Clot removal device

Abstract

The invention relates to a clot removal device. A clot removal device for removing a clot from a body blood vessel is presented. The device may facilitate clot retrieval by expanding in a manner that engages a clot over a significant surface area. The clot may have at least one robust portion and at least one soft portion. Upon extraction, at least one robust portion of the clot may be clamped by a proximal portion of the device, while at least one soft portion of the clot may be retained by a distal portion of the device. However, separation and removal of the clot may subject a softer portion of the clot to shear or rupture, creating small floating clot fragments in the blood vessel that are no longer attached to the primary clot. The device may also capture and retain a sheared or expanded distal portion of a clot when removing the clot from a blood vessel.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to devices and methods for removing occlusions from blood vessels during intravascular medical treatment. BACKGROUND

[0002] The present invention relates to devices for removing acute occlusions from blood vessels. Acute occlusions can include clots, malpositioned devices, migrated devices, large emboli, etc. Thrombotic embolism occurs when a portion or the entire thrombus detaches from the vessel wall. This clot, now called an embolus, is subsequently transported along the direction of blood flow. If the clot originates from the venous system or the right side of the heart and lodges in the pulmonary artery or its branches, it can cause ischemic stroke. Clots can also be released not in the form of an embolus, but rather form locally and occlude the vessel, a mechanism that is more common in the formation of coronary artery occlusions.

[0003] The clot can generally be subjected to shearing or breakage upon removal from the container. The present invention is particularly suited for removing the clot in its entirety without shearing the clot and / or leaving behind a residual portion of the clot. The device can be used in cerebral arteries in patients with acute ischemic stroke (AIS), coronary native or graft vessels in patients with myocardial infarction (MI), and pulmonary arteries in patients with pulmonary embolism (PE), as well as other peripheral arterial and venous vessels occluded by clots. SUMMARY

[0004] Presented herein is a clot removal device for removing a clot from a blood vessel of a body. The device can facilitate clot retrieval by expanding in a manner that engages the clot over a significant surface area. The clot can have at least one firm portion and at least one soft portion. Upon extraction, the at least one firm portion of the clot can be pinched by a proximal portion of the device, while the at least one soft portion of the clot can be held by a distal portion of the device. The pinching can be achieved by advancing a microcatheter or an intermediate catheter over the device until a portion of the clot is compressed between the tip of the catheter and a crown or strut on the device. However, the separation and removal of the clot can subject the softer portion of the clot to shearing or breakage, creating small floating clot fragments in the blood vessel that are no longer attached to the main clot. The device is also intended to capture or hold the sheared or expanded distal portion of the clot upon removal of the clot from the blood vessel.

[0005] In some examples presented herein, a microcatheter and a guidewire can be inserted into a patient's vasculature via a retrieval catheter and advanced across a clot. When the microcatheter is in place, the guidewire can be removed to allow a clot retrieval device to be advanced through the microcatheter to the clot. The device can be advanced in a collapsed configuration. The microcatheter can then be retracted while maintaining the position of the device to deploy the device across the clot.

[0006] In some examples, the device can include a clot engagement frame, a hypotube, and a distal embolic protection system. The engagement frame can have a collapsed delivery configuration, a clot engagement deployed configuration, and a clot pinching configuration. The engagement frame can also have a proximal end, a distal end, and a distal tip. The hypotube can include a distal end that is at least partially surrounded by the clot engagement frame in a helical configuration. The distal embolic protection system can expand from a collapsed delivery configuration within the hypotube to a deployed configuration distal of the distal end of the hypotube.

[0007] In some examples, after the device is deployed across a clot, the microcatheter can be advanced distally into the engagement frame to move the engagement frame into the clot pinching configuration. In the clot pinching configuration, the struts of the proximal end of the engagement frame can be compressed to pinch a clot. The distal embolic protection system can then be advanced through the hypotube in a collapsed delivery configuration and deployed into an expanded configuration distal of the distal end of the hypotube. The struts of the engagement frame in the deployed configuration can have clot gripping surfaces to engage a clot and hold onto firm portions of the clot. Once the device is in the pinching configuration and the distal embolic protection system has been deployed, the microcatheter and the device can be retracted toward a retrieval catheter. During retraction, it can be possible that small, softer portions of the clot can break or shear off from the larger, more firm clot mass. The distal embolic protection system can act as a full capture mechanism to retain the softer portions of the clot as the device is removed. The device can be removed through the retrieval catheter.

[0008] In some examples described herein, the device can include a pull wire and a stentriever. The pull wire can be attached proximal of a distal end of the stentriever. The stentriever can include a proximal helical segment, a distal cylindrical body segment, and a distal cone. At least a portion of the helical segment can encircle the pull wire. As previously described, upon retraction of the microcatheter, the stentriever can expand from a collapsed delivery configuration to a pinching configuration and then further expand into an expanded configuration. In the pinching configuration, the distal cylindrical body segment can have a first diameter and the microcatheter can be advanced distally toward the proximal helical segment to collapse the opening of the proximal helical segment to pinch firm portions of a clot between the distal end of the microcatheter and the proximal helical segment. Once the stentriever is in the pinching configuration, the pull wire can be retracted to expand the stentriever into the expanded configuration. In the expanded configuration, the distal cylindrical body segment can expand radially to a second, larger diameter and engage any soft portions of the clot that can otherwise be susceptible to shearing or breakage upon removal of the device. After the stentriever is in the expanded configuration, the microcatheter and the device can be retracted through the vasculature into a retrieval catheter for removal from the patient.

[0009] An exemplary method for treating a patient having an occluded blood vessel can include one or more of the following steps presented in no particular order, and the method can include additional steps not included here. A clot engaging frame positioned within a microcatheter can be delivered to a target occluded blood vessel. A hypotube having a distal embolic protection system can be delivered to the occluded blood vessel with the clot engaging frame. The clot engaging frame can be deployed to contact at least a portion of a clot. The hypotube can be advanced across the clot. The microcatheter can be advanced over a proximal portion of the clot engaging frame, thereby pinching the clot. The distal embolic protection system can be deployed. The clot engaging frame, the distal embolic protection system, and clot can then be withdrawn from the patient. The method can further include pinching the clot with an outer surface of the hypotube. The method can further include capturing clot debris with the distal embolic protection system.

[0010] Another exemplary method for treating a patient having an occluded blood vessel can include one or more of the following steps presented in no particular order, and the method can include additional steps not included here. A device including a stentriever and a pull wire can be delivered through a microcatheter to the occluded blood vessel. The stentriever can be deployed to contact at least a portion of the clot such that a proximal helical portion of the stentriever forms a helix and a distal cylindrical portion of the stentriever forms a cylindrical body. At least a portion of the clot can be pinched with the helical portion of the stentriever. The pull wire can be retracted to cause the cylindrical portion of the stentriever to expand radially. The microcatheter and the device can be withdrawn together from the blood vessel. The device, the microcatheter, and the clot can then be removed from the patient. The method can further include collecting at least a portion of the clot within a distal cone of the stentriever. The method can further include positioning the device such that at least a portion of the helical segment encircles the pull wire. BRIEF DESCRIPTION OF DRAWINGS

[0011] The application will be more fully understood from the following description of some embodiments of the application, given by way of example only, with reference to the accompanying drawings in which: Figures 1A-1B Delivery of a clot retrieval device to a target location within a blood vessel is shown in accordance with aspects of the application; Figures 2A-2C Various mechanical components of a clot retrieval device are shown in accordance with aspects of the application; Figures 3A-3E Removal of a clot from a blood vessel using a clot retrieval device in accordance with aspects of the application is shown; Figures 4A-4B Delivery of a clot retrieval device to a target location within a blood vessel is shown in accordance with aspects of the application; Figure 5A and Figure 5BVarious mechanical components of a clot retrieval device according to aspects of the application are shown; Figures 6A-6C Removal of a clot from a blood vessel using a clot retrieval device according to aspects of the application is shown; Figure 7 A flowchart depicting a method of treating a patient having an occluded blood vessel according to aspects of the application; and Figure 8 A flowchart depicting a method of treating a patient having an occluded blood vessel according to aspects of the application. DETAILED DESCRIPTION

[0012] Reference will now be made in detail to the present specific embodiments of the application, one or more examples of which are illustrated in the drawings. The same or similar elements are referred to using the same or similar reference numbers. The terms "distal" and "proximal" are used in the following description with respect to the position or orientation relative to the treating physician. "Distal" or "distally" is the position or in the direction away from the physician. "Proximal" or "proximally" or "proximate" is the position or in the direction toward the physician.

[0013] Access to cerebral, coronary, and pulmonary vessels involves the use of a variety of commercially available products and routine procedural steps. Access products such as guide wires, guide catheters, angiographic catheters, and microcatheters are described elsewhere and are commonly used in catheterization laboratory procedures. These products and methods are assumed to be used in conjunction with the devices and methods of the present application in the following description and do not need to be described in detail.

[0014] The following detailed description is merely illustrative in nature and is not intended to limit the application or the application and uses of the application. While the description of the application is in many cases in the context of treating intracranial arteries, the application can also be used in other body passageways as previously described.

[0015] The expandable member of the disclosed design is desirably made of a material that is capable of automatically recovering its shape once released from a highly strained delivery configuration. A superelastic material such as Nitinol or an alloy of similar properties is particularly suitable. The material can be in a variety of forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is laser cutting of a Nitinol tube followed by heat setting and electropolishing of the resulting structure to form the framework of struts and connecting elements. The framework can be in any of the large range of shapes as disclosed herein and can be visible under fluoroscopy by the addition of alloying elements such as platinum or by a variety of other coatings or markers.

[0016] As used herein, the terms "tubular" and "tube" are to be construed broadly and are not limited to structures that are right cylinders or have a complete circular cross-section or have a uniform cross-section along their entire length. For example, tubular structures or systems are often shown as structures that are substantially right cylinders. However, tubular systems can have tapered or curved outer surfaces without departing from the scope of the present application.

[0017] The device is intended to facilitate clot retrieval by expanding in a manner that engages the clot over a significant surface area. A portion of the clot can be pinched between the tip of the microcatheter and the Nitinol strut of the device. The clot can have at least one firm portion and at least one soft portion. Upon extraction, the at least one firm portion of the clot can be pinched by the proximal portion of the device, while the at least one soft portion of the clot can be held by the distal portion of the device. This pinching can be achieved by advancing a microcatheter or intermediate catheter over the device until a portion of the clot is compressed between the tip of the catheter and the crown or strut on the device. This pinching facilitates removal of the clot because it increases the grip of the device on the clot, particularly a fibrin-rich clot. The pinching can also elongate the clot by pulling it away from the vessel wall during detachment, thereby reducing the detachment force. However, detachment and removal of the clot can cause the soft portion of the clot to shear or break, creating small floating clot fragments in the vessel that are no longer attached to the main clot. The device is also intended to capture and hold the soft, sheared or expanded distal portion of the clot as it is removed from the vessel.

[0018] Figure 1A and Figure 1B Delivery of a clot retrieval device 110 for removing a clot 101 from a vessel 100 to a target location is shown. As Figure 1A shown, a microcatheter 103 and guidewire can be inserted into the vasculature 100 via a retrieval catheter 104 and advanced across the clot 101 using conventionally known techniques. When the microcatheter 103 is positioned distal to the clot 101, the guidewire can be removed from the vasculature to allow the clot retrieval device 110 to be advanced through the microcatheter 102. The device 110 can be advanced in a collapsed configuration until the distal tip of the device 110 reaches the distal end of the microcatheter 103.

[0019] In Figure 1B the microcatheter 103 can be retracted while maintaining the position of the device 110 to deploy the clot retrieval device across the clot 101 in a manner such that the distal end of the device 110 is positioned distal to the clot 101.

[0020] As Figures 2A-2CFurther shown, the device 110 can include a clot engagement frame 112, a hypotube 111, and a distal embolic protection system 115. The engagement frame 112 can have a collapsed delivery configuration, a clot engagement deployed configuration, and a clot pinching configuration. The engagement frame can also have a proximal end 112a, a distal end 112b, and a distal tip 162. In the clot pinching configuration, at least a portion of the clot engagement frame 112 can be configured to engage a firm portion of the clot 101 in the deployed configuration and to pinch the clot 101 when moved from the deployed configuration to the clot pinching configuration. The hypotube 111 can include a proximal end and a distal end at least partially surrounded by the clot engagement frame 112 proximal to the hypotube 111 distal end. The hypotube 111 can also have a clot pinching outer surface. The distal embolic protection system 115 can move from a collapsed delivery configuration within the hypotube 111 to an expanded deployed configuration distal to the hypotube distal end. The distal embolic protection system 115 can also have a proximal edge 115a.

[0021] In Figure 2A , the device 110 is shown in a deployed configuration. As Figure 2A can be seen, at least a portion of the clot engagement portion 112 is wrapped around the hypotube 111 in a helical configuration. As Figure 2B shown, as the microcatheter 103 is advanced distally into the engagement frame 112, the engagement frame can move to a clot pinching configuration that compresses the struts of the proximal end 112a of the engagement frame in order to pinch the clot for extraction from the blood vessel. This pinching effect can be seen by the arrows shown in Figure 2A and Figure 2B . When the device 110 is fully deployed, the cells in this section are open. When the device 110 is compressed by the microcatheter 103, the cells tightly “pinch” the clot 101 between them to more firmly pinch the clot 101 for removal. As Figure 2C further shown, the distal embolic protection system 115 can be advanced through the hypotube 111 in a collapsed delivery configuration and deployed to an expanded configuration outside of the hypotube 111. The embolic protection system 115 can be deployed distal to the distal end of the hypotube 111. The embolic protection system 115 can be deployed distal to the distal tip 162 of the engagement frame 112.

[0022] In Figures 3A-3E , the use of the clot retrieval device 110 to remove the clot 101 from the blood vessel is shown. The device 110 can be advanced across the clot 101 as previously shown in Figure 1A and Figure 1B . As Figure 3AAs shown, the engagement frame 112 can expand into a deployment configuration as the microcatheter 103 is retracted. The struts of the engagement frame 112 in the deployment configuration can have clot gripping surfaces to engage the clot 101a and hold onto the solid portion of the clot 101a, thereby facilitating removal of the clot 101. After the engagement frame is in the deployment configuration, the distal embolic protection system 115 can be deployed into a deployment configuration distal of the distal tip 162 of the engagement frame 112. Then, as Figure 3B shown, the microcatheter 103 can be advanced to clamp the solid portion of the clot between the microcatheter and the engagement frame 112, as previously described. Figure 3E A close-up view of the configuration of the device 110 is provided, with the engagement frame 112 in a clamping configuration to clamp the solid proximal end of the clot 101a and the protection system 115 deployed. After the clamping is achieved, the microcatheter and device can be retracted through the vasculature toward the retrieval catheter 104, as Figure 3C shown. During the retraction, it is possible that small, softer portions of the clot 101b can break or shear off from the larger, more solid clot mass 101. The distal embolic protection system 115 can act as a full capture mechanism to hold these softer portions of the clot as the device is removed. The protection system 115 can form a barrier between the soft clot fragments 101b and the distal portion of the blood vessel to prevent the clot fragments 101b from re-entering the blood vessel and to ensure that they are removed with the rest of the clot 101.

[0023] In Figure 3D , the device 110 is removed through the retrieval catheter 104. The distal embolic protection system 115 in the expanded deployment configuration can be sized to travel through the retrieval catheter 104.

[0024] Figure 4A and Figure 4B delivery of a clot retrieval device 200 for removing a clot 101 from a blood vessel 100 to a target location is shown, which is similar to Figure 1A and Figure 1B . As Figure 4A shown, a microcatheter 103 and a guidewire can be inserted into the vasculature 100 via a retrieval catheter 104 and advanced across the clot 101 using conventionally known techniques. The clot 101 can have at least one solid portion and at least one soft portion, as previously described. When the microcatheter 103 is positioned distal of the clot 101, the guidewire can be removed from the vasculature to allow the clot retrieval device 200 to be advanced through the microcatheter 103. The device 200 is advanced in a collapsed configuration until a distal tip of the device 200 reaches a distal end of the microcatheter 103.

[0025] In Figure 4BIn this configuration, a retractable microcatheter 103 is used while maintaining the position of device 200 to deploy a clot retrieval device across clot 101, such that the distal end of device 200 is positioned distal to clot 101. Device 200 may include a pull wire 204 and a stent retrieval device 202. Pull wire 204 may be attached to stent retrieval device 202 near the distal end of stent retrieval device 202. Stent retrieval device 202 may include a proximal helical segment 206, a distal cylindrical body segment 208, and a distal cone 210. At least a portion of the helical segment 206 may surround pull wire 204. Stent retrieval device 202 may be configured to expand from a collapsed delivery configuration to a clamping configuration, and then further to an extended configuration. In the collapsed delivery configuration, stent retrieval device 202 and pull wire 204 may be located inside catheter 103. The device may also include a remote protection system 115 similar to the remote protection system described in the foregoing figures.

[0026] like Figure 5A As shown, in the clamping configuration, a portion of the pull wire 204 and the stent retrieval device 202 may be located outside the catheter 103. In the clamping configuration, the distal cylindrical body section 208 may have a first diameter D1. Figure 5B In this configuration, the microcatheter 103 can be advanced distally toward the proximal helical segment 206 to clamp the solid portion of the clot between the distal end 103a of the microcatheter and the proximal helical segment 206. As the catheter 103 moves distally, the opening of the proximal helical portion 206 of the stent retrieval device 202 collapses, thereby clamping the clot so that the proximal end of the clot is held by the catheter 103 and the proximal helical segment 206. Figure 5B As further shown, once the stent retrieval device 202 has exited the microcatheter 103 and entered the clamping configuration, the traction wire 104 can retract relative to the stent retrieval device 202 to expand the stent retrieval device 202 into an extended configuration. In the extended configuration, as the traction wire 204 moves relative to the stent retrieval device 202, the distal cylindrical body section 208 can extend to a second diameter D2. In the extended configuration, the cylindrical body section 208 can engage any soft portions of the clot that might otherwise be susceptible to shearing or breakage during removal of the device 200. As the traction wire 204 retracts proximally relative to the stent retrieval device 202, the diameter D2 of the cylindrical body section 208 can radially extend to a size greater than the diameter D1 of the cylindrical body section 208 in the clamping configuration.

[0027] exist Figures 6A-6C The image shows the removal of clot 101 from a blood vessel using a clot retrieval device 200. Figure 6A In the middle, the device 200 can be advanced across the solidified block 101, as before. Figure 4A and Figure 4B As described. Figure 6AAs shown, the stentriever 202 can expand to a deployed configuration upon retraction of the microcatheter 103. The struts of the stentriever 202 in the deployed configuration can have clot gripping surfaces to engage and hold onto the clot 101, facilitating removal of the clot 101. After the stentriever 202 is in the deployed configuration, the microcatheter 103 can be advanced to clamp the solid portion of the clot 101a between the microcatheter and the proximal helical segment 206, as previously described. After clamping is achieved, the microcatheter and the device 200 can be retracted toward the retrieval catheter 104, as shown. Figure 6B As shown, the stentriever 202 can expand to an expanded configuration. The microcatheter 103 can then be advanced to clamp the solid portion of the clot 101a between the microcatheter and the proximal helical segment 206, as previously described. After clamping is achieved, the microcatheter and the device 200 can be retracted toward the retrieval catheter 104, as shown. Figure 6C As shown, the cylindrical body segment 208 can engage any soft portions of the clot 101 that can otherwise be susceptible to shearing or breakage upon removal of the device 200, ensuring that the entire clot 101 is removed.

[0028] Other examples can include a distal embolic protection system, as previously shown. The distal embolic protection system 115 can be used as a full capture mechanism to retain these clots upon removal of the device. The protection system 115 can form a barrier between the clot fragments 101b and the distal portion of the vessel to prevent the clot fragments 101b from reentering the vessel and ensure that they are removed with the rest of the clot 101. Note, however, that this example can capture stray emboli 101b with or without the distal embolic protection system 115.

[0029] Figure 7 is a flowchart showing a method 300 of treating a patient having an occluded vessel. The method can include delivering a clot engagement frame positioned within a microcatheter 310; delivering a hypotube containing a distal embolic protection system with the clot engagement frame to the occluded vessel 320; deploying the clot engagement frame to contact at least a portion of the clot 330; passing the hypotube through the clot 340; advancing the microcatheter over a proximal portion of the clot engagement frame, thereby clamping the clot 350; deploying the distal embolic protection system 360; and withdrawing the engagement frame, the distal embolic protection system, and the clot from the patient 390.

[0030] In the method 300, the clot engagement portion can at least partially surround the hypotube in a helical configuration. The method 300 can also include withdrawing the clot engagement frame and the distal embolic protection system into the microcatheter and removing the clot engagement frame, the distal embolic protection system, and the clot from the patient. The method 300 can also include withdrawing the clot, the clot engagement frame, and the distal embolic protection system together. The method 300 can also include clamping the clot with an outer surface of the hypotube 370. The method 300 can also include capturing clot fragments with the distal embolic protection system 380.

[0031] Figure 8is a flowchart showing a method 400 of treating a patient having an occluded blood vessel. The occlusion can include a clot. The method 400 can involve: delivering a device 410 through a microcatheter, the device having a stentriever and a pull wire leading to the occluded blood vessel; deploying the stentriever to contact at least a portion of the clot such that a proximal helical portion of the stentriever forms a helix and a distal cylindrical portion of the stentriever forms a cylindrical body 420; pinching at least a portion of the clot with the helical portion of the stentriever 430; retracting the pull wire to cause the cylindrical portion of the stentriever to radially expand 440; withdrawing the microcatheter and the device from the blood vessel together 450; and removing the device, the microcatheter, and the clot from the patient 470.

[0032] The step of pinching at least a portion of the clot with the helical portion 430 can also include moving a first portion of the helical portion proximally toward the microcatheter, thereby causing a second portion of the helical portion to collapse and pinch the clot. The method 400 can also include collecting at least a portion of the clot within a distal cone of the stentriever 460. The step of collecting at least a portion of the clot within the distal cone 460 can also include retracting the pull wire to cause the distal cone to radially expand. The method 400 can also include positioning the device such that at least a portion of the helical segment encircles the pull wire.

[0033] The description contained herein is exemplary of implementations of the application, and is not intended to limit the scope, applicability or configuration of the application in any way. Modifications can occur to one of ordinary skill in the art upon reading the following disclosure and such modifications are intended to fall within the scope of the following claims.

Claims

1. A clot removal device for removing a clot from a blood vessel of a body, the clot removal device delivered to the blood vessel via a catheter and comprising: a pull wire; and a stentriever comprising a proximal helical section and a distal cylindrical body section, the distal cylindrical body section configured to expand from a collapsed delivery configuration to a clamping configuration and to an expanded configuration, in the collapsed delivery configuration, the stentriever and the pull wire are inside the catheter, in the clamping configuration, a portion of the pull wire and the stentriever are outside the catheter, and the stentriever has a first diameter, and in the expanded configuration, a proximal end of the clot contacts a distal end of the catheter, and upon movement of the pull wire relative to the stentriever, the stentriever moves to a second diameter.

2. The device of claim 1, wherein upon proximal retraction of the pull wire relative to the stentriever, a diameter of the cylindrical body section expands radially to be greater than a diameter of the cylindrical body section in the clamping configuration.

3. The device of claim 1, wherein the pull wire is attached to the stentriever proximate a distal end of the stentriever.

4. The device of claim 1, wherein at least a portion of the helical section encircles the pull wire. ​

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