Patent Description:
Formation of thrombus in the vasculature can lead to clots over time, putting a patient at risk of ischemic stroke. There are a variety of techniques to remove clots, including aspiration and mechanical thrombectomy. The latter technique involves utilizing a mechanical device to grip and withdraw the clot. These mechanical devices are often referred to as clot retrieval devices or stentrievers - the latter term is often used since the devices were originally construed as stents reconfigured for clot retrieval purposes. Many clot retrieval or stentriever devices have a distally open configuration (e.g., like a stent) to enable the devices to grip and remove clots from the vasculature.

There are a number of issues with using traditional mechanical thrombectomy devices. Visualization of the thrombectomy device is important to ensure the device is appropriately positioned relative to the clot in order to capture the clot. However, it can be difficult to design a fully imageable radiopaque thrombectomy device since radiopaque materials are often difficult to work with.

Proper opening of a thrombectomy device can also be difficult, especially in the smaller vasculature regions of the brain. Thrombectomy devices typically utilize a shape memory material, and this shape memory property is responsible for device expansion upon release from a delivery catheter. However, as the devices are sized bigger or longer (e.g., to capture larger clots), and/or as the devices are utilized in smaller vessels thereby augmenting the resistance from the vessel wall, it can be difficult to get the thrombectomy device to expand completely, thereby negatively affecting clot capturing capability.

Additionally, the traditional open distal-end design of many thrombectomy devices or stentrievers can result in thrombus or clot shearing off and being thrown distally into the bloodstream during the retrieval procedure. This can result in clot or thrombus formation in other regions of the vasculature.

There is a need for a thrombectomy device which addresses these and other shortcomings.

In patent publication <CIT>, a device is disclosed that is adapted for deployment in a body vessel for collecting floating debris and emboli in a filter. The device includes a collapsible proximally tapered frame for operably supporting the filter between a collapsed insertion profile and an expanded deployment profile. The tapered collapsible frame includes a mouth which is sized to extend to walls of the body vessel in the expanded deployed profile to seal the filter relative to the body vessel for collecting debris floating in the body vessel.

In patent application publication <CIT>, an apparatus is disclosed that is operable in different modes to perform various functions for treating a body lumen. The apparatus includes a shaft including a proximal end, a distal end, a lumen extending therebetween, and a balloon on the distal end having an interior communicating with the lumen. The apparatus includes a valve on the distal end that selectively opens or closes an outlet communicating with the lumen. With the valve open, fluid introduced into the lumen exits the outlet into a body lumen. With the valve closed, fluid introduced into the lumen expands the balloon. The apparatus also includes an actuator for axially compressing the balloon, and a helical member extends between ends of the balloon interior that expands the balloon from a contracted condition to an expanded helical shape when the actuator is activated.

A mechanical clot or thrombus retrieval device is described. The retrieval device can be considered as a thrombectomy device or stentriever.

The present invention is defined by the appended claims only, in particular by the scope of appended independent claim <NUM>. References to "embodiments" throughout the description which are not under the scope of the appended claims merely represents possible exemplary executions and are therefore not part of the present invention.

In some embodiments, a retrieval device with enhanced opening characteristics is described. In one embodiment, a coil or spring element is used along an interior length region of a retrieval device and helps to ensure proper opening or expansion of the retrieval device. In one embodiment, a coil or spring element is used along an interior length region of a retrieval device and helps to ensure proper collapse of the retrieval device. In one embodiment, the coil or spring element is radiopaque to aid in visualization of the device.

In some embodiments, a retrieval device with a closed distal shape is described. In one embodiment, a retrieval device utilizes one or more tubular or cylindrically shaped elements with a closed-end configuration.

In some embodiments, methods of manufacturing a retrieval device is described. In one embodiment, a tubular or cylindrically shaped element with a closed-end configuration is manufactured. One or more of these components are connected together in order to manufacture a retrieval device.

In some embodiments, a retrieval device with at least a partially closed distal shape is described. A distal end of the clot retrieval device includes a plurality of radial segments where at least some of the radial segments are inwardly oriented in order to create a distal radial constriction, useful in trapping thrombus.

In one embodiment, a method of manufacturing a clot retrieval device is described. A tubular or cylindrically shaped element is created with an open distal end configuration, and a plurality of radial segments. At least some of these radial segments are then oriented radially inward in order to create a distal radial constriction.

In some embodiments, a retrieval device with radiopaque properties useful for imaging of the device is described. In one embodiment, a radiopaque spring element is used along an interior length region of a retrieval device. The radiopaque spring element can have additional benefits, such as helping to ensure proper opening and/or collapse of the device. In one embodiment, a radiopaque plating or marker component is added to selective areas of a retrieval device. In one embodiment, a tubular spiral radiopaque element is used on selective areas of a retrieval device. In one embodiment, a radiopaque coiled element is used on selective areas of a retrieval device. In one embodiment, a retrieval device has one or more coining holes which are filled with a radiopaque element.

In some embodiments, methods of manufacturing a retrieval device is described. In one embodiment, a plating or marker component is placed over selective regions of a retrieval device. In one embodiment, a tubular spiral radiopaque element is placed over selective regions of a retrieval device. In one embodiment, a retrieval device is manufactured with one or more coining holes and radiopaque material is filled into the coining holes. In one embodiment, a spring component is placed within an interior region of a retrieval device - in one embodiment, the spring component is radiopaque.

These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which:.

Mechanical retrieval, thrombectomy, and stentriever devices were discussed in the background section above and are useful for physically grasping and withdrawing the clot or thrombus from the vasculature. For the purposes of this specification, removal device, retrieval device, thrombectomy device, and stentriever shall be used interchangeably and shall generally refer to the same concept of a mechanical retrieval device used to grasp and remove clot or thrombus from the vasculature. Clot and thrombus shall also be used interchangeably.

The device embodiments described herein can be used to capture and/or retrieve clot, thrombus, as well as foreign body objects. Foreign body objects include elements that are not natural to the vasculature space, such as medical devices. One example is an embolic coil which may be used to occlude an aneurysm but may migrate from the aneurysm to another area of the vasculature, thereby creating a clot risk.

The current state of the art of these devices suffer from a number of shortfalls. One issue is proper visualization of the devices. Radiopaque components can be used to make a device viewable during a procedure, and it is desirable to visualize a substantial or an entire length of a thrombectomy device in order to ensure the device is sufficiently positioned with respect to the clot or thrombus to enable its capture. However, it can be difficult to make a retrieval device that is sufficiently radiopaque (and therefore imageable) along all or most of the device. One way would be to make the entire device of a metallic radiopaque substance (e.g., tantalum, palladium, platinum, or gold). However, these radiopaque materials exhibit poor shape memory properties, and good shape memory characteristics are needed to ensure the device properly collapses into its delivery state when within a catheter, and then expands to its natural expansion state when released from the catheter. Also, these radiopaque materials are typically expensive and create an economic challenge in developing a cost-effective retrieval device.

Ensuring proper opening of the thrombectomy device is important to ensure the device is completely opened to capture any clot or thrombus. Though a shape memory material (e.g., nitinol) can be used to create a thrombectomy device, it can still be difficult for the device to sufficiently expand under certain conditions - such as along a tortuous section of the vasculature, or within smaller blood vessels (e.g., those in the neurovasculature). Neurovasculature vessels, in particular, can be very small and tortuous making clot removal difficult in these areas. Other characteristics including but not limited to size of the blood vessel, device design (e.g., sizing in comparison to the vessel, thickness of the device, material selection) can contribute to difficulties in a thrombectomy device sufficiently expanding within the vasculature.

The following embodiments address these issues by providing a radiopaque imageable device which also has enhanced opening and/or closing characteristics to make a more usable thrombectomy device.

<FIG> illustrates a device <NUM> according to one embodiment utilizing a coiled or spring element <NUM>. Device <NUM> includes a number of structural struts <NUM> extending along all or a portion of the device. These struts <NUM> define the outer perimeter of device <NUM>, such that any clot or thrombus may initially contact the struts <NUM> during a clot retrieval procedure and then be enclosed partially or completely within the area of the struts <NUM> during the retrieval procedure. The struts <NUM> in their aggregate extend from one end of the device <NUM> to the other end and thus span the entire length of the device, although struts <NUM> may be composed of various strut segments spanning various lengths of the device which, which, in their aggregate, span the entirety of the device <NUM>. In one embodiment, the device <NUM> (including struts <NUM>) is composed of a shape memory metallic material, such as nitinol or stainless steel.

Device <NUM> includes proximal and distal terminal regions 108a, 108b. The proximal terminal region (e.g., 108a) is connected to an elongated delivery pusher (not shown) - and the pusher is gripped and pushed by a user to navigate the connected thrombectomy device <NUM> through a delivery catheter and to push the device <NUM> out of the delivery catheter and into the vascular treatment location.

<FIG> shows a device <NUM> in its radially expanded and longitudinally shortened configuration, which it adopts when not constrained within a delivery catheter. This is due to heat set, expansile shape memory that is built into the device <NUM> to allow the device <NUM> to adopt an expansile configuration when released from a delivery catheter. <FIG> shows the same device <NUM> in its radially constrained and longitudinally elongated configuration, which it adopts when within a delivery catheter (not shown).

In one embodiment terminal regions 108a, 108b are tubular radiopaque marker bands (e.g., tantalum, platinum, palladium, gold, or composite material like platinum-iridium) useful in visualizing the ends of device <NUM>. In another embodiment, terminal regions 108a, 108b are thickened cylindrical regions utilizing similar material as the rest of the device <NUM> (e.g., shape memory metallic material). Terminal regions 108a,108b can either be solid such that there is no through-lumen therethrough, or alternatively can each include an inner hole or through-lumen.

As can be appreciated from <FIG> (and particularly <FIG> which details these elements), thrombectomy device <NUM> has a device body comprising a cylindrical or tubular medial section <NUM>, and tapered proximal and distal end sections 112a, 112b connected to medial section <NUM>. The cylindrical or tubular medial section <NUM> represents a larger diameter section of device <NUM>, while the tapered ends 112a and 112b represent smaller diameter end regions or sections of device <NUM>. The tapered ends 112a, 112b are in turn connected to terminal regions 108a, 108b.

In one embodiment shown in <FIG>, coil or spring element <NUM> is connected directly to structural struts <NUM> along one or more locations along the struts <NUM> in order to attach the coil or spring element <NUM> to the struts <NUM> of device <NUM> (note: these attachment points are not explicitly shown in the Figures). This attachment can be done in a variety of ways, including via welding, adhesive, or mechanical retention elements (e.g., a wound coil, clip, or tubular band to provide interconnection). In one example, coil or spring element <NUM> is attached to struts <NUM> along or near a medial/middle section of the device <NUM>, so as to provide the retention primarily along a center region of the device <NUM>. In another example, the coil or spring element <NUM> is attached to struts <NUM> near proximal and distal ends of the device <NUM> (e.g., along the tapered end sections 112a, 112b) so as to provide retention primarily along both ends of device <NUM>. In another example, coil or spring element <NUM> is attached along struts <NUM> located along a proximal, medial, and distal section of device <NUM> so as to provide retention along a substantial length of device <NUM>.

Coil or spring <NUM> preferably spans an entirety or a majority of the length of the device <NUM>, as shown in <FIG>. In one preferred embodiment, coil or spring <NUM> is radiopaque, and is therefore visible through radiographic imaging techniques and will allow an associated length and diameter of thrombectomy device <NUM> (i.e., the length of the thrombectomy device associated with the radiopaque coil/spring <NUM>) to be visible during the clot retrieval procedure. Radiopaque material such as tantalum, gold, platinum, palladium, or a composite material such as drawn-filled tubing with a radiopaque core and nitinol jacket can be used to create coil or spring <NUM>. In another example, a good shape memory material such as nitinol or stainless steel is coated with a radiopaque material (such as the radiopaque materials outlined above) to create a radiopaque coil/spring <NUM> which also has strong shape memory properties. Where coil or spring <NUM> is radiopaque and extends along a majority of entirety of the device, this will help visualize most of all of the length of device <NUM>, which is important in confirming proper placement relative of the thrombectomy device relative to a clot. In one example, coil or spring <NUM> extends at least through the tubular portion of device <NUM> (e.g., not necessarily through the tapered proximal and distal regions 112a, 112b - where these tapered end regions are shown in <FIG>), so that at least the tubular portion of the device which comprises the larger diameter region of the device is visible. Since coil or spring <NUM> spans an interior region of device <NUM>, it can be considered as an inner element or an inner elongated element of device <NUM> which adopts a radially expanded and longitudinally shortened configuration (e.g., <FIG>) and a longitudinally elongated and radially compressed configuration (e.g., <FIG>).

Coil or spring <NUM> can be manufactured in a number of ways. In one example, a wire is wound around a cylindrical mandrel to create a plurality of adjacent windings. This shape is then optionally heat treated to establish an expanded, shape memory coil-like or spring-like shape. In this way, the coil or spring has this shape imprinted via shape memory, which further helps the coil or spring <NUM> adopt its nominal or expansile, non-elongated shape as the device <NUM> is delivered out from the delivery catheter. However, even if no such heat treatment is undertaken, the coil or spring <NUM> will have some degree of stored potential energy when device <NUM> is in its elongated, <FIG> shape (e.g., in a delivery catheter) due to the natural tendency of an object to resist deformation of its shape. Therefore, when device <NUM> is released from the delivery catheter, this stored energy will be released, causing coil or spring <NUM> to adopt its more expansile shape and in turn also helping propel device <NUM> into its expansile shape of <FIG>. This relationship is also mutual, as the built-in shape memory of device <NUM> will allow it to expand upon release from a delivery catheter (e.g., <FIG> shape) into its expansile (e.g., <FIG>) shape. Since the coil or spring <NUM> is connected to the device, it too will adopt its expansile shape as the device <NUM> adopts its expansile shape.

Coil or spring <NUM> adopts a radially expanded and longitudinally shortened shape when device <NUM> is in its radially expanded and longitudinally shortened shape, and a radially contracted and longitudinally elongated shape when device <NUM> is in its radially contracted and longitudinally elongated shape, as can be appreciated in the context of <FIG>. This occurs, at least, since the coil or spring <NUM> is connected to one or more strut portions <NUM> of the device <NUM>, however, as will be explained later, the coil or spring <NUM> can be connected in various ways to the device <NUM> in various embodiments.

In one embodiment, similar to what is shown in <FIG>, when device <NUM> is in its expanded shape, coil or spring <NUM> is close or substantially flush with an inner surface of struts <NUM> (e.g., similar in diameter to the expanded shape diameter of device <NUM>). One such advantage to this configuration is that imaging over an entire width or diameter of device <NUM> is possible due to the radiopacity of the coil or spring <NUM> and since the coil or spring <NUM> is substantially close to the struts <NUM> which define the periphery of device <NUM>.

In one embodiment, coil or spring element <NUM> extends around an entire inner periphery of thrombectomy device <NUM> when the thrombectomy device is in its expanded shape (i.e., near or adjacent the struts <NUM> of the device <NUM>, around an entire inner periphery of device <NUM>). Such a configuration may offer some benefits in terms of providing a clear passage radially within device <NUM> for clot or thrombus retention. In some embodiments, coil or spring element <NUM> can utilize projecting components (e.g., barbs), or a chemical binding agent (e.g., a retentive coating) to help ensure any clot that contacts coil or spring element <NUM> is retained by the coil or spring element to augment clot retention of the device. Similarly, struts <NUM> can also utilize these retentive elements to help augment clot retention.

In one embodiment, coil or spring <NUM> adopts a substantially flat or linear shape when in its elongated configuration (meaning, when thrombectomy device <NUM> is in its elongated and radially collapsed configuration). In such a configuration, windings of coil or spring <NUM> would be sparsely spaced apart and limited in diameter so as to not be as noticeable (e.g., in comparison to its expanded, <FIG> shape). In another embodiment (e.g., shown in <FIG>), coil or spring <NUM>, in its elongated configuration, is not completely substantially flat or linear and still has more of a traditional coil or spring-like shape with noticeable windings, even when extended or stretched.

In another embodiment, coil or spring element <NUM> assumes a less radially expansive configuration when device <NUM> is in its expanded state - such that coil or spring element <NUM> adopts an elongated configuration of <FIG> when collapsed, and a radially expanded configuration not substantially different from the elongated configuration. This configuration has some utility for a relatively radially small thrombectomy device <NUM> which does not radially expand to a significant degree when in its expanded configuration compared to its extended/radially collapsed/delivery configuration (e.g., its configuration when within a delivery catheter).

Wire diameter of coil or spring <NUM> (i.e., the diameter of the wire itself which is wound to create the coil or spring <NUM> shape) can vary depending on the desired performance characteristics. A thicker versus thinner wire diameter will affect force exerted against struts <NUM> (in an embodiment where coil or spring <NUM> is configured to contact the struts <NUM> in an expanded shape). A thicker versus thinner wire diameter will also potentially either resist or augment expansion as device <NUM> adopts its expanded shape - depending on other characteristics such as, for example, how and where the coil or spring <NUM> is attached to device <NUM> and the degree of tension coil or spring element <NUM> is under when in its elongated (e.g., <FIG>) configuration.

Thrombectomy device <NUM> of <FIG> has a closed, funneled, or tapered proximal and distal end shape (e.g., sections 112a, 112b, as discussed earlier). Traditional or prior art stentrievers generally have an open distal end shape, as discussed earlier. There are some disadvantages to this open distal end shape - mainly that it is relatively easy for clot to dislodge and escape from the distal end of the device during the retrieval procedure. This creates a risk of clot migrating elsewhere further downstream in the vasculature, just sending the clot from one location to another. One advantage of the embodiment is the closed distal end shape which helps prevent this issue. In practice, the struts will emanate from one terminal region 108a (e.g., at a proximal end of the device <NUM>) and end at another terminal end region 108b (e.g., at a distal end of the device <NUM>). Though device <NUM> is illustratively shown from its side profile view, a number of struts are configured to form the structure. Thus, by way of example, a plurality of struts (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>) radially project from element 108a. These struts can be connected at equidistant intervals around the circular shape, as shown in <FIG> where <NUM> struts 102a-102d emanate from terminal region 108a. This arrangement is shown from a different perspective in <FIG>, where struts 102a-102d extend from terminal region 108a. A similar number of struts terminate at opposing terminal region108b. In between the two terminal end regions 108a, 108b, the struts can combine to form a condensed number of struts (e.g., a pair of the struts condense into one strut along a length of the device <NUM>), or branch off to form a greater number of struts (e.g., a pair of the struts branch off into <NUM> struts, and then condense down into two struts near their termination at terminal region 108b) - this is shown in more detail in <FIG> where the struts condense and branch off along a length of a device. This can be useful to create a complex and varied strut shape especially in the middle of a thrombectomy device, which is the portion of the device most likely to contact clot or thrombus. Engagement or contact with the device struts <NUM> can help device <NUM> engage the clot or thrombus, and in this way having larger strut surface coverage can provide potential benefits in clot engagement and retrieval.

Another embodiment, shown in <FIG>, utilize a coil or spring <NUM> affixed at each end directly to terminal regions 108a and 108b of clot retrieval device <NUM> (e.g., via welding, adhesive, or mechanically through a screw interface). Since coil or spring <NUM> is connected directly to the terminal ends of the device <NUM>, coil or spring <NUM> will automatically adopt an elongated configuration when device <NUM> is in an elongated and compressed state (e.g., in a delivery catheter), and then a shortened and radially expansile configuration when device <NUM> is in an expanded shape (e.g., upon being released from the delivery catheter). Optionally, coil or spring <NUM> can also be attached at one or more locations along the struts <NUM> of device <NUM> (similar with respect to the embodiments of <FIG>, described earlier) to further augment attachment strength between coil or spring <NUM> and device <NUM>. These additional attachment locations can also affect mechanical properties of the device (e.g., increased resistance to expansion or further augmenting expansion) and can therefore be used to further alter desired mechanical properties of device <NUM>.

Coil or spring <NUM> can be affixed to a hole or through-lumen location of terminal end regions 108a, 108b (where those terminal regions utilize an inner hole or through-lumen). Alternatively, where terminal regions 108a, 108b are solid (i.e., having no such hole or through-lumen), coil or spring <NUM> can be directly attached to solid terminal regions 108a, 108b.

<FIG> show another embodiment where a first elongated end element 104a is connected to terminal region 108a, and a second elongated end element 104b is connected to terminal region 108b. Elongated end elements 104a, 104b can either be a wire or tubular structure. Coil or spring <NUM> is connected to each elongated end element 104a, 104b (e.g., either at the most inwardly-facing location of each end element 104a, 104b or somewhere along each end element 104a, 104b). In this manner, coil or spring <NUM> is indirectly connected to each end of device <NUM>, and in this manner coil or spring <NUM> expands as the device <NUM> expands, and elongates as device <NUM> elongates/adopts a compressed shape. Optionally, coil or spring <NUM> may also be connected at one or more strut locations <NUM> along the device <NUM>.

End elements 104a, 104b can be affixed to a hole or through-lumen location of terminal regions 108a, 108b (where those terminal regions utilize an inner hole or through-lumen). Alternatively, where those terminal regions 108a, 108b are solid (i.e., having no such hole or through-lumen), elongated end elements 104a, 104b can be directly attached to solid terminal regions 108a, 108b.

Another similar embodiment (not pictured) can utilize a telescoping elongated element extending through the length of device <NUM> and connected to each terminal end region 108a, 108b. The telescoping nature of the elongated element allows it to extend and contract as the clot retrieval device, respectively, elongates and expands. In one embodiment, the telescoping element is radiopaque to allow the length of the device to be visualized. In one embodiment, a radiopaque coil or spring <NUM> is connected at one or more locations along the telescoping element to provide or augment imaging. Radiopaque coil or spring <NUM> may solely be connected to this telescoping elongated element, or can be connected to struts <NUM> of device <NUM>, or can be connected to both the telescoping elongated element and struts <NUM> of device <NUM>.

The configurations and explanations and different examples and embodiments of coil or spring <NUM> as described in the embodiments of <FIG> above generally apply to the embodiments of <FIG>, <FIG> as well since only the mechanism of attachment between coil or spring <NUM> and device <NUM> is different. Therefore, the coil or spring <NUM> can be configured in a variety of ways regarding at least attachment to the device (e.g., whether or not attached to struts <NUM>), degree of radial expansion and/or longitudinal elongation in an expanded vs collapsed configuration, degree to which the coil or spring is tensioned or utilizes shape memory to affect expansion and/or contraction of device <NUM>, etc..

One advantage to a coil or spring shape for element <NUM> is that there is the ability to adopt more of a radially collapsed/stretched shape when elongated (e.g., see <FIG>, <FIG>, <FIG>). Coil or spring <NUM> will tend to store energy or be tensioned in this stretched configuration. The built-in potential energy along a coil or spring shape when tensioned or stretched can also help propel the device <NUM> into its expanded shape (e.g., see <FIG>, <FIG>, <FIG>) when the device <NUM> is released from a delivery catheter. This offers advantages in promoting proper opening of the device, for instance where device <NUM> is being deployed through tortuous anatomy or through a small blood vessel (e.g., in the neurovasculature) where there are many compressive forces surrounding the device <NUM>. The stiffness or k-factor of coil/spring <NUM>, length of coil or spring element <NUM>, and the number of windings along coil or spring element <NUM> are all variables that can be tweaked in order to customize the mechanical properties of thrombectomy device <NUM>. K-Factor is a component of Hooke's law which correlates the force needed to compress or elongate a spring with the distance of compression, represented as the letter "k" in the equation F = kx. K-factor (associated with spring stiffness) is a property of the material used as well as the width and length of the wire used to create a coil or spring <NUM>. In one preferred example discussed earlier, coil or spring <NUM> is composed of radiopaque materials (specific examples mentioned earlier), though other examples can utilize traditional shape memory materials such as nitinol or stainless steel - all these materials will have different k or stiffness values - thus the material can be specifically selected to generate a desired k or stiffness profile. Similarly, the length and the diameter of the wire used in shaping coil or spring <NUM> can be adjusted to affect the stiffness characteristics of the coil or spring (and thus, the k-factor). These properties can also affect how much, if any, resistance coil or spring <NUM> provides to elongation (e.g., when a thrombectomy device is being collapsed upon placement into a delivery catheter). These properties can also affect how much coil or spring <NUM> helps either urge expansion into a radially expanded shape, or resists such expansion. The number of attachment points and attachment locations between coil or spring <NUM> and the rest of device <NUM> (e.g., where and how they are attached, whether and where they are attached along the struts <NUM>, etc.) can also affect how coil or spring <NUM> affects device <NUM> as device <NUM> radially expands or longitudinally elongates.

One advantage of a configuration where a coil/spring <NUM> is located substantially near or adjacent struts <NUM> when in its expanded state (whether directly attached to struts <NUM> or not) is that coil/spring <NUM> can be used to apply outward force against the struts to help prop open the struts <NUM> as the device <NUM> adopts its expanded configuration - especially in a scenario where a coil/spring <NUM> is tensioned and therefore has some degree of imparted potential energy in its compressed and elongated state which is released upon deployment. In other words, upon release from a delivery catheter, the built-in shape-memory of the device along with the force/tension integral to coil/spring <NUM> will expand coil/spring <NUM>, in turn aiding in the expansion of the overall device <NUM>. In this way, in some embodiments coil or spring <NUM> can be considered as a tensioning member. In a similar way as to how tensioning coil/spring <NUM> can augment expansion of device <NUM>, imparting shape memory into coil or spring <NUM> may provide a similar benefit.

The various embodiments presented thus far may utilize different attachment mechanisms between coil or spring element <NUM> and device <NUM> which can impact how coil/spring element <NUM> affects the device <NUM>. For instance, in the context of <FIG>, coil or spring <NUM> is directly affixed to one or more struts <NUM> of the device <NUM>. In this example, the radial expansion of struts <NUM> after delivery will in turn affect the radial expansion of coil or spring <NUM>. However, since coil or spring <NUM> is likely tensioned or otherwise storing energy in its collapsed state (e.g., in the <FIG> configuration), coil or spring <NUM> will also exert force against struts <NUM> during expansion. Similarly, if coil or spring <NUM> has shape memory imparted, this shape memory will cause the coil or spring <NUM> to exert force against struts <NUM> as coil or spring <NUM> adopts its own heat-set expansile shape.

In the context of <FIG> where the coil or spring <NUM> is attached, at least, to each end of device <NUM>, the heat set expansion of device <NUM> will cause coil or spring <NUM> adopt its own expanded shape (e.g., see <FIG>). However, since coil or spring <NUM> is naturally tensioned in its elongated, <FIG> shape or otherwise stores energy (e.g., due to imparted shape memory), the release of this energy upon expansion will also impact the shape of the device <NUM> and may help it adopt its radially expansile shape of <FIG>. This relationship is similar in the context of <FIG>, where coil or spring <NUM> is attached to both ends of device <NUM> via linkage with elongated end elements 104a, 104b. Additional attachment of coil or spring <NUM> to the strut elements <NUM> of device <NUM> will only enhance the physical connection and the associated interplay between coil or spring <NUM> and the rest of device <NUM>.

The embodiments shown and described herein and with respect to <FIG>, can utilize additional features. For instance, a plurality of coils or springs <NUM> utilizing one or more of the attachment parameters shown and described above can be utilized. Furthermore, coil or spring <NUM> itself, in an alternative configuration, can be composed of a series of connected coils or springs connected together along its length to create a complete coil or spring structure.

Thrombectomy devices are typically configured as a single element (e.g., a single tubular element) which is used to engage a clot. While this can be suitable for smaller clots, it can be difficult to use such a design to engage a larger or longer clot, which can span beyond the length of a single tubular element. The following embodiments address this issue by utilizing a plurality of clot engaging elements, which can offer benefits in retrieving larger clots.

<FIG> illustrates a thrombectomy device <NUM> according to one embodiment, utilizing a plurality of thrombectomy components 120a-120c. Three components 120a-120c are shown illustratively, but in other embodiments fewer (e.g., <NUM>) or more (e.g., <NUM>-<NUM>) components can be used along the device <NUM>. Each thrombectomy component 120a, 120b, 120c is configured as its own mechanical capture object, where these components are connected in order to create an elongated device <NUM>, which is longer than the component objects 120a-120c. Each thrombectomy component 120a-120c can be considered as its own device body, thereby the device <NUM> has a plurality of connected device bodies.

The thrombectomy components 120a-120c can be connected together in various ways. Two separated component 120a, 120b are shown in <FIG>. Each component has a proximal terminal region and a distal terminal region at either end of the component, these terminal end regions are configured similarly to the end regions described in the embodiments for <FIG>. In this way, component 120a has a proximal terminal region 108a1 and a distal terminal region 108b1 and component 120b has a proximal terminal region 108a2 and a distal terminal region 108b2.

In the context of <FIG>, the "left" side of the Figures can be thought of as representing a proximal part of the device <NUM>, while the "right" side of the Figures represent a distal part of the device <NUM>. In this way, the right side (e.g., the right-most component 120c) will be the first one deployed into the vasculature. An end region of one thrombectomy component 120a is linked to an adjacent end region of the next thrombectomy component such that the components become linked to create the elongate device <NUM>. In the context of <FIG>, terminal end region 108b1 is linked to an adjacent terminal end region 108a2. Where more components are added (as shown in <FIG>), this linking continues along the length of the device <NUM>.

In one example, one end region of a thrombectomy component is welded to an adjacent end region of an adjacent thrombectomy component to link all the thrombectomy components 120a-120c of device <NUM> together. In another example, a linking rod or pin with flared ends is placed within the radius of the two adjacent terminal regions (e.g., element 108b1 and 108a2) such that the two thrombectomy components are thereby linked. This linking rod or pin comprises a tubular medial section smaller than an internal diameter of the end region (i.e. smaller than an internal passage that passes through terminal end regions 108b1 and 108a2) but the ends of this rod or pink are larger than the diameter of the internal passage to retain the link/pin within between two of the thrombectomy components (e.g., one linking pin between components 120a and 120b, and another linking pin between components 120b and 120c). This design, as well as other thrombectomy device embodiments, is discussed in more detail in <CIT> which is hereby referenced to. The use of a linking pin would necessitate the use of a terminal region (e.g., elements 108b1, 108a2) which each utilize an inner hole or through-lumen to allow passage of the link.

The attachment method between the thrombectomy component can affect the design and functionality of thrombectomy/clot retrieval device <NUM>. For instance, welding the ends together will attach the components 120a-120c in a manner so as to preclude independent rotation of one component (e.g., component 120a) relative to another (e.g., component 120b). However, a linking pin concept as discussed earlier will enable independent rotation of each component 120a-120c. This is because rather than being directly attached to each other, the components are individually linked in pairs through a linking pin. This offers advantages in certain operative situations. For instance, where a clot is located along a tortuous bend of the vasculature and independent rotation of each component can allow the device to shear clot off the vasculature wall to aid in its capture.

In other embodiments, various attachment methods or techniques can be combined. For instance, some thrombectomy components can be linked together via the linking pin concept, and other thrombectomy components can be linked together via welding or other direct attachment. For instance, components 120b and 120c can be linked together via the linking pin concept which allows component 120c to rotate independently of component 120b. Components 120b and 120a can then be directly attached (e.g., welded) to each other, such that these components cannot independently rotate relative to each other. With this design, only component 120c can rotate independently of the other components 120a, 120b. This is just an illustrative example, and designs utilizing more components (e.g., more than three) can utilize various combinations of attachment to allow selective rotation of one or more components. In some embodiments, it may be more desirable to have independent rotation along one or more distally located components to help urge these components into secure engagement with the clot to aid in the retrieval process.

In another embodiment, the thrombectomy device which includes a plurality of thrombectomy components (e.g., 120a-120c) is created in a different manner rather than linking a plurality of separate components together. Instead, one contiguous elongated device <NUM> is created which is composed of a plurality of shapes (e.g., components 120a-120c). However, instead of the components being separately linked, the complete device itself is created over a tubular mandrel having a series of tubular sections and tapered sections in between to create a singular elongated element with a variable profile along its length. This configuration can offer some benefits in not requiring separate elements to be linked, and therefore having a contiguous structure.

The embodiments presented discussed thus far and presented in <FIG> can be created in a variety of ways. In one example, a flat sheet of a shape memory metallic material (e.g., nitinol or stainless steel) is laser cut to create a flat sheet comprising a plurality of struts and gap or open regions in between the various struts. This shape as then heat set over a cylindrical mandrel to adopt a generally tubular configuration. The funneled or tapered proximal and distal end shapes can be created by utilizing a similar funneled or tapered mandrel shape which those specific sections are placed over. Alternatively, a tubular sheet material is laser cut to create the overall strut pattern utilized in the thrombectomy device. In this way, the thrombectomy device is already in its tubular shape prior to the laser cutting step.

The embodiments presented thus far generally utilize a closed distal end design, as opposed to the typical open-ended distal shape common to existing stentrievers. <FIG> discloses another embodiment utilizing a generally closed distal end design, but achieving this configuration in a different way. <FIG> shows a flat sheet thrombectomy device <NUM> which is laser-cut to result in a plurality of struts <NUM>. Similar to the other embodiments, there is a first terminal region 118a configured similar to the other embodiments described earlier. This flat sheet is later placed around a tubular mandrel to impart the tubular implant device shape, a portion of this tubular final shape is generally shown in <FIG>. The device <NUM> includes a number of end components <NUM>, six (<NUM>) end components <NUM> are shown in <FIG> although fewer or more can be used. For instance, <NUM> - <NUM> end components can be used. Each end component <NUM> has a generally parabolic-type shape, though other shapes can be used in different embodiments. As shown in <FIG>, some of these end components <NUM> are puckered radially outward and some end components <NUM> are puckered radially inward - this can be done during the shape setting process by mechanically grasping these end components <NUM> with a gripping tool (e.g., pliers) and bending some radially inward and some radially outward. This is shown best in <FIG>, where end components 122a-122b are puckered radially outwardly and end components 122c-122d are puckered radially inwardly.

One advantage in placing some of these end components radially inwardly is that there is a natural constriction along the distal end of the device <NUM> to help trap or retain clot/thrombus within the device <NUM>. In other words, there is no complete opening along the distal end of the device. Various combinations of the end components can be placed radially inwardly or radially outwardly to affect the distal end profile (e.g., more radially inward end components would create more of a closed distal end shape). Additionally, rather than being puckered radially outwardly or radially inwardly, one or more end components can simply adopt a normal tubular configuration since that they are substantially flush with the outer portion of the tubular thrombectomy device <NUM> and in this way occupy a substantially flat plane. One advantage of this design is that the device can be customized to any situation by controlling the amount of end components which are inwardly oriented to create the distal constriction to help retain thrombus.

Some embodiments described herein have disclosed the use of a radiopaque element (e.g., the radiopaque coil or spring <NUM> of <FIG>) to aid in visualizing a clot retrieval device. The following embodiments offer other approaches of augmenting radiopacity along a clot retrieval device. These embodiments can also be combined with the radiopaque coil/spring concept shown in <FIG> and described earlier, to further augment radiopacity, or can be used as a stand-alone concept without such inclusion of the radiopaque coil/spring concept detailed earlier.

<FIG> shows a thrombectomy device <NUM>, according to one embodiment, which includes a plurality of struts <NUM> - including one or more longer configured struts <NUM> along the length of the device <NUM> and one or more shorter configured struts <NUM>. The thrombectomy device <NUM> can be configured to be more elongated in shape (e.g., closer to what is shown in <FIG>), and can use various strut shape configurations. These longer configured struts <NUM> represent good locations where radiopacity of the device can be enhanced, since the struts <NUM> occupy a substantial length of the device <NUM>.

<FIG> illustrates a radiopaque element <NUM> which can be added to one or more struts <NUM> along one or more locations of each strut. In one example, the radiopaque element is a coil or spring which is placed over one or more regions of the struts <NUM>. In one example, the radiopaque coil or spring is formed by winding a wire around the region to create a plurality of windings (e.g., two or more windings) to create the coil or spring shape - in one example, <NUM>-<NUM> windings are used. Any radiopaque metallic material (e.g., tantalum, platinum, palladium, gold, tungsten, or drawn-filled tubing with a radiopaque core and nitinol jacket) can be used to create the radiopaque element. In one example, the radiopaque element <NUM> can be placed at least along the proximal and distal end regions of struts <NUM> so these end regions have augmented visualization.

In one embodiment, the radiopaque element <NUM> is a spiral cut tube. The spiral cut tube can be created by taking a tubular element and creating a spiral cut pattern along the length of the tube, to create a plurality of nested spiral elements. With a spiral cut tube, the windings will be thicker than a coil or spring and be sized such that the thicker windings are substantially flush with each other (e.g., to give the appearance of a tube). The spiral cut tubing concept could also be used on the embodiments described earlier in regard to <FIG>, where a spiral cut tube can be used instead of a coil or spring member <NUM>.

<FIG> illustrates another embodiment, which utilizes a radiopaque plating element <NUM>, instead of a coil or spiral cut tube. The plating element <NUM> has a cut-out region <NUM>. This cut out region <NUM> helps define a projecting surface <NUM> (e.g., the portion of the plating element <NUM> which is not cut out or removed) which is configured such that a projecting surface <NUM> extends over the strut component <NUM> while the rest of the plating element extends under the strut component <NUM>. In this way, the strut is placed between or sandwiched between two parts of plating element <NUM>. The plating element is welded at location <NUM> along the projecting surface <NUM> to affix the plating surface to the strut.

<FIG> illustrates a similar plating concept but utilizes an alternative configuration utilizing two projecting surfaces <NUM>, <NUM> and two attachment locations <NUM>, <NUM> - instead of just one.

One advantage to the use of plating element <NUM> is that it can be easily assembled onto the thrombectomy device after formation and assembly of the thrombectomy device, since it is configured as a plate which is simply added to the strut. The plating element <NUM> can be configured in a variety of lengths and can be placed along one or more locations along strut component <NUM>.

In another embodiment, a radiopaque tubular element (which can be referred to as a marker band) can be placed over strut regions <NUM> at one or more locations along the one or more elongated strut regions <NUM>.

In another embodiment, shown in <FIG>, a strut region <NUM> includes one or more coining holes or slots <NUM>. The coining holes or slots are empty spaces created along the strut region and can be made, for instance, by utilizing a hole making apparatus such as a puncturing needle or drill along selective portions of a strut region <NUM>. In one embodiment, the hole or slot <NUM> is positioned completely through the width of the strut so as to form a complete hole which the radiopaque composition then fills. In another embodiment, the hole or slot <NUM> is only partial such that it takes the form of a superficial recess along a width of the strut but does not extend completely through the strut. The coining hole or slot <NUM> is then filled with a metallic radiopaque composition (e.g., tantalum, platinum, palladium, or gold). In one example, a metallic radiopaque material machined to a similar size as the coining hole so as to fit snugly within said coining hole and then placed in the hole where adhesive, welding, or other mechanical techniques can be then used to affix it. In another example, the metallic radiopaque material is melted to a liquid or gel-like state, poured or otherwise placed within the slot/hole <NUM>, and is then left to solidify. The coining holes/slots <NUM> can be placed in one or more regions along a lengthier strut region <NUM> of the thrombectomy device, or can be placed along any strut element <NUM> of the device including the shorter strut regions <NUM>. One advantage to this technique is that the overall thickness of the device will not be as affected since there is nothing being added to or physically over a strut region to enhance radiopacity.

Claim 1:
A clot retrieval device (<NUM>) comprising:
a device body comprising a plurality of struts (<NUM>) and having a medial section (<NUM>) and tapered proximal (108a) and distal (108b) ends, the device body adopting an elongated configuration when in a delivery catheter and a radially expanded configuration when outside of the delivery catheter; and
a coil (<NUM>) positioned within the device body near or adjacent at least some of the plurality of struts, wherein when adopting the radially expanded configuration, the coil applies an outward force against the plurality of struts via an inherent tension that biases the coil towards radial expansion.