GB2472213A

GB2472213A - Aspiration catheter

Info

Publication number: GB2472213A
Application number: GB0913108A
Authority: GB
Inventors: Steen Aggerholm
Original assignee: William Cook Europe ApS
Current assignee: William Cook Europe ApS
Priority date: 2009-07-28
Filing date: 2009-07-28
Publication date: 2011-02-02
Anticipated expiration: 2029-07-28
Also published as: GB0913108D0; GB2472213B

Abstract

An aspiration catheter 10 has an aspiration tube 14 with a coaxial wire guide support 20. The distal end of the wire guide support 20 has a tip 18 for poking into thrombi. In use, the aspiration catheter 10 is navigated over a wire guide 40 until it is positioned adjacent to a thrombus before the tip 18 is moved back and forth in the distal-proximal direction to dislodge the thrombus and an aspiration force is applied via the aspiration tube 14 to suck the dislodged thrombus from the body.

Description

Aspiration catheter The present invention relates to a catheter for the aspiration of matter from bodily vessels or cavities. The invention has particular, although not exclusive relevance to the in-vivo aspiration of thrombi from coronary arteries.

When the endothelium of a blood vessel wall, for example a coronary artery, becomes damaged, as may occur, for example, due to trauma, smoking, old age, or obesity, atherosclerosis of that vessel may follow as lipids accumulate about the damaged area and one or more atherosclerotic plaques may form thereover. If an atherosclerotic plaque ruptures, blood may coagulate about the site of the rupture thereby forming a coronary thrombus which may partially or totally occlude the coronary artery. Partial or total occlusion of a coronary artery can result in myocardial ischeamia, either at rest or at stress, and myocardial infarction (heart attack).

The removal of thrombi from coronary arteries may be achieved by pharmacological means, for example by thrombolysis, or by mechanical means, for example by aspiration. The breaking of a thrombus into pieces during removal can be deleterious if dislodged pieces travel through the vasculature and subsequently form emboli. Accordingly, to allow aspiration of entire thrombi, aspiration catheters are configured to have an aspiration inlet that (within a specified maximum outside diameter) can pass thrombi of as large a dimension large as possible.

To allow delivery of an aspiration catheter over a wire guide, a wire guide lumen is typically provided in the aspiration catheter. The desired aim of configuring the aspiration catheter to pass thrombi of as large a dimension large as possible is then achieved by arranging the wire guide lumen at the circumference of the aspiration inlet.

According to one aspect, the present invention provides an aspiration catheter having an aspiration passageway with a distal end and a wire guide support positioned at least partially within the passageway. The wire guide support is arranged to support a wire guide so that, at least at the distal end, the aspiration passageway extends wholly around the wire guide.

By providing an aspiration passageway that extends wholly around the wire guide, it is possible to avoid aspiration dead zones. The inventor has appreciated that thrombi may migrate towards or accumulate in dead zones and thereby impede or prevent effective aspiration. A dead zone can particularly occur where the wire guide lumen lies at the circumference of the aspiration inlet, with the aspiration inlet then taking a crescent shape in the radial plane. Areas around the narrow regions of the crescent-shaped inlet can then form dead zones. By avoiding dead zones, an increase in aspiration effectiveness can be achieved which, surprisingly, outweighs the apparent disadvantage of reducing the dimension of the largest thrombus that can pass through the passageway.

In one embodiment, the aspiration catheter has a distally projecting tip for breaking up thrombi and/or for working them free from the walls of a blood vessel -this can reduce the aspiration force required to remove thrombi. Because of the more effective aspiration and the avoidance of dead zones, such mechanical breaking up of the thrombi can be undertaken without unacceptable risk of dislodged pieces travelling through the vasculature.

According to one aspect, the preset invention provides a method of aspirating matter from a body vessel. A wire guide is first navigated to a position in the vessel adjacent to the matter to be aspired before an aspiration catheter is introduced over the wire guide until it is adjacent to the matter. An aspiration force is then provided at a proximal end of an aspiration passageway of the aspiration catheter so as to effect aspiration at a distal end of the aspiration passageway in a zone that is radially circumjacent to the wire guide so as to aspire the matter into the aspiration passageway and out of the subject's body.

In one embodiment, the aspiration catheter and/or the wire guide are also moved back and forth in a proximal-distal direction so as to dislodge and/or break up the matter. This enables larger or more robust thrombi to be aspirated than if aspiration alone were to be used to dislodge and/or break up the matter.

These and various other aspects of the invention will become apparent from the following detailed description which is given by way of example only and which is described with reference to the accompanying Figures in which: Figure 1 shows a side view of an aspiration catheter; Figure 2 shows a side view of the distal end of the aspiration catheter of Figure 1; Figure 3 shows a perspective view of a portion of the aspiration catheter of Figure 1; Figure 4 shows a transverse cross-sectional view of the aspiration catheter portion of Figure 3; Figure 5 shows another transverse cross-sectional view of the aspiration catheter portion of Figure 3; Figure 6 shows a longitudinal cross-sectional view of the distal end of the aspiration catheter of Figure 1 positioned in a blood vessel longitudinally adjacent to a th rom bus; Figure 7 shows a longitudinal cross-sectional view of the distal end of the aspiration catheter of Figure 1 positioned in a blood vessel within a thrombus; Figure 8 shows a longitudinal cross-sectional view of the distal end of the aspiration catheter of Figure 1 positioned in a blood vessel longitudinally adjacent to a th rom bus; Figure 9 shows a transverse cross-sectional view of the aspiration catheter and blood vessel of Figure 6; Figure 10 shows a perspective view of a portion of an alternative embodiment of the aspiration catheter; Figure 11 shows an end view of the aspiration catheter portion of Figure 10; Figure 12 shows a perspective view of a portion of an alternative embodiment of the aspiration catheter; Figure 13 shows a longitudinal cross-sectional view of the distal end of an aspiration catheter of an alternative embodiment; and Figure 14 shows a side view of the distal end of an alternative embodiment of the aspiration catheter.

Figure 1 shows a side view of an aspiration catheter 10 having a thrombus dislodging section 12, an aspiration section 14, and a delivery and removal section 16. The thrombus dislodging section 12 comprises a tip 18 for dislodging thrombi and a wire guide support 20 for supporting a wire guide (not shown). The aspiration section 14 comprises a flexible aspiration tube 22 extending from the proximal end of the aspiration catheter 10 to the thrombus dislodging section 12, the aspiration tube 22 has a distal opening 24 for the aspiration of thrombi. The delivery and removal section 16 comprises: a flexible delivery sheath 26 having an internal diameter that is large enough for the aspiration section 14 and the thrombus dislodging section 12 to be advanced and retracted therethrough; and a fitting 28 for coupling the aspiration catheter 10 to control devices (not shown).

Figure 2 shows a side view of the distal end of the aspiration catheter 10 of Figure 1.

As can be seen, the tip 18 has a frustoconical shape with a curved distal end 31 to prevent the tip 18 from damaging vessel walls (not shown) when distally advanced thereagainst. The tip 18 also has an edge 34 at its proximal end that may be used to dislodge thrombi when the tip 18 is moved against thrombi in a proximal direction.

The tip 18 further comprises a series of longitudinally oriented and radially spaced grooves 32 (only one of which is shown in Figure 2) that increase the surface area of the tip 18 and help dislodge thrombi.

A perspective view of the aspiration tube 22 and the wire guide support 20 is shown in Figure 3 with dashed lines indicating the disposition of the wire guide support 20 within the aspiration tube 22. The wire guide support 20 comprised a flexible tube portion 20a for a wire guide (not shown) and a flexible fin portion 20b that couples the tube portion 20a of the wire guide support 20 to the aspiration tube 22 so as to keep a wire guide positioned within the tube portion 20a spaced apart from the aspiration tube 22. The distal end 20c of the fin portion 20b is proximally set back from the distal opening 24 of the aspiration tube 22. Figure 4 shows a cross-sectional view along line A-A of Figure 3 and illustrates how the fin portion 20b of the wire guide support 20 couples the tube portion 20a of the wire guide support 20 to the aspiration tube 22. As shown in Figure 5, which shows a cross sectional view along line B-B of Figure 3, the internal periphery 22a of the aspiration tube 22 at its distal opening 24 is not in contact with the wire guide support 20 sO that, in the radial plane, there is an annular passageway for aspiration between the internal periphery 22a of the aspiration tube 22 and the wire guide support 20. Accordingly, when a suction force is provided at the proximal end of the aspiration tube 22, this force is transferred to the distal end of the aspiration tube 22 so that suction is provided at the distal opening 24 of the aspiration tube 22 about the entire internal periphery 22a of the aspiration tube 22.

In operation, to access a coronary artery having a thrombus to be aspirated, a percutaneous incision is made in the patient, for example to access the femoral artery. A wire guide is then introduced via the incision into the patient's arterial system and navigated, under the guidance of an imaging system, via the aorta to the relevant coronary ostium and thence to the site of the thrombus. Suitable imaging systems include, for example, X-ray, ultrasound, magnetic resonance imaging or combinations thereof. Contrast enhancement agents may be employed in order to facilitate identification of the location of the thrombus. The aspiration catheter 10 with the thrornbus dislodging and aspiration sections 12, 14 retracted within the delivery sheath 26 is then introduced over the wire guide and navigated towards the site of the thrombus before the thrombus dislodging and aspiration sections 12,14 are advanced with respect to the delivery sheath 26 until the tip 18 of the thrombus dislodging section 12 is next (or proximally adjacent) to the thrombus.

Figure 6 shows a longitudinal cross-section of the thrombus dislodging section 12 and a portion of the aspiration section 14 positioned within a blood vessel 36 (in this case a coronary artery). As can be seen, a wire guide 40 has been navigated to abut a thrombus 38 and the tip 18 of the thrombus dislodging section 12 has been advanced along the wire guide 40 to be proximally adjacent to the thrombus 38.

Once the tip 18 of the thrombus dislodging section 12 is located as shown in Figure 6, the wire guide 40 is partially withdrawn so that its distal tip is flush with the tip 18 of the thrombus dislodging section 12 and the wire guide 40 is locked in this position with respect to the tip 18 of the thrornbus dislodging section 12 by a locking mechanism (not shown) located at the proximal end of the aspiration catheter 10.

This ensures that the distal tip of the wire guide 40 does not project from the tip 18 of the thrombus dislodging section 12 and reduces the chances of the wire guide 40 damaging or puncturing tortuous vessel walls if the tip 18 of the thrombus dislodging section 12 is directed into the thrombus 38 to dislodge it or break it up. Also, by locking the wire guide 40 sO that its distal tip is flush with the tip 18 of the thrombus dislodging section 12, the chances of thrombus particles 38a accumulating within the wire guide support's flexible tube portion 20a are reduced. If instead the wire guide was to be withdrawn within the wire guide support 20 so that its distal tip was proximally set back from the tip 18 of the thrombus dislodging section 12, then thrombus particles 38a could accumulate in the distal end of the wire guide support's tube portion 20a and subsequent retraction of the aspiration catheter 10 over the wire guide 40 would then disadvantageously release unaspirated thrombus particles back into the blood stream.

Following locking of the wire guide 40, the aspiration catheter 10 is moved back and forth in the proximal and distal directions (indicated by arrows P-D in Figures 6 to 7) so that the tip 18 of the thrombus dislodging section 12 dislodges or breaks up the thrombus 38. Figure 7 shows the tip 18 of the thrombus dislodging section 12 having been pushed into the thrombus 38 and Figure 8 shows the tip 18 of the thrombus dislodging section 12 having been proximally withdrawn from the thrombus 38 so as to dislodge particles 38a thereof.

Whilst the aspiration catheter 10 is being moved back and forth in the proximal and distal directions so as to dislodge or break up the thrombus 38, a suction force is provided at the proximal end of the aspiration tube 22. The suction force is transferred by the aspiration tube 22 so that suction is provided at its distal opening 24. As the distal end 20c of the fin portion 20b of the wire guide support 20 is proximally set back from the distal opening 24 of the aspiration tube 22, suction is provided at the distal opening 24 of the aspiration tube 22 in a zone that radially circumscribes both the tube portion 20a of the wire guide support 20 and the wire guide 40. Dislodged thrombi 38, 38a are thus sucked into the aspiration tube 22 and out of the blood vessel 36.

In Figure 9, which shows a cross-sectional view along line C-C of Figure 6, the hatched area 42 illustrates the area over which suction is provided at the distal opening 24 of the aspiration tube 22. As this suction is provided in an annular form about the wire guide support's tubular portion 20a, there are no zones around the internal periphery 22a of the aspiration tube 22 in which suction does not occur.

This removes the possibility of thrombi 38, 38a accumulating in or migrating to such zones and not therefore being aspirated into the aspiration tube 22.

A person skilled in the art will appreciate that, although the above describes the removal of a thrombus from the coronary vasculature, the apparatus could equally be employed to remove emboli or other matter. The apparatus could also be employed for the removal of matter from other parts of the body, for example from the intra-cranial arteries or pulmonary arteries and/or the branch vessels thereof. As another possibility, instead of using the apparatus in the arterial vasculature, the apparatus could be used in the venous vasculature, for example in deep veins such as the femoral or popliteal veins for the removal of deep vein thrombi.

As an alternative to the above description in which the wire guide 40 is partially withdrawn prior to moving the aspiration catheter 10 back and forth in the proximal and distal directions so as to dislodge thrombi 38, 38a, the step of partially withdrawing the wire guide 40 may be omitted thereby advantageously reducing the total operation time and removing the need to provide a locking mechanism.

Figure 10 shows a perspective view of the aspiration tube 22 and wire guide support of an alternative embodiment with dashed lines indicating the disposition of the wire guide support 20 within the aspiration tube 22. In this embodiment, the aspiration catheter 10 does not have a thrombus dislodging section 12 and the tube portion 20a of the wire guide support 20a does not project beyond the distal opening 24 of the aspiration tube 22. Also, instead of having a single fin portion 20b to couple the wire guide support 20 to the aspiration tube 22, a number of small fin portions 20d that are radially spaced apart and longitudinally offset are provided. As above, the distal end 20e of the most distal small fin portion 20d is proximally set back from the distal opening 24 of the aspiration tube 22. Figure 11, which shows an end view of the aspiration tube 22 of Figure 10, illustrates the radial spacing of the small fin portions 20d. As another possibility, instead of the distal end of the tube portion 20a of the wire guide support 20 being flush with the distal opening 24 of the aspiration tube 22, it may be proximally set back therefrom.

Figure 12 shows a perspective view of the aspiration tube 22 of another alternative embodiment with dashed lines indicating the disposition of the wire guide support 20 within the aspiration tube 22. In this embodiment, the aspiration catheter 10 has no thrombus dislodging section and the wire guide support 20 does not have a tube portion 20a for a wire guide 40. Instead, the wire guide support 20 comprises a plurality of small fin portions 20d like those shown in Figure 10. The small fin portions 20d are disposed to hold a wire guide 40 in a predetermined position with respect to the aspiration tube 22 50 that, at the distal opening 24 of the aspiration tube 22, the wire guide 40 is held away from the internal periphery 22a of the aspiration tube 22 to create an annular aspiration zone about the wire guide in a plane passing through the distal opening 24 of the aspiration tube 22. By virtue of the wire guide support 20 having no tube portion 20a, the flexibility of the aspiration catheter 10 may be increased compared to embodiments having such a tube portion 20a thereby enabling it be used in highly tortuous blood vessels. Also, the amount of materials needed to manufacture the aspiration catheter 10 may be reduced compared to embodiments having a tube portion 20a. A person skilled in the art will appreciate that, provided that the wire guide support 20 is arranged to hold a wire guide 40 so that an aspiration gap extends wholly around the wire guide 40 at the distal opening 24 of the aspiration tube 22, alternative shapes and configurations of wire guide support 20 may be employed. As one example, the wire guide support 20 may comprise one or more threads coupled to the internal periphery 22a of the aspiration tube 22.

As one possibility, instead of the tube portion 20a of the wire guide support 20 being coupled in a fixed relationship to the aspiration tube 22, it may be longitudinally slidable and/or rotatable with respect to the aspiration tube 22. For example, the tube portion 20a may be held spaced apart from the aspiration tube 22 by the fin portions 20d so that an aspiration zone radially surrounds the tube portion 20a at the distal end of the aspiration tube 22, and the tube portion 20a may be movable with respect to the aspiration tube 22 and the fin portions 20d so that in use, once the aspiration tube 22 is positioned proximally adjacent to a thrombus, the tube portion 20a and any tip 18 coupled thereto may be moved back and forth in the proximal-distal direction and/or rotated relative to the aspiration tube 22 so as to dislodge or break up thrombi 38, 38a. If the tip 18 of the thrombus dislodging section 12 is movable with respect to the aspiration tube 22, then, even if the thrombus 38 has substantial length in the proximal-distal direction, the aspiration tube 22 can be held in a position proximal to the thrombus 38 whilst the tip 18 is advanced into or through the thrombus 38. This avoids the situation where, for a long thrombus 38, the aspiration tube 22 is pushed into the thrombus 38 and so is unable to provide aspiration proximal to the thrombus 38. Such functionality can also be achieved by the embodiment shown in Figure 13 which has an intermediate tube portion 20f held by the fin portion 20b within the aspiration tube 22 and within which the tube portion 20a of the wire guide support 20 is longitudinally and/or radially movable. In the -10-embodiment of Figure 13, the intermediate tube portion 20e also has a number of projections 20g, preferably blades, that are arranged to cooperate with an internal surface 1 8a of a cavity 1 8b of the tip 18. Thrombi 38 that are hooked into the cavity 18b of the tip 18 can then be broken up by moving the tip 18 towards the distal opening 24 of the aspiration tube 22 so as to force the projections 20g of the intermediate tube portion 20c through the thrombi 38 and into contact with the internal surface 18a of the tip 18. During navigation to the site of the thrombus 38, the tip 18 would preferably be held against the projections 20g of the intermediate tube portion 20c so as to prevent the projections 20g from damaging healthy vessel walls.

Although the Figures show the fin portion 20b and the small fin portions 20d of the wire guide support being axially oriented, as another possibility they may be inclined to the long axis of the aspiration tube 22, for example to form one or more thread-like portions. In such cases, the fin portions 20b, 20d may be arranged to act as baffles to create a predetermined flow pattern within the aspiration tube 22 when an aspiration force is applied to the proximal end thereof. By creating a predetermined flow pattern within the aspiration tube 22, the flow pattern of blood located within the blood vessel 36 but distal to the distal opening 24 of the aspiration tube 22 may be controlled to cause the blood to swirl into aspiration tube 22 or to encourage thrombi 38, 38a to lift away from the wall of the blood vessel 36 or to break up. By causing blood to swirl into the aspiration tube 22, the aspiration catheter 10 may be able to radially draw thrombi 38, 38a that otherwise may have escaped aspiration into the aspiration tube 22. If the fin portions 20b, 20d are inclined to the long axis of the aspiration tube 22 so as to have no distally facing facets that lie in the radial plane of the aspiration catheter 22, then the chances of the aspiration tube 22 becoming clogged up by aspired thrombi 38, 38a may be reduced as aspired thrombi 38, 38a coming into contact with the fin portions 20b, 20d will be deflected in a direction having a proximal component; if however, the fin portions 20b, 20d do have distally facing facets that lie in the radial plane of the aspiration catheter 22, then aspired thrombus particles 38a coming into contact with such facets may accumulate at the -11 -facets.

A person skilled in the art will appreciate that, although the above has described the wire guide support 20 having fins portions 20b, 20d to support either the tube portion 20a of the wire guide support 20 or the wire guide 40 itself, these portions could instead have other shapes whilst still performing the same function, for example radially spaced apart spokes could be employed to support the tube portion 20a of the wire guide support 20 SO as to maintain an annular gap thereabout at the distal opening 24 of the aspiration tube 22.

To facilitate aspiration and prevent clogging of the aspiration tube 22, the internal lumen of the aspiration tube 22, the external lumen of the tube portion 20a of the wire guide support 20, and/or the fin potion(s) 20b, 20d of the wire guide support 20 may have a low friction coating such as PTFE or polyethylene, and/or a drug eluting coating, for example to elute a thrombolytic agent. To facilitate movement of the wire guide 40 within the tube portion 20a of the wire guide support 20, the wire guide 40 and/or the wire guide support 20 may have low friction coatings. If the wire guide is to be used to dislodge thrombi 38, 38a thereof, then at least the distal tip of the wire guide 40 may have a drug eluting coating, for example to elute a thrombolytic agent. To facilitate advancement and retraction of the delivery sheath 26 and the aspiration tube 22, the delivery sheath 26 may have a low friction coating on one or both of its internal and external lumen and/or the aspiration tube 22 may have a low friction coating on its external lumen.

To help the tip 18 of the thrombus dislodging section 12 to work thrombi 38, 38a free from the wall of the blood vessel 36, the tip 18 may have a textured surface and/or a rough coating. As one possibility, the tip 18 may have a drug eluting coating, for example to elute a thrombolytic agent to help dislodge thrombi 38, 38a. In addition, or alternatively to having grooves 32, the tip 18 may have one or more projecting portions (not shown), for example one or more blades or helical thread portions, to help push, pull and/or cut thrombi 38, 38a away from vessel walls. If the tip 18 has thread portions, then, during thrombus dislodgement, the tip 18 may be rotated -12 -about the longitudinal axis of the aspiration catheter 10 to bore into the thrombus 38, 38a. As one possibility, the tip 18 may have proximally facing barbs or hooks, for example at edge 34, arranged to allow distal advancement of the tip 18 past a thrombus 38, 38a and to impede proximal retraction of the tip 18 past the thrombus 38, 38a. Although the above has described the tip 18 as being frustoconical shaped with a curved distal end, the tip 18 need not be so shaped and a person skilled in the art will appreciate alternative shapes that the tip 18 may have such as conical, cylindrical, egg shaped etc.. A person skilled in the art will appreciate that in embodiments not having a thrombus dislodging section 12 with a tip 18, any combination of the above described features of the tip 18 may equally be provided on the tube portion 20a of the wire guide support 20.

In embodiments where the wire guide support 20 does not have a tube portion 20a, or where the tube portion 20a is proximally set back from the distal opening 24 of the aspiration tube 24, to aid thrombus removal the distal end of the aspiration tube 22 may itself have one or more projections, and/or may have a textured surface, a rough coating, and/or a drug eluting coating, for example to elute a thrombolytic agent. If the distal end of the aspiration tube 22 does have projections, a textured surface and/or a rough coating, preferably these are arranged so as to minimise contact with, and damage to, healthy vessel walls whilst the aspiration tube 22 is advanced to, and retracted, from the site of the thrombus 38, for example by being longitudinally oriented.

Figure 14 shows an alternative embodiment of the thrombus dislodging section 12, in which, although the tube portion 20a of the wire guide support 20 projects distally beyond the distal opening 24 of the aspiration tube 22, there is no distinct tip formation. The tube portion 20a of the wire guide support 20 comprises a marker 44, 46 to facilitate visualisation of the distal end of the aspiration catheter 10 when viewed using an imaging modality, such as X-ray, ultrasound, or magnetic resonance. In this example, the marker 44, 46 is a pair of bands of radiopaque material, one of which is larger than the other to enable an operator to determine the orientation of the aspiration catheter 10. -13-

The tip 18 of the thrombus dislodging section 12 and/or at least the distal end of the aspiration tube 22 and/or the tube portion 20a of the wire guide support 20 may be made of a radiopaque material such as a plastic material having a metal component, for example a 4:1 mixture of tungsten and nylon. Other preferred materials for the aspiration tube 22, tip 18, and wire guide support 20 include: nylon, polyurethane, and/or polyethylene.

In a preferred manner of manufacture, the aspiration tube 22 and wire guide support are co-extruded so as to be integral. In cases where one or more surfaces of the aspiration tube 22 and/or the wire guide support 20 are to be provided with a coating, such as a low friction coating or a drug eluting coating, this may be provided during extrusion. For example, the inner lumen of the aspiration tube 22 and the external lumen of the tube portion 20a of the wire guide support 20 may be provided with a PTFE coating during extrusion. In cases where the aspiration tube 22 and the fin portions 20b, 20d of the wire guide support 20 have been co-extruded so that one or more fin portions 20b, 20d extend to the distal end of the aspiration tube 22, distal portions of these fin portions 20b, 20d would preferably then be removed, for example by cutting, to ensure that the distal end 20c, 20e of the most distal part of the fin portions 20b, 20d is proximally set back from the distal opening 24 of the aspiration tube 22. If the aspiration catheter 10 has a tip 18, then the tip 18 is preferably moulded and is preferably fixed to the tube portion 20a of the wire guide support 20 by gluing or welding.

As one possibility, instead of the fin portions 20b, 20d being proximally set back from the distal opening 24 of the aspiration tube 22, the fin portions 20b, 20d may be flush with the distal opening 24 of the aspiration tube 22 and the distal opening 24 of the aspiration tube 22 may be proximally set back from the distal end of the aspiration catheter 10, for example by being located proximal of the tip 18 of the thrombus dislodging section 12.

As one possibility, instead of partially withdrawing the distal tip of the wire guide 40 prior to aspiration, the wire guide 40 itself may be employed to work thrombi 38, 38a -14 -free from the wall of the blood vessel 36. In such cases, the wire guide 40 may have a hardened tip, for example the wire guide 40 may be made of made of NiTi and have a platinum tip. The distal tip of the wire guide 40 may be shaped so as to have a diameter greater than that of the rest of the wire guide 40 and may have an attachment having any of the attributes described herein of the thrombus dislodging section's tip 18.

As one possibility, the aspiration tube 22 could be longitudinally subdivided into a plurality of aspiration lumen, for example by the provision of partitions, which may form part of the wire guide support 20, within the aspiration tube 22. In such cases, the partitions would be arranged so as to provide an annular aspiration zone in the radial plane at the distal end 24 of the aspiration tube 22. The partitions may be radially spaced apart so as to make the force required to longitudinally bend the aspiration tube 22 substantially independent of the rotational orientation of the aspiration tube 22 with respect to its longitudinal axis -i.e. to make the radial stiffness of the aspiration tube 22 substantially uniform. Advantageously, because the amount of force required to longitudinally bend such an aspiration tube 22 is substantially uniform, during navigation to/from the thrombus site, the aspiration tube 22 is unlikely to judder or unexpectedly straighten as may occur when catheters having non-uniform radial stiffnesses are navigated through curved vessels.

Preferably, the tube portion 20a of the wire guide support 20 is coaxial with the aspiration tube, however a person skilled in the art will appreciate that, provided that the gap between a wire guide 40 held by the wire guide support 20 and the distal end of the aspiration tube has an annular form, the tube portion 20a may be otherwise arranged.

A person skilled in the art will appreciate that although the catheter 10 may be configured for "over the wire" deployment -with the wire guide support 20 being arranged to support a wire guide 40 within substantially the entire length of the aspiration tube 22-additionally or alternatively, the catheter 10 may be arranged for "rapid exchange" deployment, in which case the wire guide support 20 would be -15-arranged to support a wire guide 40 within only a distal portion of the aspiration tube 22 (for example the distal 10 to 22 cm of the aspiration tube 22) and the aspiration tube 22 would have a port (not shown) to enable the wire guide 40 to pass to the exterior of the aspiration tube 22 so that in use the wire guide 40 lies outside the aspiration tube 22 at locations proximal to the port. In such cases, the portion of the aspiration tube 22 proximal to the port may have no wire guide support and may simply be tube shaped so as to have a large unobstructed internal aspiration lumen and may be made, for example, from a braided material.

A person skilled in the art will appreciate that any of the above alternatives may be employed either alone or in combination. -16-

Claims

Claims 1. An aspiration catheter comprising: an aspiration passageway having a distal end; and a wire guide support within the passageway, the wire guide support being arranged to support a wire guide so that, at least at the distal end, the aspiration passageway extends wholly around the wire guide.
2. The aspiration catheter of claim 1, wherein the distal end of the aspiration passageway has an annular form about the wire guide.
3. The aspiration catheter of claim 1, wherein the wire guide support has a tip arranged to project distally of the distal end of the aspiration passageway.
4. The aspiration catheter of claim 3, wherein the tip has a textured or grooved surface.
5. The aspiration catheter of claim 3, wherein the tip has one or more projections, the one or more projections preferably being blades or threads.
6. The aspiration catheter of claim 3, wherein the tip has a rounded portion at its distal end.
7. The aspiration catheter of claim 3, wherein the tip has a proximally facing edge, hook, and/or barb.
8. The aspiration catheter of claim 3, wherein the tip has a drug eluting surface, the drug preferably being a thrombolytic agent.
9. The aspiration catheter of claim 3, wherein the tip has one or more radiopaque markers or is made of a radiopaque material. -17-
10. The aspiration catheter of claim 1, wherein the distal end of the aspiration passageway surround has a drug eluting surface, the drug preferably being a thrombolytic agent.
11. The aspiration catheter of claim 1, wherein the distal end of the aspiration passageway surround has a textured surface, the textured surface preferably comprising one or more projecting elements.
12. The aspiration catheter of claim 1, wherein the wire guide support comprises a tubular portion for the wire guide.
13. The aspiration catheter of claim 12, wherein the tubular portion of the wire guide support is movable with respect to the aspiration passageway surround.
14. The aspiration catheter of claim 13, further comprising: a first engagement surface coupled to the aspiration passageway surround; and a second engagement surface coupled to the tubular portion of the wire guide support, wherein the tubular portion of the wire guide support is movable with respect to the aspiration passageway surround between a first configuration in which the first and second engagement surfaces are apart and a second configuration in which the first and second engagement surfaces are in contact.
15. The aspiration catheter of claim 1, further comprising one or more baffles arranged within the passageway to affect aspiration flow therein.
16. The aspiration catheter of claim 15, wherein one or more of the one or more baffles is arranged so as to have no distally facing surfaces that lie in a radial plane of the aspiration catheter. -18-
17. A kit for aspirating matter from a body vessel comprising: the aspiration catheter of claim 1; and a wire guide.
18. The kit of claim 17, wherein the distal tip of the wire guide is harder than a proximal region of the wire guide, the tip preferably comprising platinum.
19. The kit of claim 17, wherein the wire guide has an enlarged tip portion for breaking up and/or dislodging thrombi and/or emboli, the tip preferably being textured to have protrusions and/or grooves.
20. A method of aspirating matter from a body vessel, the method comprising: navigating a wire guide to a position in the vessel adjacent to the matter to be aspired; positioning an aspiration catheter adjacent to the matter using the wire guide; providing an aspiration force at a proximal end of an aspiration passageway of the aspiration catheter so as to effect aspiration at a distal end of the aspiration passageway in a zone that radially surrounds the wire guide; and aspiring the matter into the aspiration passageway for removal from the vessel.
21. The method of claim 20, further comprising moving the aspiration catheter or a portion thereof and/or the wire guide in a proximal-distal direction to contact the matter and dislodge it and/or break it up.
22. An aspiration catheter comprising: means for transferring an aspiration force from a proximal portion of the catheter to a distal end portion thereof; and means for supporting a wire guide within the transferring means, the aspiration catheter being operable, when a wire guide is supported by the -19-supporting means, to effect, at the distal end of the passageway, aspiration in an annular profile about the wire guide.Amendments to the claims have been filed as follows Claims 1. An aspraton catheter comprising: an aspraton passageway having a dsta end; and a wre guide support wfthn the passageway, the wfre guide support being fixed reatve to the aspraton passageway and arranged to support a wire guide so that, at east at the dsta end, the asprafion passageway extends whoHy around the wire gude.2. The aspiration catheter of cam 1, wherein the dsta end of the aspraton passageway has an annu'ar form about the wire guide.3. The aspraton catheter of cam 1, wherein the wire gukie support has a tp arranged to project dstaVy of the dsta end of the aspraton passageway.4. The aspraton catheter of caim 3, wheren the tip has a textured or grooved surface.5. The aspiration catheter of cam 3, wherein the tp has one or more projectons, the one or more projectons preferaby being b'ades or threads.6. The aspraton catheter of cam 3, wherein the tip has a rounded portion at its dsta end.7. The aspration catheter of cam 3, wherein the fip has a proxmaDy facing edge, hook, and/or barb.8. The aspiration catheter of cam 3, wheren the fip has a drug eufing surface, the drug preferably being a thromboytc agent.9. The aspraton catheter of cam 3, wher&n the tp has one or more radiopaque markers or is made of a radiopaque materiaL 10. The aspiration catheter of claim 1, wherein the dista end of the aspiration passageway surround has a drug eluting surface, the drug preferably being a thrombolytic agent.11. The aspiration catheter of claim 1, wherein the distal end of the aspiration passageway surround has a textured surface, the textured surface preferably comprising one or more projecting elements.12. The aspiration catheter of claim 1, further comprising a tube for the wire guide and wherein the wire guide support is arranged to support the tube.13. The aspiration catheter of claim 12, wherein the tube is movable with respect to the aspiration passageway surround.14. The aspiration catheter of claim 13, further comprising: a first engagement surface coupled to the aspiration passageway surround; and a second engagement surface coupled to the tube, wherein the tube is movable with respect to the aspiration passageway surround between a first configuration in which the first and second engagement surfaces are apart and a second configuration in which the first and second engagement surfaces are in contact.15. The aspiration catheter of claim 1, further comprising one or more baffles arranged within the passageway to affect aspiration flow therein.16. The aspiration catheter of claim 15, wherein one or more of the one or more baffles is arranged so as to have no distally facing surfaces that lie in a radial plane of the aspiration catheter.17. A kft for aspratng matter from a body vesse' compr&ng: the aspraton catheter of c'aim 1; and a wire gude.18. The kit of c'aim 17, wheren the dista' tip of the wire guide is harder than a proxima' regon of the wire guide, the fip preferaby comprising patinum.19. The kit of caim 17, wherein the wire guide has an enarged tip portion for breaking up and/or dis'odging thrombi and/or emboU, the tip preferabty being textured to have protrusions and/or grooves.