Cross Reference to Related Application

[0001] This application claims the priority of U.S. Provisional Patent Application Serial No. 62/941,175 filed on November 27, 2019, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

[0002] The present invention relates generally to medical and surgical devices and, more particularly, to devices, systems, and methods for removing blood clots during a catheter procedure.

Background

[0003] Stroke is a sudden and often severely debilitating medical event for many people. Stroke can cause sudden death, and even survivors can lose the ability to speak, walk, feed, and care for themselves. These patients frequently need long term care and have limited life expectancy.

[0004] The most common cause of a stroke is an obstruction of an artery in the brain caused by lodgement of a blood clot. The clot or embolus dislodges from a source such as the heart or an artery in the neck, and travels into a brain artery. As the artery narrows, the clot eventually becomes fixed or stuck in position. Flow ceases to the region of the brain beyond the obstruction and severe damage often occurs. The brain is very unforgiving of lost blood flow. Many regions are supplied by only one source of blood, and the function of the brain is not replicated. Once a motor or speech area is lost, there is limited ability for other segments of the brain to take over the lost function.

[0005] In the past, the typical treatment for stroke was conservative, watchful therapy. With this approach the outcome was often unsatisfactory. Another form of therapy involves the use of clot dissolving agents. However, these agents can only provide limited benefit.

[0006] More recently, important advances have occurred in catheterized blood clot removal techniques. Now, if stroke patients are brought to a catheterization laboratory (“oath lab”) promptly after the clot has lodged, the clot may be removed to more quickly restore blood flow. In such cases the survival and functional status of these patients can dramatically improve. Instead of most patients either dying or being transferred to nursing facilities, most patients survive and can live independently.

[0007] The tools currently developed and available to remove blood clots in the brain are still under development. An important aspect of treatment can be the use of constant suction pressure at a location proximal to the blood clot coupled with stent-like blood clot retrievers (“stent-trievers”) that physically trap the clots and allow removal. There is still considerable room for improvement in these devices. In addition, a meaningful percentage of patients who enter the oath lab for clot removal have no restoration of blood flow. More effective systems, devices and methods are necessary to treat these people.

[0008] One of the key challenges relates to the small blood vessels containing the blood clots. These blood vessels may have internal diameters of about 3mm or less. The vessels are often deep inside the brain and the path to reach them is tortuous. These realities create great challenges. But the reward for solving these problems is immense for those unfortunate enough to suffer a stroke.

[0009] Most strokes are treated with constant suction pressure proximal to the clot. The suction is provided by a catheter placed near or proximate the clot. If this is not sufficient, or if the interventionist prefers, a guidewire is passed adjacent to or through the clot and then distally beyond the clot. This guidewire is then used to guide the delivery of a stent-triever inside a small catheter. A stent-triever is deployed adjacent to the clot and is used to trap and physically remove the clot. The stent-triever may cause complications by breaking up the blood clot into pieces that travel distally or downstream into even smaller brain vessels. This causes obstruction of distal blood vessels and can cause more brain damage and disability for the patient. It would be useful to remove the blood clot while minimizing further risk of such additional harm to the patient.

[0010] Adding too much suction to a blood vessel may cause the vessel to collapse, making it even harder to remove the clot. Therefore, a physician using current systems, devices and methods based on constant suction fluid pressure must balance the need for using sufficient pressure to dislodge the blood clot with the competing need to avoid blood vessel collapse. Unfortunately, many cases can involve a blood clot that is securely attached to and/or lodged against the interior wall surface of the blood vessel making removal with current techniques very difficult or impossible. Aggressive use of current techniques in an effort to remove strongly adhered or lodged clots can result in complications harmful to the patient. [0011] Tools to remove blood clots in the brain are still under development. For example, the International Application published under the Patent Cooperation Treaty having International Application No. PCT/US2019/015220, International Publication No. WO 2019/147985, (the “’985 Publication”) discloses various improvements in this field, including devices for removing clots and related procedures, and is hereby fully incorporated by reference herein. For certain applications, further improvements are possible.

[0012] For these and other reasons, it would be desirable to provide systems, devices, and methods for more effectively treating stroke by removing blood clots during a catheter procedure.

Summary

[0013] In one general aspect, a method of removing a clot from a blood vessel is provided and includes advancing, together and without substantial relative motion therebetween, to a position in the blood vessel distal to the clot, an inner microcatheter and an outer microcatheter disposed about the inner microcatheter. The method further includes occluding the blood vessel distal to the clot by deploying a radially expandable distal seal disposed at a distal end portion of the inner microcatheter. The clot is moved in a proximal direction by directing, into the vessel distal to the clot and through the inner microcatheter, a fluid at a positive pressure sufficient to move the clot. The clot is captured and removed from the blood vessel.

[0014] The method may include various other optional features. For example, during the advancing the inner microcatheter and the outer microcatheter operation, the outer microcatheter covers at least part of the distal seal, and deploying the distal seal comprises moving the outer microcatheter proximally relative to the inner microcatheter to fully expose the distal seal. Moving the outer microcatheter proximally relative to the inner microcatheter to fully expose the distal seal may further comprise holding the inner microcatheter stationary and withdrawing the outer microcatheter proximally. Moving the outer microcatheter proximally relative to the inner microcatheter to fully expose the distal seal may further comprise holding the outer microcatheter stationary and advancing the inner microcatheter distally. Moving the outer microcatheter proximally relative to the inner microcatheter to fully expose the distal seal may further comprise moving both the inner microcatheter distally and the outer microcatheter proximally. During the advancing the inner microcatheter and the outer microcatheter operation, the outer microcatheter may cover substantially all of the distal seal, and deploying the distal seal may comprise moving the outer microcatheter proximally relative to the inner microcatheter to fully expose the distal seal. Before advancing the inner microcatheter and the outer microcatheter operation, the method may include advancing a guidewire from proximal to the clot to distal to the clot, and advancing the inner microcatheter and the outer microcatheter may comprise advancing the inner microcatheter and the outer microcatheter along the guidewire. Before advancing the guidewire, the method may further include positioning an elongate intravascular element in the blood vessel on a proximal side of the clot, and advancing the guidewire may include advancing the guidewire through the elongate intravascular element. Positioning the elongate intravascular element may comprise occluding the blood vessel proximal to the clot by expanding a radially expandable proximal seal extending from the elongate intravascular element. Positioning the elongate intravascular element may comprise advancing a delivery catheter into the blood vessel and advancing the elongate intravascular element through the delivery catheter. The method may further comprise applying suction in the blood vessel proximal to the clot.

[0015] In another general aspect, a system is provided for removing a blood clot from a blood vessel of a patient. The system may comprise a guidewire; an inner microcatheter disposed about the guidewire, the inner microcatheter comprising a radially expandable distal seal at a distal end portion thereof; an outer microcatheter disposed about the inner microcatheter; and an elongate intravascular element disposed about the outer microcatheter, the elongate intravascular element comprising a radially expandable proximal seal deployable from a distal end thereof.

[0016] The system may further comprise a delivery catheter disposed about the elongate intravascular element. During at least a portion of a clot removal procedure, the outer microcatheter may at least partially cover the distal seal.

[0017] In another general aspect, a system is provided for removing a blood clot from a blood vessel of a patient, comprising: an elongate intravascular element including a radially expandable proximal seal disposed at a distal end thereof; wherein the proximal seal has a longitudinal length that is substantially greater than an expanded diameter of the proximal seal.

[0018] In another general aspect, a system for removing a blood clot from a blood vessel of a patient includes an elongate intravascular element comprising a radially expandable proximal seal disposed at a distal end thereof; wherein a distal end portion of the proximal seal comprises a trumpet opening. [0019] In another general aspect, a system for removing a blood clot from a blood vessel of a patient includes: an elongate intravascular device comprising a distal seal disposed on a distal end portion thereof; wherein the distal seal is radially expandable to a diameter greater than the relaxed internal diameter of the blood vessel containing the blood clot to separate the clot from an interior wall surface of the blood vessel.

[0020] In another general aspect, a system for removing a blood clot from a blood vessel of a patient is provided and comprises: an elongate intravascular device comprising a distal seal disposed on a distal end portion thereof; wherein the distal seal comprises a generally flexible membrane supported by one or more longitudinally spaced-apart hoop frames.

[0021] In another general aspect, a system for removing a blood clot from a blood vessel of a patient comprises: an elongate intravascular device comprising a distal seal disposed on a distal end portion thereof; wherein the distal seal comprises a generally flexible membrane, a proximal portion of which is supported by a radially expanding stent.

[0022] In another general aspect, a system for removing a blood clot from a blood vessel of a patient comprises: an elongate intravascular device comprising a distal seal disposed on a distal end portion thereof; wherein the distal seal comprises a generally flexible membrane, substantially the entire length of which is supported by a radially expanding stent.

[0023] Various other aspects, advantages, features, or combinations of features and/or steps will be appreciated from the detailed description of the illustrative embodiments to follow, taken in conjunction with the accompanying drawings. Brief Description of the Drawings

[0024] Figure 1 is a schematic representation of a patient illustrating the use of an example clot removal system to remove a clot from a blood vessel in the patient’s brain.

[0025] Figures 1 A-1 E are longitudinal cross-sectional views schematically illustrating a clot removal system in accordance with one illustrative embodiment being used to dislodge and remove a blood clot.

[0026] Figures 2A and 2B are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0027] Figures 3A-3D are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0028] Figures 4A and 4B are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0029] Figures 5A-5D are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0030] Figures 6A-6D are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0031] Figures 7A and 7B are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot.

[0032] Figures 8A-8C are longitudinal cross-sectional views schematically illustrating another embodiment being used to dislodge and remove a blood clot. [0033] Figures 9A-9C are longitudinal cross-sectional views schematically illustrating other embodiments being used to dislodge and remove blood clots.

Detailed Description

[0034] The detailed description herein serves to describe non-limiting embodiments or examples involving various inventive concepts and uses reference numbers for ease of understanding these examples. Common reference numbers between the figures refer to common features and structure having the same or similar functions. While various figures will have common reference numbers referring to such common features and structure, for purposes of conciseness, later figure descriptions will not necessarily repeat a discussion of these features and structure. Generally, the features of the illustrative embodiments described herein may be used in connection with the various embodiments described in the ’985 Publication, in similar manners, and for similar purposes. Likewise, the features of the illustrative embodiments described in the ’985 Publication may be used in connection with the various embodiments described herein, in similar manners, and for similar purposes. Further, while certain features are described herein in connection with particular illustrative embodiments, it will be appreciated that any feature or features described herein may be utilized with any other embodiment, and in any combination.

Figures 1 and 1A-1E

[0035] Figure 1 is a schematic representation of a patient and portions of the vascular system of the patient, partially cross sectioned, and further illustrating a manner of using an example clot removal system 2 to remove a clot from a blood vessel in the patient’s brain. It will be appreciated that although exemplary embodiments are described herein in connection with removing clots from blood vessels in brains, some embodiments according to at least some aspects of the present disclosure may be used in procedures for removing obstructions from vessels in other body parts.

[0036] Figures 1A-1 E illustrate an obstruction or blood clot 10 in a blood vessel 12 having an interior wall surface 12a. The blood vessel 12 can comprise a proximal portion 11 and a distal portion 13, and can contain the blood clot 10 in the vessel between the portions 11, 13. The vessel 12 may be, for example, an artery in a patient’s brain.

[0037] Referring to Figure 1 A, an illustrative embodiment or example of a clot removal system 2 is shown and includes an elongate intravascular element, such as a suction catheter 14. The suction catheter 14 can comprise a distal end portion 15, which may be generally circular in cross section. The distal end portion 15 can comprise a mouth or proximal seal 16. The proximal seal 16 can be funnel-shaped and/or can be radially expandable. The proximal seal 16 may include a stent or stent like structure which can self-expand, such as upon being advanced distally from a delivery catheter 8.

[0038] During an operation to remove the blood clot 10, a user inserts the distal end 15 of the suction catheter 14 in its unexpanded form into the blood vessel 12 through the proximal portion 11. For example, the suction catheter 14 may be positioned near the clot 10 (e.g., proximal to the clot 10) by inserting it through the delivery catheter 8 extending to near the clot via the vascular system of the patient (see, e.g., Figure 1). The proximal seal 16 can be expanded radially to contact the interior wall surface 12a of the blood vessel 12 and create a seal against fluid flow near the proximal side of the blood clot 10. In the illustrated embodiment, proximal seal 16 includes an open distal end portion 16a, which may be configured to receive the clot 10 therethrough.

[0039] In some alternative embodiments, the proximal seal 16 may be disposed at the distal end of a proximal seal wire, which is advanced through the suction catheter 14. In some such embodiments, the proximal seal 16 may be deployed from the distal end portion 15 of the suction catheter 14 by relative motion of the proximal seal 16 in the distal direction. For example, the proximal seal 16 may be advanced distally through the stationary suction catheter 14, the suction catheter 14 may be withdrawn from the stationary proximal seal 16, or both the suction catheter 14 and the proximal seal 16 may be moved in opposite directions.

[0040] Referring to Figure 1 B, an elongate intravascular element, such as a guidewire 36, can be advanced through the length of the suction catheter 14, out of the proximal seal 16, and distally beyond the clot 10. Referring to Figure 1C, an elongate intravascular element, such as an outer microcatheter 26, and an elongate intravascular element, such as an inner microcatheter 27, may be advanced together over the guidewire 36 to a location distally beyond the clot 10. For example, the inner microcatheter 27 may be positioned within the outer microcatheter 26 before the microcatheters 26, 27 are inserted into the vascular system of the patient. The inner microcatheter 27 and the outer microcatheter 26 may be advanced together (e.g., simultaneously and/or without substantial relative motion between them) until they reach the location distally beyond the clot 10. [0041] Generally, the outer microcatheter 26 and the inner microcatheter 27 are disposed coaxially about the guidewire 36, with the inner microcatheter 27 disposed radially between the guidewire 36 and the outer microcatheter 26. Accordingly, the outer microcatheter 26 has a larger diameter than the inner microcatheter 27, and the inner microcatheter 27 has a larger diameter than the guidewire 36.

[0042] Referring to Figures 1C and 1 D, the inner microcatheter 27 can comprise a thin, radially expandable, and flexible distal seal 20 at its distal end portion 27a. The distal seal 20 may comprise a membrane constructed of polytetrafluoroethylene (PTFE), or other biocompatible, thin, strong, and flexible material. Prior to deployment of the distal seal 20, the outer microcatheter 26 at least partially covers the inner microcatheter 27, such as when the outer microcatheter 26 and the inner microcatheter 27 are advanced together over the guidewire 36 distally beyond the clot 10. In the illustrated embodiment, the outer microcatheter 26 covers substantially all of the inner microcatheter 27 that extends distally beyond the suction catheter 14, and the outer microcatheter 26 covers substantially the entire collapsed (unexpanded) distal seal 20 along the inner microcatheter 27. Covering substantially the entire collapsed distal seal 20 with the outer microcatheter 26 may prevent snagging, unraveling, or damage to the distal seal 20 as the outer microcatheter 26 and inner microcatheter 27 are advanced. An alternative embodiment in which the outer microcatheter 26 covers only a portion of the inner microcatheter 26 is shown in Figures 2A and 2B and is described below.

[0043] Referring again to Figures 1 C and 1 D, after the outer microcatheter 26 and the inner microcatheter 27 have been advanced together distally beyond the clot 10 along the guidewire 36, the distal seal 20 may be deployed. For example, the distal seal 20 may be exposed by moving the outer microcatheter 26 proximally relative to the inner microcatheter 27 and/or the moving the inner microcatheter 27 distally relative to the outer microcatheter 26. This may be accomplished by holding the inner micro catheter 27 stationary and withdrawing the outer micro catheter 26 proximally and/or by holding the outer micro catheter 26 stationary and advancing the inner micro catheter 27 distally, or by moving the microcatheters 26, 27 in opposite directions. After the distal seal 20 has been deployed, the outer micro catheter 26 may remain in a position generally proximal to the seal 20 as illustrated in Figure 1 D, or it may be further withdrawn.

[0044] The distal seal 20 may be radially expandable to seal against the interior wall surface 12a of the vessel 12 distal to the clot 10. Accordingly, the seal 20 may help protect against broken pieces of clot 10 or emboli traveling distally, such as into the brain of the patient. The proximal end of the seal 20 may be open. The seal 20 may be generally flexible, which may facilitate the seal 20 conforming to and sealing against the interior wall surface 12a of the vessel 12. The distal seal 20 may be constructed in various manners, such as those described elsewhere herein and in the ’985 Publication. For example, the distal seal 20 may be constructed with a supporting structure, such as the stent 20d shown in Figure 9C, arranged to radially expand the distal seal 20 self expanding manner when it is exposed.

[0045] The open proximal end of the distal seal 20 may be connected to the inner micro catheter 27 by one or more tethers 25, which may aid in maintaining the distal seal 20 in the desired configuration and/or which may prevent inversion of the distal seal 20 if the inner microcatheter 27 is pulled proximally. The tethers 25 may be integrally formed with the seal 20, or may be separate and then suitably attached to the seal 20 and the inner micro catheter 27.

[0046] Referring to Figure 1 D, once the distal seal 20 has been deployed, the clot 10 is substantially contained within a sealed volume of the vessel 12 between the distal seal 20 on the distal side of the clot 10 and the proximal seal 16 on the proximal side of the clot.

[0047] A pressure source/control 22 may provide and/or control suction and/or positive fluid pressure to various components of the system 2. For example, the inner micro catheter 27 may comprise one or more holes or perforations 23 of any desired number, shape, and/or configuration for infusing a fluid. The perforation(s) 23 may be located proximal to the attachment point of the distal seal 20 to the inner microcatheter 27 so that they are generally within the distal seal 20. The perforations 23 may allow fluid communication between an interior of the inner microcatheter 27 and the environment surrounding the inner microcatheter 27, such as within the distal seal 20 and/or within the vessel 12 distal to the clot 10. The pressure source/control 22 may be operatively coupled to supply positive pressure via the inner microcatheter 27 and the perforations 23. Specifically, the pressure source/control 22 and the inner microcatheter 27 may deliver a pressurized fluid (e.g., a liquid, a gas, or a combination of liquid and gas), such as carbon dioxide (CO2) 19 via the perforation(s) 23. Other fluids that may be supplied by the pressure source/control 22 via the perforation(s) 23 include any biocompatible liquids and/or biocompatible gasses (e.g., air, oxygen, or anesthetic gasses). Fluids may include medications, which may aid in dilating the vessel 12 and/or dissolving the clot, and/or may protect the brain, for example. [0048] Applying positive pressure within the distal seal 20 via the perforations 23 may aid in expanding the distal seal 20 and/or in creating a sealed engagement of the distal seal 20 against the interior wall surface 12a of the vessel 12. Referring to Figure 1 E, applying positive pressure within the vessel 12 distal to the clot 10 may aid in freeing the clot 10 from its lodged location against the interior wall surface 12a of the vessel 12 and/or may push the clot 10 in a proximal direction to the open distal end portion 16a of the suction catheter 14. Generally, the positive pressure at which the fluid (e.g., CO2 19) is directed into the vessel 12 distal to the clot 10 may be sufficient to move the clot 10 in the proximal direction.

[0049] In some embodiments, the pressure source/control 22 may apply suction pressure, such as via the suction catheter 14. For example, suction may be applied via the suction catheter 14 when the guidewire 36 is being advanced past the clot 10 and/or when positive pressure is being applied via the perforations 23. The pressure delivered through the perforation(s) 23 and/or the suction applied via the suction catheter 14 may be continuous (constant) or pulsed (cycled) at one or more desired frequencies and amplitudes of pressure, such as controlled by the pressure source/control 22. Some example embodiments may utilize suction only, positive pressure only, or both suction and positive pressure.

[0050] In some embodiments, the pressure source/control 22 may comprise an electronically controlled pump, which may be configured with various control algorithms. For example, the pressure source/control 22 may be configured to avoid suction of blood beyond a predetermined amount. The pressure source/control 22 may be configured to recognize when a clot 10 has been captured in the proximal seal 16. The pressure source/control 22 may be configured to limit positive pressure and/or suction within predetermined limits. The pressure source/control 22 may be configured to minimize the introduction of air into the clot removal system 2.

[0051] Although the pressure source/control 22 is not specifically described in connection with each embodiment described herein, it will be appreciated that any embodiment described herein may include components for providing positive and/or negative pressure and one or more controls associated therewith, such as pressure source/control 22.

Figures 2A and 2B

[0052] Figures 2A and 2B show an alternative illustrative embodiment or example of a clot removal system 2a. Clot removal system 2a is generally similar to clot removal system 2, includes similar components, and is used in a similar manner; however, in clot removal system 2a the outer microcatheter 27 covers only a portion of the inner microcatheter 26, such as when the outer microcatheter 26 and the inner microcatheter 27 are advanced together over the guidewire 36 distally beyond the clot 10.

Specifically, referring to Figure 2A, the outer microcatheter 27 at least partially covers the tethers 25 but does not cover the unexpanded distal seal 20 while the outer microcatheter 26 and the inner microcatheter 27 are initially advanced together over the guidewire 36 distally beyond the clot 10.

[0053] In this embodiment, the delivery catheter 8, the suction catheter 14, the proximal seal 16, and the guidewire 36 are utilized in a manner similar to that describe above with respect to clot removal system 2. The outer microcatheter 26 and the inner microcatheter 27 are advanced together over the guidewire 36 with the unexpanded distal seal 20 at least partially exposed. Then, referring to Figure 2B, the outer microcatheter 26 may be moved distally with respect to the inner microcatheter 27 to expose the tethers 25. The distal seal 20 is expanded and the clot 10 is removed in a manner similar to that described above with respect to clot removal system 2.

Figures 3A-3D

[0054] Figures 3A-3D show an alternative illustrative embodiment or example of a clot removal system 2b. Clot removal system 2b is generally similar to clot removal system 2, includes similar components, and is used in a similar manner; however, clot removal system 2b may not include components positioned distal to the clot 10.

Instead, clot removal system 2b utilizes suction applied by the suction catheter 14 to draw the clot 10 into the proximal seal 16.

[0055] Referring to Figure 3A, the clot 10 is approached by the suction catheter 14, which may extend through the delivery catheter 8. The open distal end portion 16a of the proximal seal 16 is positioned proximal to the clot 10, and the proximal seal 16 is expanded. For example, suction catheter 14 may be held stationary while the delivery catheter 8 is withdrawn, allowing the proximal seal 16 to expand radially.

[0056] The proximal seal 16 has a longitudinal length between the distal end portion 15 of the suction catheter 14 and the open distal end portion 16a of the proximal seal 16 that is greater than the interior diameter of the vessel 12. In some embodiments, the length of the proximal seal 16 may be several times the diameter of the vessel 12. The proximal seal 16 is constructed from a flexible membrane supported by a self-expanding stent-like structure or stent. The proximal seal 16 may be in its radially contracted configured when it is within the deliver catheter 8, and proximal seal 16 may self-expand as it is advanced distally out of the delivery catheter 8. The elongated portion of the proximal seal 16 may be generally cylindrical, and the proximal portion may taper generally in a funnel shape to about the interior diameter of the delivery catheter 8.

[0057] Referring to Figures 3B and 3C, suction may be applied via the suction catheter 14 using the pressure source/control 22, which may draw the clot 10 into the proximal seal 16. Because the proximal seal 16 in this embodiment is longer than the clot 10, the clot 10 may be drawn fully within the proximal seal 16.

[0058] Referring to Figure 3D, once the clot 10 has been drawn into the proximal seal 16, the delivery catheter 8 and the suction catheter 14 may be withdrawn proximally, carrying the clot 10 with them. Because the proximal seal 16 is longer than the clot 10 and the clot is fully within the proximal seal, the risk of inadvertently leaving pieces of the clot in the vessel 12 as the catheters 8, 14 are withdrawn may be reduced. [0059] It will be appreciated that detailed features of the proximal seal 16 described in connection with this illustrative embodiment may be used in connection with other embodiments, such as the clot removal system 2 described above.

Figures 4A and 4B

[0060] Figures 4A and 4B show an alternative illustrative embodiment or example of a clot removal system 2c. Clot removal system 2c is generally similar to clot removal system 2b, includes similar components, and is used in a similar manner; however, clot removal system 2c includes a proximal seal 16b having a radially outwardly extending distal opening (“trumpet opening”) 16c. [0061] The proximal seal 16b may be elongated, generally cylindrical, self expanding, and may be constructed similar to the proximal seal 16 described above. The trumpet opening 16c may be a short portion at the distal end that has a larger diameter than the elongated main portion of the proximal seal 16b.

[0062] Generally, clot removal system 2c may be utilized in a manner similar to clot removal system 2b. In some circumstances, the trumpet opening 16c of proximal seal 16b may facilitate a more effective sealing engagement between the proximal seal 16b and the interior wall surface 12a of the vessel 12 because the distal-most edge presses radially outward into the vessel 12. In some circumstances, the trumpet opening 16c may facilitate easier and/or more complete capture of the clot 10 because the outwardly extending trumpet opening 16c may serve to funnel the clot 10 into the main portion of the proximal seal 16b. It will be appreciated that a trumpet opening 16c may be utilized in connection with other embodiments, such as embodiments including components positioned distal to the clot 10.

Figures 5A-5D

[0063] Figures 5A-5D show an alternative illustrative embodiment or example of a clot removal system 2d. Clot removal system 2d is generally similar to clot removal system 2, includes similar components, and is used in a similar manner; however, clot removal system 2d may not include one or both of the microcatheters 26, 27. Instead, referring to Figure 5A, clot removal system 2d may include an elongate intravascular element, such as a guidewire 18, extended through a suction catheter 14, which may extend through a delivery catheter 8. [0064] Referring to Figure 5B, the guidewire 18 may include the distal seal 20 at its distal end portion 18a. After the guidewire 18 is advanced distal to the clot 10, the distal seal 20 may be radially expanded. Referring to Figure 5C, positive pressure via the perforations 23 and/or suction via the suction catheter 14 may be used to move the clot 10 into the proximal seal 16.

[0065] Referring to Figure 5D, the guidewire 18 may be withdrawn proximally to pull the proximal portion of the distal seal 20 into the proximal seal 16 of the suction catheter 14, which may capture the clot 10 therein for removal from the vessel 12. Figures 6A-6D

[0066] Figures 6A-6D show an alternative illustrative embodiment or example of a clot removal system 2e. Clot removal system 2e is generally similar to clot removal system 2, includes similar components, and is used in a similar manner; however, clot removal system 2e may not include the outer microcatheter 26.

[0067] Referring to Figure 6A, after the suction catheter 14 and its proximal seal 16 are deployed via the delivery catheter 8, the guidewire 36 is advanced distally past the clot 10. The microcatheter 27 comprising the distal seal 20 is advanced over the guidewire to position the distal seal 20 distal to the clot 10, then the distal seal 20 is expanded (Figure 6B).

[0068] Referring to Figure 6C, positive pressure via the perforations 23 and/or suction via the suction catheter 14 may be used to move the clot 10 into the proximal seal 16.

[0069] Referring to Figure 6D, the microcatheter 27 and/or the guidewire 36 may be withdrawn proximally to pull the proximal portion of the distal seal 20 into the proximal seal 16 of the suction catheter 14, which may capture the clot 10 therein for removal from the vessel 12.

Figures 7 A and 7B

[0070] Figures 7A and 7B show an alternative illustrative embodiment or example of a clot removal system 2f. Clot removal system 2f is generally similar to clot removal system 2, includes similar components, and is used in a similar manner; however, clot removal system 2f may comprise an elongate intravascular element, such as a guidewire 36a, with an attached distal seal 20 coupled to an elongate intravascular element , such as a microcatheter 27a, by tethers 25.

[0071] Referring to Figure 7A, after the suction catheter 14 and its proximal seal 16 are deployed via the delivery catheter 8, the guidewire 36a and the microcatheter 27a (with the distal seal 20 in an unexpanded state) may be advanced together to position the distal seal 20 distal to the clot 10. Then, the distal seal 20 may be expanded, such as by the infusion of fluid via the open distal tip 27b of the microcatheter 27a. In some embodiments, the microcatheter 27a may include holes or perforations similar to perforations 23 in place of or in addition to its open distal tip 27b. [0072] Referring to Figure 7B, positive pressure via the microcatheter 27a and/or suction via the suction catheter 14 may be used to move the clot 10 into the proximal seal 16. The microcatheter 27a and/or the guidewire 36a may be withdrawn together proximally to pull the proximal portion of the distal seal 20 into the proximal seal 16 of the suction catheter 14, which may capture the clot 10 therein for removal from the vessel 12. Figures 8A-8C

[0073] Figures 8A-8C show an alternative illustrative embodiment or example of a clot removal system 2g. Clot removal system 2g is generally similar to clot removal system 2d of Figures 5A-5D, includes similar components, and is used in a similar manner; however, clot removal system 2g may comprise a distal seal 20a configured to expand to a diameter substantially greater than the relaxed internal diameter of the vessel. In some circumstances, it may be beneficial to radially expand the vessel 12 to aid in separating the clot 10 from the interior wall surface 12a. Clot 10 inside a vessel 12 tends to become adherent to the vessel wall surface 12a. By radially expanding the vessel 12, at least part or even all of the clot 10 can be separated from the interior wall surface 12a.

[0074] Referring to Figure 8A, the clot removal system 2g may include a guidewire 18 extended through a suction catheter 14 having a proximal seal 16, which may extend through a delivery catheter 8. The guidewire 18 may include the distal seal 20a at its distal end portion 18a.

[0075] Referring to Figure 8B, after the guidewire 18 is advanced distal to the clot 10, the distal seal 20a may be radially expanded. Positive pressure via the perforations 23 may expand the distal seal 20a and the adjacent portion of the vessel 12 radially outward. Because the distal seal 20a is configured to expand to a diameter greater than the relaxed internal diameter of the vessel 12, the expanded distal seal 20a may push the interior wall surface 12a of the vessel 12 away from the radially outward surfaces of the clot 10. Accordingly, the clot 10 may be released from the interior wall surface 12a of the vessel 12. [0076] Referring to Figure 8C, the distal seal 20a may be partially deflated, allowing the vessel 12 to return to approximately its relaxed diameter. The guidewire 18 may be withdrawn proximally to pull the proximal portion of the distal seal 20a into the proximal seal 16 of the suction catheter 14, which may capture the clot 10 therein for removal from the vessel 12.

[0077] It will be appreciated that any embodiment may include a distal seal that is capable of being radially expand to a diameter greater than the relaxed inner diameter of the vessel 12. This allows the distal seal to expand sufficiently to properly engage the interior wall surface 12a of the vessel 12 to create the fluid-tight interface for different sizes of vessels 12. Whether the distal seal is radially expanded substantially beyond the relaxed internal diameter of the vessel 12 as illustrated in Figure 8B and the extent of such expansion may be controlled during the procedure, such as by controlling the level of positive pressure of fluid supplied via the perforations 23.

Figures 9A-9C

[0078] Figures 9A-9C illustrate example clot removal systems 2h, 2i, 2j, which include optional, alternative distal seal 20 supporting structures. Clot removal systems 2h, 2i, 2j are generally similar to clot removal system 2d of Figures 5A-5D, include similar components, and are used in similar manners; however, the distal seals 20 in clot removal systems 2h, 2i, 2j comprise optional, alternative supporting structures. Generally, these alternative distal seal 20 supporting structures may be used with distal seals 20 disposed on any elongate intravascular devices, including any clot removal systems described herein. [0079] Referring to Figure 9A, the distal seal 20, which may comprise a generally flexible membrane, is supported by one or more longitudinally spaced-apart hoop frames 20b. In some embodiments, the hoop frames 20b may be generally circular or generally elliptical in shape. The hoop frames 20b may be initially configured in a collapsed configuration to allow the guidewire 18 and distal seal 20 to advance distally past the clot 10. After the distal seal 20 is positioned distal to the clot 10, the hoop frames 20b may be allowed transition to the expanded configuration shown in Figure 9A, such as by unfolding in a self-expanding manner.

[0080] Referring to Figure 9B, the proximal portion of the distal seal 20, which may comprise a generally flexible membrane, is supported by a stent-like structure or stent 20c, which may be arranged to radially expand less than the entire longitudinal length of the distal seal 20. In some embodiments, the proximal opening may be supported by a hoop frame 20b, which may be generally circular or generally elliptical. [0081] Referring to Figure 9C, the distal seal 20, which may comprise a generally flexible membrane, may be supported by a stent-like structure or stent 20d, which may be arranged to radially expand substantially the entire longitudinal length of the distal seal 20. In some embodiments, the proximal opening may be supported by a hoop frame 20b, which may be generally circular or generally elliptical.

[0082] The hoop frames 20b, stent 20c, and/or stent 20d may be constructed from any suitable materials, such as shape memory alloys (e.g., Nitinol).

[0083] As used herein, the term “blood clot” means any obstruction or clot material impeding the flow of blood in a blood vessel, regardless of the material forming the obstruction or the origin of the material. As used herein, “elongate intravascular element” means a wire, guidewire, catheter or microcatheter, or other similar device configured for insertion into and use within the vascular system of a patient. As used herein, “catheter” and “microcatheter” mean an elongate intravascular element having a longitudinal lumen extending therethrough, which may be used to convey fluid and/or other elongate intravascular elements, regardless of diameter. As used herein, “positive pressure” refers to a pressure that is greater than the pressure at the relevant location. As used herein, “suction” refers to a pressure that is less than the pressure at the relevant location. Accordingly, “positive pressure” and “suction” are relative terms that should be considered in the context of the pressure at the relevant location immediately before the “positive pressure” or “suction” is applied. As used herein, “suction catheter” refers to a catheter such as one having the structure and features as described herein, regardless of whether it is specifically configured to apply suction and regardless of whether it is used to apply suction in a particular procedure.

[0084] While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative product and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept. For example, any of the individual features or aspects described herein may be utilized alone or together in any combination depending on the desired results and attendant advantages.