Removing obstructions from blood vessels

Abstract

An endovascular thrombus macerator comprises a central rod and flexible bristles. The flexible bristles extend radially from the rod at respective longitudinal positions along the rod. The bristles vary in their radial extent from the rod, and hence length, in accordance with their longitudinal positions along the rod.

Description

[0001] Removing obstructions from blood vessels

[0002] This invention relates to systems and methods for removing obstructions from blood vessels. The invention relates particularly to systems and methods that can mechanically remove blood clots, restoring blood flow to a blood vessel. Optionally, the system and method can be combined with chemical techniques.

[0003] Deep Vein Thrombosis (DVT) is a medical condition that occurs when a blood clot (thrombus) forms inside the deep veins of the body, blocking or partially blocking the flow of blood back to the heart and lungs. It is the third most common cardiovascular disease after heart attack and stroke, with a significant number of cases diagnosed each year in the Ell and US alone.

[0004] If left untreated, one-third of DVT patients will be at risk of thrombus breaking away and blocking the lungs pulmonary artery. This is known as Pulmonary Embolism (PE) which has a high mortality rate. Apart from PE, several associated chronic complications of thrombus presence can lead to a poor quality of life for the patients. This includes Post- Thrombotic Syndrome (PTS) which is an extremely debilitating condition that causes longterm pain and leg ulcers. These can ultimately lead to limb amputation.

[0005] Current treatment options for DVTs primarily include thrombolytic therapy and / or mechanical thrombectomy. However, as thrombolytic drugs have been associated with high costs and significant risks such as haemorrhage, mechanical thrombectomy has emerged as a safer alternative, particularly for large vessel occlusions. Nevertheless, stubborn clots can present a challenge to solely mechanical thrombectomy devices. For example, extraction forces can be very high.

[0006] Various mechanical thrombectomy devices have been proposed in the prior art. For example, CN 117618068 discloses a thrombus removing device that includes a pushing rod, a hollow tube and a compressible brush. Once the device is navigated to the thrombus site, the brush is pushed back and forth and rotated to engage and fragment the thrombus. A collection component wraps the clot-covered brush, and the brush is then removed with the clot from the blood vessel.

[0007] In CN 117618068 a guidewire is offset relative to and within the brush. Consequently, if left in body during a de-clotting operation (reducing risk of vessel perforation during advancement), the guidewire must rotate with the brush around a central axis. This creates an uncontrolled ‘helicopter’ effect that can cause snagging within the vessel, prejudices sterility and makes the device difficult to use.

[0008] US 2005165431 discloses a collapsible device that removes blockage-forming material from a vessel wall and improves blood flow by drawing the removed material into a catheter. The device adapts to varying vessel sizes and includes bristles arranged in a spiral configuration to remove the blockage-forming material from the wall of the vessel. During device retraction, the larger profile of the proximal bristles can quickly lead to the thrombus plugging at the user end of the brush, generating ineffective removal of material. The device is advanced without a guidewire in place which can cause mechanical trauma, damaging the vessel wall and leading to perforation.

[0009] CA 2256131 is an example of prior art that uses a combination of mechanical and chemical techniques to remove blood clots. Specifically, it describes a miniaturised brush for insertion into blood vessels to remove soft fibrinous obstructions. The brush is rotated within the thrombus to separate fibrin from blood cells and a thrombolytic agent dissolves the separated fibrin. As the brush is fully deployed as it enters the clot, it may unintentionally push the clot forward, risking embolic release. During device retraction, the proximal bristles can quickly lead to the thrombus plugging at the user end of the brush, generating ineffective removal of material.

[0010] US 2009149807 describes a balloon catheter system that uses fluid pressure to inflate and deflate the balloon. The system employs high-velocity jet streams of saline emitted from a fluid jet emanator to dislodge thrombotic deposits. The jets create internal pressure, and the fluid inflates the balloon. The pressure facilitates circulation of thrombus deposits and directs them into the lumen of a catheter for removal. The process is slow due to the time needed for the jet streams of saline to create channels within the thrombus. Additionally, as a significant amount of saline is required to break down the clot in its entirety, and as there is prolonged exposure of tissues to high-pressure fluid, the cost and risk of haemorrhage increases.

[0011] EP 1251892 describes an apparatus for clot dissolution. The apparatus includes a catheter and a rotatable agitator that mechanically agitates the clot. The catheter includes ports that deliver thrombolytic agent directly to the location where the thrombus is being disrupted. Despite employing a combination of mechanical and chemical techniques, channels created in the clot during agitation do not have sufficient surface area for effective lytic treatment. As with US 2009149807, a larger volume of thrombolytic agent is required, which can lead to increased costs and risk of haemorrhage.

[0012] In an even more complex example, US 11826065 describes an infusion catheter for dissolving large volume clots in large vessels. The catheter includes multiple eluting arms that deliver therapeutic agents. Each eluting arm has multiple infusion ports fluidly connected to a lumen of each eluting arm. The use of a catheter with multiple lumens and infusion ports complicates the operation of the device, making it more difficult to use effectively compared to simpler designs. Additionally, delivering a high concentration of therapeutic agents to a localised area can cause damage to the surrounding tissues.

[0013] US 8361095 describes a loop thrombectomy device that consists of an elongated torsion member with helically arranged engagement members. The engagement members expand and collapse to capture and remove thrombi from blood vessels. During device retraction, the larger profile of the proximal bristles can quickly lead to the thrombus plugging at the user end of the brush, generating ineffective removal of material. The device is advanced without a guidewire in place which can cause mechanical trauma, damaging the vessel wall and leading to perforation.

[0014] US 5370653 describes a catheter system that delivers high-velocity fluid jets to dislodge clots. The catheter has multiple jet openings positioned at different angles to direct the flow of fluid towards the clot, effectively breaking it up and allowing it to be aspirated out. However, the use of high-velocity fluid jets can increase the risk of vessel wall injury and haemorrhage. Furthermore, a substantial amount of fluid is required, which can lead to increased costs.

[0015] Other prior art of more general relevance includes WO 9834674 and ON 103732159.

[0016] Against this background, the invention resides in an endovascular thrombus macerator and method of macerating a thrombus in a blood vessel. The macerator comprises a central rod and flexible bristles extending radially from the rod at respective longitudinal positions along the rod, wherein the bristles vary in their radial extent from the rod, and hence length, in accordance with their longitudinal positions along the rod. The length of the bristles may vary continuously in a longitudinal direction along the rod. Alternatively, the length of the bristles may vary stepwise in a longitudinal direction along the rod.

[0017] The bristles may be grouped into two or more groups disposed in longitudinal succession along the rod. The bristles of one of the groups may have a first length and the bristles of another of the groups may have a second length, being different from the first length. Preferably, the bristles of a distal one of the groups have a greater length than the bristles of a proximal one of the groups. Additionally, the groups may be spaced apart along the rod in longitudinal succession.

[0018] The bristles at an end of at least one of the groups may be stiffer and / or more densely packed than the bristles within a body of that group. The stiffer or more densely packed bristles may be disposed at a junction between successive groups. Distally disposed bristles may be stiffer or more densely packed than proximally disposed bristles.

[0019] Beneficially, the bristles may be deformable or deflectable. The bristles may extend radially outwardly and proximally at an acute angle relative to a longitudinal axis of the rod. The bristles may be deflectable from an initial position at a lesser angle to the longitudinal axis of the rod to an extended position at a greater angle to the longitudinal axis of the rod.

[0020] The macerator may also include at least one disruptor extending radially from the rod, the or each disruptor being substantially rigid. The or each disruptor may have substantially the same radial extent from the rod, and hence length, as adjoining bristles.

[0021] The or each disruptor may comprise radially extending arms. The arms may be substantially straight or curved, for example curved about longitudinal axes. The arms may be in cruciform relation and may be pivotable relative to the rod. The arms may have bulbous or hooked radially outer ends.

[0022] Advantageously, the macerator may include at least two of the disruptors in mutually adjacent longitudinal succession. The mutually adjacent disruptors may have arms that are angularly offset from each other about the rod. The or each disruptor may be disposed within a respective group of the bristles. The or each disruptor may be offset toward an end of the respective group of the bristles. Alternatively, the or each disruptor may be disposed between the successive groups of the bristles in a space between those groups.

[0023] The macerator may comprise distally disposed disruptors and proximally disposed disruptors, wherein the distally disposed disruptors may be of greater length than the proximally disposed disruptors. The macerator may also include distally disposed bristles and proximally disposed bristles, wherein the distally disposed bristles are of greater length than the proximally disposed bristles.

[0024] The bristles may be arranged helically along the rod. The bristles may be arranged in loops around the rod, the bristles of each loop being of substantially constant length from the rod or of varying length from the rod.

[0025] The rod may comprise wires twisted together about a longitudinal axis.

[0026] Conveniently, the bristles of at least one of the groups may be more densely packed than the bristles of another of the groups. The groups with more densely-packed bristles may alternate longitudinally along the macerator with groups having less densely-packed bristles. The more densely-packed bristles may be less stiff than the less densely-packed bristles.

[0027] The bristles may vary in their radial extent around the circumference of the rod.

[0028] The inventive concept may also be expressed as an endovascular macerator comprising a central rod and flexible bristles extending radially from the rod at respective longitudinal positions along the rod, wherein the bristles are grouped into two or more groups disposed in longitudinal succession and spaced apart along the rod.

[0029] The groups may be spaced apart along the rod in longitudinal succession.

[0030] The bristles of one of the groups may be stiffer than the bristles of another of the groups. The bristles of a distal one of the groups may be stiffer than the bristles of a proximal one of the groups. The inventive concept also embraces a corresponding method of macerating a thrombus. The method involves using a macerator that has bristles extending radially and proximally at acute angles to a longitudinal axis, wherein the bristles vary in length in accordance with their longitudinal positions along the axis, proximal bristles being shorter than distal bristles, and drawing the macerator proximally through the thrombus to engage material of the thrombus by deflecting the bristles from initial positions at a lesser angle to the longitudinal axis to extended positions at a greater angle to the longitudinal axis.

[0031] The method may include engaging a radially inner portion of the thrombus with the proximal bristles and subsequently engaging a radially outer portion of the thrombus with the distal bristles during proximal movement of the macerator through the thrombus. The method may also comprise turning the macerator about the longitudinal axis.

[0032] Advantageously, the method may also include wrapping the thrombus material around the bristles. The method may further comprise turning the macerator alternately in opposite angular directions. The method may also include deploying the macerator at least partially within the thrombus. The method may further comprise engaging the thrombus material with the proximal bristles and the distal bristles simultaneously when drawing the macerator proximally through the thrombus. The method may include deploying the macerator distally with respect to the thrombus.

[0033] The method may further comprise engaging the thrombus material initially with the proximal bristles and subsequently with the distal bristles when drawing the macerator proximally through the thrombus. The method may also include chopping the thrombus material with at least one rigid disruptor mounted on the rod.

[0034] The method may be followed by drawing the macerator, carrying the macerated thrombus, proximally into a sheath. The method may further comprise cutting thrombus material with a distal end of the sheath. The method may also include withdrawing the macerator, carrying the macerated thrombus, from a proximal end of the sheath. Quick withdrawal of the macerator will naturally aspirate residual clot into the sheath. The method may also comprise aspirating the macerated thrombus through the sheath using a separate device, attachable to the handle, like a manual syringe or vacuum pump.

[0035] Conveniently, the method may also comprise generating an aspirating flow by withdrawing the macerator, carrying the thrombus material, proximally along the sheath. The method may further comprise advancing a sheath distally through a residual thrombus, redeploying the macerator from the sheath to engage with the residual thrombus, applying aspiration through the sheath, and drawing the macerator proximally to capture the residual thrombus and to draw the residual thrombus into the sheath.

[0036] Optionally, the method may also include advancing a sheath distally through a residual thrombus, deploying a secondary macerator from the sheath to engage the residual thrombus, applying aspiration through the sheath, and drawing the secondary macerator proximally to capture the residual thrombus and to draw the residual thrombus into the sheath.

[0037] The method may further comprise engaging the thrombus material initially with relatively stiff bristles and subsequently with more flexible bristles

[0038] The invention also provides a method of performing a thrombectomy, the method comprising: advancing an endovascular guidewire distally across a thrombus to bring a distal end of the guidewire to a distal side of the thrombus; advancing a catheter distally along the guidewire , the catheter comprising a distal tip and an outer sheath containing a major lumen that confines a macerator in a radially-contracted state and a minor lumen along which the guidewire extends, the minor lumen being offset laterally from the major lumen; withdrawing the guidewire proximally through the distal tip of the catheter and along the minor lumen to bring the distal end of the guidewire to a proximal side of the macerator; deploying the macerator from within the catheter into a radially-expanded state by withdrawing the outer sheath proximally relative to the macerator; engaging the thrombus with the macerator; and withdrawing the macerator proximally while removing the thrombus.

[0039] A thrombolyic agent may be expelled from the catheter and into the thrombus while crossing the thrombus or during macerator deployment.

[0040] The macerator may be deployed on the distal side of or within the thrombus before being withdrawn proximally into engagement with the thrombus.

[0041] The macerator and the thrombus can be withdrawn through an evacuation channel in a handle of the catheter at a proximal end of the outer sheath, the evacuation channel being coaxial with and communicating with the major lumen of the catheter. The macerator and the thrombus can be removed through a proximal valve that seals the evacuation channel.

[0042] The guidewire can be moved proximally along a guidewire channel of the handle while withdrawing the guidewire along the minor lumen of the catheter, the guidewire channel being coaxial with and communicating with the minor lumen. Similarly, the guidewire can be removed through a proximal valve that seals the guidewire channel.

[0043] The distal end of the guidewire can be moved laterally during continued proximal movement of the guidewire after the distal end of the guidewire has been withdrawn through the distal tip of the catheter. The distal end of the guidewire can be aligned with a central longitudinal axis of the catheter upon passing through the distal tip of the catheter and can move laterally away from the central longitudinal axis toward alignment with the minor lumen with continued proximal movement of the guidewire.

[0044] In order that the invention may be more readily understood, reference will now be made, by way of example, to accompanying drawings in which:

[0045] Figure 1 is a perspective view of a thrombectomy device in a first embodiment of the invention;

[0046] Figure 2 a cut-away perspective view of the device of Figure 1 ;

[0047] Figures 3a and 3b are perspective views of a catheter tip of the device of Figures 1 and 2;

[0048] Figures 3c and 3d are side views of the catheter tip of Figures 3a and 3b;

[0049] Figure 4 is an enlarged detail perspective view of a distal end of an outer sheath of the device of Figure 1 ;

[0050] Figure 5 is an enlarged detail perspective view of a catheter and a guidewire disposed in a handle of the device of Figure 1 ;

[0051] Figures 6a and 6b are side views in longitudinal section of a macerator of the device being pushed into and advancing distally through the handle; Figures 7a and 7b are side views in longitudinal section of the macerator engaged with an obstruction being retracting proximally through and pulled out of the handle;

[0052] Figures 8a to 8d are a sequence of schematic side views in longitudinal section that illustrate retraction of the guidewire through the catheter tip and into the outer sheath;

[0053] Figures 8e to 8g are a sequence of schematic side views in longitudinal section that illustrate the guidewire bring advanced from the outer sheath and back through the catheter tip;

[0054] Figure 9 is a perspective view of the macerator in a deployed state;

[0055] Figure 10 is a perspective view of a macerator handle of the device of Figures 1 and 2;

[0056] Figures 11a to 11v are a sequence of schematic side views that illustrate how a device of the invention can remove obstructions from a blood vessel;

[0057] Figure 12 is a cut-away perspective view of the macerator engaged with an obstruction within the blood vessel;

[0058] Figure 13 is a perspective view in longitudinal section of the obstruction shown in Figure 12, showing channels formed within the obstruction by the action of the macerator;

[0059] Figures 14a to 14e are schematic side views of macerator variations;

[0060] Figure 15a is a side view of a macerator with bristles arranged in a narrow pitch;

[0061] Figure 15b is a side view of the macerator of Figure 15a with the bristles deflected into overlapping, parallel relation;

[0062] Figure 16a is a side view of a macerator with bristles arranged in a wide pitch; Figure 16b is a side view of the macerator of Figure 16a with the bristles deflected into series relation;

[0063] Figures 17, 18, and 19 are schematic side views of staggered macerator variations;

[0064] Figure 20 is a perspective view of a staggered macerator with dense bristles at interface points;

[0065] Figures 21 , 22 and 23 are perspective views of a staggered macerator with a variation of interface disruptors;

[0066] Figures 24a to 24d are a sequence of schematic side views that illustrate expansion of the interface disruptor;

[0067] Figures 25a, 26a, 27a, 28a and 29a are schematic side views of interface disruptor variations integrated into a macerator;

[0068] Figures 25b, 26b, 27b and 28b are perspective views of the macerators of Figures 21 , 22, 23, 24a and 25a, respectively;

[0069] Figure 29a is a schematic side view of a macerator with a short wrapping brush profile;

[0070] Figure 29b is a plan view of the macerator of Figure 29a;

[0071] Figure 29c is a perspective view of the macerator of Figures 29a and 29b;

[0072] Figure 30 is a perspective view of a multi-macerator configuration;

[0073] Figure 31 is a perspective view of a macerator with Nitinol tubing components;

[0074] Figure 32a is a schematic side view of a macerator with Nitinol tubing in a loaded configuration; Figure 32b is a schematic side view of the macerator of Figure 32a in a deployed configuration;

[0075] Figure 33 is a perspective view of the Nitinol tubing shown in Figure 31 ;

[0076] Figure 34 is a plan view of the Nitinol tubing of Figure 31 in a deployed configuration;

[0077] Figures 35a to 35I are a sequence of schematic side views that illustrate how a device with a staggered macerator can remove obstructions from a blood vessel;

[0078] Figures 36a to 40b are a sequence of perspective views that illustrate retraction of the guidewire through variations of a catheter tip and into an outer sheath;

[0079] Figure 41 is a schematic side view of a catheter assembly variation with a reduced profile device protruding from an outer sheath;

[0080] Figure 42a is a perspective view of a tapered outer sheath tip;

[0081] Figure 42b is a cut-away perspective view of the tapered outer sheath tip of Figure 42a;

[0082] Figure 42c is a cut-away perspective view of the tapered outer sheath tip of Figures 42a and 42b, with a reinforcement tube;

[0083] Figure 43a and 43b are cut-away perspective views of a low durometer atraumatic tube of the tapered outer sheath tip;

[0084] Figures 44a to 44d are a sequence of schematic side views that illustrate how a staggered macerator in various configurations can capture and remove obstructions from a blood vessel;

[0085] Figure 45a is a schematic side view of a staggered macerator in a deployed configuration; Figure 45b is a perspective view of the staggered macerator of Figure 45a in the deployed configuration;

[0086] Figures 46a and 46b are schematic side views of staggered macerator variations in a locked-in configuration;

[0087] Figure 46c is a perspective view of the staggered macerator of Figures 46a and 46b in the locked-in configuration;

[0088] Figure 47a is a perspective view of a macerator in a deployed configuration;

[0089] Figure 47b is a perspective view of the macerator of Figure 47a in a locked-in configuration;

[0090] Figures 48a and 48b are schematic side views of a staggered macerator in a snag-and-collect configuration;

[0091] Figures 49a to 49m are a sequence of schematic side views that illustrate how a device with a staggered macerator can remove obstructions from a blood vessel;

[0092] Figures 50a and 50b are perspective views of a staggered macerator with bristles that vary in length moving circumferentially around a central axis;

[0093] Figure 50c is an end view of the macerator of Figures 50a and 50b;

[0094] Figure 50d is a top view of the macerator of Figures 50a to 50c;

[0095] Figure 50e is a side view of the macerator of Figures 50a to 50d;

[0096] Figures 51a and 51b are perspective views of a variant of the macerator of Figures 50a to 50e;

[0097] Figure 51 c is an end view of the macerator of Figures 51 a and 51b;

[0098] Figure 51 d is a top view of the macerator of Figures 51a to 51c; Figures 51 e is a side view of the macerator of Figures 51a to 51 d;

[0099] Figures 52a and 52b are perspective views of a further variant of the macerator of Figures 50a to 50e;

[0100] Figure 52c is an end view of the macerator of Figures 52a and 52b;

[0101] Figure 52d is a top view of the macerator of Figures 52a to 52c;

[0102] Figure 52e is a side view of the macerator of Figures 52a to 52d;

[0103] Figure 53a is a perspective view of a staggered macerator in a deployed configuration with alternating zones of bristle density and stiffness;

[0104] Figure 53b is a side view of the macerator of Figure 53a;

[0105] Figure 54a is a perspective view of the macerator of Figures 53a and 53b in a locked-in configuration; and

[0106] Figure 54b is a side view of the macerator of Figure 54a, also in the locked- configuration.

[0107] Figures 1 and 2 show a thrombectomy device 10 with a distal portion positioned in a blood vessel 2. The device 10 shown in these figures includes a device handle 14, a catheter assembly 43, and a macerator assembly 20. The device handle 14, also shown in Figures 6a to 7b, is used to position and steer the device 10 within the vasculature. As shown in Figure 1 , the device handle 14 is contoured to fit comfortably in a user’s hand.

[0108] As shown in Figure 2, the device handle 14 includes a major channel 46 dimensioned to accommodate the macerator assembly 20, and a minor channel 44 dimensioned to receive a guidewire 4. The major channel 46 extends longitudinally through the device handle 14, and the minor channel 44 is inclined away from the major channel 46 in the proximal direction. The minor channel 44 extends from the proximal end of the device handle 14 to converge with the major channel 46 at a location proximal to the distal end of the device handle 14. The catheter assembly 43, also shown in Figures 8a to 8g, is used to cross the obstruction 12. The catheter assembly 43 includes an outer sheath 8 extending distally from the device handle 14. In Figure 1 , the outer sheath 8 can be seen extending through the obstruction 12. The catheter assembly 43 further comprises a distally-tapered catheter tip 6 to aid penetration of the obstruction 12. A proximal end of the tip 6 is releasably attached to a distal end of the outer sheath 8.

[0109] The catheter assembly 43 is advanced along a guidewire 4 that has already crossed through the obstruction 12, as shown in Figures 1 and 2. The guidewire 4 extends through a central aperture of the catheter tip 6, along the length of the outer sheath 8 and into the minor channel 44 of the handle 14 to emerge from the proximal end of the device handle 14, which remains outside a patient’s body.

[0110] The macerator assembly 20 is used to engage the obstruction 12. The macerator assembly 20, also shown in Figures 9 and 10 comprises a macerator 48 in the form of a brush arranged to engage an obstruction 12. The macerator assembly 20 further comprises a rod 50 that supports the macerator 48, and a macerator handle 18 at a proximal end of the rod 50. The proximal end of the rod 50 carrying the macerator handle 18 protrudes from the proximal end of the device handle 14. In this example, the rod 50 is a twisted wire that is surrounded by a tubular jacket 16 to minimise friction within the blood vessel 2.

[0111] The macerator handle 18 advances and retracts the macerator 48 into and out of the blood vessel 2 along the major channel 46 of the device handle 14. In Figure 1 , the macerator 48 is in an undeployed state, surrounded by, and constrained radially within the outer sheath 8. In Figure 2, the outer sheath 8 is retracted to release the macerator 48 into a radially-expanded deployed state.

[0112] Turning to Figures 3a to 3d, the catheter tip 6 is shown. A conical portion 22 of the catheter tip 6 is in fixed relation to a tubular portion 24 of the catheter tip 6. The conical portion 22 is a distally-tapered structure with an aperture on a central longitudinal axis of the catheter tip 6, through which aperture the guidewire 4 passes. Specifically, the distal end of the conical portion 22 has an opening 32 for the guidewire 4 and a rounded tip 26 to minimise friction within the blood vessel 2. The proximal end of the distal portion opens to a distal end of the tubular portion 24. The tubular portion 24 of the catheter tip 6 is a trough-like structure. The distal end of the tubular portion 24 opens to meet the proximal end of the conical portion 22. A junction between the tubular portion 24 and the conical portion 22 comprises a frustoconical deflection ramp 28 that guides the guidewire 4 into and out of the conical portion 22.

[0113] A proximal end of the tubular portion 24 includes an offset fluoroscopic marker band 34 to align the tip 6 and the guidewire 4 for reinsertion. To ensure proper alignment for guidewire 4 re-insertion, the device handle 14 is laid flat at user end and the offset marker band 34 is positioned by rotating the macerator handle 18 to be on top and away circumferentially from the guidewire 4. The proximal end of the tubular portion 24 also includes a formation 30 positioned on the central longitudinal axis to receive a distal end of the macerator 48.

[0114] Figure 4 shows the distal end of the outer sheath 8 of the catheter 43. In this example, the outer sheath 8 has two lumens 36, 38 that extend longitudinally through the outer sheath 8. A minor lumen 36 accommodates the guidewire 4 and is offset laterally from a central longitudinal axis of the outer sheath 8. A major lumen 38 accommodates the macerator assembly 20 and is offset from the central longitudinal axis of the outer sheath 8.

[0115] Offsetting the minor lumen 36 allows the guidewire 4 to be retracted proximally from a deployment area, allowing the macerator 48 to work effectively without the guidewire 4 wrapping around the rotating macerator 48. The guidewire 4 can then be readvanced distally from the outer sheath 8 after maceration has been completed. In this, the catheter 43 does not have to be removed completely from the body, which therefore saves time, reduces blood loss and lowers the risk of an air embolism.

[0116] An outer edge of the distal end of the outer sheath 8 includes an atraumatic rim 40, designed to attach to the catheter tip 6. The rim 40 also includes infusion ports 42 that face radially outwardly to emit therapeutic or thrombolytic agents directly into the obstruction. Examples of such agents include tissue plasminogen activator (tPA), urokinase, and streptokinase.

[0117] Figure 5 shows the catheter 43 disposed in the device handle 14. The macerator assembly 20 runs distally through the major channel 46 of the handle 14 and into the proximal end of the outer sheath 8 along the major lumen 38, offset from the central longitudinal axis of the outer sheath 8. The guidewire 4 runs distally through the minor channel 44 of the handle 14 and into the proximal end of the minor lumen 36 of the outer sheath 8.

[0118] Next, in Figures 6a and 6b the macerator assembly 20 is shown entering into and advancing through the handle 14. As the macerator assembly 20 enters the handle 14 distally through the major channel 46, the bristles of the macerator 48 fold over and crimp, overlapping each other. As the macerator assembly 20 advances through the major channel 46 of the handle 14, the bristles remain in this collapsed state.

[0119] In Figures 7a and 7b, the macerator assembly 20 is shown retracting from and exiting the handle 14 having engaged and dislodged an obstruction 12. As the macerator 48 with the obstruction 12 is retracted from a blood vessel 2 and the handle proximally through the major channel 46, the bristles crimp. As the macerator 48 with the obstruction 12 exits the proximal end of the major channel 46, the bristles carrying the obstruction 12 expand radially to their original, expanded state. The obstruction 12 can then be observed and studied by a user.

[0120] Figures 8a to 8d are side sectional views of a guidewire 4 being retracted from the catheter tip 6 and into the outer sheath 8 of the catheter 43. The guidewire 4 is retracted proximally from blood vessel 2 and into the distal end of the catheter 43, through the conical portion 22. The guidewire 4 deflects past the frustoconical deflection ramp 28 as the guidewire 4 retracts out of the conical portion 22 and into the tubular portion 24 of the catheter tip 6.

[0121] Figures 8e to 8g are side sectional views of the guidewire 4 re-advancing into the blood vessel 2. As the guidewire 4 is advanced to the distal end of the outer sheath, the guidewire 4 comes in contact with the deflecting ramp 28, as shown in Detail A. As the guidewire 4 is pushed against the deflecting ramp 28, the guidewire 4 is deflected radially inwardly toward the opening in the distal end of the catheter tip 6. The guidewire 4 then advances through the distal end of the catheter tip 6 and into the blood vessel 2.

[0122] Figures 9 and 10 exemplify the macerator assembly 20. In Figure 9, the macerator 48 is shown. In this example, the macerator 48 is a brush whose radially-projecting bristles twist helically around the central axis of the twisted wire serving as the rod 50. By using a twisted wire, high torque is accommodated along the full length of the macerator assembly, reducing the risk of intra-shaft bond failures. Also, the profile of the rod 50 is minimised, aiding efficacy of aspiration as there is greater space for aspirated material. A reduced twisted wire profile also reduces rod 50 stiffness thereby enhancing device trackability.

[0123] The bristles project from the rod 50 with uniform radial length. This helps to maintain consistent contact with an obstruction 12 during maceration. The stiffness of the bristles is sufficient to macerate, squeeze and capture the obstruction. The obstruction 12 is thereby engaged in the gaps between the bristles. The macerator 48 is typically 4cm in length but can be anywhere from 1cm in length.

[0124] A proximal end of the tubular portion 24 of the catheter tip 6 supports the distal end of the rod 50 and a proximal end of the rod 50 is surrounded by the jacket 16. The jacket 16 reduces operational forces during torquing and retraction. The jacket 16 also aids resheathing of the brush by keeping the brush more concentric with the outer sheath 8 when entering the outer sheath 8. A proximal end of the jacket 16 is attached the macerator handle 18. Optionally, the jacket 16 can have printed markers at a user end to identify the longitudinal position of the macerator 48.

[0125] Figure 10 shows the macerator handle 18 of the assembly 20. The handle 18 is an ergonomic, contoured design that flares outwards toward its proximal end and tapers toward its distal end. The handle 18 has elongate grooves running along its length to improve grip and control. The rod 50 is anchored at its proximal end within the handle 18. The handle 18 includes a tab 52 to indicate circumferential angular orientation of the catheter tip 6 relative to the minor lumen 36 of the outer sheath 8 for re-loading the guidewire 4.

[0126] Figures 11a to 11v exemplify a process for removing an obstruction 12 from a blood vessel 2. In Figure 11a, the obstruction 12, such as a thrombus or vascular plaque, is shown in the blood vessel 2. As the obstruction 12 grows, it narrows the lumen of the blood vessel 2, restricting blood flow. This can lead to limb swelling and pain. In some cases, the obstruction can completely block the vessel 2, preventing any blood from flowing through the vessel 2. This can break away to form a pulmonary embolism that carries a high risk of death. Long term presence of thrombus can lead to chronic complications including post-thrombotic syndrome. In Figure 11b, the guidewire 4 advances through the obstruction 12. The guidewire 4 is first inserted into the vessel 2 and is navigated distally towards the obstruction 12. As the guidewire 4 advances through the obstruction 12, a distal tip of the guidewire 4 disrupts the structure of the obstruction 12, creating a small channel or path through the obstruction 12. The tip of the guidewire 4 is designed to be flexible yet firm enough to push through the obstruction 12. Typically, the user applies a combination of pushing and rotational movements to penetrate the obstruction 12 without dislodging large pieces of the obstruction 12 that could travel downstream and cause an embolism.

[0127] Next, in Figures 11c to 11f, the catheter 43 advances through the obstruction 12. Once the catheter 43 has been inserted into the blood vessel 2, it advances distally over the guidewire 4 and through the obstruction as shown in Figures 11c to 11 f. The guidewire 4 ensures that the catheter 43 follows the correct route within the blood vessel 2, whilst also eliminating the risk of vessel perforation. Similarly to the tip of the guidewire 4, the tip 6 of the catheter 43 can push through obstruction 12, enlarging the pathway created by the guidewire 4. Typically, this process is monitored using fluoroscopy, allowing the user to determine where the catheter 43 is in relation to the obstruction 12 and the vessel walls 2.

[0128] In Figures 11 d and 11e, a therapeutic agent is emitted from the infusion ports 42 disposed at the distal end of the catheter 43. The agent can be emitted as the catheter 43 enters the obstruction 12, advances through the obstruction 12 and exits the obstruction 12. This emission allows the drug to be delivered precisely at the site of the obstruction 12, dispersing into the obstruction 12 to break down the material of the obstruction and hence to restore blood flow.

[0129] In Figure 11g, the guidewire 4 is retracted relative to the distal end of the catheter 43 to prevent the guidewire 4 from being wrapped around the macerator 48 during the thrombectomy procedure. Once the guidewire 4 has been retracted, the macerator 48 is deployed by retracting the outer sheath 8 of the catheter 43 beyond the proximal end of the obstruction 12, as shown in Figures 11 h and 11 i. This allows the macerator 48 to expand radially to its full profile.

[0130] Figure 11j shows the deployed macerator 48 engaged with the obstruction 12. On being retracted proximally towards the distal end of the outer sheath 8, the macerator 48 captures the obstruction 12. The macerator 48 is continuously turned, for example by rotating the macerator 48 alternately clockwise through 180 degrees and anticlockwise through 180 degrees, or by rotating the macerator 48 in one direction, until the macerator 48 has been retracted to the distal end of the outer sheath 8. The rotating macerator 48 squeezes fluid from the obstruction 12, reducing the volume of the obstruction 12 and capturing fibrous material in the process.

[0131] In Figures 11 k and 111, the macerator 48 with the obstruction 12 is either pulled directly into the outer sheath 8, or it is simultaneously pulled and rotated into the outer sheath 8. The pulling action cuts the obstruction 12 into smaller pieces that are suitable for aspiration by the outer sheath 8. The fibrous material trapped between the bristles of the macerator 48 enters the outer sheath 8.

[0132] Next, in Figures 11m to 11 v, any residual obstructions 12 are removed from the blood vessel 2. If deemed necessary, the guidewire 4 is readvanced distally through a residual obstruction 12 as shown in Figure 11n. Next, the catheter 43 also advances through the residual obstruction 12, re-advancing distally over the guidewire 4 as shown in Figure 11o.

[0133] In Figure 11p, the guidewire 4 is retracted relative to the distal end of the catheter 43 to bring the distal end of the guidewire 4 to a proximal position with respect to the proximal end of the macerator 48. Next, the outer sheath 8 of the catheter 43 is retracted beyond a proximal end of the residual obstruction 12, as shown in Figures 11q to 11s. This allows the macerator 48 to deploy and expand radially to its full profile. In Figures 11 r and 11s, the macerator 48 is kept static, providing embolic protection, while the outer sheath 8 is retracted. Aspiration takes place as the outer sheath 8 is retracted until the distal end of the outer sheath 8 is positioned proximally relative to the residual obstruction 12. Manual or automatic aspiration can be applied through the major lumen 38 via a handle 14 port or luer.

[0134] Once the residual obstruction 12 has been aspirated, the macerator 48 returns to its undeployed state by being retracted into the outer sheath 8 as shown in Figure 11t and 11u. The user can repeat these steps to treat the next section in the blood vessel 2 until the blood vessel 2 is clear and blood flow is restored, as shown in Figure 11v. Alternatively, the user can swap the macerator 48 with a macerator 48 of different stiffness or of a different configuration and repeat the above steps.

[0135] In Figure 12, the macerator 48 is shown engaged with the obstruction 12 within the blood vessel 2 and Figure 13 shows channels 54 formed within the obstruction 12 by the action of the macerator 48 after the therapeutic agent has been administered. When removing harder obstructions, the therapeutic agent may be continuously administered in a small, predetermined volume until the macerator 48 is fully deployed. Once deployed, the macerator 48 is manipulated clockwise and anticlockwise while being moved axially forwards and backwards to widen the channels 54 formed by the bristles of the macerator 48. This creates a greater surface area within the obstruction 12 for the blood and the therapeutic agent to interact with, as shown in Figure 13. This macerating motion biases each bristle and forces the bristles deeper into the obstruction 12, allowing deeper penetration of the therapeutic agent.

[0136] As the macerator 48 is held in place to minimise potential vessel flow and to capture the obstruction 12 when loosened, a further small volume of therapeutic agent is then administered. Due to the large surface area presented for interaction between the therapeutic agent and the obstruction 12, the macerator 48 needs to be left in place for a short period of time, typically less than ten minutes, before macerating and removing the obstruction 12 while aspirating as normal.

[0137] Many other variations are possible within the inventive concept. For example, as shown in Figures 14 to 16b, the macerator 48 can have various shapes, lengths and profiles.

[0138] Figures 14a to 14e exemplify variation of bristle length along the length of the macerator 48. The arrangement in Figure 14a is beneficial for embolic protection and captures any residual obstruction as the macerator 48 is retracted into the outer sheath 8. Shorter bristles arranged along the longitudinal centre of the macerator 48 allow for flexibility of the rod 50 and for wrapping an obstruction 12 around and into the macerator 48. The bristle lengths increase progressively toward the proximal and distal ends of the macerator 48, allowing for the obstruction 12 to be macerated and wrapped into the macerator 48.

[0139] Figure 14b exemplifies bristles whose length varies along the length of the macerator 48 in a repeating pattern such as a sine wave, whereas in Figure 14c, the bristles are grouped at the distal and proximal ends of the macerator 48, leaving a longitudinal gap between the groups that allows the rod 50 to have greater flexibility. In Figure 14d, an intermediate group of bristles is disposed between the proximal and distal groups and the groups may vary in terms of bristle lengths and the spacings between them. In Figure 14e, densely-packed bristles grouped at the distal end of the macerator 48 are beneficial for embolic protection whereas the bristles grouped at the proximal end of the macerator 48 are of a different stiffness, for example of a more or less stiff material to allow for a more or less aggressive maceration.

[0140] Figures 15a to 16b demonstrate variation in the pitch of bristles between one macerator 48 and another or along the length of a given macerator 48. The pitch of the bristles refers to the distance between rows or spirals of bristles along the length of the macerator 48. The pitch can significantly affect engagement of the obstruction depending on how densely or sparsely the bristles are arranged.

[0141] In Figure 15a, the pitch is relatively narrow or short as the bristles are closely packed together, resulting in a higher density of bristles along the length of the macerator 48. As this close arrangement increases the number of bristles in contact with the obstruction, the macerator 48 is particularly effective for macerating. Additionally, the close proximity of the bristles to each other makes the macerator 48 stiff, which is useful for macerating harder obstructions such as plaque. In Figure 15b, the narrow pitch of the macerator 48 is shown in the outer sheath in its undeployed state. The narrow pitch of the bristles results in a wider sheath profile as the bristles overlap longitudinally during crimping and hence lie in parallel layers of a radially-layered arrangement. The wider profile allows for a greater amount of the obstruction to be retracted out of the blood vessel 2 as the overlapping can trap more material of the obstruction 12.

[0142] In Figure 16a, the pitch is relatively wide or long as the bristles are spaced further apart along the length of the macerator 48, creating a more open, less dense macerating surface. As fewer bristles come into contact with an obstruction 12, and in turn, the vessel wall 2, the macerator 48 is less abrasive, reducing the risk of mechanical trauma. Moreover, the wider pitch is suitable for engaging soft obstructions 12 as the bristle arrangement allows the obstruction material to lodge between the rows of bristles, making it easier to remove larger portions of the obstruction 12 from a blood vessel 2. Lastly in Figure 16b, the wide pitch of the macerator 48 is shown in the outer sheath in its undeployed state. The wide pitch of the bristles creates a narrow sheath profile as the bristles tend not to overlap during crimping, instead lying in series within a single, common layer. The narrow profile requires less torque than the wider profile, making the macerator 48 easier to rotate during maceration. As brushes can become clogged during maceration, a replacement macerator 48 may become necessary. For instance, during maceration, the more fibrous, or harder obstructions 12 are initially disrupted by the proximal end of the macerator 48. The obstruction 12 is squeezed of fluids and the more fibrous residual obstruction 12 wraps around the proximal end of the macerator 48, leaving the remaining length of macerator 48 void of any fibrous material. Thus, the obstruction 12 tends to build up at this interfacing end and can act like a plug, creating higher catheter retraction forces as unmacerated material of the obstruction 12 is pushed proximally. Such material can override the macerator 48 and remain in the blood vessel 2. More effective removal to reduce the potential clot burden and the number of macerator 48 interchanges can be achieved through the use of a staggered brush profile that allows an increased length of the obstruction 12 to be effectively treated by the one macerator 48.

[0143] Figures 17, 18 and 19 exemplify staggered macerator 60 variations. In Figure 17, the staggered macerator 60 includes one aggressive interface 56, such as prongs, that can penetrate the obstruction 12 and start the wrapping and squeezing process but that is still flexible enough to prevent clinically significant vessel trauma. Alternatively, a staggered macerator 60 with two or more aggressive interface points 56 (as shown in Figure 18 and 19) allows the length of the macerator 60 to be used significantly more effectively.

[0144] As the macerator 60 retracts proximally, the obstruction 12 is initially engaged in smaller portions by relatively aggressive ramp interfaces 56.

[0145] The intermediate brush section 58, that is, the longitudinally central section disposed between each aggressive interface 56, wraps and holds a fibrous obstruction 12. This intermediate section 58 is less aggressive than the ramp interfaces 56 and may have a radially narrower profile. However, the bristles of the intermediate section 58 are densely arranged to spread holding forces and encourage full capture of the obstruction 12, reducing ruptures and breakaways of the obstruction 12. Once the obstruction 12 has been engaged, the intermediate brush section 58 is then used to wrap and hold the remaining more fibrous parts of the obstruction 12. To protect vessel walls from excessive forces, the interfaces 56 and the macerator 60 as a whole are designed to flex during operation.

[0146] Aggressive interfaces 56 and effective capture of a fibrous obstruction 12 promote more effective removal of the obstruction 12 and improved long-term outcomes as the risk of post-thrombotic syndrome and clot recurrence is reduced. Moreover, fewer interchanges of the macerator 60 are required, thus saving time as there are fewer procedural steps which is, in turn, safer for the patient.

[0147] Significantly to increase the efficacy of disrupting the obstruction 12 and to promote wrapping around the intermediate brush section 58, the ramp interfaces 56 can be made more aggressive. For instance, a staggered brush profile 60 with stiffer interfacing bristles can engage, squeeze, hold and macerate the obstruction 12 effectively. The wider the profile of the macerator 60, the lower the stiffness of the brush, so the larger interfaces can be made stiffer again to compensate. The softer bristles of the intermediate section 58 primarily support wrapping of the captured obstruction 12 and may have a reduced, radially narrower profile. Consequently, the macerator 60 is more atraumatic allowing more space for capturing an obstruction 12.

[0148] Figure 20 shows a staggered macerator 60 with dense bristles at each interface 56. Here, the denser bristles provide more aggressive capture of an obstruction 12 for enhanced wrapping.

[0149] In Figures 21 , 22 and 23, a staggered macerator 60 is accompanied by dedicated disruptor components 62 at a proximal side of each interface 56. The disruptors 62 are stiff bar-shaped extrusions, or radially-extending arms for example in a cruciform arrangement, attached to the rod 50 in various configurations. Distal ends of the disruptors 62 can include ball tips 64, 66 as shown in Figure 22 or barbed tips that increase clot capture performance. Alternatively, multiple disruptors such as two or more ball-tipped disruptors 66 can be disposed on the proximal end of the macerator 60 as shown in Figure 23.

[0150] Figures 24a to 24d show expansion of a disruptor 62 in isolation after deployment. The disruptor 62 is deployed in a loaded, radially narrowed configuration within the outer sheath 8 as shown in Figure 24a, where the arms are in a retracted state, generally parallel to the rod 50 of the macerator 60. On being released from the sheath 8, the disruptor 62 partially self-expands as its arms extend radially outwardly at an acute angle from the rod 50 as shown in Figure 24b. This extension enables the arms of the disruptor 62 initially to impale the obstruction 12 on proximal movement of the macerator 60 as shown in Figure 24c. With further pulling and rotation of the macerator 60, the arms of the disruptor 62 extend radially further due to resistance of the obstruction 12 as shown in Figure 24d, ready for effective engagement and maceration of the obstruction 12.

[0151] In Figures 25a to 28b, disruptors 62 are integrated along the length of the macerator 60. In Figures 25a and 25b, the disruptors 62 are integrated within the brush of the macerator 60 on a proximal side of each interface 56. Alternatively, as shown in Figures 26a to 27b, bristles are removed from the brush of the macerator 60 beside the interfaces 56 to accommodate the catheter sheath loading of thicker interface disruptors 68. This reduces the loading forces and hence the risk of damage to the sheath. Additionally, the distal ends of the interface disruptors 68 can be modified to increase the efficiency of capturing an obstruction 12 and / or safety. For example, as illustrated in Figures 28a and 28b, the distal ends of the disruptors 68 can be thermoformed to create atraumatic balls or hooked or flattened ends 70 that snag fibrous material. In another variation, the wrapping brush profile can be shortened to reduce loading forces on the outer sheath 8 while increasing space for capture of extra fibrous obstruction 12 as shown in Figures 29a to 29c. In this respect, the brush of the macerator 60 may have at least some sections in which bristles are relatively long in mutually-opposed angular directions and relatively short in mutually- opposed orthogonal directions.

[0152] Figure 30 exemplifies a multi-macerator configuration 72. By adding one or more macerators 60, optionally with varied interfaces or dimensions, to the rod 50, overall performance in terms of obstruction removal is enhanced and the number of macerator interchanges can be reduced, thus increasing the safety of the procedure. Optionally, a swivel disposed between successive macerators 60 can prevent one of the macerators 60 rotating and so reduce the necessary torque input.

[0153] In another variation, some or all of the interfaces can be replaced by more aggressive machined cutter components 74, 76, 78 as shown in Details B, C and D of Figure 31. Larger-radius cutter components 74, 76 shown in Details B and C, including preformed nitinol tubing, allow radial contraction and expansion of macerator arms during loading and deployment. Conversely, smaller-radius cutter components 78 that are fixed in shape as shown in Detail D can be loaded into a sheath without radial contraction. The component 78 has arms with tapered ends that accommodate re-loading into a sheath while in-body. The cutter components 76, 78 shown in Details C and D comprise circumferentially-facing cutter blades. The cutter component 74 of Detail B comprises a tubular body 80 with a central bore extending to its proximal and distal ends to accommodate the rod 50. The component 74 has two arms 82 that extend outwardly from the body 80 at acute angles to the central longitudinal axis of the body 80. The arms 82 are spaced apart along the length of the body 80 in a staggered arrangement and project in mutually opposed directions relative to the body 80. This arrangement allows for efficient capture of an obstruction 12.

[0154] Similarly to Detail B, the cutter component of Detail C comprises a tubular body 86 with a central bore 90 to accommodate the rod 50. Curved, flexible plates 88 extend outwardly from the body 86 and are arranged in a longitudinally alternating, staggered manner. This provides multiple points of contact and wider coverage for more aggressive capture of an obstruction 12. The gentle curvature of the plates 88 also supports gripping or enclosing an obstruction 12, whereby the obstruction 12 can be securely held between the plates 88 without excessive damage or fragmentation.

[0155] As with Detail B and C, the component 78 of Detail D features curved plates 94 extending outwardly from a tubular body 92 that accommodates the rod 50 in a central bore 96. The plates 94 have a sharp curvature, resembling a hook, which is suitable for cutting up an obstruction 12. In addition, the plates 94 are elongated, extending radially away from the body 92 to provide a large surface area for engaging with the obstruction 12. The symmetrical placement of the plates 94 on opposite sides and ends of the component 78 ensures that the plates 94 apply equal pressure to the obstruction 12.

[0156] Figure 32a shows a macerator 60 with nitinol tubular hub components 100 in a loaded configuration 98. In the loaded configuration 98, while the macerator 60 is positioned in the outer sheath 8, arms 102 of the hub components 100 are in a retracted state, generally parallel to the rod 50. Next, in Figure 32b, the macerator 60 is shown in a deployed configuration 104. In the deployed configuration 104, when the macerator 60 has advanced distally through the outer sheath 8 of the catheter 43 or the sheath 8 has been retracted proximally, the arms 102 of the hub components 100 are fully extended. Once fully extended, the arms 102 cut into an obstruction 12 and initiate the capturing process before wrapping.

[0157] Figures 33 and 34 show a hub component 100 in greater detail. In the loaded configuration 98 shown in Figure 33, the hub component 100 is an open-ended tubular structure with arms 102 extending longitudinally in a retracted position. Conversely, in the deployed configuration 104 shown in Figure 34, the arms 102 of the tube 100 extend radially outwardly to rotate as shown during a maceration procedure.

[0158] Figures 35a to 35I exemplify a process for removing obstructions 12 from a blood vessel 2 using a staggered macerator 60. In Figure 35a, the obstruction 12 is shown in the blood vessel 2. In Figure 35b, a guidewire 4 advances through the obstruction 12. As the guidewire 4 advances through the obstruction 12, the distal tip of the guidewire 4 physically disrupts the structure of the obstruction 12, creating a channel through the obstruction 12.

[0159] Next, in Figures 35c and 35d, the catheter 43 advances distally through the obstruction 12over the guidewire 4. The guidewire 4 is then retracted distally and the staggered macerator 60 is deployed by retracting the outer sheath 8 of the catheter 43 to the proximal side of the obstruction 12, as shown in Figure 35e and Detail E.

[0160] In Figures 35f, 35g and Detail F, the deployed macerator 60 engages with the obstruction 12. On being retracted proximally toward the distal end of the outer sheath 8, the macerator 60 captures the obstruction 12. The macerator 60 is continuously twisted by rotating the macerator 60 until the macerator 60 reaches the distal end of the outer sheath 8. The rotating interfaces of the macerator 60 squeeze fluid from the obstruction 12, reducing the volume of the obstruction 12 and capturing fibrous material of the obstruction 12 in the process.

[0161] Referring now to Figures 35h and 35i, the macerator 60 carrying the obstruction 12 is pulled directly into the outer sheath 8 and the guidewire 4 is readvanced to the original starting point. Next, in Figure 35j, the catheter 43 is readvanced through the blood vessel 2 and the macerator assembly 60 is retracted proximally out of the catheter. Aspiration is then conducted in Figure 35k as the outer sheath 8 is retracted along the full length of the vessel 2.

[0162] Many other variations are possible within the inventive concept. For example, Figures 36a to 40b show variations of the catheter tip 6 and the outer sheath 8. In Figure 36a, the guidewire 4 extends outwardly from the minor lumen 36 of the outer sheath 8 and along a groove 104 offset laterally from a central longitudinal axis of the catheter tip 6. The catheter tip 6 is bonded to the distal end of the rod 50 and is rounded to minimise tissue damage and to provide for smooth guidance through a blood vessel 2. In Figure 36b, the guidewire 4 is retracted, and the outer sheath 8 retracted. This fully exposes the catheter tip 6, a key component within the macerator assembly 20, 60. The macerator assembly 20, 60, is completely independent of the guidewire 4, outer sheath 8 and handle 14. This allows simple exchanges of the macerator assembly 20, 60, both inside and outside the blood vessel, creating a rapid exchange (RX) device.

[0163] In Figures 37a to 38b, the distal end of the outer sheath 8 is tapered into a bevelled edge. The distal end of the catheter tip 6 is also tapered, in the form of a flattened head. This slanted tip 6 reduces the overall contact area between the catheter tip 6 and the blood vessel 2, minimising tissue trauma during navigation as well as ensuring correct relative alignment of the components before readvancement. In Figures 37a and 38a, the guidewire 4 extends outwardly from the minor lumen 36 of the outer sheath 8 and through a longitudinal groove 104 offset laterally from the central longitudinal axis of the catheter tip 6. In Figures 37b and 38b, the guidewire 4 and the outer sheath 8 retracted, akin to Figures 36a and 36b.

[0164] Figures 39a to 40b show further variations of Figures 37a to 38b. In Figures 39a and 39b, the groove 104 of the catheter tip 6 is omitted. Instead, as shown in Figure 39a, the guidewire 4 extends outwardly from the minor lumen 36 of the outer sheath 8, independently of the catheter tip 6. In Figure 39b, the guidewire 4 and the outer sheath 8 is again retracted. The flat, rectangular catheter tip 6 eases cutting into an obstruction 12.

[0165] In Figure 40a, a reinforced inner tube 108 containing the guidewire 4, extends distally through a groove 104 offset laterally from a central longitudinal axis of the catheter tip 6 in axial alignment with the minor lumen 36 of the outer sheath 8. The exposed inner tube 108 physically disrupts the structure of an obstruction 12, creating a small channel or path through the obstruction 12. Again, the catheter tip 6 is rounded to minimise tissue damage and to provide smooth guidance through a blood vessel 2. In Figure 40b, the guidewire 4 and outer sheath 8 are retracted, revealing the macerator assembly 20, 60 and further exposing inner tube 108.

[0166] Figure 41 shows a variation of the catheter assembly 43. In this variation, the outer sheath 8 contains a rod 50 as previously shown in Figures 37b, 38b, 39b, and 40b. The rod 50 reduces clot burden, before the outer sheath 8 is advanced. The distal ends of the outer sheath 8 and of the rod 50 include a catheter tip 6. Each catheter tip 6 includes infusion ports 42 to emit therapeutic or thrombolytic agents directly into the obstruction 12. Referring now to Figures 42a to 44c, a protruding multi-lumen guide wire lumen is shown. These may be regarded as variants of the embodiment shown in Figure 40a and may be used in combination. In this variation, a distally-tapered outer sheath tip 110 exists at the distal end of the outer sheath 8. The tapered tip 110 increases the ease of penetrating an obstruction 12, tracking around vessel curvatures, and provides atraumatic protection. Within the outer sheath 8 there is a minor lumen 112 offset laterally from the central longitudinal axis of the outer sheath 8. The minor lumen 112 accommodates the guidewire 4, which extends from the minor lumen 112 to protrude distally from the sheath tip 110. An encapsulated reinforcement tube may extend from the minor lumen 114 to enhance the bond between the outer sheath tip 100 and the outer sheath 8, enhance pushability through a blockage, and may be radiopaque, further enhancing ease of use as visibility is improved under fluoroscopy.

[0167] In a further variation, the tapered other sheath tip 110 includes an enlarged head 116 in the form of a low durometer tube, as shown in Figures 43a and 43b. The tube 116 is offset laterally from the central longitudinal axis of the outer sheath 8. This arrangement further promotes pushability through an obstruction 12 and provides atraumatic protection without affecting the outer sheath profile. The tube 116 is contained within a bevelled section of the distal end of the outer sheath 8 and as such, the internal diameter of the outer sheath 8 is not impacted. The bevelled opening allows the guidewire 4 to be retracted smoothly into the outer sheath 8 for controlled deployment, ensuring that the transition between the guidewire 4 and the outer sheath 8 is streamlined and non-traumatic. The tube 116 is flexible enough to allow a macerator 48 to enter and exit the outer sheath 8 and can also be radiopaque. The distal end of the other sheath 8 can also include infusion ports 42 that face radially outwardly to emit therapeutic or thrombolytic agents directly into the obstruction 12.

[0168] Figures 44a to 44d illustrate a variety of operational configurations of a staggered macerator 118 as it engages an obstruction 12 or clot. These configurations are particularly advantageous for capturing and removing fibrous mesh-like structures within the obstruction 12, thereby facilitating aspiration of the remaining clot material.

[0169] Figure 44a shows the staggered macerator 118 in a deployed state 122. The outer sheath 8 of the catheter has been retracted allowing the staggered bristles to extend outwardly and proximally at an acute angle relative to the longitudinal axis of the rod 50. The angular orientation results from the combination of bristle material properties (e.g., plastically deformable) and the pitch imparted to the bristles by twisting the wires 119 together about the longitudinal axis. Once the macerator 118 is released from the outer sheath 8, the bristles remain at a relatively shallow angle relative to the longitudinal axis of the rod 50, ready to engage material of the obstruction 12 when the macerator 118 is moved proximally.

[0170] Figure 44b illustrates the staggered macerator 118 in a locked-in configuration 124. Here, the macerator 118 is initially retracted proximally through the obstruction 12, typically by approximately 10 to 20mm, toward the distal end of the outer sheath 8. This proximal translation through the obstruction 12 creates resistance that causes the bristles to deflect to a greater angle relative to the longitudinal axis of the rod 50. Thus, the bristles are driven radially outwardly as they engage with the obstruction 12, enabling them to impale and embed deeper into the fibrous mesh-like structures of the obstruction 12. This configuration enhances the ability of the macerator 118 to grip and collect material of the obstruction for subsequent removal.

[0171] Figure 44c illustrates the staggered macerator 118 in a snag-and collect configuration 126. Here, the macerator 118 is actively manipulated by rotating clockwise and / or anticlockwise about the longitudinal axis of the rod 50. As the bristles of the macerator 118 embed further into the obstruction 12, continued manipulation causes the fibrous mesh-like structures of the obstruction 12 to wrap around the bristles. To promote further impalement, the macerator 118 can be rotated in opposite angular directions to a greater angular extent, for example through 180°. This back-and-forth movement squeezes out fluid from the obstruction 12 and enables more of the residual fibrous material to be wrapped around the macerator 118. The macerator 118 is then either retracted directly into the outer sheath 8, or simultaneously pulled and rotated into the outer sheath 8, causing the more fibrous material trapped between the bristles of the macerator 118 to enter the outer sheath 8.

[0172] As the macerator 118 is drawn into the sheath 8, the distal end of the sheath 8 serves as a cutting interface, further fragmenting the obstruction 12 into smaller pieces more suitable for aspiration.

[0173] When significant fibrous material has been removed or disrupted by the agitating movement of the macerator 118, the residual clot is easier to aspirate. In this respect, Figure 44d shows the macerator 118 in a removal configuration 128, wherein the macerator 118 is first retracted into the outer sheath 8 and then completely removed from the device 10. The piston effect of this retraction movement acts as an aspirator as the macerator 118 creates a reduced pressure or vacuum that is sufficient to pull in fragmented and loosened material of the obstruction 12 into the outer sheath 8.

[0174] Figures 45a and 45b are further views of the staggered macerator 118 in its deployed state 122, corresponding to Figure 44a.

[0175] In Figure 45a, the outer sheath 8 has been proximally retracted to expose the macerator 118. The bristles of the macerator 118 are arranged in a staggered formation around the central axis of the rod 50. Specifically, the bristles vary in length along the rod 50, with the bristles increasing in length toward the distal end of the macerator 118. More specifically, the lengths of the bristles increase in a stepwise manner from one group of bristles to the next in longitudinal series. This tapered design allows the macerator 118 to treat a longer segment of the obstruction 12, shown here in a cross-section, more effectively while maintaining a compact profile suitable for delivery through narrow blood vessels 2.

[0176] The stepwise variation in length of the bristle also enables different portions of the obstruction 12 to be targeted by different groups of bristles along the length of the macerator 118. Specifically, successively enlarged groups of bristles successively engage radially wider portions of the obstruction 12 as the macerator 118 moves proximally through the obstruction 12.

[0177] The bristles are preferably made from a plastically deformable or shape-retaining material that enables them to remain splayed outwardly once deployed from the outer sheath 8. In other words, the bristles have a preliminary set that biases them into the aforementioned acute angle relative to the longitudinal axis of the rod 50. This ensures consistent contact with the obstruction 12 throughout the procedure.

[0178] Figure 45b also shows the macerator 118 in the deployed configuration 122. This isolated view highlights the staggered bristle arrangement along the rod 50. The bristles are staggered about the twisted wires 119 of the rod 50, creating a dense, brush-like structure that maximises contact with the obstruction 12 and wrapping of fibrous strands of the obstruction 12 during rotation of the macerator 118. Figures 46a and 46b show the macerator 118 in the locked-in configuration 124 also shown in Figure 44b.

[0179] In Figure 46a, the macerator 118 is retracted proximally. This causes the bristles to extend radially outwardly from the rod 50 to impale material of the obstruction 12 more deeply, as retraction drives the bristles into the mass of the obstruction 12. This enables more effective anchoring and disruption of the more fibrous material of the obstruction 12 along the length of the macerator 118.

[0180] Figure 46b shows the bristles of the macerator 118 further extended to a greater angle relative to the longitudinal axis of the rod 50. Indeed, in this example, the bristles lie in respective longitudinally-spaced planes that are substantially orthogonal to the longitudinal axis of the rod 50.

[0181] The perspective view of Figure 46c shows the macerator 118 in the locked-in configuration 124 also shown in Figures 46a and 46b.

[0182] Figures 47a and 47b illustrate a variation of the macerator 130 featuring a bristle arrangement in which the lengths of the bristles increase progressively in the distal direction. Thus, the macerator 130 has a proximally-tapering brush profile, with longer bristles at the distal end of the rod 50 and shorter bristles toward the proximal end of the rod 50.

[0183] Figure 47a shows the macerator 130 in its deployed configuration 122 in which the bristles are at a relatively small acute angle to the longitudinal axis of the rod 50, whereas Figure 47b shows the macerator 130 in a locked-in configuration 124 in which the bristles are at a relatively large angle to the longitudinal axis of the rod 50.

[0184] As previously, when the macerator 130 is in the locked-in configuration 124 shown in Figure 47b, proximal retraction causes the bristles to drive outwardly, embedding deeper into an obstruction 12.

[0185] If the macerator 130 is deployed distally to the obstruction 12, the shorter proximal bristles engage the obstruction 12 first. As retraction continues, the longer distal bristles follow suit, resulting in progressively greater engagement along the length of the obstruction 12. This promotes disruption and effective collection of material of the obstruction 12 for subsequent removal. However, if the macerator 130 is deployed within the obstruction, the shorter proximal bristles and longer distal bristles engage with the obstruction at the same time.

[0186] Figures 48a and 48b illustrate the snag-and collect configuration 126 of the macerator 118 as also shown in Figure 44c. This configuration is designed to promote progressive impalement and wrapping of fibrous obstructive material within a blood vessel 2.

[0187] As the macerator 118 is retracted proximally, a plunger-like effect is generated. This pulling motion compresses the obstruction 12, driving its fibrous material into the stepped spaces 132 around successive groups of bristles and facilitating more effective impalement by the bristles. This mechanism facilitates treatment of different zones of the obstruction 12.

[0188] Simultaneously or sequentially, the macerator 118 may be rotated, initiating a gentle wrapping motion, causing the bristles to ensnare the fibrous mesh-like structures of the obstruction 12. This promotes intact capture of then fibrous material. As wrapping continues, the fibrous material is drawn toward the rod 50 of the macerator 118, creating additional space for further clot capture and entanglement. Non-fibrous components of the obstruction 12 are compressed during this wrapping and pulling action, squeezing liquid out of the obstruction 12.

[0189] Together, the agitation of combined retraction and rotation causes dual-phase operation of the macerator 118, namely: impalement and compression of the obstruction 12 via longitudinal plunger action; and wrapping and consolidation of fibrous elements of the obstruction 12 toward the rod 50. The snag-and-collect configuration 126 significantly minimises the number of required passes of the macerator 118 through a blood vessel 2, increasing efficiency and minimising trauma to the vessel wall.

[0190] Figures 49a to 49m exemplify a process for removing an obstruction 12 from a blood vessel 2 using a staggered macerator 118.

[0191] In Figure 49a, the obstruction is shown in the blood vessel 2. In Figure 49b, a guidewire 4 has been advanced through the obstruction 12. As the guidewire 4 advances through the obstruction 12, the distal tip of the guidewire 4 disrupts the structure of the obstruction 12, creating a channel through the obstruction 12. Turning to Figure 49c, a catheter dilator 134 has been advanced distally through the obstruction 12 over the guidewire 4. The dilator 134 enlarges the channel of the obstruction 12 to allow for insertion of an outer sheath 8, also shown in Figure 49c having been advanced distally through the obstruction 12.

[0192] The guidewire 4 and dilator 134 are then retracted proximally, until removed fully from the device, leaving the distal end of the outer sheath 8 protruding distally from the distal end of the obstruction 12 as shown in Figure 49d. In Figure 49e, the macerator 118 is advanced distally through the outer sheath 8 until a tip 120 of the macerator 118 is positioned distally beyond the obstruction 12.

[0193] Next, the macerator 118 is deployed by retracting the outer sheath 8 of the catheter proximally through the obstruction 12 as shown in Figure 49f. As the outer sheath 8 is retracted, the bristles of the macerator 118 extend radially outwardly and proximally at an acute angle relative to the longitudinal axis of the rod 50 of the macerator 118, ready to engage with the obstruction 12.

[0194] Turning to Figure 49g, the macerator 118 is then rapidly retracted, for example by approximately 10 to 20mm, to initiate engagement of the bristles with the obstruction 12. The sudden retraction movement causes the bristles to flare outwardly relative to the rod 50 to impale and lodge in material of the obstruction 12.

[0195] In Figure 49h, the macerator 118 is slowly retracted and rotated to promote further impalement of the obstruction 12. At any stage, the macerator 118 can be rotated to a greater angular extent, for example through 180°. This rotational movement assists in expelling fluid from the obstruction 12 and enables more of the residual fibrous mesh to be impaled and wrapped around the macerator 118.

[0196] The macerator 118 is then retracted proximally toward the distal end of the outer sheath 8. Rotation of the macerator 118 can continue until the macerator 118 reaches the distal end of the outer sheath 8 as shown in Figure 49i.

[0197] Next, as shown in Figure 49j, the macerator 118 is gradually retracted into the distal end of the outer sheath 8. As this occurs, any residual obstruction 12 material is cut with the distal end of the outer sheath 8 serving as the cutting interface, cutting material of the obstruction 12 into smaller fragments suitable for aspiration. In this respect, it will be noted that the distal end of the outer sheath 8 is inclined relative to its central longitudinal axis to aid the cutting action and later aspiration.

[0198] Once the macerator 118 is fully withdrawn into the outer sheath 8, the macerator 118 is then rapidly retracted proximally until it is fully removed from the device 10. The piston action generated by this rapid motion facilitates aspiration of any residual clot material 12 through the outer sheath 8, as shown in Figure 49k, ensuring that loose or fragmented debris is removed from the blood vessel 2. The macerated thrombus can be further aspirated using a separate device, like a manual syringe or vacuum pump, possibly connected to the handle.

[0199] Figure 49I shows the outer sheath 8 remaining in situ during optional intravascular imaging to confirm that blood can flow freely through the blood vessel 2.

[0200] In Figure 49m, the outer sheath 8 is withdrawn from the blood vessel 2, thus completing the procedure.

[0201] Figures 50a to 52e show variants of a staggered macerator 118 with various trimmed or locally shortened bristle configurations, each illustrated in the locked-in configuration 124. In all of these variants, the outer ends of some bristles are trimmed, cut or otherwise shortened relative to other bristles, optionally along the full length of the macerator as shown. The result in each case is an end-on profile that varies in diameter moving around a central longitudinal axis defined in this case by a twisted wire 119. An effect of this is to lower sheathing and deployment forces and to permit passage through a smaller delivery sheath. Regions with shorter bristles 136 also define recessed zones 140 of lesser diameter extending along the macerator 118, which provide additional space for wrapping the fibrous material of a clot during rotation of the macerator 118. Consequently, the combination of longer 138 and shorter bristles 136 moving circumferentially around the wire 119 enhances snagging of the fibrous material.

[0202] Figures 50a to 50e illustrate a macerator 118 in its locked-in configuration 124, showing the bristles projecting outwardly from the wire 119. As best appreciated from the end view of Figure 50c, the bristles comprise longer bristles 138 in groups diametrically opposed about the wire 119 and shorter bristles 136 in groups also diametrically opposed about the wire 119, the groups of the shorter bristles 136 extending orthogonally between the groups of the longer bristles 138. Consequently, the groups of longer bristles 138 alternate circumferentially with the groups of shorter bristles 136.

[0203] In the orientation shown in Figure 50c, the longer bristles 138 are grouped above and below the wire 119, and the shorter bristles 136 are grouped to respective sides of the wire 119. In this example, the bristles collectively define a stadium-like profile in end view, that profile having curved portions corresponding to the groups of longer bristles 138 and substantially parallel straight sides corresponding to the groups of shorter bristles 136.

[0204] As best shown further in Figures 50a, 50d and 50e, the bristles define a longitudinal taper, wherein the macerator profile gradually narrows from the distal end, shown to the left in these figures, toward the proximal end of the macerator 118, shown to the right in these figures. These views also illustrate the staggered bristle profile in which successive stepwise reductions in bristle length form recessed capture zones 140 along the length of the macerator 118. Each capture zone 140 engages and retains portions of fibrous material of a clot as the macerator 118 is retracted.

[0205] A comparison of Figures 50d and 50e shows that all of the bristles, both the longer bristles 138 and the shorter bristles 136, shorten in length moving proximally along the macerator 118.

[0206] Figures 51a to 51 e illustrate a further variant of the macerator 118 in its locked-in configuration 124. In this embodiment, as best appreciated in Figures 51d and 51e, only the longer bristles 138 exhibit tapering, decreasing in length in a stepwise manner in the proximal direction along the macerator 118, while the shorter bristles 136 to the sides remain substantially uniform in length along the length of the macerator 118. Thus, as shown in Figure 51 d, the shorter bristles 136 are trimmed along substantially straight, parallel planes extending along the macerator 118.

[0207] Figures 52a to 52e illustrate a further variant of the macerator 118 in its locked-in configuration 124. In this embodiment, the bristles alternate between longer 138 and shorter lengths 136 around the circumference of the wire 119. This circumferentially alternating or staggered arrangement reduces overall bulk of the macerator 118 while creating multiple capture zones 140 for engagement and maceration of the obstruction. As can be seen in Figures 52b and 52c, the longer bristles 138 extend outwardly in groups diametrically opposed about the wire 119, and the shorter bristles 136 are arranged orthogonally between those groups. In this configuration, the tips of the bristles collectively define a circumferentially stepped outer contour that provides recessed portions 142 between the longer 138 and shorter bristles 136. The recessed portions 142 created by this alternating stepped arrangement creates multiple longitudinal channels for capturing and retaining fibrous material.

[0208] Figures 52a, 52d, and 52e illustrate a stepped configuration along the length of the macerator 118. In this embodiment, the bristles are gathered into a series of longitudinally-extending groups. In some of those groups, longer bristles 138 and shorter bristles 136 extend from the wire 119 in mutually orthogonal relation. Some of those groups containing longer 138 and shorter bristles 136 are rotated relative to each other. In others of those groups, bristles are of substantially equal length around the full circumference of the macerator. The alternating bristle lengths create variations in diameter along the length and around the circumference of the macerator 118, defining multiple recessed capture zones 140, 142.

[0209] Figures 53a and 53b illustrate another variant of a staggered macerator 118 in a deployed configuration 104. In this variant, the bristles are arranged along the wire 119 in alternating longitudinal zones of differing bristle density and stiffness. More specifically, groups of densely packed bristles 144 alternate with groups of more widely spaced bristles 146. Each group of densely packed bristles 144 is on a proximal side of a respective group of widely spaced bristles 146.

[0210] Bristles of the densely packed groups 144 preferably have reduced stiffness, allowing them to flex more readily than the more widely spaced bristles 146 of the other groups. This combination of higher density and lower stiffness increases surface contact and promotes wrapping of the fibrous material around the macerator 118. Conversely, the stiff bristles 146 of the intermediate groups are less tightly packed but resist deflection, making them well-suited to impale and penetrate fibrous obstructions.

[0211] In the deployed configuration 104 shown here, the outer sheath of the catheter has been retracted. Initially, the relatively stiff and more widely spaced bristles 146 extend outwardly and proximally at an acute angle relative to the longitudinal axis of the wire 119. As the bristles are at a relatively shallow angle relative to the longitudinal axis of the wire 119, they are oriented to engage material of the obstruction when the macerator 118 is moved proximally. Conversely, the more densely packed and more flexible bristles 144 of the groups project outwardly in planes orthogonal to the longitudinal axis of the wire 119 to maximise surface contact and wrapping.

[0212] Figures 54a and 54b illustrate the macerator 118 of Figures 53a and 53b in a locked-in configuration 124 representing the macerator 118 having been retracted proximally through the obstruction. In that case, the stiff bristle groups 146 engage with the clot, puncturing and anchoring into the fibrous material, before the respective distally adjacent groups of denser, more flexible bristles 144 expand within the obstruction to promote wrapping.

[0213] As previously, proximal retraction of the macerator 118 through an obstruction encounters resistance that forces the stiffer, widely spaced bristles to deflect outwardly to a greater angle relative to the longitudinal axis of the wire. The combination of impalement by the stiffer bristles 146 and wrapping by the flexible bristles 144 enhances anchoring of the obstruction during rotation and withdrawal.

Claims

Claims1. An endovascular thrombus macerator comprising: a central rod; and flexible bristles extending radially from the rod at respective longitudinal positions along the rod; wherein the bristles vary in their radial extent from the rod, and hence length, in accordance with their longitudinal positions along the rod.

2. The macerator of Claim 1 , wherein the length of the bristles varies continuously in a longitudinal direction along the rod.

3. The macerator of Claim 1 or Claim 2, wherein the length of the bristles varies stepwise in a longitudinal direction along the rod.

4. The macerator of any preceding claim, wherein the bristles are grouped into two or more groups disposed in longitudinal succession along the rod.

5. The macerator of Claim 4, wherein the bristles of one of the groups have a first length and the bristles of another of the groups have a second length, being different from the first length.

6. The macerator of Claim 5, wherein the bristles of a distal one of the groups have a greater length than the bristles of a proximal one of the groups.

7. The macerator of any Claims 4 to 6, wherein the groups are spaced apart along the rod in longitudinal succession.

8. The macerator of any of Claims 4 to 7, wherein the bristles at an end of at least one of the groups are stiffer and / or more densely packed than the bristles within a body of that group.

9. The macerator of Claim 8, wherein the stiffer or more densely packed bristles are disposed at a junction between successive groups.

10. The macerator of any preceding claim, wherein distally disposed bristles are stiffer or more densely packed than proximally disposed bristles.

11. The macerator of any preceding claim, wherein the bristles are deformable or deflectable.

12. The macerator of any preceding claim, wherein the bristles extend radially outwardly and proximally at an acute angle relative to a longitudinal axis of the rod.

13. The macerator of Claim 12 when dependent on Claim 11, wherein the bristles are deflectable from an initial position at a lesser angle to the longitudinal axis of the rod to an extended position at a greater angle to the longitudinal axis of the rod.

14. The macerator of any preceding claim, further comprising at least one disruptor extending radially from the rod, the or each disruptor being substantially rigid.

15. The macerator of Claim 14, wherein the or each disruptor has substantially the same radial extent from the rod, and hence length, as adjoining bristles.

16. The macerator of Claim 14 or Claim 15, wherein the or each disruptor comprises radially extending arms.

17. The macerator of Claim 16, wherein the arms are substantially straight.

18. The macerator of Claim 16, wherein the arms are curved.

19. The macerator of Claim 18, wherein the arms are curved about longitudinal axes.

20. The macerator of any of Claims 16 to 19, wherein the arms are in cruciform relation.

21. The macerator of any of Claims 16 to 20, wherein the arms are pivotable relative to the rod.

22. The macerator of any of Claims 16 to 21 , wherein the arms have bulbous radially outer ends.

23. The macerator of any of Claims 15 to 21 , wherein the arms have hooked radially outer ends.

24. The macerator of any of Claims 14 to 23, comprising at least two of the disruptors in mutually adjacent longitudinal succession.

25. The macerator of Claim 24 when dependent on any of Claims 16 to 23, wherein the mutually adjacent disruptors have arms that are angularly offset from each other about the rod.

26. The macerator of any of Claims 14 to 26 when dependent on any of Claims 4 to 9, wherein the or each disruptor is disposed within a respective group of the bristles.

27. The macerator of Claim 26, wherein the or each disruptor is offset toward an end of the respective group of the bristles.

28. The macerator of any of Claims 14 to 26 when dependent on Claim 7, wherein the or each disruptor is disposed between the successive groups of the bristles in a space between those groups.

29. The macerator of any of Claims 14 to 28, comprising distally disposed disruptors and proximally disposed disruptors, wherein the distally disposed disruptors are of greater length than the proximally disposed disruptors.

30. The macerator of any preceding claim, comprising distally disposed bristles and proximally disposed bristles, wherein the distally disposed bristles are of greater length than the proximally disposed bristles.

31. The macerator of any preceding claim, wherein the bristles are arranged helically along the rod.

32. The macerator of any preceding claim, wherein the bristles are arranged in loops around the rod, the bristles of each loop being of substantially constant length from the rod.

33. The macerator of any of Claims 1 to 31, wherein the bristles are arranged in loops around the rod, the bristles of each loop being of varying length from the rod.

34. The macerator of any preceding claim, wherein the rod comprises wires twisted together about a longitudinal axis.

35. The macerator of Claim 4 or any of Claims 5 to 34 when dependent on Claim 4, wherein the bristles of at least one of the groups are more densely packed than the bristles of another of the groups.

36. The macerator of Claim 35, wherein groups with more densely-packed bristles alternate longitudinally along the macerator with groups having less densely-packed bristles.

37. The macerator of Claim 35 or Claim 36, wherein the more densely-packed bristles are less stiff than the less densely-packed bristles.

38. The macerator of any preceding claim, wherein the bristles vary in their radial extent around the circumference of the rod.

39. An endovascular macerator comprising: a central rod; and flexible bristles extending radially from the rod at respective longitudinal positions along the rod; wherein the bristles are grouped into two or more groups disposed in longitudinal succession and spaced apart along the rod.

40. The macerator of Claim 39, wherein the groups are spaced apart along the rod in longitudinal succession.

41. The macerator of Claim 40, wherein the bristles of one of the groups are stiffer than the bristles of another of the groups.

42. The macerator of Claim 41 , wherein the bristles of a distal one of the groups are stiffer than the bristles of a proximal one of the groups.

43. A method of macerating a thrombus, the method comprising: deploying a macerator that comprises bristles extending radially and proximally at acute angles to a longitudinal axis, wherein the bristles vary in length in accordance with their longitudinal positions along the axis, proximal bristles being shorter than distal bristles; and drawing the macerator proximally through the thrombus to engage material of the thrombus by deflecting the bristles from initial positions at a lesser angle to the longitudinal axis to extended positions at a greater angle to the longitudinal axis.

44. The method of Claim 43, comprising engaging a radially inner portion of the thrombus with the proximal bristles and subsequently engaging a radially outer portion of the thrombus with the distal bristles during proximal movement of the macerator through the thrombus.

45. The method of Claim 43 or Claim 44, comprising turning the macerator about the longitudinal axis.

46. The method of Claim 45, comprising wrapping the thrombus material around the bristles.

47. The method of Claim 45 or Claim 46, comprising turning the macerator alternately in opposite angular directions.

48. The method of any Claims 43 to 47, comprising deploying the macerator at least partially within the thrombus.

49. The method of Claim 48, comprising engaging the thrombus material with the proximal bristles and the distal bristles simultaneously when drawing the macerator proximally through the thrombus.

50. The method of any Claims 43 to 47, comprising deploying the macerator distally with respect to the thrombus.

51. The method of Claim 50, comprising engaging the thrombus material initially with the proximal bristles and subsequently with the distal bristles when drawing the macerator proximally through the thrombus.

52. The method of any of Claims 43 to 51 , comprising chopping the thrombus material with at least one rigid disruptor of the macerator.

53. The method of any of Claims 43 to 52, followed by drawing the macerator, carrying the thrombus material, proximally into a sheath.

54. The method of Claim 53, comprising cutting thrombus material with a distal end of the sheath.

55. The method of Claim 53 or 54, comprising withdrawing the macerator, carrying the thrombus material, from a proximal end of the sheath.

56. The method of any of Claims 53 to 55, comprising aspirating macerated thrombus material through the sheath.

57. The method of Claim 56, comprising generating an aspirating flow by withdrawing the macerator, carrying the thrombus material, proximally along the sheath.

58. The method of any of Claims 53 to 57, further comprising: advancing the sheath distally through a residual thrombus; redeploying the macerator from the sheath to engage the residual thrombus; applying aspiration through the sheath; anddrawing the macerator proximally to capture the residual thrombus and to draw the residual thrombus into the sheath.

59. The method of any of Claims 53 to 57, further comprising: advancing the sheath distally through a residual thrombus; deploying a secondary macerator from the sheath to engage the residual thrombus; applying aspiration through the sheath; and drawing the secondary macerator proximally to capture the residual thrombus and to draw the residual thrombus into the sheath.

60. The method of any of Claims 43 to 59, comprising engaging the thrombus material initially with relatively stiff bristles and subsequently with more flexible bristles.

61. A method of performing a thrombectomy, the method comprising: advancing an endovascular guidewire distally across a thrombus to bring a distal end of the guidewire to a distal side of the thrombus; advancing a catheter distally along the guidewire, the catheter comprising a distal tip and an outer sheath containing a major lumen that confines a macerator in a radially-contracted state and a minor lumen along which the guidewire extends, the minor lumen being offset laterally from the major lumen; withdrawing the guidewire proximally through the distal tip of the catheter and along the minor lumen to bring the distal end of the guidewire to a proximal side of the macerator; deploying the macerator from within the catheter into a radially-expanded state by withdrawing the outer sheath proximally relative to the macerator;engaging the thrombus with the macerator; and withdrawing the macerator proximally while removing the thrombus.

62. The method of Claim 61, comprising expelling a thrombolyic agent from the catheter and into the thrombus.

63. The method of Claim 61 or Claim 62, comprising deploying the macerator on the distal side of or within the thrombus before withdrawing the macerator proximally into engagement with the thrombus.

64. The method of any of Claims 61 to 63, comprising withdrawing the macerator and the thrombus through an evacuation channel in a handle of the catheter at a proximal end of the outer sheath, the evacuation channel being coaxial with and communicating with the major lumen of the catheter.

65. The method of Claim 64, comprising removing the macerator and the thrombus through a proximal valve that seals the evacuation channel.

66. The method of Claim 64 or Claim 65, comprising moving the guidewire proximally along a guidewire channel of the handle while withdrawing the guidewire along the minor lumen of the catheter, the guidewire channel being coaxial with and communicating with the minor lumen.

67. The method of Claim 66, comprising removing the guidewire through a proximal valve that seals the guidewire channel.

68. The method of any of Claims 61 to 67, comprising moving the distal end of the guidewire laterally during continued proximal movement of the guidewire after the distal end of the guidewire has been withdrawn through the distal tip of the catheter.

69. The method of Claim 68, comprising aligning the distal end of the guidewire with a central longitudinal axis of the catheter upon passing through the distal tip of the catheter and moving laterally away from the central longitudinal axis toward alignment with the minor lumen with continued proximal movement of the guidewire.

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