Mechanical thrombus removal device

Abstract

A medical device includes a flexible cannula including an inner tube having a proximal end and a distal end and a series of slits cut along a length thereof between the proximal end and the distal end; and an outer sheath softer than the inner tube. Discrete portions of the outer tube are connected to the inner tube along a longitudinal axis of the sleeve. The area where there is no connection between the outer sheath and the inner tube allows some relative movement between the outer sheath and the inner tube, resulting in increased flexibility of the cannula.

Description

Technical Field

[0001] The present invention relates generally to apparatus and methods for use in cardiac surgery, and in particular for thrombus removal. Background Art

[0002] Removal of obstructions, such as blood clots, from the vasculature is an important and life-saving technique.

[0003] Physicians usually insert a cannula inserted into the vascular system to remove such obstructions. A vacuum syringe is usually used to generate negative pressure (vacuum) at the proximal side of the cannula, causing the obstruction to be sucked into the syringe through the cannula. In many cases, the clot is too large and too formed to fit through the cannula, resulting in the thrombus remaining at the distal end of the cannula, rather than traveling back into the syringe through the cannula, because it is only held in place by the force generated by the negative pressure in the cannula. The physician must then carefully remove the cannula from the body so as not to break the vacuum and loosen the clot. Therefore, relying solely on the force generated by the vacuum can cause the clot to be released back into the blood vessel during extraction.

[0004] There is therefore a need for an improved device for removing thrombus. Summary of the invention

[0005] The present invention seeks to provide an improved apparatus for removing thrombus, as described in more detail below.

[0006] Thus, in accordance with one non-limiting embodiment of the present invention there is provided a medical device comprising: a flexible sleeve comprising an inner tube having a proximal end and a distal end and a series of slits cut along its length between the proximal and distal ends; and an outer sheath softer than the inner tube, wherein discrete portions of the outer tube are connected to the inner tube along the longitudinal axis of the sleeve, and areas where there is no connection between the outer sheath and the inner tube allow some relative movement between the outer sheath and the inner tube, thereby resulting in increased flexibility of the sleeve.

[0007] According to one non-limiting embodiment of the present invention, the outer sheath is made of a meltable polymer and the discrete portions of the outer sheath include melted portions adhered to the exterior of the inner tube.

[0008] According to a non-limiting embodiment of the present invention, the slit enables the inner tube to bend in any direction through expansion and compression of the slit.

[0009] According to a non-limiting embodiment of the present invention, the medical device also includes: a thrombus removal device, which includes a distal removal element, which is connected to the inner shaft at a distal portion of the distal removal element, and the distal removal element is located within an outer shaft, and the outer shaft is configured to guide the distal removal element toward a target site, wherein the distal removal element includes radial elements, and the radial elements are exposed by retracting the outer shaft, and wherein the distal removal element is opened by pulling the inner shaft relative to the intermediate shaft, thereby compressing the distal removal element and forcing the radial elements to open radially outward to an open position.

[0010] According to one non-limiting embodiment of the invention, a membrane covers the radial elements, and pulling the inner shaft causes the distal end of the membrane connected to the radial plunger to fold back onto the membrane itself and create a vacuum. The membrane may be a blood-impermeable membrane.

[0011] According to a non-limiting embodiment of the present invention, the inner shaft, the intermediate shaft and the outer shaft are concentric with each other.

[0012] According to one non-limiting embodiment of the invention, some of the radial arms have a larger radial diameter in the open position than other of the radial arms.

[0013] According to one non-limiting embodiment of the present invention, some of the radial arms have a sinusoidal or other wavy shape that is different from other of the radial arms.

[0014] According to one non-limiting embodiment of the present invention, an adjustable sealing valve is coupled to the flexible sleeve, the adjustable sealing valve comprising a fixed first end and a second end that is free to rotate relative to the first end, and wherein a deformable inner sleeve is coupled to the first end and the second end, and wherein radially placed recesses on the first end are configured to receive protrusions placed on the second end so as to lock the second end into the first end and prevent rotation of the second end, and wherein rotation of the second end causes the deformable inner sleeve to deform and collapse inwardly in a radial direction so as to form a seal around an object of any diameter passing through the deformable inner sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be more fully understood and appreciated from the following detailed description in conjunction with the accompanying drawings, in which:

[0016] Figure 1 is a simplified diagram of a thrombus removal device according to one non-limiting embodiment of the present invention.

[0017] Figure 2is a simplified illustration of the distal removal elements revealed by retracting the outer shaft of the device.

[0018] Figure 3 is a simplified pictorial representation of the thrombus removal device in position with the distal removal element fully exposed.

[0019] Figure 4 is a simplified illustration of a mechanical removal element in an open configuration.

[0020] Figure 5 is a simplified diagram of a method for removing a thrombus from a body cavity in accordance with one non-limiting embodiment of the present invention.

[0021] Figure 6 is a simplified illustration of a mechanical removal element in its open position.

[0022] Figure 7 is a simplified illustration of another thrombus removal device according to one non-limiting embodiment of the present invention.

[0023] Figure 8 Yes Figure 7 Simplified illustration of a device being released from its curled state.

[0024] Fig. 9 It is completely loose and has no external shaft. Figure 7 Simplified diagram of the device.

[0025] Fig.10 yes Figure 7 A simplified diagram of the shafts of a device in which an outer shaft can move to surround the device and radially compress the radially compressible elements and membrane.

[0026] Fig.11 Before the inner tube is pulled back and a local vacuum is induced Figure 7 Simplified diagram of the device.

[0027] Fig.12 is one in which once the inner shaft is pulled back, the membrane turns inwards Figure 7 Simplified diagram of the device.

[0028] Fig.13 In a blocked body cavity Figure 7 Simplified diagram of the device.

[0029] Fig.14 yes Figure 7 Simplified illustration of the device swallowing an obstruction due to the vacuum created by pulling back the inner shaft.

[0030] Fig.15 is a simplified diagram of a thrombus removal device according to another non-limiting embodiment of the present invention.

[0031] Fig.16is a simplified illustration of a cannula having a chamfered distal end showing a toothed ring with inwardly directed barbs.

[0032] Fig.17 is a simplified illustration of the insertion of a chamfered cannula into an occluded blood vessel.

[0033] Fig.18 is a simplified illustration of a cannula being advanced to the site of a thrombus.

[0034] Fig.19 is a simplified diagram of an aspirated thrombus.

[0035] Fig.19A is a cross-sectional view showing how a blood clot becomes lodged in the barbs of the toothed ring.

[0036] Fig. 20 is a simplified diagram of a thrombus removal device according to another non-limiting embodiment of the present invention.

[0037] Fig.21 and Fig. 22 is a simplified diagram of an adjustable sealing valve that may be attached to the proximal end of a cannula.

[0038] Fig.23 is a simplified diagram of an adjustable valve where the inner tube is deformed to an intermediate level to seal against a treatment tool.

[0039] Fig.24 is a simplified diagram of a flexible cannula constructed by combining an inner tube having proximal and distal ends and a series of slits cut along the length.

[0040] Fig.25 is a simplified diagram of the gap in the connection area between the inner tube and the outer jacket.

[0041] Fig.26 is a simplified diagram of the slits that reduce wall friction in the inner tube.

[0042] Fig. 27 is a simplified illustration of a dual introducer sheath in accordance with one non-limiting embodiment of the present invention.

[0043] Fig.28 is a simplified illustration of a dual sheath device showing the orientation of the shaft and hub prior to insertion into a blood vessel.

[0044] Fig.29 is a simplified illustration of the outer sheath as it is pulled back relative to the inner sheath causing the hubs to connect.

[0045] Fig.30 is a simplified illustration of the hub in its locked position.

[0046] Fig.31 is a simplified diagram of the inner sheath being removed from the outer sheath. DETAILED DESCRIPTION

[0047] Figure 1 A thrombus removal device 10 is shown, which includes a mechanical removal element ( Figure 1 ), the mechanical removal element is attached to the inner guidewire shaft 12 (through its distal end) and is located within the outer shaft 11, which enables it to be guided toward the target site. The device 10 can be inserted into a body cavity 101 using standard percutaneous techniques.

[0048] Figure 2 The distal removal element 13 is shown exposed by retracting the outer shaft 11. This can be done once the distal end of the device 10 has reached the thrombus 101. Figure 3 The thrombus removal device 10 is shown in position with the distal removal element 13 fully exposed.

[0049] Figure 4 The mechanical removal element 13 is shown in an open configuration. In one embodiment of the present invention, a spiral design is shown, wherein the mechanical removal element 13 includes elongated flexible radial arms 16 (such as wire or braid, which may be made of nitinol, stainless steel or other suitable material) formed as a spiral or arcuate wrap of the wire. The element 13 is opened by pulling the inner shaft 12, the distal end of the element 13 being connected to the inner shaft 12 against the intermediate shaft 14, thereby compressing it and forcing the radial arms 16 to open radially outward. This is done using a control handle (not shown). The physician can set a number of opening diameters depending on the patient's anatomical structure.

[0050] Figure 5 is a schematic representation of a method for removing a thrombus from a body cavity. After radially opening the distal removal element arms 16, the physician uses the control handle to rotate the inner shaft 12, thereby rotating the distal removal element 13. This action twists the thrombus 101, thereby breaking its adhesion to the arterial wall and twisting the thrombus around the device 10. The thrombus can then be pulled back and removed.

[0051] Figure 6 The mechanical removal element 13 is shown in its open position. The inner shaft 12 is in its retracted position, with the element 13 pressed against the inner shaft 12 and the intermediate shaft 14. Thus, the distal removal element radial arms 16 are radially open. The outer shaft 11 is shown in a retracted state. In other embodiments, the device 10 may have less than three arms 16, such as one arm, or more than three arms. It should be noted that some radial arms 16 may have a larger radial diameter in the open position than other radial arms 16. It should also be noted that some radial arms 16 may have a different sinusoidal or other wavy shape than other radial arms 16.

[0052] Figure 7Another thrombus removal device 20 that can be inserted into a body cavity using standard percutaneous techniques is shown. The device is shown in its fully curled state. An outer shaft 26 is used to maintain the various elements of the device 20 in their curled state to allow percutaneous delivery. The distal end 21 ensures that the distal end of the device is atraumatic.

[0053] Figure 8 The steps of deploying the device 20 from its crimped state are shown. Element 24 is a self-expanding radial structure (made of a self-expanding material, such as but not limited to a superelastic alloy, such as Nitinol) that can be moved from a crimped state to a non-crimped state. A blood-impermeable membrane 23 covers the self-expanding radial element 24. The membrane 23 extends from the proximal end of the device to its distal end. The self-expanding plunger element 22 is also covered by the membrane.

[0054] Fig. 9 The device 20 is shown fully expanded and without an outer shaft 26. In this figure, for clarity, the end 21 connected to the inner shaft (not shown) extends distally. The membrane 23 surrounds the radial expansion element 24 and the radial plunger element 22. The radial expansion element 24 is connected to the intermediate shaft (not shown). All shafts (inner shaft, intermediate shaft and outer shaft) are concentric. This is designed so that the inner shaft can move relative to the stationary intermediate shaft.

[0055] Fig.10 The arrangement of the shafts of an embodiment is shown, wherein the outer shaft 26 is movable to surround the device 20 and radially compress the radially compressible element 24 and the membrane 23. The radially compressible element 24 is fixed to the intermediate shaft 27 and extends distally. The membrane 23 is connected at its distal end to the radial plunger 22, which is in turn connected to the inner shaft 28. Once the outer shaft 26 is pulled back, the radially compressible element 24 opens outward. When the inner shaft 28 is pulled back, the distal end of the membrane 23 connected to the radial plunger 22 folds back on itself and creates a vacuum.

[0056] Fig.11 The device 20 is shown before the inner tube 28 (not shown) is pulled back and a partial vacuum is induced.

[0057] Fig.12 The device 20 is shown with the membrane 23 inverted inwardly once the inner shaft 28 has been pulled back. The radial piston 22 is shown in its rearward state and the folding of the membrane 23 is visible.

[0058] Fig.13 The device 20 is shown in an obstructed body lumen. The device is advanced toward the obstruction 202 and then the outer shaft 26 (not shown) is retracted, thereby expanding the radially compressible element 24 and the membrane 23.

[0059] Fig.14 The obstruction 202 is shown being "swallowed" (ie, pulled in) by the device 20 due to the vacuum created by pulling back the inner shaft 28.

[0060] Reference now Fig.15 , which shows a thrombus removal device according to another non-limiting embodiment of the present invention. Fig.15 A cannula 300 is shown having a ring or rings 302 at its distal end 301. Each ring 302 includes a series of inwardly extending barbs 303 designed to hook a thrombus and prevent its release back into the circulation system in the event of a loss of vacuum during cannula withdrawal. The barbs 303 may have a rearward or forward orientation relative to the longitudinal axis of the cannula 300. The cannula 300 may have a blunt end, or may be cut at a chamfer to facilitate clot engagement. Fig.15 A blunt cannula is shown, demonstrating a toothed ring with a plurality of inwardly directed barbs directed toward the distal end of the catheter.

[0061] Fig.16 A cannula 300 is shown having a chamfered distal end 304, demonstrating a toothed ring 302 with a plurality of inwardly directed barbs 303, which are directed toward the distal end of the catheter.

[0062] Fig.17 The chamfered cannula 300 is shown inserted into an occluded blood vessel 305 where a thrombus 306 is located.

[0063] Fig.18 Cannula 300 is shown advanced to the site of a thrombus.

[0064] Fig.19 Aspirated thrombus 306 is shown and retained on distal end 304 of cannula 300 . Fig.19A is a cross-sectional view showing how a thrombus 306 is caught on the barb 303 of the toothed ring 302 .

[0065] PCT patent application PCT / US2021 / 042676 (published as WO 2022 / 020539) describes another obstruction capture device. The structure of the obstruction capture device includes a tapered cone having a grasper arm disposed at its distal end. The grasper arms close radially inward against the obstruction so that the obstruction is pulled into the conical mesh. The risk associated with this type of device is the insertion of a relatively large captured clot into an aspiration cannula having a diameter smaller than the obstruction. Once the captured clot is pulled into a cannula having a diameter smaller than the size of the clot, portions of the clot may be torn off and returned, thereby blocking the blood vessel.

[0066] The present invention provides a solution to this problem, as now described.

[0067] Reference now Fig. 20 , which shows a thrombus removal device according to another non-limiting embodiment of the present invention. Fig. 20 A self-expanding conical mesh 310 is shown positioned proximate to a capture (grasper) element 311. A mesh cone 312 (which may be configured similar to a stent mesh) is added over the capture element 311 (or proximate to these elements) such that once capture is achieved, the capture element 311 with the captured clot is pulled into the mesh cone 312. This accomplishes two primary purposes: It enhances capture efficiency by allowing the outer tube to advance over a section of the mesh cone 312, compressing the cone 312 radially inward and further capturing the proximal end of the clot. Secondly, it enhances insertion of the captured clot into the cannula by deforming the shape of the clot and preventing the clot from being sheared by the cannula wall because the clot is captured within the mesh cone 312.

[0068] During a typical surgery, a physician may attempt to pass a therapeutic device through a cannula having a proximal end outside the body and a distal end at a determined target site. The devices passed through the cannula may have different diameters, ranging in size such as guidewires and dilators. During the interchange, excessive blood loss may occur. Typically, a gasket within the proximal end of the cannula is used to limit blood loss; however, these gaskets have a limited range of sizes and cannot provide adequate sealing when the size range is large. In addition, in the case of a suction cannula, the gasket serves not only as a blood loss prevention element, but also as a seal to prevent the loss of vacuum strength when negative pressure is applied. There is a need for a seal that allows for a wide diameter variation and also acts as an effective vacuum seal.

[0069] Now refer to the attached Fig.21 and Fig. 22 , which shows an adjustable sealing valve 320 that can be attached to the proximal end of a cannula (not shown). The seal 320 has a deformable inner sleeve or tube 321 (e.g., Fig. 22 323) wherein the first end 322 is fixed and the second end 323 is free to rotate relative to the first end 322. A series of radially placed notches 324 on the first end 322 receive protrusions 325 placed on the second rotating end 323 to prevent rotation of the second end 323 by locking the second end 323 into the first end 322. As the second rotatable end 323 rotates, the deformable inner sleeve 321 deforms and collapses inwardly in a radial direction so that it effectively forms a seal around any diameter of a therapeutic device passing therethrough. The seal diameter may range from 0.5 mm to 30 mm.

[0070] Fig.23 An adjustable valve 320 is shown with the inner tube 321 deformed to an intermediate level to seal against a treatment tool 326. The adjustable sealing valve 320 seals equally well under high and low pressure conditions (vacuum and positive pressure) and can seal against small diameter objects (such as guidewires) and large diameter objects (such as dilators).

[0071] The flexibility of an inhalation cannula is often an important issue for physicians. There are many tradeoffs when it comes to flexibility that may hinder the correct function of the cannula. In order to increase flexibility, manufacturers may sacrifice important aspects of the cannula, such as compressibility, trackability, and strength.

[0072] Reference now Fig.24 , which shows a flexible sleeve 330 constructed by combining an inner tube 331, also called a subcutaneous tube 331 (which can be made of steel or steel alloy or any other suitable rigid material), the inner tube 331 has a proximal end 332 and a distal end 333 and a series of slits 334 cut along the length of the inner tube 331. The slits 334 enable the tube 331 to be bent in any direction by the expansion and compression of the slits 334. An outer softer sheath 335 is partially connected to the inner tube 331. The outer softer sheath 335 can be made of a meltable polymer, such as but not limited to nylon, polyether block amide (PEBA) and other materials. Examples of PEBA include the trade names PEBAX (from Arkema) and VESTAMID (from Evonik Industries). Discrete portions of the outer sheath 335 can be bonded to the inner tube 331 at discrete positions along the longitudinal axis of the sleeve 330 (such as by melting the polymer so that the polymer adheres to the outside of the inner tube 331). The areas where no connection exists between the outer sheath 335 and the inner tube 331 allow some relative movement between the sheath 335 and the subcutaneous tube 331 , resulting in increased flexibility of the cannula 330 .

[0073] Fig.24 A sleeve 330 is shown having a slit 334 along its longitudinal length and having an outer sheath 335 which may be made from a variety of polymers.

[0074] Fig.25 A gap 336 in the connection area between the inner tube 331 and the outer jacket 335 is shown.

[0075] Fig.26 The cut slits 334 shown along the subcutaneous tube may also be used to reduce the wall friction between the fluid (eg, blood and clot material) flowing through the inner tube 331 and the inner wall of the tube 331 by reducing the Reynolds number.

[0076] Reference now Fig. 27, which shows a dual introducer sheath 350 that can be used during percutaneous surgery according to an embodiment of the present invention. Sheath 350 includes two concentric sheaths - an inner sheath 370 and an outer sheath 360. Both sheaths are composed of a shaft and a hemostatic hub, so that the inner sheath 370 has a shaft 354 and a hub 353. Similarly, the outer sheath 360 has a shaft 351 and a hub 352. A dilator (not shown) can be used to facilitate vascular access, as is known in the art. The shaft hub is designed to provide a hemostatic seal. The distal end of the outer shaft 351 has a chamfer 355 to prevent damage to the blood vessel during insertion.

[0077] Fig.28 A dual sheath device 350 is shown illustrating the orientation of the shaft and hub prior to insertion into a blood vessel. The inner hub 353 may have a connecting segment 356 that may be used to connect the inner hub 353 to the outer hub 352.

[0078] Fig.29 The outer sheath 360 is shown pulled back relative to the inner sheath 370 so that the hubs 352 and 353 are connected. When the outer sheath 360 is in its retracted position, the conical mesh 357 connected to the inner shaft 354 is exposed.

[0079] Fig.30 Hubs 352 and 353 are shown in their locked positions.

[0080] Fig.31 The inner sheath 370 is shown removed from the outer sheath 360.

[0081] The double sheath system can be used to remove large obstructions from the vascular system. Any therapeutic device used to capture and remove obstructions from the vascular system can pass through the double sheath system 350. If the obstruction is larger than the diameter of the sheath system, the therapeutic device can be pulled back to the position where the obstruction is located within the conical net 357. At this time, the inner sheath 370 can be removed from the outer sheath 360, thereby safely removing the obstruction from the body. Utilizing this double sheath system, the obstruction can be removed while the protective sheath is kept in place (the outer sheath is kept in the vascular system). This is different from the prior art, in which a single sheath is used, and therefore a vascular surgery is required when removing large obstructions.

[0082] Note that any embodiment described herein may be combined with one or more other embodiments described herein.

Claims

1. A medical device comprising: a flexible sleeve comprising an inner tube having a proximal end and a distal end and a series of slits cut along the length of the inner tube between the proximal end and the distal end; as well as An outer sheath that is softer than the inner tube, wherein discrete portions of the outer tube are connected to the inner tube along the longitudinal axis of the sleeve, and areas where there is no connection between the outer sheath and the inner tube allow some relative movement between the outer sheath and the inner tube, thereby resulting in increased flexibility of the sleeve.

2. The medical device according to claim 1, wherein: The outer jacket is made of a meltable polymer and the discrete portions of the outer jacket include melted portions adhered to the exterior of the inner tube.

3. The medical device according to claim 1, wherein: The slits enable the inner tube to be bent in any direction through expansion and compression of the slits.

4. The medical device according to claim 1, wherein: The medical device also includes: A thrombus removal device comprising a distal removal element coupled to an inner shaft at a distal portion of the distal removal element and located within an outer shaft configured to guide the distal removal element toward a target site, wherein the distal removal element comprises radial elements exposed by retracting the outer shaft, and wherein the distal removal element is opened by pulling the inner shaft relative to the intermediate shaft, thereby compressing the distal removal element and forcing the radial elements to open radially outward to an open position.

5. The medical device according to claim 4, wherein: A membrane covers the radial elements, and pulling on the inner shaft causes the distal end of the membrane connected to the radial plungers to fold back onto the membrane itself and create a vacuum.

6. The medical device according to claim 5, wherein: The membrane is a blood-impermeable membrane.

7. The medical device according to claim 5, wherein: The inner shaft, the intermediate shaft, and the outer shaft are concentric with each other.

8. The medical device according to claim 4, wherein: Some of the radial arms have a larger radial diameter in the open position than other of the radial arms.

9. The medical device according to claim 4, wherein: Some of the radial arms have a different sinusoidal or other wavy shape than other of the radial arms.

10. The medical device according to claim 1, wherein: An adjustable sealing valve is coupled to the flexible sleeve, the adjustable sealing valve comprising a fixed first end and a second end that is free to rotate relative to the first end, and wherein a deformable inner sleeve is coupled to the first end and the second end, and wherein radially placed recesses on the first end are configured to receive protrusions placed on the second end so as to lock the second end into the first end and prevent rotation of the second end, and wherein rotation of the second end causes the deformable inner sleeve to deform and collapse inwardly in a radial direction so as to form a seal around an object of any diameter passing through the deformable inner sleeve.

11. A medical device comprising: A thrombus removal device comprising a distal removal element coupled to an inner shaft at a distal portion of the distal removal element and located within an outer shaft configured to guide the distal removal element toward a target site, wherein the distal removal element comprises radial elements exposed by retracting the outer shaft, and wherein the distal removal element is opened by pulling the inner shaft relative to the intermediate shaft, thereby compressing the distal removal element and forcing the radial elements to open radially outward to an open position.

12. The medical device according to claim 11, wherein: A membrane covers the radial elements, and pulling on the inner shaft causes the distal end of the membrane connected to the radial plungers to fold back onto the membrane itself and create a vacuum.

13. The medical device according to claim 11, wherein: The inner shaft, the intermediate shaft, and the outer shaft are concentric with each other.

14. The medical device according to claim 11, wherein: Some of the radial arms have a larger radial diameter in the open position than other of the radial arms.

15. The medical device according to claim 11, wherein: Some of the radial arms have a different sinusoidal or other wavy shape than other of the radial arms.

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