Patent Application
20220054150
Many diseases result from the presence of undesirable material, most notably clots or thrombus, in blood vessels and heart chambers. Clots within vessels can be formed from blood cells, collagen, cholesterol, plaque, fat, calcified plaque, bubbles, arterial tissue, aggregates of proteins (e.g., fibrin), and/or other miscellaneous fragments or combinations thereof. Clots can lodge, for example, in narrow regions of blood vessels that feed the major organs, and therefore, cause loss of oxygen-rich blood flow to surrounding tissues resulting in localized cell death or micro-infarcts. Cerebral micro-infarcts can cause stroke leading to confusion, disturbance of speech, paralysis, visual disturbances, balance disturbances and even death. In the heart, clots can cause myocardial infarcts, i.e., heart attacks. If the clots are left untreated, they are potentially life threatening, and therefore, the presence of clots in the blood vessels need immediate medical intervention.
Clots can typically be treated or eliminated by utilizing biologic intervention, surgical intervention, or a combination of the two. Biologic treatments involve the delivery of agents directly to the clots by a catheter to either dissolve or at least stabilize it until the body can eliminate it. However, the disadvantage of treating clots with biologic agents is that they expose much of the body to the agents, potentially leading to life-threatening bleeding complications.
Alternately or additionally, mechanical means can be used to remove the clots from a patient's vessel. Mechanical treatments typically involve aspiration, maceration, and compression of the clots within the vessel and finally removing it either by invasive surgery or by non-invasive means, such as with an aspiration catheter connected to an aspiration source (e.g., pump or syringe). The distinct advantage of invasive or non-invasive mechanical treatment is that it directly attacks the clots and eliminates the vascular obstruction without affecting non-diseased areas of the body, unlike biologic agents.
The mechanical, non-invasive clot removal treatments generally relate to thrombectomy procedures, more particularly, peripheral thrombectomy procedures and venous thrombectomy procedures, such as deep venous thrombosis (DVT) treatment or intracranial distal aspiration.
Acute ischemic stroke treatment using vascular aspiration embolectomy involves aspiration techniques to draw clots into a catheter via suction and has been proven to be as effective as mechanical thrombectomy using stent retrievers which deploy self-expanding stent-like capture devices to capture and removed the thrombus. Aspiration embolectomy has gained favor with a major section of the neuro-interventional physicians due to the ease of procedure and its cost effectiveness.
In aspiration embolectomy, a distal aspiration catheter (DAC) is used to remove the clot or emboli from the vessel. At the first step of the procedure, a distal end of the catheter is positioned adjacent to the clot and then a vacuum force is applied through a lumen in the catheter using a pump or large volume syringe. The suction force used by the syringe or pump partially ingests or pulls in the emboli into the distal portion of the DAC. In such instances, when the emboli are partially ingested, repeated passes of the device may be needed to recanalize the vessel.
Successful clinical outcome of the patients undergoing aspiration embolectomy, however, depends on the “first-pass effect”. The first-pass effect is defined as the complete or near-complete recanalization of the affected vessel after one pass of an embolectomy device by complete removal of the emboli in the first attempt.
Inside the vessels, however, blood clots can undergo a process called organization where the soft gel-like red/purple clot is transformed into a firmer, whitish clot by the cross-linking of proteins such as fibrin. Clots may also form firm masses with the forward pressure of blood flow over time. Firm clots can form a large mass of well embedded, mature clots over time which are less flexible and can be difficult to completely ingest into the traditional DAC when suction is applied with the attached pump or aspiration syringe kit. This partial ingestion of thrombus/emboli using a traditional DAC, therefore, reduces the chances of a first pass effect and requires additional passes of the traditional DAC for complete removal of thrombus/emboli. Additionally, there is also the possibility of fragmentation of the well embedded, mature thrombus/emboli during removal which can travel to other areas in the blood vessels. The above risk factors for removing a large mass of well embedded, mature clots by using a traditional DAC negatively impacts the clinical outcome of a patient by reducing the chance of a “first pass effect”.
Furthermore, the use of a stent retriever in combination with a traditional DAC, known as the Solumbra technique, has become a popular approach to mechanical thrombectomy for acute ischemic stroke. However, the Solumbra technique has not been shown to improve the first pass effect over aspiration embolectomy alone.
Hence, there is a need for an advanced DAC which can at least overcome the problems discussed above for use of a traditional DAC, particularly for removing well embedded, mature clots and improving the clinical outcome in patients by complete recanalization of the vessel after one pass of the DAC device.
The present invention is directed to an aspiration catheter and method of use which can be used to fatigue a clot so that it can be completely removed from a blood vessel. These devices and methods may be particularly helpful for firm and/or well-embedded clots that might otherwise present difficulties during a removal process. In some instances, these embodiments and methods can lead to recanalization of the blood vessel after one pass of the catheter.
In one embodiment, the aspiration catheter comprises a catheter body. The catheter body further comprises a first lumen located within the catheter body and opening at a distal end of the catheter body. The first lumen is configured for connection to an aspiration source. The aspiration catheter further comprises a second lumen opening within a distal region of the first lumen and at a proximal region of the catheter body. An elongated mandrel is positioned within the second lumen and is configured to move into the first lumen so as to fatigue a clot at least partially positioned within the first lumen.
In some embodiments, a distal portion of the elongated mandrel is configured to move into the first lumen to fatigue the partially positioned clot within the first lumen. According to some embodiments, the distal portion of the elongated mandrel is configured to move translationally and/or rotationally to fatigue the partially positioned clot within the first lumen.
In some embodiments, a stiffness of the catheter body gradually reduces from the proximal region of the catheter body to a distal region of the catheter body. In some embodiments, a length of the distal region of the catheter body comprises a hydrophilic coating to reduce friction with a targeted vessel lumen during the navigation of the catheter inside the blood vessel.
According to some embodiments of the present invention, a method of removing a clot from a blood vessel of a patient comprises a first step of navigating a catheter comprising a lumen over a guidewire inside the blood vessel such that a distal end of the lumen of the catheter is engaged with a surface of the clot. Next, an aspiration source attached to a proximal end of the lumen of the catheter is activated and the clot is partially ingested into the distal end of the lumen of the catheter. A mandrel, positioned in the distal portion in catheter lumen, is moved into the partially ingested clot to fatigue the clot. The fatigued clot is completely aspirated from the blood vessel with one pass of the catheter.
In some embodiments, the step of moving the mandrel into the partially ingested clot to fatigue the clot further comprises moving the mandrel rotationally and/or translationally into the partially ingested clot to fatigue the clot.
These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which:
Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.
The terms clot, thrombus, and embolus are used interchangeably within this specification. Generally, these terms mean a mass or connected group of blood cells, collagen, cholesterol, plaque, fat, calcified plaque, bubbles, arterial tissue, aggregates of proteins (e.g., fibrin), and/or other miscellaneous fragments or combinations thereof.
As previously discussed, existing aspiration catheter techniques may not be effective in removing large amounts of firmly embedded clot from inside a blood vessel after one pass of the aspiration catheter because of a lack of complete ingestion of the clot inside the aspiration catheter and/or fragmentation of the clots during removal.
If the clot 10 is firmly embedded and larger than the diameter of the DAC 20, applying vacuum force alone may not be effective in recanalization of the vessel. In other words, complete removal of the clot after a first pass of the device may not be possible. While it may be possible to use a larger diameter DAC and/or apply a stronger vacuum force, a larger profile DAC can be more challenging to navigate to achieve distal intracranial circulation and may be detrimental to the vessel lumen, causing dissection/vasospasm.
The present invention seeks to address the deficiencies of the existing devices and techniques by removing a clot after one pass of a DAC during a procedure. Some of the embodiments described herein are directed to a DAC (also referred to more generally as a catheter) that includes a mechanism for causing clot fatigue. More specifically, a DAC includes a mechanism for creating physical stress to a clot in a way that reduces the hardness, size, and/or cohesion of the clot. This stress can be achieved with mandrels, cutting devices with sharp and/or dull blades, or similar components that are configured to move relative to the clot.
The term “clot fatigue” is generally defined as a process to apply mechanical stress to a clot to alter/reduce stiffness, size, and/or cohesion to cause the clot to partially or completely break down. Performing procedures to fatigue a clot can be particularly helpful for aspirating a clot into a catheter and removal from a patient.
The DAC can be used to remove clots/emboli from any kind of blood vessels. Vessels from which the clot/emboli may be removed, in accordance with an embodiment of the present invention, include acute ischemic stroke, those within the pulmonary circulation (e.g., pulmonary arteries), systemic venous circulation (e.g., jugular vein, sigmoid sinus, transverse sinus, superior and inferior sagittal sinus, vena cava, pelvic veins, femoral veins, and subclavian veins), or arterial circulation (e.g., aorta or its large and medium branches).
Some embodiments of the DAC of the present invention comprises a plurality of protruding structures, for example, mandrels, at a distal portion in a lumen of the DAC. Upon engaging the clot with the distal end of the DAC, the distal portions of the protruding structures can undergo rotational and/or translational motion to induce “clot fatigue” which helps the clot to be partially or completely ingested inside the lumen of the DAC by the application of a vacuum force.
The mandrels 140, 150 can be engaged or activated upon engagement with the clot. Depending on the positioning and configuration of the mandrels 140, 150, this may involve initially applying aspiration to the catheter 100 to at least partially draw the clot near the distal end of the DAC 100 and preferably within the aspiration lumen 101 of the DAC 100. However, it is possible that the mandrels 140, 150 can be configured to fatigue or stress the clot without the need for initial aspiration, such as by being configured to extend to a very distal edge of the DAC 100 or even slightly beyond the distal end of the DAC 100.
Generally, the mandrels described in this specification are bodies having an elongated shape with a length sufficient to extend between a proximal portion and a distal portion of the DAC 100. The mandrels preferably have at least some rigidity sufficient to allow distal and proximal movement through passages in the DAC 100. For example, the mandrels may be composed of wire alone, coated wire, a helical wire coil, or similar arrangements. The mandrels may be generally similar to known guidewire designs, and in some circumstances, guidewires can be used as mandrels.
As illustrated in
The DAC 100 may include a tubular catheter body having a stiff proximal shaft. The stiffness of the proximal shaft helps to attach the proximal end 120 of the DAC 100 with a handle 200 (
In some embodiments, the DAC 100 comprises a lumen 101 having a proximal section 102 and a distal section 104. The lumen 101 may have a range of different sizes, depending on the location of use within a patient, such as a diameter in a range of about 6-8 French.
In some embodiments, a hydrophilic coating is disposed on an outer portion of the distal section 104 of the DAC lumen. The hydrophilic coating is used to reduce friction with the vessel lumen during navigation of the DAC 100 inside the distal sections of the intracranial blood vessels. In one example, about 60 centimeters of the distal portion of the DAC lumen 104 comprises hydrophilic coating to reduce friction with the vessel lumen during the navigation. In another example, about 30 centimeters of the distal portion of the DAC lumen 104 comprises a hydrophilic coating to reduce friction with the vessel lumen during the navigation. In yet another example, about 20 centimeters of the distal portion of the DAC lumen 104 comprises a hydrophilic coating to reduce friction with the vessel lumen during the navigation. In some embodiments, the hydrophilic coating comprises but is not limited to commercial coating solutions such as Hydak, which is a curable UV and heat treatment (Biocoat, Horsham, Pa.), or Lubricent, which is a curable UV treatment (Harland Medical Systems, Eden Prairie, Minn.).
The DAC 100 also includes a passage or channel for each mandrel that extends between a proximal end of the DAC 100 and a distal end of the DAC 100. These passages or channels generally have a distal opening through which the mandrel can be positioned out of and a proximal opening through which the mandrel can extend from (e.g., for manual actuation or into a motorized handle for motorized actuation). In some embodiments, each of the channels are configured to carry one mandrel, though larger diameter channels configured to carry multiple mandrels are also possible. Channels and their distal openings can be positioned at different circumferential locations relative to each other. For example, two channels may be located at about 180 degrees relative to each other (i.e., opposite diametric positions), 90 degrees relative to each other, 45 degrees relative to each other, 25 degrees relative to each other, or any angle and/or angle combination.
The positions of the channels along the periphery I of the DAC 100 (e.g., within the wall or between wall layers of the DAC 100) may have several advantages. First, this arrangement can accommodate a relatively large number of channels while maintaining a sufficient size of the aspiration lumen 101. In one example,
Another advantage of the peripheral positions of the luminal channels and mandrels is that the mandrels do not obstruct the passage of the thrombus inside the lumen 104 of the DAC 100 and therefore increases the chance of the first pass effect. While placing one or more mandrels through the aspiration lumen 101 is possible according to the present invention, their potential blockage of the clot makes the use of the described channels preferable.
Similarly, the second luminal channel 170 comprises a first port 172 at the distal portion of the DAC 100 and a second port 174 at the proximal portion of the DAC 100. A second mandrel 150 is positioned within a lumen of the second luminal channel 150 so that its distal portion 152 extends out of the distal first port 172 and its proximal end 156 extends out of the proximal second port 174.
The proximal second ports 164, 174 can be positioned in a proximal location opening on the outer surface of the DAC 100 so that they can be used similar to a rapid exchange port and allow for manual actuation by a user. Alternately, the proximal second ports 164, 174 can open within a catheter hub in a manner that allows manual actuation by the user. Alternately, the proximal portions may open directly into a handle to allow for motorized actuation, as discussed with regard to further embodiments later in this specification.
Although, two channels 160 and 170 are illustrated in
The distal first ports and/or the distal portions of the mandrels (e.g., first ports 162, 172, distal portions 142, 152, and mandrels 140, 150) can be configured to direct the distal portion of the mandrels into the main aspiration lumen 101 of the DAC 100 at different angles relative to the axis of the DAC 100. For example, the distal portion of a mandrel can be configured to exit the first port in an angle generally parallel to the axis of the DAC 100 (e.g., as shown in
The angle of exit from the first port can be achieved in several different way. First, the first port itself can be curved to direct the mandrel out at a specific angle. Second, at least the distal portion of the mandrel can be composed of a shape memory material that has a memory shape or heat-set shape that causes it to bend when unconstrained. Either or both of these techniques can be used.
In some embodiments of the present invention, to ensure “clot fatigue”, the mandrels can be moved translationally (i.e., proximally and distally), rotationally relative to an axis of the mandrel, or a combination of the two. Additionally, multiple mandrels may have the same movement characteristics or different movement characteristic. For example, one mandrel may rotate while another mandrel moves translationally. In another example, one mandrel may distally extend and remain stationary while the other mandrel moves translationally.
In one example, the translational movement may consist of a mandrel moving proximally and distally by about 0.5 to 5 mm. In another example, the translational movement can cycle back and forth relatively slowly (e.g., about once every 1 to 2 seconds) or relatively quickly (e.g., about once every 0.5 to 0.01 seconds). In another example, the rotational movement of a mandrel can continuously rotate in a single direction or can rotate back and forth, switching directions periodically.
Returning to the DAC 100 example of
In one specific example technique shown in
The distal portions (e.g.,142 and 152) of the mandrels (e.g.,140 and 150) described in this specification can have a variety of different shapes to help penetrate or break up the structure of a clot. For example, the mandrel ends may form a point, a flattened rectangular shape, a triangular shape, a partial cylindrical shape, or similar variations.
In some embodiments of the present invention, the mandrels (e.g., 140 and 150) may be made of shape memory materials e.g., nitinol, stainless steel, or cobalt-chromium. Additionally or alternatively, the mandrels may be made of radiopaque materials, for example, platinum or tantalum. In some embodiments, the mandrels 140 and 150 have guidewire like flexibility so that they can be easily navigated through the first luminal channel 160 and the second luminal channel 170 of the DAC 100.
While the mandrels described in this specification can be custom made for the DAC 100, preexisting guidewires can also be used (e.g., a 0.035 inch guidewire).
Additionally, one of the channels 160, 170 can initially be used with a guidewire to initially position the DAC 100 at a desired clot location. For example, a guidewire can be initially positioned so that its distal end is near or within a target clot. A distal end of the guidewire can be placed into the distal first port 162 and into channel 160 until it extends out the second port 164. The DAC 100 can then be advanced over the guidewire until its distal end is located near the clot. Finally, the guidewire can be withdrawn and a mandrel 140 can be advanced into the channel 160, allowing the clot fatiguing and aspiration procedure to proceed accordingly.
As previously discussed, the translational and rotational motions of the mandrels can be performed manually in some embodiments. For example, a physician may grasp a proximal end of one or more mandrels and move them proximally/distally, as well as rotationally.
In other embodiments, the mandrels 140 and 150 may be moved via a motorized mechanism that converts the movement of an electric motor into the desired translational and rotational movement. As illustrated in the embodiment of
In some embodiments of the present invention, the distal portion 142 of the first mandrel 140 and the distal portion 152 of the second mandrel 150 do not protrude outside the distal end 110 of the DAC. For example, a mechanism to prevent movement outside of the DAC can be included, such as a hard stop or lip (not shown in the drawings) at the distal end 110 of the DAC 100 to prevent further distal movements of the distal portion 142 of the first mandrel 140 and the distal portion 152 of the second mandrel 150 outside the catheter lumen and into the blood vessels.
In an alternate embodiment, ‘clot fatigue” can be created by reducing the size of the clot by using one or more cutting elements located within a distal portion of the main lumen 101 of the DAC 100. The one or more cutting elements are generally defined as a structure comprising one or more cutting surfaces having a sharp, partially sharp, and/or dull surface that are sized, positioned, and/or configured to at least partially cut into a clot.
The cutting element can have a variety of different shapes, such as a flat planar shape, a point (e.g., surface 142A of
In some embodiments, the cutting element may be attached to or even integral with a distal end of a mandrel or similar structure so that it can be manually actuated in a manner similar to that described for the other mandrels in this specification. In other embodiments, the cutting element may be connected to a shaft or other elongated element that is configured for manual or motorized rotation. In other embodiments, the one or more cutting elements may be stationary by being fixed to an inner surface or other component within the lumen of the DAC 100 (e.g., a helical shape with an inner sharpened edge.
One method of removing a large and/or well embedded clot in the present invention is described below in connection with the previously described devices. A guidewire and/or delivery sheath may be initially deployed in the patient such that the guidewire or sheath allows a distal end 104 of the DAC 100 to be positioned near a clot. For example, the DAC 100 may be inserted into the targeted blood vessel over the guidewire and advanced towards the clot such that the distal end 110 of the DAC 100 is positioned against or near the surface of the clot 10.
Once the clot is positioned against or engaged with the distal end 110 of the DAC 100, an aspiration source connected to the DAC 100 is activated to at least partially suck the clot into the distal section 104 of the DAC lumen. Aspiration can be provided by a manually actuated syringe or motorized pump.
Next, “clot fatigue” is induced in the partially ingested clot either by manually operating the mandrels or by actuating an actuator such that the distal ends of the mandrels undergo translational and/or rotational motions into the clot (e.g.,
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
This application claims benefit of and priority to U.S. Provisional Application Ser. No. 63/068,684 filed Aug. 21, 2020, entitled DYNAMIC ASPIRATION CATHETER AND METHODS, which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63068684 | Aug 2020 | US |
