Patent Description:
Thrombectomy devices made up of an elongate catheter attached to a handle in which the elongate catheter has a distal part and a proximal part with a thrombus capture body in the form of a radially expansible member such as a cage disposed on the distal part of the catheter which is radially expansible between a contracted orientation and an expanded, thrombus-capture, orientation are widely used in human and animal medicine. Typically, the radially expansible member has an open end for receipt of thrombus and the device is provided with control arms to move the thrombus capture body between the contracted and expanded orientations.

Some thrombectomy devices are also provided with extraction mechanisms located in or adjacent to the radially expansible member that serve to extract captured thrombus from the thrombectomy device.

However, known thrombectomy devices can suffer from a number of disadvantages. As the radially expansible member must be moved between the contracted and expanded orientations, the relative positions of elements of the thrombectomy device can shift, e.g. in an axial direction along the catheter, into positions that are sub-optimal in use. For example, undesired movement of the extraction mechanism or the opening into the extraction mechanism can severely compromise extraction performance. More generally, uncontrolled positional shifts of elements within the thrombectomy device can reduce the efficacy of the devices.

In addition, regardless of the problems associated with uncontrolled relative movement of elements of the device outlined above, the radially expansible members and extraction mechanisms employed in the thrombectomy devices of the prior art can sometimes fail to capture and extract thrombus as efficiently as possible. <CIT>, <CIT> and <CIT> disclose thrombectomy devices of the prior art.

An object of the invention is to overcome at least some of the problems of the prior art.

According to the invention there is provided a thrombectomy device for removing matter from a body lumen as claimed in claim <NUM>.

In any embodiment, the extraction mechanism and the distal control arm are configured to be coupled at the handle to effect the synchronised axial movement.

The extraction mechanism comprises a helical coil.

In a preferred embodiment, the thrombectomy device comprises at least one extraction window on the distal control arm wherein the extraction window is positionally axially fixed with respect to the helical coil and, optionally, the extraction window has a longitudinal and circumferential axis along the distal control arm. Preferably, in any embodiment, the helical coil comprises a shorter pitch at or adjacent the extraction window and a longer pitch towards the handle.

Alternatively or in addition, the helical coil comprises a distal small diameter coil portion at or adjacent the extraction window and a proximal large diameter coil portion contiguous with the small diameter coil portion towards the handle.

Optionally, in any embodiment, the helical coil has a variable thickness or cross-sectional area.

The extraction mechanism further comprises a coil rotation mechanism in or adjacent to the handle. In any embodiment, the coil rotation mechanism comprises a drive train slidably connected to the helical coil to facilitate axial translation of the helical coil.

In any embodiment, the helical coil and the distal control arm are coupled at a biasing mechanism in the handle. Preferably, the biasing mechanism biases the extraction mechanism proximally and/or distally relative to the proximal arm.

Optionally, in any embodiment, the thrombectomy device further comprises a manually operable over-ride mechanism to over-ride the biasing mechanism.

In one embodiment, the thrombectomy device further comprises a guide wire lumen through the catheter member. Preferably, the helical coil is positioned over the guide wire lumen and the guidewire lumen is not rotationally coupled to the helical coil.

Optionally, in any embodiment, the thrombectomy device further comprises an extraction port in fluid communication with the extraction mechanism for extracting thrombus from the extraction mechanism.

In any embodiment, the helical coil is connected to the distal control arm at one end thereof.

In any embodiment, the guidewire lumen is axially moveable relative to the distal control arm.

Optionally, in any embodiment, the coil rotation mechanism is axially fixed to the distal control arm. Alternatively, the coil rotation mechanism is fixedly attached to the handle.

The disclosure also extends to a thrombectomy device further comprising an operative connection between the helical coil and the coil rotation mechanism.

In any embodiment, device elements can be configured to be rotatable if desired. In one embodiment, the device is configured to facilitate rotation of the expansible member and the distal/proximal control arms to aid in separating thrombus from vessel walls.

Additional guides <NUM> can facilitate the rotation movement thereby providing a mechanism for components to slide and rotate as required.

In any embodiment, the radially expansible member is provided with one or more radially expansible member blockers to prevent radially expansible member inversion in use. Suitably, the blockers are a pair of oppositely disposed spaced blockers.

The disclosure also extends to a thrombectomy device for removing matter from a body lumen comprising:.

Preferably, the extraction mechanism and the distal control arm are coupled to enjoy a synchronised axial movement so that the extraction mechanism is positionally axially fixed with respect to the distal control arm.

In another embodiment, the disclosure extends to a thrombectomy device for removing matter from a body lumen comprising:.

Optionally, the outer sheath is axially slidably moveable to expose and cover the expansible member in use as required.

In one embodiment, the device is provided with guides to facilitate the axial movement of the sheath.

In one embodiment, the extraction mechanism comprises an extraction lumen made up of a relatively smaller diameter extractor lumen portion and a relatively larger diameter lumen portion.

Optionally, the small diameter coil portion may be the same as the large diameter coil portion within the small and large diameter lumen portions.

In any embodiment of the invention described herein, the shorter pitch can transition to the longer pitch at a pitch transition zone. Preferably the pitch transition zone starts within a distance defined by approximately <NUM> times the pitch distal to the proximal end of an extraction window <NUM> to minimise the distance material travels at the short pitch and reduce the potential for the extraction mechanism to block in use. In one embodiment, the length of the transition zone is preferably less than a distance defined by <NUM> times the distal pitch.

In any embodiment of the invention, the helical coil comprises an elongate wire having a variable thickness or cross-sectional area.

In any embodiment the helical coil may comprise coiled wire(s) or cut tube profiles with different cross sectional profiles, including round, ovoid, square, rectangular, triangular or other profiles suitable for cutting and extraction when rotated.

Preferably, the extraction window is located or positioned within the radially expansible member. More preferably, the extraction window is located towards a distal end of the radially expansible member. Alternatively or in addition, the extraction window is located proximal to and outside the radially expansible member.

In one embodiment, the extraction window has both a longitudinal and circumferential axis along the distal control arm.

Optionally, the radially expansible member is formed from braided or twisted material such as wires. Alternatively or in addition, the radially expansible member is formed from a cut or formed profile to form the distal, central flexible and proximal zones.

By coupling and synchronising axial movement of the helical coil and the distal control arm it is ensured that the relative positions of the extraction mechanism and the distal control arm are maintained in use. More particularly, the relative positions of the extraction window in the distal control arm and the extraction mechanism such as the helical coil are maintained to ensure optimal extraction. Importantly, the relative positioning of the transition zone in helical coils having a variable pitch to the extraction zone is maintained to ensure optimal extraction. In short, in use, as the extraction mechanism is disposed within the distal control arm and can be moved in concert with the radially expansible member as the radially expansible member is moved between the expanded and contracted positions, the position of the extraction mechanism, and in particular the position of the shorter pitch in an extraction mechanism made up of the helical coil having a variable pitch, relative to the extraction window is maintained. Other benefits of the thrombectomy devices of the invention are outlined further below.

<FIG> show a first embodiment of a thrombectomy device <NUM> of the invention made up of a controllable catheter member <NUM> having a handle <NUM> at a proximal end thereof and a compliant basket- or cage-like radially expansible member <NUM> for receiving thrombus at a distal end thereof. The controllable catheter member <NUM> is made up of an annular distal control arm <NUM> and an annular proximal control arm <NUM> partially surrounding and overlapping the distal control arm <NUM> with the radially expansible member <NUM> being attached to the distal control arm <NUM> at a distal end <NUM> of the radially expansible member <NUM> and to the proximal control arm <NUM> at a proximal end <NUM> of the radially expansible member <NUM>. More particularly, the radially expansible member <NUM> is attached to the distal control arm <NUM> at its distal end <NUM> and to the proximal arm <NUM> at its proximal end <NUM> at respective operative connections <NUM>,<NUM> and the proximal control arm <NUM> is fixedly attached to the handle <NUM> at fixed connections <NUM> so that relative axial movement of the distal and proximal control arms <NUM>,<NUM> effects expansion and contraction of the radially expansible member <NUM> i.e. the proximal control arm <NUM> is operatively connected to the radially expansible member <NUM> and the distal control arm <NUM> is operatively connected to the radially expansible member <NUM> distally of the proximal control arm <NUM> connection.

Relative movement of the distal and proximal control arms <NUM>,<NUM>, and in particular axial movement of the distal control arm <NUM> is effected by an operating mechanism <NUM> contained within the handle <NUM> so that the diameter/radial strength of the radially expansible member <NUM> can be adjusted in use.

The distal control arm <NUM> has an elongate tubular outer wall <NUM> extending from inside the handle <NUM> to the radially expansible member <NUM>. Within the handle <NUM>, the tubular outer wall <NUM> is attached to a distal control arm housing <NUM> contained within the handle <NUM>.

The annular distal control arm <NUM>, and more particularly the tubular outer wall <NUM>, defines an elongate extraction lumen <NUM> extending between the housing <NUM> and the distal end of the distal control arm <NUM> for containing a thrombus extraction mechanism <NUM> which in the present embodiment includes a helical coil <NUM>. As shown particularly in <FIG> described in more detail below, the helical coil <NUM> can have a variable pitch in which a short pitch <NUM> transitions to a longer pitch <NUM> at a transition zone <NUM> between the short and long pitches. The extraction mechanism <NUM> further includes a coil rotation mechanism <NUM> contained within the handle <NUM> and, more particularly, within the housing <NUM> attached to the distal control arm <NUM> in the handle <NUM>. The helical coil <NUM> of the extraction mechanism <NUM> is actuated, i.e. rotated, by the coil rotation mechanism <NUM>.

As the distal control arm <NUM> and the extraction mechanism <NUM> are combined in a single structure, the thrombectomy device <NUM> profile is reduced/minimised. This minimised or reduced profile allows the device <NUM> to gain access to areas within a confined anatomy.

The tubular outer wall <NUM> of the distal control arm <NUM> is provided with at least one elongate extraction window <NUM> through which the extraction mechanism <NUM> can make contact with a thrombus. Accordingly, collected material can enter the extraction lumen <NUM> from inside or proximal to the radially expansible member <NUM>. As will be appreciated by those skilled in the art, the tubular outer wall <NUM> can have more than one extraction window <NUM>. In addition, the extraction window <NUM> can be an axial extraction window <NUM> on the tubular outer wall <NUM> or an end extraction window <NUM> located at the distal end of the distal control arm <NUM>. In the present embodiment, the extraction window <NUM> is located on the tubular control arm <NUM> within the radially expansible member <NUM> and the helical coil <NUM> is axially adjacent to the extraction window <NUM> in the extraction lumen <NUM> so that material that enters the extraction window <NUM> into the extraction lumen <NUM> is positively displaced and transported along the extraction lumen <NUM> ensuring the extraction mechanism <NUM> does not get blocked.

Importantly, the thrombectomy device <NUM> is configured so that the extraction mechanism <NUM> and the distal control arm <NUM> are coupled to enjoy a synchronised axial movement. More particularly, the extraction mechanism <NUM> and the distal control arm <NUM> are configured to be coupled at the handle <NUM> to effect the synchronised axial movement. Accordingly, in the present embodiment, the helical coil <NUM> is connected to the tubular wall <NUM> of the distal control arm <NUM> at an axial connection <NUM> within the handle <NUM> so that the helical coil <NUM> is positionally axially fixed with respect to the distal control arm <NUM>/extraction lumen <NUM> whilst being rotatable within the extraction lumen <NUM>. More particularly, the helical coil <NUM> is axially fixed (i.e. axially and rotationally positionally fixed) with an axial connection <NUM> at only one end (in the present embodiment adjacent the housing <NUM>) so that there is no tension on the helical coil <NUM> allowing easier rotation during operation and bending/flexing of the thrombectomy device <NUM>. In general, the internal helical coil <NUM> is axially fixed with respect to the extraction lumen <NUM> at a minimum of one point.

As indicated above, the thrombectomy device <NUM> is provided with the coil rotation mechanism <NUM> within the housing <NUM> in the handle <NUM> to effect rotation of the helical coil <NUM>. In the present embodiment, the coil rotation mechanism <NUM> is configured to translate axially within the housing <NUM> in synchronicity with the distal control arm <NUM> - the rotation mechanism <NUM> within the housing <NUM> being axially fixed to the distal control arm <NUM> containing the extraction mechanism <NUM> whilst being axially moveable with respect to the handle <NUM>. Accordingly, a drive train <NUM> between the rotation mechanism <NUM> and the helical coil <NUM> does not have to provide for axial movement of the helical coil <NUM> relative to the rotation mechanism <NUM> to maintain synchronicity.

Accordingly, axial movement of the extraction mechanism <NUM> i.e. the helical coil <NUM>, the rotation mechanism <NUM> and the distal control arm <NUM> is synchronised during movement of the radially expansible member <NUM> between the contracted position and expanded positions to ensure that relative positioning of the transition zone <NUM> of the helical coil <NUM> to the extraction window <NUM> is maintained in use so that the extraction mechanism <NUM> operates effectively.

In a further embodiment of the invention, the extraction mechanism <NUM> can include an aspiration mechanism to further assist in transporting thrombus material through the extraction lumen <NUM> and to prevent blockage of the extraction lumen <NUM>.

<FIG> show a second embodiment of a thrombectomy device <NUM> of the invention broadly similar to thrombectomy device <NUM> of <FIG> but in which the thrombectomy device <NUM> is provided with an axially moveable guidewire lumen <NUM> for receiving a guidewire in use. Like numerals indicate like parts.

As shown in the drawings, the elongate guidewire lumen <NUM> extends centrally through the distal control arm <NUM> and is defined by an elongate tubular guidewire lumen wall <NUM> formed in the distal control arm <NUM> with the helical coil <NUM> of the extraction mechanism <NUM> positioned over the guidewire lumen wall <NUM>. At its proximal end, the guidewire lumen <NUM> extends from the housing <NUM> within the handle <NUM> and exits the handle <NUM> at a guidewire lumen opening <NUM> to receive a guidewire in use.

The guidewire lumen <NUM>, and more particularly the guidewire lumen wall <NUM>, is fixedly connected at only one end thereof e.g. at the distal end of the radially expansible member or at the proximal end of the handle <NUM> so that compression of the guidewire lumen <NUM> and the helical coil <NUM> is prevented during bending of the thrombectomy device <NUM> (e.g. where the guidewire lumen wall <NUM> is fixed at both ends). Accordingly, in the present embodiment, the guidewire lumen wall <NUM> is fixed to the distal end <NUM> of the radially expansible member <NUM> and the helical coil <NUM> is axially fixed with respect to the extractor lumen <NUM> as previously described.

The use of a guidewire with the thrombectomy device <NUM> of the invention ensures the device can gain access to tortuous anatomy as it can be advanced over the guidewire.

Accordingly, in the present embodiment, the guidewire lumen <NUM> is axially moveable relative to the distal control arm <NUM> in the direction indicated by the arrows, at least on one end, so that axial freedom of movement to the guide wire lumen <NUM> is provided also allowing the device <NUM> to navigate through tortuous anatomy.

The guide wire lumen <NUM> cannot rotate relative to the distal control arm <NUM> while the helical coil <NUM> rotates over the guide wire lumen <NUM> and the extraction lumen <NUM> remains stationary as described in <FIG> - i.e. the guidewire lumen <NUM> is not rotationally coupled to the helical coil <NUM>. Accordingly, the extraction mechanism <NUM>, i.e. the helical coil <NUM>, achieves more effective friction between the guidewire lumen wall <NUM> of the guide wire lumen <NUM> and the material being transported to aid in ensuring the material does not rotate with the helical coil <NUM> and instead is transported axially. In addition, the non-rotating guide wire lumen <NUM> prevents the guide wire (inside it) from rotating.

<FIG> shows a thrombectomy device <NUM> of the invention similar to the devices previously described having a variant of the synchronised coil rotation mechanism <NUM> in which the rotation mechanism <NUM> is fixedly attached to the handle <NUM> of the device <NUM>. Like numerals indicate like parts.

As shown in the drawing, the housing <NUM> is omitted from the distal control arm <NUM> and the coil rotation mechanism <NUM> is fixedly attached to an internal face of the handle <NUM>. Accordingly, in the present embodiment, the coil rotation mechanism <NUM>, and in particular the drive train <NUM> of the coil rotation mechanism <NUM> is slidably operatively connected to the helical coil <NUM>, via an operative connection <NUM> between the rotation mechanism <NUM> and the helical coil <NUM> to facilitate axial translation of the helical coil <NUM> while maintaining a rotational connection.

Accordingly, the rotation mechanism <NUM> is fixedly connected to the handle <NUM>/ proximal arm <NUM> and is operatively connected to the coil <NUM> thus allowing axial movement of the extraction mechanism <NUM> relative to the rotation mechanism <NUM>. As a result, the drive train <NUM> between the rotation mechanism <NUM> and the helical coil <NUM> facilitates axial translation of the helical coil <NUM> relative to the rotation mechanism <NUM> reducing the space requirement within the handle <NUM> and reducing the mass of the extraction mechanism <NUM> that translates axially.

<FIG> shows a further embodiment of the invention, similar to the embodiments previously described in which the thrombectomy device <NUM> is configured so that the extraction mechanism <NUM> in the form of the helical coil <NUM> and the distal control arm <NUM> are coupled at the handle <NUM> to effect the synchronised axial movement and like numerals indicate like parts. However, in the present embodiment, the extraction mechanism <NUM> and the distal control arm <NUM> are configured to be coupled at a biasing mechanism <NUM> in the handle <NUM> to bias the distal arm <NUM> relative to the handle <NUM>/proximal arm <NUM>.

Similarly, in the embodiment described in <FIG>, the biasing mechanism <NUM> could be coupled directly or indirectly to the distal arm <NUM> relative to provide the bias with respect to the handle <NUM>/proximal arm <NUM>.

Like numerals indicate like parts. As shown in the drawing, in the present embodiment, the biasing mechanism <NUM> is disposed between the housing <NUM> of the distal arm <NUM> and the handle <NUM> to bias the extraction mechanism <NUM> of the distal arm <NUM> proximally or distally relative to the handle <NUM>/proximal arm <NUM>. Accordingly, an axial biasing force is provided to the radially expansible member <NUM> biasing it into an expanded position as required.

In one embodiment, the biasing mechanism <NUM> delivers a substantially constant force to assist in controlling the outward radial force of the radially expansible member <NUM>.

As shown in the drawing, the biasing mechanism <NUM> can be a spring <NUM> such as a constant force spring <NUM>.

As previously described, synchronized axial movement of the helical coil <NUM> and the distal control arm <NUM> during movement of the radially expansible member <NUM> between the contracted position and expanded positions ensures the relative positioning of the transition zone <NUM> of the helical coil <NUM> to the extraction window <NUM> is maintained thus ensuring the extraction mechanism <NUM> operates effectively.

<FIG> shows a side elevation of a further embodiment of the invention similar to the devices previously described but in which the device <NUM> is provided with a manually operable over-ride mechanism <NUM> to over-ride the biasing mechanism <NUM>. The over-ride mechanism <NUM> extends from the handle housing <NUM> and is manually operable by a user.

The over-ride mechanism <NUM> is configured to exert an axial force on the distal control arm <NUM> which contains the extraction mechanism <NUM> in an opposite direction to the force applied to the distal control arm <NUM> by the biasing mechanism <NUM> to allow a user to collapse the radially expansible member <NUM> when required. In the present embodiment, the over-ride mechanism <NUM> extends outwards from the distal control arm housing <NUM> contained within the handle <NUM> and through the handle housing <NUM> for manual activation by a user. The over-ride mechanism <NUM> can be in the form of a cam, a linear actuator, an electrically driven device or the like.

In a further embodiment of the invention, the biasing mechanism <NUM> can include defined axial travel limiting stops <NUM> to limit travel and prevent axial over-travel of the distal control arm <NUM> to ensure that the radially expansible member <NUM> is not stretched beyond its operating range. As shown in the drawing, in the present embodiment, the travel limiting stops <NUM> are disposed either side of and spaced apart from the biased distal control arm housing <NUM> to limit travel of the distal control arm housing <NUM> and hence the extraction mechanism <NUM>. The travel limiting stops <NUM> can be in the form of spaced apart fingers <NUM> extending inwards from the handle housing <NUM>.

Furthermore, as shown in the <FIG>, in a further embodiment of the invention, the radially expansible member <NUM> can be provided with one or more radially expansible member or basket blockers <NUM> to prevent radially expansible member inversion in use.

In the present embodiment, the blockers <NUM> are a pair of oppositely disposed spaced blockers <NUM> disposed adjacent the operative connections <NUM>,<NUM>. The blockers <NUM> can be mounted on the tubular wall <NUM> of the distal control arm <NUM>.

<FIG> and <FIG> show a side elevation of a further embodiment of the invention similar to the embodiments previously described in which the device <NUM> is provided with a tubular extraction port <NUM> extending laterally outwards from the handle <NUM> for extracting thrombus from the extraction mechanism <NUM>. Like numerals indicate like parts.

As shown in the drawings, generally, the laterally extending extraction port <NUM> extends outwards from the tubular wall <NUM> of the distal control arm <NUM>, and optionally the handle <NUM>, adjacent to or proximal of the proximal end of the helical coil <NUM> at the handle <NUM> so that the extraction port <NUM> is in fluid communication with the extraction lumen <NUM>. The extraction port <NUM> can be integral with the extraction mechanism <NUM> or, as shown in the drawing, can be configured to be part of an extraction port insert <NUM> inserted in and contiguous with the distal arm <NUM> and the extraction mechanism <NUM>. In this format, the insert <NUM> has a cylindrical wall <NUM> sized and shaped to engage with the distal control arm <NUM> defining a helical coil <NUM> receiving bore <NUM> contiguous with the extraction lumen <NUM> to receive material from the helical coil <NUM>. The insert <NUM> is further provided with an elongate cylindrical member <NUM> inserted in the helical coil <NUM> and a terminal seal <NUM> to prevent leakage from the insert <NUM>.

The extraction port <NUM> facilitates material (thrombus) to be removed from the extraction mechanism <NUM> to a location outside the handle <NUM> through a handle opening <NUM> in the handle housing <NUM> without leakage of thrombus inside the device <NUM> while still facilitating rotation of the helical coil <NUM>. The central longitudinal axis of the outwardly extending extraction port <NUM> is oriented at an angle of <NUM>-<NUM> degrees to the central axis of the helical coil <NUM> to optimise the efficacy of thrombus exiting from the extraction mechanism <NUM>.

As shown in the drawings, the proximal end of the helical coil <NUM> is attached to the cylindrical member <NUM> and the cylindrical member <NUM> is at least partially contained within the extraction port <NUM> so that it is possible to seal around the cylindrical member <NUM> which, being attached to the helical coil <NUM>, can form part of the coil rotating mechanism <NUM> to rotate the helical coil <NUM>.

The seal <NUM> is located adjacent to the extraction port <NUM> and the cylindrical member <NUM> as this is the location where leakage is likely to occur.

In one embodiment, the cylindrical member <NUM> has a cylindrical member lumen for receiving a guide wire lumen <NUM> and is rotatable about the guide wire lumen <NUM> to enable the use of a guide wire with the device <NUM>. In another embodiment, an additional sealing member can form a seal between the rotatable cylindrical member lumen and the guide wire lumen <NUM> to prevent leakage.

<FIG> shows a side elevation of a further embodiment of the invention similar to the device shown in <FIG> in which catheter elements such as the extraction mechanism <NUM> of the device in the handle <NUM> can be translated axially as previously described. Like numerals indicate like parts. However, in the present embodiment, the device <NUM> is provided with an outer sheath to prevent blood vessel trauma and, optionally, some catheter elements of the device <NUM> can be configured to rotate.

More particularly, as shown in the drawing, the device <NUM> is also provided with an outer sheath <NUM> to prevent blood vessel trauma in use. The outer sheath <NUM> extends over the exposed portion of the proximal control arm <NUM> to prevent the device <NUM> from causing vessel trauma when navigating to a treatment zone. Additionally, the outer sheath <NUM> can be axially slidably moveable as indicated by the arrows to expose and cover the expansible member <NUM> in use as required.

As shown in the drawing, in this embodiment, the handle housing <NUM> can be provided with guides <NUM> adjacent the proximal arm <NUM> to facilitate the axial movement of the sheath <NUM>.

Optionally, in a further embodiment which may or may not include a sheath <NUM> as outlined above, some device elements can be configured to be rotatable if desired. In one embodiment, the device <NUM> is configured to facilitate rotation of the expansible member <NUM> and the distal/proximal control arms <NUM>,<NUM> to aid in separating thrombus from vessel walls.

As will be appreciated by those skilled in the art, if required, the guides <NUM> in the handle housing <NUM> can be configured to facilitate axial only movement of the extraction mechanism <NUM> within the distal control arm <NUM>. Accordingly, the extraction mechanism <NUM>/distal control arm <NUM> can translate axially to expand and collapse the radially expansible member <NUM> whilst ensuring there is no rotation of the distal control arm <NUM> relative to the proximal control arm <NUM> and thereby also ensuring there is no twist introduced to the radially expansible member <NUM> in use.

As described above, the extraction mechanism <NUM> can also be biased in a specific axial direction (either proximal or distal) by the biasing mechanism <NUM> to provide an axial force to the radially expansible member <NUM> e.g. biasing it into an expanded position.

<FIG> show helical coil <NUM> configurations suitable for use in thrombectomy devices <NUM>.

As shown in <FIG>, the helical coil <NUM> of the extraction mechanism <NUM> can have a variable pitch e.g. a relatively shorter pitch (the short pitch) <NUM> towards or at the distal end, i.e. at or adjacent the extraction window <NUM> and a relatively longer pitch (the long pitch) <NUM> proximally of the short pitch <NUM>.

The variable pitch provides relief/space/freedom to the materials being extracted, allowing it to be transported easier through the extraction lumen. More particularly, a short pitch <NUM> at the extraction window <NUM> ensures that an increased number of extraction "bites" are taken from thrombus material per rotation by the helical coil <NUM> relative to the extraction window <NUM>, to efficiently collect thrombus and convey the thrombus into the extraction mechanism <NUM> within the distal control arm <NUM> whilst also allowing more time for a thrombus to enter the extraction lumen <NUM>. The received material is then conveyed by the helical coil <NUM> to the longer or increased pitch <NUM> of the helical coil <NUM> so that it is no longer tightly packed between the loops of the helical coil <NUM>. Blockages of the extraction mechanism <NUM> are therefore prevented. In addition, the longer pitch <NUM> increases the extraction rate (i.e. axial movement of material) of the extraction mechanism <NUM>.

In one embodiment, the distal portion of the helical coil <NUM> has a pitch proportional to the rotational speed and the diameter of the helical coil to allow for more effective/efficient transport of the material.

In another embodiment, the proximal portion of the helical coil (the longer pitch <NUM>) has a pitch of <NUM>-<NUM> times the distal pitch (the shorter pitch <NUM> ). The Applicant has found that this pitch relationship between the shorter and longer pitch helps to ensure that the extraction mechanism <NUM> does not block in use.

As indicated above, typically the extraction window <NUM> is located axially adjacent to the shorter pitch <NUM> at the distal end to ensure that material entering the extraction lumen <NUM> is easier to transport. In one embodiment, the shorter pitch <NUM> starts to transition to a longer pitch <NUM> close to the proximal end of the extraction window <NUM> to minimise the distance the material travels while in the short pitch <NUM> and hence also reduce the potential for the extraction mechanism to get blocked.

The shorter pitch <NUM> can therefore transition to the longer pitch <NUM> at a pitch transition zone <NUM> which preferably starts within a distance defined by approximately <NUM> times the pitch distal to the proximal end of the extraction window <NUM> which also minimises the distance the material travels at the short pitch <NUM> and hence reduces the potential for the extraction mechanism <NUM> to block in use. This also speeds up the overall extraction time of a captured thrombus. The length of the transition zone <NUM> is preferably less than a distance defined by <NUM> times the distal pitch, and is positioned proximal of the proximal end of the extraction window <NUM> which serves to minimise the distance extracted material travels at the shorter pitch at the extraction window <NUM> and hence further reduces the potential for the mechanism to get blocked during use.

<FIG> shows an enlarged cross-sectional side view of a helical coil <NUM> of an extraction mechanism <NUM> in which the helical coil <NUM> is made up of a (distal) small diameter coil portion <NUM> at or adjacent the extraction window <NUM> and a (proximal) large diameter coil portion <NUM> contiguous with the small diameter coil portion <NUM> disposed towards the handle <NUM>. More particularly, as shown in the drawing, the extraction lumen <NUM> is made up of a distal relatively smaller diameter extractor lumen portion <NUM> (the small diameter lumen) at the extraction window <NUM> and a proximal relatively larger diameter lumen portion <NUM> (the large diameter lumen) i.e. the inner diameter of the extraction lumen <NUM> increases proximal to the extraction window <NUM>. In the present embodiment, the transition zone <NUM> is defined between the small and large diameter lumens <NUM>,<NUM>. Optionally, the small diameter coil may be the same as the large diameter coil within the small and large diameter lumen.

The large diameter lumen <NUM> provides relief/space/freedom to extracted material allowing it to be transported easier through the extraction lumen <NUM>.

As indicated above, the diameter of the diameter of the helical coil <NUM> preferably increases at the large diameter coil portion <NUM> adjacent to the large diameter lumen <NUM>. This prevents extracted material from flowing uncontrollably between the outer diameter or edge of the helical coil <NUM> and the internal diameter or edge of the extraction lumen <NUM>.

<FIG> shows an enlarged cross-sectional side view of an alternative helical coil <NUM> in which the elongate wire of the helical coil <NUM> has a variable thickness or cross-sectional area. More particularly, the elongate wire of the helical coil <NUM> has a relatively larger cross-sectional area portion <NUM> (the large cross-sectional area portion) and a relatively smaller cross-sectional area portion <NUM> (the small cross-sectional area portion). The small cross-sectional area portion <NUM> is disposed towards the proximal end of the extraction lumen while large cross-sectional area portion is disposed towards the distal end at the extraction window <NUM> i.e. the cross-sectional area of the helical coil wire reduces proximal to the proximal end of the extraction tube window <NUM> to provide space/relief to the material being transported through the extraction lumen <NUM> preventing it from getting blocked.

<FIG> show various optional configurations of the extraction window <NUM> on the distal control arm <NUM>. Like numerals indicate like parts. Generally, the extraction window can be positioned within and/or proximal and/or distal to the radially expansible member <NUM> and is made up of an elongate axial window <NUM> defined in the tubular wall <NUM> of the distal control arm <NUM> to provide access to the helical coil <NUM> of the extraction mechanism <NUM> in the extraction lumen <NUM>.

In the embodiment shown in <FIG>, the extraction window <NUM> located or positioned within the radially expansible member <NUM> on the distal control arm <NUM>. The extraction window <NUM> is located towards the distal end <NUM> of the radially expansible member <NUM> Accordingly, the extraction window <NUM> effectively removes material from inside the radially expansible member <NUM> which can gather at the distal end <NUM> of the radially expansible member <NUM>. Accordingly, in use, such an extraction window <NUM> can remove thrombus material within and proximal of the radially expansible member <NUM> and also remove any material that may be pushed proximal of the radially expansible member <NUM>.

<FIG> shows an alternative arrangement in which the extraction window <NUM> is located proximal to and outside the radially expansible member <NUM> on the distal arm <NUM> i.e. proximal of the proximal end <NUM> of the radially expansible member <NUM>. This serves to remove material proximal of the radially expansible member <NUM> which in use may be pushed proximal of the radially expansible member <NUM> and must therefore be extracted.

In one embodiment of the invention, the thrombectomy device <NUM> can further include a macerator or cutting mechanism to macerate extracted material and the extraction window <NUM> and the helical coil <NUM> can in combination co-operate to form the macerator/cutting mechanism. Accordingly, material being extracted can be macerated via a shearing action provided by the interaction between the helical coil <NUM> and the extraction window <NUM>. In all embodiments described, the helical coil may comprise of coiled wire(s) or cut tube profiles with different cross sectional profiles, including round, ovoid, square, rectangular, triangular or other profiles suitable for cutting and extraction when rotated.

<FIG> show a radially expansible member <NUM> with the elongate extraction window <NUM> located within the radially expansible member as shown in <FIG>. However, in the present embodiment, the elongate extraction window <NUM> is shaped and configured to have both a longitudinal and circumferential axis along the distal control arm <NUM> i.e. the extraction window <NUM> is disposed circumferentially about the distal control arm <NUM>. The circumferential axis increases/decreases the shearing action between the helical coil <NUM> and the extraction window <NUM> to effectively generate a scissor-like cutting action between the helical coil <NUM> and the extraction window <NUM> to provide an optimal macerating action on the material being extracted.

<FIG> show a radially expansible member <NUM> suitable for use with a thrombectomy device <NUM>.

As shown in the drawings, the radially expansible member <NUM> is in the form of a braided cage <NUM> having distinct or distinguishable distal, central flexible and proximal zones <NUM>, <NUM>, <NUM> respectively formed for example from braided or twisted material such as wires <NUM> which in turn define apertures <NUM> in the radially expansible member <NUM>. As previously described, the radially expansible member <NUM> has a distal end <NUM> in the distal zone <NUM> and a proximal end <NUM> defining a thrombus receiving opening <NUM> in the proximal zone <NUM>. The radially expansible member may also be formed from a cut or formed profile to form the desired distal, central flexible and proximal zones <NUM>, <NUM>, <NUM> respectively.

The distinct zones <NUM>, <NUM>, <NUM> within the radially expansible member <NUM> can be individually tailored to give different mechanical properties as required.

In one embodiment, the distal zone <NUM> has a reduced porosity relative to the proximal zone <NUM> i.e. the apertures <NUM> at the proximal end <NUM> are large to accept thrombus into the radially expansible member <NUM> and the apertures <NUM> at the distal end <NUM> are small to prevent thrombus from leaving the radially expansible member <NUM>. The distal end <NUM> may also be coated or attached to a permeable or impermeable membrane to further reduce or eliminate the porosity of the distal end <NUM>.

The central zone <NUM> has a circumferential edge <NUM> defining the thrombus receiving opening <NUM>. The circumferential edge <NUM> has a serrated configuration and acts as a cutting wire to separate thrombus from vessel walls. In alternative embodiments, the circumferential edge <NUM> can have a sharp or angled edge having other outline shapes as required.

In another embodiment, the central zone <NUM> is more radially compliant than the distal and proximal zones <NUM>, <NUM> respectively. Accordingly, when the radially expansible member <NUM> is expanded, the central zone <NUM> expands first so that the circumferential edge <NUM> is at (or close to) the largest diameter possible for the radially expansible member <NUM>.

<FIG> shows a plan view of a suitable braid pattern <NUM> of a portion of the radially expansible member <NUM> at the distal, central and proximal zones <NUM>, <NUM>, <NUM> respectively. As shown in the drawing, the braid pattern <NUM> is made up braided single wires <NUM> defining the apertures <NUM> in the distal zone <NUM>, twisted double wires (i.e. two twisted wires) <NUM> forming single braid wires <NUM> in the transition zone <NUM> and four twisted wires <NUM> forming single braid wires <NUM> in the proximal zone <NUM>. In other embodiments, the pattern <NUM> may be made from a cut or formed profile, where the proximal members may optionally be comprised of a larger cross sectional profile or of a different material to provide additional strength or resistance to bending during use.

In the embodiment shown in <FIG>, the radially expansible member <NUM> is made up of varying arrangements of twisted braided wires to form the proximal, central and distal zones <NUM>, <NUM>, <NUM>. Varying the wires as described above varies the properties of the radially expansible member <NUM> in the distal, central and proximal zones <NUM>, <NUM>, <NUM> so that the apertures <NUM> at the proximal end <NUM> are large to accept the thrombus into the radially expansible member <NUM> and the apertures <NUM> at the distal end <NUM> are small to prevent the thrombus from leaving the radially expansible member <NUM>. Moreover, the transition from single wires <NUM> to twisted wires <NUM>, <NUM> creates a central zone <NUM> in the structure at the circumferential edge <NUM> that is the first to expand in use and ensures the circumferential edge <NUM> is at or close to the largest outer diameter of the radially expansible member <NUM>.

Claim 1:
A thrombectomy device (<NUM>) for removing matter from a body lumen comprising:
a handle (<NUM>)
a catheter member (<NUM>) extending from the handle (<NUM>) having a a distal control arm (<NUM>) attached to a proximal housing (<NUM>) within the handle (<NUM>), and a proximal control arm (<NUM>);
a radially expansible member (<NUM>) coupled to the distal control arm (<NUM>) proximate to the distal end (<NUM>) of the radially expansible member (<NUM>) and proximate to the proximal arm (<NUM>) at a proximal end (<NUM>) of the radially expansible member (<NUM>), radially expansible between a contracted position and an expanded, thrombus-capture, position in response to axial movement of the distal control arm (<NUM>) relative to the proximal control arm (<NUM>);
a thrombus extraction mechanism (<NUM>) comprising a helical coil (<NUM>) extending through the distal control arm (<NUM>); and
a coil rotation mechanism (<NUM>) attached to the distal control arm (<NUM>) and the coil rotation mechanism (<NUM>) is in or adjacent to the handle (<NUM>);
wherein the extraction mechanism (<NUM>) and the distal control arm (<NUM>) are configured to be coupled to effect synchronised axial movement so that the extraction mechanism (<NUM>) is positionally axially fixed with respect to the distal control arm (<NUM>);
wherein the coil rotation mechanism (<NUM>) is configured to translate axially within or adjacent to the housing (<NUM>) in synchronicity with the distal control arm (<NUM>).