Patent Application
20190209190
This invention relates generally to devices deployed from endovascular catheters for removing thrombi, and methods for using the same.
Thrombi, also known as “blood clots,” can form in both arterial and venous vessels. Thrombi, when formed in or embolized into such vessels can cause adverse events by blocking the blood flow downstream in the blocked vessel.
Thrombi may be treated/removed by thrombolytic therapy and/or mechanical thrombectomy. Thrombolysis dissolves a thrombus using pharmacological agents such as tissue plasminogen activator drug (tPA). Catheter-delivered thrombectomy devices generally fall into two categories and combinations thereof. Aspiration catheters function by suctioning the thrombus out of the blood vessel. Mechanical devices are designed to contact and dislodge the thrombus, and guide it into the catheter sheath or an aspiration catheter for removal from the body. These devices include balloon catheters that are designed to be pushed through the thrombus, inflated, and withdrawn to pull the thrombus into the removal catheter. Other devices are designed to entangle or otherwise capture the thrombus within the blood vessel using a corkscrew or spring/coil device, and then move the thrombus into the catheter sheath for removal.
The structure of a thrombus is complex and may include platelets, blood cells, and fibrin. Thrombi tend to have a hard and dense perimeter lying against the vessel wall, and a liquid or gelatinous core towards the center of the vessel lumen. Existing thrombectomy devices are inefficient or incapable of removing the entirety of a thrombus. For example, aspiration catheters may remove the softer, central portions of the thrombus, thereby partially restoring vessel patency, but may not provide enough suction to dislodge the dense perimeter portions of the thrombus. The mechanical capture devices that entangle or snare a thrombus may be effective at removing relatively dense thrombi but are incapable of gaining purchase on softer thrombi while increasing the risk of embolism. Further, as these mechanical devices are moved proximally along a vessel in order to collect a thrombus, the denser perimeter portions of the thrombus may force the device to decrease in diameter. This may cause the mechanical device to not only fail to collect the softer thrombus, but also a portion of the harder thrombus adjacent to the vessel wall. is the relative inefficiency of collection may necessitation repeated retriever pulls and even then may result in incomplete thrombus removal. Thus, there is a need for a retriever that is capable of efficiently removing the entirety, or nearly the entirety, of a thrombus in a single pull, while minimizing the risk of embolism.
The invention provides a thrombus retriever and associated methods of use. The thrombus retriever generally may consist of a retriever body, a mesh covering at least the distal end of the retriever body, a centrally-disposed deployment member, and a centrally-disposed collecting member; the latter two elements being under independent operator control. The retriever body is attached through leading arms to the deployment member at a point that is more distal than the distal-most edge of the retriever body, thereby pulling the device from its distal edge thus directing it towards the vessel wall resulting in more complete collection of thrombus. The thrombus retriever is designed and adapted to be housed in, and deployed from an intravascular catheter. Accordingly, the thrombus retriever and, particularly the retriever body, is capable of adopting a crimped conformation (e.g., when loaded into a catheter) and a deployed conformation (e.g., when deployed within a blood vessel for thrombus collection). The crimped conformation, therefore, has a smaller diameter or width than the deployed conformation. Various embodiments and features of the thrombus retriever are described below.
In one aspect, the invention provides a thrombus retriever having:
In another embodiment, the retriever body also has two or more leading arms extending from the proximal end of the retriever body and that are connected to the collecting member. Optionally, each of the leading arms is attached to the collecting member by one or more flexible wires.
In some embodiments, the third diameter is greater than, or substantially the same as the first diameter.
In a second aspect, the invention provides a thrombus retriever having:
In one embodiment of any of the thrombus retrievers described above, the retriever body comprises one or more first circumferential bands having loops forming a generally sinusoidal or zig-zag pattern around the circumference of the retriever body.
In another embodiment of any of the thrombus retrievers described above, the retriever body comprises one or more second circumferential bands having loops forming a generally sinusoidal or zig-zag pattern around the circumference of the retriever body. The first circumferential bands and the second circumferential bands may have the same or different generally sinusoidal patterns. Optionally, the loops of the one or more first circumferential bands are out of phase with the loops of the first circumferential bands. Optionally, the arms of the sinusoidal ring between loops is sigmoidal rather than straight in order to allow a smaller and denser crimped diameter.
In a third aspect, the invention provides a thrombus retriever having:
In one embodiment, the retriever hoop plane is canted at an angle of 0°-45° (e.g., about 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°) relative to the deployment member or the longitudinal axis or lumen wall of the blood vessel in which the retriever is deployed.
In another embodiment, the retriever hoop is a ribbon having a proximal edge and a distal edge, wherein the distal edge is medially-disposed relative to the proximal edge such that the ribbon forms a canting angle of 135°-180° (e.g., about 135°, 140°, 145°, 150°, 155°, 160°, 165°, 170°, 175°, or 180°) to allow it to plow into the denser thrombus close to the vessel wall.
In some embodiments of the thrombus retrievers described herein, the retriever body is self-expanding. In some embodiments, the crimped conformation of the retriever body has a diameter of 1-5 French (e.g., 2-4 French). In some embodiments, the deployed conformation of the retriever body has a diameter of 3-12 French (e.g., about 3, 6, 9, or 12 French).
In other embodiments of the inventive thrombus retrievers, the retriever body is attached to the deployment member by two or more (e.g., three, four, five, six or more) distal arms. The distal arms are attached to the retriever body on their proximal ends and to the deployment member on their distal ends, thereby extending from the distal end of the retriever body and thereby serving to push the retriever body from behind when it is pulled through the thrombus. The distal arms may be fabricated as separate pieces and attached to the retriever body and deployment member (e.g., by welding). Alternatively, the distal arms may be fabricated as elements contiguous with either the retriever body or the deployment member. Optionally, the distal arms, by pushing the retriever body from behind, exert an outwardly-directed force on the retriever body, pushing it towards the vessel wall. Such outward force provides a bias for the retriever body toward the vessel wall (i.e., toward a larger-diameter conformation) to secure more complete retrieval of dense thrombus at the vessel wall.
In other embodiments of the inventive thrombus retrievers, the deployment member is a rigid or semi-rigid wire.
In other embodiments of the inventive thrombus retrievers, the collecting member is a tube comprising a lumen. Optionally, the deployment member is a rigid or semi-rigid wire that passes through the lumen of the tubular collecting member.
In some embodiments of the inventive thrombus retrievers, the net or mesh is a woven net, a perforated membrane or a non-woven mesh of polymer fibers. bursiform.
In other embodiments, any portion of thrombus retriever is made from a shape-memory material including, for example, shape-memory metals. In some embodiments, the shape-memory metal is nickel titanium (“NiTi” or nitinol).
In another aspect, the invention provides a thrombus retrievers described herein, in a crimped conformation, housed within the lumen of an intravascular catheter. In some embodiments, the catheter is a microcatheter (e.g., having a lumen diameter of 2 French or 3 French).
In another aspect, the invention provides a method for retrieving or removing a thrombus from a blood vessel of a subject (e.g., a human subject). A thrombus retriever described herein is provided, wherein the retriever body is in a crimped conformation and housed within the lumen of an intravascular catheter. The deployment member and the collecting member are independently controlled by the operator (e.g., interventional cardiologist, radiologist or neuro-radiologist). The catheter is pushed in the distal direction through the target thrombus until the catheter lumen opening is positioned across the distal side of the thrombus.
The thrombus retriever then is deployed. In one embodiment, the thrombus retriever is deployed by withdrawing the catheter sheath in the proximal direction while maintaining the deployment member in a fixed position, thereby maintaining the thrombus retriever on the distal side of the target thrombus. In another embodiment, the thrombus retriever is deployed by first displacing it from the catheter by pushing the deployment member in the distal direction while maintaining the catheter in a substantially fixed position relative to the blood vessel. After deployment, the catheter sheath is withdrawn in the proximal direction while maintaining the deployment member in a substantially fixed position. After retriever deployment, the catheter sheath is maintained on the proximal side of the target thrombus, optionally within less than 10 mm, less than 20 mm, or less than 30 mm of the target thrombus. Optionally, the retriever body is self-expanding and expands simultaneously upon withdrawal of the catheter sheath. Alternatively, the retriever body can be expanded by a balloon. After expansion, the balloon can be deflated and withdrawn through the lumen of the collecting member.
The operator then pulls the deployment member in the proximal direction until the retriever body traverses the target thrombus and retrieve the thrombus into the net. Preferably, the catheter sheath remains stationary.
In one embodiment, the operator then pulls the collecting member in the proximal direction sufficient to bring the retriever body into a crimped or partially crimped conformation such that the retriever body is conformed to be collected into the catheter lumen. The deployment member and the collecting member are then simultaneously pulled in the proximal direction such that the retriever body is maintained in the crimped or partially crimped conformation and also is translocated to a position within the catheter lumen, thereby restoring the retriever body to a crimped conformation and collecting the thrombus into the catheter.
In another embodiment, the collecting member and the deployment member are pulled simultaneously in the proximal direction with the collecting member being pulled to a greater extend (i.e., being proximally-translocated relative to the deployment member) such that the retriever body is simultaneously brought into a crimped or partially crimped conformation and translocated in a proximal direction.
Following collection of the retriever body and collected thrombus into the catheter lumen, the operator withdraws the catheter from the subject.
“Proximal” is a relative term that refers to the direction or side towards the operator and the entry point of the catheter into the vessel. For example, an operator withdrawing a catheter from a patient is translating the catheter in the proximal direction. Likewise, the side or face of a thrombus first encountered by a catheter during insertion of the catheter across the thrombus, is the proximal side.
“Distal” is a relative term that refers to the direction or side away from the operator and the entry point. For example, an operator inserting a catheter into a patient is translating the catheter in a distal direction.
The invention generally provides a thrombus retriever that is collapsible within, and is delivered by, an intravascular catheter. The retriever generally has a proximal end and a distal end. In some embodiments, a retriever body is connected to a deployment member (e.g., a central wire or other longitudinal backbone) that is under operator control and is adapted to translocate the retriever body longitudinally within the blood vessel lumen in order to collect the target thrombus. The retriever body is affixed to the deployment member such that pulling the deployment member in the proximal direction effectively “pushes” the retriever from behind (i.e., the distal end) in that proximal direction while generating a bias force outwardly that tends to push the retriever closer to the vessel wall for optimal collecting of dense thrombus attached to the vessel wall. In some embodiments, the retriever body is affixed at its distal end to the deployment member in order to generate the pushing force. In some embodiments, the retriever body also is connected to a collecting member (e.g., an inner tube) that is under operator control and is adapted to cause the retriever body to reenter the catheter with the collected thrombus and resume a crimped conformation once thrombus collection is complete. Generally, the collecting member is pulled in a proximal direction, applying tension to collecting wires attached to the retriever body. The collecting wires are configured to cause a reduction in the retriever body diameter to facilitate reentry of the retriever body and collected thrombus into the catheter lumen. In other embodiments, the retriever body and the collecting wires are attached to a common longitudinal backbone that facilitates both longitudinal translocation of the retriever within the vessel lumen and recovery of the retriever body within the catheter lumen after thrombus collection is complete. Various embodiments of the thrombus retriever are described in more detail below. The description of common elements in the context of one embodiment are equally applicable to other embodiments having those same or similar elements.
The three major improvements of the thrombus retrievers described herein are: (a) the retriever body is pushed from behind by the arms generating bias towards the vessel wall as opposed to a bias away from the wall in state of the art thrombus retrievers that are pulled from the front; (b) the cross-section of the frame is canted such that additional bias is created towards the vessel wall; and (c) the collecting net at the distal end of the retriever body for collecting the thrombus. Improvement (a) and (b) improve the efficiency of collecting hard thrombus next to the vessel wall and improvement (c) improves the collection of a soft thrombus and thrombus fractures to prevent emboli.
In use, the operator pulls the central wire 110 in the proximal direction (arrow), causing the retriever body 130 to be translocated in the proximal direction. The pulling force applied by the operator is transferred from the central wire 110 to the retriever body 130 via the distal arms 120. The transfer of force causes the distal arms 120 to apply a slight outward (radial/lateral) pressure to the retriever body 130 which tends to maintain the retriever body pushed against the inner wall of the vessel 10. The retriever body 130 therefore tends to scrape the hard and dense portions of the thrombus perimeter from the inner wall of the vessel 10 as it is moved in the proximal direction. The retriever 100 and the thrombus and debris retained therein are collected into the catheter and removed from the body. Additional features of retriever 100 are described in more detail below.
Optionally, the arms of the sinusoidal ring between loops is sigmoidal rather than straight in order to allow a smaller and denser crimped diameter.
The retriever body 130 may be constructed of known materials, and for example stainless steel or cobalt chromium, but it is particularly suitable to be constructed from shape memory alloys such as NiTi. The pattern can be formed by laser cutting or etching a tube or flat sheet of material into the pattern shown. A flat sheet may be formed into a retriever body 130 by rolling the etched or laser cut sheet into a tubular shape, and welding the edges of the sheet together to form the tubular retriever body 130. The details of this method of forming the retriever body 130 are substantially the same as may be used to form intravascular stents and are disclosed in U.S. Pat. Nos. 5,836,964 and 5,997,703, each of which is hereby incorporated by reference in its entirety. Other methods known to those of skill in the art such as laser cutting a tube or etching a tube may also be used to construct a retriever body 130 in the present invention. When NiTi or certain other memory shape alloys are used, the retriever body 130 is heat treated after formation into a tubular shape, as known by those skilled in the art, to take advantage of the shape memory characteristics and/or super elasticity.
The foregoing pattern of struts 131 and fenestrations 134 is not intended to be limiting. Any suitable pattern of struts 131 and fenestrations 134 may be used. For example, wire frame retriever body 130 may have any pattern used to construct intravascular stents including, for example, the patterns disclosed in U.S. Pat. Nos. 6,197,048, 6,355,059, and 7,033,386, and U.S. Patent Publication 2012/0283817, each of which is hereby incorporated by reference. Furthermore, the retriever body 130 is illustrates has having two rows of struts 131 forming one row of fenestrations 134. This design choice is not limiting. A retriever body 130 may be constructed by increasing the number of rows of struts 131 and fenestrations 134, thereby forming a longer cylinder. The retriever body 130 cylinder formed by the struts 131 is open on its proximal and distal ends, notwithstanding the mesh covering 135 described in more detail below.
In one specific embodiment, the retriever body 130 is longitudinally translocated within the vessel lumen and deployed/pulled for thrombus retrieval using two separate elements, each under independent control of the operator. The first element is a deployment member (e.g., a longitudinal backbone), exemplified in this embodiment as deployment member 111. The deployment member generally serves to longitudinally translocate the retriever body 130 within the vessel lumen and/or catheter lumen, either in the crimped or deployed conformation. The retriever body 130 is rigidly attached to the deployment member and pulling the deployment member by the arms 120 in the proximal direction provides the motive “pushing” force on the distal side of the retriever body 130. Thus, the deployment member 111 is sufficiently rigid to accommodate that application of force. It is understood that, although exemplified as deployment member 111, the deployment member 111 need not be a tube and instead may be any suitable structure or shape such as a wire.
The second retriever body 130 control element is the collection member which is adapted to cause the retriever body to return to a crimped conformation from the deployed conformation once thrombus collection is complete. The collection member is under independent operator control and is functionally connected to the retriever body 130 by flexible wires 133 and collecting arms 132. The collection member is illustrated below as tube 140 and having the deployment member 111 disposed through its lumen. However, this configuration is not intended to be limiting. For example, the collection member may be a second rigid wire and wherein both the deployment member and the deployment member are independently disposed within the catheter lumen.
In the embodiment illustrated in
The distal arms 120 may be attached to the translocating member 111 in any appropriate manner. In some embodiments, the plurality of distal arms are attached to the same attachment point 115 on the deployment member 110 or to different (a plurality of) attachment points 115. For example, for embodiments in which at least two of the plurality of distal arms 120 have different lengths, a shorter distal arm 120 is attached to the deployment member at a first attachment point 115 that is closer to the retriever body 130, but still distal relative to the distal edge of the retriever body 130, and a longer distal arm is attached to the deployment member at a second attachment point 115 that is more distal on the deployment member 110 than the first attachment point 115.
Distal arms 120 may be permanently attached to the deployment member 110 by any suitable means. For example, the distal arms 120 may be fabricated as separate elements and welded at the attachment point and onto the retriever body 130. Alternatively, distal arms 120 may be fabricated as a contiguous component of either the deployment member 110 or the retriever body 130, and connected to the other component.
Leading arms 132 are rigid or semi-rigid struts attached at their distal ends to the proximal edge of the retriever body 130 and project in a direction that is substantially parallel to the central axis of the cylindrical retriever body 130. The leading arms 132 may be constructed of the same or different material as the retriever body 130, and may be integral to the retriever body 130 during fabrication or individually attached as separate elements. In one embodiment, the leading arms 132 extend from the proximal peaks 136 of the retriever body 130. In one embodiment, each proximal peak 136 has an attached leading arm 132. Optionally, leading arm 132 are adapted to have a connection point for wires 133 such as an eyelet or any other form.
Wires 133 are adapted to transition the retriever body 130 from the deployed to the crimped or collected conformations. Wires 133 preferably are arranged in a 1:1 relationship with leading arms 132, but other conformations are possible (e.g., two wires 133 are attached to each leading arm 132). Wires 133 are attached at their distal end to the proximal end of the leading arms 132 and at their proximal end to the inner tube 140. Attachment of wires 133 to inner tube 140 may be on the exterior surface, interior lumen, or distal edge of the inner tube 140. The wires 133 may be formed of any suitable material that is both flexible and capable of sustaining the force necessary to close the retriever body 130 from the deployed conformation to at least a partially-crimped conformation for collection. The wires 133 may be formed from a metal (e.g., NiTi) or a thermoplastic polymer, for example.
The inner tube 140 is sized to fit within the catheter lumen 35. In one embodiment, the outer diameter of inner tube 140 is slidingly fit into the inner diameter of the catheter lumen 35, thereby maximizing the cross-sectional area of the inner tube 140. The inner tube 140 may be made of any suitable material including, for example, metal or thermoplastic polymers or combination of polymer and metal braiding. Alternatively, the outer diameter of inner tube 140 is small enough to fit within the lumen of the retriever body 130 in the crimped conformation.
The principles of the construction and features of the thrombus retriever 100 are further illustrated by describing its operation. The thrombus retriever 100 is first placed in its crimped conformation. The thrombus retriever 100 is then loaded into the lumen 30 of an intravascular catheter 30 while the inner tube 140 and central wire 110 (or element 111) are held in a fixed relationship to each other. Optionally and if necessary, the inner tube 140 is move in the distal direction to relieve tension on the wires 133. This will allow the retriever body 130 to expand and adopt the deployed conformation immediately and automatically upon its exit from the catheter lumen 35.
The loaded catheter 30 is inserted into the patient's body in the standard manner (e.g. through the radial artery) and guided to the site of the target thrombus 20. The catheter 30 is pushed through the thrombus 20 until the catheter lumen 35 is across the thrombus. The thrombus retriever 100 is deployed on the distal side of the thrombus 20. In one embodiment, the thrombus retriever 100 is deployed by pushing the deployment member (e.g., central wire 110 or deployment member 111) in the distal direction while the catheter 30 sheath is maintained in a substantially fixed position relative to the blood vessel 10. After deployment, the catheter 30 sheath then is withdrawn to the proximal side across the thrombus 20 location retrieving the thrombus. In another embodiment, the retriever 100 is deployed on the distal side of the thrombus by withdrawing the catheter 30 sheath to the proximal side of the thrombus while maintaining the retriever body 130 in a substantially fixed position relative to the blood vessel 10 (i.e., by sliding the catheter 30 in the proximal direction relative to the deployment member 110 or 111.
After the thrombus is retrieved (i.e., after the retriever body 130 has been translocated in the proximal direction to traverse all or a portion of the thrombus 20 to be retrieved), the inner tube 140 is pulled in the proximal direction to collect the retriever body and the thrombus into the catheter 35.
It is understood that the retriever body 130 may be returned only to a partially crimped conformation by the proximal pulling action of the inner tube 140 on the wires 133 during the retrieval process. To effect retrieval, it is sufficient for the pulling action of the inner tube 140 and wires 133 to translocate the leading arms 132 toward the central axis enough that the proximal ends of the leading arms 132 form a diameter smaller than the diameter of the catheter lumen 35, even if the retriever body 130 is not collapsed into its fully crimpled conformation. From this partially-crimped conformation, the proximal ends of the leading arms 132 may be pulled in the proximal direction, using the inner tube 140 and the central wire 110, so that the ends are disposed within the catheter lumen 35. Once so disposed, the remainder of the retriever apparatus 100 can be pulled in the proximal direction into the catheter lumen 35, completing the transition into the fully collected conformation.
In use, catheter 30 is pushed through the thrombus 20 until the catheter lumen 35 is across the thrombus. The thrombus retriever 300 is deployed on the distal side of the thrombus 20. In one embodiment, the thrombus retriever 300 is deployed by pushing the actuator 340 in the distal direction while the catheter 30 sheath is maintained in a substantially fixed position relative to the blood vessel 10. After deployment, the catheter 30 sheath then is withdrawn to the proximal side of the thrombus 20. In another embodiment, the retriever 300 is deployed on the distal side of the thrombus by withdrawing the catheter 30 sheath to the proximal side of the thrombus while maintaining the retriever body 130 in a substantially fixed position relative to the blood vessel 10 (i.e., by sliding the catheter 30 in the proximal direction relative to actuator 340). In the deployed conformation, wires 333 should not be deflected by the distal edge 31 of catheter 30. Thrombus collection is achieved by pulling actuator 340 in the proximal direction to collect the thrombus 20 in the mesh covering.
After collection of the target thrombus, retriever body 330 is recovered into the catheter lumen 35 by a further translocation of actuator 340 in the proximal direction. Wires 333 become deflected by the distal edge 31 of catheter 30 as retriever body 330 nears the distal opening of catheter lumen 35. This proximally-directed translocation of retriever body 330 relative to catheter 30 causes wires 333 to inwardly defect leading arms 332, thereby reducing the diameter circumscribed by the proximal ends of leading arms 332. Continued proximal translocation of actuator 340, through the crimping action of wires 333 on leading arms 332, draws the proximal ends of leading arms 332 within the catheter lumen 35. Further proximal translocation of the actuator 340 then pulls the retriever body 330 fully within the lumen by the concomitant application of force through the attachment point 315 and distal arms 320, thereby collecting the retriever body 330 and collected thrombus within the catheter lumen 35.
Net 235 is attached to retriever body 230 and, in the deployed conformation, extends in the distal direction. Net 235 may have any suitable shape and dimension designed to accommodate the volume of the thrombus to be retrieved and that is capable of being collapsed into a crimped conformation and delivered/deployed from an intravascular catheter. The central wire 210 may pass through the net or on its side. The optional attachment of net 235 to central wire 210 is generally located in the distal portion of net 235 and preferably at its most distal point or face. Optionally, net 235 is attached to attachment point 215.
A plurality (e.g., three, four, five, six, or more) of distal arms 220 are attached at their proximal end to the distal edge of retriever body 230 and at their distal end to the central wire 210 at attachment point 215. Distal arms 220 may be attached to the same or different attachment points 215. For example, as illustrated in
For collection of retriever 200 into the catheter following thrombus collection, collecting wire 233 is tightened by translocating the inner tube 240 in the proximal direction relative to central wire 210 and catheter 35 until retriever body 230 is withdrawn into lumen 35 by translocating inner tube 240 (see,
It will be appreciated by persons having ordinary skill in the art that many variations, additions, modifications, and other applications may be made to what has been particularly shown and described herein by way of embodiments, without departing from the spirit or scope of the invention. Therefore it is intended that scope of the invention, as defined by the claims below, includes all foreseeable variations, additions, modifications or applications.
This application claims priority to the U.S. provisional patent application Ser. No. 62/395,217, filed Sep. 15, 2016. Priority to the provisional patent application is expressly claimed, and the disclosure of the provisional application is hereby incorporated herein by reference in their entireties and for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2017/001225 | 9/5/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62395217 | Sep 2016 | US |
