Dual-channel thrombus removal device

Abstract

To provide a device for removing a clot from a vessel.SOLUTION: A device for removing a clot from a vessel can have dual layers where an inner expandable member runs within an outer expandable member. The inner expandable member can be divided into one or more sections, with a proximal section having a clot-pinching structure configured to pinch the clot between the pinching structure and an outer catheter. A distal flow channel section of the inner member can be configured to create a flow channel through the clot to restore blood flow for a downstream vasculature. Struts of the outer expandable member can form closed cells that are not fully circumferential in a proximal portion to thereby allow a clot to pass through and engage the pinching structure, and fully circumferential in a distal portion to make it possible to scaffold the vessel for dislodging the clot. A protective element at the distal end of the device can prevent escape of clot fragments.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to devices and methods for removing acute occlusions from blood vessels during intravascular medical procedures. More specifically, the present disclosure relates to a clot retrieval device for removing clots from blood vessels.

Background Art

[0002] The present disclosure relates to devices and methods for removing acute occlusions from blood vessels. Acute occlusions can include clots, mispositioned devices, displaced devices, large emboli, and the like. Thromboembolism occurs when part or all of a thrombus detaches from the vessel wall. This blood clot (herein referred to as an embolus) is then carried in the direction of blood flow. Ischemic stroke can result when a blood clot lodges in the cerebral vasculature. Pulmonary embolism can result when a blood clot forms in the venous system, i.e., on the right side of the heart, and lodges in the pulmonary artery or its branches. Although a blood clot can develop and occlude a blood vessel locally in the form of an embolus without resolution, this mechanism is common in the formation of coronary artery occlusions. The devices and methods described herein are particularly suitable for removing blood clots from the major cerebral arteries of patients suffering from acute ischemic stroke (AIS), from the pulmonary arteries of patients suffering from pulmonary embolism (PE), from the native or transplanted coronary vessels of patients suffering from myocardial infarction (MI), and from other peripheral arteries and veins where a blood clot is causing an occlusion.

[0003] There are many challenges related to access, which can make it difficult to deliver the device to the target site. When access involves passing through the aortic arch (such as coronary artery occlusion or cerebral occlusion), the shape of the aortic arch in some patients makes it difficult to position the guiding catheter. The tortuosity problem is even more severe in arteries approaching the brain. For example, it is not uncommon at the distal end of the internal carotid artery for the device to have to pass through a vascular segment with several extreme bends that appear one after another while moving just a few centimeters. In the case of pulmonary embolism, access can be obtained through the venous system and then through the right atrium and right ventricle of the heart. Since the right ventricular outflow tract and pulmonary artery are delicate blood vessels, they can be easily damaged by a device that is not flexible or has large protruding parts. For these reasons, it is desirable for the blood clot retrieval device to keep its protruding part as small as possible and be compatible with flexible access catheters and support catheters.

[0004] The vasculature in the region where blood clots may be clogged is often fragile and delicate. For example, the blood vessels of the neurovascular tract are more fragile than blood vessels of the same size in other parts of the body and are in a soft tissue bed. As a result of excessive tensile force being applied to these blood vessels, perforation and bleeding may be caused. The blood vessels of the lungs are larger than those of the cerebrovascular system, but are inherently delicate, especially in the more distal blood vessels.

[0005] The opportunity to use stent-like blood clot retrieval devices to remove blood clots from the cerebral blood vessels of acute stroke patients is increasing. These devices often rely on a clamping mechanism to grip the blood clot by capturing it between the self-expanding stent-like body and the blood vessel wall. There are many drawbacks to this approach.

[0006] The stent-like blood clot retrieval device continues to grip the blood clot depending on its outward radial force. This compressive force tends to dehydrate the blood clot, and when the blood clot dehydrates, its coefficient of friction may increase, and as a result, it may become more difficult to move and remove the blood clot from the blood vessel. If the radial force is too low, the stent-like blood clot retrieval device will not be able to grip the blood clot. Conversely, if the radial force is too high, the stent-like blood clot retrieval device may damage the blood vessel wall and may require an excessive force to withdraw. Therefore, a stent-like blood clot retrieval device having a radial force sufficient to handle all blood clot types can damage the blood vessel and cause serious injury to the patient. On the other hand, if the stent-like blood clot retrieval device is made to have an appropriate radial force so as to maintain non-invasiveness, it may not be able to effectively handle the blood clot type in all situations where blood clot removal is performed. As a result of sandwiching the blood clot between the stent-like blood clot retrieval device and the blood vessel wall, high shear forces are generated on the sides of the blood clot when the blood clot is removed, and fragments of the blood clot may be detached. If these fragments are not retained by the device, they may be detached and cause further occlusion within the distal vasculature.

[0007] In some conventional stent-like blood clot retrieval devices, due to the way their strut elements are connected to each other, the struts are placed under tension during withdrawal. And in such devices, when placed under tension within a vascular bend, the shape of the retrieval device when expanded cannot be held very well. This tension is due to the friction between the device and the blood vessel. And when additional loads such as the resistance caused by the blood clot are applied, this tension increases. As a result, when the stent-like blood clot retrieval device is withdrawn proximally near the bend of a tortuous blood vessel, the gripping force on the blood clot decreases, and there is a possibility that the captured blood clot may slip out. At the bend, the struts on the outside of the bend are placed under higher tension than the struts on the inside. To achieve the lowest possible energy state, the outer surface of the blood clot retrieval device moves towards the inner surface of the bend, thereby reducing the tension in the struts but also decreasing the expanded diameter of the device.

[0008] Furthermore, when attempting to remove a long blood clot, conventional devices that are shorter than the blood clot are likely to be unable to restore flow through the occluded area even when deployed. As a result, the pressure gradient across the entire blood clot continues to be a significant obstacle to its removal. Simply making such a device longer makes it difficult to move through the tortuosity of the anatomical structure, may cause trauma to the vasculature, requires more force to withdraw, and there is a possibility that the device may become immobile and surgery may be required to remove it.

[0009] As a result of pursuing the efficiency of the technique, devices consisting of multiple bodies have also been used. Such a device can have an outer body that can scaffold the target blood vessel and an inner body for embedding and collecting blood clots. These devices can function well when engaging with and removing blood clots. However, if the struts have a larger and often more rigid network structure, it may become more difficult to retract the device and partially or fully rehouse it within the outer catheter again. During this process, the members of the outer body are compressed, which may prevent the inner body from gripping the captured blood clot, or even loosen the gripping force of the inner body. Such possibilities are particularly heightened in the case of longer blood clots, or in situations where the gripping force is maintained through the gripping operation between the device and the distal tip of the outer catheter. As a result of the outer body having a larger expanded shape, when the device is partially or fully folded during retraction, the struts of the outer body may hit or deflect the inner body.

[0010] The effectiveness of a given device is also important. This is because, for many reasons, the physician may need to make multiple passes to completely remove the obstruction. However, each time the blood clot retrieval device is withdrawn, access to the target site is lost. Therefore, it may be necessary to advance the guidewire and microcatheter again to access the blood clot, advance beyond the blood clot again, then remove the guidewire and advance the blood clot retrieval device through the microcatheter. Guiding the guidewire and microcatheter to the blood clot can take a significant amount of time, especially if the blood vessel is tortuous. The additional time and device manipulation add to the risk of complications to which the patient is exposed. Therefore, it becomes clear that an effective and efficient device is important. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] No device can achieve a high level of success in removing blood clots, restoring flow, and facilitating good patient outcomes without overcoming the above-described problems. The present design aims to provide a blood clot retrieval device that is improved to address the above issues.

Means for Solving the Problems

[0012] The design described herein can be for a blood clot retrieval device for removing blood clots from the blood vessels of a body. The device can have a framework of struts that forms an elongate inner body having a proximal end, a distal end, and a longitudinal axis. The elongate inner body can be divided into one or more sections that extend distally from a proximal side shaft used to operate the device. The proximal section can have a blood clot clamping structure, which can have a folded delivery configuration when constrained within an outer catheter, an expanded blood clot engagement configuration when deployed at a target site, and a blood clot clamping configuration in which the clamping structure is at least partially constrained. As the device transitions from the engaged deployment configuration, the blood clot clamping structure can be configured to clamp and hold a blood clot when in the blood clot clamping configuration.

[0013] The blood clot clamping structure can take various forms, such as a flat pattern arranged in a gentle undulating or spiral shape. In one example, the clamping structure includes an array of segments adjacent to each other. The segments may be low-strut-density sections bounded by rings of higher strut density. Or, alternatively, the shapes may vary differently at different longitudinal positions, and the radial forces exerted by at least two adjacent segments on the blood clot may be different from each other. In another example, the clamping structure may have a series of blood clot receiving cells. The cells may consist of one or more flexible struts extending between the crowns. Thereby, the cells can clamp the portion of the blood clot within the cell when the struts are compressed. With these patterns, as the microcatheter or outer catheter advances beyond the proximal end of the clamping structure and the device transitions from an expanded deployment configuration to a partially constrained blood clot clamping configuration, it becomes possible to compress and grip the blood clot between the tip of the catheter and at least a portion of the struts of the clamping structure.

[0014] The more distal portion of the elongated inner body of the device can be a porous inner channel fixedly connected to the distal end of the blood clot clamping structure. The inner channel can include a tubular body, the annular body of which is composed of a plurality of struts defining inner body closed cells around the longitudinal axis. The cells and struts can be designed to penetrate the blood clot, apply radial forces, form a lumen through the blood clot, and restore blood flow when deployed in a radially expanded configuration. The cells can also allow portions of the blood clot to escape compression by being displaced through the cell openings. Thereby, the radial forces exerted on the blood vessel wall can be reduced, minimizing trauma to the blood vessel and reducing tensile damage to the distal vascular bed.

[0015] The device can have a double expandable member, whereby the characteristics of the inner member and the outer member can be adjusted independently of each other. In one embodiment, an inner elongated body is provided in an outer cage. The outer cage may be coaxial with the inner elongated member or may be radially offset. The outer cage can be more expandable than the inner elongated body and can be configured to be juxtaposed and supported against the wall of the target blood vessel. The inner elongated body can be substantially disposed within the lumen of the outer cage. Different radial expansions between the inner body and the outer cage can define a receiving space between them in which a blood clot can be received.

[0016] Similar to the inner elongated member, the outer cage can also have one or more sections. The cage can have a proximal first scaffold segment that has a framework of struts forming one or more proximally expandable bodies arranged longitudinally. The proximally expandable bodies can be made of non-circularly closed cells that form one or more support arms spaced around the longitudinal axis such that there is a large circumferential gap between adjacent arms. For example, the first scaffold segment of the outer cage can have two support arms that are diametrically opposed and 180 degrees apart.

[0017] The outer cage can also have a distal second scaffold segment that can have a framework of struts forming one or more distally expandable bodies arranged longitudinally. Similar to the first scaffold segment, the second scaffold segment can have a network of closed cells around the longitudinal axis. The cells of the distally expandable bodies of the second scaffold segment can be formed circumferentially throughout such that they support the blood vessel at all circumferential positions. The distal section of the elongated inner body, i.e., the porous inner channel, can be disposed within the lumen of the second scaffold segment.

[0018] The closed cells of the first and second scaffold segments of the outer cage may be larger than the cells of the inner body. As a result, the outer cage can be expanded within an occlusive blood clot in a blood vessel and configured to allow the blood clot to move into the receiving space as the cage expands.

[0019] To increase the flexibility of the device, the expandable bodies of the first and second scaffold segments can be connected to each other by hinges. Thereby, when the device advances or retracts through a bend in the vasculature, it can bend independently of each other. Additionally, the cells of each expandable body of the first and second scaffold segments can have struts that form at least one distal apex that does not include a connection to an adjacent closed cell.

[0020] In another example, the blood clot retrieval device can have a two - layer configuration having an inner elongated body disposed within a porous outer body. The inner elongated body can have a proximal blood clot engaging element, and the blood clot engaging element can have a constrained delivery configuration, an expanded blood clot engaging deployment configuration, and at least a partially constrained thrombus clamping configuration. A tubular inner channel can be present distally of the blood clot engaging element, and the channel can have a constrained delivery configuration and an expanded deployment configuration. When the tubular inner channel is expanded, it can utilize radial force to restore blood flow within the occluded blood vessel.

[0021] The blood clot engaging element may have a framework of struts configured to exert an outward radial force on the blood clot when expanded to a deployed configuration. The outward force may vary in amplitude along the length of the blood clot engaging element. In one case, the radial force generally follows a sine wave pattern. The amplitude of the wave pattern may be generally equal on both sides across the peak, or may vary at the proximal or distal end to firmly grip portions of the blood clot. The amplitude of the peak may decrease along the length of the blood clot engaging element, for example, being higher at the proximal end and lower at the distal end.

[0022] The device may also have a longitudinal axis extending through the center of the proximal blood clot engaging element and the distal tubular inner channel. The struts of the blood clot engaging element may be in a flat pattern or plane such that when deployed in an expanded state, the pattern aligns with or is positioned around the axis. In one example, the struts of the element can form a planar pattern that wraps around the axis in a helical or spiral shape. In another example, the struts can form a plurality of adjacent segments with regions of high and low strut density, or longitudinally asymmetric regions, such that the radial forces exerted by two adjacent segments are different from each other to continue to grip the blood clot better. In a further case, adjacent struts of the blood clot engaging element can have portions that bend or twist in the same or different directions, thereby changing the radial force so that when the blood clot engaging element transitions to a blood clot clamping configuration, the captured blood clot is compressed and clamped.

[0023] In a two - layer device configuration, a porous outer body having a non - circumferential proximal segment and a fully circumferential distal segment connected to the proximal segment can be disposed around the inner elongated body. The outer body can be designed to expand radially more than the radial expansion of the inner elongated body when the device is deployed from a delivery catheter. When the outer body is folded inside the catheter, the outer body can have a radial dimension equal to or larger than that of the inner body.

[0024] The proximal and distal segments of the porous outer body can each have one or more expandable bodies. Each expandable body can have a plurality of struts that form closed cells. The cells are, for example, larger than the cells of the inner elongated body. Thus, while the expandable outer body can exert a radial force on the blood clot and the target blood vessel, the outer body can provide a scaffold that allows the blood clot to pass through without preventing it from being captured by the inner body. Each expandable body of the proximal and distal segments joins with each other at at least one distal apex that does not include a connection to another adjacent closed cell. Thereby, each body can be independently bent and react to local forces, increasing flexibility. Other portions of the expandable body can have a convergence region where the struts cross an intermediate connecting strut or connecting arm that joins the adjacent bodies.

[0025] The risk of embolization during blood clot retrieval using the device can be reduced by providing a distal fragment protection element added to one or both of the inner elongated member and the outer cage. The protection element can consist of a net or scaffold zone that traverses the vascular lumen towards the distal end of the device. The element can be three-dimensional in that it has a depth in addition to a surface area. In other cases, fibers or thin wires can be utilized to provide additional scaffold within the element while minimizing any impact on the contour shape or ease of delivery of the device. By combining the fragment protection element with the scaffolds of both the inner and outer members, a more effective filter is provided than using only one member.

[0026] In one embodiment, the distal portion of the inner elongated body can have a plurality of struts configured as a fragment protection element in a three-dimensional pattern around the longitudinal axis. The distal portion of the inner elongated body can also have a framework of struts in a raised or flared shape.

[0027] In an alternative example, the fragment protection element may be connected to or be part of the distal end portion of the outer cage or member. The end portion of the outer cage may also taper through a series of distal crown struts. The crown struts of the outer member may be configured in a generally conical shape, such that the outer member may neck down distally as a natural barrier around the protection element. The struts may also intersect circumferentially so as to occupy a larger cross-sectional area, or the strands may be meshed or braided to increase the coverage rate.

[0028] A method for using a clot retrieval device to extract an occlusive clot from a blood vessel may include providing an outer catheter having a tubular body and a collar at its distal end. A clot retrieval device having an elongate shaft fitted with an expandable element may also be provided, the expandable element being capable of transitioning from a folded delivery configuration to an expanded deployment configuration. The clot retrieval device may have an inner body with a proximal clot clamping element, the clot clamping element being connected to a more distal flow path element. An outer body having a first non-circumferential scaffold section joined to a second completely circumferential scaffold section may be disposed around the inner body. The second scaffold section may have a pivotal or hinge-like connection to the first scaffold section, thereby enabling the device to accommodate a sharply bent portion within the vasculature.

[0029] This method can involve delivering the blood clot retrieval device in a folded configuration to a target occlusion, such as when it is folded or constrained within a microcatheter. The microcatheter can be directed to the target site through a guide catheter or an intermediate catheter using a guide wire or other techniques known in the art. The microcatheter can be advanced across the blood clot and then retracted to expose the blood clot retrieval device, which can be expanded within the blood clot. The gaps within the non-circumferential first scaffold section can enable at least a portion of the blood clot to be exposed to the inner blood clot clamping elements. Similarly, the radial forces resulting from the expansion of the fully circumferential second scaffold section can displace portions of the blood clot through the large outer cells and engage the blood clot with the flow path elements. The expansion of the flow path elements can open a path for at least partially restoring blood flow and re-establish the blood vessel as a flow path.

[0030] To continue this method of removing the blood clot, it is advisable to firmly maintain the position of the blood clot retrieval device while the outer catheter advances along the elongated shaft. By doing so, the collar of the outer catheter engages with the expandable element and can clamp at least a portion of the blood clot in a compressed state between the collar and the clamping element. Once the user feels the resistance indicating that the blood clot is clamped and being continuously held, the blood clot retrieval device, along with the captured blood clot, can be removed from the blood vessel, with the relative positions of the outer catheter and the expandable element of the blood clot retrieval device maintained such that the collar remains engaged. The blood clot retrieval device and the clamped blood clot can then be completely removed from the patient.

[0031] In many cases, after retrieving some or all of the occlusive clot, contrast agent can be injected through the outer catheter so that a more thorough evaluation of the presence or absence of vascular occlusion can be made. If an occlusion remains within the blood vessel, the thrombus removal device can be passed through the catheter a few additional times. Then, once it is confirmed that the target blood vessel has appropriately reopened its blood flow, all remaining devices can be removed from the patient. The present device provides means for minimizing the number of times the catheter needs to be advanced, which is required to treat the patient, thereby reducing the potential for the blood vessel to be damaged and the risk that the blood vessel will be severed in relation to that damage when it is necessary to pass the catheter multiple times.

[0032] Other aspects and features of the present disclosure will become apparent to those skilled in the art by considering the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0033] The foregoing and further aspects of the present invention will be further considered with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate functionally similar or identical elements. 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 example and not by way of limitation.

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[0034] The object of the disclosed design is to create a blood clot retrieval device capable of more effectively and efficiently removing occlusions within a vascular structure while maintaining a high level of deliverability and flexibility during the procedure. The design can have an outer expandable member within which an inner expandable member runs. The disclosed plurality of devices share the common theme of a two-layer structure where the inner member has the ability to capture blood clots with minimal interference from the outer member. Both members can be directly or indirectly connected to an elongate shaft, and a distal net or scaffold configured at the distal end of the device can prevent blood clot fragments from escaping. This distal net can be attached to any one or several of the shaft, the inner member, or the outer member.

[0035] Intended for this two-layer structure is to allow blood clots to enter through the large openings or gaps of the outer expansion member and be present within the receiving space provided between the two expandable members. At least a portion of the inner member can have a higher density scaffold than the scaffold of the outer member, thereby preventing blood clots from entering its lumen and forming a flow path across the blood clot once the device is deployed across the blood clot.

[0036] Both the inner expandable member and the outer expandable member are preferably made of a material that can automatically recover its shape when released from a significantly distorted delivery configuration. The material can be in many forms, such as, for example, wire, strip, sheet, or tube. A particularly suitable manufacturing process is to laser cut a nitinol tube and then heat treat and electropolish the resulting structure to create a framework of struts and connection elements. As described, a design range is envisioned for each of these elements, and any of these elements is intended to be usable with any other element. However, to avoid repetition, these elements are not shown in all possible combinations.

[0037] Here, specific examples of the present invention will be described in detail with reference to the drawings. The description will often be made in relation to mechanical thrombectomy treatment, but the present design can also be adapted to other procedures and other body internal passages.

[0038] Regardless of whether it is a coronary vessel, a pulmonary vessel, or a cerebral vessel, accessing various vessels within the vascular system to reach a blood clot involves well-known procedural steps and the use of many conventional commercially available accessory products. The above products, such as angiographic materials, rotary hemostatic valves, delivery access catheters, and guidewires, are widely used in laboratory procedures and medical procedures. When these or similar products are used in conjunction with the disclosure of the present invention in the following description, their functions and exact configurations will not be described in detail.

[0039] Referring to FIG. 1, the blood clot retrieval device 100 can have an elongated shaft 6 and an expandable structure configured at the distal end of the elongated shaft 6, and the expandable structure has an inner member and an outer member. These members can be the outer cage 210 and the elongated inner body 110, which are for capturing blood clots and promoting the restoration of blood flow passing through the blood clots after the blood clot retrieval device 100 is deployed at the target site. The outer cage 210 can be a scaffold structure having large cells, but the blood clots can pass through those cells and enter the receiving space 9 defined by the annular region between the elongated inner body 110 and the outer cage. The fragment protection element 14 can be disposed near the tapered end 218 of the outer cage 210 near the distal end 4 of the device 100. The outer cage 210 and the elongated inner body 110 can have a configuration folded inside a microcatheter for delivery and an expanded configuration for blood clot retrieval, blood flow restoration, and fragment protection.

[0040] The inner member and the outer member are preferably made of a superelastic or pseudoelastic material such as nitinol or another alloy having a high recoverable strain. The shaft 6 can be a tapered wire shaft and can be made of stainless steel, MP35N, nitinol, or other materials suitably having a high elastic modulus and tensile strength. The shaft 6 and the device 100 can have an indicator band or marker for indicating to the user that the distal end of the device is approaching the end of the microcatheter during insertion, or for marking the distal end of the device during the procedure. These indicator bands can be formed by being printed on a region of the shaft, by removing a region of the shaft, or by masking for coating so that they are visually distinguishable from the rest of the shaft, and as a result, they are visually distinguishable from the rest of the shaft.

[0041] The shaft 6 may be coated with a material for reducing friction and thrombogenicity, or may have a polymer jacket for such purposes. The coating or jacket described above may consist of a polymer, a low-friction lubricant such as silicon, or a hydrophilic / hydrophobic coating. This coating can also be applied to the outer cage 210 and the elongated inner body 110.

[0042] The two-layer multi-diameter device 100 shown in various figures throughout the present disclosure has several advantages. The inner body 110 having a smaller radial dimension can be firmly embedded in the target clot, providing a firm grip with a sharp opening angle, while the outer cage 210 has a larger radial dimension, thereby continuing to contact and be juxtaposed with the blood vessel wall and protecting against the movement of the clot in the distal direction as the device is retracted proximally into a blood vessel having a gradually increasing diameter.

[0043] The top view of the composite device 100 having the double expandable members of FIG. 1, i.e., the inner expandable member and the outer expandable member, is shown in FIG. 2. Both the inner body 110 and the outer cage 210 may be monolithic structures, and the outer cage is configured to substantially enclose the inner body. The cells of the outer cage 210 function as an inlet for blood clots, and when the outer cage 210 retracts, it allows the outer cage 210 to apply a force in a direction substantially parallel to the direction in which the blood clot is pulled from the blood vessel (i.e., a direction substantially parallel to the longitudinal axis 8). This means that the outward radial force applied to the vascular structure can be maintained at a minimum. By configuring the outer cage 210 to facilitate the transverse movement of the blood clot to the receiving space 9, the device can more effectively dislodge the blood clot from the wall of the blood vessel. The outer cage 210 can also have an enclosed distal end 218, and the distal end 218 defines a surface configured to cooperate with the fragment protection element 14 as a blood clot fragment barrier surface.

[0044] The elongated inner body has a plurality of regions, whereby, after deployment, it can provide both a force to strongly grip the blood clot and a strong opening force to form a lumen for restoring blood flow. The elongated inner member 110 can have a proximal blood clot clamping section 120, and this section 120 can provide a force to strongly grip the blood clot for a very important initial step of dislodging the blood clot from the blood vessel, and allows the outer cage 210 to be configured to have only a small radial force.

[0045] The distal section of the elongated inner body 110 can be a porous inner channel 130, which is configured to form a blood flow lumen through at least a portion of the blood clot. This blood flow lumen can reduce the pressure gradient across the entire blood clot, making it easier to move and remove the blood clot. The porous inner channel 130 may be tubular and have a diameter that can be adjusted to reduce the risk of damage during blood flow restart upon expansion. This restricted blood flow through the lumen ensures that the pressure applied to the blood vessel immediately after blood flow recovery is reliably lower than normal, thereby reliably reducing the risk of bleeding in the vascular bed. Subsequently, complete blood flow can be restored by removing the device and the captured blood clot.

[0046] As shown in FIG. 3, the outer cage member 210 can be a plurality of struts forming an expandable body, which is configured to self-expand to a diameter larger than the radial size of the inner body 110 when released from a restraining sheath (such as a microcatheter). The proximal expandable body 216 can be disposed around the blood clot gripping or clamping section 120 of the inner body 110, while the distal expandable body 217 can be disposed around the porous inner channel 130. Proximally, the outer cage 210 can have support arms 222, which are joined to the shaft 6 at the proximal junction 212 and flare radially to form the proximal expandable body 216. The support arms 222 may have a tapered cross-section as shown, ensuring a gradual transition in stiffness from the shaft 6 to the blood clot engaging expandable portion of the device. The support arms 222 can be oriented to form a reticulated structure of closed cells at discrete positions around the longitudinal axis 8 of the device 100 such that there is a large circumferential gap between adjacent arms. For example, two sets of arms 222 can be approximately 180 degrees apart and substantially diametrically opposed to each other as shown. Alternatively, three sets of arms can be spaced 120 degrees apart.

[0047] The proximal portion of the outer cage 210 can have an expandable body 216, but the expandable body 216 has cells that do not completely surround the perimeter around the device and provides a scaffold that is lower than the height of the scaffold of the distal expandable body 217. A portion of the blood clot can pass into the gap between the cells of the proximal expandable body 216 and the support arm 222 and is adapted to be engaged by the blood clot clamping structure 120. By having cells within the proximal expandable body 216 that are not completely circumferential, a lower surface contact area and a radial force are provided that allow the blood clot to more easily protrude into the gap within this section of the device. When the device is retracted into the outer catheter, the blood clot clamping structure 120 can continue to securely grip the blood clot without interference collisions from the struts of the arm 222 of the outer cage 210. The support arm 222 can also have a bend or crown that biases movement away from the blood clot clamping element or at least in a direction not the same as that element. Thereby, when the proximal portion of the device is partially constrained by the outer catheter, the support arm is adapted not to shear a portion of the blood clot.

[0048] The proximal expandable body(s) 216 can be connected by connecting struts 233 to the most proximal body of the distal expandable body 217. In one example, these connecting struts 233 can be generally linear struts that extend parallel to the central longitudinal axis 8 of the device. In other embodiments, these connecting struts 233 can have multiple struts configured in one or more cells, or can have curved or helical arms. The region between adjacent expandable bodies 216, 217 can form an inlet 214 through which a blood clot or portion of a blood clot can enter the receiving space 9 between the elongated inner body 110 and the outer cage 210.

[0049] The most distal portion of the outer cage 210 can have a tapered end 218 that tapers radially inward with a substantially conical profile toward the distal junction 213. The taper and convergence of the struts at the tapered end 218 reduces the aperture diameter of the openings between the struts to form a debris capture zone. These struts can be end crown struts 237 connected to the most distal side of the expandable body 217 via connection struts 234, as shown in FIG. 3. The end crown 237 may be convexly raised or flared, whereby the end of the outer cage 210 is non-invasive to the blood vessel in which it is used. The struts forming the raised or flared portion may not be parallel to those of the adjacent portion of the outer cage and may form joints or hinges through which the tapered end 218 can bend or flex around the distal expandable body 217. The junction 213 can have or be provided with radiopaque properties for marking the distal end of the device 100 during the procedure, or can be a twisted or coiled assembly of fibrous struts.

[0050] The distal expandable body 217 can be connected by one or more connecting arms 234. These connecting arms 234 can extend from the proximal junction 239 to the distal junction 240, as seen in the side view of the outer cage 210 in FIG. 4. The connecting arms 234 can be generally straight and run parallel to the longitudinal axis 8 of the device 100. In other cases, these connecting arms may comprise a plurality of struts configured in one or more cells, or may have a curved arm or spiral cross-section. The region between the distal expandable bodies 217 can define an inlet 214 through which a blood clot passes into the receiving space 9. The connecting arms 234 between the distal expandable members 217 may be substantially aligned with the connecting struts 233 between the proximal expandable body 216 and the distal expandable body 217 to align the neutral axis of the body during flexion.

[0051] The proximal expandable body 216 and the distal expandable body 217 of the outer cage 210 can have a series of interconnected struts for forming closed cells. For example, certain struts such as the crown strut 232 terminate at a crown or distal top 236. However, no distal connecting element connects to any adjacent closed cell. Also, other body struts, such as strut 242, terminate at a body junction point 244. The distal top 236 may be offset from the longitudinal axis 8 of the device 100 and, upon expansion, may be close to the cylindrical surface defined by the outer cage 210. The crown struts 232 that join at the distal apex 236 may be widely curved, thereby maximizing the offset and spacing between the apices and achieving a desirable balance between providing a scaffold to the blood clot and the flexibility of the device. Having free apices 236 without distal connections at some junctions allows for higher bend flexibility of the device. This is because, in addition to the bending of the struts forming each cell, the apex itself has some ability to bend to accommodate bends within the vascular structure and to withstand the forces of the blood clot.

[0052] The outer cage 210 can expand and contact the vessel wall when the microcatheter is retracted during deployment of the device. This contact provides stability to the device 100 and minimizes torsion as any helical portions of the inner elongate body 110 and the clamping section 120 are uncovered within the blood vessel. This facilitates the uniform deployment and expansion of the device 100 within the occlusion or blood clot.

[0053] Expansion of the outer cage 210 can cause compression and / or displacement of the blood clot during expansion, depending on the height of the scaffold support provided by the struts. When the expandable body provides a higher scaffold, the blood clot can be compressed. Alternatively, when the expandable body provides an escape route or opening, the expandable body biases the blood clot towards the opening. The blood clot itself can have many degrees of freedom and can move in a variety of different directions. By providing an outer cage 210 that is equal to or longer than the length of the occlusive blood clot, many of the degrees of freedom of movement available to the blood clot are removed. Since the inlet opening 214 is provided within the outer cage 210 and guides the major degree of freedom of movement available to the blood clot, when the outer cage is expanded, the blood clot is biased into the receiving space 9. This allows the blood clot to be retrieved without excessive compression. This is advantageous because compressing the blood clot can cause the blood clot to dehydrate, and dehydration increases the frictional properties and stiffness of the blood clot, making it more difficult for the blood clot to detach from the blood vessel and be removed. When the outer cage expands outwardly towards the blood vessel wall, if the blood clot can easily move inwardly through the cells or the gaps within the proximal portion of the outer cage, the above compression can be avoided.

[0054] Another advantage of using a self-expanding body is that when the device 100 is deployed across the blood clot, due to the three-dimensional characteristics and stiffness of the targeted blood clot, initially the resistance may only allow the device 100 to expand by a portion of its freely expandable diameter. This gives the outer cage 210 the ability to further expand to a larger diameter while being retracted. As a result, the outer cage 210 can remain in contact with the vessel wall while being retracted into the larger and more proximal blood vessel.

[0055] Figure 5 shows the elongated body 110 inside the device 100 of FIG. 2. The blood clot engaging clamping section 120 and the porous inner channel 130 can be integrally formed from a single strip or tube of shape memory material, such as nitinol, and then laser cut to form a strut pattern. Alternatively, they can be formed independently and attached later, allowing both members to take on various shapes. The inner body 110 can also have a proximal joint or transition between the proximal end 121 of the clamping section 120 and the elongated shaft 6 on which the device is mounted.

[0056] The elongated inner body 110 can be configured to expand to a diameter smaller than the diameter of the smallest blood vessel in which it is intended to be used. If the inner body is non-tapered, the diameter of the inner body is typically less than 50% of the diameter of the expanded outer cage, and in some cases can be reduced to 20% or less of the diameter of the outer cage. This allows the portions of the inner body to be constructed of very little material, since these portions only need to expand a portion of the length of the diameter of the outer cage and can therefore have very high flexibility in both the folded and expanded states. This flexibility advantageously allows the inner body to be displaced in one direction by one portion of the blood clot and in another direction by another portion of the blood clot.

[0057] The blood clot clamping section 120 may be an engagement element within a more proximal region of the elongated body 110 inside the device 100. The clamping section 120 is intended to facilitate blood clot retrieval by expanding between the blood clot and the blood vessel wall in such a way that it engages the blood clot over a relatively large surface area while minimizing compression of the blood clot. The above section can be constructed such that while having a highly compressed ring with deep strut embedding, there are scattered regions with minimal blood clot compression and low radial force, so that overall blood clot compression is minimized. A portion of the blood clot can protrude into the low compression regions and can be clamped between the tip of the catheter and the struts of the device. The clamping is achieved by advancing a microcatheter or outer catheter beyond the proximal end 121 of the clamping section until a portion of the blood clot is compressed between the tip of the catheter and the crown or struts of the clamping section 120. This clamping increases the gripping force of the device on the blood clot, especially on fibrin-rich blood clots, facilitating removal of the blood clot. This can also stretch the blood clot, reducing the force required for movement by pulling the blood clot away from the blood vessel wall during the movement process. Retention of the blood clot during withdrawal of the microcatheter or outer catheter can be improved, but it is necessary to control the proximal end of the blood clot to prevent it from getting caught in the collateral vessels.

[0058] Distal to the blood clot clamping section 120, the inner channel 130 can be generally tubular, planar, or some other shape, but has a lumen structure with a diameter smaller than the peripheral portion of the outer cage 210. In one example, the distal inner channel 130 may transition from the distal end 122 of the blood clot clamping section to form a barrel shape, such that this section has a radial size smaller or larger than the proximal clamping section 120 in the illustrated expanded configuration. This enables the formation of a flow path across a very long blood clot without overly compressing the blood clot or engaging the inner channel 130 with the blood vessel wall. The inner channel 130 may be formed integrally with the clamping section or may be formed separately and connected via a collar or other mechanical joint. In other cases, the inner channel 130 may have a non-cylindrical cross-section, a non-uniform diameter, or a strut pattern adjusted to provide different radial forces or regions of flexibility.

[0059] In another example, the shape may be substantially tubular and may have a plurality of struts spaced apart, away from, and converging toward the axis 8 of the device as shown in FIG. 5, and the strut-forming cells 132 are configured to pass through the blood clot in the expanded state, engage with the lumen for blood flow, and define a lumen through which blood flows through the blood clot. When expanded, the cells 132 interpenetrate the blood clot and can provide additional gripping force to assist in the initial movement of the blood clot, while at the same time scaffolding the lumen for blood flow through the blood clot to prevent the detachment of fragments.

[0060] The distal end 136 of the inner channel 130 may transition to or be connected to a tether or shaft, or may transition to the debris protection structure 14. The debris protection structure 14 may be a three-dimensional pattern, a woven mesh filter or an entangled mesh filter, or a plurality of struts configured in a basket-like or conical shape, thereby preventing or collecting debris from moving distally of the device. The structure 14 may also be a fiber bundle in a spherical or similar shape. In the expanded state, at least a portion of the debris protection structure may have a radial size larger than the flow channel 130 and the clamping section 120 and may be of a size similar to the diameter of the target blood vessel. The distal end of the debris protection element 14 may have a radiopaque coil element 16 that may be laser cut from the same tube used to construct the inner channel 130 during the procedure.

[0061] The inner elongated body 110 and the outer cage 210 may be joined at the proximal side at the shaft 6 and at the distal side during assembly to minimize the tension between the members in use. The struts of the blood clot clamping segment 120, the inner channel 130, or both, can be lengthened or shortened such that when loaded into the microcatheter and when freely expanded at the target site, the length of the inner body and the length of the outer cage are substantially the same. The closed cells of the inner body and the outer cage can allow the device to accommodate a small length difference by elongation without applying significant tensile or compressive forces to the joints along the coil element 16. The length difference can occur, for example, when the device is expanded, folded, or deployed in a small blood vessel.

[0062] An enlarged and exaggerated view of the blood clot clamping section 120 of the elongated body 110 inside FIG. 5 is shown in FIG. 6. The alternative ring segments 145 can be formed by overlapping struts to form an intermediate crown 147 at local vertices. The section of low-density fruting 146 extends between successive annular segments 145 and can be bounded by the successive annular segments 145. In this section, longitudinally extending bridge struts provide a lower height scaffold and reduced radial forces as compared to those produced by the ring segments 145. The overlap of the struts when the clamping section 120 expands or contracts allows each ring segment 145 to be twisted relative to its adjacent ring, where each twist cancels out the next twist such that in the clamping section, the overall twist at the distal end 122 relative to the proximal end 121 is minimized. The minimal twist helps ensure that the force for gripping the clamped blood clot is not lost.

[0063] The longitudinal length of the bridge struts between the rings 145 of struts in the low-density fruting 146 can vary. For example, when used in the middle cerebral artery, the longitudinal spacing can be about 3 - 6 mm. This spacing allows the blood clot to protrude between the struts where the blood clot engages the clamping section in the expanded deployment configuration. The lengths and / or total numbers of the ring segments 145 and the fruting section 146 can be optimized for the lengths and densities expected for optimal embedding within the blood clot. The bridge struts 144 between the ring segments 145 can be straight and parallel to the axis 8 of the device so that they can be better pushed to ensure that the device can be delivered through a tortuous anatomical structure.

[0064] The struts of the clamping section 120 can also have one or more bends 148 at various axial positions along its length. The "dogleg" type of shape formed by these bends 148 in the strut 144 may be repeated around the circumference or radially around the section to form cells. The bends 148, or the lengths of the struts 144 that vary by location, or the angles formed by different struts in the pattern, may be of different widths so that the various segments can have higher expansion forces in order to improve engagement with the blood clot in the deployed configuration where the various segments are expanded. This structure can be manufactured by laser cutting a nitinol raw material and heat setting the shape, thereby allowing it to take on the desired profile upon expansion.

[0065] Another example of an inner elongated body 110 having a proximal engagement element configured as a blood clot engaging clamping section 120 and a distal inner channel 130 is shown in FIG. 7. When fully expanded, the clamping section 120 can have the same or a different radial size as the inner channel 130, but the two structures may be formed monolithically, such that there is no significant stiffness transition at the distal end 122 of the clamping section. The fragment protection element 14 may be formed at or otherwise attached to the distal end 136 of the inner channel 130 and may be configured to transition to an expanded radial size that is larger than both the blood clot clamping section 120 and the inner channel when the device 100 is deployed across the blood clot.

[0066] The clamping section 120 can have more densely packed ring segments 145 along its length portion as compared to that of FIG. 5. As already discussed, this segment 120 can have a ring 145 of struts and a region of low radial force and strut density 146. By spacing adjacent ring segments 145 close to each other at a particular axial position of the clamping section 120, the effect of clamping between the rings in the blood clot clamping configuration can be increased as the microcatheter or outer catheter advances.

[0067] During retraction, the clamping of the fibrin-rich blood clot can be lost, or the blood clot may include a red blood cell-rich "soft" segment that is not fully gripped by the proximal clamping section 120. In these scenarios, the struts of the distal porous inner channel 130 can provide engagement with the blood clot and retrieve the blood clot through the increased diameter blood vessel, over the bend, and past the branch to the microcatheter or outer catheter. Further, the expanded cells and / or struts of the fragment protection element 14 engage any free fragments or un-gripped blood clot sections with minimal shear force.

[0068] Referring to FIG. 8, another inner elongated body 110 having some features similar to the other devices described above is shown. The elongated inner body 110 can be attached proximal to the shaft 6. This connection can be a collar or some other axial restraint that allows at least partial relative rotation between the outer cage 210 and the inner body. A radiopaque marker (not shown) can be used at this location to mark the proximal end point of the expandable portion of the device 100 during the procedure.

[0069] The inner body 110 can have a proximal blood clot engaging element 120 and a more distal, tubular inner channel 130. A three-dimensional mesh-like structure or basket can be formed from wires or fibers into a fragment protection element 14, which is held at the distal end 136 of the distal inner channel 130 and retained within the outer cage 210. The wires or fibers may be crimped and / or twisted to occupy space within the structure, or formed into a specific pattern.

[0070] The blood clot engaging element 120 can have struts that form a plurality of adjacent segments 152, and if adjacent segments have different shapes, as a result, the radial forces generated by successive adjacent segments may not be equal. Some struts can have bends 148 (such as those seen in FIG. 6) so that when the blood clot engaging element transitions from an expanded deployed configuration to a partially constrained blood clot clamping configuration, adjacent struts 144 can compress the blood clot. Some struts of adjacent segments 152 can overlap obliquely at an angle with respect to the longitudinal axis 8 of the device, such that they can slide in different directions relative to each other when disposed within or moving through a bend within a vascular structure. Additionally, portions of adjacent segments 152 can have features that bias them to fold along a particular plane or that change their axial or radial length. Differences in strut length ensure that the radial force applied to the blood clot by the clamping section 120 varies while facilitating thrombus retrieval in cooperation with a microcatheter or outer catheter, achieving good gripping of the thrombus.

[0071] In another example of the apparatus 100 shown in FIG. 9, the strut pattern of the blood clot clamping section 120 of the inner elongated member 110 can be formed by laser cutting a mostly flat two-dimensional sheet and then wrapping the resulting flat pattern around a cylindrical mandrel before thermosetting. Next, the centerline of the device can form a helical or spiral pattern around the longitudinal axis 8, similar to the process of wrapping a ribbon around a cylinder. At the proximal end, the blood clot clamping structure 120 can be connected to the shaft 6. The inner channel 130 connected to the distal end 122 of the blood clot clamping section 120 may also be a flat pattern, may have a curved or contoured cross-section, or may generally be tubular in shape as shown in other disclosed examples.

[0072] When deployed across the blood clot, portions of the blood clot can move through the inlet 214 and into the receiving space 9 or the device through the cells of the expandable bodies 216, 217 of the outer cage 210 or the spaces between the expandable bodies. Here, the blood clot can project into the low strut density region and also into the central lumen of the spiral pattern of the blood clot clamping structure 120. The gaps in the proximal expandable body 216 and the lower scaffold facilitate entry of the blood clot clamping structure 120 into the helix. When the device 100 is then retracted, the above helix can improve the gripping and removal performance as the outer catheter advances distally to transition the device from the expanded deployment configuration to the partially constrained blood clot clamping configuration and can also facilitate the blood clot clamping operation. Such effects can also be increased when the blood clot clamping structure 120 of the device 100 is constructed from two or more spiral-shaped components.

[0073] The spiral shape of the helix also allows the portion of the blood clot clamping structure 120 to stretch under tension and to stretch a portion of the blood clot during removal. The proximal end of the blood clot can be clamped and restrained on the blood clot clamping structure 120, while the distal end of the blood clot is disposed on the inner channel 130 and can fill and open the flow path. If the distal end of the blood clot remains blocked in the blood vessel, the inner channel 130 and the outer cage 210 can remain stationary while the blood clot clamping section 120 expands in some sections and contracts in other sections in response to the force of the blood clot. This action can help to dislodge the blood clot from the blood vessel wall and reduce the force required to remove it during the procedure.

[0074] The fragment protection element 14 can be connected to the distal end 136 of the inner channel 130 by a tether or shaft 134. The protection element 14 can be a three-dimensional pattern that expands to a radial size greater than the radial size at any point along the cross-section of the elongated inner body 110. The shape of the element can be a conical basket as shown, or a mesh element or a bundle of fibers that occupies sufficient space to prevent distal passage of the blood clot or thrombus fragment.

[0075] The exact shape and configuration of the strut network of the clot engaging element 120 and the adjacent segment 152 determine the radial forces applied at different axial positions along the structure when the element is in the expanded deployed configuration and the clot engaging configuration. The forces can determine, for example, the amplitude 128 of the force at that position in a substantially sinusoidal waveform pattern 124 having a locally varying peak 126. A sample plot of the radial force as a function of the axial position along the clot engaging element 120 is shown in FIG. 10 to illustrate this concept. The amplitude 128 can repeat at distances patterned to be relatively equal along the length of the engaging element 120. Alternatively, if the clot is to be disengaged with an initial grip for clamping, it can repeat at distances patterned such that the force is low at the distal end 122 and higher at the proximal end 121 and can decrease along the length. This plot shows, for example, how the ring segments 145 embedded in the clot can have a greater radial force than the low density fruting segments 146 between the rings. The effectiveness of the regions of increased radial force can be increased by maximizing the angle of the struts with respect to the longitudinal axis of the blood vessel, which can enable the ring segments 145 to grip rather than slide past the clot. By having these different regions of radial force, the device 100 can maintain a grip on the clot within the regions of the peaks 126 while applying a much smaller compressive force to the clot between the peaks. This helps to minimize the overall force required to retract the clot.

[0076] As the microcatheter or outer catheter is advanced to increase the clamping force on the blood clot, the user may feel the clamping state as resistance and may stop the advancement of the catheter or advance it a fixed distance beyond the proximal end 121 of the engagement element 120 and the more proximal expandable body 216 of the outer cage 210. The lower-height scaffold within the proximal expandable body 216 of the outer cage 210 allows the relative tension between the engagement element 120 and the catheter to be maintained so that the clamping state between the engagement element and the catheter does not deteriorate during retraction of the blood clot.

[0077] The flowcharts of FIGS. 11a-11e, 12, and 13 illustrate a method of use for the disclosed design. The guidewire 11 and microcatheter 13 are inserted through the vasculature 40, guided, and advanced across the occlusive blood clot 20 using conventional known techniques. Once the microcatheter 13 is positioned distal to the occlusive blood clot 40, the guidewire 11 is removed from the vasculature 40 so that the blood clot retrieval device 100 can be advanced through the microcatheter. The device 100 is advanced in a folded configuration until the distal tip of the device reaches the distal end of the microcatheter. As shown in FIG. 11b, the microcatheter 13 is retracted while the position of the device 100 is maintained using the shaft 6, allowing the blood clot retrieval device to be deployed across the blood clot 20 in a manner where the distal end of the device is preferably positioned distal to the blood clot 20. The device 100 expands such that the outer cage 210 engages the occlusive blood clot 20 and allows the blood clot to pass radially inward. The blood clot clamping section 120 and the porous inner channel 130 can expand to embed the blood clot and provide a flow path for restoring blood flow in a controlled manner. The device 100 may be capable of incubating within the blood clot 20 for a period of time as needed as the controlled, restored blood flow through the inner channel 130 stabilizes.

[0078] FIG. 11c illustrates a blood clot 20 engaged with the device during retrieval into the microcatheter 13. As the catheter advances, the collar 12 compresses the blood clot 20 between the crown 147 of the ring segment 145 and the bridging strut 144 of the low-density fruting segment 146, as shown in FIG. 11d. Depending on the conditions, the clamping engagement may also be affected by the intermediate catheter or other outer catheters. The blood clot is partially located within the inlet opening 214 of the device and may also be partially located within the receiving space 9 defined by the region between the inner body 110 and the outer cage 210. Blood clot fragments can be trapped within the distal closed tapered end 218 of the outer cage 210 and the fragment protection element 14 to prevent the fragments from being released into the bloodstream. Blood flow occlusion, aspiration, and other standard techniques may be used during this process.

[0079] As shown in FIG. 11e, the relative tension between the device and the microcatheter can be maintained by the user during movement removal and retraction so that the clamping of the blood clot is securely maintained. When used in the present invention, clamping the blood clot using a microcatheter or an intermediate catheter has been described as providing additional advantages, but if necessary, all embodiments described herein may also be used to move and retrieve the blood clot without using catheter clamping. The distal closed end and the expanded fragment protection element 14 of the outer cage 210 of the device 100 prevent the captured blood clot fragments from being released into the bloodstream.

[0080] FIGS. 12 and 13 are diagrams each including steps of a method for performing a thrombus removal treatment using such a device. The steps of the method can be implemented by any of the exemplary devices described herein or by suitable alternatives known to those skilled in the art. The method can have some or all of the steps described, and in many cases, the steps can be performed in a different order than that disclosed below.

[0081] Referring to method 1200 outlined in FIG. 12, step 1210 may include providing an outer catheter that can have a tubular body and a collar at its distal end. Depending on the situation, the outer catheter may be a microcatheter, an intermediate catheter, or any other suitable sheath known to those skilled in the art, and has a diameter suitable for achieving clamping on the device as described above.

[0082] Step 1220 can provide a blood clot retrieval device having a folded delivery configuration, an expanded deployment configuration, and an expandable element. The device can be manipulated during the procedure using a proximal shaft. The expandable element can have an inner body and an outer body expandable in a radial range larger than the inner body. The inner body can have a proximal clamping element and a distal flow path element. The outer body can have a non-circular first scaffold section disposed around the clamping element and a fully circular second scaffold section around the flow path element, and the second scaffold section is connected to the distal side of the first scaffold section. The non-circular first scaffold segment allows a portion of the peripheral blood clot to easily pass inward through the gap in the outer body so that it engages with the proximal clamping element of the inner body.

[0083] Procedure 1230 may include delivering a collapsed delivery configuration blood clot retrieval device via a microcatheter to a blocked blood vessel. In the case of an intracranial blockage, various access routes are possible, including direct puncture of the carotid artery, a brachial approach, or a femoral access. Once access to the arterial system is obtained using conventional and well-understood techniques, a guide catheter or long sheath (not shown as part of the figures in FIGS. 11a-11e) is typically positioned in close proximity to the actual occlusive blood clot. For example, in the case of a middle cerebral artery occlusion, the guide catheter may be positioned within the internal carotid artery proximal to the carotid siphon. Next, the microcatheter can be advanced across the blood clot, with or without the aid of a guide wire. Once the microcatheter tip has traversed the blood clot and advanced to the distal side of the blood clot, the guide wire (if used) can be removed, but the blood clot retrieval device is advanced through the microcatheter until it reaches the distal end.

[0084] Next, the microcatheter can be retracted, and in Procedure 1240, the blood clot retrieval device can expand within and on either side of the blood clot. This procedure may further include expansion within the blood clot of the outer body's scaffold region and may further include applying a compressive force to bias the blood clot through the inlet cell and into the space between the inner body and the outer body. When the outer body is deployed to its expanded deployment configuration, at least a portion of the blood clot can pass radially through the circumferential gaps of the non-circumferential first scaffold section and contact at least a portion of the clamping element. Due to the large cell openings within the outer body and the gaps in the non-circumferential first scaffold section, compression on the blood clot can be controlled and minimized. By minimizing compression on the blood clot, the force applied radially outward to the blood vessel wall is reduced, thereby overcoming the frictional force when retracting the blood clot.

[0085] Continuing to refer to FIG. 13, method 1300 can have a step 1310 of preventing movement of a blood clot to a flow path element to enable blood flow through the flow path element in an expanded deployment configuration. Since the device can be configured to have a long inner body consisting of two parts, when the device is deployed, the expansion of the flow path element forms a flow path through the blood clot, restoring flow to the vascular bed distal to the blood clot and reducing the pressure gradient across the entire blood clot. This reduction in the pressure gradient reduces the force required to dislodge the blood clot from the vessel wall and retreat it in the proximal direction. Additionally, due to the flow path, the device can be safely left in a fixed position during a rest period before withdrawal. Unlike being exposed to sudden transient spikes in pressure and flow rate if the blood clot is removed immediately or if the device compresses the blood clot such that a very large flow path is created upon deployment, leaving it in place allows the distal vascular bed to be gently perfused with fresh oxygenated blood.

[0086] While maintaining the position of the blood clot retrieval device tightly, step 1320 can involve advancing the outer catheter along the elongated shaft to engage the collar of the outer catheter with the expandable element and compressing and clamping at least a portion of the blood clot with the clamping element. This can be achieved with the aid of suction through the outer and / or guide catheter, which can help maintain a firm grip on the blood clot and avoid loss of fragments. However, the disclosed design has the additional benefit of firmly gripping the blood clot, safely containing it within the receiving space, and having a distal fragment protection element and a scaffold region. The protection element may be spaced from the distal end of the inner member and is thus optimally positioned to capture any fragments released from the blood clot during retraction.

[0087] In step 1330, while maintaining the engagement between the collar of the outer catheter and the expandable element, the outer catheter and the blood clot retrieval device are withdrawn in unison from the blood vessel. Along with the suction described above, this engagement maintains a firm clamping grip on the blood clot as it is withdrawn through bends and blood vessels of continuously increasing diameter.

[0088] In procedure 1340, the clot retrieval device and the clamped clot can be removed from the patient. The device may be rinsed with saline and gently washed before being reloaded into the microcatheter as needed. Thereafter, it may be reintroduced into the vasculature for redeployment to further segments of the occlusive clot or, if further passage is required for restoration of full blood flow, it may be reintroduced.

[0089] The present invention is not necessarily limited to the described examples, which may vary in configuration and detail. The terms "distal" and "proximal" are used throughout the foregoing description and are meant to refer to the position and direction with respect to the treating physician. Thus, "distal" or "distally" refers to a position away from or a direction away from the physician. Similarly, "proximal" or "proximally" refers to a position near to or a direction toward the physician. Further, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0090] As used herein, the term "about" or "approximately" with respect to any numerical value or range of numerical values indicates a tolerance of dimensions suitable to enable a component part or collection of component parts to function in accordance with its intended purpose as described herein. More specifically, "about" or "approximately" can refer to a range of values within ±20% of the recited value, for example, "about 90%" can refer to a range of values from 71% to 99%.

[0091] 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 a similar purpose without departing from the scope and spirit of the present disclosure. It should also be understood that a reference to one or more steps of a method does not exclude the presence of additional method steps or method steps intervening between those explicitly identified. Similarly, some steps of a method can be performed in an order different from that described herein without departing from the scope of the disclosed technology. For the sake of clarity and brevity, not all possible combinations are listed, and such variations are often obvious to those skilled in the art and are intended to be within the scope of the following claims.

[0092] 〔Embodiment〕 (1) An apparatus for removing a blood clot from a blood vessel, comprising a framework of struts forming an elongated inner body having a proximal end, a distal end, and a longitudinal axis, the elongated inner body having a constrained delivery configuration, an expanded blood clot engagement deployment configuration, and at least partially constrained blood clot clamping configuration, and configured to transition from the deployment configuration to the blood clot clamping configuration to clamp the blood clot, a blood clot clamping structure, and a porous inner channel connected to the distal end of the blood clot clamping structure, the porous inner channel including a tubular body configured to form a lumen through the blood clot and configured to restore blood flow when deployed, a framework, and a framework of struts forming an expandable tubular outer cage, the outer cage being radially expandable larger than the elongated inner body, defining a receiving space between the outer cage and the elongated inner body, the outer cage having A first scaffold segment comprising one or more proximally expandable bodies including a plurality of non-circularly closed cells, wherein the blood clot clamping structure extends inside the first scaffold segment, the first scaffold segment, and A second scaffold segment comprising one or more distally expandable bodies including a plurality of completely circumferentially closed cells, which is distal to the first scaffold segment, wherein the porous inner channel extends inside the second scaffold segment, the second scaffold segment, A framework comprising An apparatus comprising (2) The struts of the porous inner channel define inner body closed cells, The closed cells of the first scaffold segment and the second scaffold segment of the outer cage are larger than the inner body closed cells, The apparatus according to Embodiment 1. (3) The apparatus according to Embodiment 1, wherein at least a part of the porous inner channel is configured to interpenetrate with the blood clot when radially expandable to the deployed configuration. (4) The non-circularly closed cells of the first scaffold segment include one or more support arms, The support arms are spaced apart around the longitudinal axis, and there is a large circumferential gap between adjacent arms, The apparatus according to Embodiment 3. (5) The apparatus according to Embodiment 1, wherein the first scaffold segment includes two support arms that are substantially diametrically opposed about the longitudinal axis.

[0093] (6) Each of the expandable bodies of the first scaffold segment and the second scaffold segment includes at least one distal apex that does not include a connection to an adjacent closed cell, the apparatus according to Embodiment 1. (7) The blood clot clamping structure includes a plurality of adjacent segments, The device according to Embodiment 1, wherein the segments are configured such that the radial forces applied from at least two adjacent segments are different from each other. (8) The blood clot clamping structure a plurality of blood clot receiving cells, a cell comprising struts extending between the crowns, the struts being configured to clamp a blood clot located within the cell as the blood clot clamping structure transitions from the expanded deployment configuration to the at least partially constrained blood clot clamping configuration. The device according to Embodiment 1, comprising (9) The blood clot clamping configuration is realized by advancing the catheter beyond the first scaffold segment and the blood clot clamping structure until at least a portion of the blood clot is compressed between the tip of the catheter and at least a portion of the struts of the blood clot clamping structure. The device according to Embodiment 1. (10) The adjacent expandable bodies of the first scaffold segment and the second scaffold segment are connected to each other by hinges. The device according to Embodiment 1.

[0094] (11) A blood clot retrieval device for removing an occlusive blood clot from a blood vessel, an inner elongated body, a proximal blood clot engaging element having a constrained delivery configuration, an expanded blood clot engaging deployment configuration, and an at least partially constrained blood clot clamping configuration, and a distal tubular inner channel connected to the distal end of the blood clot engaging element and having a constrained delivery configuration and an expanded deployment configuration, the inner channel being configured to allow blood to flow through the interior of the inner channel in the expanded deployment configuration. A distal tubular inner channel An inner elongated body comprising A porous outer body comprising a non-circular proximal segment and a fully circumferential distal segment pivotally connected to the proximal segment, wherein the outer body is radially expandable to a greater extent than the inner elongated body, the porous outer body, comprising, The blood clot engaging element further includes a framework of struts configured to apply a radially outward force to the blood clot when expanded to the deployed configuration, the outward force varying in a generally sinusoidal waveform pattern along the length of the blood clot engaging element. Device. (12) The device according to embodiment 11, wherein the amplitude of the waveform pattern is generally equal along the length of the blood clot engaging element. (13) The device according to embodiment 11, wherein the amplitude of the waveform pattern decreases along the length of the blood clot engaging element such that it is higher at the proximal end of the blood clot engaging element and lower at the distal end of the blood clot engaging element. (14) The device has a longitudinal axis (8) extending through the blood clot engaging element and the tubular inner channel, The struts of the blood clot engaging element form a planar pattern arranged in a helical configuration around the longitudinal axis, the device according to embodiment 11. (15) The blood clot engaging element further comprises a plurality of adjacent segments, The radial forces applied by at least two adjacent segments are different from each other, The device according to embodiment 11.

[0095] (16) Adjacent struts of the blood clot engaging element include at least one bend, The bend is configured to compress the blood clot against adjacent struts as the blood clot engaging element transitions to the blood clot clamping configuration. The device according to embodiment 11. (17) The proximal segment and the distal segment of the outer body each include one or more expandable bodies, The expandable body comprises a plurality of struts in the form of closed cells. The device according to embodiment 11. (18) The device according to embodiment 17, wherein each of the expandable bodies of the proximal segment and the distal segment includes at least one distal vertex that does not include a connection to an adjacent closed cell. (19) A method of treating a patient having a blood clot occluding a blood vessel, comprising: providing an outer catheter comprising a tubular body and a collar at its distal end; providing a blood clot retrieval device comprising a folded delivery configuration, an expanded deployment configuration, an elongate shaft, and an expandable element distal to the elongate shaft, the expandable element comprising: an inner body comprising a proximal clamping element and a flow path element connected distally to the clamping element; an outer body extending along a longitudinal axis and comprising a non-circular first scaffold section and a fully circular second scaffold section pivotally connected distally to the first scaffold section; ; delivering the blood clot retrieval device in the folded configuration through a microcatheter into the occluded blood vessel; deploying the blood clot retrieval device to radially pass the circumferential gap of the non-circular first scaffold section at least partially through the blood clot and bring at least a portion of the clamping element into contact therewith; while maintaining the position of the blood clot retrieval device strictly, advancing the outer catheter along the elongate shaft to engage the collar of the outer catheter with the expandable element to compress and clamp at least a portion of the blood clot with the clamping element; while maintaining the engagement between the collar and the expandable element, simultaneously removing the outer catheter and the blood clot retrieval device from the blood vessel; removing the blood clot retrieval device and the clamped blood clot from the patient; comprising. (20) The method according to embodiment 19, further comprising inhibiting movement of the clot to the flow path element and enabling blood flow through the flow path element in the expanded deployment configuration.

Claims

1. An apparatus for removing a blood clot from a blood vessel, comprising: a framework of struts forming an elongate inner body having a proximal end, a distal end, and a longitudinal axis, the elongate inner body having: a clot clamping structure having a constrained delivery configuration, an expanded blood clot engaging deployment configuration, and at least partially constrained blood clot clamping configuration, configured to transition from the deployment configuration to the blood clot clamping configuration to clamp the blood clot, and a porous inner channel connected to the distal end of the blood clot clamping structure, the porous inner channel including a tubular body configured to form a lumen through the blood clot and configured to restore blood flow when deployed, a framework; a framework of struts forming an expandable tubular outer cage, the outer cage being radially expandable to be larger than the elongate inner body, defining a receiving space between the outer cage and the elongate inner body, the outer cage including: a first scaffold segment including one or more proximally expandable bodies including a plurality of non-circumferentially closed cells, the blood clot clamping structure extending within the first scaffold segment, and a second scaffold segment including one or more distally expandable bodies including a plurality of fully circumferentially closed cells located distally of the first scaffold segment, the porous inner channel extending within the second scaffold segment, a framework; and the non-circumferentially closed cells of the first scaffold segment include one or more support arms, the support arms are spaced apart around the longitudinal axis such that a large circumferential gap exists between adjacent arms, the support arms include bends; the apparatus.

2. struts of the porous inner channel define inner body closed cells, the closed cells of the first and second scaffold segments of the outer cage are larger than the inner body closed cells, The apparatus according to claim 1.

3. The apparatus according to claim 1, wherein at least a portion of the porous inner channel is configured to interpenetrate with the blood clot when radially expandable to the deployed configuration.

4. The apparatus according to claim 1, wherein the first scaffold segment includes two support arms that are substantially diametrically opposed about the longitudinal axis.

5. The apparatus according to claim 1, wherein each of the expandable bodies of the first scaffold segment and the second scaffold segment includes at least one distal apex that does not include a connection to an adjacent closed cell.

6. The blood clot clamping structure includes a plurality of adjacent segments, The apparatus according to claim 1, wherein the segments are configured such that the radial forces applied from at least two adjacent segments are different from each other.

7. The blood clot clamping structure, a plurality of blood clot receiving cells, a cell including a crown and struts extending between the crowns, wherein the crown is a local apex where the struts intersect, and the struts are configured to clamp a blood clot located within the cell as the blood clot clamping structure transitions from the expanded deployment configuration to the at least partially constrained blood clot clamping configuration. The apparatus according to claim 1, comprising.

8. The apparatus according to claim 1, wherein the blood clot clamping configuration is achieved by advancing the catheter beyond the first scaffold segment and the blood clot clamping structure until at least a portion of the blood clot is compressed between the tip of the catheter and at least a portion of the struts of the blood clot clamping structure.

9. The apparatus according to claim 1, wherein adjacent expandable bodies of the first scaffold segment and the second scaffold segment are connected to each other by hinges.

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