Patent Description:
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 <NUM> or type <NUM> aortic arches with type <NUM> 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 <NUM>° bend, a <NUM>° bend and a <NUM>° bend in quick succession over a few centimetres 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.

The disclosure of <CIT> provides a clot retrieval device for removing occlusive clot from a blood vessel comprising an inner elongate body and an outer elongate body at least partially overlying the inner elongate body.

The disclosure of <CIT> provides a clot retrieval device for removing occlusive clot from a blood vessel, the device comprising an inner elongate body having a collapsed delivery configuration and an expanded deployed configuration and an outer elongate body at least partially overlying the inner elongate body.

It is an object of the present invention to provide devices 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.

The invention provides a clot retrieval device according to claim <NUM>. Further embodiments of the invention are provided in the dependent claims.

In some examples, struts of the distal scaffolding zone are connected to the inner expandable body.

In some examples, struts of the distal scaffolding zone form a mesh-like structure.

In some examples, the distal scaffolding zone can include a porosity greater than a porosity provided by the plurality of struts of the outer expandable body proximal thereof.

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.

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.

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 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 embodiments of the present disclosure have been illustrated and described, various modifications can be made without departing from the scope of the disclosure. For example, while the embodiments described herein refer to particular features, the disclosure includes embodiments having different combinations of features. The disclosure also includes embodiments that do not include all of the specific features described. Specific embodiments 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 cath lab procedures. It is assumed in the descriptions below that these products and methods are employed in conjunction with the device 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 dual layer construction in which the device includes an outer expandable member within which runs an inner expandable member, both members being directly or indirectly connected to an elongate shaft, and a distal net or scaffold configured at the distal end of the device to prevent the escape of clot fragments. This distal net may be appended to either the shaft, the inner or the outer members or to several of these. A range of designs are envisaged for each of these elements as described throughout this document, and it is intended that any of these elements could be used in conjunction with any other element, although to avoid repetition they are not shown in every possible combination.

For example both the inner and outer expandable members are desirably made from a material capable of recovering its shape automatically once released from a highly strained delivery configuration. A superelastic material such as Nitinol or an alloy of similar properties is particularly suitable. The material 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 a 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 inner expandable member may in some cases form a generally tubular structure and is ideally configured to expand to a lesser diameter than that of the smallest vessel in which it is intended to be used. This diameter is typically less than <NUM>% that of the outer expandable member may be as low as <NUM>% or less of the outer member diameter. A range of different distal scaffolding zone designs are disclosed, some of which incorporate strut elements from the framework of the outer and/or inner expandable members, and some of which incorporate fine wires or fibers to provide added scaffolding with minimal impact of overall device profile or deliverability. Suitable materials ideally have a high tensile strength so that a very fine wire or fiber with sufficient integrity for manufacturability and use can be produced, such as for example polymers materials such as UHMWPE, Aramid, LCP, PET or PEN, or metals such as Tungsten, MP35N, stainless steel or Nitinol.

<FIG> shows one embodiment of a clot retrieval device <NUM> with an outer expandable member <NUM> and an inner expandable member <NUM> to facilitate restoration of blood flow through clot immediately after device <NUM> is deployed at an obstructive site. As shown, member <NUM> can include four (<NUM>) expandable members proximal of the distal portion. However, any number of expandable members are contemplated. For example, <FIG> shows a modified device <NUM>' with fewer expandable member sections (e.g., two (<NUM>) as shown) of member <NUM>. <FIG> shows a side of device <NUM> but without the proximal shaft. Device <NUM> has an elongate shaft <NUM> having a distal end that extends interior of the artery and a proximal end that extends exterior of the artery. Members <NUM> and <NUM> have a collapsed configuration for delivery and an expanded configuration for clot retrieval, flow restoration and fragmentation protection. Member <NUM> can have a generally tubular body section.

Member <NUM> is configured to self-expand upon release from a restraining sheath (e.g., a microcatheter) to a diameter larger than that of member <NUM>. Expansion of member <NUM> can cause compression and/or displacement of the clot during expansion. When an expandable body provides a high level of scaffolding, the clot is compressed. When an expandable body provides an escape path or opening the expanding body will urge the clot towards the opening. However if the expandable body provides only modest scaffolding the clot will be displaced but since the clot has many degrees of freedom it may move in a variety of different directions and therefore cannot be controlled. By providing a tubular expandable body where the length of the tubular expandable body is substantially as long as the length of the occlusive clot or longer, many of the degrees of movement freedom available to the clot are removed.

Members <NUM> and <NUM> can specifically have a collapsed configuration for delivery and an expanded configuration for flow restoration and fragmentation protection. Members <NUM>, <NUM> can be joined at the proximal and distal ends during assembly to minimize tension within members <NUM>, <NUM> during use. In other examples, member <NUM> may not be connected to the distal end of member <NUM> at all or may be constrained within member <NUM> without being fixedly attached. In other examples, member <NUM> can have a non-cylindrical cross-section, may be non-uniform in diameter, and may have tailored strut patterns to provide regions of differing radial force or flexibility. The length of member <NUM> can be substantially the same as the length of member <NUM> in the freely expanded configuration and the loaded, collapsed configuration.

Member <NUM> can have an elastic or super-elastic or shape-memory metallic structure and can have a polished surface such as an electro-polished surface. Member <NUM> can be configured so as to provide a flow lumen or flow channel (e.g., generally cylindrical section) through device <NUM> to facilitate restoration of blood flow past the clot upon deployment. In one embodiment, member <NUM> is configured to scaffold the flow channel through the clot to prevent the liberation of fragments which might otherwise lodge in the distal vasculature. Member <NUM> can include one or more connected struts <NUM> configured to contact a clot when initially deployed in a target vessel within the clot. The contact of the one or more struts <NUM> with the clot provides additional grip and assists in the initial dislodgement of the clot from the vessel when device <NUM> is retracted.

The distal end of member <NUM> can include an expansile section formed from expanded struts <NUM> which have a diameter greater than that of member <NUM>. These expanded struts <NUM> can be connected to a coil section <NUM> (see, e.g., <FIG>) that can be laser cut from the tubing that member <NUM> can also be cut from. Coil <NUM> can also be configured to accommodate minor length differentials by stretching without applying significant tensile or compressive forces to device <NUM>. Coil <NUM> can be formed from a stainless-steel material, a polymer or from a more radiopaque metal such as gold or platinum or an alloy of such a material. Coil <NUM> can be replaced with a longitudinal length of an elastic material such as a low modulus polymer or elastomer. The distal end of the coil <NUM> can be joined to the distal collar <NUM> of member <NUM> (e.g., by adhesive, a solder, weld or braze process). In some examples, struts <NUM> can elongate during loading so that the lengths of the members <NUM>, <NUM> can be equal when fully loaded in a microcatheter. Length differentials between members <NUM>, <NUM> can still occur when device <NUM> is deployed in a small vessel or during the loading or deployment process.

Members <NUM> and <NUM> are preferably made of a super-elastic or pseudo-elastic material such as Nitinol or another such alloy with a high recoverable strain. Shaft <NUM> may be a tapered wire shaft, and may be made of stainless steel, MP35N, Nitinol or other material of a suitably high modulus and tensile strength. Shaft <NUM> may have indicator bands <NUM> to indicate when the distal end of device <NUM> is approaching the end of the microcatheter during insertion. Shaft <NUM> can have a coil <NUM> adjacent its distal end and proximal of members <NUM>, <NUM>. Coil <NUM> may be metallic and may be formed from stainless steel or from a more radiopaque material such as platinum or gold for example or an alloy of such a material. In other examples, coil <NUM> can be coated with a low friction material or have a polymeric jacket positioned on the outer surface of the coil <NUM>. Adjacent to coil <NUM> a sleeve <NUM> may be positioned on shaft <NUM>. Sleeve <NUM> may be polymeric and may be positioned over a tapered section of shaft <NUM>. Sleeve <NUM> may be rendered radiopaque through the addition of a filler material such as tungsten or barium sulphate. However, other radiopaque materials are contemplated, including but not limited to Bismuth SubCarbonate, Barium OxyChloride, Gold, Platinum, Iridium, Tantalum or an alloy of any of these materials. The sleeve <NUM> and shaft <NUM> may be coated with a material to reduce friction and thrombogenicity. The coating may include a polymer, a low friction lubricant such as silicon, a hydrophilic or a hydrophobic coating. This coating may also be applied to the member <NUM> and member <NUM>.

<FIG> shows a side plan view of member <NUM> while <FIG> shows a top plan view of member <NUM>. Inlet openings <NUM> are provided in member <NUM> whereby inlets <NUM> can provide a primary movement freedom available to the clot and so the expansion of member <NUM> urges the clot into reception space <NUM>. Member <NUM> can have multiple inlet mouths <NUM> to accept clot. Inlet mouths <NUM> can be configured to allow portions of the clot to enter reception space <NUM> and thus allow the clot to be retrieved without being excessively compressed. This is advantageous because the inventors have discovered that compression of clot causes it to dehydrate, which in turn increases the frictional properties of the clot, and increases its stiffness, all of which makes the clot more difficult to disengage and remove from the vessel. This compression can be avoided if the clot migrates inward through the wall of member <NUM> as the porous structure migrates outward towards the vessel wall.

The inlet mouths <NUM> can also provide the added benefit of allowing member <NUM> when retracted to apply a force to the clot in a direction substantially parallel to the direction in which the clot is to be pulled from the vessel (i.e. substantially parallel to the central axis of the vessel). This means that the outward radial force applied to the vasculature may be kept to a minimum, which in turn means that the action of the clot retrieval device <NUM> on the clot does not serve to increase the force required to dislodge the clot from the vessel, thus protecting delicate cerebral vessels from harmful radial and tensile forces.

Member <NUM>, as shown, can include proximal struts <NUM> connected at their proximal ends to collar <NUM> and at their distal ends to a first expandable member <NUM>, which is more clearly shown in <FIG> at section B-B. As shown, struts <NUM> may have a tapered profile to ensure a gradual stiffness transition from shaft <NUM> to the clot engagement section of the device. Member <NUM> can be connected to a second expandable member <NUM> by a plurality of connecting arms <NUM>, which can run from a proximal junction <NUM> to a distal junction <NUM>. Arms <NUM> can include generally straight struts running parallel to the central axis of the device. In other embodiments these connecting arms may include a plurality of struts configured in one or more cells or may include curved or spiral arms. The region between the first and second expandable member includes two inlet mouths <NUM> through which clot may pass and enter the reception space <NUM> defined by the region between the inner and outer members.

Member <NUM> can in turn be connected to a third expandable member <NUM> by connecting arms <NUM>, which run from a proximal junction <NUM> to a distal junction <NUM>. Arms <NUM> can include generally straight struts running parallel to the central axis of device <NUM>. In some examples, arms <NUM> can include a plurality of struts configured in one or more cells or may include curved or spiral arms. The region between members <NUM>, <NUM> can include one or more inlet mouths <NUM> through which clot may pass and enter the reception space <NUM> defined by the region between members <NUM>, <NUM>. Arms <NUM> between members <NUM>, <NUM> may be substantially aligned with arms <NUM> between members <NUM>, <NUM> to align the neutral axis of members <NUM>, <NUM>, <NUM> during bending. In other examples, arms <NUM> between members <NUM>, <NUM> may be aligned at an angle, such as <NUM> degrees, with arms <NUM> between members <NUM>, <NUM>.

In some examples, member <NUM> can include interconnected struts, such as with strut <NUM> terminating in crowns <NUM> with no distal connecting elements, and other struts such as <NUM> terminating in junction points <NUM> and <NUM>. Struts in the expandable members may be configured so that during loading, multiple crowns (e.g., crowns <NUM>, <NUM>) do not align at the same distance from the proximal collar <NUM>. During loading or resheathing, a higher force can be generally required to load a crown than a strut into the sheath. Accordingly, if multiple crowns are loaded at the same time the user may notice an increase in loading force. By offsetting the crowns (e.g., crowns <NUM>, <NUM>) by making alternative struts <NUM> and <NUM> different lengths the loading force may be reduced and the perception to the user is improved. Similarly, second expandable member <NUM> can include interconnected struts, such as strut <NUM>, terminating in crowns <NUM> with no distal connecting elements, and other struts (e.g., strut <NUM>) terminating in junction points. Similarly, third expandable member <NUM> can include interconnected struts, such as strut <NUM>, terminating in crowns <NUM> with no distal connecting elements, and other struts terminating in junction points. <FIG> shows a close-view of section C-C of <FIG> more clearly showing member <NUM> and its struts (e.g., strut <NUM>) and crowns <NUM>. As shown, fewer or great expandable members <NUM>, <NUM>, <NUM> may be included with member <NUM>.

In some examples, expandable members of member <NUM> may include one or more markers <NUM> with radiopaque materials such as, but not limited to, a radiodense material such as Gold, Tungsten, Tantalum, Platinum or alloy containing these or other high atomic number elements. Polymer materials (e.g., polyurethane, pebax, nylon, polyethylene, or the like) might also be employed, containing a Radiopaque filler such as Barium Sulphate, Bismuth SubCarbonate, Barium OxyChloride, Gold, Tungsten, Platinum, Iridium, Tantalum, an alloy of these materials, and/or an adhesive filled with radiopaque filler. In this respect, marker <NUM> can be included as an eyelet on struts throughout member <NUM>. Marker <NUM> can be positioned to indicate to the user the distal end of the barrel section of member <NUM> to aid in accuracy of deployment. The distal end of member <NUM> can include a circumferential ring of struts <NUM> connected to a series of struts <NUM> that can terminate at a distal junction point <NUM>, which can include a collar. In some examples, member <NUM> can terminate in a closed distal end while in other aspects, the distal end of member <NUM> can be opened or not necessarily closed. In some examples, struts <NUM> may include a generally conical shape, as shown. In some examples, struts <NUM> can be arranged in a generally flat plane which may be inclined or may be normal to the longitudinal axis of device <NUM>. Struts <NUM> and <NUM> can be tapered to a narrower width than those of the more proximal struts including the body of the expandable members (e.g., members <NUM>, <NUM>, <NUM>, etc) thus creating a gradual transition in the stiffness of the device both in the expanded and collapsed states.

<FIG> is a close-up view of section A-A of <FIG> more clearly showing example markers <NUM> staggered on and along member <NUM>. It is understood that the position of markers <NUM> as shown in <FIG> and throughout this disclosure are merely exemplary and markers <NUM> can be included elsewhere and with other features of device <NUM>. In some examples, markers <NUM> can be separated approximately <NUM> apart in the collapsed, delivery configuration and be separated approximately <NUM> apart in the expanded configuration. However, markers <NUM> are not so limited and can separated as needed or required.

<FIG> shows a close-up view of section D-D of <FIG> more clearly showing distal region <NUM> while <FIG> shows close-up isometric view of a distal region <NUM> (sometimes referred herein interchangeably as a distal scaffolding zone) of device <NUM> at section E-E of <FIG>. <FIG> (end view) and 10B (isometric view) show the distal region <NUM> of member <NUM> only where a three-dimensional distal mesh of region <NUM> is configured for fragment protection feature is created by a framework of struts. As shown, a plurality of apexes or crowns <NUM> of distal region <NUM> shown in <FIG> are provided connected to a plurality of arms <NUM> proximal thereof, which terminate at a junction proximate collar <NUM>. Arms <NUM> can be shaped as needed or required, including generally bowed or conical as depicted. Preferably, arms <NUM> form a plurality of closed cells gradually going from larger closed cells at or adjacent the proximal end of region <NUM> to smaller closed cells at or adjacent the distal end. In some examples, at least twelve closed cells can be provided in distal region <NUM> of device <NUM>. The distal region <NUM> shown can include a closed distal end of member <NUM> which, together with the mesh formed by arms <NUM> of region <NUM> and corresponding closed cells, can prevent egress of clot or clot fragments that have entered the previously described reception space <NUM> between members <NUM>,<NUM>.

In some examples, axially aligned smaller diamond shaped cells <NUM> can be formed by arms <NUM> and positioned along upper and lower regions of the distal mesh. In some examples, at least two cells <NUM> are provided. Larger cells <NUM> can be positioned radially about longitudinal axis L of device <NUM> and radially inward of cells <NUM>. In some examples, at least four cells <NUM> are provided joined at or adjacent a junction proximate collar <NUM>. In some examples, cells <NUM> can measure approximately <NUM>, said measurement being the size of a best fit diameter of a circle placed in respective cell (e.g., cell <NUM> of shown drawn in the top view of <FIG>). In other examples, cells <NUM> can measure larger (e.g., approximately <NUM>).

Cells <NUM> can also be provided proximal of cells <NUM>, <NUM>. In some examples, at least five (<NUM>) cells <NUM> radially separated about axis L can be positioned proximal of cells <NUM>, <NUM>. Each of cells <NUM> can include struts common with cells <NUM>, <NUM> as well as crowns <NUM>. In some examples, the proximal struts of each of cells <NUM> can be bowed or otherwise curved. In some examples, the distal region <NUM> of <FIG> shown can be a monolithic structure integrally formed with regions of member <NUM> proximal thereof (e.g., by being laser machined from the same tube as the rest of member <NUM>). In some examples, radiopaque coil <NUM> (e.g., formed of platinum, gold, an alloy, etc.) can be positioned distal of the distal region <NUM> configured to couple at or against distal collar <NUM>.

<FIG> shows a close-up isometric view of an example marker <NUM> while <FIG> shows a side plan view of marker <NUM>. The markers <NUM> shown are formed generally of platinum-iridium, though as previously discussed, other radiopaque materials are contemplated as needed or required.

<FIG> shows a close-up of expandable member <NUM> in a collapsed configuration showing example laser cut patterns with enhanced visibility. It is understood that other expandable members of member <NUM> may follow the same or similar pattern. Member <NUM> may include three (<NUM>) eyelet cuts staggered for marker <NUM>. In other examples, member <NUM> may include four (<NUM>) eyelet cuts staggered for marker <NUM>. Fewer or greater eyelet cuts can be included as needed or required to incorporate markers <NUM>. In those examples with <NUM> eyelet cuts, each expandable member of member <NUM> can include <NUM> markers <NUM>. In this respect, if member <NUM> were to have three expandable members, then member <NUM> could include a total of at least twelve markers <NUM> staggered throughout. If member <NUM> were to have four expandable members, then at least twenty markers <NUM> could be included with member <NUM> staggered throughout.

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).

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.

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.

Claim 1:
A clot retrieval device (<NUM>) to remove clot from a blood vessel, the device comprising a collapsed configuration and an expanded configuration and comprising:
an inner expandable body (<NUM>) comprising a framework of struts that form closed cells; and
an outer expandable body (<NUM>) comprising a framework of struts that form closed cells (<NUM>, <NUM>, <NUM>) larger than the closed cells of the inner expandable body and at least partially radially surrounding the inner expandable body, the outer expandable body comprising a distal scaffolding zone (<NUM>) comprising a plurality of struts that distally taper with closed cells smaller than cells proximal thereof in the outer expandable body;
the plurality of closed cells of the distal scaffolding zone comprising:
a first plurality of closed cells being axially aligned smaller diamond shaped cells (<NUM>) formed by struts of the distal scaffolding zone;
a second plurality of closed cells (<NUM>) being larger than cells of the first plurality of closed cells and radially separated, each smaller diamond shaped cell being radially inward and distal of each of the second plurality of closed cells; and
a third plurality of closed cells radially separated and proximal of each of the second plurality of closed cells; and
a fourth plurality of closed cells (<NUM>) radially inward and distal of the first plurality of closed cells.