking mechanism while incorporating a longitudinal spine 416. As seen in FIG. 21d, the spine 416 can be added by aligning interrupted portions of the puzzle-cut radial slots, thereby longitudinally securing each ring 403 at the spine. It will be appreciated that portions of the spine 416 may be circumferentially offset, or the spine thickness may vary at different axial locations along the length of the support tube 400. The addition of the longitudinal spine 416 helps prevent the puzzle-cut tube from stretching under tensile loads. Furthermore, the single spine has minimal impact on the ability of the puzzle ring 403 to twist, allowing the catheter support tube to maintain its compliance benefits.

[0089] 21e and 21f, the puzzle-notched support tube 400 can have two longitudinal spines 416 spaced 180° apart. The addition of the two spines 416 prevents the support tube from stretching under tensile loads and provides a preferred bending plane for the tube. When aligned parallel to the longitudinal axis 111 as shown, the two spines spaced 180° apart have minimal effect on the puzzle ring's ability to twist; twisting changes the tube's preferred bending position to an extent controlled by the twist in the design, allowing the support tube to self-adjust as it is advanced through tortuous vessels.

[0090] In another embodiment, as shown in Figure 22a, the support tube 500 can comprise a metal and / or polymer strand or wire structure formed into a braided or coiled structure 510. The strands 511 of the braid pattern 510 can be formed into a continuous radial arrangement that generally approximates a single main support member and can be dense enough to support the outer membrane, similar to laser cut hypotubes. Each strand 511 of the support tube 500 can be formed on a straight mandrel such that one or more sections of the tube expand radially outward to form a seal with the inner diameter of the outer or intermediate catheter.

[0091] Braided structures are well known in the art to provide good flexibility for optimizing catheter tubing performance. However, while braids tend to stretch and reduce their cross-sectional diameter under tension, they can expand in diameter and shorten under compression. In the disclosed design of FIG. 22b, one or more woven spines 516 can be incorporated into the braid. The spines 516 prevent the braid pattern 510 from stretching under tension or shortening under compression. Alternatively, for simpler manufacturing, one or more spines 516 can be superimposed on the braid pattern 510. The spines 516 can be bonded in place with an adhesive or other suitable method.

[0092] This expansion can be achieved by varying the size, orientation, or other characteristics of each strand 511 in the pattern 510. Further flexibility can be achieved by varying the braid angle 512 or picks per inch (PPI) of the pattern. The braid angle 512 of the strands 511 and the density of the pattern can be selected to suit the desired axial and transverse mechanical properties of a given portion of the support tube 500. For example, the braid angle and / or PPI can be different in a more proximal portion of the support tube, thereby providing the proximal portion with better pushability and torque response than the more flexible distal portion.

[0093] In one embodiment, the braid angle 512 can be less than 90° and greater than 20° so that the support tube 500 has freedom to compress longitudinally. Maintaining a braid angle closer to 90° provides the framework with more flexibility than braid angles closer to 20° because the wires or strands of a 20° braid are more dispersed longitudinally. Braid angles 512 greater than 90° can also expand, but to a lesser extent due to the closer spacing between the braid strands 511.

[0094] As with other embodiments, the braid pattern 510 can have an elastomeric outer covering or jacket (not shown). The jacket can be reflowed onto the outer surface of the braided tube or formed to encapsulate the strands 511. The reflowed jacket material fills voids between the braid pattern 510 and the spines 516, further reducing the tube's ability to expand or contract. Encapsulating the pattern 510 with a reflowed polymer jacket can also help hold the braid and spine(s) 516 together. The jacket can be impermeable, or the braid or coiled pattern 510 can be dense enough to substantially prevent fluid flow between the exterior and interior of the support tube, thereby eliminating the need for an impermeable cover or seal.

[0095] Any of the support tubes for the thrombectomy catheter designs disclosed herein can be used with a mechanical thrombectomy device. Combining mechanical thrombectomy with aspiration through the funnel-shaped tip can increase the chances of first-pass success in thrombus removal. During thrombectomy, the funnel-shaped tip configuration reduces shearing of the thrombus as it enters the catheter, halting flow and protecting the distal vessel from embolization of new areas. Furthermore, the mechanical thrombectomy device can direct aspiration vacuum to the thrombus surface while holding the composite thrombus (consisting of weak and fibrin-rich regions) together, thereby preventing embolization and helping to slough the thrombus away from the vessel wall. The tip configuration can also help prevent fragmentation if the thrombus enters an offset position at the catheter port.

[0096] The mechanical thrombectomy device can support the lumen of the blood vessel during aspiration to prevent collapse under negative pressure, holding the thrombus together when the thrombus contains many hard and soft segments that could fragment. The mechanical thrombectomy device also allows the user to pinch any thrombus that does not fit completely into the lumen of the thrombectomy catheter, thereby preventing the thrombus from falling out of the thrombectomy catheter as the thrombectomy catheter, thrombus, and mechanical thrombectomy device are pulled together through the vasculature, through the outer catheter, and out of the patient. The interaction of the outer catheter with the enlarged port helps gradually compress the thrombus so that it can be pulled through the outer catheter along with the thrombectomy catheter and mechanical thrombectomy device. If the thrombus is still too large to fit into the outer catheter, the thrombectomy catheter and mechanical thrombectomy device can be retracted proximally through the blood vessel into a second, larger-diameter outer catheter, such as a balloon guide. If the thrombus is still too hard to retrieve through the second outer catheter, the entire device can be retracted together as a unit through the vasculature and out of the body. The thrombectomy catheter can be designed to work with an outer catheter, such as a 7Fr, 8Fr, 9Fr, or 10Fr long guide sheath or balloon guide sheath. Alternatively, the thrombectomy catheter can be designed to work with an outer catheter, such as a 4Fr, 5Fr, or 6Fr midcatheter.

[0097] 23 and 24 are flow diagrams including method steps for manufacturing a thrombectomy catheter with a support tube according to various embodiments of the present disclosure, which method steps may be applied by any of the exemplary systems, tools, and / or devices described herein or by means known to those skilled in the art.

[0098] Referring to method 2300 outlined in FIG. 23 , step 2310 describes the task of arranging a plurality of ribs along a length, each rib oriented circumferentially about a longitudinal axis to define a generally tubular support. The ribs can be circular, spiral, or any other suitable shape suitable for intravascular procedures. The ribs can be formed by laser cutting hypotubes, cutting radial slots into extruded tubing, or other methods commonly known in the art. Step 2320 includes forming or arranging a plurality of ribs so that the flexibility of the tubular support varies along at least a portion of the longitudinal length of the tubular support. For example, the varying flexibility of the tubular support can be achieved by adjusting various rib characteristics, such as rib spacing, different thicknesses of the rib struts, and adjusting the planar cross-sectional shape of the ribs. In step 2330, the plurality of ribs can be cut or formed at one or more angles that are not perpendicular to the longitudinal axis of the tubular support. When the tubular support is subjected to tensile or compressive loads during a thrombectomy procedure, the angled orientation of the ribs can change the cross-sectional size of the inner catheter lumen to facilitate thrombectomy and / or aspiration.

[0099] Step 2340 can include forming one or more spines extending along the length of the tubular support and attaching each rib of the plurality of ribs to one or more spines. The spines can be mechanically connected to the ribs, or the spines and ribs can be integrally formed by machining the hypotube or cutting radial slots into the extruded tube. By having fixed junctions or attachment points with one or more spines, the ribs can be configured to move proximally or distally relative to the one or more spines as different intraoperative forces act on the tubular support, as in step 2350. This movement can locally increase the diameter of the tubular support as a clot is extracted or reduce frictional forces generated when a thrombectomy catheter is advanced or retracted through an outer catheter. It will be appreciated that different configurations of the ribs and spines of the tubular support can facilitate rib movement, such as narrowed rib struts or the use of a single axial spine to provide each rib with an unconstrained free end.

[0100] Referring to method 2400 outlined in FIG. 24, at step 2410, one or more spines of a tubular support are oriented to share a longitudinal axis of the support tube. For example, a straight axial spine can share an axis parallel to the longitudinal axis of the tubular support, or a helical spine arrangement can have a twist concentric with the longitudinal axis of the tubular support. At step 2420, the spines can be cut or shaped to vary the flexibility of the tubular support along its length. Transitioning the spine's thicker proximal width to a thinner width can maintain good tracking characteristics within the vessel while providing the distal portion of the tubular support with the increased flexibility needed for access.

[0101] A further step for fabricating a tubular support for a thrombectomy catheter is shown at step 2430, which can include fixedly attaching or integrally forming a radially expanding tip to the distal end of the tubular support so that the catheter has a large, distally facing port that can form a seal with the vessel and locally restrict / stop flow upon deployment. At step 2440, at least a portion of the tubular support and expandable tip can be covered with a polymeric covering. For example, the covering can be a series of outer jackets reflowed, injection molded, or laminated onto the outer and / or inner radial surfaces of the ribs. Those skilled in the art will also appreciate that a coating process can impart lubricious, low-friction properties to the surfaces of the tubular support and / or covering.

[0102] The present invention is not necessarily limited to the described examples, which may vary in configuration and details. The terms "distal" and "proximal" are used throughout the foregoing description and are meant to refer to a location and direction relative to the treating physician. Thus, "distal" or "distally" refers to a location away from or a direction away from the physician. Similarly, "proximal" or "proximally" refers to a location closer to or a direction toward the physician. Furthermore, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0103] The term "about" or "approximately" used herein in connection with any numerical value or range of values indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function in accordance with its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values of ±20% of the recited value; for example, "about 90%" may refer to a range of values of 71% to 99%.

[0104] In describing exemplary embodiments, technical terminology is employed for the sake of clarity. Each term is intended to have its broadest meaning as understood by one of ordinary skill in the art and is intended to include all technical equivalents that similarly operate to achieve similar purposes without departing from the scope and spirit of the present disclosure. It should also be understood that a reference to one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those explicitly identified steps. Some steps of a method can be performed in an order different from that set forth herein without departing from the scope of the disclosed technology. Similarly, it should also be understood that a reference to one or more components in a device or system does not preclude the presence of additional components or intervening components between those explicitly identified components. For the sake of clarity and conciseness, not all possible combinations have been listed; such modifications will often be apparent to those skilled in the art and are intended to be within the scope of the following claims.

[0105] [Embodiment] (1) A tube forming the body of a catheter assembly, A tubular support framework structure having a proximal end, a distal end, and a longitudinal axis, one or more spines extending longitudinally between the proximal end and the distal end; a plurality of ribs disposed along a length of the one or more spines and extending through the supporting framework to define a lumen of the supporting framework; a junction connecting one or more ribs of the plurality of ribs to the one or more spines; a polymeric cover disposed around at least a portion of the supporting framework. (2) The tube of embodiment 1, wherein at least one of the one or more spines has a proximal spine width that is different from a distal spine width between the proximal end and the distal end of the supporting framework structure. (3) The tube of claim 1, further comprising a spacing between adjacent ribs that varies between the proximal and distal ends of the supporting framework. (4) The tube of embodiment 1, wherein the ribs are arranged in a spiral configuration along the length of the one or more spines. (5) The tube of embodiment 2, wherein the one or more spines are arranged as a helical spine in a helical configuration centered on the longitudinal axis of the supporting framework.

[0106] (6) The tube of claim 1, wherein at least one of the plurality of ribs has a first rib width that is different from a second rib width of another rib of the plurality of ribs. (7) The tube of claim 1, wherein the ribs are disposed at an angle of less than 90° relative to the longitudinal axis of the supporting framework. (8) The tube of claim 1, wherein the junction includes a notch configured to relieve strain on the supporting framework at the junction. (9) The tube of claim 1, wherein the rib has a non-planar cross section in which the profile of the rib includes one or more curves. (10) The tube of embodiment 1, wherein two or more of the plurality of ribs meet at a spine connector having a single junction with each of the one or more spines.

[0107] (11) A tube forming the body of a catheter assembly, a tubular support framework structure having a proximal end, a distal end, an interior lumen, and a pattern of radial slots configured about a longitudinal axis; a polymer cover disposed around at least a portion of the supporting framework. (12) The tube of embodiment 11, further comprising two interrupted spines formed by patterning adjacent radial slots offset by 90°. (13) The tube of embodiment 12, wherein the intermittent spines are configured to define two bending planes that are aligned perpendicularly along the longitudinal axis. (14) The tube of embodiment 11, wherein the radial slots include a spiral pattern, and the slots are aligned to form one or more continuous spines. (15) The tube of claim 11, wherein the radial slots extend completely around the longitudinal axis of the tubular support framework, and the radial slots form a series of axial rings between the proximal and distal ends.

[0108] (16) The tube of claim 15, wherein the rings have a coupling mechanism configured to engage adjacent rings. (17) A support tube for a catheter body, a generally cylindrical braid pattern formed by a plurality of strands about a longitudinal axis, the braid pattern defining a lumen of the support tube extending through the support tube; one or more spines extending longitudinally along the braid pattern between the proximal and distal ends; a polymer cover disposed around at least a portion of the braid pattern. (18) The support tube of embodiment 17, wherein at least one of the one or more spines is interwoven with the strands of the braided pattern. (19) The support tube of embodiment 17, wherein the angle formed by the braiding of the strands of the braid pattern is in the range of about 20 to 90 degrees. 20. The support tube of claim 17, wherein the polymer cover encapsulates at least a portion of the braid pattern.

Claims

1. A tube forming the body of the catheter assembly, A tubular support framework structure having a proximal end, a distal end, and a longitudinal axis, one or more spines extending longitudinally between the proximal end and the distal end; a plurality of ribs disposed along a length of the one or more spines and extending through the supporting framework to define a lumen of the supporting framework; a polymer cover disposed around at least a portion of the supporting framework structure; the supporting framework structure further includes a spine connector, the spine connector having a junction point where the spine connector joins three or more of the plurality of ribs, and a junction point spaced from the junction point where the junction point joins one of the one or more spines; the three or more ribs include a central rib, a distal rib located distally of the central rib, and a proximal rib located proximally of the central rib; the distal rib has a first curved portion that curves proximally toward the confluence, and the proximal rib has a second curved portion that curves distally toward the confluence; A tube wherein the central rib is at the same position in the longitudinal direction as the spine connector, and the central rib has no curved portion curving in the proximal direction and no curved portion curving in the distal direction.

2. The tube of claim 1 , wherein at least one of the one or more spines has a proximal spine width that is different from a distal spine width between the proximal end and the distal end of the supporting framework structure.

3. The tube of claim 1 , further comprising a spacing between adjacent ribs that varies between the proximal and distal ends of the supporting framework structure.

4. The tube of claim 1 , wherein the ribs are arranged in a spiral configuration along the length of the one or more spines.

5. The tube of claim 2 , wherein the one or more spines are arranged as a helical spine in a helical configuration about the longitudinal axis of the supporting framework.

6. The tube of claim 1 , wherein at least one of the plurality of ribs has a first rib width that is different from a second rib width of another rib of the plurality of ribs.

7. The tube of claim 1 , wherein the ribs are disposed at an angle of less than 90° relative to the longitudinal axis of the supporting framework structure.

8. The tube of claim 1 , wherein the junction includes a notch configured to provide strain relief for the supporting framework structure at the junction.

9. The tube of claim 1 , wherein the rib has a non-planar cross section in which the profile of the rib includes one or more curves.

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