Abstract
A thrombectomy device includes a handle at a proximal end portion of the device, a first arm connected to the handle, and a second arm extending to a distal end portion of the device. The device may also include a cage at the distal end portion of the device, the cage being adjustable between a contracted orientation and an expanded orientation, the cage including a cutting element disposed between a proximal end portion of the cage and a distal end of the cage, the cutting element including one or more of a round wire, a flat wire, or a blade configured to remove matter from a body lumen when the cage is in the expanded orientation, and a macerator extending within the first arm and the second arm, the macerator including a helical element.
Claims
1. An extraction device, comprising: a handle at a proximal end portion of the device; a tubular first arm having a window extending radially within a side wall of the first tubular arm; a second arm extending to a distal end portion of the device; a cage at the distal end portion of the device, the cage being adjustable between a contracted orientation and an expanded orientation, the cage including a cutting element disposed between a proximal end portion of the cage and a distal end of the cage, the cutting element including one or more of a round wire, a flat wire, or a blade configured to remove matter from a body lumen when the cage is in the expanded orientation; a macerator extending within the first arm and around the second arm, the macerator including a helical element at least partially exposed through the window; and wherein the cage surrounds a portion of the first arm including the window.
2. The device of claim 1, wherein the helical element surrounds a third arm.
3. The device of claim 2, wherein the third arm is configured to rotate with respect to the first arm and the second arm.
4. The device of claim 1, wherein the macerator includes a cutting edge.
5. The device of claim 1, wherein a pitch of the helical element changes along a length of the macerator.
6. The device of claim 1, wherein the second arm includes a filter configured to allow fluid to exit the macerator.
7. An extraction device, comprising: a proximal end portion; a distal end portion; a proximal tube having a side wall with a window extending through the side wall from an interior of the proximal tube to an exterior of the proximal tube; a radially-expandable cage connected to the proximal tube and extending to the distal end portion, the cage including struts forming a plurality of proximal openings and a plurality of distal openings, at least one of the proximal openings being larger than at least one of the distal openings; a cutting element including one or more of a round wire, a flat wire, or a blade disposed at a widest portion of the cage, the cutting element being configured to remove matter from a body lumen by applying a shearing force; and a maceration device having a surface for removing matter scraped from the body lumen by the cutting element, the maceration device being rotatable with respect to the cage and the proximal tube and in communication with the exterior of the proximal tube through the window within the radially-expandable cage.
8. The device of claim 7, further including a sheath surrounding at least a portion of the proximal tube.
9. The device of claim 7, wherein the maceration device includes a cutting edge on a helical formation of the maceration device.
10. The device of claim 7, further including a distal tube, wherein the maceration device includes a portion that extends within the distal tube.
11. The device of claim 7, wherein the maceration device includes a helical formation extending within the proximal tube.
12. An extraction device, comprising: a proximal end portion; a distal end portion; a proximal tube having a window extending radially from an interior to an exterior of the proximal tube; a radially-expandable cage connected to the proximal tube and extending to the distal end portion, the cage including struts forming a plurality of proximal openings and a plurality of distal openings, at least one of the proximal openings being larger than at least one of the distal openings; a scraping element disposed at the cage, the scraping element being configured to remove matter from a body lumen when the cage is in an expanded orientation; and a maceration device for removing matter removed from the body lumen, the maceration device rotatable with respect to the cage and the proximal tube, and the macerator at least partially exposed through the window and in communication with the exterior of the proximal tube within the radially-expandable cage.
13. The device of claim 12, wherein the proximal openings are defined by a plurality of wires that form the struts.
14. The device of claim 13, wherein the wires that define the proximal openings are twisted together, forming twisted wires.
15. The device of claim 14, wherein the twisted wires include first portions that define the proximal openings and second portions that define the distal openings, the second portions being less tightly twisted as compared to the first portions, and the scraping element is formed at an intersection of the first and second portions.
16. The device of claim 13, wherein a helical formation of the maceration device extends beyond a distal end of the proximal tube.
17. The device of claim 16, wherein the maceration device includes a tube that extends distally of the helical formation.
18. The device of claim 17, wherein a pitch of the helical formation changes over a length of the maceration device.
Description
BRIEF DESCRIPTION OF THE FIGURES
(1) The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, in which:
(2) FIG. 1. Shows a braided cage in its expanded configuration, with a filtered end (201) and an open end (202).
(3) FIG. 2. An example of a cage made from laser cut Nitinol. The distal side is solid tube and the proximal side is a closed mesh to fit over the proximal arm tube.
(4) FIG. 3. An example of a laser cut cage after expansion. The circumferential elements act as filter and separate the thrombus from the vessel wall.
(5) FIG. 4. Cage with cutting element external to the cage.
(6) FIG. 5. Cage with cutting element internal to the cage.
(7) FIG. 6. Cage with cutting element as part of the cage.
(8) FIG. 7. The perimeter of the cage may be tapered at an angle.
(9) FIGS. 8A and 8B. Schematic of the cage and control mechanism, operated using a friction screw.
(10) FIG. 9. Schematic of the cage and control mechanism, operated using a friction screw.
(11) FIG. 10. Schematic of the cage and control mechanism, operated using a friction screw and a spring.
(12) FIGS. 11A and 11B. Schematic of the cage and control mechanism, operated using a spring, and a movable stop.
(13) FIG. 12. Schematic of the cage and control mechanism, operated using a flat spring.
(14) FIG. 13. Schematic of the cage and control mechanism, operated using a flat spring.
(15) FIG. 14. Schematic of the control mechanism, operated using a flat spring.
(16) FIG. 15. The extractor is made of a wire wrapped around a tube. It transports and macerates the thrombus.
(17) FIG. 16. The wire may be displaced above the tube surface.
(18) FIG. 17. The proximal arm may act as the outer tube of the extraction mechanism and provide a passage way to let material from the blood vessel into the lumen of the macerator.
(19) FIGS. 18A and 18B. The proximal arm of extractor with cutting edge and larger extraction path.
(20) FIGS. 19A and 19B. The proximal arm of extractor may have more than one leading edge.
(21) FIG. 20. Image of the macerator with a rotating tip/cutting edge. The tip rotates with the helical formation.
(22) FIG. 21. Shows the cage in its open configuration. The passageway provided by the proximal arm, may be located inside the cage.
(23) FIG. 22. The extractor may be eccentric to the centreline of the cage.
(24) FIG. 23. The tip of the extractor may be eccentric and positioned away from the centreline of the cage.
(25) FIG. 24. Section view—the extractor may contain a region with a shorter pitch. This may compress the debris being extracted and allow fluid to flow back through the cavities and into the vessel.
(26) FIG. 25. Section view—Combination of the cage and the extractor. The cage is opened and closed by the relative movement of the proximal and distal arms. The rotating extractor rotates over the distal arm and within the proximal arm. A sheath can run over the device to ensure the cage is closed during delivery and retrieval.
(27) FIG. 26. Section view—The distal end of the device showing an embodiment of the cage with the extractor tube acting also as the distal arm. As the distal arm moves proximally, the cage opens. As the distal arm moves distally, the cage closes.
(28) FIG. 27. Section view—The tip of the device. In this embodiment the extractor tube also acts at the distal arm. The extractor tube rotates at high speed while cage connector does not rotate. The bearing facilitates this relative movement.
(29) FIG. 28. Schematic of a device of the invention with a control mechanism located within the cage.
(30) FIG. 29. Schematic of a device of the invention with a control mechanism located distally of the cage.
(31) FIG. 30. Schematic of the device having a sheath covering the elongated control member and adjustable to cover the cage.
(32) FIG. 31. Schematic of the device of the invention showing how thrombolytic agents may be infused through the extractor.
(33) FIG. 32. Schematic of the device of the invention showing how thrombolytic agents may be infused between the extractor and the sheath
(34) FIG. 33. Schematic of the device of the invention showing how thrombolytic agents may be infused through holes or perforations formed in the sheath.
(35) FIG. 34. Schematic of a radially expansible member formed from a single strut.
(36) FIGS. 35A and 35B. Schematic of a radially expansible member formed from two struts.
(37) FIG. 36. An example of the radially expansible member made from a series of wires, and fused or twisted for connection (shown as a flat pattern).
(38) FIG. 37. An example of a braided expansible member with the wires twisted at the intersections to limit the movement of the wires with respect to each other (shown as a flat pattern).
(39) FIG. 38. An example of a braid configuration for the creation of a braided radially expansible member, with twisted wires (for struts) and fused ends (shown as a flat pattern).
(40) FIG. 39. An example of a braid configuration for the creation of a braided radially expansible member, with twisted wires to create struts.
DETAILED DESCRIPTION OF THE INVENTION
Cage and Filter
(41) The cage can be made in many different ways, such as from a braid, a series of wires, laser cut tubes or a combination of them. The cage also may act as a filter or be a structure for the filter at the distal part. The cage can be made of different materials such as, but not limited to, polymeric, metal such as stainless steel Nitinol or cobalt chromium, or ceramic; or a combination of these materials. The proximal side of the cage is generally open and allows thrombus into the cage. The distal part of the cage is suitably constrained onto a tube or wire with small diameter and the proximal part of the cage is connected to a tube with larger diameter. A sheath may cover the entire device at delivery and at retrieval.
(42) A connector, which can be a wire or tube and connects the distal end of the cage to user or controls the distal movement of the cage, is called the distal arm. Another connector, which can be a wire or tube and connects the proximal end of the cage to user, is called the proximal arm.
(43) Once the cage is assembled and opened, section 202 provides a passageway for thrombus into the cage, while section 201 prevents large thrombus passing the cage (1).
(44) In FIGS. 2 and 3, an example of a cage which has been laser cut from Nitinol tube is shown. The laser cuts have the same feature as the braided mesh. It provides a passageway on the proximal side and acts as filter on the distal side. It may also carry circumferential elements for cutting through thrombus and separating thrombus from the wall.
(45) By pushing the proximal and distal ends of the cage axially towards each other the diameter of the cage and its radial force may increase. By pulling the sides away from each other the diameter and the radial force of the cage may decrease.
(46) Relative movement of the distal and proximal arms controls the distance between the distal and proximal sides of the cage; this adjusts the diameter and radial strength of the cage. If the distal arm is fixed and the proximal arm is pulled proximally by the user, the diameter of the cage becomes smaller. If the proximal arm is fixed and the distal arm is being pulled, the diameter of the cage increases.
(47) The cage may also have a circumferential cutting element for removing/scraping thrombus from the vessel wall. This may be contained around or within the cage and may be composed of a round wire, flat wire, blade or a combination of these. FIG. 4 shows the cage with a flat wire attached the outside of the cage; the wire can scrape thrombus from the vessel wall. FIG. 5 shows the cutting element internal to the cage, while FIG. 6 shows the cutting element of the cage as one part (in this case from a laser cut tube). The cutting/scraping element may also be tapered at an angle (FIG. 7).
A Cage with Self Adjustable Diameter Control Mechanism
(48) In the case of treating a tapered vessel, the cage diameter should be adjustable while it is pulled along the lumen. Also in the case of obstruction such as vascular valve it is desirable that the device be able to manoeuvre through it. Therefore a mechanism which can control the diameter of the cage by changing the resistance force is desirable. Presented here is a mechanism to control the diameter of the cage based on resistance forces.
(49) As the cage moves through a reducing tapered vessel (pulling the proximal arm), the vessel exerts a force on the cage. When the force from the vessel exceeds the total force including the preset force from the resistance mechanism (set by the user), the distal arm moves distally relative to the proximal arm; this closes the cage. The next section includes some embodiments of the self-adjustment mechanisms.
(50) The control mechanism may contain friction elements, springs, pneumatics, hydraulics, simple weight, or a combination of these elements.
Resistance Mechanism: Sliding
(51) In this embodiment of the invention (FIGS. 8A, 8B, and 9), the cage (3) is made from a laser cut self-expanding tube. The cage opens when 1b and 2b move closer together, and closes when 1b and 2b move apart. The mechanism for controlling the diameter and force exerted by the cage on the vessel wall is the basis for the current invention.
(52) The device, as shown in FIGS. 8A and 8B, consists of a cage (3) which has a distal end (1b) and a proximal end (2b), a distal arm (1), a proximal arm (2), and a handle. The control mechanism is comprised in the handle, and comprises a first part in the form of a housing (2a) having a guidance path, a second part in the form of a sliding block (1a) configured for sliding movement along the guidance path of the housing (2a). Force controlled resistance means is provided in the form of a brake adapted to resist movement of one or the arms relative to the other. In this embodiment, the brake comprises a friction screw (4) mounted on the housing (2a) and adjustable to apply a compression force against the sliding block (1a) to provide resistance to movement of one arm relative to the other, and in the case of the device being passed along a vessel that tapers inwardly, resistance to the compression of the cage which has the effect of keeping the periphery of the cage in contact with the vessel wall.
(53) The process begins in an expanded state in the vessel as shown in FIG. 8A. The opening and closing of the cage is governed by the relative movement of the sliding block (1a) to the handle (2a). As the cage is pulled by the handle through an obstruction or the tapered section of the vessel (5), force from the vessel wall is exerted to the cage. This force is transferred to the sliding block (1a). If the force applied to the block 1a is larger than the preset friction force, then the block 1a slides forward from its position in FIG. 8A to its position in FIG. 8B. This allows the cage to conform to the shape of the narrower vessel. The force exerted by the cage on the vessel is therefore dictated in part by the ease of movement of the sliding block relative to the handle; this is controlled by the friction screw.
Resistance Mechanism: Sliding and Spring
(54) FIGS. 11A and 11B show an alternative embodiment of the resistance mechanism in which parts described with reference to FIG. 10 are assigned the same reference numerals. In this embodiment, a compression spring (6) is disposed along the guide path between the housing (2a) and the sliding block (1a). The housing (2a) is connected to the proximal arm (2) and the block (1a) is connected to the distal arm (1). Thus, compression of the cage (3) into a contracted orientation causes the distal arm (1) to extend, causing compression of the spring. In this manner, the cage is biased into an expanded orientation when it is being passed along a vessel that is narrowing, thereby maintaining contact between the cage and the vessel wall. A friction screw (4) is mounted on the housing (2a) and is adjustable to apply a compression force against the block (1a) and thereby provides further resistance to movement of one arm relative to the other, and in the case of the device being passed along a vessel that tapers inwardly, again provides resistance to the compression of the cage which has the effect of keeping the periphery of the cage in contact with the vessel wall.
(55) FIGS. 11A and 11B show an alternative embodiment of the resistance mechanism in which parts described with reference to FIGS. 8 to 10 are assigned the same reference numerals. In this embodiment, the self adjusting mechanism comprises a movable stop (7) that is movable to adjust the length of the guidance path and, thus, the degree of compression of the spring. Thus, the force that the spring applies can be varied by changing the position of the movable stop (7) along the guidance path.
Resistance Mechanism: Spring with Adjustable Spring Constant
(56) In this embodiment the distal arm (1) is attached to a flat spring (22). The other side of the spring (22) is fixed respect to proximal arm (2) through a solid handle (20). Since the spring constant of a flat spring changes with its length, a mechanism for adjusting its length (21) can slide over the spring to control its deformation. When the sliding part (21) is down (FIG. 12) the spring constant is the lowest which means it allows higher displacement of inner tube (1) at a lower force. When the sliding tube (21) rises (FIG. 13), the spring constant (22) increases which allows less displacement of inner tube (1). This effectively reduces the cage diameter (3). FIG. 14 shows a 3D representation of the mechanism.
The Extraction Mechanism
(57) The extraction system may consist of suction, or a rotating tube/wire with a means of transformation and/or maceration on the outer surface; the extraction system may also contain a combination of these mechanisms. The rotating extractor may be manufactured from one part or made from several attachments. For example, the extraction mechanism may comprise a wire (42) wrapped around an extraction core tube (43) (FIG. 15). This tube may be placed over the distal arm (1) of the cage and inside the proximal arm (2). Alternatively, the distal arm may be used as the extraction core tube. The distal side of the extraction core tube may be close to the distal end of the proximal arm (2). As the extraction tube turns at high speed thrombus is forced proximally between the extraction tube and the proximal arm. The distal end of the extraction mechanism may be located inside the cage (FIG. 1).
(58) The wire may have varying cross sections along the device for different means; from circular, rectangular or triangular cross sections. The wire can be from different materials such as stainless steel, Nitinol, or polymers. Once the wire is wrapped around the tube, it might be completely fit around the tube (41) or be partially fit at a distance (43) from the rotating tube (41) surface (FIG. 16).
(59) The proximal arm may also contain a side window (FIG. 17) to improve access of the extractor to thrombus. The extractor may also be formed from one machined part rather than a wire wrapped around a tube. The rotating extractor will likely contain sharp cutting edges at its distal end to break up matter prior to extracting it. The non-rotating proximal arm may also have a leading edge/cutting element (FIGS. 18A and 18B) which helps to break down thrombus, while also increasing the size of the path at the entrance of the extractor. The proximal arm may have more than one leading edge/cutting element to break down matter; FIGS. 19A, and 19B show the proximal arm with two leading edges. The leading edge/cutting element may form part of the proximal arm (as shown) or alternatively be a separate part attached to the non-rotating proximal arm. The extractor may also contain an additional port at the proximal end where suction can be added to enhance thrombus extraction, and to attract thrombus towards the extractor. FIG. 20 shows an embodiment in which the rotating tip and helical wire are attached to the distal arm for rotation therewith. FIG. 21 shows the extractor with the cage. The extractor may also be eccentric to the centre of the cage; FIG. 22 shows the extractor eccentric to the centre cage and adjacent to it while FIG. 23 shows the tip of the cage away from the centre of the cage. In both FIGS. 22 and 23 the extractor may be stationary or rotate around the centreline.
(60) The extractor may have a varied pitch along its length. One embodiment of this is shown in FIG. 24, where a section of the extractor has a reduced pitch, and the non-rotating tube has a number of small holes (acting as a filter) in it. This may allow any debris to be squeezed, forcing residual fluid through the holes and into the vessel while the remaining debris continues to be extracted.
(61) The extraction mechanism in combination with the cage may have various functions along the device. In one embodiment, the extractor breaks down the thrombi into relatively big pieces which are small enough to enter the inlet of tube and big enough not to pass through the filter. Once the thrombus is inside the tube, the extractor, breaks them down into smaller pieces, make it easier to transfer along the catheter. Then, the extraction system may have a means of extraction such as helical wire or vacuum. The matter removed will be collected in a suitable collection means, for example a blood bag, or syringe or similar.
(62) The helical formation may have a cutting edge, and which is adapted to rotate with the helical formation and cut or break up thrombus for extraction. The cutting edge may be a blade ore the like, and may be disposed at or close to an end of the helical formation. The extractor tube may also have a cutting edge, and may be adapted to rotate.
Combination of the Cage and Extractor
(63) The device contains both a cage with a self adjustment mechanism, and an extractor. FIG. 25 shows an embodiment of the distal end of the device. The device is opened and closed by the relative movement of the proximal and distal arms, while the extractor rotates over the distal arm and within the proximal arm. The proximal arm may also contain a window for extraction. A sheath covers the entire device during delivery and retrieval.
(64) FIG. 26 shows another embodiment of the distal end of the device, with the cage and extractor combined. In this embodiment, the rotating extractor also acts at the distal arm; the relative movement of which opens and closes the cage. A ball bearing has been included to facilitate contact of the rotating extractor/distal arm and non-rotating proximal arm and cage (FIG. 27).
Device with Control Mechanism within Cage
(65) FIG. 28 shows an embodiment of the device in which the control mechanism is disposed within the cage. In this embodiment, a control mechanism is provided within the cage (3) and comprises a first part operably connected to the proximal arm (2), a second part operably connected to the distal arm (1), and a helical spring (6) connecting the first and second parts. In use, as the cage passes along a vessel that is tapering inwardly, the control mechanism ensures that a force controlled resistance is applied to the cage as it contracts, thereby ensuring that the cage remains in contact with the walls of the vessel.
Device with Control Mechanism Mounted Distally of Cage
(66) FIG. 29 shows an embodiment of the device in which the control mechanism is disposed distally of the cage. In this embodiment, the device comprises a proximal arm (2), which is connected to a proximal part (2b) of the cage and which extends through, and distally beyond, the cage, and a distal arm (1) which extends distally of the cage (3). The control mechanism comprises a first part (block 1b) operably connected to an end of the proximal arm, a second part operably connected to the distal arm (1), and a helical spring (6). In use, as the cage passes along a vessel that is tapering inwardly, the control mechanism ensures that a force controlled resistance is applied to the cage as it contracts, thereby ensuring that the cage remains in contact with the walls of the vessel.
Device with Outer Sheath
(67) Specifically, FIG. 30 shows an embodiment of the device of the invention in which a sheath (8) is provided that covers the elongated control member. In this embodiment, the device can be manipulated such that the cage (3) is contracted and withdrawn within the sheath, which will thus keep it in a contracted orientation
Delivery of Liquid Agent to Vessel Lumen
(68) The device of the invention may also be employed to deliver liquid agent, for example a thrombolytic agent which can break down thrombus, to the vessel lumen. This may be achieved in a number of different ways including: The direction of rotation of the extractor screw can be changed to infuse rather than extract. Inject through the hollow distal arm. Inject through a lumen between the distal arm and the extractor tube (proximal arm) (FIG. 31) Injected in between the extractor tube (proximal arm) and the sheath (FIG. 32). Injected through cavities in the sheath (FIG. 33). The location of the sheath and cavities can be adjusted along the catheter length. One of, or a combination of, the above methods of infusion.
(69) Generally, the liquid agent would be injected into the delivery lumen, which may be any of the above. Alternatively, the liquid agent may be delivered slowly by means of a drip feed. As indicated above, the liquid agent may be delivered in a number of different ways, for example through a hollow distal arm (which has the advantage of being capable of delivering liquid agent distally of the cage), through a lumen formed between the distal arm and the proximal arm (also referred to as the extractor tube), or through a lumen formed between the proximal arm and the outer sheath.
Design of Radially Expansible Member
(70) FIGS. 34 to 39 describe embodiments of the radially expansible member forming part of the device of the invention, and specifically braid configurations that may be employed in radially expansible members.
(71) The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail without departing from the spirit of the invention.
