Fibrin / soft clot rich mechanical thrombectomy device

Abstract

Disclosed is a design for a device capable of removing both firm and soft clots from the body's blood vessels, which can have a dual layer in which the inner expandable body of the unit extends within the outer expandable cage of the unit. The design can feature a constrained delivery configuration and an expanded deployed configuration. The outer cage can have wide open struts to allow for clot incorporation into the device. Both the inner body and the outer cage can be configured to have a shape that pinches and embeds the clot within it. The device is also capable of folding a portion of the outer cage and inverting proximally after engagement with the target clot to place the clot inside. These factors can enhance the device's ability to capture all constituent clots, allowing for safer and more effective flow restoration.

Description

Technical Field

[0001] This disclosure relates generally to apparatus and methods for removing acute blockages from blood vessels during endovascular medical treatment. More specifically, this disclosure relates to a clot retrieval device for removing clots from blood vessels. Background Technology

[0002] Acute blockages can be removed from blood vessels using mechanical devices and methods. Acute blockages can include clots, misaligned devices, migrating devices, large emboli, etc. Thromboembolism occurs when a thrombus partially or completely detaches from the vessel wall. This clot (now called an embolism) then travels along the blood flow direction, which can lead to a number of complications. If a clot remains in the cerebral vascular system, it can cause ischemic stroke. If a clot originates in the venous system or the right side of the heart and remains in the pulmonary artery or its branches, it can cause pulmonary embolism. Clots may also not be released as emboli, but rather form locally and block blood vessels; this mechanism is more common in the formation of coronary artery blockages. The devices and methods described in this article are particularly suitable for removing clots from cerebral arteries in patients with acute ischemic stroke (AIS), from pulmonary arteries in patients with pulmonary embolism (PE), from coronary arteries or graft vessels in patients with myocardial infarction (MI), and from other peripheral arteries and veins where clots have caused occlusion.

[0003] Numerous access challenges exist that can make device delivery to the target site difficult. In cases involving navigation of the aortic arch (such as in coronary artery or cerebral occlusion), the arch configuration in some patients makes positioning the guiding catheter challenging. The tortuousness challenge is even more pronounced in arteries near the brain. For example, at the distal end of the internal carotid artery, it is not uncommon for the device to have to navigate rapidly and continuously through segments of the vessel with several extreme bends over a journey of only a few centimeters. In cases of pulmonary embolism, access can be obtained via the venous system and then through the right atrium and ventricle of the heart. The right ventricular outflow tract and pulmonary artery are fragile vessels that are easily damaged by inflexible or high-specification devices. For these reasons, it is desirable for clot retrieval devices to be as compatible as possible with thin and flexible access catheters.

[0004] Stent-like clot retrieval devices are increasingly used to remove clots from cerebral blood vessels in patients with acute stroke. These devices typically rely on pinning mechanisms to capture the clot by trapping it between a self-expanding stent-like body and the vessel wall. This approach has several drawbacks.

[0005] Stent-type clot retrieval devices rely on their outward radial force to maintain their grip on the clot during retraction. This compressive force tends to dehydrate the clot, which in turn increases its coefficient of friction, making it more difficult to detach and remove from the vessel. If the radial force is too low, the stent-type clot retrieval device may lose its grip on the clot, while if the radial force is too high, the stent-type clot retrieval device may damage the vessel wall and require excessive force for retraction. Therefore, stent-type clot retrieval devices with sufficient radial force to handle all clot types may result in vascular trauma and serious patient injury, while stent-type clot retrieval devices with appropriate radial force to remain non-invasive may not be effective in handling all clot types in various thrombectomy situations. Pinning the clot between the stent-type clot retrieval device and the vessel wall also results in high shear forces against the sides of the clot when it is removed, potentially releasing clot fragments. If these fragments are not held by the device, they may migrate, leading to further obstruction in the distal vascular system.

[0006] Because the way its strut elements are connected to each other causes the struts to be under tension during retraction, some conventional thrombectomy devices are not well designed to maintain their expanded shape when placed under tension in a vascular bend. This tension is caused by friction between the device and the vessel, and it increases if additional loads are applied, such as resistance provided by the clot. This can lead to loss of clot gripping as the stent-like clot retrieval device retracts proximally near the bend in a tortuous vessel, where the captured clot may escape. At the bend, the strut located on the outside of the bend is under higher tension than the strut on the inside. To achieve the lowest possible energy state, the outer surface of the clot retrieval device moves toward the inner surface of the bend, which reduces the tension in the struts but also reduces the expansion diameter of the device.

[0007] When seeking surgical efficiency in this context, clot retrieval devices with multiple bodies are generally preferred. Such devices may have an outer body capable of supporting the target vessel and an inner body for embedding and capturing the clot. These devices engage well with and separate the clot, but a larger and generally stiffer network of struts can potentially make it more difficult to retract the device and partially or completely collapse the clot for re-insertion into the external catheter. Furthermore, because these devices are designed such that the clot typically needs to migrate radially inward through the external structure, the device may have a less secure clamping effect on the peripheral region of the clot.

[0008] Furthermore, conventional thrombectomy devices are typically designed to remove fibrin-rich or soft clots. Currently, prior to the introduction of thrombectomy devices, it was impossible to identify whether a clot was fibrin-rich or soft and fragile (or some combination of both), thus preventing users from knowing which device would improve first-pass success and reduce patient risk. In addition, clot heterogeneity can mean that the clot may include a fibrin-rich core in the proximal, central, or distal portions of the entire clot anatomy, making uniform and secure clamping more difficult.

[0009] Any device needs to overcome the aforementioned challenges to deliver a high level of success in removing any type of clot, restoring blood flow, and promoting good patient outcomes. The present invention is designed to provide an improved clot retrieval device that addresses these deficiencies. Summary of the Invention

[0010] The design disclosed in this invention addresses these problems by providing a flexible, double-layered clot retrieval device, wherein internal and external components work together to capture and remove clots. This design can be intended for use as a first-pass device, characterized by its effectiveness in capturing fibrin-rich, viscous clots as it is in capturing soft, fragile clots.

[0011] The design can be characterized by both constrained delivery and expansion deployment configurations. The external member may have wide-opening struts to allow the clot to be incorporated into the device. Both the internal and external members can be constructed and shaped to clamp and embed the clot. In some examples, at least portions of the device are capable of folding and inverting proximally after engagement with the target clot, thus inverting the clot inward and protecting it. These actions increase the safety of the device's clamping of the clot during all stages of retrieval, allowing for safer and more efficient flow recovery.

[0012] The device may have a proximal tubular shaft for manipulation, the proximal tubular shaft having a lumen extending through it. The shaft may have various sizes depending on the application. In one example, the shaft is a thiocyanate tube with an outer diameter less than or equal to 0.021 inches. In another example, the shaft may have an outer diameter of approximately 0.026 inches. The distal side of the shaft may be a strut frame having a restricted delivery configuration, an expansion clot engagement deployment configuration when deployed at the target site, and at least a partially restricted clot clamping configuration.

[0013] In some examples, the strut frame can form an elongated inner body and an outer retainer. In one case, the inner body and outer retainer can be laser-cut from a single continuous thallium tube. In another case, the proximal axis, inner body, and outer retainer can all be cut from the same continuous thallium tube. The inner body may have a distal end, a longitudinal axis, and one or more clot clamping units configured to clamp clots when the device transitions from a deployment configuration to a clot clamping configuration. The outer retainer may be arranged around the inner body, extending from the distal end of the inner body, or a combination of these. The outer retainer can expand to a radial extent greater than that of the expanded inner body, or it may have the same or similar radial dimensions.

[0014] The clot clamping structure can take various forms. The clamping structure may have a series of clot receiving holes. The unit may consist of one or more flexible struts extending between the coronal portions. The unit may have horseshoe-shaped saddle points at both the proximal and distal ends, allowing the unit to contract portions of the clot within the unit when the struts are under radial compression. These patterns allow microcatheters or external catheters to be advanced over the proximal ends of the clamping structure unit to compress and hold the clot located between the catheter tip and at least a portion of the unit's struts as the device transitions from an inflatable deployment configuration to a partially constrained clot clamping configuration. In another example, the clot clamping structure may be a flat pattern of struts arranged in an undulating or helical manner.

[0015] The characteristics of the inner body and the outer cage can be customized independently of each other. The outer cage can be coaxial with the inner body or radially offset. The inner body can be substantially arranged within the cavity of the outer cage.

[0016] In some examples, the pull wire extends through the lumen of the proximal tubular shaft and is securely connected to the outer retainer at a connection point. The connection point can be at least one of a crimp clamp, a welded joint, or a braid. The user manipulates the pull wire at the proximal end of the shaft to change the outer retainer from an expanded deployment configuration to an inverted clot shell configuration. During this change, the pull wire inverts the outer retainer such that at least a portion of it folds at the change point and folds proximally back over the inner body. Thus, the struts of the outer retainer can enclose the clot and the inner body in a clot shell configuration. This inversion places and accommodates both the soft and firm portions of the clot internally for subsequent retraction and removal. In some cases, the remaining distal portion of the outer retainer may also flare radially outward when the pull wire is activated to serve as a debris protection element during clot retrieval.

[0017] In some examples, the radial dimensions of the inner body and outer retainer may be thermally shaped and varied depending on the application and the potential location of the target occluder within the vascular system. For targets in neurovascular systems, the elongated inner body may have an outer diameter of approximately 2.25 mm in the expanded deployment configuration. Similarly, the outer retainer may have an outer diameter of approximately 5 mm in both the expanded deployment and inverted clot shell configurations.

[0018] Another design for the clot retrieval device may have a longitudinal axis, a proximal axis, an inner body, an outer retainer, and a tapered support mesh connected to the distal end of the outer retainer. The inner body, outer retainer, and support mesh may have a restricted delivery configuration, an expansion deployment configuration, and a clot clamping configuration that is at least partially restricted. After deployment on the clot, the clot clamping configuration is achieved by advancing a conduit over the proximal ends of the inner body and the outer retainer until at least a portion of the clot is compressed between the end of the conduit and at least a portion of the support mesh of the inner body, the outer retainer, or a combination of the inner body and the outer retainer.

[0019] In some examples, the inner body may have struts forming a series of clot-receiving units. In an expanded deployment configuration, the units may be heat-shaped to extend along the longitudinal axis in a generally sinusoidal pattern. In another example, the units form a helical pattern around the axis. In one case, the units of the inner body are configured to embed and stabilize the clot during expansion. In another case, the units of the inner body may have at least one bend configured to embed and stabilize at least a portion of the clot. The inner body may have a radial dimension range. In some examples, the inner body in an expanded deployment configuration may have an outer diameter ranging from 1.25 mm to 1.5 mm.

[0020] The external retainer may have a series of segments extending axially along the length of the device. Each segment may have one or more units. In some examples, each segment may have two units. Each unit of the external retainer may have a horseshoe-shaped saddle point located at the proximal and distal ends of the unit, the horseshoe-shaped saddle point being configured to compress and clamp at least a portion of the clot as the device moves into the clot clamping configuration. The clot clamping configuration is achieved by advancing the catheter over the proximal ends of the inner body and the outer retainer until at least a portion of the clot is compressed between the end of the catheter and at least a portion of the support bar of the external retainer as the support bar is radially compressed. Adjacent axial segments may be articulated by a flexible connecting support bar, which may be the only point of contact between the respective segments. Thus, these segments may flex independently as the device is advanced or retracted through bends in the vascular system.

[0021] Depending on the target location within the vascular system, the external retainer can be of various sizes. In one example, the external retainer in an expanded deployment configuration may have an outer diameter of approximately 3 mm. In another example, the external retainer in an expanded deployment configuration may have an outer diameter of approximately 5 mm.

[0022] The inner and outer bodies can share the same shaft and are coaxial about a longitudinal axis. At the proximal joint with the shaft, the outer retainer can have a fully circumferential tubular outer bushing that surrounds the shaft. The inner body can be formed by laser-cutting a tube with an outer diameter smaller than the inner diameter of the outer bushing of the outer retainer. Therefore, the inner body can have a bushing at the proximal joint, which can slide within the outer bushing.

[0023] A method for extracting both firm and soft clots from a blood vessel using the examples disclosed in this invention as a first-pass device may include an apparatus having an inner body, an outer retainer, and a proximal axis. The inner body may be integrally formed by laser-cutting a tube and has struts forming units configured to embed at least a portion of the clot. In some cases, the outer retainer may also be cut from the same continuous tube and extend distally toward the inner body. In other cases, the outer retainer may extend about the inner body along a longitudinal axis and be capable of expanding to a greater radial extent than the inner body. The outer retainer may also have struts forming units configured to embed at least a portion of the clot, but also allowing partial radial inward migration of the clot. The apparatus may have a restricted delivery configuration, an expanded deployment configuration, and a at least partially restricted clot clamping configuration.

[0024] The method may include the step of delivering the device to a blood vessel adjacent to the site of the target clot. The clot composition may be compact, soft, or a mixture of both compact and soft components. The device may be expanded from a restricted delivery configuration to an expanded deployment configuration such that the device is not fitted to embed at least one unit of the outer retainer and at least one unit of the inner body into the clot.

[0025] Another step may involve advancing the external conduit distally such that it engages and impacts the proximal ends of the internal body and external retainer to clamp at least a compacted portion of the compressed clot using the unit of the internal body and external retainer. The external conduit may be a microcatheter, inlet conduit, or other suitable external sheath. Clamping is maintained during device retraction to prevent loss of grip on the clot.

[0026] In some examples, the units of the inner body and / or the outer retainer may have struts forming curved or horseshoe-shaped saddle points, which are shaped to be compressed by advancing the outer conduit distally. The method may then further include the step of clamping at least a portion of the clot in the horseshoe-shaped saddle point of at least one unit of the inner body unit when engaged with the outer conduit. Alternatively or additionally, the method may further include the step of clamping at least a portion of the clot in the horseshoe-shaped saddle point of at least one unit of the outer retainer unit when engaged with the outer conduit.

[0027] If the clot is fragile and lacks rigidity for clamping, the user may experience a lack of tactile resistance when the device's shaft retracts or the external conduit is advanced distally. In this case, the external conduit can be withdrawn, and the device can be redeployed to an expanded configuration to accommodate the clot. In some examples, the external retainer's struts can be inverted back above the device, and the method may involve inverting the struts proximally to house the clot and inner body. When the external retainer struts are inverted, the inner body remains in place, preventing the clot from being pushed proximally.

[0028] When the device captures a firm clot and / or a soft clot, the method may involve the steps of removing the clot from the patient's body and retrieving the device and the captured clot. This can be accomplished, for example, by using aspiration to retrieve the device proximally back into the guiding catheter. If the firm portion of the clot can be clamped, the clamp can be maintained during this step to avoid losing hold on the clot. Alternatively, this configuration can be maintained if the external retainer's struts are inverted proximally (using tensioned traction wires or other methods) to invert the clot inward and help secure it.

[0029] After some or all of the occlusive clot is retrieved, the patency of the vessel can be assessed. If emboli remain in the vessel, additional clearance can be achieved using the clot retrieval device. Once adequate recanalization of the target vessel is observed, any remaining device can then be removed from the patient. However, the device disclosed herein provides a means of minimizing the number of catheter advances required to treat the patient, thereby reducing the likelihood of vessel injury and associated vascular anatomical risks when multiple passes are necessary.

[0030] Other aspects and features of this disclosure will become apparent to those skilled in the art after viewing the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0031] The foregoing and other aspects of the invention will be further discussed with reference to the following description and the accompanying drawings, in which similar reference numerals indicate elements that function similarly or identically. The drawings are not necessarily drawn to scale; rather, the emphasis is on illustrating the principles of the invention. The drawings depict one or more specific embodiments of the device of the invention by way of example only and not by way of limitation.

[0032] Figure 1 This is a view of a clot retrieval device according to various aspects of the present invention;

[0033] Figure 2 The invention illustrates aspects thereof. Figure 1 The clot retrieval device uses a pull line to invert the outer retainer's struts toward the proximal side;

[0034] Figures 3A to 3C A method of use of a clot retrieval device for capturing clots having both soft and compact components, according to various aspects of the present invention, is shown;

[0035] Figures 4A to 4B A method of using a clot retrieval device for capturing soft clots according to various aspects of the present invention is shown;

[0036] Figures 5A to 5B The invention illustrates aspects thereof. Figures 4A to 4B The continuation of the methods and steps in;

[0037] Figure 6 This is a plan view of another example of a clot retrieval device according to various aspects of the present invention;

[0038] Figure 7 According to various aspects of the present invention Figure 6 A front view of the clot retrieval device;

[0039] Figure 8 The invention illustrates aspects thereof. Figure 6 A perspective view of the internal main body of the clot retrieval device;

[0040] Figure 9A The invention illustrates aspects thereof. Figure 6 A floor plan of the internal structure;

[0041] Figure 9B The invention illustrates aspects thereof. Figure 6 A front view of the interior main body;

[0042] Figure 10 It is according to various aspects of the present invention for use Figure 6 A view of an exemplary proximal connector of a clot retrieval device;

[0043] Figure 11 This is a flowchart outlining the method of using the clot retrieval device according to various aspects of the present invention. Detailed Implementation

[0044] The purpose of the design disclosed in this invention is to create a clot retrieval device that can more effectively and efficiently remove clots of various compositions from the vascular system, while maintaining a high level of deliverability and flexibility during surgery. This design can be a first-pass clot retrieval device that can be used to remove any type of clot, whether they are firm and sticky, soft and fragile, or a combination of both.

[0045] The design may have an external expandable retainer within which an internal expandable body extends. Both the internal body and the external retainer may have large openings, allowing radial forces to allow partial migration of the clot into these openings. One or both units of the internal body and the external retainer may have features configured to clamp at least a portion of the clot as the external conduit is advanced distally on the device. These clamping designs increase the clamping safety of the clot retrieval device. The device may also be configured such that at least a portion of the device can be inverted proximally to invert the clot internally and protect it during retrieval.

[0046] Both the internal and external expandable components are advantageously made of a material that can automatically recover its shape once released from a high-strain delivery configuration. A suitable manufacturing process could be laser-cutting of the nitinol tubes, followed by heat setting and electropolishing of the resulting structure to form the strut frame and connecting elements. As described herein, a range of designs are envisioned for each of these elements, and any of these elements can be combined with any other element; however, to avoid repetition, they are not shown in any possible combinations.

[0047] Access to various blood vessels within the vasculature to reach a clot (whether coronary, pulmonary, or cerebral) involves well-known surgical procedures and the use of many routinely available commercially available accessory products. These products are well-known and widely used in laboratory and medical procedures. Their function and exact construction are not described in detail when used in conjunction with the disclosure of the invention described below.

[0048] Specific examples of the invention will now be described in detail with reference to the accompanying drawings. Although this specification is in the context of mechanical thrombectomy in many cases, the design is also applicable to other surgical procedures and other body access methods.

[0049] See Figure 1The clot retrieval device 100 may have an elongated shaft 6 from which a support frame 102 extends distally, wherein the inner body 110 and the outer retainer 210 are capable of expanding from a collapsed or restricted delivery configuration to an expanded deployment configuration at the target site of the vascular occlusion or clot. Delivery can be made via, for example, a microcatheter 13 or other external catheters or sheaths, depending on the access requirements of the target location. When the distal end of the microcatheter 13 is exposed, the device 100 can self-expand to… Figure 1 The deployment configuration is shown. The occlusion is typically a thrombus (blood clot) that obstructs blood flow in a blood vessel. The configuration with both an inner body 110 and an outer retainer 210 allows the clot to remain within the device, which minimizes the risk of vascular injury during removal.

[0050] The internal body 110 may be a network of struts forming an axial series of units 116. The struts of unit 116 may have high radial forces upon expansion to facilitate interpenetration and embedding of the units within the clot. The proximal and distal ends of each unit may taper into a generally “U”-shaped or horseshoe-shaped saddle point 118. This shape of the saddle point 118 allows the unit 116 to radially contract as the microcatheter 13 or another external catheter is advanced over the proximal end of the device. This contraction clamps the compacted portion of the clot embedded within one or more units.

[0051] Having multiple clamping units 116 can facilitate the capture of clots with fibrin cores in proximal, central, and / or distal locations within the clot. As the device retracts into the external conduit, the units can firmly clamp the clot until resistance is felt, indicating that the clamping elements can be further secured by aspiration.

[0052] Clamping, especially in cases of predominantly fibrin-rich clots, facilitates clot removal by enhancing the grip of the clot. Clamping also reduces detachment force by elongating the clot during disengagement from the vessel wall. Clot retention can be improved by controlling the proximal end of the clot and preventing it from obstructing lateral branches during retraction into the microcatheter or external catheter.

[0053] The ends of adjacent units 116 can be connected by a flexible connecting strut 117. The connecting strut 117 can act as a hinge between units and can be the only point of contact between adjacent units. Therefore, as the device is advanced or retracted through the bends in the vascular system, individual units can flex independently and can respond locally to the forces exerted on the device by the captured clots.

[0054] The outer retainer 210 can be securely connected to the distal end 114 of the inner body 110. The slightly curved ring of the outer retainer 210 provides a non-invasive profile to the device 100 near the distal end 4. In some examples, the inner body 110 and the outer retainer 210 can be integrally formed, whereby the struts of the inner body become struts of the outer body and take on the shape of the outer body. This is in Figure 1 As shown, the transition point 115 at the distal end 114 of the inner body 110 transitions to the larger annular structure of the outer body 210. Cutting and heat-setting the inner body 110 and the outer retainer 210 from the same tube simplifies the manufacturing process and eliminates potential kinks in the stiffness gradient of the device.

[0055] The struts of the outer retainer 210 can be very flexible with low radial force to allow manipulation of the struts via traction wire 218 or other suitable actuation methods, thereby changing the shape of the outer retainer as needed. The flexibility of the struts also allows the outer retainer 210 to collapse to the outer diameter 122 of the inner body 110 for navigation through narrower blood vessels.

[0056] The inner body 110 and the outer retainer 210 may preferably be made of a hyperelastic or pseudoelastic material such as nitinol or other such alloys having high recoverable strain and appropriately high modulus and tensile strength. An advantage of using a self-expanding body made of these materials is that, due to the volumetric properties and stiffness of the target clot, resistance during deployment across the clot can cause the device 100 to initially expand only to a portion of its free expansion diameter. This gives the outer retainer 210 the ability to expand further to a larger diameter while retracting, allowing it to juxtapose with the vessel wall as the outer retainer retracts into the progressively larger and more proximal vessel.

[0057] In one example, the inner body 110 and the outer retainer 210 can be laser-cut from a single continuous tube that also serves as the shaft 6. If desired, the shaft 6, which also functions as a tube, allows the lumen 7 of the shaft tube to be used as a conduit for a pull wire 218 or other actuating components or devices.

[0058] The tubing can be in the form of raw materials, such as nitinol-Nhohyop tubing, allowing the struts of the inner body 110 and outer retainer 210 to be laser-cut and heat-shaped to the desired shape and size. For example, when expanded to a deployment configuration, the inner body 110 can be heat-shaped to have an outer diameter 122 of approximately 2.25 mm. Similarly, in the same deployment configuration, the outer retainer 210 can be heat-shaped to have an outer diameter 222 of approximately 5.00 mm. The device can thus be effectively spring-loaded within the microcatheter and expanded to these dimensions when deployed at the target site.

[0059] The radial dimensions of the external retainer 210 allow it to remain in contact with and juxtaposed against the vessel wall, and prevent clot migration distally as the device retracts proximally into the gradually increasing diameter of the vessel. Juxtaposition with the vessel wall also reduces the axial force required for initial clot separation from the vessel.

[0060] Figure 2 It shows Figure 1 An exemplary configuration of the device 100 after capturing a clot (not shown). The unit 116 of the inner body 110 serves as an inlet to stabilize the clot and allows the device to apply force to the clot in a direction substantially parallel to the direction of pulling the clot out of the blood vessel (i.e., substantially parallel to the longitudinal axis 8) upon retraction. This also means that any outward radial force applied to the vascular system by the external retainer 210 can be kept to a minimum.

[0061] When the unit 116 of the inner body 110 is embedded within the clot, the pull wire 218 can be tensioned and retracted to invert the flexible struts of the outer retainer 210 proximally, as shown, to invert the inner body and clot internally. The pull wire 218 can be retrieved using a handle positioned proximally at the end of the device shaft. The wire 218 can pull the larger diameter outer retainer 210 while the inner body 110 remains in place, such that clamping is maintained between the saddle point 118 of the inner body unit 116, the microcatheter 13, and at least the compacted portion of the clot, as described.

[0062] When inverted, the outer retainer 210 may be characterized by a series of wide segments 216 arranged around the longitudinal axis 8 and the inner body 110. At the distal end 114 of the inner body, the inner body / outer retainer transition point 115 may form a distal coronal portion 220 to act as a segmental protection element during clot removal, thereby preventing distal migration of fragments. The coronal portion 220 may also have an expanded diameter similar to that of the target vessel, thus helping to securely capture fragments from the fragile portion of the clot.

[0063] Shaft 6 can be selected to be compatible with commonly available delivery sheaths of material tubing size. In one example, the outer diameter 9 of shaft 6 can be less than about 0.021 inches to ensure compatibility with microcatheters with an inner diameter of 0.021 inches. In another example, shaft 6 can have a slightly larger outer diameter of about 0.026 inches to be compatible with microcatheters with an inner diameter of 0.027 inches.

[0064] The shaft 6 and other parts of the device 100 may also have indicator strips or markings (not shown) to indicate to the user during insertion when the distal end of the device approaches the end of the microcatheter, or to mark the end of the device during surgery. These indicator strips may be formed by printing, removing, or masking areas of the shaft used for coating, or by using radiopaque elements visible under fluoroscopy, so that they are visually distinguishable from the rest of the shaft.

[0065] Shaft 6 may also be coated with a material or have a polymer sheath to reduce friction and thrombosis. The coating or sheath may consist of a polymer, a low-friction lubricant such as silicone, or a hydrophilic / hydrophobic coating. The coating may also be applied to some or all of the outer cage 210 and the inner body 110.

[0066] Figures 3A to 3C A method is shown for using device 100 in a vascular system 40 to capture non-uniform aggregates 20, 22 having both compact and soft components. Figure 3A In this configuration, the device can be deployed within the clot from the microcatheter 13, with unit 116 of the inner body 110 segment exposed to the clot. The microcatheter 13 can then be advanced distally to re-insert unit 116 of the inner body 110 and at least a portion of the traction wire 218. Alternatively, another external catheter or sheath can be used. The saddle point 118 can form a natural inflection point for the radially downward fold of unit 116. If a fibrin-rich portion 20 of the clot is present, unit 116 can achieve clamping of the clot segment between the inner body 110 and the microcatheter, as... Figure 3B As shown.

[0067] Once clamping is achieved and the user feels the resistance, the pull line 218 can be retracted via shaft 6. At connection point 219, the pull line pulls the larger diameter heat-set portion of the outer retainer 210 proximally, while simultaneously keeping the inner body 110 in place to maintain clamping. Retraction of the pull line 218 withdraws segment 216 of the outer retainer 210 back onto both the firm portion 20 and the soft portion 22 of the clot, thus placing the entire clot within the outer retainer, as... Figure 3C As shown. The complete device, along with the clot, can then be withdrawn back into the guide tube or other external sheath.

[0068] The connection between the pull wire 218 and the struts of the outer retainer 210 at the connection point 219 can be achieved by a variety of methods. In some examples, mechanical connections such as crimping, braiding, or ball / ring combinations can be used. In other cases, thermal processes such as welding or brazing can be used.

[0069] Figures 4A to 4B as well as Figures 5A to 5B The method of using the device is shown if only a soft clot 22 is present. The device can be deployed within the clot 22 such that the unit 116 of the inner body 110 is exposed and embedded within the clot, as... Figure 4A As shown. In Figure 4B In the middle, the microcatheter 13 can be advanced distally to re-insert into at least a portion of the unit 116 of the inner body 110 and the traction wire 218 in an attempt to clamp the clot, such as Figure 4BAs shown. If the user does not feel any clamping resistance between the internal body 110 and the microcatheter, it indicates that the clot 22 is soft (without one or more fibrin-rich portions). The device can then be redeployed from the microcatheter 13 to re-enter the internal body 110 and stabilize the clot. Figure 5A The user can then tension the pull line 218 and pull it proximally to invert the outer retainer 210 while keeping the inner body 110 in place to invert the soft gel 22 inside. Figure 5B The coronal portion 220 prevents distal migration of clot fragments while allowing the intact device and clot to be withdrawn back into the guiding catheter.

[0070] exist Figure 6 The plan view shows another example of a clot retrieval device 300 that can serve as a first-pass device for capturing both firm and soft clots. Device 300 may have a restricted delivery configuration for delivery via a microcatheter, an expanded deployment configuration, and a at least partially restricted clot clamping configuration for holding firm or fibrin-rich clots. Device 300 may have an expandable structure with a longitudinal axis 8, a proximal axis 6, and struts forming an inner body 310 and an outer retainer 410. Similar to other designs, the inner body 310 and outer retainer 410 may be cut from a shape memory alloy such as nitinol to allow the struts to be heat-shaped into the desired shape upon expansion. The inner body 310 and outer retainer 410 help retain the clot within the device, reducing the risk of damage to the vessel wall during retrieval as the clot is not brushed against the vessel wall for clamping.

[0071] The inner body 310 can be configured to stabilize the clot during removal and to provide enhanced support and additional clamping for particularly soft clots. The inner body 310 can be a thin, series-type clot-jointing unit designed to have an “S-wave” or sinusoidal final heat-set shape. The thin design allows for more clot receiving space between the inner body 310 and the outer retainer 410 to minimize clot shear when retrieving the device back into the intermediate or other external catheter. In one example, the inner body 310 may have an expanded outer diameter in the range of approximately 1.25 mm to 1.5 mm. In other examples, when the inner body and outer retainer are crimped together and inserted into the microcatheter for delivery to the target site, the inner body may have an expanded diameter determined by differences in fluoroscopic shortening.

[0072] Figure 7 It shows Figure 6A side front view of the device 300. The outer retainer 410 may have a series of axial body segments 412 arranged around the inner body 310 and heat-shaped to have an outer diameter 422 that is significantly larger than the inner diameter 322 of the inner body. In some preferred examples, this outer diameter 422 may be about 5 mm. Each segment 412 may have one or more units 416, with horseshoe-shaped saddle points 418 at the proximal and distal ends of each unit.

[0073] For example, Figures 6 to 7 The illustrated device 300 has two units 416 perpendicular to each other in each segment 412 around the longitudinal axis 8. It should be noted that, due to the... Figure 6 and Figure 7 The plan and front views shown illustrate the vertical properties of unit 416. Each unit in the main body segment 412 can have a 180-degree curvature, where flexible connecting struts 417 serve as the top / bottom of adjacent units when the device 300 rotates 90 degrees. Therefore, the result can be a cylindrical shape of the outer retainer 410 around the longitudinal axis 8.

[0074] The expansion of the external retainer 410 can cause compression and / or displacement of the clot during expansion, depending on the level of support provided by the struts. When the expandable body provides a high level of support, the clot can be compressed. Alternatively, when the expandable body provides an escape path or opening, the expandable body pushes the clot toward the opening. The clot itself can have many degrees of freedom and can move in many different directions. When the device is long enough, many of the clot's available degrees of freedom are eliminated. This allows the clot to be retrieved without excessive compression. This is advantageous because compression of the clot can lead to its dehydration, which in turn increases the clot's frictional properties and stiffness, making it more difficult to detach and remove from the vessel. Such compression can be avoided if the clot can easily migrate inward through the unit of the external retainer.

[0075] Therefore, from Figure 6 and Figure 7 The unit 416 of the illustrated device 300 may have a wide-opening support bar so that once the unit is deployed in the clot, the clot migrates radially through the outer retainer 410. Similar to other examples, distal advancement of a microcatheter or other catheter after deployment can compress the saddle point 418 of each unit 416 to clamp the fibrin-rich portion of the clot, thereby providing a firm hold during removal.

[0076] Adjacent segments 412 of the external retainer 410 can be joined by flexible connecting struts 417. With the saddle point 418 tapering the ends of the units 416 of each segment 412 to points, a single connecting strut 417 can be the sole point of contact between the respective segments. This allows the segments to hinge around the connecting struts to improve device flexibility and juxtaposition to the vessel wall. The connecting struts also allow the units 416 of each segment to locally open to an increased diameter to maintain good clamping of the clot between the inner body 310 and the external retainer 410. This ability to locally enlarge to a larger diameter can be particularly useful when some or all of the target clot is located in difficult anatomical structures such as bifurcations, thus allowing the clot to remain within the vessel.

[0077] The external retainer 410 may also have a final segment with a tapered mesh end 420 to prevent small fragments from breaking off from the main clot and re-occluding in smaller, more distal vessels. The mesh end 420 also helps prevent segments of the clot from dislodging during retrieval as they flip or change shape. The distal struts forming this segment 420 may bulge or expand, making the distal end of the external retainer 410 non-invasive to the vessel using it. The tapering and convergence of these struts also reduces the mesh aperture size to create an effective fragment capture zone.

[0078] Figure 8 It shows Figure 6 and Figure 7 A perspective view of the internal body 310 of the device 300. The sinusoidal waveform design of the body unit 316 can be seen because the struts contain bends 319 between the amplitude peaks 317 of the pattern. The bends 319 of the unit 316 can bias movement away from or at least not in the same direction as the clot clamping unit 416 of the outer retainer 410, so that the internal body 310 stabilizes but does not shear the clot portion when the proximal portion of the device is partially confined in the clot clamping configuration. The bends or coronal portion also help provide better clot gripping, specifically by embedding and balancing the clot in response to the critical initial step of disengaging the clot from the blood vessel, allowing the outer retainer 410 to be constructed with low radial forces.

[0079] The unit 316 and corrugated shape of the inner body 310 allow the device to accommodate small length differences through stretching, without imposing significant tensile or compressive forces on the connector. Length differences can occur, for example, when the device expands, collapses, or is deployed in a small blood vessel. The corrugated arrangement of the struts of the inner body unit 316 also allows the unit to extend and shorten sufficiently such that the lengths of the inner body 310 and the outer retainer 410 can be substantially the same when loaded in a microcatheter and when freely expanding at the target site. However, the unit can still have sufficient structural rigidity so that the device 300 can be advanced or retracted without excessively lengthening or shortening the inner body 310 and the outer retainer 410.

[0080] The inner body 310 can also transition distally from a single-unit sinusoidal pattern to an assembly of radially expanded struts 318. In the example shown, four expanded struts 318 can be positioned equidistantly at 90-degree intervals around the longitudinal axis. The expanded or inflated struts can facilitate the distal mesh fragment segments 420 of the outer retainer 410. During the pressing of the device into an insertion tool or microcatheter, the expanded struts can also align the perspective shortening of the inner body 310 and the outer retainer 410.

[0081] Figure 9A and Figure 9B Each provides an external retainer 410 independent of the device 300. Figure 8 Top and side views of the interior main body 310. Figure 9A A sequence of unit openings 316 in the inner body 310 is shown. Each wave may have a single unit opening 316. The unit may have a diameter of approximately 1.25 mm to 1.5 mm, or may have a slightly different diameter determined by the difference in fluoroscopic shortening between the inner body 310 and the outer retainer 410 during the pressing of the device into the insertion tool or microcatheter. Expanded struts 318 near the distal end 314 may have a larger outer diameter than the units 316 of the inner body 310 (closer to the expanded outer diameter of the outer retainer), and thus these struts may also constitute a significant portion of the required contraction length between the inner body and the outer retainer.

[0082] Figure 9B It shows Figure 9A The side view clearly shows the sinusoidal pattern 315 of the unit 316 of the inner body 310. The nearest unit of the pattern may terminate at a connecting strut 330, which connects the nearest unit to a partial circumferential inner liner 328 at the proximal end 312 of the inner body. The strut of the inner body may be integrally formed with the liner 328 by cutting and machining a single thallium tube to have an outer diameter 324 equal to the outer diameter of the liner. The distal end 314 of the inner body 310 may have a radiopaque coil 310 or a marking strip to mark the end of the device during surgery.

[0083] The proximal connection between the inner body 310 and the outer retainer 410 and the elongated shaft 6 can be configured such that the inner body and the outer retainer can have some small independent translations relative to each other. The translations can be, for example, linear translations along the axis, rotations of one body relative to the other body, or some combination of these actions. Figure 10The exploded view shows an example of a joint that can achieve this using the bushing assembly 426. The proximal end 413 of the outer retainer 410 may have a tubular bushing 427 externally connected to the elongated shaft 6. The proximal end 312 of the inner body 310 may have a partially circumferential inner bushing 328 that rides on the elongated shaft 6 as described above. The partially circumferential inner bushing 328 may be cut from a thallium tube with an outer diameter 324 smaller than the inner diameter 428 of the tubular bushing 427 of the outer retainer 410. This configuration allows the inner bushing 328 to be located radially inside the tubular outer bushing 427, such that either the inner body 310 or the outer retainer 410 can rotate slightly relative to the other. The partially circumferential arrangement also allows the inner bushing 328 to be assembled together with the fully circumferential outer bushing 427 on the shaft 6.

[0084] The coaxial bushing assembly 426 of the inner bushing 328 of the inner body 310 and the outer bushing 427 of the outer retainer 410 allows the two bodies to be substantially aligned with the neutral axis of the device 300 during bending within the vascular system. The rotational capability between the outer retainer 410 and the inner body 310 allowed by the bushing assembly 426 also helps prevent clot shear, which could otherwise occur through a static and fixed connection.

[0085] Figure 11 This diagram illustrates the steps of a method for performing a thrombectomy using such a device. The steps can be implemented using any of the exemplary devices or by suitable alternatives described herein and known to those skilled in the art. The method may have some or all of the steps described, and in many cases, the steps may be performed in a different order than that disclosed below.

[0086] See Figure 11 The method 11000 outlined herein, step 11010, may involve a clot delivery and retrieval device across a target clot of unknown composition. The clot may be compact and fibrin-rich, soft and fragile, or some combination of both. The clot retrieval device may be delivered via a microcatheter or other suitable delivery catheter and has a collapsed configuration during delivery and an expanded deployment configuration when the delivery catheter retracts. The user may use an elongated shaft manipulation device.

[0087] The expandable element of the support bar can be attached to the distal end of the elongated shaft, and the outer retainer unit and the inner body unit are located within the lumen of the outer retainer. Step 11020 may involve embedding at least one unit of the outer retainer unit and at least one unit of the inner body unit into the clump by expanding the device from a constrained delivery configuration to an expanded deployment configuration. The radial force from the expansion of the outer retainer may cause at least a portion of the clump to migrate radially inward.

[0088] In step 11030, a microcatheter or other external catheter may be advanced distally to engage at least some of the units of the inner body and outer retainer, thereby clamping at least the compacted portion of the compressed clot. The units of the inner body and / or outer retainer may be shaped to have a bend at an axial apex, which is shaped to fold radially downward as the device is partially re-inserted. The saddle point thus provides a firm clamping hold to any fibrin-rich core in the clot composition.

[0089] Distal advancement of the external catheter may continue until the user feels resistance, indicating that clamping has been achieved, or no resistance is felt, indicating that the clot does not contain fibrin-rich portions. If clamping is not achieved, step 11040 may involve withdrawing the external catheter to redeploy the device and embed it into the clot. This redeployment stabilizes the soft clot within the unit of the device.

[0090] In step 11050, some or all of the struts of the outer retainer may be inverted proximally to fold back over the clot and the inner body, and to invert the clot and the inner body inward. Inversion protects the clot and reduces potential interaction or abrasion due to friction, bifurcation, and / or sharp bending in the vascular system. The user may pull the struts proximally using a pull line that retracts and passes through the inner lumen of the device shaft, or by other suitable means. For example, the pull line may extend through the thiocyanate tube device shaft and be actuated from a shank located at the proximal end of the shaft. Furthermore, the proximal joints of the inner body, outer retainer, and slender shaft may be configured to allow some relative movement between them, thereby reducing the risk of retraction forces and clot shear.

[0091] Step 11060 may involve removing the clot retrieval device and the captured clot from the patient. This can be achieved, for example, by retrieving the device back into the external catheter using aspiration. If clamping is achieved, the clamp can be maintained by keeping the device and the external catheter in relative position during withdrawal. If necessary, the device can be rinsed and gently cleaned in saline and then reloaded into the microcatheter to reintroduce it into the vascular system at another segment where an occlusive clot is present or when further passage is required for recanalization.

[0092] The invention is not necessarily limited to the described examples, the configurations and details of which may vary. The terms “distal” and “proximal” are used throughout the foregoing description and refer to position and orientation relative to the treating physician. Similarly, “distal” or “towards distal” refers to a position away from the physician or in a direction away from the physician. Likewise, “proximal” or “towards proximal” refers to a position close to the physician or in a direction toward the physician. Furthermore, unless the context clearly indicates otherwise, the singular forms “an,” “a,” and “the / described” include plural references.

[0093] As used herein, the term “about” or “approximately” for any numerical value or range indicates a suitable dimensional tolerance that allows a collection of parts or components to achieve the intended purpose as described herein. More specifically, “about” or “approximately” may refer to a range of ±20% of the enumerated values, for example, “about 90%” may refer to a range of values ​​from 71% to 99%.

[0094] In describing the example embodiments, terminology is used for clarity. Without departing from the scope and spirit of the invention, each term is intended to be contemplated for its broadest meaning as understood by one skilled in the art, and includes all technical equivalents that operate in a similar manner to achieve a similar purpose. It should also be understood that reference to one or more steps of the method does not preclude the presence of additional method steps or intermediate method steps between those explicitly identified steps. Similarly, some steps of the method may be performed in a different order than that described herein without departing from the scope of the disclosed technology. For clarity and brevity, not all possible combinations are listed, and such variations are generally obvious to one skilled in the art and are intended to fall within the scope of the following claims.

Claims

1. An apparatus for removing clots from a blood vessel, comprising: A proximal tubular shaft, the proximal tubular shaft including a lumen extending through it; A support frame having a restricted delivery configuration, an expanded clot engagement deployment configuration, and at least a partially restricted clot clamping configuration, the support frame comprising: An elongated internal body includes a distal end, a longitudinal axis, and a plurality of clot clamping units configured to clamp the clot upon movement from the deployment configuration to the clot clamping configuration, wherein the ends of adjacent clot clamping units are connected by flexible connecting struts, and wherein the connecting struts act as hinges between adjacent clot clamping units and are the only contact point between adjacent clot clamping units; An external retainer, the external retainer being connected to the distal end of the elongated inner body and capable of expanding to a range greater than the radial extent of the elongated inner body; and One or more pull wires extend through the lumen of the proximal tubular shaft and are fixedly connected to the outer retainer, the pull wires being configured to move the outer retainer from an expanded deployment configuration to an inverted clot shell configuration.

2. The apparatus of claim 1, wherein the inner body and the outer retainer are integrally formed by laser cutting a single continuous tube.

3. The apparatus of claim 1, wherein each clamping unit includes a horseshoe-shaped saddle point located at the proximal end and the distal end of the unit.

4. The apparatus of claim 1, wherein the pull wire is connected at the connection point to the external retainer by at least one of a crimping clamp, a welded component, or a braid.

5. The apparatus of claim 1, wherein the struts of the outer retainer are configured to be inverted toward the proximal side as the outer retainer moves from the expanded deployment configuration to the inverted clump shell configuration.

6. The apparatus of claim 5, wherein the struts of the outer retainer enclose the clot and the elongated inner body in the configuration of the inverted clot shell.

7. The device of claim 1, wherein the proximal tubular shaft has an outer diameter of less than or equal to 0.021 inches.

8. The device according to claim 1, wherein the elongated internal body has an outer diameter of approximately 2.25 mm in the expanded deployment configuration.

9. The apparatus of claim 1, wherein the external retainer has an outer diameter of approximately 5 mm in the inverted solidified block housing configuration.

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