Patent Description:
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 a number of access challenges that make it difficult to deliver treatment devices to a clot or other obstruction. 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 centimeters of vessel. In the case of pulmonary embolisms, access may be gained 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 an obstruction retrieval device be compatible with a delivery catheter having a low profile and high flexibility.

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 more superior vessels.

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.

The clots may not only range in shape and consistency, but also may vary greatly in length, even in any one given area of the anatomy. For example, clots occluding the middle cerebral artery of an ischemic stroke patient may range from just a few millimeters to several centimeters in length.

Stent-like clot retrievers are being increasingly used to remove clot and other obstructions from cerebral vessels of acute stroke patients. These are self-expanding devices, similar in appearance to a stent attached to the end of a long shaft and are advanced through a microcatheter and deployed across clot obstructions in order to trap and retrieve them. They rely on a pinning mechanism to grab the clot by trapping the clot between the self-expanding stent-like body and the vessel wall.

Typically, a stent-like clot retriever relies on its outward radial force (RF) to retain its grip on the clot. If the RF is too low the stent-like clot retriever will lose its grip on the clot, but if the RF is too high the stent-like clot retriever may damage the vessel wall and may require too much force to withdraw. Because clots vary in morphology across patients, RF required to grip the clot also varies. Because blood vessel fragility and geometry also varies across patients, RF required to reduce the risk of vessel trauma also varies.

In some treatments, some known stent-like clot retriever designs can lose their grip on a clot when withdrawn proximally around a bend in a tortuous vessel. This typically occurs because the struts of the stent-like clot retriever are placed in tension when it is retracted. This tension is due to friction between the device and the blood vessel and is increased if an additional load is applied load such as that provided by a clot. In a bend the struts on the outside of the bend are placed in higher tension than those on the inside. In order to attain the lowest possible energy state, the outside surface of the stent moves towards the inside surface of the bend, which reduces the tension in the struts, but also reduces the expanded diameter of the stent-like clot retriever.

Some treatments rely on pinning the clot between the stent-like clot retriever and the vessel wall and thus may not restrain the clot effectively when passing a branch vessel or when passing into a vessel that is larger than the fully expanded diameter of the stent-like clot retriever. Pinning the clot between the stent-like clot retriever and the vessel wall in order to remove it from the vessel also results in high shear forces against the side of the clot as it is removed, potentially releasing fragments of the clot. If these fragments are not retained by the device, they may be released leading to further blockages in the distal vasculature.

In some treatments, the stent-like clot retriever may be shorter than the clot itself. A device that is shorter than the clot is unlikely to be able to restore flow through the occluded area upon deployment, and thus the pressure gradient across the clot remains a significant impediment to its removal. Simply making such a device longer would likely render it difficult to track through tortuous anatomies and could be traumatic to the vasculature, taking more force to withdraw and potentially getting stuck and requiring surgery to remove.

For many reasons including some or all of the above limitations it is often necessary for a physician to make multiple passes with a clot retrieval device in order to fully remove an obstructive clot. However, each time a clot retrieval device is withdrawn the access to the target site is lost. The initial access steps of placing the large bore catheter do not need to be repeated as it remains in place after the initial clot retrieval attempt. Only the steps of accessing the clot site after the large bore catheter has been placed need to be repeated. Thus, it is necessary to re-advance a guidewire and microcatheter to access and re-cross the clot, and then remove the guidewire and advance the clot retrieval device through the microcatheter. Navigating the guidewire and microcatheter to the clot can take a considerable amount of time, especially if the vessels are tortuous. This additional time and device manipulation all adds to the risks to which the patient is exposed.

The disclosure of <CIT> provides a method for using a clot retrieval device for treating a clot in a blood vessel for use in the treatment of ischemic stroke to reperfuse an obstructed vessel.

The invention is defined by the scope of the appended claims. Examples disclosed herein generally include a clot retrieval device having an inner expandable member and an outer expandable member, each formed from respective strut frameworks such that the outer expandable member has larger cell openings than the inner expandable member. The outer expandable member can have multiple discontinuous body segments spaced apart in relation to a longitudinal axis of the device. Adjacent discontinuous body segments can be joined by a pair of tapered connecting arms that are able to bend with a small radius of curvature compared to the body segments. This small radius of curvature can have a range of values depending on the tortuosity of the vasculature the device is expanded in. It will approximately equal <NUM> when the device is in a straight vessel and will approximately equal <NUM> when the device is in a vessel with a <NUM>-degree bend. Some or all of the body segments can include radiopaque markers positioned to illustrate a circumference of the respective body segment and slightly staggered in relation to a longitudinal axis of the device such that the markers nest when the device is collapsed for delivery.

An example clot retrieval device has a collapsed configuration and an expanded configuration. The clot retrieval device is configured to remove clot from a blood vessel. The clot retrieval device has an inner expandable member and an outer expandable member. The inner expandable member has a first framework of struts and the outer expandable member has a second framework of struts. The second framework at least partially radially surrounds the inner expandable member.

Closed cells of the second framework of the outer expandable member can be larger than closed cells of the first framework of the inner expandable member.

The outer expandable member can have a first and a second body segment connected by two connecting arms, wherein the first body segment is positioned in a proximal direction in relation the second body segment. Each of the two connecting arms respectively can have a tapered shape that is wider where the arm is near the first, proximal body segment and narrower where the arm is near the second, distal body segment. As shown in <FIG> and <FIG>, approximate values for the labelled dimensions are as follows; the height 'H' has a value of <NUM>, the strut width 'W1' has a value of <NUM>, the strut width 'W2' has a value of <NUM> and the strut width 'W3' has a value of <NUM>. Hence, the approximate percentage change in width between 'W1' and 'W2' is a decrease of <NUM>% and the approximate percentage change in width between 'W2' and 'W3' is an increase of <NUM>%. The outer expandable member can have additional body segments connected to the first and/or second body segment by additional connecting arms.

The outer expandable member can have at least two inlet mouths in the second framework including a pair of inlet mouths between the first and second body segments. Each of the two inlet mouths between the first and second body segment can have a respective opening bounded by the first body segment, the second body segment, and the two connecting arms.

The first body segment can have at least two pairs of struts each terminating in a respective distal apex and forming a proximal boundary of a respective inlet mouth of the two inlet mouths.

The two connecting arms between the first and second body segments of the outer expandable member can extend substantially parallel to a longitudinal axis of the device.

The two connecting arms between the first and second body segments of the outer expandable member can be positioned approximately <NUM>° from each other about a circumference of the outer expandable member.

The first body segment and the second body segment can be connected to each other solely via the two connecting arms.

Each of the two connecting arms can be configured to bend with a curvature having a radius smaller than a radius of curvature of a majority of struts of the first body segment and the second body segment as the clot retrieval device is pulled proximally through a tubular vasculature comprising a bend of about <NUM>°.

The outer expandable member can have three or more body segments each shaped substantially similarly to the first body segment and the second body segment. The outer expandable member can include pairs of tapered connecting arms such that each respective pair of tapered connecting arms joins longitudinally adjacent body segments of the three or more body segments. The tapered connecting arms can be shaped and oriented similarly to the connecting arms between the first and second body segments.

One or both of the first and second body segments can respectively include four or more radiopaque markers positioned around a circumference of the respective body segment. When the clot retrieval device is in the collapsed configuration, each of the radiopaque markers can be offset from adjacent radiopaque markers of the four or more radiopaque markers. The markers can be offset from adjacent radiopaque makers in relation to a longitudinal axis of the device. When the clot retrieval device is in the collapsed configuration, alternating radiopaque markers of the four or more radiopaque markers can be aligned in a plane orthogonal to the longitudinal axis.

The first body segment can include a first set of four or more radiopaque markers. The second body segment can include a second set of four or more radiopaque markers. When the clot retrieval device is in the expanded configuration, the first and second sets of four or more radiopaque markers are spaced approximately <NUM> millimeters apart, measured in the direction of the longitudinal axis. When the clot retrieval device is in the collapsed configuration, the first and second sets of four or more radiopaque markers are spaced approximately <NUM> millimeters apart, measured in the direction of the longitudinal axis.

Each of the four or more radiopaque markers can include radiopaque material positioned in an eyelet.

At least two of the four or more radiopaque markers can be aligned, in the direction of the longitudinal axis, with a respective connecting arm of the two connecting arms.

Another example clot retrieval device can have a collapsed configuration and an expanded configuration. The clot retrieval device is configured to remove clot from a blood vessel. Structures and functionality of this example clot retrieval device are combinable with structures and features of the previous example clot retrieval device.

The example clot retrieval device includes an inner expandable member having a first framework of struts and an outer expandable member having a second framework of struts. The second framework of struts can form closed cells larger than closed cells of the first framework of inner expandable member. The second framework can at least partially radially surround the first framework of the inner expandable member.

The example clot retrieval device can include four or more radiopaque markers affixed to the second framework of struts and positioned to indicate a circumference of the outer expandable member. The radiopaque markers can be further positioned such that when the clot retrieval device is in the collapsed configuration, each of the radiopaque markers is offset, in relation to a longitudinal axis of the device to respective circumferentially adjacent radiopaque markers.

The outer expandable member can include discontinuous body segments spaced apart from each other in the direction of the longitudinal axis. The radiopaque markers can be positioned to indicate a circumference of a body segment of the discontinuous body segments.

The example clot retrieval device can include a first body segment and a second body segment, wherein the first body segment is positioned in a proximal direction in relation the second body segment. The outer expandable member can include two connecting arms joining the first body segment to the second body segment. Each of the two connecting arms can respectively have a tapered shape that is wider near the proximal, first body segment and narrower near the distal, second body segment.

The outer expandable member can include two inlet mouths in the second framework. Each of the two inlet mouths can include a respective opening bounded by the first body segment, the second body segment, and the two connecting arms.

The first body segment can include the four or more radiopaque markers forming a first set of markers, and the second body segment can include a second set of four or more radiopaque markers positioned to indicate a circumference of the second body segment. The second set of radiopaque markers can be positioned such that when the clot retrieval device is in the collapsed configuration, each of the radiopaque markers of the second set is offset, in relation to a longitudinal axis of the device to respective adjacent radiopaque markers of the second set. Markers in the first set of radiopaque markers can be similarly offset.

The two connecting arms can be positioned approximately <NUM>° from each other about a circumference of the outer expandable member.

Specific embodiments of the present invention 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 of this invention and do not need to be described in detail.

Although the description of the invention is in many cases in the context of treatment of intracranial arteries, the invention may also be used in other body passageways as previously described. The scope of the invention is defined only by the scope of the appended claims.

<FIG> shows a distal portion of an example clot retrieval device <NUM> in an expanded configuration. The clot retrieval device <NUM> generally extends to define a longitudinal axis A-A and has a distal coil <NUM> at its distal end, an outer expandable member <NUM> and an inner expandable member <NUM> extending proximally and coaxially from the distal coil <NUM>, and a proximal coil <NUM> extending proximally from the outer expandable member <NUM> and the inner expandable member <NUM>. The device <NUM> can include additional features such as an elongate shaft <NUM>, a sleeve <NUM>, and indicator bands <NUM>. The device <NUM> can include a distal junction or collar <NUM> joining the distal coil <NUM> to the outer expandable member <NUM> and the inner expandable member <NUM>. The device <NUM> can include a proximal junction or collar <NUM> joining the proximal coil <NUM> to the outer expandable member <NUM> and the inner expandable member <NUM>. The junctions <NUM>, <NUM> can be constructed as usable with a clot retrieval device having two expandable layers <NUM>, <NUM> such as described in <CIT>.

<FIG> shows a close-up of a portion of the clot retrieval device illustrated in <FIG>, the portion including a tapered strut according to aspects of the present invention.

<FIG> shows a plan view of a first side of the clot retrieval device <NUM>. <FIG> shows the view clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration. <FIG> shows a plan view of a second side of the clot retrieval device <NUM>, the second side viewed at <NUM>° from the first side view illustrated in <FIG>. <FIG> shows the view clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration. <FIG> shows a linear view of the outer expandable member <NUM> cut along a line B-B indicated in <FIG> and <FIG> and flattened. <FIG> shows a close-up of a portion of the outer expandable member <NUM> as indicated in <FIG>. <FIG> shows a close-up of a portion of the outer expandable member <NUM> as indicated in <FIG>. <FIG> shows a plan view of a distal end of the clot retrieval device <NUM>. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration.

As described in greater detail in relation to <FIG> and <FIG>, the outer expandable member <NUM> can include tapered struts <NUM>, <NUM> joining body segments <NUM>, <NUM>, <NUM>. The tapered struts <NUM>, <NUM> are shaped to provide flexibility to the outer expandable member <NUM> to facilitate withdraw of the device <NUM> from tortuous vascular when an obstruction is at least partially confined by the outer expandable member <NUM>. Additionally, or alternatively, the tapered struts <NUM>, <NUM> are shaped to promote apposition of the outer expandable member <NUM> circumferentially to blood vessel walls as the device <NUM> is withdrawn through tortuous vasculature when an obstruction is at least partially confined by the outer expandable member <NUM>.

As described in greater detail in relation to <FIG>, the outer expandable member <NUM> can include staggered radiopaque markers positioned to facilitate visualization of the device <NUM> during treatment while also maintaining a small profile collapsed configuration of the outer expandable member <NUM> to facilitate traverse of the collapsed device <NUM> across a clot or other obstruction.

Referring collectively to <FIG>, the outer expandable member <NUM> and inner expandable member <NUM> are collapsible into a restraining sheath (e.g. microcatheter) sized to traverse a clot or other obstruction. The outer expandable member <NUM> and inner expandable member <NUM> are each configured to self-expand upon release from the restraining sheath. In the expanded configuration, the device <NUM> can facilitate clot retrieval, flow restoration, and/or fragmentation protection.

Both the inner and outer expandable members <NUM>, <NUM> are preferably made from a material capable of recovering its shape automatically once released from a constricted delivery configuration. A super-elastic or pseudo-elastic material such as Nitinol or an alloy of similar properties is particularly suitable. The material can have a high recoverable strain sufficient to resiliently collapse and expand as described herein. 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 understood by a person skilled in the pertinent art according to the teachings disclosed herein. The framework may be rendered visible under fluoroscopy through the addition of alloying elements or through a variety of other coatings or marker bands. For instance, the framework can include material and/or markers with radiopaque material including, but not limited to Barium Sulphate, Bismuth SubCarbonate, Barium OxyChloride, Gold, Tungsten, Platinum, Iridium, Tantalum, and alloys thereof. Specifically, in some examples, the framework can include radiopaque markers having an Iridium alloy, and more specifically a Platinum-Iridium alloy.

The inner expandable member <NUM> is preferably configured to expand to a lesser diameter D2 than that of the smallest vessel in which it is intended to be used. This diameter D2 is typically less than <NUM>% that of the diameter D1 of the outer expandable member <NUM> and may be as low as <NUM>% or less of the outer member diameter D1.

A distal scaffolding zone can incorporate strut elements from the framework of the outer and/or inner expandable members <NUM>, <NUM> such as an expanded portion <NUM> of the inner expandable member <NUM> and a distal portion <NUM> of the outer expandable member <NUM>. The strut geometry of the distal scaffolding zone can be shaped as illustrated herein, or as described in relation to compatible stent-like clot retrievers, including but not limited to as disclosed in <CIT>. The distal scaffolding zone can further include 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 like UHMWPE, Aramid, LCP, PET or PEN, or metals such as Tungsten, MP35N, stainless steel or Nitinol.

In each of the expanded configuration and the collapsed configuration, the inner expandable member <NUM> and outer expandable members define respective tubular bodies. Preferably the tubular bodies are coaxial about the longitudinal axis A-A. The device <NUM> includes a reception space <NUM> within the outer expandable member <NUM> and outside the inner expandable member <NUM> when the inner and out expandable members <NUM>, <NUM> are in the expanded configuration. The device <NUM> and reception space <NUM> are sized, shaped, and otherwise configured to allow a clot to become at least partially confined within the reception space during a clot removal treatment. The interior of the inner expandable member <NUM> when expanded is configured to provide a flow path through which blood can flow when the device <NUM> is expanded through a clot.

During a clot removal treatment, the length of the outer expandable member <NUM> can be about as long as the length of the occlusive clot or longer to remove many of the degrees of freedom of movement freedom otherwise available to the clot. The outer member <NUM> includes inlet openings <NUM> sized, shaped, another otherwise configured to provide the primary freedom of movement available to the clot and so the expansion of the outer member <NUM> urges the clot into the reception space <NUM>. The outer member <NUM> has multiple inlet mouths <NUM> to accept the clot. In this way inlet mouths <NUM> allow portions of the clot to enter reception space <NUM> of the outer member <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 scaffolding of the outer member <NUM> as the scaffolding migrates outward towards the vessel wall.

The inlet mouths <NUM> can further allow the outer 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.

The outer expandable member <NUM> includes proximal struts <NUM> connected at their proximal ends to the proximal collar <NUM> and at their distal ends to a proximal body segment <NUM>. The proximal struts <NUM> can have a tapered profile or be otherwise configured to provide a gradual stiffness transition from the shaft <NUM> to the tubular body of the outer expandable member <NUM>.

The proximal body segment <NUM> is connected to a middle body segment <NUM> by two connecting arms <NUM>, which run from a proximal junction <NUM> to a distal junction <NUM>. The middle body segment <NUM> is in turn connected to a distal body segment <NUM> by two connecting arms <NUM>, which run from a proximal junction <NUM> to a distal junction <NUM>. The region between the middle and distal body segments <NUM>, <NUM> 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 <NUM>, <NUM>.

As illustrated in greater detail in <FIG> and <FIG>, each of the connecting arms <NUM> can have a tapered profile with a width that tapers from a wider dimension W1 at the respective proximal junction <NUM>, <NUM> to a narrower width W2 near the respective distal junction <NUM>, <NUM>. At the distal junction <NUM>, <NUM>, the connecting arms <NUM>, <NUM> can expand to a width W3 that is wider than the narrower width W2 to accommodate branching distal struts <NUM>. The connecting arms <NUM>, <NUM> can have a height H (thickness) that is substantially uniform. The height H can be consistent with the strut thickness of the majority of the outer expandable member <NUM>.

In one example, as shown in <FIG> and <FIG>, approximate values for the labelled dimensions are as follows; the height H has a value of about <NUM>, the proximal strut width W1 has a value of about <NUM>, the distal strut width W2 has a value of about <NUM> and the bifurcation strut width W3 has a value of about <NUM>. Hence, the approximate percentage change in width between the proximal width W1 and the distal width W2 is a decrease of <NUM>% and the approximate percentage change in width between the distal width W2 and the bifurcation width W3 is an increase of <NUM>%.

The tapered shape of the connecting arms <NUM>, <NUM> can be configured to bend to reduce withdrawal force around blood vessel bends compared to a similarly constructed stent-like clot retriever device having non-tapered connecting arms. The arms <NUM>, <NUM> can be configured to bend with a curvature having a larger curvature (smaller radius of curvature) compared to a majority of struts within the outer expandable member <NUM>. (See radius r as illustrated in <FIG>.

The connecting arms <NUM> between the proximal body segment <NUM> and the middle body segment <NUM> of the outer expandable member <NUM> can be substantially aligned with the connecting arms <NUM> between the middle and distal body segments <NUM>, <NUM> to align the neutral axis of the body segments <NUM>, <NUM>, <NUM> during bending. In another embodiment the connecting arms <NUM> between the proximal body segment <NUM> and the middle body segment <NUM> can be aligned at an angle, such as <NUM>° to the connecting arms <NUM> between the middle and distal body segments <NUM>, <NUM>.

As illustrated in greater detail in <FIG> and <FIG>, the proximal body segment <NUM> includes interconnected struts, with certain struts such as strut <NUM> terminating in a distal apex <NUM> with no distal connecting elements, and other struts such as <NUM> terminating in junction points <NUM>, <NUM>. The middle body segment <NUM> includes interconnected struts, with certain struts such as strut <NUM> terminating in a distal apex <NUM> with no distal connecting elements, and other struts such as strut <NUM> terminating in junction points <NUM>.

One or more of the body segments <NUM>, <NUM>, <NUM> can include marker bands or radiopaque features such as gold or platinum marker or coils. In the illustrated embodiment, oval markers <NUM>, <NUM> are shown fixed in eyelets on struts on the proximal, middle, and distal body segments <NUM>, <NUM>, <NUM>. The markers <NUM> on the distal body segment <NUM> can be positioned to indicate to the user the position of the distal body segment <NUM> and therefore distal portion of the device <NUM> to aid in accuracy of deployment of the device <NUM>. The distal body segment <NUM> can include a single marker <NUM> to indicate the position of the distal body segment <NUM>, or multiple markers to indicate a circumference of the distal body segment <NUM>. Each of the proximal and middle body segments <NUM>, <NUM> can include multiple oval markers <NUM> positioned circumferentially around the respective body segment <NUM>, <NUM> to indicate to the user the expanded circumference C1 and/or position of the respective body segments <NUM>, <NUM> during a treatment (where the circumference C1 is the diameter D1 times pi). In the illustrated embodiment, each of the proximal and middle body segments <NUM>, <NUM> includes four markers <NUM> positioned approximately equidistant around a circumference C1 of the outer expandable member <NUM>.

<FIG> illustrate the outer expandable member <NUM> cut along the line B-B as indicated in <FIG> and <FIG>, laid flat, and collapsed so to a height C2 corresponding to a circumference of the outer expandable member <NUM> when the device <NUM> is constrained by a microcatheter or sheath. As illustrated in greater detail in <FIG>, the markers <NUM> on each of the proximal body segment <NUM> and the middle body segment <NUM> are staggered, offset in the direction of the longitudinal axis A-A (i.e. positioned at different distances from the proximal collar <NUM>) to facilitate collapse of the height C (circumference) of the outer expandable member <NUM>. Each of the respective markers <NUM> connect to an elongated segment <NUM> which is shaped to nest the adjacent markers <NUM> between a junction (e.g. junction <NUM>) and the respective connected marker <NUM>. The elongated segments <NUM> and markers <NUM> are positioned in an alternating fashion circumferentially.

The struts in the body segments <NUM>, <NUM>, <NUM> can be configured so that during loading, crowns or junctions (e.g. junction <NUM> and junction <NUM> and other similarly shaped junctions) do not align at the same distance from the proximal collar. During loading or re-sheathing, a higher force is generally required to load a junction (crown) than a strut into the sheath, therefore if multiple crowns are loaded at the same time the user may notice an increase in loading force. By offsetting the crowns by making alternative struts <NUM> and <NUM> different lengths the loading force may be reduced and the perception to the user is improved.

The distal end of the distal body segment <NUM> includes struts forming a tapered shape terminating at the distal junction point <NUM>, thus defining a closed end distal to the outer member <NUM>. The distal body segment <NUM> is viewed from the distal end of the device <NUM> in a planar view in <FIG> with the inner expandable member <NUM> removed in <FIG> for the purposes of illustration and the outer expandable member <NUM> removed in <FIG> for the purposes of illustration. The distal end of the distal body segment <NUM> can include a distal framework as illustrated herein, or an alternative distal framework usable with a stent-like clot retriever device. The tapered portion of the distal body segment <NUM> can be shaped and otherwise configured to prevent egress of clot or clot fragments that have entered the reception space <NUM> between the inner and outer members <NUM>, <NUM>. The expanded distal struts <NUM> of the inner member <NUM> act as an additional three dimensional filter in combination with the closed end of the outer member <NUM> to further prevent the egress of clot or clot fragments. In certain embodiments this distal section may comprise fiber attachment points such as eyelets or other fiber attachment features and fibers may be connected to the distal section at these attachment points to create a distal net.

As illustrated in greater detail in <FIG>, <FIG>, and <FIG>, the inner expandable member <NUM> is configured to self-expand upon release from a restraining sheath (such as a microcatheter) to a diameter D2 that is larger than the expanded diameter D1 of the outer expandable member <NUM> and smaller than a diameter of a blood vessel that the device <NUM> is configured to treat. The inner tubular member <NUM> includes a scaffolding that is denser, having smaller openings, compared to the outer expandable member <NUM>. The inner tubular member <NUM> is configured so as to provide a flow lumen through the device <NUM> to facilitate the immediate restoration of blood flow past the clot upon deployment. Additionally, or alternatively, the inner tubular member <NUM> is configured to scaffold said flow lumen through the clot to prevent the liberation of fragments which might otherwise lodge in the distal vasculature. The inner tubular member <NUM> includes connected struts <NUM> that may contact a clot when initially deployed in a target vessel within the clot. The contact of the struts <NUM> of the inner tubular member <NUM> with the clot can provide additional grip and assists in the initial dislodgement of the clot from the vessel when the device is retracted.

Inner expandable member <NUM> includes a generally cylindrical section of interconnected struts <NUM>, which is connected at its proximal end by a strut <NUM> (or multiple struts) to the proximal junction <NUM>. The distal end of the inner expandable member <NUM> includes of an expansile section formed from expanded struts <NUM> which have a diameter greater than the diameter D2 of the body section of the inner tubular member <NUM>. These expanded struts <NUM> are connected to a coil section <NUM> which in this embodiment is laser cut from the tubing that the inner expandable member <NUM> is also cut from during processing.

The shaft <NUM> can include 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> on the shaft to indicate to the user when the distal end of the device is approaching the end of the microcatheter during insertion. These bands are positioned so that as they approach a microcatheter hub or hemostasis valve they indicate the distal tip of the device is approaching the end of the microcatheter. These indicator bands can be formed by printing or removing or masking areas of shaft coating so that they are visually differentiated from the remainder of the shaft. The indicator bands <NUM> can additionally be recessed below the surface of the shaft <NUM> to give tactile feedback to the user as they approach the microcatheter.

The proximal coil <NUM> can extend from a distal portion of the shaft <NUM>. The proximal coil <NUM> coil can 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. Additionally, or alternatively, the coil may be coated with a low friction material or have a polymeric jacket positioned on the outer surface of the coil. Adjacent to this coil <NUM> a sleeve <NUM> may be positioned on shaft <NUM>. This sleeve <NUM> can include polymeric material and may be positioned over the tapered section of the shaft. The sleeve <NUM> may be rendered radiopaque through the addition of a filler material such as tungsten or barium sulphate. The sleeve <NUM> and shaft <NUM> may be coated with a material to reduce friction and thrombogenicity. The coating may consist of a polymer, a low friction lubricant such as silicon, a hydrophilic or a hydrophobic coating. This coating may also be applied to the outer member <NUM> and inner tubular member <NUM>.

The outer member <NUM> and the inner tubular member <NUM> can joined at the proximal junction <NUM> and the distal junction <NUM> during assembly. To minimize tension within the members <NUM>, <NUM> during use, the length of the outer member <NUM> can be substantially the same as the length of the inner member <NUM> in the freely expanded configuration and the collapsed, loaded configuration. The expanded struts <NUM> of the inner tubular member <NUM> elongate during loading so that the lengths of the inner and outer members are equal when fully loaded in a microcatheter. Length differentials between the inner member <NUM> and the outer member <NUM> can still occur when the device is deployed in a small vessel or during the loading or deployment process. The coil <NUM> at the distal end of the inner tubular member <NUM> can accommodate minor length differentials by stretching without applying significant tensile or compressive forces to the device. In another embodiment this coil <NUM> could be formed separately to the inner tubular member <NUM> and then be assembled to it. The 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. The coil <NUM> can also be replaced with a longitudinal length of an elastic material such as a low modulus polymer or elastomer.

In other embodiments the inner member <NUM> may not be connected to the distal end of the outer member <NUM> at all or may be constrained within the outer member <NUM> without being fixedly attached. In other embodiments the inner member <NUM> may 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.

<FIG> shows an isometric view of another example clot retrieval device <NUM>. Compared to the device <NUM> illustrated in Figures 1A through 5D, the outer expandable member <NUM> of the clot retrieval device <NUM> illustrated in <FIG> includes multiple middle body segments <NUM> rather than a single middle body segment <NUM>. At least the proximal <NUM> and the middle body segments <NUM> respectively include interconnected struts, with certain struts terminating in a distal apex <NUM> with no distal connecting elements, and other struts terminating in junction points. The device <NUM> illustrated in <FIG> includes three middle body segments <NUM>. According to the present invention, a clot retrieval device including features described and illustrated herein can include one, two, three, four, five, or more middle body segments. The device <NUM> includes an inner expandable member <NUM> elongated to accommodate the additional middle body segments <NUM> of the outer expandable member <NUM>.

The device <NUM> can include a reception space <NUM> between the outer expandable member <NUM> and inner expandable member <NUM> configured similarly to the reception space <NUM> of the device <NUM> illustrated in <FIG>.

The device <NUM> can further include a proximal coil <NUM>, distal coil <NUM>, distal junction <NUM>, and proximal junction <NUM> structured similarly as corresponding components <NUM>, <NUM>, <NUM>, <NUM> illustrated in Figures 1A through 5D. The device <NUM> can further include a sleeve, shaft, and indicator bands structured similar as corresponding components <NUM>, <NUM>, <NUM> illustrated in <FIG>.

<FIG> shows a close-up of a portion of the clot retrieval device <NUM> illustrated in <FIG>. The portion includes a tapered connecting arm <NUM>. The connecting arm <NUM> can be shaped as illustrated and described in relation to tapered connecting arms <NUM>, <NUM> of the device <NUM> illustrated in <FIG>. Connecting arms <NUM> can join the proximal, middle, and distal body segments <NUM>, <NUM>, <NUM> and be otherwise configured in a similar manner as connecting arms <NUM>, <NUM> of the device <NUM> illustrated in <FIG>.

<FIG> shows a plan view of a first side of the clot retrieval device <NUM>. <FIG> shows the view clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration.

The outer expandable member <NUM> of the device <NUM> can include a proximal struts <NUM> and a proximal body segment <NUM> structured similarly to the proximal struts <NUM> and proximal body segment <NUM> of the device <NUM> illustrated in <FIG>. The outer expandable member <NUM> can include a distal body segment <NUM> structured similarly to the distal body segment <NUM> of the device <NUM> illustrated in <FIG>. The outer expandable member <NUM> can include radiopaque markers <NUM>, <NUM>, <NUM> positioned and otherwise configured similarly to corresponding markers <NUM>, <NUM>, <NUM> of the device <NUM> illustrated in <FIG>. The outer expandable member <NUM> can include inlet mouths <NUM> configured similarly to inlet mouths <NUM> of the device <NUM> illustrated in <FIG>.

The inner expandable member <NUM> can include distal crown struts <NUM>, interconnecting struts <NUM> in a tubular body portion, and proximal connecting struts <NUM> similar to corresponding struts <NUM>, <NUM>, <NUM> of the device <NUM> illustrated in <FIG>. The inner expandable member <NUM> can be connected to an inner coil <NUM> configured similar to the inner coil <NUM> of the device <NUM> illustrated in <FIG>.

<FIG> shows a plan view of a second side of the clot retrieval device illustrated in <FIG>, the second side viewed at <NUM>° from the first side view illustrated in <FIG>. <FIG> shows the view clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration.

<FIG> shows a linear view of the outer expandable member <NUM> cut along a centerline B-B indicated in <FIG> and <FIG> and flattened. A portion of the outer expandable member <NUM> as indicated in <FIG> can be configured as illustrated in <FIG> and further as illustrated in <FIG>. For instance, radiopaque markers <NUM> can be staggered as illustrated in greater detail in <FIG>. Connecting arms <NUM> can be tapered and otherwise configured as arms <NUM> illustrated in greater detail in <FIG> and <FIG>. Struts and joints of the outer expandable member <NUM> can be shaped and otherwise configured to correspond to joints and struts <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> illustrated in <FIG> and <FIG>.

<FIG> shows a plan view of a distal end of the clot retrieval device <NUM>. <FIG> shows the view clot retrieval device <NUM> as illustrated in <FIG> having the inner expandable member <NUM> removed for the purpose of illustration. <FIG> shows the view of the clot retrieval device <NUM> as illustrated in <FIG> having the outer expandable member <NUM> removed for the purpose of illustration.

<FIG> shows an example outer expandable member <NUM> traversing a lumen having a <NUM>° bend with a radius of curvature rB at the apex of the bend. Because the outer expandable member <NUM> closely follows the bend of lumen, the outer expandable member has a radius of curvature that is approximately equal to the radius of curvature rB of the lumen. <FIG> shows a close-up of a portion of the outer expandable member <NUM> as indicated in <FIG>. The outer expandable member <NUM> includes tapered connecting arms <NUM> between body segments <NUM> configured similarly to the connecting arms <NUM>, <NUM>, <NUM> of the devices <NUM>, <NUM> illustrated in <FIG>. As shown in greater detail in <FIG>, the outer expandable member <NUM> has a curvature with a radius rA at a narrow area of the connecting arm <NUM> that is smaller than the overall radius of curvature rB of the outer expandable member <NUM> around the bend the lumen. In other words, the connecting arm <NUM> provides a bending point for the outer expandable member <NUM>. The flexibility of the connecting arm <NUM> can allow the body segments <NUM> to extend juxtaposed to a lumen (e.g. the illustrated lumen and/or a blood vessel lumen) to a greater extent than a similarly structured outer expandable member having less flexible connecting arms. In one example, the outer expandable member <NUM> can be configured to bend with a curvature having a radius rA at the narrow area of the connecting arm <NUM> of approximately <NUM> millimeters (mm) or greater including <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

<FIG> shows an illustration of a portion of an example expandable member having a radiopaque marker. <FIG> shows a side view of the portion of the expandable member illustrated in <FIG>. Some or all of the markers <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of the devices illustrated and described herein can be shaped similar to the marker illustrated in <FIG>.

<FIG> are radiographic images of an example clot retrieval device according to aspects of the present invention. Radiopaque material in the distal coil, proximal coil, and markers appear dark in the radiographic images.

A clot retrieval device according to the teachings herein can be sized to accommodate a variety of treatment needs. Dimension such as overall length L1 of the outer expandable member, working length L2 of the device, diameter D1 of the outer expandable member D1, and diameter D2 of the inner expandable member can be measured as indicated in <FIG> and <FIG>.

In one example device, when freely expanded, the outer expandable member can have an overall length L1 about <NUM>, a working length L2 of about <NUM>, and a diameter D1 of about <NUM>. The inner expandable member tubular body diameter D2 can measure less than the outer expandable member diameter, preferably about <NUM> and more preferably about <NUM>. Configured as such, the example device can be suitable for treating blood vessels having a diameter between about <NUM> and about <NUM>. The outer expandable member of the example device preferably includes a proximal body segment, exactly one middle body segment, and a distal body segment similar to the proximal body segment <NUM>, middle body segment <NUM>, and distal body segment <NUM> of the device <NUM> illustrated in <FIG>.

In another example device, when freely expanded, the outer expandable member can have an overall length L1 about <NUM>, a working length L2 of about <NUM>, and a diameter D1 of about <NUM>. The inner expandable member tubular body diameter D2 can measure less than the outer expandable member diameter, preferably about <NUM> and more preferably about <NUM>. Configured as such, the example device can be suitable for treating blood vessels having a diameter between about <NUM> and about <NUM>. The outer expandable member of the example device preferably includes a proximal body segment, exactly three middle body segment, and a distal body segment similar to the proximal body segment <NUM>, middle body segments <NUM>, and distal body segment <NUM> of the device <NUM> illustrated in <FIG>.

In some examples, a clot retrieval device according to the teachings herein can be dimensioned such that markers on body segments (e.g. markers <NUM>, <NUM> on body segments <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> illustrated herein) illustrated herein can be separated in the longitudinal direction (in the direction of the longitudinal axis A-A) from one or more markers on an adjacent body segment by about <NUM> when the clot retrieval device is collapsed for delivery across a clot and can be separated by about <NUM> in the longitudinal direction when the clot retrieval device is freely expanded.

<FIG> illustrates an alternative distal portion of an example clot retrieval device described in greater detail in a U. Non-Provisional Patent Application titled "A CLOT RETRIEVAL DEVICE FOR REMOVING CLOT FROM A BLOOD VESSEL" filed concurrently herewith.

In some examples, a clot retrieval device according to the teachings herein can have alternative geometries suitable for clot retrieval devices. For instance, the clot retrieval device can include a distal portion configured as illustrated in <FIG>. The outer expandable member can include a distal body portion configured similar to the distal body portion <NUM> illustrated in <FIG>. Alternatively, the distal portion of the clot retrieval device need not be configured to capture clot fragments and can for instance can have large cell openings or be completely open. Further, in some examples, the clot retrieval device need not include an inner body.

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.

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 pertinent 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 an exemplary 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.

Claim 1:
A clot retrieval device (<NUM>, <NUM>) comprising a collapsed configuration and an expanded configuration and being configured to remove clot from a blood vessel, the device comprising:
an inner expandable member (<NUM>, <NUM>) comprising a first framework of struts (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
an outer expandable member (<NUM>, <NUM>, <NUM>) comprising a second framework of struts (<NUM>, <NUM>) that form closed cells larger than closed cells of the inner expandable member and that at least partially radially surround the inner expandable member,
the outer expandable member comprising a first and a second body segment (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) connected by two connecting arms (<NUM>, <NUM>, <NUM>, <NUM>),
the first body segment being positioned in a proximal direction in relation the second body segment, and characterised by
each of the two connecting arms respectively comprising a tapered shape being wider near the first body segment and narrower near the second body segment.