Patent Description:
<CIT> relates to a medical device that includes a vessel-engaging member attached to a distal end of a delivery wire. The vessel-engaging member includes a plurality of rows, with each row having a plurality of struts arranged in an alternating pattern such that for each row, a first set of vertices is positioned on a proximal side, and a second set of vertices is positioned on a distal side.

<CIT> relates to a connection structure where a first wire is connected to a second wire having a smaller diameter than the first wire with a coupling member interposed therebetween. The distal end of the first wire is inserted through an opening at one end of the coupling member and swaged. The proximal end of the second wire is inserted through an opening at the other end of the coupling member and swaged, the opening having a smaller diameter than the opening at the one end.

Methods of treatment or surgery are not claimed.

The invention, illustrated in <FIG>, will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:.

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 cath 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 invention. 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 expandable members of the designs disclosed 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 (such as Platinum for example) or through a variety of other coatings or marker bands.

Compression of the clot can alter the clot properties and make the clot less amenable to retrieval by making it firmer and "stickier" as described in our <CIT>. The device of this disclosure is intended to facilitate clot retrieval by expanding between the clot and the vessel wall in such a way as to engage with the clot over a significant surface area and do so with minimal compression of the clot. The overall clot compression is minimised because the device is constructed to have rings of high compression with deep strut embedding interspersed with areas of minimal clot compression. A portion of clot can protrude into the area of low compression and can be pinched between the tip of a catheter and the nitinol struts of the device. The pinch is achieved by forwarding a microcatheter or intermediate catheter over the device until a portion of clot is compressed between the tip of the catheter and a crown or strut on the device. This pinch facilitates removal of the clot as it increases the grip of the device on the clot, particularly fibrin rich clots. It may also elongate the clot reducing the dislodgement force by pulling the clot away from the vessel wall during the dislodgement process. It potentially improves retention of the clot during retraction to the access guide catheter or sheath by controlling the proximal end of the clot and preventing it from snagging on a side branch vessel.

The device design to facilitate pinching of an occlusive clot detailed in this disclosure can be incorporated into the full length of the device or more typically in the proximal <NUM>% - <NUM>% of the length of the device. The diameter of this pinch segment can vary from <NUM>% to <NUM>% of the diameter of the target vessel at the position of the occlusive clot, but in the preferred embodiment for the middle cerebral artery, it is more typically <NUM>% to <NUM>% of the target vessel diameter. This disclosure details how the clot pinch can be generated between the microcatheter tip and struts or crowns on a single tubular structure or alternatively the clot can be pinched between the catheter tip and the struts on the outer cage or inner channel of an assembly.

The inner channel of the disclosure may also comprise a portion that compresses an area of the clot in order to form a blood communication channel across the clot. Such a channel serves two key purposes: <NUM>) it reduces the pressure gradient across the clot, thus reducing one of the forces that must be overcome in order to retract the clot and <NUM>) it provides a flow path for oxygenated, nutrient carrying blood to reach the ischaemic area distal of the clot.

All of the devices described herein may also comprise a distal fragment capture portion, such as illustrated in <FIG>, <FIG>, <FIG>, <FIG>. This portion is ideally deployed distal of the clot to prevent the distal migration of any clot fragments that might be liberated during retrieval.

<FIG> show a method of use of a device of this disclosure. A guidewire <NUM> and microcatheter <NUM> are inserted in the vasculature <NUM> and are advanced across the obstructive clot <NUM> using conventionally known techniques. When the microcatheter <NUM> is positioned distal to the occlusive clot <NUM>, the guidewire <NUM> is removed from the vasculature <NUM> to allow the clot retrieval device <NUM> be advanced through the microcatheter. The device <NUM> is advanced in a collapsed configuration until the distal tip of the device reaches the distal end of the microcatheter <NUM>. The microcatheter is retracted while the position of device <NUM> is maintained to deploy the clot retrieval device across the clot <NUM> in a manner that the distal end of the device is preferably positioned distal of the clot <NUM> (<FIG>). The device <NUM> consists of a clot engagement portion <NUM> connected to an elongated proximal shaft portion <NUM>.

The device <NUM> expands so that it engages with the occlusive clot at the proximal end or along its length. The device has segments that have low levels of scaffolding and do not compress the clot but allow the clot to protrude into these low radial force areas. The device <NUM> may be allowed to incubate for a period of time within the clot <NUM> if desired. Prior to retracting the device, the microcatheter can be forwarded distally to pinch a portion of the clot between the tip of the microcatheter and the struts and crowns of the device adjacent to the low radial force area. This pinch provides additional grip and control of the proximal end of the clot during dislodgement and retention back to the access guide catheter or introducer sheath (<FIG>). The relative tension between the device and the microcatheter is maintained by the user during dislodgment and retraction to ensure the pinch on the clot is maintained. While the use of a microcatheter or intermediate catheter to pinch the clot is described as giving additional benefits when used with this disclosure, all the embodiments described here-in can also be used to dislodge and retrieve clots without the use of catheter pinching if required.

Flow arrest in the vessel may be utilised by inflating a balloon (not shown) on the guide catheter as per standard technique. <FIG> illustrates the clot engaged with the device during retrieval into the guide catheter <NUM>. Flow occlusion, aspiration and other standard techniques may be used during the clot retrieval process. The device <NUM> may be rinsed in saline and gently cleaned before reloading in the insertion tool. The device <NUM> may be reintroduced into the microcatheter to be redeployed in additional segments of occlusive clot, if required.

<FIG> show the proximal end of one embodiment of the device illustrated in <FIG>. The device is typically formed from a material with "Superelastic" properties such as nitinol and can be laser cut and expanded from a tube or flat sheet raw material. The self-expanding section of the device <NUM> is connected to a proximal elongated shaft <NUM>. The device of this disclosure is designed to create a clot pinch and generate additional grip between the device <NUM> and the clot <NUM>. The device <NUM> is constructed so that it consists of rings of struts <NUM> which have an adequate radial force to provide good clot embedding, interspersed with areas of low scaffolding and low radial force <NUM>. The longitudinal distance between the rings of struts can vary from <NUM> to <NUM>, but in the preferred embodiment for use in the middle cerebral artery the longitudinal spacing is <NUM> - <NUM>.

While the struts <NUM> embed and provide some scaffolding of the clot, the area with low scaffolding <NUM> allows the clot <NUM> to protrude into this area. After an incubation time, if desired, of typically <NUM> to <NUM> minutes, the microcatheter <NUM> (used to introduce the device or an alternative microcatheter) can be advanced to pinch the protruding clot <NUM> between the tip of the microcatheter <NUM> and the struts and crown <NUM> of device <NUM>. The struts <NUM> achieve good embedding in the clot as the freely expanded diameter of these struts can vary from <NUM>% to <NUM>% of the diameter of the target vessel at the position of the occlusive clot, but in the preferred embodiment is <NUM>% to <NUM>% of the target vessel diameter. In the embodiment shown the connecting struts <NUM> between the rings of struts <NUM> are curved with a reduced diameter towards the mid-section of the strut to minimise the radial force and scaffolding. This feature can also be seen in <FIG>.

Further distal advancement of the microcatheter <NUM> relative to the device <NUM> will further compress the clot <NUM> between the catheter tip <NUM> and the struts of the device <NUM> increasing the pinch on the clot (<FIG>) and the security of the trapped clot segment <NUM>. The user may feel this pinch as a resistance and stop advancing the microcatheter, or alternatively the user may advance the microcatheter a fixed distance over the device (for example <NUM> % to <NUM>% of the device length) before retracting the device and microcatheter together. The relative tension between the device <NUM> and the microcatheter <NUM> needs to be maintained to ensure the pinch between the device and clot does not deteriorate. By retracting the device <NUM> and the microcatheter <NUM> together, the occlusive clot can be dislodged and retracted back into the access guide catheter or introducer sheath and be removed from the patient. This invention is particularly suited to the dislodgement and retraction of clots which have a high fibrin content (typically higher than <NUM>% fibrin content) and other clots which are difficult to dislodge and retrieve with known stent retriever designs and currently may require multiple passes to remove the clot from the vasculature. This invention may also create a clot pinch by advancing an intermediate catheter in the same manner as described here for the microcatheter <NUM>.

<FIG> shows an isometric view of another embodiment of the device. In this configuration the embedding section of the device consists of a ring of cells <NUM>. This ring <NUM> consists of <NUM> circumferential cells in this embodiment. The number of cells in the circumferential ring can vary from <NUM> to <NUM>, but in the preferred embodiment is <NUM> or <NUM> cells. As with the device shown in <FIG>, the portions of the device <NUM> between the embedding cells section have low radial force and a low level of scaffolding. The low level of scaffolding is achieved by minimising the potential surface contact area between the device struts and the clot in this area <NUM>. In this embodiment the connecting struts <NUM> are curved towards the centre-line of the device at the mid-point to further reduce the strut contact force and area with the clot. This low surface contact area and radial force allows the clot to protrude into this section of the device when it is deployed in an occlusive clot. Partial re-sheathing of the device with a microcatheter or intermediate catheter can then pinch this protruding clot between the tip of the catheter and the proximal struts <NUM> of the embedding ring of cells.

<FIG> shows a side view of the device illustrated in <FIG> with a corresponding graph of radial force plotted against device length. The dotted lines <NUM> and <NUM> show how the rings of cells that embed in the clot have a higher radial force compared with the sections <NUM> between the rings. Dotted line <NUM> indicates the reduced radial force of this section.

<FIG> illustrates the outward radial force profile of three devices of this disclosure similar to device <NUM> of <FIG>, when constrained in a lumen of less than <NUM>% of their freely expanded diameters. All three exhibit the generally sinusoidal pattern described previously, but the magnitude (or amplitude) of the radial force peaks and troughs varies along the length of these devices. Profile <NUM> represents a radial force profile that tapers up along the length of the device, with the radial force of the first peak <NUM> being lower than that of subsequent peaks <NUM>-<NUM>. Profile <NUM> represents a radial force profile that tapers down along the length of the device, with the radial force of the first peak <NUM> being higher than that of subsequent peaks <NUM>-<NUM>. Profile <NUM> represents a radial force profile that tapers up and then down along the length of the device, with the radial force of the first peak <NUM> being lower than that of the second peak <NUM>, but the radial force of the last peak <NUM> being lower than that of the second from last peak <NUM>.

<FIG> illustrates what radial force profile <NUM> could look like if the device were constrained instead in a lumen of more than <NUM>% of its freely expanded diameter (<NUM>% for example). In this case we see that the device exerts no outward radial force whatsoever on its constraining lumen in areas either side of the three peaks <NUM>, <NUM>, <NUM> shown. Thus, the device is maintaining its grip on the clot in the area of the peaks, while exerting minimal compression on the clot in the areas between the peaks, which helps to minimize the force required to retract the clot, and thus increases the likelihood of a successful clot retrieval.

The <FIG> also represent the radial pressure of the strut elements of these three different devices. Radial pressure differs from radial force in that it refers to the force per unit area exerted by the device. Thus, if two devices have the same radial force over a given area, and one device has a lower strut surface area than the other in that given area, then the device with the lower strut surface area will exert a higher radial pressure. This is very important for clot grip because radial pressure is what enables a strut to embed itself into the clot material - somewhat akin to the difference between a stiletto heel and an elephant's foot: when standing on soft sand the stiletto heel will sink deeply into the sand while the elephant's foot will not sink as deeply in. For a given level of radial force, the radial pressure of a device can thus be increased by reducing the strut surface area, which can be done by reducing strut width or number of struts.

The effectiveness of this increased radial pressure at clot gripping can be further increased by maximising the angle of the struts to the longitudinal axis of the vessel. The greater the angle of the strut the greater the ability of the strut to grip the clot rather than slide past it. Ideally the strut would approach a <NUM>-degree angle with the vessel axis for optimum grip, but this can be difficult to achieve in practice for a number of reasons. One major reason for this is the fact that the device is typically expanded to only a fraction of its freely expanded diameter when deployed under the clot initially. This is because it is advantageous for the device to be able to expand to a large diameter as it is retracted so that it can retain its grip on the clot and remain in contact with the vessel wall as it is retracted into larger more proximal vessels. The inventors have discovered an effective solution to this problem: namely a two-stage diameter device as shown in various Figs. throughout this disclosure, such as for example <FIG>. The proximal smaller diameter can be used to embed struts firmly in the clot for a secure grip at a steep opening angle, while the larger diameter distal section can expand to remain in contact with the vessel wall and protect against distal migration of the clot as it is retracted into larger vessels. This configuration enables strut angles of the proximal section to be larger than <NUM> degrees, or preferably larger than <NUM> degrees or even more preferably as large as <NUM> degrees to the vessel axis. <FIG> illustrates this point in greater detail.

<FIG> show another embodiment of the device formed from a flat sheet. <FIG> shows a plan view of the device <NUM> which in this embodiment is formed of two rows of cells <NUM> bounded by sinusoidal edges <NUM> and connected by cross struts <NUM>. The device is connected to a proximal shaft <NUM>. <FIG> shows an isometric type view of the device <NUM> deployed in an occlusive clot <NUM> which is located in a vessel <NUM>. A cut away view of the vessel <NUM> has been provided for clarity. A microcatheter <NUM> is shown positioned on the proximal shaft with the tip of the microcatheter located at the joint between the clot engagement section of the device and the shaft. Where the clot <NUM> is in contact with the device <NUM>, portions of clot <NUM> protrude through the cells. <FIG> shows a cross section view of the vessel <NUM>, including the clot <NUM> and the device <NUM>. This view illustrates the clot protruding through the cells of the device <NUM>.

<FIG> is a magnified view of the proximal end of the device <NUM> showing how the clot is pinched as the microcatheter <NUM> is forwarded to partially re-sheath the device in the cut away vessel <NUM>. The protruding portion of the clot <NUM> is trapped between the struts of the device and the microcatheter <NUM>. <FIG> shows the device <NUM> and the microcatheter <NUM> being retracted at the same time, dislodging the body of the clot <NUM> from the vessel <NUM>, due to the pinched grip on the protruding piece of clot <NUM>.

<FIG> show an alternative tubular embodiment of the device of the disclosure. <FIG> show a side view, end view, plan and isometric view of device <NUM>. This device has alternating rings of embedding struts <NUM> with low radial force segments <NUM>, along its length. The preferred embodiment contains between <NUM> and <NUM> struts in a radial pattern for optimum embedding in the clot. The connecting struts <NUM> in section <NUM> in this embodiment are straight for optimum pushability to ensure the device can be delivered through tortuous anatomy.

<FIG> show another embodiment of the disclosure. <FIG> show a side view, plan, end view and isometric view of device <NUM>. This device has alternating rings of embedding cells <NUM> with low radial force segments <NUM>. The preferred embodiment contains between <NUM> and <NUM> cells in a radial pattern for optimum embedding in the clot. The use of a ring of cells instead of a ring of struts in this embodiment may improve clot pinching as the distal ring of struts <NUM> in each segment stays expanded for longer even as the more proximal ring of struts <NUM> is wrapped down by the microcatheter as it advances. This maintains strut embedding in the clot for longer improving the pinch of the clot between the struts and the microcatheter.

<FIG> illustrate an embodiment which consists of an assembly of an outer cage and an inner component. In this embodiment the proximal part <NUM> of the outer component <NUM> is designed to pinch clot in the same manner as described for <FIG> and <FIG> and contains alternating segments of cells <NUM> for embedding in the clot, and segments <NUM> of low radial force and low scaffolding. This proximal part <NUM> of the outer component is joined to a body section <NUM> which 35485942vl has an increased diameter and larger cells <NUM> for additional clot retention as it is retrieved into larger vessel diameters in the Internal Carotid Artery before retraction of the device and clot into the access guide catheter or introducer sheath. The ratio of the body section <NUM> diameter to the proximal section diameter can vary from <NUM>:<NUM> to <NUM>:<NUM>, and in the preferred embodiment is between <NUM>:<NUM> and <NUM>:<NUM>.

<FIG> shows the inner component <NUM> of the assembly. This component contains an elongated proximal strut <NUM> which connects the body section <NUM> to the shaft (not shown). The component <NUM> also contains a fragment protection structure <NUM> and a distal atraumatic tip <NUM>. <FIG> shows how the two components are aligned in the assembly <NUM>. The elongated proximal strut <NUM> is positioned under the proximal part of the outer cage <NUM> so that there is minimal restriction to clot protrusion into the low radial force segments. The body section of the inner component <NUM> is positioned in the body section of the outer component <NUM> and provides a flow channel to break the pressure gradient across the clot and provide flow restoration. The distal fragment protection structure <NUM> sits inside the end of the outer cage which has an open end <NUM> and provides protection against the loss of clot fragments and emboli. <FIG> shows an isometric view of this assembly <NUM>.

<FIG> shows device <NUM> deployed within a clot <NUM> in a vessel <NUM>, illustrating a key advantage of a stepped diameter design such as that of the clot engaging element <NUM> of <FIG>. The relatively high radial force and radial pressure of the struts of the proximal section <NUM> allow the struts <NUM> of the section to embed deeply into the clot, creating clot bulges <NUM> which can subsequently be pinched within cells <NUM> by the advancement of a microcatheter (not shown). In addition, the smaller freely expanded diameter of the proximal section <NUM> means that the struts <NUM> of this section are inclined at a much steeper angle than those of the distal section <NUM>, which enables them to much more effectively grip the clot for secure retraction. The description in relation to <FIG> describes the significance of these strut angles in more detail.

<FIG> shows another configuration <NUM> of the assembly shown in <FIG> where the fragment protection structure <NUM> connected to the inner component <NUM> is positioned distal of the end of the outer cage <NUM>. Ensuring there is a gap between the end of the outer cage <NUM> and the fragment protection structure <NUM> may improve the fragment protection performance particularly as the device is retracted in tortuous vessels. It may also be beneficial as the device is retrieved into a catheter as the fragment protection zone <NUM> will still be fully expanded and provide protection as the outer cage is fully retrieved.

<FIG> is a side view of another outer cage configuration <NUM> where the proximal part <NUM> of the component is designed to pinch the clot as described in <FIG>, when a catheter is forwarded distally. In this configuration the component <NUM> also contains a body section <NUM> for clot retention during retrieval and a distal fragment zone <NUM>. <FIG> shows an assembly <NUM> of the outer cage <NUM> described in <FIG> and an inner channel <NUM>. The inner channel <NUM> in this assembly <NUM> runs the full length of the outer cage <NUM> including under the proximal section <NUM>.

<FIG> shows an inner component <NUM> which consists of a body section <NUM> and a proximal section <NUM> which contains alternating segments of embedding cells <NUM> and low scaffolded areas <NUM> to promote clot protrusion and clot pinching. <FIG> illustrates how this inner channel design <NUM> can be integrated in an assembly <NUM> with an outer cage <NUM>. The outer cage <NUM> has extended proximal struts <NUM> to minimise any obstructions to the clot engaging with the proximal section <NUM> of the inner component.

<FIG> shows another embodiment of the disclosure <NUM> consisting of an assembly of an outer cage <NUM> and an inner channel <NUM>. These two components are connected to a proximal shaft <NUM> and a distal radiopaque tip <NUM>. In this embodiment the inner channel <NUM> is designed to facilitate clot pinching as described elsewhere in this specification by having alternate rings of struts <NUM> for deep embedding in the clot, adjacent to areas of low strut density or scaffolding <NUM>. As this inner component <NUM> is positioned inside of the outer cage <NUM>, there is the potential for the struts of the outer cage to obstruct clot embedding and protrusion in the inner channel <NUM>. To eliminate this issue, the outer cage <NUM> is designed so that the struts of the outer cage align with the struts of the inner channel <NUM>, when the outer cage is partially expanded to the same diameter as the freely expanded inner channel.

<FIG> show a segment <NUM> of the outer cage illustrated in <FIG>. The segment <NUM> is shown expanded to a diameter greater than the freely expanded diameter of the inner channel but below the freely expanded diameter of the outer cage in <FIG>. The 'dog-leg' shape of the strut <NUM> can be seen in the image and this shape strut is repeated around the circumference and along the length to form cells <NUM>. <FIG> shows how the strut shape consists of a short segment <NUM> connected to a longer segment <NUM> at an angle (A) as shown. This angle can vary from <NUM>° to <NUM>° and in the preferred embodiment is <NUM>° to <NUM>°. The short segment of strut <NUM> may also have an increased strut width compared to the longer segment <NUM>. In this configuration the short strut segment <NUM> has a higher expansion force than the longer strut segment <NUM> therefore it will have preferential expansion and the crown <NUM> will open before the crown <NUM> expands. This gives the outer cage a two-stage expansion process with struts <NUM> and crown <NUM> fully expanding before the struts <NUM> and crown <NUM> expand. This two-stage expansion process also results in a radial force profile that reduces when the first stage expansion is complete. This strut configuration can be produced by laser cutting this strut profile form a nitinol tube which has a diameter equal to or greater than the first stage expansion diameter. Alternatively, the part can be laser cut from a smaller tube and the struts constrained in this shape during heat-setting.

<FIG> shows the same outer cage segment as <FIG>. In this image however, the segment <NUM> is at the same diameter as the freely expanded inner channel. This is the same diameter as the end of the first stage expansion step when struts <NUM> are fully expanded but struts <NUM> are still collapsed. <FIG> shows the segment of the inner channel which aligns with the outer cage segment illustrated in <FIG> and <FIG>. As discussed in <FIG> this segment <NUM> contains rings of struts <NUM> and areas of low radial force and strut density <NUM>.

<FIG> shows the outer cage segment <NUM> (described in <FIG>) overlapping the inner channel segment <NUM> (described in <FIG>). The benefit of this design is that the struts of both segments fully align as shown, so there is no obstruction to the strut section <NUM> embedding in the clot. Similarly, there is no obstruction to the clot protruding into cell area <NUM>, thereby facilitating a pinch when the microcatheter is forwarded distally. In addition, as the device is retracted proximally towards the guide catheter or sheath, the outer cage can continue to expand and maintain contact with the clot even as the vessel diameter increases.

<FIG> shows a cell pattern <NUM> beneficial to clot pinching. This pattern <NUM> can be incorporated in a tubular or flat device configuration. When deployed across an occlusive clot in the vasculature, clot protrusion occurs in the large cell area <NUM>. After a suitable incubation time, the microcatheter can be advanced from the proximal side <NUM> to partially re-sheath the device. When the microcatheter contacts the clot protruding into cell <NUM> it forces the clot to move distally in the cell into area <NUM> between the struts <NUM>. The narrowing struts channel the trapped clot towards crown <NUM> creating an improved pinch on the clot between the catheter tip and the device.

<FIG> illustrates a configuration of the disclosure that consists of an assembly <NUM> of multiple tubular components connected in parallel. In the configuration shown two components <NUM> and <NUM> are connected at the proximal end by a strut <NUM> and subsequently to the proximal shaft <NUM>. Both the components shown here, <NUM> and <NUM>, are similar to the embodiments described in <FIG> and <FIG>. The alignment of these components may be staggered as shown in this image and the components may twist around each other along the length. More than two components may be connected together in this manner and the different components may have different diameters or be tapered along the length. The assembly of these components has the potential to improve clot pinching and grip when the device is partially re-sheathed with a microcatheter or intermediate catheter.

<FIG> shows a configuration of the device where the tubular component <NUM> is formed into a helical or spiral shape <NUM> and is connected to a proximal shaft <NUM>. The cut pattern of the component <NUM> is designed to promote clot embedding and grip as described in <FIG> and <FIG>. However in this configuration, the centreline of the component follows a helical track such as that shown in <FIG>, where the track <NUM> follows the surface of a cylindrical mandrel <NUM>.

In another embodiment of the device shown in <FIG>, a flat device <NUM> is formed so that the centreline of the device also forms a helical path in this case. This device can be formed by laser cutting the required strut pattern <NUM> from a tube or by cutting a flat sheet and then wrapping the flat part around a cylinder prior to heat-setting. Therefore, the device has a similar shape to wrapping a wide ribbon around a cylinder. When this device is deployed across as occlusive clot, the clot can protrude into the areas of low strut density but also into the central lumen of the helical coils. On device retraction this can improve clot grip and dislodgement performance and can also facilitate clot pinching if a microcatheter or intermediate catheter is forwarded distally over the device until it contacts the clot. The embodiment <NUM> shown has a flat cross section in the body part <NUM> of the device. The helical body section is connected to a proximal shaft <NUM> and a distal fragment protection structure <NUM> with a distal tip <NUM>. <FIG> shows another device embodiment <NUM> similar to <FIG> except with a curved or profiled cross section shape for the body segment <NUM>. <FIG> illustrate different examples of cross section shapes that may be incorporated in this configuration of the disclosure. <FIG> shows a flat cross section <NUM>, <FIG> shows an 'S' shaped cross section <NUM> and <FIG> shows a curved cross section <NUM>.

<FIG> shows another helical configuration of the device <NUM> with a curved cross section similar to that shown in <FIG>. The laser cut or wire formed clot engagement section <NUM> is connected to a proximal shaft <NUM>. A microcatheter can be used with this device to pinch the clot and generate improved grip on the clot as described in <FIG>. When the micro or intermediate catheter is forwarded over the device to pinch the clot it can follow the centreline of the vessel or alternatively it can follow the centreline of the device and follow a helical track as shown in <FIG>. If the catheter <NUM> follows the centreline of the vessel <NUM> during re-sheathing it can generate good pinching of the clot in the luminal space <NUM> within the helical coil. Alternatively, if the catheter <NUM> follows the centreline of the device <NUM> as shown, it can generate good pinching of the clot in the cells of the cut pattern <NUM>. <FIG> shows an embodiment of the device <NUM> that is constructed from two helical components <NUM> and <NUM> to form a double helix type construction.

<FIG> illustrates another embodiment of the disclosure <NUM> where the proximal part of the device <NUM> is designed to facilitate clot pinching if required, similar to that described in <FIG>. The body section <NUM> is also similar to that described in <FIG>, however in this embodiment the connection <NUM> between the proximal and body sections can elongate under tension. This facilitates the stretching of the clot during dislodgement by the device. The proximal end of the clot will be pinched and constrained on the proximal part of the device <NUM> while the distal end of the clot will be positioned on the body section <NUM>. When the device is retracted the proximal end <NUM> will move first pulling the proximal end of the clot. If the distal end of the clot is stuck in the vessel, the body section of the device will remain static and the connector <NUM> will elongate. This will also elongate the clot peeling it from the vessel wall and reducing the dislodgement force. When the tension in the connector <NUM> equals the dislodgement force of the distal section of the clot the remainder of the clot will start moving. In this embodiment the elongating connector <NUM> is formed of a coil spring, however in another embodiment this elongating element could form part of the cut pattern of the outer cage.

<FIG> illustrate another embodiment of the device. <FIG> shows the device <NUM> in the freely expanded configuration. In this iteration of the disclosure the proximal part of the outer cage <NUM> is configured to promote clot embedding and clot protrusion to facilitate clot pinching. The body section <NUM> of the outer cage has an increased diameter compared to the proximal section, to ensure good clot retention as the device is retracted past bends and branches in the vasculature. The outer cage has an open distal end with radiopaque markers <NUM> shown on the distal crowns. The inner component in this assembly consists of a wire <NUM> connecting the fragment protection structure <NUM> with the proximal joint <NUM>. In the freely expanded configuration there is distinct gap between the distal struts of the outer cage <NUM> and the leading edge of the fragment protection structure <NUM>. This gap can vary from <NUM> to <NUM> and in the preferred embodiment will range from <NUM> - <NUM>.

<FIG> shows the same device as <FIG> except in this image the device <NUM> is at the diameter of the target vessel at the location of the occlusive clot. At this diameter the leading edge <NUM> of the fragment protection structure <NUM> is located inside the outer cage <NUM> and proximal of the distal crowns <NUM>. This change in position of the fragment protection structure <NUM> relative to the outer cage <NUM> is due to the length differential of the outer cage <NUM> in the freely expanded configuration and at reduced diameters. Positioning the fragment protection structure inside the outer cage at small diameters minimises the parking space required distal of the clot for device deployment. In addition, positioning the fragment protection structure <NUM> distal of the outer cage <NUM> during device retraction in large vessels and during retrieval into a guide or intermediate catheter improves the efficacy of the fragment protection.

<FIG> shows a method of use of the device embodiment described in <FIG>. Device <NUM> is deployed across the clot <NUM> using standard interventional techniques and positioned so that the distal end of the device <NUM> and fragment protection structure <NUM> is positioned distal of the clot <NUM>. The device <NUM> also contains a clot pinch portion <NUM> and is connected to an elongated proximal shaft portion <NUM>.

Device image <NUM> shows the device in the vessel after the microcatheter <NUM> has been advanced to generate a pinch between the clot <NUM> and the proximal portion of the device <NUM>. At this diameter in the target vessel location, the distal fragment protection structure <NUM> is partially inside the outer cage <NUM>.

Device image <NUM> shows the device as it is retracted back into a larger diameter vessel. As the vessel diameter increases, the diameter of the outer cage <NUM> also increases and the outer cage length shortens. This creates a gap between the proximal edge <NUM> of the fragment protection structure and the distal end of the outer cage <NUM>. This facilitates the capture of any fragments or emboli <NUM> liberated during the dislodgement and retrieval process. The clot <NUM> is still held pinched between the distal tip of the microcatheter <NUM> and the device <NUM>.

Device image <NUM> also illustrates the effectiveness of the fragment protection structure <NUM> as it captures the clot fragments <NUM> and <NUM> released from the clot body <NUM> during the retrieval process.

The device <NUM> shown in <FIG> is another embodiment of the device shown in <FIG> where a tubular component <NUM> is formed in a helical or spiral configuration and connected to a proximal shaft <NUM>. In this configuration the centreline of the component forms a helical track which follows the surface of a tapered or cylindrical mandrel as shown in <FIG>. The diameter of the tubular component can vary from <NUM> to <NUM> and in the preferred embodiment ranges from <NUM> to <NUM>. The diameter of the cylindrical mandrel that the helix track follows can vary from <NUM> to <NUM> and in the preferred embodiment ranges from <NUM> to <NUM>. The pitch of the helix can vary from <NUM> to <NUM> and in the preferred embodiment ranges from <NUM> to <NUM>.

The helical configuration of this device provides performance benefits for clot dislodgement as the device engages more with the clot than for a straight configuration. The clot embeds deeper in the cells and between the struts of the device improving the grip of the device on the clot. This occurs due to the helical shape which positions portions of the device away from the surface of the vessel and in the body of the clot. This is shown in <FIG> where the spiral device <NUM> is deployed within the clot <NUM> in the neurovascular vessels <NUM>. The device <NUM> is deployed as per standard procedure for deploying a stent retriever, by delivering it through and then retracting the microcatheter <NUM>. In one method of use, the device <NUM> can be retracted directly to dislodge the clot <NUM> and retrieve it into the access catheter <NUM>. Aspiration may be utilised during the procedure and flow arrest may be provided by inflating the balloon <NUM> on the access catheter <NUM>. Alternatively, after deployment of the device <NUM> in the clot, the microcatheter <NUM> can be forwarded again to partially re-sheath the device <NUM> and generate a pinch on the clot between the distal tip of the microcatheter and the struts and crowns of the device <NUM> as described elsewhere in this specification. The device, microcatheter and clot can then be retracted as a unit into the access catheter, utilising flow arrest and aspiration, if required.

The increased depth of clot embedding in a device with a helical or corkscrew configuration is particularly useful for obtaining a pinch on clots in difficult vessel tortuosity and in vessel bifurcations as shown in <FIG> where the effective diameter of the bifurcation (D4) is larger than the diameter of the proximal (D1) or distal (D2, D3) vessels. This is further illustrated in <FIG> and b, where <FIG> illustrates a straight tubular component <NUM> deployed in a clot <NUM> within a vessel <NUM>. <FIG> shows improved engagement and embedding in the clot <NUM> when the tubular component <NUM> (with the same diameter as component <NUM> in <FIG>) is formed with a helical configuration. The helical configuration increases the depth the device <NUM> engages within the clot and also the surface area of the device in contact with the clot.

<FIG> shows a helical tubular component <NUM> deployed in a clot <NUM> which is located in a bifurcation of the anatomical vessels <NUM>. The microcatheter <NUM> can be forwarded to re-sheath the device <NUM> until the physician feels a resistance to movement indicating that the clot has been pinched in the device. The microcatheter <NUM>, device <NUM> and clot <NUM> can then be removed simultaneously while maintaining the pinch between the device and clot.

The helical tubular component shown in <FIG> is particularly good at generating a pinch on clots which are difficult to dislodge and retrieve from the vessel such as organised clots with a moderate to high fibrin content. <FIG> shows a device <NUM> which can be used for dislodgement and retention of all clot types. This device <NUM> incorporates a helical tubular component <NUM> which can be used to generate a pinch on the clot by partial re-sheathing with the microcatheter as described previously. The outer cage component <NUM> also engages with the clot on deployment providing additional grip for dislodgement and retention of the clot as the device is retracted proximally to the intermediate catheter, guide catheter or sheath. The outer cage component <NUM> provides dislodgement and retention capability for a full range of clot types including soft erythrocyte rich clots and hybrid clots with varying elements. The helical component <NUM> also provides additional radial force to the inner surface of the outer cage <NUM> helping it to expand within the clot on deployment. The outer cage component <NUM> has distal radiopaque markers <NUM> to mark the distal end of the component under fluoroscopy. The radiopaque markers <NUM> would typically consist of wire coils, rivets or inserts produced from Platinum, Tungsten, Gold or a similar radiopaque element.

The outer cage <NUM> is connected to the proximal shaft <NUM> in this configuration by a proximal strut <NUM>. This strut <NUM> has minimal impact on the pinch performance of the helical component <NUM> and can be positioned inside or outside of the proximal section of the helical tube <NUM>. To generate a pinch on the clot with this device, it can be partially re-sheathed with a microcatheter, diagnostic or intermediate catheter until the physician feels a resistance to pushing the catheter any further distal over the device. At this point the physician knows he has a successful pinch and the catheter and device can be removed with the clot as a unit. If no resistance is felt or a pinch is not generated then the device <NUM> can be retrieved as a standard stent retriever to retrieve the clot to the access catheter. The radiopaque marker <NUM> is visible under fluoroscopy and is an indicator to the physician on when to retrieve the device as a standard stent retriever, i.e. re-sheath the device with the microcatheter (not shown) until a definite resistance (pinch) is felt or until the tip of the microcatheter is aligned with marker <NUM>. Then retrieve the device as per standard procedure.

This device <NUM> also incorporates a fragment protection feature <NUM> to capture clot fragments or emboli that may be generated during the clot dislodgement and retrieval. In this configuration the fragment protection feature <NUM> is an integral part of the helical component <NUM> and is positioned distal to the outer cage component <NUM> when fully expanded. A distal radiopaque tip <NUM> is connected to the end of the fragment protection feature <NUM>.

For additional clarity the outer cage component <NUM> and helical component <NUM> shown in the device assembly <NUM> in <FIG> are illustrated separately in <FIG>. The outer cage component <NUM> in <FIG> has a mid-section construction in this configuration similar to that described in our <CIT>. Distal markers <NUM> are connected to the distal crowns of this section for visibility under fluoroscopy and radiopaque marker <NUM> is positioned on the elongated proximal strut <NUM>. The radiopaque marker <NUM> can be formed from a coil of radiopaque material and can be bonded, welded or soldered in place. Alternatively it can be formed from a ring of radiopaque material and be radially crimped, or formed from a flat sheet and be riveted in an eyelet on the strut. The proximal collar <NUM> can be used to assemble the outer cage component <NUM> and the helical tube component <NUM> (shown in <FIG>) to the proximal shaft of the device (not shown).

<FIG> illustrates the helical component <NUM> that is included in the assembly <NUM> in <FIG>. For clarity no strut details are shown along the body section <NUM> of the component <NUM> in this image. Proximal struts <NUM> and the proximal collar <NUM> used for device assembly are shown. The fragment protection section <NUM> and the distal radiopaque marker <NUM> are also shown. In this configuration the body section <NUM> has a fixed diameter along its length, however in other configurations (not shown) the diameter may increase or decrease along the length. Similarly in other configurations the helical diameter and pitch may vary along the length or the component may have a combination of straight and helical sections. In addition to the pinch capability of this component, it also provides inner channel functionality such as; immediate restoration of blood flow on deployment, breaking the pressure gradient across the clot, facilitating contrast flow and distal visualisation and acting as an aspiration channel for distal emboli. The strut and crown pattern of the device <NUM> may vary along the length of the body section <NUM> so that the proximal portion provides a pinch capability while the mid and distal portions are more densely scaffolded to provide inner channel functionality.

Another embodiment of the disclosure is shown in <FIG>. This device <NUM> is also an assembly of an inner helical tubular component <NUM> and an outer cage <NUM>. In this configuration the fragment protection feature <NUM> is integral to the outer cage <NUM>. The outer cage <NUM> and the helical component <NUM> are connected to the proximal shaft <NUM> at the proximal joint <NUM>. The distal radiopaque tip <NUM> is joined to the outer cage <NUM> in this assembly.

<FIG> shows another embodiment of the device shown in <FIG>. In this device <NUM>, the proximal section <NUM> is configured to pinch the clot when partially re-sheathed by the microcatheter. As before the proximal struts <NUM> have large opening angles and the cell size promotes clot protrusion to facilitate pinching between the microcatheter and the device <NUM> during re-sheathing. The mid-section <NUM> is configured to expand to a larger diameter than the proximal section to provide clot grip and retention during retraction of the clot past vessel bends and branches. The proximal <NUM> and mid sections <NUM> have different strut lengths and cut patterns and hence different radial force characteristics. In one embodiment the radial force of the proximal section <NUM> is larger than the corresponding radial force of the mid-section <NUM>, for a fixed deployment diameter (e.g. <NUM>), while in another embodiment the radial force of the mid-section <NUM> is larger than the radial force of the proximal section <NUM> for the same deployment diameter.

<FIG> illustrates a typical strut cut pattern of the pinch portion of any of the devices detailed in this disclosure. The struts <NUM> have a large opening angle relative to the longitudinal vessel axis which promotes improved clot grip as the greater the angle of the strut to the direction of movement, the greater the ability of the strut to grip the clot rather than slide past it. Similarly the inner diameter of the crown <NUM> is increased to also improve clot grip by maximising the length of the crown that is near perpendicular to the direction of travel within the clot. The length of the strut connector <NUM> increases the total cell area <NUM> to provide rings of cells in the device with low radial force and low strut surface area to promote clot embedding and protrusion into these cells. When the device is re-sheathed with the microcatheter the protruding clot is pushed against the struts <NUM> and into the crown space <NUM> trapping it and pinching it in position.

Another embodiment of the device cut pattern is shown in <FIG>. In this configuration the strut shape and bend angle <NUM> adjacent to the crown <NUM> is sized so that on re-sheathing with the microcatheter <NUM>, the adjoining struts close together <NUM> creating another pinch point to help grip the clot that is protruding into the cell area (not shown).

As described in <FIG>, the larger the crown inner diameter in the cut pattern the longer the portion of the crown which is near perpendicular to the longitudinal axis of the vessel (and the direction of clot movement), the better the clot dislodgement capability. <FIG> shows a crown configuration which allows the crown diameter to be maximized while enabling the device to be wrapped into the loaded configuration for delivery through the microcatheter to the target vessel location. To minimize the wrapped diameter, the crowns <NUM>, <NUM> and <NUM> are offset along the longitudinal axis so that in the collapsed configuration the crowns fit into the space either side of the short connector, for example <NUM>. To generate this crown offset the adjoining struts <NUM> and <NUM> have different lengths.

<FIG> shows another embodiment of the device where the cut pattern is configured so that the crown <NUM> maintains its full diameter during re-sheathing by the microcatheter <NUM> so that the maximum quantity of clot can be pushed from the cell <NUM> into the crown space <NUM> by the microcatheter tip <NUM> creating a pinch. <FIG> shows an embodiment of the cut pattern where the proximal facing crowns <NUM> are similar to those described in <FIG> where the crown space <NUM> is maximised for improved clot pinching. In this configuration the distal facing crown diameter <NUM> is reduced as the crown is not required for clot pinching and the reduced diameter may facilitate a lower re-sheathing force and increased radial force in the adjacent struts <NUM>.

<FIG> shows an embodiment of the device where the proximal facing crowns <NUM>, <NUM> have a larger diameter than the distal facing crowns <NUM> for improved clot pinching as detailed in <FIG>. The alternating rings of cells along the longitudinal axis of this device have different areas with cell <NUM> having a larger area than <NUM>. Hence more clot is likely to embed and protrude into cell <NUM>. The clot protruding into the cell <NUM> will get pushed towards crown <NUM> by the microcatheter when re-sheathing. To ensure this re-sheathing is smooth with good tactile feedback to the physician, the length of strut <NUM> is increased to reduce the feeling of 'bumping' as the catheter goes from low radial force segments to high radial force segments. In addition the length of strut <NUM> is shortened to increase radial force in the ring of struts which is supporting crown <NUM>. This keeps the crown <NUM> expanded for longer during re-sheathing by the microcatheter increasing the pinch effectiveness.

<FIG> show a strut / crown configuration which promotes clot pinching along the length of the strut. <FIG> shows the struts <NUM> and <NUM> in the freely expanded configuration. Strut <NUM> is produced so that it contains a series of bends <NUM>, <NUM> and <NUM> approaching the crown <NUM>. Similarly strut <NUM> contains a series of matching bends <NUM>, <NUM> and <NUM>. As the device is re-sheathed in the microcatheter, the diameter of the device reduces and the struts move closer together. <FIG> illustrates that as the diameter reduces, the bends in the struts interlock creating pinch points such as between points <NUM> and <NUM>, and between <NUM> and <NUM>. This helps to grip the protruding clot which is embedded between the two struts as shown in <FIG>. In <FIG> part of the clot <NUM> protrudes into the cell between the struts. As the device is re-sheathed by the microcatheter (not shown), struts <NUM> and <NUM> move closer together generating a pinch on the protruding clot <NUM>. This clot pinching improves device efficacy with enhanced clot dislodgement capability and safe clot retrieval into the access catheter.

Another embodiment of the disclosure is shown in <FIG>. This figure illustrates the profile and outer shape of the device <NUM> but does not show the strut pattern for clarity. In this embodiment the proximal section of the device <NUM> is formed into a spiral configuration as described in <FIG>. This proximal section <NUM> is also configured to pinch the clot when partially re-sheathed by the microcatheter. As before the struts have opening angles and crowns to facilitate clot pinching and the cell size promotes clot protrusion to further improve pinching between the microcatheter and the device during re-sheathing. The body section <NUM> is configured to expand in a cylindrical or uniform shape to provide clot grip and retention during retraction of the clot past vessel bends and branches. The body section is also particularly suited to the grip and retention of softer clot with red blood cell content in the range of <NUM>-<NUM>% but particularly clots with red blood cell content greater than <NUM>%. In this configuration the device is effective at dislodging and retaining fibrin rich and red blood cell rich clots by gripping the fibrin rich clot by partial re-sheathing with the microcatheter over the proximal section <NUM>, while gripping and retaining the softer or heterogeneous clots by the body section <NUM>. The device <NUM> shown in this figure is connected to a proximal shaft (not shown) at the proximal joint <NUM> and has a fragment protection zone <NUM>. The proximal spiral section <NUM> is connected to the body section <NUM> at <NUM>. This connection may be centred and be concentric with the body section or may be eccentric, for example aligning with the outer surface of the body section. The flared section <NUM> between the proximal tubular section and the body section can include large cell openings to facilitate clot migrating into the body section for improved retention and fragment protection.

<FIG> shows an end view of the device <NUM> illustrated in <FIG> when viewed from direction 'A' as shown. In this figure the spiral outer surface <NUM> has a larger diameter (Ø 'S') than the body section diameter <NUM> (Ø 'B'). In other embodiments (not shown) the spiral outer diameter may be equal or smaller than the body section diameter. The spiral outer diameter is typically between <NUM> and <NUM> diameter and in the preferred embodiment is between <NUM> and <NUM>. The body section diameter can vary from <NUM> to <NUM> and in the preferred embodiment is between <NUM> and <NUM>. The body section is shown in a cylindrical configuration in this embodiment however this section may also be formed into a spiral or curved shape with a different pitch, tubing diameter and spiral diameter to the proximal section.

The embodiment <NUM> shown in <FIG> has a similar shape to the device illustrated in <FIG> with additional strut and construction details. This embodiment is shown connected to a proximal shaft <NUM> by the proximal struts <NUM>. The proximal section <NUM> is formed in a spiral configuration and the body section <NUM> is formed in a cylindrical shape. The distal end of the device forms a cone shape to provide fragment protection capabilities. A radiopaque coil or marker <NUM> is added to the distal tip for visibility under fluoroscopy. An additional radiopaque marker <NUM> is added to the device at or near the transition from the spiral section to the body section. This marker <NUM> highlights the end of the spiral section <NUM> and can be used to distinguish the optimum point to stop re-sheathing with the microcatheter. This radiopaque marker may also be used to align the device with the proximal face of the clot for red blood cell rich clots. Similarly a radiopaque coil (not shown) on the distal end of the shaft <NUM> can be used to align the spiral pinch section <NUM> with the proximal face of fibrin rich clots. The proximal spiral section is typically <NUM> to <NUM> in length and in the preferred embodiment is between <NUM> and <NUM> in length. Additional radiopaque markers can be added along the spiral section to provide increased visual feedback and clarity for the re-sheathing process with the microcatheter. <FIG> also illustrates the cell openings <NUM> at the diameter transition from the spiral tube to the body section which are designed to facilitate clot entering partially or fully inside the body section <NUM>.

<FIG> shows another embodiment <NUM> of the device where only the shaft <NUM> and the outer shape of the spiral and body sections <NUM> are shown. In this embodiment the radiopaque marker <NUM> which distinguishes the end of the spiral section <NUM> is mounted on an extension <NUM> to the proximal shaft <NUM>. This shaft extension <NUM> continues distal of the proximal joint <NUM> which connects the spiral section to the shaft <NUM>.

<FIG> shows a partial plan view of the embodiment <NUM> detailed previously in <FIG> - d and illustrates the large cell area <NUM> which promotes clot protrusion into the device so that it can be pinned against struts <NUM> and <NUM> when the device is re-sheathed with a microcatheter. In <FIG> the device <NUM> is shown deployed in a clot <NUM> which is located in an arterial vessel <NUM>. The device <NUM> is connected to a proximal shaft <NUM>. On deployment of the device, the ring of struts and cells <NUM> embed in the clot, while the clot section <NUM> positioned over the large open cell section <NUM> protrudes into the device. The large open cell section promotes clot protrusion into the device, minimising clot compression and subsequent increase in friction with the vessel wall <NUM>.

<FIG> illustrates how the protruding section <NUM> of the clot <NUM> is pushed against the ring of struts and crowns <NUM> by the catheter tip <NUM> to generate the grip on the clot to facilitate dislodgement and retrieval from the vasculature.

The disclosure disclosed here is more effective and reliable at generating a clot grip and pinch than existing stent retriever technology when re-sheathed with a catheter. <FIG> illustrates what happens when an existing stent retriever device <NUM> (prior art) is re-sheathed with a microcatheter. <FIG> shows stent retriever <NUM> deployed in a clot <NUM>. Strut embedding occurs in the clot <NUM> and some clot protrudes into the open cells <NUM>. A typical stent retriever has an outer diameter in the range of <NUM> to <NUM> and as the device <NUM> is re-sheathed as shown in <FIG>, it contracts and pulls away from the clot <NUM>. Therefore as the microcatheter <NUM> is advanced, the struts <NUM> which were embedded in the clot <NUM> pull away from the clot surface and the clot protrusion in the cell is lost allowing the microcatheter to advance fully, re-sheathing the device underneath the clot. <FIG> shows how the strut length <NUM> and crown opening angle <NUM> dictate the re-sheathing angle <NUM> of the device, as it is re-sheathed by catheter <NUM>. The greater this angle <NUM> from the vertical, the more likely the device struts will pull away from the surface of the clot during re-sheathing. The length <NUM> is the distance from the catheter tip that the device diameter starts to contract as the catheter is forwarded. This length increases as the re-sheathing angle increases (from vertical), reducing the contact of the device struts with the clot.

In comparison to <FIG> of existing stent retriever technology, <FIG> show an embodiment of the disclosure deployed in a clot. <FIG> illustrates a device <NUM>, similar to that described elsewhere in this patent, deployed in a clot <NUM>. The rings of struts <NUM> embed into the clot and the clot <NUM> protrudes into the large open cells <NUM>. As the device is re-sheathed with a catheter as shown in <FIG>, the strut length, crown configuration and radial force profile along the device length maintain strut embedding in the clot and clot protrusion in the cells as the catheter tip approaches. Therefore the clot <NUM> is still protruding in the device cell during the re-sheathing process and is pushed against the adjacent strut <NUM> and crown <NUM>, pinching it in position. Crown <NUM> is also supported by the ring of struts <NUM> to ensure it stays expanded and embedded in the clot for longer during the re-sheathing process. This performance characteristic is reflected in the reduced re-sheathing angle (from vertical) shown in <FIG> and the significantly reduced length <NUM> showing that the device diameter does not contract except in the immediate vicinity of the catheter tip. This feature is further facilitated by the alternating higher and lower radial force profile along the device length as described previously in <FIG>.

The preferred embodiment of this device has an outer diameter of <NUM> to <NUM> which facilitates shorter strut lengths which allow higher crown expansion angles during the re-sheathing process than standard stent retrievers which typically expand to <NUM> to <NUM>. This is illustrated in <FIG> where <FIG> shows the expanded struts <NUM> of a <NUM> cell conventional stent retriever with a <NUM> outer diameter, which has been unrolled into a 2D configuration. This same device is shown in <FIG> when contracted to a <NUM> diameter, showing the strut length <NUM> and how the crown opening angle has reduced from <NUM> in <FIG> to <NUM> in <FIG>. In comparison a strut configuration of the disclosure is shown in <FIG> illustrating the large expanded angle <NUM> of the struts plus the large crown ID <NUM> to facilitate pinching. This device is still effective at <NUM> diameter as the clot engagement and retention is provided by pinching the clot between the microcatheter tip and the crown and struts of the device rather than pinning the clot partially or fully against the vessel wall by the device to maintain strut embedding and clot engagement.

The strut configuration shown in <FIG> provide additional benefits to help generate a pinch and dislodge occlusive clots. The strut pattern of the device <NUM> in <FIG> is shown unrolled into a 2D configuration. When the device <NUM> is re-sheathed with a microcatheter, the outer diameter reduces causing the neck point <NUM> to move towards the opposite neck point <NUM>. This can help grip the clot protruding in the cell <NUM> and maintain the clot in this position as the microcatheter advances and pushes the clot against crown <NUM>, pinning it and generating a pinch grip. <FIG> further illustrates how the neck points <NUM> close together providing additional grip on the clot (not shown) that is positioned between the microcatheter tip <NUM> and the crown <NUM>, to facilitate pinching and also enhance the grip and retention of the clot as it is retracted past bends and branches to the access catheter.

Referring to <FIG> there is illustrated another device <NUM> according to the disclosure which has in some features which are similar to the devices described above. The device <NUM> comprises a proximal pinch section <NUM> and a distal section <NUM> which in this case is of generally cylindrical or barrel shape having a larger diameter than the proximal section. The distal barrel section <NUM> has distal radiopaque markers which in this case comprise two platinum / tungsten coils <NUM> which are attached to the distal most ends of two of the struts that form the distal barrel section <NUM>. Further radiopaque markers <NUM>, which may be of gold, are located at the transition between the proximal pinch section <NUM> and the distal barrel section <NUM>. The markers <NUM> can give an indication under fluoroscopy of how far to re-advance the microcatheter during the re-sheath process. The radiopaque markers <NUM> are preferably offset longitudinally to minimise the profile of the device. Similarly, the radiopaque markers <NUM> are also preferably offset longitudinally to minimise device profile.

The device <NUM> is preferably formed from a single tube of a shape memory material such as Nitinol which is laser cut to form the strut pattern. The distal barrel section <NUM> is flared outwardly to form the barrel shape so that this section forms a larger diameter than that of the proximal pinch section <NUM> in the expanded configuration illustrated. The device <NUM> also has a proximal joint <NUM> between the proximal end of the pinch section <NUM> and an elongate shaft on which the device is mounted. The proximal joint is described in detail below.

In the expanded deployed configuration the diameter of the distal barrel section is typically about <NUM> (within a range of <NUM> to <NUM>) and the diameter of the proximal pinch section is about <NUM> (within a range of <NUM> to <NUM>).

As will be partially apparent from <FIG> and <FIG> the length of at least some of the proximally facing struts <NUM> is larger than the length of at least some of the distally facing struts <NUM>. The differences in strut length ensure that the radial force applied to a clot by the pinch section varies to achieve good grip on the clot whilst facilitating clot retrieval in association with a microcatheter.

The proximal pinch section <NUM> of the device ensures engagement with difficult clots such as fibrin-rich clots whilst the larger distal section <NUM> provides improved retention of soft clot, improved clot retrieval into a guide catheter tip and stability of the device on deployment and during retrieval as the device is retracted back through the vasculature and into a guide or sheath.

Referring to <FIG> there is illustrated another device <NUM> according to the disclosure which is similar to the device of <FIG> and comprises a proximal pinch section <NUM>, a distal section <NUM>, distal marker coils <NUM> and radiopaque markers <NUM>. In this case the proximal pinch section <NUM> is heat set into a spiral shape. The spiral may have the following features: spiral pitch - <NUM> (within a range of <NUM> - <NUM>); spiral outer diameter - <NUM> (within a range of <NUM> to <NUM>); and the spiral typically may form a <NUM>° curve, or range from <NUM> to <NUM>°.

A longitudinal centre axis of the distal barrel section <NUM> may be offset from a centre line of the spiral to assist in achieving uniform (low strain) connection between the sections. In this device the distal end of the spiral section is orientated so that it is perpendicular to the proximal face of the barrel section. In this orientation both the struts connecting the spiral section to the barrel section are equal length and have equivalent levels of strain regardless of the cut pattern orientation on the heat forming mandrel. In other iterations the spiral section may be orientated at an angle to the barrel section. The outline shape of the spiral and barrel sections are illustrated in <FIG> shows a former tool that may be used to shape the spiral and the flare the tube from which the spiral is made outwardly to form the distal barrel section <NUM>.

The barrel section of the devices of <FIG> is shown in more detail in <FIG>. The staggering of the radiopaque markers <NUM>, <NUM> is particularly apparent in <FIG> and the longitudinal staggering of the markers <NUM> is clearly apparent in <FIG>.

<FIG> illustrate an alternative distal barrel section of devices of the disclosure. In this case the barrel section has a closed distal end <NUM> for fragment protection. Fragment protection may be provided or enhanced by a distal filter which may be mounted on a separate shaft extending through the device.

The configuration and location of the radiopaque markers <NUM>, <NUM>, <NUM>, <NUM> are more clearly visible in <FIG>.

The proximal end of the pinch section of the device of the disclosure is in some cases attached to a shaft using a mechanical locking system. The locking system may include a first receiver for a shaft and a second receiver for one or more proximal struts of the pinch section. The shaft may include a feature such as a step for engagement with the locking system. In some cases the locking system is configured to accommodate radiopaque markers. In some cases an end of a single strut may be configured for engagement with the locking system. In other cases the locking system is configured to engage with the ends of two or more struts.

Referring to <FIG> there is illustrated a proximal joint <NUM> between a proximal strut <NUM> and a shaft <NUM> as per the invention. The proximal strut <NUM> in this case has a slot <NUM> and terminates in two legs <NUM>, one of which is slightly longer than the other. The increased length of one leg <NUM> makes it easier to align and position the collar during assembly of the proximal joint. In another iteration of the design the two legs <NUM> are replaced with a single strut (not shown). Additional slots and connecting struts may be included in <NUM> to improve the mechanical lock between the component and adhesive applied to the joint.

The shaft <NUM> has an enlarged end <NUM> which defines a step with the main part of the shaft <NUM>. A collar <NUM> is slidable over the shaft end <NUM> and has distally facing slots <NUM> to accommodate the body of the strut end in the region of the slot <NUM>. The collar <NUM> also has proximally facing slots <NUM>, so that the positioning of the collar <NUM> on the shaft <NUM> is not orientation specific. Part of the enlarged portion <NUM> of the shaft <NUM> is received in the slot <NUM> in the strut <NUM>. The proximal face of the shaft end <NUM> engages with the proximal face of slot <NUM> to transmit load during pinching and retraction of the device during use. When the collar <NUM> is in position, the slots <NUM> constrain the proximal strut <NUM> so that the proximal face of slot <NUM> cannot disengage from the shaft end <NUM>. This mechanical lock ensures the ultimate joint strength of the assembly is based on material properties and not on adhesive or weld joint strength, as the joint requires the component materials to fail for the joint to separate.

To form the proximal joint, the collar <NUM> is first slid over the enlarged portion <NUM> of the shaft and advanced along the shaft <NUM> to the position illustrated in <FIG>. The proximal strut <NUM> is then positioned so that the enlarged portion <NUM> of the shaft is received in the slot <NUM> of the strut as illustrated in <FIG>. The lock collar <NUM> is then advanced to lock the strut <NUM> to the shaft <NUM> as illustrated in <FIG>. Adhesive is then applied to the joint. A radiopaque marker may then be positioned adjacent to the joint. The configuration ensures that a low profile joint is achieved which has a robust mechanical lock with the tensile strength to facilitate resistant clot retrievals in challenging anatomy. Under compressive loading during delivery of the device through a microcatheter, the distal end of the enlarged portion <NUM> may engage with the distal face of slot <NUM> providing a face to face transfer of compressive load.

Another proximal joint <NUM> is illustrated in <FIG> which is similar to the proximal joint of <FIG>. In this case the joint <NUM> is configured to accommodate the ends <NUM> of two proximal struts, which are jointed to a shaft <NUM> having an enlarged portion <NUM>. A lock collar <NUM> is used to lock the shaft <NUM> to the strut ends <NUM>. This configuration increases the face to face contact area between the struts of the expanded distal portion <NUM> and the proximal face of the enlarged portion of the shaft <NUM> improving the ability of the joint to transfer load. The collar <NUM> has <NUM> slots to ensure the struts <NUM> cannot disengage from the enlarged portion of the shaft <NUM>.

Claim 1:
A clot removal device comprising a proximal joint (<NUM>) between a proximal strut (<NUM>) and a shaft (<NUM>), wherein the proximal strut comprises a slot (<NUM>), and wherein the shaft comprises an enlarged end (<NUM>) which defines a step with a main part of the shaft, wherein a part of the enlarged end of the shaft is configured to be received in the slot, and wherein the device further comprises a collar (<NUM>) configured to be slidable over the enlarged end (<NUM>), and characterised in that the collar comprises distally facing slots (<NUM>) configured to accommodate a body of the proximal strut (<NUM>).