Patent Publication Number: US-2022218370-A1

Title: Systems and methods for a dual elongated member clot retrieval apparatus

Description:
FIELD 
     The present disclosure generally relates to devices and methods for removing blockages from blood vessels during intravascular medical treatments. 
     BACKGROUND 
     Clot retrieval devices are used in mechanical thrombectomy for endovascular intervention, often in cases where patients are suffering from conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). Acute obstructions may include clot, misplaced devices, migrated devices, large emboli, and the like. Thromboembolism occurs when part or all of a thrombus breaks away from the blood vessel wall. This clot (now called an embolus) is then carried in the direction of blood flow. An ischemic stroke may result if the clot lodges in the cerebral vasculature. A pulmonary embolism may result if the clot originates in the venous system or in the right side of the heart and lodges in a pulmonary artery or branch thereof. Clots may also develop and block vessels locally without being released in the form of an embolus—this mechanism is common in the formation of coronary blockages. There are significant challenges associated with designing clot removal devices that can deliver high levels of performance. First, there are a number of access challenges that make it difficult to deliver devices. In cases where access involves navigating the aortic arch (such as coronary or cerebral blockages) the configuration of the arch in some patients makes it difficult to position a guide catheter. These difficult arch configurations are classified as either type 2 or type 3 aortic arches with type 3 arches presenting the most difficulty. 
     The tortuosity challenge is even more severe in the arteries approaching the brain. For example it is not unusual at the distal end of the internal carotid artery that the device will have to navigate a vessel segment with a 180° bend, a 90° bend and a 360° bend in quick succession over a few centimeters of vessel. In the case of pulmonary embolisms, access is through the venous system and then through the right atrium and ventricle of the heart. The right ventricular outflow tract and pulmonary arteries are delicate vessels that can easily be damaged by inflexible or high-profile devices. For these reasons it is desirable that the clot retrieval device be compatible with as low profile and flexible a guide catheter as possible. 
     Second, the vasculature in the area in which the clot may be lodged is often fragile and delicate. For example neurovascular vessels are more fragile than similarly sized vessels in other parts of the body and are in a soft tissue bed. Excessive tensile forces applied on these vessels could result in perforations and hemorrhage. Pulmonary vessels are larger than those of the cerebral vasculature, but are also delicate in nature, particularly those more distal vessels. 
     Third, the clot may comprise any of a range of morphologies and consistencies. Long strands of softer clot material may tend to lodge at bifurcations or trifurcations, resulting in multiple vessels being simultaneously occluded over significant lengths. More mature and organized clot material is likely to be less compressible than softer fresher clot, and under the action of blood pressure it may distend the compliant vessel in which it is lodged. Furthermore, the inventors have discovered that the properties of the clot may be significantly changed by the action of the devices interacting with it. In particular, compression of a blood clot causes dehydration of the clot and results in a dramatic increase in both clot stiffness and coefficient of friction. 
     The challenges described above need to be overcome for any devices to provide a high level of success in removing clot and restoring flow. Existing devices do not adequately address these challenges, particularly those challenges associated with vessel trauma and clot properties. 
     SUMMARY 
     It is an object of the present design to provide devices and methods to meet the above-stated needs. It is therefore desirable for a clot retrieval device to remove clot from cerebral arteries in patients suffering AIS, from coronary native or graft vessels in patients suffering from MI, and from pulmonary arteries in patients suffering from PE and from other peripheral arterial and venous vessels in which clot is causing an occlusion. 
     In some examples, the device includes pinch features configured for placement proximate an occlusion (e.g., in the mid internal carotid artery (ICA)). The device can be configured to reperfuse a vessel and/or remove a clot that has a fibrin core. In some examples, the fibrin core can be in a mid- or distal-position in the clot surrounded by relatively soft thrombus. 
     In some examples, the device can be configured to remove a clot in the M1 bifurcation. 
     In some examples, the device can be configured to remove a clot in the M2 bifurcation. 
     In some examples, a method for manufacturing a clot retrieval device can comprise the steps of: patterning a first predetermined pattern on a first tube to form an outer cage, the outer cage comprising an outer diameter, patterning a second predetermined pattern on a second tube to form an inner cage comprising an inner flow channel, and positioning the inner cage concentrically within the outer cage. Additionally, the clot retrieval device can comprise an expanded configuration with a diameter greater than an inner diameter of a microcatheter. 
     In some examples, an outer diameter of the first tube can approximately equal to the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under, around, about, or the like a clot or to improve vessel wall apposition when compared to an outer cage of a smaller diameter shapeset to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     In some examples, an outer diameter of the first tube can be greater than the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under, around, about, or the like a clot or to improve vessel wall apposition when compared to an outer cage of a smaller diameter shapeset to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     In some examples, the outer cage can be patterned such that it comprises a ring of eight struts. 
     In some examples, the inner cage can be patterned such that it comprises a ring of four struts configured to pinch a portion of a clot. 
     In some examples, the method can further comprise the steps of attaching a first radiopaque marker at a distal end of the outer cage and attaching a second radiopaque marker at a proximal end of the outer cage. 
     In some examples, the method can further comprise the steps of attaching a first elongated member to a proximal end of the outer cage, the first elongated member configured to move the outer cage between delivery and expanded configurations, and attaching a second elongated member to a proximal end of the inner cage, the second elongated member configured to move the inner cage between delivery and expanded configurations. 
     In some examples, the second elongated member can be a wire. 
     In some examples, the first elongated member can be a tube. 
     In some examples, the first elongated member can comprise a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the first elongated member can comprise a variable stiffness profile therealong, a proximal end of the first elongated member being stiffer than a distal end of the first elongated member. 
     In some examples, the second elongated member can be comprise a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the second elongated member can comprise a variable stiffness profile therealong, a proximal end of the second elongated member being stiffer than a distal end of the second elongated member. 
     In some examples, the method can further comprise attaching the second elongated member comprising, attaching a distal end of the second elongated member to a proximal end of a receptacle, attaching the proximal end of the inner cage within a cavity of the receptacle, and wherein the second elongated member can be slidable within a lumen of the first elongated member. 
     In some examples, the receptacle can further comprise a step within the cavity to mitigate over insertion of a proximal end of the inner cage. 
     In some examples, the method can further comprise the steps of patterning a third pre-determined pattern on the first elongated member to achieve a desired stiffness profile along the first elongated member. 
     In some examples, the third pre-determined pattern can comprise one or more of a spiral pattern, one or more interrupted spiral patterns, or one or more radial cut patterns. 
     In some examples, the first and second elongated member can be within separate lumens within the microcatheter. 
     In some examples, the method can further comprise the steps of uncoupling the first and second elongated members, and forwarding, proximally, the microcatheter over the inner cage causing cells of the inner cage to collapse on the clot exerting additional pressure on that portion of the clot or by causing the clot to become engaged between the distal end of the microcatheter and a cell of the inner cage. 
     In some examples, the method can further comprise the steps of coupling, using a clip comprising c-shaped features, the first and second elongated members by: attaching, using the c-shaped features, the proximal end of the first and second elongated members respectively, and sliding, distally or proximally, the first and second elongated member in unison. 
     In some examples, a method for removing a clot can comprise the steps of: locating a microcatheter proximate a clot within a vessel wall, retracting the microcatheter in a proximal direction such that an outer cage and an inner cage within a lumen of the microcatheter expand to about the vessel wall and engage with a portion of the clot, retracting, in a proximal direction, a first elongated member in communication with the inner cage or a second elongated member in communication with the outer cage, such that distance between adjacent struts of the inner cage or struts of the outer cage is reduced exerting pressure on the portion of the clot engaged with inner struts or outer struts, thereby pinching the clot, and forwarding, in a distal direction, the microcatheter over one of the first or a second elongated member. Additionally, forwarding the microcatheter pinches a portion of the clot by causing cells of the inner cage to collapse on the clot exerting additional pressure on that portion of the clot or by causing the clot to become engaged between the distal end of the microcatheter and a cell of the inner cage. 
     In some examples, the method can further comprise retracting the microcatheter, the first and second elongated members, the inner and outer cage, and the clot from the vessel wall. 
     In some examples, the outer cage can be patterned such that it comprises a ring of eight struts. 
     In some examples, the inner cage can be patterned such that it comprises a ring of four struts configured to pinch a portion of the clot. 
     In some examples, locating the microcatheter proximate the clot can further comprise: coupling, using a clip comprising c-shaped features, the first and second elongated members by: attaching, using the c-shaped features, a proximal end of the first and second elongated members respectively, and sliding the microcatheter and the first and second elongated member in unison towards and proximate to the clot. 
     In some examples, retracting the first elongated member in communication with the inner cage can further comprise: uncoupling the first and second elongated members from one another such that the first elongated member can be retracted independently of the second elongated member. 
     In some examples, the second elongated member can be a tube. 
     In some examples, the first elongated member can be a wire. 
     In some examples, the first and second elongated members can be within separate lumens of first and second jackets within the microcatheter. 
     In some examples, the first elongated member can comprise a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the first elongated member can comprise a variable stiffness profile therealong, a proximal end of the first elongated member being stiffer than a distal end of the first elongated member. 
     In some examples, the second elongated member comprises a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the second elongated member can comprise a variable stiffness profile therealong, a proximal end of the second elongated member being stiffer than a distal end of the second elongated member. 
     In some examples, retracting the first elongated member in communication with the inner cage can further comprise: sliding, in a proximal or distal direction, the first elongated member within a lumen of the second elongated member. 
     In some examples, a third pre-determined pattern can be patterned on the second elongated member to achieve a desired stiffness profile along the second elongated member. 
     In some examples, the third pre-determined pattern can comprise one or more of a spiral pattern, one or more interrupted spiral patterns, or one or more radial cut patterns. 
     In some examples, clot retrieval device can comprise an outer cage, an inner cage concentrically positioned within the outer cage, a first elongated member in communication with the outer cage, and a second elongated member in communication with the inner cage. 
     In some examples, an outer diameter of the outer cage can be approximately equal to the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under, around, about, or the like a clot or to improve vessel wall apposition when compared to an outer cage of a smaller diameter shape set to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     In some examples, an outer diameter of the outer cage can be greater than the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under, around, about, or the like a clot or to improve vessel wall apposition when compared to an outer cage of a smaller diameter shape set to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     In some examples, the outer cage can be patterned such that it comprises a ring of eight struts. 
     In some examples, the inner cage can be patterned such that it comprises a ring of four struts configured to pinch a portion of a clot. 
     In some examples, the device can further comprise a first radiopaque marker at a distal end of the outer cage, and a second radiopaque marker at a proximal end of the outer cage. 
     In some examples, the device can further comprise a clip comprising c-shaped features at each end of the clip, each feature configured to receive one of: the first elongated member or the second elongated member, the clip configured to couple the first and second elongated member when attached. 
     In some examples, the device can further comprise the first elongated member attached to a proximal end of the outer cage, the first elongated member configured to move the outer cage between delivery and expanded configurations, and the second elongated member attached to a proximal end of the inner cage, the second elongated member configured to move the inner cage between delivery and expanded configurations. 
     In some examples, the second elongated member can be a wire. 
     In some examples, the first elongated member can be a tube. 
     In some examples, the first elongated member can comprise a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the first elongated member can comprise a variable stiffness profile therealong, a proximal end of the first elongated member being stiffer than a distal end of the first elongated member. 
     In some examples, the second elongated member can comprise a first plurality of segments such that each segment of the plurality comprising decreasing respective outer diameters such that a taper can be formed and the second elongated member can comprise a variable stiffness profile therealong, a proximal end of the second elongated member being stiffer than a distal end of the second elongated member. 
     In some examples, the device can further comprise a distal end of the second elongated member attached to a proximal end of a receptacle, the proximal end of the inner cage attached within a cavity of the receptacle, and wherein the second elongated member can be slidable within a lumen of the first elongated member. 
     In some examples, the receptacle can further comprise a step within the cavity to reduce over insertion of a proximal end of the inner cage. 
     In some examples, the device can further comprise a pre-determined pattern on the first elongated member to achieve a desired stiffness profile along the first elongated member. 
     In some examples, the pre-determined pattern can comprise one or more of a spiral pattern, one or more interrupted spiral patterns, or one or more radial cut patterns. 
     In some examples, the first and second elongated member are within respective lumens of a first and second lubricated elongated member jackets within a microcatheter. 
     Other aspects and features of the present disclosure will become apparent to those of ordinary skill in the art, upon reviewing the following detailed description in conjunction with the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and further aspects of this disclosure are further discussed with the following description of the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the disclosure. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation. It is expected that those of skill in the art can conceive of and combining elements from multiple figures to better suit the needs of the user. 
         FIG. 1A  illustrated an example clot retrieval device in an expanded configuration. 
         FIG. 1B  illustrates a cross-section of an example receptacle. 
         FIG. 1C  illustrates an example clot retrieval device in a delivery configuration. 
         FIG. 1D  illustrates a plan view of an example receptacle. 
         FIG. 1E  illustrates a plan view of an example clot retrieval device. 
         FIGS. 1F-1H  illustrate example predetermined patterns disposed on an elongated member. 
         FIG. 1I  illustrates an example clot retrieval device in a deployed configuration within a vessel and proximate a clot. 
         FIG. 1J  illustrates an example clot retrieval device in a pinched configuration within the vessel and in communication with the clot. 
         FIG. 1K  illustrates a cut view of an example clot retrieval device. 
         FIGS. 2A-2C  illustrates an example clot retrieval device in an expanded configuration. 
         FIG. 2D  illustrates an example clot retrieval device in a delivery configuration. 
         FIG. 2E  illustrates an example cross-section of an example clot retrieval device. 
         FIGS. 2F-2G  illustrate example cross-sections of an example clot retrieval device. 
         FIG. 2H  illustrates an example clot retrieval device in a deployed configuration within a vessel and proximate a clot. 
         FIG. 2I  illustrates an example clot retrieval device in a pinched configuration within the vessel and in communication with the clot. 
         FIG. 2J  illustrates a cut view of an example clot retrieval device. 
         FIG. 2K  illustrates an example clip of an example clot retrieval device. 
         FIG. 3  is a flowchart depicting an assembly of an example clot retrieval device. 
         FIG. 4  is a flowchart depicting operation an example clot retrieval device. 
     
    
    
     DETAILED DESCRIPTION 
     Specific examples of the present disclosure are now described in detail with reference to the Figures, where identical reference numbers indicate elements which are functionally similar or identical. The examples address many of the deficiencies associated with traditional catheters, such as inefficient clot removal and inaccurate deployment of catheters to a target site. 
     Accessing the various vessels within the vascular, whether they are coronary, pulmonary, or cerebral, involves well-known procedural steps and the use of a number of conventional, commercially available accessory products. These products, such as angiographic materials and guidewires are widely used in laboratory and medical procedures. When these products are employed in conjunction with the system and methods of this disclosure in the description below, their function and exact constitution are not described in detail. 
     The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Although the description of the disclosure is in many cases in the context of treatment of intracranial arteries, the disclosure may also be used in other body passageways as previously described. 
     It will be apparent from the foregoing description that, while particular examples of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. For example, while the examples described herein refer to particular features, the disclosure includes examples having different combinations of features. The disclosure also includes examples that do not include all of the specific features described. Specific examples of the present disclosure are now described in detail with reference to the figures, wherein identical reference numbers indicate identical or functionality similar elements. The terms “distal” or “proximal” are used in the following description with respect to a position or direction relative to the treating physician. “Distal” or “distally” are a position distant from or in a direction away from the physician. “Proximal” or “proximally” or “proximate” are a position near or in a direction toward the physician. 
     Accessing cerebral, coronary and pulmonary vessels involves the use of a number of commercially available products and conventional procedural steps. Access products such as guidewires, guide catheters, angiographic catheters and microcatheters are described elsewhere and are regularly used in catheter lab procedures. It is assumed in the descriptions below that these products and methods are employed in conjunction with the device and methods of this disclosure and do not need to be described in detail. 
     The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. Although the description of the disclosure is in many cases in the context of treatment of intracranial arteries, the disclosure may also be used in other body passageways as previously described. 
     A common theme across many of the disclosed designs is a multi-layer construction in which the device in certain instances can include an outer cage within which, at times, can include an inner cage, both cages being directly or indirectly connected to one or more elongated members.  FIG. 1A  depicts an example clot retrieval device  100  in an expanded configuration including a first position. The device  100  can include an outer cage  102 , an inner cage  108 , a receptacle  116 , a first elongated member  114 , a second elongated member  118 , and a microcatheter  120 . The microcatheter  120  can include a lumen  122  including an inner diameter ID 1 . The inner diameter ID 1  can be approximately 0.021 inches. Alternatively, the inner diameter ID 1  can be approximately 0.5 mm. 
     Additionally, the device  100  can include a proximal radiopaque band  128   a  and/or a distal radiopaque band  128   b.  In the expanded configuration, the outer cage  102  can expand to an outer diameter OD 1  and can be outside the lumen  122  of the microcatheter  120 . The outer diameter OD 1  can be approximately 0.6 mm, 2 mm, 4 mm, or 6.5 mm. Alternatively, the outer diameter OD 1  can be between approximately 0.6 mm and 6.5 mm. Alternatively, the outer diameter OD 1  can be between approximately 2 mm and 6.5 mm. Alternatively, the outer diameter OD 1  can be proportional to an inner diameter ID 1  of the microcatheter  120 . As an example, the outer diameter OD 1  can be two times greater than the inner diameter ID 1 , for example, an inner diameter ID 1  of approximately 0.5 mm would result in an outer diameter OD 1  of approximately 1 mm. In this manner, the outer diameter OD 1  can be approximately 1 times greater, 4 times greater, 8 times greater, or 13 times greater than the inner diameter ID 1 . Alternatively, the outer diameter OD 1  can be between approximately 4 to 13 times greater than the inner diameter ID 1 . Additionally, in the expanded configuration, the inner cage  108  can be outside the lumen  122  of the microcatheter  120 . 
     The outer cage  102  can include a proximal end  104 , a distal end  106 , and an outer diameter OD 1 . The outer cage  102  can be made of a network of outer struts  103 . The proximal end  104  of the outer cage  102  can be configured to attach to a distal end  113   a  of the first elongated member  114 . In the expanded configuration, the proximal end  104  of the outer cage  102  can be distal of a distal end  124  of the microcatheter  120 . In a delivery configuration, as described in detail below, the distal end  106  of the outer cage  102  can be proximal of the distal end  124  of the microcatheter  120 . The outer cage  102  can transition between the expanded configuration and the delivery configuration by sliding a lumen  122  of the microcatheter  120  in a proximal or distal direction over the outer cage  102 , thereby causing the outer cage  102  to expand to the outer diameter OD 1 , and the inner cage to expand as well. Additionally or alternatively, the network of outer struts  103  of the outer cage  102  can include a pre-determined pattern disposed thereon including eight struts radially distributed, uniformly or non-uniformly, forming a ring-like pattern as discussed in detail below. However, greater or fewer struts can be included as needed or required. 
     The outer cage  102  can be desirably made from a biocompatible material capable of recovering its shape automatically once released from a highly strained delivery configuration. By way example and without limitation, the outer cage  102  with an outer diameter OD 1  of approximately 6.5 mm is collapsed radially to be inserted within the lumen  122  of the microcatheter  120  including, for example, an inner diameter ID 1  of approximately 0.5 mm, the outer cage  102  would experience a compressive strain of approximately 92%. As another example, the outer cage  102  with an outer diameter OD 1  of approximately 2 mm is collapsed radially to be inserted within the lumen  122  of the microcatheter  120  including, for example, an inner diameter ID 1  of approximately 0.5 mm, the outer cage  102  would experience a compressive strain of approximately 75%. Thus, “a highly strained delivery configuration” as that term is used in this disclosure, can be one where the outer cage  102  experiences a compressive strain between approximately 75% and 92%. However, other ranges that correspond to a highly strained configuration are contemplated as needed or required. 
     In some examples, a superelastic material memory alloy such as Nitinol, or a biocompatible alloy of similar properties. can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a network of struts and connecting elements. This network can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements (e.g., Platinum, tantalum, etc.) or through a variety of other coatings or marker bands. 
     The inner cage  108  can include a proximal end  110 , a distal end  112 , and a network of inner struts  109 . The inner cage  108  can be substantially tubular and concentrically positioned within the outer cage  102  to form a flow channel  108   a.  The flow channel  108   a  can be configured to permit fluid flow between the proximal end  104  and the distal end  106  of the outer cage  102 . Additionally or alternatively, the flow channel  108   a  can be configured to permit fluid flow between the proximal end  110  and the distal end  112  of the inner cage  108 . Additionally or alternatively, the network of inner struts  109  of the inner cage  108  can include a pre-determined pattern disposed thereon including four struts which can be uniformly or non-uniformly distributed radially to form a ring-like pattern as discussed below. However, greater or fewer struts can be included as needed or required. 
     Two or more inner struts in the network of inner struts  109  in communication, either directly or indirectly, with one another can be configured to form a pinching cell  109   a  (e.g., a cell). The network of inner struts  109  can be configured to tweeze a portion of a clot as discussed below in detail. As discussed herein, the term “tweeze” or “tweezing” is intended to refer to the sheathing of the pinching cells that causes respective struts to come together and tweeze or grip at least a portion of clot. In this respect, while the numbers of struts in a respective cell need not be limited, at least two strut surfaces must be included so as to tweeze corresponding clot material. The inner cage  108  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy, such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a network of struts and connecting elements. This network can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements (e.g., Platinum, tantalum etc.) or through a variety of other coatings or marker bands. 
     Turning to  FIG. 1B , the receptacle  116  can include a proximal end  116   a  including an attachment face  116   e,  a cavity  116   b  including and opening  116   d,  and a step  116   c  located within the cavity  116   b  and having an inner diameter ID 3 . The cavity  116   b  can be configured to receive the proximal end  110  of the inner cage  108 . The proximal end  110  of the inner cage  108  can be attached to the cavity  116   b  of the receptacle  116 . Alternatively, the proximal end  110  of the inner cage  108  can be attached to the step  116   c  of the receptacle  116 . The proximal end  110  of the inner cage  108  can be attached using one or more welds. The step  116   c  can prevent over-insertion of the proximal end  110  of the inner cage  108 . The receptacle can be substantially tubular and  116  can be constructed of memory alloy, such as Nitinol, or another biocompatible metal. Additionally or alternatively, the attachment face  116   e  can be configured to attach to the distal end  119   a  of the second elongated member  118 . 
     Turning back to  FIG. 1A , the first elongated member  114  can include a distal end  113   a,  a proximal end  113   b,  and a lumen  115 . The distal end  113   a  of the first elongated member  114  can be attached to the proximal end  104  of the outer cage  102  and configured to move the outer cage  102 . The proximal end  104  of the outer cage  102  can be attached using one or more welds. The first elongated member  114  can be constructed from nitinol or another shape-memory alloy. The first elongated member  114  can have one or more pre-determined patterns, for example, one or more of a spiral pattern, one or more interrupted spiral patterns, or one or more radial cut patterns, disposed thereon to provide a variable stiffness profile therealong as discussed below. Additionally or alternatively, the first elongated member  114  can be substantially tubular, and can configured to slide in a distal or proximal direction within the lumen  122  of the microcatheter  120 . Additionally or alternatively, the first elongated member  114  can be configured to cause the second elongated member  118  and the receptacle  116 , to slide in a distal or proximal direction within the lumen  115  of the first elongated member  114 . Additionally or alternatively, the first elongated member  114  can include a taper to provide a variable stiffness profile therealong as discussed in detail below. The first elongated member  114  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy, such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and can be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     The second elongated member  118  can include a distal end  119   a  and a proximal end  119   b.  The distal end  119   b  of the second elongated member  118  can be configured to attach to the proximal end  116   a  of the receptacle  116 . Additionally or alternatively, the second elongated member can  118  be a wire. Additionally or alternatively, the second elongated member  118  can be a solid shaft and substantially cylindrical. Additionally or alternatively, the second elongated member  118  can be a hollow shaft including a lumen and can be substantially tubular. Additionally or alternatively, the second elongated member  118  can be constructed from nitinol or another shape-memory alloy. Additionally or alternatively, the second elongated member  118  can include a taper to provide a variable stiffness profile therealong as discussed in detail below. The second elongated member  118  can have one or more pre-determined patterns, for example, one or more of a spiral pattern, one or more interrupted spiral patterns, or one or more radial cut patterns, disposed thereon to provide a variable stiffness profile therealong as discussed below. 
     Additionally or alternatively, the second elongated member  118  can be configured to slide in a distal or proximal direction within the lumen  115  of the first elongated member  114 . This can be advantageous as it removes the need to include a PEBAX jacket on the second elongated member  118  and prevents damage to vessels as a result of the “cheese-wire” effect. Additionally or alternatively, the receptacle  116  can be configured to slide in a distal or proximal direction within the lumen  115 . The second elongated member  118  can be attached to the receptacle  116  as discussed above, and sliding the second elongated member  118  in a proximal or distal direction can cause the receptacle  116  to slide in a proximal or distal direction within the lumen  115  of the first elongated member  114 . Additionally or alternatively, movement of the second elongated member  118  in a distal or proximal direction can cause movement of the inner cage  108  in a distal and/or proximal direction, because, as discussed above, the proximal end  110  of the inner cage  108  can be attached to the receptacle  116 , thereby transferring the movement of the second elongated member  118  to the inner cage  108 , via receptacle  116 . The second elongated member  118  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     The microcatheter  120  can include a lumen,  122 , and a distal end  124 . The inner diameter ID 1  of the microcatheter  120  can be dimensioned to slidably position within the lumen  122  at least the first elongated member  114 , and the outer cage  102 . Additionally, the inner cage  108  can be configured to slide within the lumen  122 . The second elongate member  118  can be configured to slide within the lumen  122 . 
     The proximal radiopaque band  128   a  can be positioned at the proximal end  104  of the outer cage  102 . Additionally or alternatively, the proximal radiopaque band  128   a  can be positioned at the proximal end  110  of the inner cage  108 . The proximal radiopaque band  128   a  can be constructed of platinum or other radiopaque materials. The proximal radiopaque band  128   a  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying or through a variety of other coatings or marker bands. 
     The distal radiopaque band  128   b  can be positioned at the distal end  106  of the outer cage  102 . Additionally or alternatively, the distal radiopaque band  128   b  can be positioned at the distal end  112  of the inner cage  108 . The distal radiopaque band  128   b  can be constructed of platinum or other radiopaque materials. The distal radiopaque band  128   b  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
       FIG. 1C  depicts device  100  in a delivery configuration including a second position. In the delivery configuration, the device  100  can be outside of a patient ready for delivery, and the outer cage  102  can be within the lumen  122  of the microcatheter  120 , and can include a diameter substantially similar to the inner diameter ID 1  of the microcatheter  120 . Alternatively, in the delivery configuration, at least a portion of the device  100  can be within a vessel of the patient. Additionally, in the delivery configuration, the distal end  106  of the outer cage  102  and the distal end  112  of the inner cage  108  can be within the lumen  122  of the microcatheter  120  including an inner diameter ID 1 . The inner diameter ID 1  of the microcatheter  120  can be less than the outer diameter OD 1  of the outer cage  102  in the expanded configuration. Additionally, the distal radiopaque band  128   b  can be within the lumen  122 . 
       FIG. 1D  depicts a front plan cross-section of a clot retrieval device  100 . This view depicts various aspects of the receptacle  116  in detail. The receptacle  116  can include the opening  116   d  including an inner diameter ID 3 . The receptacle  116  can include the cavity  116   b  including an inner diameter ID 3  for at least a portion of the cavity  116   b.  The receptacle  116  can be positioned within the lumen  115  of the first elongated member  114 . The first elongated member  114  can include an inner diameter ID 2  including a dimension greater than the inner diameter ID 3  of the opening  116   d.  but less than the inner diameter ID 1  of the microcatheter  120 . The step  116   c  can be disposed within the cavity  116   b  of the receptacle  116 . To prevent over-insertion of the proximal end  110  of the inner cage  108 , the step  116   c  reduces the inner diameter ID 3  of the cavity  116   b,  to an inner diameter ID 4 , thereby preventing the proximal end  110  of the inner cage  108  from being welded to the proximal end  116   a  of the receptacle  116 . The proximal end  110  of the inner cage  108  can be attached to the cavity  116   b  of the receptacle  116 . Alternatively, the proximal end  110  of the inner cage  108  can be attached to the step  116   c  of the receptacle  116 . The proximal end  110  of the inner cage  108  can be attached using one or more welds. 
       FIG. 1E  depicts a cross-section of the outer cage  102  including the network of outer struts  103  and the inner cage  108  including the network of inner struts  109  while in the delivery position. Additionally or alternatively, the network of outer struts  103  can be patterned to include between six and ten struts, which can be uniformly or non-uniformly distributed around a centerline of the outer cage  102 . Additionally or alternatively, the network of inner struts  109  can be patterned to include between two and six struts, which can be uniformly or non-uniformly distributed around a centerline of the inner cage  108 . 
       FIG. 1F-1H  depict examples for pre-determined patterns disposed on the first elongated member  114 .  FIG. 1F  depicts the first elongated member  114  including a spiral cut  126   a  disposed thereon. The spiral cut  126   a  can be a helix having a uniform spacing between each revolution of the helix and/or a uniform helix angle forming the uniform spacing between each revolution of the helix along a length of the first elongated member  114 . Alternatively, the spiral cut  126   a  can be a helix having a non-uniform spacing between each revolution of the helix and/or a non-uniform helix angle forming the non-uniform spacing between each revolution of the helix along a length of the first elongated member  114 , thereby resulting in variable stiffness of the first elongated member  114  along the length of the first elongated member  114 . Additionally, the second elongate member  118 , can include a spiral cut, such as spiral cut  126   a,  disposed thereon.  FIG. 1G  depicts the first elongated member  114  including an interrupted spiral pattern  126   b  disposed thereon. The interrupted spiral pattern  126   b  can be a helix cut having a uniform spacing between each revolution of the helix and/or a uniform helix angle forming the uniform spacing between each revolution of the helix along a length of the first elongated member  114 . Alternatively, the interrupted spiral pattern  126   b  can be a helix cut including a non-uniform spacing between each revolution of the helix and/or a non-uniform helix angle forming the non-uniform spacing between each revolution of the helix along a length of the first elongated member  114 , thereby resulting in variable stiffness of the first elongated member  114  along the length of the first elongated member  114 . Additionally, the second elongate member  118 , can include an interrupted spiral pattern, such as interrupted spiral pattern  126   b,  disposed thereon. The helix (or helical) cut need not be a continuous cut, said differently, there can be a plurality of cuts interrupted, or separated, by material of the first elongated member  114 .  FIG. 1H  depicts the first elongated member  114  including a radial cut pattern disposed thereon. The radial pattern  126   c  can be a plurality of cuts perpendicular to the length of the first elongated member  114  and repeated uniformly along a length of the first elongated member  114 . Alternatively, the radial pattern  126   c  can be a plurality of cuts perpendicular to the length of the first elongated member  114  and repeated non-uniformly along a length of the first elongated member  114 . Additionally, the second elongate member  118 , can include a radial pattern, such as radial pattern  126   c,  disposed thereon. 
       FIG. 1I  illustrates an example clot retrieval device  100  in a deployed configuration including a third position within a vessel  2  and in communication with a clot  1 . Additionally, in the deployed configuration, the outer cage  102  can be outside (e.g., distal of) the lumen  122  of the microcatheter  120 . Additionally, in the deployed configuration, the inner cage  108  can be outside (e.g., distal of) the lumen  122  of the microcatheter  120 . The retraction of the microcatheter  120  in a proximal direction can deploy the inner cage  108  and the outer cage  102 . As a result, a portion of the clot  1  can be in communication with the outer cage  102  and/or the inner cage  108 . Specifically, the portion of the clot  1  can be in communication with the network of inner struts  109  and/or the network of outer struts  103 . The flow channel  108   a  of the inner cage  108  can allow fluid to flow beyond the clot  1 . The first and second elongated member  114 ,  118  can move independently of each other in a proximal and/or distal direction. Additionally or alternatively, the first and second elongated members  114 ,  118  can be coupled at respective proximal ends  113   b,    119   b  of the first and second elongated members  114 ,  118  such that they move together in a proximal and/or distal direction. 
       FIG. 1J  illustrates an example clot retrieval device  100  in a pinched configuration within the vessel  2  and in communication with the clot  1 . Additionally, in the pinched configuration, a portion of the outer cage  102  can be outside the lumen  122  of the microcatheter  120  and in communication with a portion of the clot  1 . Additionally, in the pinched configuration, a portion of the inner cage  108  can be outside the lumen  122  of the microcatheter  120  and pinching, or tweezing, a portion of the clot  1 . The first and second elongated member  114 ,  118  can move independently of each other in a proximal and/or distal direction. Additionally or alternatively, the first and second elongated members  114 ,  118  can be uncoupled at respective proximal ends  113   b,    119   b  of the first and second elongated members  114 ,  118  such that they move independently. The microcatheter  120  and/or the first elongated member  114  can be forwarded (e.g., resheathed) over the second elongated member  118 . Additionally or alternatively, the microcatheter  120  and/or the first elongated member  114  can be forwarded over the inner cage  108  such that network of inner struts  109 , configured to form pinch cells  109   a,  can pinch a portion of the clot  1 . It can be advantageous for the for the first and second elongated member  114 ,  118  to move independently because the network of outer struts  103  can remain in communication and/or engaged with a portion of the clot  1  while the pinching cells  109   a  of the inner cage  108  can pinch a portion of the clot  1 . 
       FIG. 1K  depicts an example first elongated member  114  and an example second elongated member  118  including a taper. The first elongated member  114  can include a first plurality of segments  114   a,    114   b  such that each segment of the plurality can include increasing respective outer diameters OD 5 , and OD 6  such that the taper can be formed. Additionally or alternatively, increasing corresponding inner diameters of the first plurality of segments  114   a,    114   b  is contemplated. As an example, of outer diameter OD 6  of segment  114   b  is greater than outer diameter OD 5  of segment  114   a,  an inner diameter associated with segment  114   b  can be greater than an inner diameter associated with segment  114   a.  The taper can be continuous, for example, and can include an outer diameter at the proximal end  113   b  of the first elongated member  114  and a smaller outer diameter at the distal end  113   a  of the first elongated member  114 . Additionally or alternatively, a continuous taper for corresponding inner diameters is also contemplated. As an example, the continuous taper for corresponding inner diameters can include an inner diameter at the proximal end  113   b  of the first elongated member  114  and a smaller inner diameter at the distal end  113   a  of the first elongated member  114 . The first elongated member  114  can include a variable stiffness profile therealong, a proximal end  113   b  of the first elongated member  114  being stiffer than a distal end  113   a  of the first elongated member  114 . The second elongated member  118  can include a first plurality of segments  118   a,    118   b,  and  118   c  such that each segment of the plurality can include increasing respective outer diameters OD 2 , OD 3 , and OD 4  such that the taper can be formed. The taper can be continuous, for example, can include an outer diameter at the proximal end  119   b  of the second shaft  118  and a smaller outer diameter at the distal end  119   a  of the second shaft  118 . The second elongated member  118  can include a variable stiffness profile therealong, a proximal end  113   b  of the first elongated member  114  being stiffer than a distal end  113   a  of the first elongated member  114 . Additionally or alternatively, only the second elongated member  118  includes a taper. Additionally or alternatively, only the first elongated member  114  includes a taper. In examples, the first and second elongated members  114 ,  118  include a taper. 
       FIGS. 2A-2C  illustrates an example clot retrieval device  200  in an expanded configuration including a first position, as that configuration has been previously described. The device  200  can include an outer cage  202 , an inner cage  208 , a first elongated member  220 , a second elongated member  216 , a first lubricating jacket  221 , a second lubricating jacket  217 , and a microcatheter  120 . Additionally, the device  200  can include a proximal radiopaque band  134   a  and/or a distal radiopaque band  134   b.    
     The outer cage  202  can include a proximal end  204 , a distal end  206 , and an outer diameter OD 1 . The outer cage  202  can be made of a network of outer struts  203 . The proximal end  204  of the outer cage  202  can be configured to attach to a distal end  218  of the first elongated member  220 . In the expanded configuration, the proximal end  204  of the outer cage  202  can be distal of the distal end  124  of the microcatheter  120 , thereby causing the outer cage  202  to expand to the outer diameter OD 1 , and the inner cage  208  to expand as well. In a delivery configuration, as described in detail below, the distal end  206  of the outer cage  202  can be proximal of a distal end  124  microcatheter  120 . The outer cage  202  can transition between the deployed configuration and the delivery configuration by sliding a lumen  122  of the microcatheter  120  in a proximal or distal direction over the outer cage  202 . Additionally or alternatively, the network of outer struts  203  of the outer cage  202  can include a pre-determined pattern disposed thereon including eight struts distributed, uniformly or non-uniformly, radially forming a ring-like pattern as discussed in detail below. However, greater or fewer struts can be included as needed or required. Turning to  FIGS. 2B and 2C , a c-shaped collar  232  can be disposed at the proximal end  204  of the outer cage  202 . The c-shaped collar  232  can include a lumen  232   a  configured to receive and be in communication with a positioning pin  226  at a distal end  218  of a first elongated member  220 . Additionally, the c-shaped collar  232  can be in communication with the network of outer struts  203 . Additionally, the c-shaped collar  232  can abut a step  222  of the first elongated member  220  such that sliding the first elongated member in a distal direction moves the outer cage  202  in the distal direction. Additionally, sliding the first elongated member  220  in a proximal direction disengages the step  222  from the c-shaped collar  232  and slides the positioning pin  226  from the lumen  232   a  of the c-shaped collar  232  such that the outer cage  202  does not move in the proximal direction. 
     Turning back to  FIG. 2A , the outer cage  202  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory such as Nitinol or a biocompatible metal alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a network of struts and connecting elements. This network can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     The inner cage  208  can include a proximal end  210 , a distal end  212 , and a network of inner struts  209 . The inner cage  208  can be substantially tubular and concentrically positioned within the outer cage  202  to form a flow channel  208   a.  The flow channel  208   a  can be configured to permit fluid flow between the proximal end  204  and the distal end  206  of the outer cage  202 . Additionally or alternatively, the flow channel  208   a  can be configured to permit fluid flow between the proximal end  210  and the distal end  212  of the inner cage  208 . Additionally or alternatively, the network of inner struts  209  of the inner cage  208  can include a pre-determined pattern disposed thereon including four struts which can be uniformly or non-uniformly distributed radially to form a ring-like pattern as discussed below. However, greater or fewer struts can be included as needed or required. Turning to  FIGS. 2B and 2C , a c-shaped collar  230  can be disposed at the proximal end  210  of the inner cage  208 . The c-shaped collar  230  can be attached to a guide pin  228  at a distal end  214  of a second elongated member  216 . Additionally, the c-shaped collar  230  can be in communication with the network of inner struts  209 . Additionally or alternatively, the c-shaped collar  232  can abut a step  224  of the second elongated member  216  such that sliding the second elongated member in a distal or proximal direction moves the inner cage  208  in the respective direction. The c-shaped collar  230  can be welded to the guide pin  228 . Additionally or alternatively, the c-shaped collar can be welded to the step  224 . 
     Turning back to  FIG. 2A , two or more struts in the network of inner struts  209  can be in communication, either directly or indirectly, with one another can be configured to form a pinching cell  209   a  (e.g., a cell). The network of inner struts  209  can be configured to tweeze a portion of a clot as discussed below in detail. As discussed herein, the term “tweeze” or “tweezing” is intended to refer to the sheathing of the pinching cells that causes respective struts to come together and tweeze or grip at least a portion of clot. In this respect, while the numbers of struts in a respective cell need not be limited, at least two strut surfaces must be included so as to tweeze corresponding clot material. The inner cage  208  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties is particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure to create a framework of struts and connecting elements. This framework can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     Turning to  FIGS. 2B-C , the first elongated member  220  can include a distal end  218  and a proximal end  219 . Additionally, at the distal end  218 , the first elongated member  220  can include the step  222  configured to abut with the c-shaped collar  232  of the outer cage  202 . Additionally, the positioning pin  226  disposed distal of the step  222  can be configured to be inserted within the lumen  232   a  of the c-shaped collar  232  of the outer cage  202 . Turning back to  FIG. 2A , the proximal end  218  of the first elongated member  220 , can be configured to receive a clip configured to couple the first elongated member  220  with the second elongated member  216 , such that proximal or distal sliding of the first elongated member  220  or second elongated member  216  results in a respective sliding of the other elongated member, as discussed below. Additionally or alternatively, the first elongated member  220  can include one or more pre-determined patterns, for example, one or more of a spiral pattern (e.g., spiral cut  126   a ), one or more interrupted spiral patterns (e.g., interrupted spiral pattern  126   b ), or one or more radial cut patterns (e.g., radial pattern  126   c ), disposed thereon to provide a variable stiffness profile therealong as discussed below. Additionally or alternatively, the first elongated member  220  can be a wire, a shaft or a tube, and can configured to slide in a distal or proximal direction within the lumen  122  of the microcatheter  120 . The first elongated member  220  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or a biocompatible alloy of similar properties is particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements (e.g., Platinum) or through a variety of other coatings or marker bands. 
     The first lubricating jacket  221  can include a lumen  221   a.  The first elongated member  220  can be configured to slide in a proximal or distal direction within the lumen  221   a  of the first lubricating jacket  221 . The lubrication provided by the first lubricating jacket  221  can be advantageous in reducing friction between the first elongated member  220  and, for example, the lumen  221   a  of the first lubricating jacket  221 . Additionally or alternatively, the first lubricating jacket  221  can isolate at least a portion of the first elongated member  220  from rubbing against the lumen  122  of the microcatheter  120  and/or the second lubricating jacket  217 . The lubricant can be, for example, an elastomer such as PEBAX and/or other suitable lubricants. The first elongated member  220  and the first lubricating jacket  221  can include a substantially circular or elliptical cross-section. Alternatively, the first elongated member  220  and the first lubricating jacket  221  can include a substantially non-symmetric cross-section. Additionally, the first elongated member  220  can be positioned concentrically within the lumen  221   a  of the first lubricating jacket  221 . 
     Turning back to  FIGS. 2B-C . the second elongated member  216  can include a distal end  214  and a proximal end  215 . Additionally, at the distal end  214 , the second elongated member  216  can include the step  224  configured to attach to the c-shaped collar  230  of the inner cage  208 . Additionally, the guiding pin  228  located distal of the step  224  can be configured to attach the c-shaped collar  230  of the inner cage  208 . Turning back to  FIG. 2A , the proximal end  215  of the second elongated member  216 , can be configured to receive a clip configured to couple the second elongated member  216  with the first elongated member  220 , such that proximal or distal sliding of the second elongated member  216  or first elongated member  220  results in a respective sliding of the other elongated member, as discussed below. 
     Additionally or alternatively, the second elongated member  216  can include one or more pre-determined patterns, for example, one or more of a spiral pattern (e.g., spiral cut  126   a ), one or more interrupted spiral patterns (e.g., interrupted spiral pattern  126   b ), or one or more radial cut patterns (e.g., radial pattern  126   c ), disposed thereon to provide a variable stiffness profile therealong as discussed below. Additionally or alternatively, the second elongated member  216  can be a wire, a shaft or a tube, and can configured to slide in a distal or proximal direction within the lumen  122  of the microcatheter  120 . The second elongated member  216  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or a biocompatible metal alloy of similar properties is particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then can be heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     The second lubricating jacket  217  can include a lumen  217   a.  The second elongated member  216  can be configured to side in a proximal or distal direction within the lumen  217   a  of the second lubricating jacket  217 . The lubrication provided by the second lubricating jacket  217  can be advantageous in reducing friction between the second elongated member  216  and, for example, the lumen  217   a  of the second lubricating jacket  217 . Additionally or alternatively, the second lubricating jacket  217  can isolate at least a portion of the second elongated member  216  from rubbing against the lumen  122  of the microcatheter  120  and/or the first lubricating jacket  221 . The lubricant can be, for example, an elastomer such as PEBAX and/or other suitable lubricants. The second elongated member  216  and the second lubricating jacket  217  can include a substantially circular or elliptical cross-section. Alternatively, the second elongated member  216  and the second lubricating jacket  217  can include a substantially non-symmetric cross-section. Additionally, the second elongated member  216  can be positioned concentrically within the lumen  217   a  of the second lubricating jacket  217 . 
     The proximal radiopaque band  234   a  can be positioned at the proximal end  204  of the outer cage  202 . Additionally or alternatively, the proximal radiopaque band  234   a  can be positioned at the proximal end  210  of the inner cage  208 . The proximal radiopaque band  234   a  can be constructed of platinum or other radiopaque materials. The proximal radiopaque band  234   a  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
     The distal radiopaque band  234   b  can be positioned at the distal end  206  of the outer cage  202 . Additionally or alternatively, the distal radiopaque band  234   b  can be positioned at the distal end  212  of the inner cage  208 . The distal radiopaque band  234   b  can be constructed of platinum or other radiopaque materials. The distal radiopaque band  234   b  can be desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material memory alloy such as Nitinol or an alloy of similar properties can be particularly suitable. The material could be in many forms such as wire or strip or sheet or tube. A particularly suitable manufacturing process is to laser cut a Nitinol tube and then heat set and electropolish the resultant structure. This structure can be any of huge range of shapes as disclosed herein and may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. 
       FIG. 2D  illustrates the device  200  in a delivery configuration in a second position, as that configuration has been previously described. the distal end  206  of the outer cage  202  and the distal end  212  of the inner cage  208  can be proximate the distal end  124  of the microcatheter  120  and within the lumen  122  of the microcatheter  120  including an inner diameter ID 1 . Additionally, the distal radiopaque band  128   b  can be within the lumen  122 . The inner diameter ID 1  of the microcatheter  120  can be less than the outer diameter OD 1  of the outer cage  202  in the expanded configuration. In the delivery configuration, the distal end  206  of the outer cage  2020  can be proximal of a distal end  124  microcatheter  120 . The outer cage  202  can transition between the expanded configuration and the delivery configuration by sliding a lumen  122  of the microcatheter  120  in a proximal or distal direction over the outer cage  202 . 
       FIG. 2E  depicts a cross-section of the outer cage  202  including the network of outer struts  203  and the inner cage  208  including the network of inner struts  209  while in the delivery position. Additionally or alternatively, the network of outer struts  203  can be patterned to include between six and ten struts, uniformly or non-uniformly distributed, around a centerline of the outer cage  202 . Additionally or alternatively, the network of inner struts  209  can be patterned to include between two and six struts, which can be uniformly or non-uniformly distributed around a centerline of the inner cage  208 . 
       FIGS. 2F-2G  illustrate example cross-sections of an example clot retrieval device.  FIG. 2F  illustrates an example configuration of the first and second elongated members  220 ,  216  within the lumen  122  of the microcatheter  120 . The first and second elongated members  220 ,  216  can include a substantially circular and/or elliptical cross-section. The first and second lubricating jackets  221 ,  217  can include a substantially circular and/or elliptical cross-section corresponding to the cross-sections of their respective elongated members. The first and second elongated members  220 ,  216  can be concentrically positioned within the first and second lubricating jackets  221 ,  217 , respectively.  FIG. 2G  illustrates an example configuration of the first and second elongated members  220 ,  216  within the lumen  122  of the microcatheter  120 . The first and second elongated members  220 ,  216  can include a substantially horseshoe-shaped and/or an elliptical cross-section. The first and second lubricating jackets  221 ,  217  can include a substantially horseshoe-shaped and/or an elliptical cross-section corresponding to the cross-sections of their respective elongated members. The first and second elongated members  220 ,  216  can be concentrically positioned within the first and second lubricating jackets  221 ,  217 , respectively. 
       FIG. 2H  illustrates an example clot retrieval device  200  in a deployed configuration in a third position within a vessel  2  and in communication with a clot  1 , as that configuration has been previously described. The retraction of the microcatheter  120  in a proximal direction can deploy the inner cage  208  and the outer cage  202 . As a result, a portion of the clot  1  can be in communication with the outer cage  202  and/or the inner cage  208 . Specifically, the portion of the clot  1  can be in communication with the network of inner struts  209  and/or the network of outer struts  203 . The flow channel  208   a  of the inner cage  208  can allow fluid to flow beyond the clot  1 . Additionally or alternatively, the first and second elongated members  220 ,  216  can be coupled at respective proximal ends  219 ,  215  of the first and second elongated members  220 ,  216  such that they move together. A clip  235  can be utilized to couple or decouple the first and second elongated members  220 ,  216 , as will be discussed below. Alternatively, the clip  235  can be removed to decouple the first and second elongated members  220 ,  216 , allowing the first and second elongated member  220 ,  216  to move independently of each other in a proximal and/or distal direction. 
       FIG. 2I  illustrates an example clot retrieval device  200  in a pinched configuration within the vessel  2  and in communication with the clot  1 . Additionally or alternatively, the first and second elongated members  220 ,  216  can be uncoupled at respective proximal ends  219 ,  215  of the first and second elongated members  220 ,  216  such that they move independently. Additionally or alternatively, the microcatheter  120  can be forwarded (e.g., resheathed) over the second elongated member  216  and/or the inner cage  208  such that network of inner struts  209  configured to form pinch cells  209   a  can pinch a portion of the clot  1 . It can be advantageous for the for the first and second elongated member  220 ,  216  to move independently because the network of outer struts  203  can remain in communication and/or engaged with a portion of the clot  1  while the pinching cells  209   a  of the inner cage  208  can pinch a portion of the clot  1 . 
       FIG. 2J  depicts an example first elongated member  220  and an example second elongated member  216  including a taper. The first elongated member  220  can include a first plurality of segments  220   a,    220   b,    220   c  such that each segment of the plurality can include increasing respective outer diameters OD 9 , OD 8 , and OD 7  such that the taper can be formed. The taper can be continuous, for example, can include an outer diameter at the proximal end  219  of the first elongated member  220  and a smaller outer diameter at the distal end  218  of the first elongated member  220 . The first elongated member  220  can include a variable stiffness profile therealong, a proximal end  219  of the first elongated member  220  being stiffer than a distal end  219  of the first elongated member  220 . The second elongated member  216  can include a first plurality of segments  216   a,    216   b,  and  216   c  such that each segment of the plurality can include increasing respective outer diameters OD 12 , OD 11 , and OD 10  such that the taper can be formed. The taper can be continuous, for example, can include an outer diameter at the proximal end  215  of the second shaft  216  and a smaller outer diameter at the distal end  214  of the second shaft  216 . The second elongated member  216  can include a variable stiffness profile therealong, a proximal end  215  of the second elongated member  216  being stiffer than a distal end  214  of the second elongated member  216 . Additionally or alternatively, only the second elongated member  216  includes a taper. Additionally or alternatively, only the first elongated member  220  includes a taper. In examples, the first and second elongated members  220 ,  216  include a taper. 
     In some examples, the first and second lubricating jackets  221 ,  217  can include a plurality of segments including a corresponding inner diameter dimensioned to substantially equal the outer diameters of each corresponding segment of the respective elongated member, thereby forming a taper of the lumen of each respective lubricating jacket. As an example, the lumen  221   a  of first lubricating jacket  221  can include a plurality of segments each including an inner diameter. A first segment of the first lubricating jacket  221  can correspond to the first segment, for example segment  220   a,  of the first elongated member  220  such that the inner diameter of the first segment of the first lubricating jacket  221  can be substantially equal to the outer diameter OD 9 . Alternatively, the first and second lubricating jackets can include respective constant inner diameters. Additionally or alternatively, the constant inner diameter of the first lubricating jacket  221  can be the same as the constant inner diameter of the second lubricating jacket  217 . Additionally or alternatively, the constant inner diameter of the first lubricating jacket  221  can be different from the constant inner diameter of the second lubricating jacket  217 . 
       FIG. 2K  illustrates an example clip  235  of an example clot retrieval device  200 . A clip  235  can include a first and second c-shaped features  236 ,  238  with a connective structure  239  therebetween. The first and second c-clips  236 ,  238  can be configured to receive the first and/or second elongated members  220 ,  216 . Additionally, the first and second c-shaped features  236 ,  238  can be configured to receive the proximal ends  219 ,  215  of the first and/or second elongated members  220 ,  216 . The c-shaped features  236 ,  238  can be made of stainless steel, plastic, and/or other suitable materials. The clip  235  can be configured to couple the first and second elongated members  220 ,  216  when engaged with the first and second c-shaped features  236 ,  238 . The clip  235  can be configured to decouple the first and second elongated members  220 ,  216  when disengaged from the first and second c-shaped features  236 ,  238 . 
       FIG. 3  is a flowchart depicting a method ( 300 ) for assembly of an example clot retrieval device. The method  300  can include, at block  302 , patterning a first predetermined pattern on a first tube to form an outer cage (e.g., outer cage  102 ), the outer cage comprising an outer diameter (e.g., outer diameter OD 1 ). At block  304 , the method  300  can include patterning a second predetermined pattern on a second tube to form an inner cage (e.g., inner cage  108 ) comprising an inner flow channel (e.g., flow channel  108   a ), and at block  304 , can include positioning the inner cage concentrically within the outer cage. Additionally or alternatively, the clot retrieval device (e.g., clot retrieval device  100 ) can include an expanded configuration with the outer diameter greater than an inner diameter (e.g., inner diameter ID 1 ) of a microcatheter (e.g., microcatheter  120 ). 
     Additionally or alternatively, an outer diameter of the first tube can be approximately equal to the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under a clot (e.g., clot  1 ) or to improve vessel wall (e.g., vessel  2 ) apposition when compared to an outer cage of a smaller diameter shape set to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     Additionally or alternatively, an outer diameter of the first tube can be greater than the outer diameter of the clot retrieval device in an expanded configuration, thereby expanding an outer cage to a greater diameter under a clot or to improve vessel wall apposition when compared to an outer cage of a smaller diameter shape set to attain the outer diameter of the clot retrieval device, when both clot retrieval devices have equal radial force. 
     Additionally or alternatively, the network of outer struts  103  of the outer cage  102  can include a pre-determined pattern disposed thereon including eight struts distributed, uniformly or non-uniformly, radially forming a ring-like pattern as discussed in detail below. However, greater or fewer struts can be included as needed or required. Additionally or alternatively, the network of inner struts  109  of the inner cage  108  can include a pre-determined pattern disposed thereon including four struts which can be uniformly or non-uniformly distributed radially to form a ring-like pattern as discussed below. However, greater or fewer struts can be included as needed or required. 
     Additionally or alternatively, the method  300  can include attaching a first radiopaque marker (e.g., distal radiopaque band  128   b ) at a distal end (e.g., distal end  106 ) of the outer cage. Additionally or alternatively, the method  300  can include attaching a second radiopaque marker (e.g., proximal radiopaque marker  128   a ) at a proximal end (e.g., proximal end  104 ) of the outer cage. 
     Additionally or alternatively, the method  300  can include attaching a first elongated member (e.g., first elongated member  114 ) to a proximal end of the outer cage. The first elongated member can be configured to move the outer cage between delivery and expanded configurations. Additionally or alternatively, the method  300  can include attaching a second elongated member (e.g., second elongated member  118 ) to a proximal end of the inner cage. The second elongated member can be configured to move the inner cage between delivery and expanded configurations. Additionally or alternatively, the first elongated member can be a tube. Additionally or alternatively, the second elongated member can be a wire. 
     Additionally or alternatively, the second elongated member can include a first plurality of segments (e.g., the first plurality of segments  114   a,    114   b ) such that each segment of the plurality can include increasing respective outer diameters (e.g., OD 5 , OD 6 ) such that a taper can be formed. Additionally or alternatively, the second elongated member can include a variable stiffness profile therealong, a proximal end (e.g., proximal end  113   b ) of the second elongated member being stiffer than a distal end (e.g., distal end  119   a ) of the second elongated member. Additionally or alternatively, the first and second elongated members can be within separate lumens within the microcatheter. 
     Additionally or alternatively, the method  300  can include attaching a distal end (e.g.,  119   a ) of the second elongated member to a proximal end (e.g., proximal end  116   a ) of a receptacle (e.g., receptacle  116 ). Additionally or alternatively, the method  300  can include attaching the proximal end (e.g., proximal end  110 ) of the inner cage within a cavity (e.g., cavity  116   b ) of the receptacle. Additionally or alternatively, the second elongated member can be slidable within a lumen (e.g., lumen  115 ) of the first elongated member. Additionally or alternatively, the receptacle can include a step (e.g., step  116   c ) within the cavity to prevent over insertion of the proximal end of the inner cage. 
     Additionally or alternatively, the method  300  can include patterning a third pre-determined pattern on the first elongated member to achieve a desired stiffness profile along the first elongated member. Additionally or alternatively, the third pre-determined pattern can include one or more of a spiral pattern (e.g., spiral pattern  126   a ), one or more interrupted spiral patterns (e.g., interrupted spiral patterns  126   b ), or one or more radial cut patterns (e.g., radial cut patterns  126   c ). 
     Additionally or alternatively, the method  300  can include uncoupling the first and second elongated members (e.g., first and second elongated member  216 ,  220 ), and forwarding, proximally, the microcatheter over the inner cage causing cells (e.g., pinching cells  209   a ) of the inner cage to collapse on the clot exerting additional pressure on that portion of the clot or by causing the clot to become engaged between the distal end of the microcatheter and a cell of the inner cage. 
     Additionally or alternatively, the method  300  can include coupling, using a clip (e.g., clip  235 ) comprising c-shaped features (e.g., first and second c-shaped features  236 ,  238 ), the first and second elongated members (e.g., first and second elongated member  216 ,  220 ) by attaching, using the c-shaped features, the proximal end (e.g., proximal ends  215 ,  219 ) of the first and second elongated members respectively, and sliding, distally or proximally, the first and second elongated member in unison. 
       FIG. 4  is a flowchart depicting operation an example clot retrieval device. The method  400  can include, at block  402 , locating a microcatheter (e.g., microcatheter  120 ) proximate a clot (e.g., clot  1 ) within a vessel (e.g., vessel  2 ). At block  404 , the method  400  can include retracting the microcatheter in a proximal direction such that an outer cage (e.g., outer cage  102 ) and an inner cage (e.g., inner cage  108 ) within a lumen (e.g., lumen  122 ) of the microcatheter expand to about the vessel wall and engage with a portion of the clot. At block  406 , the method  400  can include retracting, in a proximal direction, a first elongated member (e.g., second elongated member  118 ) in communication with the inner cage or a second elongated member (e.g., first elongated member  114 ) in communication with the outer cage, such that distance between adjacent struts (e.g., network of inner struts  209 ) of the inner cage or struts (e.g., network of outer struts  103 ) of the outer cage is reduced exerting pressure on the portion of the clot engaged with inner struts or outer struts, thereby pinching the clot. At block  408 , the method  400  can include forwarding, in a distal direction, the microcatheter over one of the first or a second elongated members. Additionally or alternatively, forwarding the microcatheter pinches a portion of the clot by causing cells (e.g., pinching cells  109   a ) of the inner cage to collapse on the clot exerting additional pressure on that portion of the clot or by causing the clot to become engaged between the distal end of the microcatheter and a cell of the inner cage. 
     Additionally or alternatively, the method  400  can include coupling, using a clip (e.g., clip  235 ) including c-shaped features (e.g., first and second c-shaped features  236 ,  238 ), the first and second elongated members by attaching, using the c-shaped features, the proximal end of the first and second elongated members respectively. Additionally, sliding, distally or proximally, the first and second elongated member in unison. 
     Additionally or alternatively, the method  400  can include retracting the microcatheter, the first and second elongated members, the inner and outer cage, and the clot from the vessel wall. Additionally or alternatively, the network of outer struts  103  of the outer cage  102  can include a pre-determined pattern disposed thereon including eight struts distributed uniformly radially forming a ring-like pattern as discussed in detail below. However, greater or fewer struts can be included as needed or required. Additionally or alternatively, the network of inner struts  109  of the inner cage  108  can include a pre-determined pattern disposed thereon including four struts which can be uniformly or non-uniformly distributed radially in to form a ring-like pattern as discussed below. However, greater or fewer struts can be included as needed or required. 
     Additionally or alternatively, retracting the first elongated member in communication with the inner cage can include uncoupling the first and second elongated members from one another such that the first elongated member can be retracted independently of the second elongated member. Additionally or alternatively, the second elongated member can be a tube. Additionally or alternatively, the first elongated member can be a wire. 
     Additionally or alternatively, the first and second elongated members can be within separate lumens (e.g., lumen  221   a  and lumen  217   a ) of first and second jackets (e.g., first and second lubricating jackets  221 ,  217 ) within the microcatheter. Additionally or alternatively, the second elongated member can include a first plurality of segments such that each segment of the plurality can include decreasing respective outer diameters such that a taper is formed and the second elongated member comprises a variable stiffness profile therealong, a proximal end of the second elongated member being stiffer than a distal end of the second elongated member. 
     Additionally or alternatively, retracting the first elongated member in communication with the inner cage further can include sliding, in a proximal or distal direction, the first elongated member within a lumen of the second elongated member. 
     Additionally or alternatively, the third pre-determined pattern can be a spiral cut (e.g., spiral cut  126   a ) can be a helix having a uniform spacing between each revolution of the helix and/or a uniform helix angle forming the uniform spacing between each revolution of the helix along a length of the first or second elongated member. Additionally or alternatively, the spiral cut (e.g., spiral cut  126   a ) can be a helix having non-uniform spacing between each revolution of the helix and/or a non-uniform helix angle forming the non-uniform spacing between each revolution of the helix along a length of the first or second elongated member. Additionally or alternatively, the third pre-determined pattern can be an interrupted spiral pattern (e.g., interrupted spiral pattern  126   b ) disposed thereon. The interrupted spiral pattern can be a helix cut having a uniform spacing between each revolution of the helix and/or a uniform helix angle forming the uniform spacing between each revolution of the helix along a length of the first or second elongated member. 
     Additionally or alternatively, the interrupted spiral pattern can be a helix cut having a non-uniform spacing between each revolution of the helix and/or a non-uniform helix angle forming the non-uniform spacing between each revolution of the helix along a length of the first or second elongated member. The helix cut need not be a continuous cut, said differently, there can be a plurality of cuts interrupted, or separated, by material of the first or second elongated member. Additionally or alternatively, the third pre-determined pattern can be a radial cut pattern (e.g., radial pattern  126   c ) disposed thereon. The radial pattern can be a plurality of cuts perpendicular to the length of the first or second elongated member and repeated uniformly in along a length of the first or second elongated member. Additionally or alternatively, the radial pattern can be a plurality of cuts perpendicular to the length of the first or second elongated member and repeated non-uniformly in along a length of the first or second elongated member. 
     The disclosure is not limited to the examples described, which can be varied in construction and detail. The terms “distal” and “proximal” are used throughout the preceding description and are meant to refer to a positions and directions relative to a treating physician. As such, “distal” or distally” refer to a position distant to or a direction away from the physician. Similarly, “proximal” or “proximally” refer to a position near to or a direction towards the physician. 
     In describing examples, terminology is resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method can be performed in a different order than those described herein without departing from the scope of the disclosed technology. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified. 
     As discussed herein, a “patient” or “subject” can be a human or any animal. It should be appreciated that an animal can be a variety of any applicable type, including, but not limited to, mammal, veterinarian animal, livestock animal or pet-type animal, etc. As an example, the animal can be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). 
     As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g., “about 90%” may refer to the range of values from 71% to 99%. 
     By “comprising” or “containing” or “including” or “having” is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named. 
     It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges can be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, other exemplary embodiments include from the one particular value and/or to the other particular value. 
     The descriptions contained herein are examples of the disclosure and are not intended in any way to limit the scope of the disclosure. While particular examples of the present disclosure are described, various modifications to devices and methods can be made without departing from the scope and spirit of the disclosure. For example, while the examples described herein refer to particular components, the disclosure includes other examples utilizing various combinations of components to achieve a described functionality, utilizing alternative materials to achieve a described functionality, combining components from the various examples, combining components from the various example with known components, etc. The disclosure contemplates substitutions of component parts illustrated herein with other well-known and commercially-available products. To those having ordinary skill in the art to which this disclosure relates, these modifications are often apparent and are intended to be within the scope of the claims which follow.