Tubular support for 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] The present disclosure generally relates to devices and methods for removing acute obstructions from blood vessels during intravascular medical procedures. More particularly, the present disclosure relates to retrieval aspiration catheters.

Background Art

[0002] Aspiration and thrombectomy catheters and devices are often used for mechanical thrombectomy to perform endovascular intervention when a patient has conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). In the conventional technology, access particularly to the neurovascular bed has been difficult due to the small diameter of the target vessel, its distance from the insertion site, and the high tortuosity of the vessel path.

[0003] Delivering an effective device to the thin, highly branched cerebral arterial system requires conventional catheters to balance many factors. A catheter must be sufficiently flexible to advance through and withstand large bending strains along the vascular structure, while also having axial stiffness to provide smooth, stable advancement along the path. New designs have been introduced that utilize various methods to vary the stiffness between the proximal and distal portions of the catheter. However, abrupt changes in stiffness or shape can impair trackability, create large stress concentrations, and potentially increase the risk of device kinking or buckling.

[0004] When aspirating with conventional fixed-mouth catheters, that is, catheters that are not sealed against the outer catheter, a significant portion of the aspiration flow is drawn from vascular fluid near the tip of the catheter where no thrombus is present. This significantly reduces aspiration efficiency and lowers the success rate of thrombectomy. For example, fibrin-rich firm thrombi can become clogged at the tip of conventional fixed-mouth catheters, which can often make them difficult to remove. This clogging can cause softer portions of the thrombus to tear away from the firm region.

[0005] Other designs for aspiration catheters feature a large-diameter, distally facing orifice to achieve maximum efficiency. For example, the orifice may be designed to have a significantly larger diameter than that of a typical delivery catheter or sheath. As a result, the orifice must not only be flexible and low-profile for delivery within the outer catheter, but also expand to the target site and enlarge to an enlarged form at the target site. The catheter's support tube must have sufficient flexibility for access, while also having the ability to effectively transfer thrust load to the distal tip orifice.

[0006] However, many highly flexible body designs have small diameters that cannot generate the required suction force, while designs with expandable components or separate suction extensions may lack the flexibility to navigate neurovascular pathways intact. Catheter elements must not only withstand the large mechanical strains acting upon them, but also generate sufficient radial force during expansion to prevent the catheter and blood vessels from collapsing under the suction force. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This design aims to provide an improved retrieval catheter with an expandable tip that incorporates these features to overcome the aforementioned difficulties. [Means for solving the problem]

[0008] The designs herein may be for thrombectomy catheters having a main support tube portion that is adjustable to have sufficient flexibility to travel along highly tortuous regions of anatomical structures such as neurovascular systems and reach occlusive thrombi. The support tube may have an expandable catheter tip having a large opening facing the thrombus, capable of locally restricting / stopping flow within the target vessel, or the support tube may be attached thereto. The catheter may also be compatible with relatively low-profile access sheaths and catheters for further delivery advantages.

[0009] A thrombus retrieval catheter may have a substantially tubular body with a supporting framework structure defining its longitudinal axis. A large-diameter catheter lumen may be configured to allow the passage of a guidewire, microcatheter, stent retrieval device, and other such devices. The lumen may also guide aspiration to the catheter tip. The tubular body may extend from a proximal end and terminate at a distal end, where an expandable tip may be integrally formed or fixedly connected. The tip may be configured to expand from a folded delivery configuration to an expanded deployment configuration when deployed at the site of an occlusive thrombus.

[0010] The support frame structure may have one or more axial spines extending longitudinally from the proximal end to the distal end. A series of loop ribs may be arranged along at least the length of one or more longitudinal spines. Each rib of the support frame structure may define the internal lumen of the catheter extending through it. Each rib may intersect with one or more spines at a junction. The junction may have a strain-relieving notch mechanism or similar shape to relieve stress at the rib-spin junction as the catheter traverses a meandering vessel within the vascular structure. In some cases, instead of having independent junctions, the flexibility of the support tube may be improved by integrating multiple ribs into a spine connector to minimize connections with the spines. The ribs may have curved or tapered wing-like portions that merge into a spine connector having a single junction with each rib.

[0011] The ribs and spines can be monolithically formed by laser processing of hypotube or extrusion molding of polymer tubes. In another embodiment, the tubular body may be a metal braid or coiled wire structure. The spines may be fixedly connected to a portion of the expandable end or formed integrally with it.

[0012] At least a portion of the tubular section can seal to the outer catheter or form a flow restriction so that aspiration is directed to the distal tip of the thrombectomy catheter. A polymer cover or membrane can surround the catheter body by positioning it around the support framework and at least a portion of the tip. In another embodiment, the cover may be a series of polymer jackets having variable stiffness and flexibility. The cover can be reflow, bonded, and / or sutured to the framework of the support structure. The cover can be further coated with a low-friction layer or film to improve conformability and reduce the risk of adhesion or excessive friction when delivered through the outer catheter.

[0013] The conformability and flexibility of the catheter within the vascular structure can be adjusted by modifying the characteristics of the support tube. For example, the bending plane of the support tube can be defined by the position of the axial spines when one or more spines are linear and parallel members. In another embodiment, one or more spines can be arranged in a spiral or helical pattern around the longitudinal axis of the support tube. One or more spines may have a different width in the more proximal portion of the support tube than in the more distal portion. The transition from one spine width to another may be a continuous taper, or it may be a transition between axial portions of a framework structure where flexibility gradually increases.

[0014] The struts forming the ribs of the support tube's frame structure can have varying widths, with the first rib width of one rib being different from the second rib width of another. The ribs may also be in a helical pattern, and the rib-to-spine connection points can be offset by a coil-like structure. The spacing between adjacent ribs, i.e., the pitch, may vary between the proximal and distal ends of the support frame structure, so that one segment of the frame structure has a denser rib pattern with higher rigidity than another segment with a larger rib spacing.

[0015] In another embodiment, the ribs may be cut or formed to be positioned at an angle not perpendicular to the longitudinal axis of the support frame structure, thereby allowing the diameter of the internal lumen to change as the ribs move in response to tensile or compressive forces on the support tube during thrombectomy. The ribs may be formed such that the ribs have a non-planar cross-section and the cross-sectional shape of the rib struts has one or more proximal and / or distal curved or wavy sections. The ribs may also be configured to move relative to their respective junctions with one or more spines, thereby allowing the support tube to expand locally to allow rigid or incompressible trapped thrombi to pass through.

[0016] In another embodiment, the support tube for forming the body of the catheter assembly may have a tubular support frame structure having a pattern of radial slots configured around the proximal end, distal end, internal lumen, and longitudinal axis. The radial slots can be cut into the outer circumference of a polymer tube extruded through at different clock positions, thereby making the radial slots discontinuous and not extending completely around the circumference. The cuts can form slots of a fixed or variable length. By aligning the segments of the cuts, the slots of the support tube can define discontinuous spines extending along the length of the tube, or continuous spines, or both discontinuous and continuous spines.

[0017] In one embodiment, adjacent intermittent radial slots offset by 90° from each other can form two intermittent spines. When offset in this manner, the two intermittent spines can define two bending planes that are orthogonal to each other and aligned perpendicularly through the longitudinal axis of the support frame structure. Further spines and bending planes can be formed by interrupting the cuts at further positions along the outer circumference of the tube and, if desired, axially aligning or offsetting adjacent cuts.

[0018] In another case, radial slots can be cut into a helical pattern, and adjacent spiral winding cuts are aligned to form one or more continuous and / or discontinuous spines. In one embodiment, the helical pattern of discontinuous slots may include at least two cuts per revolution. In another embodiment, the helical pattern may include more than two cuts per revolution to form both continuous and discontinuous spines that are offset from each other in the circumferential direction. Multiple cuts per revolution can provide flexibility along multiple different planes.

[0019] The radial slots of the support tube may extend almost 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 of varying length. Individual rings can be connected to adjacent rings via a series of coupling mechanisms along the outer circumference of each ring. Distal coupling mechanisms can mesh a particular ring with the next distal ring, and proximal coupling mechanisms can mesh with the next proximal ring. The overall flexibility of the tube can be changed by changing the number of coupling mechanisms or by changing their shape or circumferential spacing. The coupling mechanisms allow the support tube to transmit axial and torsional loads and minimize tube expansion under tension without the use of spines. Alternatively, one or more spines can be formed in the support tube by interrupting the slots at multiple points along the outer circumference and then aligning or offsetting the interrupted portions to form continuous or discontinuous spines.

[0020] In another embodiment, the support tube of the catheter body may have a substantially cylindrical braided pattern formed by multiple strands centered on a longitudinal axis. The cylindrical braid of the strands can define the lumen of the support tube. One or more spines may extend longitudinally along the braided pattern between their proximal and distal ends, and a polymer cover may be positioned around at least a portion of the braided pattern. The polymer cover can enclose at least a portion of the braided pattern and fill the gaps in the braid.

[0021] At least one of one or more spines can be woven into the strands of the braided pattern. Designs with spines woven into the braid can suppress the structure from stretching under tension or shortening under compression. The spines can improve flexural flexibility by having a width that varies between the proximal and distal ends of the braided pattern.

[0022] In a braided pattern, an angle is formed at the point where two strands intersect within the fabric. This angle formed by the strands can be used to adjust the 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 is in the range of approximately 20 to 90°.

[0023] A method for constructing a thrombectomy catheter is also provided. The method may include the step of defining the tubular support of the catheter by arranging a plurality of ribs along its length. The ribs may be circular or of some other shape and may be arranged in a predetermined orientation around the longitudinal axis of the tubular support. The ribs may also be arranged at an angle not perpendicular to the axis, thereby allowing the ribs to move when the forces of the thrombectomy surgery are applied. When the thrombus is drawn into the distal opening of the catheter, the compressive force is transmitted to the ribs, causing at least a portion of the ribs to move proximal to the longitudinal axis, thereby 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 a tubular support, and multiple ribs can be connected at joints to transmit thrust through the tubular support. In one embodiment, one or more spines can be formed integrally with the ribs of the support, such as a laser-cut hypotube. One or more spines may be linear and parallel to the longitudinal axis, or they may be formed spirally or helically around the axis. A radially expandable tip can be connected to the distal end of the tubular support or formed integrally with the distal end of the tubular support. A further step may include placing a polymer cover around the tubular support and at least a portion of the expandable tip. The cover may be elastic so as the tip expands, or it may be bag-shaped or loosely sized around the framework so that the entire radial force of the tip is transmitted to the vessel wall.

[0025] Another step may include forming and arranging ribs and spines to adjust the bending stiffness of the catheter tubular support at different points along its length. The ribs may be, for example, more closely spaced at the proximal end or have a thicker strut width. Similarly, one or more spines may have a width that increases proximal, tapering distally to a narrower profile to provide good indentation and the greater distal flexibility required for access.

[0026] The flexural rigidity can be adjusted by any one or a combination of a change in cutting width and a change in rib width. When the cutting width is kept constant, the flexural rigidity can be adjusted, for example, by changing the width of a laser beam, the rib width and / or the spine(s) width. When the cutting width is changed, the rib width may be kept constant or changed, and a laser can be used to remove pieces of material. It is understood that by using a cutting width equal to the cutting width of a laser beam, no material pieces are removed, and manufacturing costs are significantly reduced. In contrast, by using a laser to remove material pieces, greater variations in shaft design can be obtained. It will also be appreciated that a combination of both approaches can be used, such that the shaft incorporates a more cost-effective cutting / machining means at the proximal end, while the more expensive approach is maintained at a specific distance along the distal end where more complex cuts may be required to obtain the desired performance. For example, the distal end can comprise a 20 cm length portion having cuts that remove material pieces and also include cuts in an expandable tip. In another embodiment, the proximal portion of the shaft is cut from stainless steel (SS) and connected to a distal portion cut from nitinol (NiTi), which reduces the overall cost, while increasing elasticity for sharply curved sections, and can further provide the advantages of NiTi to the distal end of the device where expansion characteristics and recovery characteristics are required. In such a device, the portions of SS and NiTi can be joined to each other either by direct welding or by welding to an intermediate metal more suitable for welding such as platinum. Alternatively, both cut tubes can be held together longitudinally by a laser-cut connection mechanism. The tubes can be held together radially by an outer membrane cover or jacket.

[0027] Other aspects and features of the present disclosure will be apparent to those skilled in the art from consideration of the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and further aspects of the present invention will be further considered with reference to the following description taken in conjunction with the accompanying drawings. The drawings are not necessarily to scale, and instead, emphasis is placed on illustrating the principles of the present invention. The figures depict one or more implementations of the device of the present invention by way of illustration only and not by way of limitation. [Figure 1] It is an isometric view of a thrombus retrieval catheter having a tubular support and an expandable distal tip according to an aspect of the present invention. [Figure 2] It shows an isometric view of a tubular support having a circular rib and two axial spines according to an aspect of the present invention. [Figure 3a] It is a series of views of a support tube according to an aspect of the present invention. [Figure 3b] It is a series of views of a support tube according to an aspect of the present invention. [Figure 3c] It is a series of views of a support tube according to an aspect of the present invention. [Figure 3d] It is a series of views of a support tube according to an aspect of the present invention. [Figure 4a] It is a series of views of another support tube according to an aspect of the present invention. [Figure 4b] It is a series of views of another support tube according to an aspect of the present invention. [Figure 4c] It is a series of views of another support tube according to an aspect of the present invention. [Figure 4d] It is a series of views of another support tube according to an aspect of the present invention. [Figure 5a] It is another support tube having a helical rib according to an aspect of the present invention. [Figure 5b] It is another support tube having a variable rib pitch according to an aspect of the present invention. [Figure 6a] It is a series of views of another support tube according to an aspect of the present invention. [Figure 6b] It is a series of views of another support tube according to an aspect of the present invention. [Figure 6c] It is a series of views of another support tube according to an aspect of the present invention. [Figure 6d] It is a series of views of another support tube according to an aspect of the present invention. [Figure 7a]This is a series of diagrams of another support tube having a helical spine according to an aspect of the present invention. [Figure 7b] This is a series of diagrams of another support tube having a helical spine according to an aspect of the present invention. [Figure 7c] This is a series of diagrams of another support tube having a helical spine according to an aspect of the present invention. [Figure 7d] This is a series of diagrams of another support tube having a helical spine according to an aspect of the present invention. [Figure 8a] A series of figures of another support tube having two helical spines according to an aspect of the present invention, [Figure 8b] A series of figures of another support tube having two helical spines according to an aspect of the present invention, [Figure 8c] A series of figures of another support tube having two helical spines according to an aspect of the present invention, [Figure 8d] A series of figures of another support tube having two helical spines according to an aspect of the present invention, [Figure 8e] This is a diagram illustrating a strain-relieving notch in a support pipe according to an embodiment of the present invention. [Figure 9a] A series of figures of another support tube having radial slots according to an aspect of the present invention, [Figure 9b] A series of figures of another support tube having radial slots according to an aspect of the present invention, [Figure 9c] A series of figures of another support tube having radial slots according to an aspect of the present invention, [Figure 9d] A series of figures of another support tube having radial slots according to an aspect of the present invention, [Figure 9e] This is a diagram illustrating the cuts per revolution of the radial slot of the support tube according to an embodiment of the present invention. [Figure 10a] Two figures of another support tube having radial T-slots for strain relief, according to an aspect of the present invention. [Figure 10b] Two figures of another support tube having radial T-slots for strain relief, according to an aspect of the present invention. [Figure 11a]This is a flat pattern of an exemplary support tube having T-slots and outer-shaping ribs according to an aspect of the present invention. [Figure 11b] This is a flat pattern of another exemplary support tube having T-slots and shaping ribs according to an aspect of the present invention. [Figure 12a] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 12b] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 12c] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 12d] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 13a] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 13b] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 13c] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 13d] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 14] This is the expanded distal tip of a catheter connected to the support tube shown in Figure 13a, according to an aspect of the present invention. [Figure 15a] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 15b] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 15c] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 15d] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 16] This is the expanded distal tip of a catheter connected to a support tube, as shown in Figure 15a, according to an aspect of the present invention. [Figure 17a] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 17b] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 17c] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 17d] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 18a] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 18b] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 18c] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 18d] This is a series of diagrams showing another support pipe according to an aspect of the present invention. [Figure 19a] Various possible strain-relieving notches according to aspects of the present invention. [Figure 19b] Various possible strain-relieving notches according to aspects of the present invention. [Figure 19c] Various possible strain-relieving notches according to aspects of the present invention. [Figure 20a] A support pipe having multiple ribs sharing a spine connection portion, according to an aspect of the present invention. [Figure 20b] An alternative support pipe having multiple ribs sharing a spine connection portion, according to an aspect of the present invention. [Figure 20c] Another support tube according to an aspect of the present invention, having multiple ribs that share spine connections with multiple spines. [Figure 21a] A puzzle-shaped notched support tube having rings connected by a connecting mechanism, according to an aspect of the present invention. [Figure 21b] This is an enlarged view of the support pipe mechanism shown in Figure 21a, according to an embodiment of the present invention. [Figure 21c] Another puzzle-shaped notched support tube according to an aspect of the present invention, having a connecting mechanism and a ring connected by a single spine. [Figure 21d] This is an enlarged view of the support pipe mechanism shown in Figure 21c, according to an embodiment of the present invention. [Figure 21e] Another puzzle-shaped notched support tube according to an aspect of the present invention, having a connecting mechanism and a ring connected by two spines. [Figure 21f] This is an enlarged view of the support pipe mechanism shown in Figure 21e, according to an embodiment of the present invention. [Figure 22a] This is a diagram of a braided support pipe according to an aspect of the present invention. [Figure 22b] This is a diagram of a braided support pipe according to an aspect of the present invention. [Figure 23] This is a flowchart illustrating an overview of how to use the system according to an aspect of the present invention. [Figure 24] This is a flowchart illustrating an overview of how to use the system according to an aspect of the present invention. [Modes for carrying out the invention]

[0029] The objective of the disclosed design is to create a thrombectomy catheter having a radially expandable distal tip for restricting / stopping local blood flow and a tuned, highly flexible body portion that can traverse tortuous regions of vascular structures to reach occlusive thrombi. Such advantages may also be particularly beneficial in stroke interventions, as the vessels within the neurovascular bed are narrow and highly tortuous, and the carefully designed axial and flexural stiffness profiles can prevent twisting and bonding. The catheter is also compatible with relatively low-profile access sheaths and catheters, thus allowing for easy and reliable closure of the puncture wound in the patient's groin (in the case of femoral access). The support structure may also comprise an internal and / or external low-friction liner, as well as an external polymer jacket or membrane positioned around the support structure.

[0030] An advantage of using an expandable thrombectomy catheter with an outer catheter is that, if both are flexible enough to reach the target, the thrombectomy catheter can be retracted along with the thrombus through the outer catheter, thus maintaining access to the therapeutic site by leaving the outer catheter in place. While it is recognized that in some cases it may be necessary to retract the outer catheter along with the thrombus and the inner thrombectomy catheter with certain thrombi, most thrombi are likely to be removed through the inner thrombectomy catheter. Furthermore, the increased certainty that there will be no fragments in the lumen of the outer catheter reduces the risk during contrast agent injection of potential thrombus residue detaching from the catheter during contrast agent injection, as is the case when using a standard intermediate catheter. To address this detachment, the user can remove the intermediate catheter before contrast agent injection and flush out all thrombus residue outside the body, at the cost of losing access to the target therapeutic site. In contrast, this design provides an additional means to minimize the number of catheter advances required to treat the patient, thereby reducing the possibility of vascular damage and the associated risk of vascular transection when multiple passages are required.

[0031] While these descriptions often relate to mechanical thrombectomy, this system and method can be similarly adapted to other procedures and other bodily pathways.

[0032] Herein, specific embodiments of the present invention will be described in detail with reference to the drawings, where the same reference numerals indicate functionally similar or identical elements. Accessing various 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 angiography materials, rotating hemostatic valves, and guidewires, are widely used in laboratory 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 functions and exact configurations will not be described in detail.

[0033] Referring to the figure, Figure 1 shows a thrombectomy catheter 35 used to retrieve a thrombus or occlusion from a patient's blood vessel. The thrombectomy catheter 35 may have an elongated proximal catheter shaft 30, or guidewire, for manipulating and delivering the catheter; a support tube 100 that forms the catheter body extending between the proximal end 112 and the distal end 114; and an expandable tip 42 at the distal end of the retrieval catheter. The expandable tip 42 may be sized and configured such that, when deployed at the target site, it expands radially to make non-traumatic contact with the inner wall of the blood vessel, restricting / stopping blood flow to prevent undesirable aspiration of blood near the tip, and providing a large opening for aspirating and receiving the thrombus.

[0034] The flexibility of the catheter 35 allows the physician to quickly create a pathway to the vicinity of the embolus and gain access using a smaller diameter standard sheath or an external access catheter (not shown). The aspiration catheter can be of the rapid-exchange (RX) type, similar to that shown in Figure 1, with a proximal guidewire 30 connected to a proximal joint 40 of a support tube 100 that defines the catheter body. The support tube may have a length 113 between its proximal end 112 and distal end 114. Preferably, the expandable tip 42 is expanded at the treatment site so that the expanded tip does not need to be advanced through the vascular structure, thereby allowing the length 113 of the support tube to be relatively short. For thrombi located within the anterior or posterior cerebral artery, the length 113 can be greater than 5 cm to allow extension from the lateral catheter to the proximal surface of the thrombus, but can be less than 40 cm to maximize the volume provided for aspiration of the combined lateral / retrieval catheter while the minimum length remains medial to the distal end of the lateral catheter. The shortened distal length 113 also improves the system's followability and flexibility for accessing the target.

[0035] The transition portion at the proximal joint 40 may be designed to form a seal with an outer sheath or intermediate catheter supplied together with the thrombectomy catheter 35 or separately. The seal allows a suction source connected to the proximal end of the intermediate catheter to be directly connected to the opening of the expandable tip 42 of the thrombectomy catheter with little to no loss of negative pressure between the suction source and the opening of the thrombectomy catheter.

[0036] The guidewire 30 may be solid, or it may be a composite of multilayer materials 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 have forming elements that interlock with forming elements of the proximal joint 40 of the catheter body support tube 100, so as to constitute a mechanical lock between the guidewire and the support tube. The connection between the guidewire and the support tube can be reinforced using heat shrink, reflow polymer, and / or adhesive.

[0037] The expanded and deployed form of the expandable tip framework 42 at the distal end 114 of the thrombus retrieval catheter 35 can be flared or funnel-shaped. 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 into the aspiration syringe or canister through the catheter. This compression reduces the likelihood of a hard, fibrin-rich thrombus clogging the tubular portion of the thrombus retrieval catheter. If a thrombus does become lodged in the tip opening, the expanded opening protects the thrombus and prevents it from dislodging as suction is maintained and the catheter 35 is drawn into the sheath or outer catheter.

[0038] The funnel-shaped design of the expandable tip in the disclosed embodiment may be a single-piece grid laser-cut directly and integrally with the support tube of the catheter shaft. Alternatively, the grid of the expandable tip may 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 the diameter of a wide range of target vessels, such as the terminal carotid artery (3.2–5.2 mm), the horizontal M1 of the middle cerebral artery (1.6–3.5 mm), and / or the internal carotid artery (ICA, 2.7–7.5 mm). When the catheter is subsequently withdrawn from the M1 portion to the ICA (or another path with a vessel diameter that increases proximal), the expandable tip 42 continues to seal the vessel over a range of vessel diameters. Furthermore, a tip capable of taking on 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 it is not necessary to advance the expanded tip through the vascular structure.

[0039] The distal portion of the aspiration thrombectomy catheter 110 has good thrust and tracking characteristics to assist in the advancement of the distal portion to the target position. Therefore, the thrombectomy catheter can have multiple designs or be made from multiple materials to give a stiffness profile that decreases along the length in order to minimize insertion and withdrawal forces. In one embodiment, the support tube 100 can be laser-cut from a hypotube and formed integrally with the expanded frame portion of the distal tip 42. In another embodiment, the support tube can be an injection-molded polymer or a metal braid or woven support structure. Furthermore, forming elements that bias bending around a specific plane or promote twisting can be incorporated to reduce the strain applied. This ensures that the catheter maintains excellent lateral flexibility but does not tend to expand or twist under compression.

[0040] The catheter 35 may also have a cover or membrane positioned around or enclosing the support tube 100 and the expandable tip 42. In the embodiments disclosed in the figures of this specification, the jacket or membrane is often not shown in order to make the underlying support structure more visible, but the structure and appearance of such a membrane will be recognizable to those skilled in the art. Suitable jacket materials include elastic polyurethane such as ChronoPrene® or silicone elastomers having a Shore hardness of 40A or less. A single or variable-stiffness cover can be extruded or post-formed over the support tube 100. The cover may also be laminated to the structure or heat-welded.

[0041] Alternatively, the cover may be formed from a series of polymer jackets. By arranging different jackets or sets of jackets at separate lengths along the axis of the support tube 100, different portions of the tubular section of the catheter 35 can be given different indentation and flexibility properties. By configuring the jackets as an axial arrangement, the overall stiffness of the catheter can be transitioned from the proximal end, which has higher stiffness, to the distal end, which has very high flexibility. Alternatively, by arranging the polymer jackets of the cover in a radial arrangement around the support tube, the material properties can be adjusted across the thickness. In further embodiments, tapering or slotting the transitions between jackets can provide a smoother transition between the flexibility profiles of adjacent jackets within the longitudinal arrangement.

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

[0043] The support tube 100 structure of the framework structure 110 of the thrombectomy catheter 35 can have many different configurations. In one embodiment, the support tube 100 can have a structure similar to the structure shown in Figure 2. The tube 100 can have a support framework structure 110 in which one or more axial spines 116 extend 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 have high axial rigidity for advancing and retracting the catheter, which has sufficient lateral flexibility to travel through the blood vessel. Using multiple spines promotes bending along a specified plane, while reducing the possibility of the support tube 100 stretching under tensile load, such as when the expandable tip is retracted into the mouth of the outer catheter. Multiple ribs 118 can be provided along the length of one or more axial spines, which may be axially symmetric with the longitudinal axis 111 of the thrombectomy catheter 35. Each rib 118 can define the central lumen 119. Each rib 118 may have a simple circular shape as shown in the figure, or it may have a more complex shape as needed.

[0044] Each rib 118 and one or more axial spines 116 of the tubular support frame structure 110 can be formed by laser cutting a tubular material such as a hypotube, or from other similar structures including braids, fabrics, and / or strands including coils having overlapping or interwoven spines. This allows the support tube 100 to have good indentation and torque characteristics, torsional resistance, resistance to crushing under suction, and reliable resistance to tensile elongation. Commonly used materials include nitinol and well-known medical-grade stainless steel alloys such as 304 and 316. In hypotubes made of different materials, such as stainless steel for the proximal portion of the tubular support tube and nitinol for the distal portion and expansion opening of the tubular support tube, these different materials are joined by welding, bonding, or by holding interlocking features in place with an inner and / or outer polymer jacket material.

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

[0046] Although one or more spines 116 are shown flush with the ribs 118, it will be understood that the spines may be positioned in the middle of the walls of the supporting frame structure 110 or tangentially to the interior walls.

[0047] Adjusting the stiffness and changes in stiffness of the catheter is important in situations where distance and tortuosity can be significant, such as when the catheter needs to be advanced from the patient's inner thigh through the cardiovascular arch to the intracranial neurovascular region. This stiffness can be adjusted when forming the framework structure 110 by sizing the notches in the hypotube for forming the ribs 118 and spines 116. For example, each rib can be cut to a variety of widths and spacing densities. The notches may be continuous in the circumferential direction, terminate on both sides of the axial spine 116, or be discontinuous in a repeating or non-repeating pattern along the circle of the tubular portion. When discontinuous notches are aligned axially, they can form one or more further axial spines 116 for biasing the bending and flexing plane of the catheter support tube 100. As a further example, when circumferentially discontinuous notches are mixed and aligned with circumferentially continuous notches, they can form discontinuous axial spines.

[0048] One or more portions of the support tube 100 can extend radially outward to form a seal with the inner diameter of the outer or intermediate catheter. In another embodiment, sealing or flow restriction is not required, 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 aspiration loss is negligible. Alternatively, the catheter diameter can be sized so that the lumen is configured to allow aspiration to be applied at two locations: the distal end of the thrombectomy catheter and the distal end of the outer catheter.

[0049] In other embodiments, the tubular shaft of the catheter may be supplied without a strut support structure, and the tubular shaft is formed solely from the polymer portion. For example, catheter 35 may have a shaft formed from a single polymer extruder. The extruder can be manufactured from, for example, polyetheretherketone (PEEK), polyimide, polyethylene, or another robust thermoplastic polymer. A series of raised and recessed areas can be laser-cut into the surface of the extruder to impart a profile, thereby providing enhanced torque, indentation, and conformability. The raised or recessed areas can be applied by passing the polymer extruder through a heated profiling die that melts and cools the tube as the polymer extruder passes through. A homogeneous support structure can be provided as desired by using a composite tube that has been reflowed to have a pre-variable longitudinal stiffness profile prior to profiling, and then passed through a profiling die.

[0050] Where the outer jacket covers the laser-cut hypotube and is reflowed into the space between each rib 118, material may protrude radially at the location of the laser-cut strut. By then pulling the shaft through the sizing die, all excess material above the strut can be removed, resulting in a consistent overall outer diameter of the shaft of the support tube 100 and a smaller delivery profile.

[0051] One or more axial spines 116 themselves can be formed or cut to varying thicknesses. Thicker spines can provide higher columnar strength and axial rigidity, improving catheter torsional resistance, insertion performance, and withdrawal performance. Conversely, thinner spines can provide greater flexibility in bending to follow the meandering regions of the vascular structure. One or more spines can also be tapered in thickness along their axial length to incorporate both of these advantages. One or more tapered spines can be made more rigid proximally to provide good indentation characteristics and highly flexible distally so that the tubular portion can twist and bend around the vascular pathway.

[0052] Figures 3a to 3d show a tube of an exemplary support tube frame structure 110 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 be varied over the entire length of the tube frame structure 110. The spine may have at least a first width or thickness 136 distal to it, which is smaller than a second width 138 proximal to it, as shown in Figure 3c. The proximal thickness of the spine 116 may be thicker than that of the more distal portion of the support tube, providing greater rigidity and better indentation, while the distal portion of the frame structure 110 may have a thinner, more flexible spine 116 so that the frame structure can twist and turn along a meandering vascular pathway.

[0053] By using at least one spine 116 as shown in Figure 3b, the possibility of elongation under tensile load can be reduced, such as when the distal tip 42 of the enlarged catheter is drawn into the outer sheath or intermediate catheter. Each rib 118 of the frame structure 110 can terminate at opposite joints 126 on either side of the tapered spine 116. Each rib 118 can have varying strut widths and varying spacing densities between adjacent ribs in order to further optimize the rigidity profile of the support tube 100.

[0054] Another example of a support tube frame structure 110 having two tapered spines 116 separated by 180° is shown in Figures 4a to 4d. Similar to Figure 3, each spine may be tapered at various different angles along their 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. Generally, the support tube 100 can be made more rigid 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 occlusion.

[0055] Compared to a single spine, the use of additional spines 116 can provide the frame structure 110 with greater resistance to localized elongation between the ribs 118 when the support tube 100 is subjected to lateral and tensile loads. The arrangement of the tube's spines 116 opposite each other (see Figure 4b) can facilitate the bending of the frame structure 110 within a single plane 120 extending through the two spines (see Figure 4a). Combining this configuration with a pair 126 of oppositely positioned joints of the ribs 118 can help transmit a balanced, consistent compressive or thrust force throughout the length of the catheter. Multiple spines also help the support frame structure resist longitudinal compression during deployment, ensuring precise placement at the treatment site. The arrangement of spines positioned opposite each other also prevents the frame structure 110 from bending either spine in a direction perpendicular to the circumferential direction of the spine, which is a direction in which twisting or potentially fracture is likely to occur where the strut width of the spine exceeds its thickness.

[0056] Figures 5a and 5b show a support tube 100 in which each rib 118 of the support frame structure 110 is arranged in a coiled, helical shape around the longitudinal axis 111 of the support tube 100. The coiled structure can be manufactured to have overlapping spines 116 as shown in Figure 5a, or the structure can be integrally formed by laser cutting the ribs and spines into a single hypo tube. In a similar example, the two spines 116 can be formed 180 degrees apart along the length of the coil, as shown in Figure 5b. The helical shape of the rib 118 with two spines may mean that the respective joint points 126 of the rib with each spine are axially offset on both sides of the support frame 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 imparting stiffness to a particular region of the tube, while increasing the rib pitch and / or reducing the rib width can reduce the stiffness of a given portion. For example, the distal portion of the catheter can be given greater flexibility by making the thickness 141 of the more proximal rib greater than the thickness 142 of the more distal rib, or by making the pitch 139 of the proximal rib smaller than the pitch 140 of the distal rib. Similarly, the same effect can be achieved by making the width 138 of the more proximal spine greater than the width 136 of the more distal spine.

[0058] By optimizing the combination of the parameters of the support frame structure 110 of the ribs 118 and spines 118 and the hardness and / or thickness variations of the outer jacket or membrane material, the catheter body can be given effective pushability, conformability, and torque transmission in different regions of the support tube 100, thereby enabling the catheter to be delivered along the most difficult vascular pathways and reach distant target therapeutic locations.

[0059] Referring to Figures 6a-d, the support tube 200 may have a frame structure 110 having two intermittent spines 214 that extend parallel to the longitudinal axis 111 of the tube, with adjacent straight portions of each spine spaced 90° apart. This configuration can be formed by cutting a series of rounded radial slots 212 into alternating opposing sides of a hypo tube or other tubing material to form adjacent ribs 118 along the length of the support tube 200. This design effectively has intermittent spines at 90, 180, 270, and 360° positions around the frame structure 110, thereby allowing the tube to bend within two vertical bending planes 120, 121 that are axially aligned and extend through each of the intermittent spines 214.

[0060] Having intermittent spines that define multiple bending planes allows for greater degrees of freedom of movement within the three-dimensional vascular pathway. However, such a design results in lower column stiffness, making it more susceptible to axial stretching under tension, such as when the expandable opening of the catheter is retracted into the outer intermediate catheter. The expansion of the support tube may prevent the opening from collapsing against the captured thrombus, thus preventing it from applying a more effective gripping force to the captured 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, the hypotube support frame structure 110 and the wire spines can be fused together using an outer polymer jacket or membrane. The wire spines can add structural integrity under tensile load and prevent the tube from stretching axially when the catheter tip 42 with an expanded opening is drawn into the outer sheath of the intermediate catheter. In another embodiment, the stiffness can be adjusted in such a way that the width of the struts of the rib 118 is increased to prevent undesirable stretching of the support tube 200.

[0062] Referring to Figures 7a-d, the support tube 100 may have a frame structure 110 having loop-shaped ribs 118 connected by helical spines 117 extending between the proximal end 112 and distal end 114 of the frame structure. A similar design in which two helical spines 117 extend 180° apart from each other with a phase difference is shown in Figures 8a-d. The helical spines allow the support tube 100 to twist along the length of the tube about the longitudinal axis 111.

[0063] Similar to intermittent spines, spiral spines also tend to straighten and elongate when tension is applied to the support tube 100. To prevent elongation, the spiral pitch can be increased so that the twist is very gentle and one or more spines locally become nearly straight. For example, a pitch of 10 mm to 200 mm, more preferably 50 mm to 100 mm, can be used.

[0064] The composite design may have a support frame structure 110 in which one or more helical spines 117 are fused with a portion of the frame structure in which one or more spines are straight with respect to the axis 111. The possibility of tensile elongation can be reduced by aligning the region of the support tube 100 having a more flexible outer cover or jacket (not shown) with the straight spines.

[0065] If the helical spine 117 may have joints 126 that form an acute angle with each rib 118, a notch 128 with a large edge radius can be formed, as shown in Figure 8e. The notch 128 can locally alleviate the strain at the joints 126 when the support frame structure 110 twists about the longitudinal axis 111.

[0066] Various diagrams of other embodiments of the support tube 300 are shown in Figures 9a to 9e. The support tube 300 may have a substantially tubular portion, such as a hypotube or polymer extruded, having a pattern of notches that form spaced radial slots 312 around a longitudinal axis 111. The interrupted portion may be arranged such that discontinuous portions of the notches axially align to form one or more continuous spines 314. In one embodiment, the radial slots 312 form two continuous axial spines 314 separated by 180° to maintain a smooth rigidity profile on the alternating sides of the support tube 300.

[0067] In one embodiment, the notches forming the radial slots 312 can be provided around the entire circumference of the support tube 300. By incorporating geometric elements that form keyed boundaries that interlock with adjacent axial portions along the circumference of the tube, longitudinal and torsional loads can be transmitted without the use of a spine. The keyed boundaries can be dovetail-shaped or similar in configuration so that the support tube bodies fit together like puzzle pieces. In a similar embodiment, a key joint can be maintained, but by cutting out the radial slots 312 to have discontinuous portions, a continuous or discontinuous spine can be formed to suit situations where further indentation is desired.

[0068] In some cases, as seen in Figures 9b and 9c, the radial slots 312 can be spiral in shape and include alternating interruptions in the pattern, thereby forming one or more intermittent spines 315 that are angularly offset from one or more continuous spines 314. Thus, the spiral notch pattern can have one or more radial notches per revolution 316 around the longitudinal axis 111. In the embodiment shown in Figure 9e, three notches per revolution are used. Each notch or radial slot 312 may be cut to a fixed length, or varying lengths may be used to provide lateral flexibility of the support tube 300 in multiple planes. By determining the pattern of the radial slots 312 to incorporate both continuous spines 314 and intermittent spines 315, the possibility of the support tube 300 stretching under tension can be minimized.

[0069] Figures 10a and 10b show another support tube 300 using a hypotube or polymer extruded material with radial slots 312 cut into the tubular portion. Each cut can be planar with a transverse axis on the alternating sides of the support tube 300. Each cut of the radial slot 312 can terminate or transition into transverse cuts to form an "I" or "T" shaped pattern defining one or more continuous axial spines 314. The transverse cuts in the pattern can function as strain-relieving notch 128 mechanisms, which 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 be arranged alternately in an offset pattern on both sides of the spine to form two continuous spines separated by 180°. The two continuous spines allow the support tube 300 to maintain considerable longitudinal stiffness along the axis 111.

[0070] Flat patterns showing modified support tubes 300 having T-slots 317 and strain-relieving notches 128 are shown in Figures 11a and 11b. Each T-slot 317 can be cut at angles or curves as shown in the figures, such that the formed member becomes a contouring rib 320 whose thickness varies around the longitudinal axis 111 of the tube. As seen in Figure 11a, the contouring rib 320 can be wider near opposing continuous spines 314 and narrower in the intermediate section between the spines. This configuration provides greater space for the rib 320 to move in a bent state, while also providing further support for the tube 300 against vacuum pressure under suction.

[0071] In another embodiment, the strain-relieving notch 128 of the rib 320 may be a T-slot 317 having a gentle curve or radius in the spine 314, as shown in Figure 11b. The curved T-slot can give the support tube 300 further flexibility by promoting tangential bending of the curve, while providing additional space for the shaping rib 320 to bend proximal or distal to each other within the tortuous vessel.

[0072] Figures 12a-d show another example of a support tube 100 which may have a tubular frame structure 110 in which a single axial spine 116 fixes a plurality 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 smaller than the proximal second width 138, thereby giving the frame structure 110 good proximal indentation and a more distally flexible spine for twisting and torsion through the vascular pathway.

[0073] Each rib 118 can be cut out at an angle 130 such that each free end extends distally to the junction 126 between the spine 116 and the rib. Although the ribs 118 are angled, they can maintain a circular inner lumen 119 (as shown in Figure 12d) and outer diameter. This configuration allows each rib 118 to move proximal to the spine 116 when compressed between each junction 126 and a rigid thrombus that resists being stretched into the nominal stationary inner diameter of the frame structure 110. This compressive force transmitted to the most distal rib can be transmitted proximal to adjacent ribs by an outer cover and / or jacket (not shown) positioned around or enclosing the frame structure. The jacket can be reflowed against the cut-out support frame structure 110 so that it is positioned between adjacent ribs 118 and transmits longitudinal loads between adjacent ribs 118. The jacket may be made of polymer, giving it elasticity such that it stretches and expands in diameter in response to the movement of the ribs. The compressive force from the thrombus increases the cross-sectional area of ​​the lumen 119 as the ribs move proximal to a position where the angle 130 of the ribs becomes more perpendicular to the spine 116 and the longitudinal axis 111, and the elastic jacket expands radially outward. This temporarily increases the receptive space available for capturing the thrombus.

[0074] Figures 13a to 13d show an exemplary embodiment of a method for further adjusting a support tube 100 similar to those in Figures 12a to d to further optimize its delivery characteristics. The variable-width spine 116 can connect the variable-rigidity portions of the support tube, where the proximal rib pitch 139 of the ribs 118 in the more proximal axial portion is greater than the distal rib pitch 140 of the more distal axial portion. The spine 116 may 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 frame structure 110, thereby increasing the distance between the respective joint points 126 between the spine and each rib 118. It will be understood that the spine can be tapered to other intermediate widths between the first and second widths. The ribs themselves can also be cut to different thicknesses in different axial portions of the support frame structure 110 as desired, or formed to different thicknesses at different clock positions around the longitudinal axis 111.

[0075] Figure 14 shows a support tube 100, similar to the embodiment in Figure 13a, connected at its distal end 114 to the framework structure of the self-expanding catheter tip 42. The struts of this framework structure can be formed from nitinol or another shape-memory material having sufficient elastic strain performance so as not to exceed the elastic limit when the tip is delivered in a collapsed form within the outer catheter. Further framework structures made of wire or non-superelastic material can also be envisioned, which require less strain to move from the folded state for delivery to the expanded state for thrombus retrieval.

[0076] The spine 116 of the support frame structure 110 can transition directly to one or more struts of the spine extension 44 at the distal end 114, and integrating the spine with the extension (e.g., cutting from the same hypotube) results in a smoother catheter rigidity profile and eliminates weaker transition areas. The support arms 45 of the expandable tip 42 may extend distally from the central junction with the spine extension 44, or one or more arms may be connected to the most distal rib of the support frame structure 110. Each arm can form the outer circumference of the enlarged distal opening 46 of the catheter tip 42 by connecting to other struts or by including radially curved sections. The support arms 45 may be configured to expand radially outward when a thrombus is aspirated, or when a thrombectomy device is drawn through the opening 46 to increase the success rate, for example, when targeting a rigid thrombus.

[0077] Each support rib 118 of the support tube 100 can be formed at an angle to the axis of the tube such that each rib has a substantially cylindrical profile but no planar cross-section. If each support arm 45 of the tip 42 is not directly connected to the most distal rib, the free end of each rib 118 can move proximal to the longitudinal spine 116 under compressive loads, such as when drawing in a thrombus. The proximal movement of each rib 118 may have the effect of locally expanding the inner diameter of the catheter lumen 119 when a thrombus is drawn in through the support tube. The elastomer outer jacket or membrane covering the support frame structure 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] Figures 15a to d show an embodiment of a support tube 100 having a tubular support frame structure 110 in which axially curved ribs 118 are spaced apart between two continuous spines 116 separated by 180°. Each rib 118 may have a proximal peak 136 that defines the nearest point where the rib intersects the spine 116 at each joint 126. The profile of the rib 118 beyond the joint 126 may have one or more curves, but may still have a gently undulating non-planar cross-section that defines a substantially cylindrical catheter lumen 119. As shown in isometric view in Figure 15a, the profile of the rib may have a first proximal curve 132 offset radially from the proximal peak 136, and a second distal curve 134 offset radially from the proximal curve and reaching its peak at the distal peak 138, so that at least a portion of the rib is distal to the connection at the joint 126. It can also be understood that the corresponding junction points 126 with each spine 116 may be axially offset proximal or distal to the junction point on the opposite side of the other spine. The ribs 118, which form a nearly cylindrical profile but do not have a planar cross-section, have the ability to expand under compression when a thrombus is pulled from the blood vessel into the inner lumen 119 of the catheter, thereby allowing this form of the supporting framework structure 110 to "swallow" dense thrombi that would otherwise be restricted to entering a non-expandable form.

[0079] A support frame structure 110 having one or more axially curved ribs 118 can be configured, as shown in Figure 16, to have a spine 116 that is connected collinearly to the support arm 45 of the frame structure of the dilating catheter tip 42 at its distal end 114. The collinear connection of the arm 45 and the spine 116 allows the forward force to be directly transmitted along the spine to the support arm as the catheter is advanced through the outer intermediate catheter, thereby improving pushability. This configuration also allows the distal peaks of each rib 138 to be kept free, so that the frictional and compressive forces generated between the support frame structure 110 and the outer catheter during advancement, caused by the dilating tip being pressed radially outward against the outer catheter, are not transmitted in a direction that would expand the ribs. Otherwise, this expansion could adversely affect delivery by increasing friction, as at least a portion of the support tube 100 would be pressed against the inner surface of the outer catheter.

[0080] Figures 17a to d show a support tube 100 having a support frame structure 110 similar to the support frame structure 110 in Figures 15a to c, but with ribs 118 extending circumferentially in a wavy pattern. Each rib 118 can intersect two offset spines 116 separated by 180° in a nearly perpendicular manner at each joint 126. Thus, the proximal curved portion 132 and distal curved portion 134 of each rib can form a proximal peak 136 that is circumferentially offset from each spine 116. Each rib can bend individually because the distal peak 138 of each rib can be kept free. This wavy pattern creates more contact points between the rib 118 and the outer jacket or membrane, distributing the force more uniformly around the entire circumference, while still maintaining the ability to expand under compression. It will also be understood that the strut width of the ribs and spines can be varied, and that the motion of the ribs 118 and the stiffness profile of the support frame structure 110 can be further adjusted by offsetting the corresponding connection points axially in each spine.

[0081] Figures 18a-d show an example in which the ribs 118 of the support frame structure 110 may have a proximal curved portion 132 and a distal curved portion 134 that curve in the opposite direction to the ribs in Figures 17a-d. Because the corrugated shape of the ribs of the support tube allows the tube to expand, rigid thrombi that cannot be pushed into the nominal stationary inner diameter of the device can instead be recovered by radial expansion of the support frame structure 110, which may occur when aspiration is maintained against a blocked or incompressible thrombi. As in other embodiments, the outer jacket or membrane covering the support frame structure 110 may be formed of an elastomer material so as not to restrict the expansion of the support tube. The use of two spines 116 in embodiments in which the ribs have a circumferential corrugated or wavy pattern provides better pushability than a single spine, while preventing the support tube 100 from stretching under tension as the expandable tip 42 is drawn proximal into the outer intermediate catheter.

[0082] Further mechanisms to enhance the movement of the ribs 118 and the overall flexibility of the supporting frame structure 110 include enlarged openings or notches 128 at each joint 126 of the frame structure. The notches 128 increase the mobility of individual ribs relative to one or more spines 116 while providing interface strain relief. A highly flexible catheter can reduce the risk of cracking or eventual failure by reducing geometric stress concentration at each joint through the strain-relieving notches 128. The notches 128 at each joint 126 allow the treatment load to be absorbed more effectively by encouraging each rib to bend independently.

[0083] Various further geometric shapes of strain-relieving notch patterns can be seen in Figures 19a and 19c. These mechanisms can be introduced into the support tube 100, which is a hypotube, by incorporating an additional processing step into the rib cutouts, or they can be cut or integrally formed when the support tube is extruded or injection molded. Depending on the preference for flexibility in a particular axial portion of the tube support frame structure 110, the user can introduce chamfered or rounded strain-relieving notches 128 at the corners of each joint 126, as shown in Figure 19a. Such notches can be particularly useful in situations where the rib space 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 joint 126 with an extended, larger radius, as shown in Figure 19b. Similarly, fine rib spacing can be maintained by providing smaller relaxation notches 128 at the corners of the joint 126, as shown in Figure 19c.

[0084] To improve the multiaxial flexibility of a support tube, it is often advantageous to minimize the total number of connections to one or more spines. Figures 20a-c show several embodiments in which a support tube 100 has a support frame structure 110 in which a series of support ribs 118 converge into a single spine connector 146 and connect to one or more spines. Each set of support ribs may contain one, two, three, or more ribs 118. In Figure 20a, a pair of ribs 118 have opposite-positioned wing-shaped portions 147 that curve or taper towards the center toward the spine connector 146 that connects to the spine 146. By connecting multiple support ribs 118 as sets with a single connection to one or more spines 116, longer portions of the spine can bend freely relative to a given density of ribs. A similar concept using three ribs 118 connected to a single connection is shown in Figure 20b. The outer ribs of this set may have wing-shaped portions 147 for joining a central rib which may have a direct connection to the spine connector 146.

[0085] As shown in Figure 20c, a series of support ribs 118 can converge at opposite spine connectors 146 to connect to two spines 116 separated by 180°. Further spines may also be considered. Two opposite spines can provide better indentation than a single spine, while preventing the support tube 100 from stretching under tension, such as when the expandable tip 42 is retracted proximal into the outer catheter. Fewer connections to spines can give the frame structure 110 better flexibility to bend along the bending planes passing through the longitudinal axis 111 and the spines 116, respectively.

[0086] Further embodiments of the support tube 400 having different configurations in which radial slots form a puzzle-like notch pattern are shown in Figure 21a. The puzzle-like notch tube can substantially be a series of connecting ribs or rings 403. Since each ring 403 is not integral with any adjacent ring, either proximal or distal, the puzzle-like notch tube can twist about the longitudinal axis 111. The structure of the puzzle-like notch support tube 500 can also resist tensile elongation by the interlocking of adjacent connecting mechanisms 404, 405. The distal connecting mechanism 405 can interlock a particular ring with the next distal ring, and the proximal connecting mechanism 404 can interlock with the next proximal ring.

[0087] The flexibility of the puzzle-shaped notched support tube 400 can be varied by increasing or decreasing the size of the connecting elements 406 between the connecting mechanisms of each ring 403. Figure 21b shows how flexibility can also be varied by changing the number, shape, and / or spacing of the connecting mechanisms 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 lengthened by the sum of the longitudinally distributed spacings 408. Similarly, the acceptable torsion can be adjusted by changing the circumferential spacing 410. The torsional characteristics provided by the puzzle-shaped notch design of the support tube assist in the bending and torque transmission of the catheter in multiple planes as the support tube is advanced through a meandering vascular pathway.

[0088] Figures 21c and 21d show how the support tube 400 can have a puzzle-cut design with a connecting mechanism, while incorporating a longitudinal spine 416. As seen in Figure 21d, the spine 416 can be added by aligning the interrupted portions of the radial slots of the puzzle-like cuts, thereby fixing each ring 403 longitudinally at the spine. It will be understood that each portion of the spine 416 may be offset circumferentially, or the thickness of the spine may vary at different axial positions along the length of the support tube 400. Adding the longitudinal spine 416 helps prevent the puzzle-like cut tube from stretching under tensile load. Furthermore, the effect of a single spine on the twisting ability of the puzzle rings 403 is minimal, so the catheter support tube can maintain its conformability advantage.

[0089] Referring to Figures 21e and 21f, the puzzle-shaped notched support tube 400 may have two longitudinal spines 416 separated by 180°. The addition of the two spines 416 prevents the support tube from stretching under tensile load and provides the tube with a preferred bending plane. When the two spines separated by 180° are aligned parallel to the longitudinal axis 111 as shown in the figure, the effect of the puzzle ring on the ability to twist is minimal, and the twist changes the preferred bending position of the tube to the extent that it is controlled by the design twist, thereby allowing the support tube to self-adjust as it is advanced through the meandering vessel.

[0090] In another embodiment, as shown in Figure 22a, the support tube 500 may have a metal and / or polymer strand or wire structure formed as a braided or coiled structure 510. The strands 511 of the braided pattern 510 form a continuous radial arrangement, which is roughly equivalent to a single main support member and can be dense enough to support the outer membrane, similar to a laser-cut hypotube. Each strand 511 of the support tube 500 may be formed on a straight mandrel such that one or more portions of the tube flares outward radially to form a seal with the inner diameter of the outer or intermediate catheter.

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

[0092] This extension can be achieved by changing the size, orientation, or other characteristics of each strand 511 of the pattern 510. Further flexibility can be obtained by changing the braid angle 512 or the picks per inch (PPI) of the pattern. The braid angle 512 and pattern density of the strands 511 can be selected to match the preferred axial and transverse mechanical properties of a given portion of the support tube 500. For example, the braid angle and / or PPI may differ in the more proximal portion of the support tube, thereby giving the proximal portion better indentation 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 the freedom to compress in the longitudinal direction. Since the wires or strands of a 20° braid are more spread out in the longitudinal direction, maintaining a braid angle close to 90° provides the frame structure with greater flexibility than a braid angle close to 20°. A braid angle 512 greater than 90° can also be expanded, but the degree of expansion will be less due to the denser spacing between the braid strands 511.

[0094] As in other embodiments, the braided pattern 510 may have an elastomer outer cover or jacket (not shown). The jacket may be reflowed onto the outer surface of the braided tube or formed to enclose the strands 511. The reflowed jacket material fills the gaps between the braided pattern 510 and the spines 516, further reducing the expandability or contractility of the tube. Enclosing the pattern 510 with a reflowed polymer jacket may also help to hold the braid and spines 516 together. The jacket may be impermeable, or the braided or coiled pattern 510 may be dense enough to substantially obstruct fluid flow between the outside and inside of the support tube, thereby eliminating the need for an impermeable cover or seal.

[0095] Any of the support tubes for thrombectomy catheter designs disclosed herein can be used in conjunction with a mechanical thrombectomy device. The combination of mechanical thrombectomy and suction through the funnel-shaped tip can increase the probability of success on the first pass when removing a thrombus. During thrombectomy, the funnel shape of the tip can reduce shearing of the thrombus as it enters the catheter, stopping the flow and protecting the distal vessel from embolus in new areas. Furthermore, the mechanical thrombectomy device can guide the suction vacuum to the thrombus surface while holding the composite thrombus (consisting of a fragile region and a high-fibrin region) as a single unit, thereby preventing embolism and helping to dislodge the thrombus from the vessel wall. The shape of the tip may also help prevent fragmentation if the thrombus enters an offset position at the opening of the catheter.

[0096] The mechanical thrombectomy device can support the lumen of the blood vessel during aspiration to prevent collapse under negative pressure, and holds the thrombus together if it contains many hard and soft parts that could otherwise fragment. The mechanical thrombectomy device also allows the user to grasp any thrombus that does not fully enter the lumen of the thrombus retrieval catheter, thereby preventing the thrombus from detaching from the thrombus retrieval catheter as the thrombus, thrombus, and mechanical thrombectomy device are drawn out of the patient's body through the vascular structure and the outer catheter. The interaction between the outer catheter and the expanded opening helps to gradually compress the thrombus so that it can be drawn through the outer catheter together with the thrombus retrieval catheter and mechanical thrombectomy device. If the thrombus is still too large to enter the outer catheter, the thrombus retrieval catheter and mechanical thrombectomy device can be retracted proximal through the blood vessel into a second, larger diameter outer catheter, such as a balloon guide. If the thrombus remains too hard to be retrieved through the second external catheter, all the devices can be retracted together through the vascular structure and out of the body. The thrombus retrieval catheter can be designed to work with an external catheter such as a long guide sheath or balloon guide sheath of 7Fr, 8Fr, 9Fr, or 10Fr. Alternatively, the thrombus retrieval catheter can be designed to work with an external catheter such as an intermediate catheter of 4Fr, 5Fr, or 6Fr.

[0097] Figures 23 and 24 are flowcharts, respectively, illustrating the steps of a method for manufacturing a thrombectomy catheter having a support tube according to each aspect of the present disclosure. Each step of the method may be performed by any of the exemplary systems, instruments, and / or apparatus described herein, or by means well known to those skilled in the art.

[0098] Referring to method 2300 outlined in Figure 23, step 2310 describes the task of arranging a plurality of ribs along the length, each rib circumferentially oriented around the longitudinal axis to define a substantially tubular support. The ribs can be circular, spiral, or any other suitable shape suitable for endovascular procedures. The ribs can be formed by laser cutting a hypotube, cutting radial slots into an extruded tube, or by other methods commonly known in the art. Step 2320 includes forming or arranging the plurality of ribs such 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 obtained by adjusting various properties of the ribs, such as the spacing between the ribs or the different thicknesses of the rib struts, and by 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 thrombectomy, the angled orientation of the ribs changes the cross-sectional size of the internal catheter lumen, which can facilitate thrombectomy and / or aspiration.

[0099] Step 2340 may include forming one or more spines extending along the length of the tubular support, and may also include attaching each rib of a plurality of ribs to one or more spines. The spines may be mechanically connected to the ribs, or the spines and ribs may be integrally formed by machining the hypotube or cutting radial slots into the extruded tube. By having fixed joints or attachment points with one or more spines, the ribs can be configured to move proximal or distal to one or more spines when different forces act on the tubular support during surgery, as in step 2350. This movement can locally increase the diameter of the tubular support when a thrombus is extracted, or reduce the frictional forces generated when the thrombus retrieval catheter is advanced or retracted through the external catheter. Different configurations of the ribs and spines of the tubular support, such as narrowed rib struts or using a single axial spine to give each rib an unrestrained free end, will be understood to facilitate rib movement.

[0100] Referring to method 2400 outlined in Figure 24, in step 2410, one or more spines of the tubular support are positioned to share the longitudinal axis of the support tube. For example, a linear axial spine may share an axis parallel to the longitudinal axis of the tubular support, or a helical spine arrangement may have a twist concentric with the longitudinal axis of the tubular support. In step 2420, the spines may be cut or formed so that the flexibility of the tubular support changes along the length of the tubular support. By transitioning the width of the spine from a thicker proximal side to a thinner side, good conformability within the blood vessel can be maintained, while providing greater flexibility necessary for accessing the distal portion of the tubular support.

[0101] Further steps for fabricating the tubular support for a thrombectomy catheter are shown in step 2430, which may include fixing or integrally forming a radially expanding tip to the distal end of the tubular support so that the catheter has a large distal-facing opening that can form a seal with a blood vessel and can locally restrict / stop flow when deployed. In step 2440, the tubular support and at least a portion of the expandable tip may be covered with a polymer cover. For example, the cover may be a series of outer jackets reflowed, injection-molded, or laminated onto the radial surfaces of the outer and / or inner ribs. Those skilled in the art will also understand that the coating step may provide the surfaces of the tubular support and / or cover with lubricating, low-friction properties.

[0102] The present invention is not necessarily limited to the examples described, and may vary in configuration and detail. The terms “distal” and “proximal” are used throughout the foregoing description and mean location and direction relative to the treating physician. Thus, “distal” or “distal” refers to a location away from the physician or a direction away from the physician. Similarly, “proximal” or “proximal” refers to a location close to the physician or a direction toward the physician. Furthermore, unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” include multiple referents.

[0103] The terms “about” or “approximately” used herein with respect to any numerical value or range of numerical values ​​indicate a suitable dimensional tolerance that enables a part or set 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 ​​within ±20% of the given value; for example, “about 90%” may refer to a range of values ​​between 71% and 99%.

[0104] In describing exemplary embodiments, technical terms are used for clarity. Each term is intended to have its broadest meaning as understood by those skilled in the art and is intended to include all technical equivalents that operate similarly to achieve similar purposes without departing from the scope and spirit of this disclosure. It should also be understood that reference to one or more steps of a method does not preclude the existence of additional step-by-step methods or step-by-step methods intervening between those explicitly identified steps. Some steps of a method may be performed in an order different from that described herein without departing from the scope of the disclosed art. Similarly, reference to one or more components of an apparatus or system should also be understood as not precluding the existence of additional components or components intervening between those explicitly identified components. For clarity and brevity, not all possible combinations are listed, and such modifications are often obvious to those skilled in the art and are intended to fall within the scope of the following claims.

[0105] [Implementation Method] (1) A tube that forms the main body of the catheter assembly, A tubular support frame 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 that are arranged along the length of one or more spines and extend through the support frame structure, defining the lumen of the support frame structure, A joint point connecting one or more of the plurality of ribs to one or more of the spines, A tube comprising a support frame structure, the support frame structure comprising a polymer cover disposed around at least a portion of the support frame structure. (2) The pipe according to Embodiment 1, wherein at least one of the one or more spines has a proximal spine width different from the distal spine width between the proximal and distal ends of the support frame structure. (3) The pipe according to Embodiment 1, further having a spacing between adjacent ribs that changes between the proximal end and the distal end of the support frame structure. (4) The tube according to Embodiment 1, wherein the ribs are arranged in a spiral shape along the length of one or more spines. (5) The pipe according to Embodiment 2, wherein one or more spines are arranged as helical spines in a spiral shape centered on the longitudinal axis of the support frame structure.

[0106] (6) The pipe according to Embodiment 1, wherein at least one of the plurality of ribs has a first rib width that is different from the second rib width of another rib among the plurality of ribs. (7) The pipe according to Embodiment 1, wherein the ribs are arranged at an angle of less than 90° with respect to the longitudinal axis of the support frame structure. (8) The pipe according to Embodiment 1, wherein the joint includes a notch configured to alleviate the distortion of the support frame structure at the joint. (9) The pipe according to Embodiment 1, wherein the rib has a non-planar cross-section in which the profile of the rib includes one or more curved portions. (10) The pipe according to Embodiment 1, wherein two or more of the plurality of ribs converge into a spine connector having a single connection point with each of the one or more spines.

[0107] (11) A tube that forms the body of the catheter assembly, A tubular support frame structure having a proximal end, a distal end, an internal lumen, and a pattern of radial slots arranged around the longitudinal axis, A tube having a polymer cover disposed around at least a portion of the support frame structure. (12) The tube according to embodiment 11, further having two discontinuous spines formed by patterning adjacent radial slots offset by 90°. (13) The tube according to embodiment 12, wherein the intermittent spines are configured to define two bend planes aligned perpendicularly along the longitudinal axis. (14) The tube according to embodiment 11, wherein the radial slots include a helical pattern and the slots are aligned to form one or more continuous spines. (15) The tube according to embodiment 11, wherein the radial slots extend around the entire circumference of the longitudinal axis of the tubular support frame structure, and the radial slots form a series of rings in the axial direction between the proximal end and the distal end.

[0108] (16) The tube according to embodiment 15, wherein the ring has a connecting mechanism configured to engage with an adjacent ring. (17) A support tube for the body of the catheter, A substantially cylindrical braided pattern formed by multiple strands centered on the longitudinal axis, defining the lumen of the support tube extending through the support tube, One or more spines extending longitudinally between the proximal and distal ends along the braided pattern, A support tube comprising a polymer cover disposed around at least a portion of the braided pattern. (18) The support tube according to embodiment 17, wherein at least one of the one or more spines is woven with the strand of the braided pattern. (19) The support tube according to embodiment 17, wherein the angle formed by the braiding of the strands of the braided pattern is in the range of about 20 to 90°. (20) The support tube according to embodiment 17, wherein the polymer cover encloses at least a portion of the braided pattern.

Claims

1. A tube that forms the main body of the catheter assembly, A tubular support frame 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 that are arranged along the length of one or more spines and extend through the support frame structure, defining the lumen of the support frame structure, The support frame structure includes a polymer cover disposed around at least a portion of the support frame structure, The support frame structure further includes a spine connector, the spine connector having a confluence point where it meets three or more of the plurality of ribs, and a joint point spaced apart from the confluence point and joining to one of the one or more spines, The three or more ribs include a central rib, a distal rib located distal to the central rib, and a proximal rib located proximal to the central rib. The distal rib has a first curved portion that curves in the proximal direction toward the confluence point, and the proximal rib has a second curved portion that curves in the distal direction toward the confluence point. A pipe wherein the central rib is located in the same position as the spine connector in the longitudinal direction, and the central rib does not have a curved portion that curves in the proximal direction or a curved portion that curves in the distal direction.

2. The pipe according to claim 1, wherein at least one of the one or more spines has a proximal spine width different from the distal spine width between the proximal and distal ends of the support frame structure.

3. The pipe according to claim 1, further having a spacing between adjacent ribs that changes between the proximal end and the distal end of the support frame structure.

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

5. The pipe according to claim 2, wherein one or more of the spines are arranged as helical spines in a spiral shape centered on the longitudinal axis of the support frame structure.

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

7. The pipe according to claim 1, wherein the ribs are arranged at an angle of less than 90° with respect to the longitudinal axis of the support frame structure.

8. The pipe according to claim 1, wherein the joint includes a notch configured to alleviate the distortion of the support frame structure at the joint.

9. The pipe according to claim 1, wherein the rib has a non-planar cross-section in which the profile of the rib includes one or more curved portions.

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