WO2011011493A1

WO2011011493A1 - System and method for removing a blood clot

Info

Publication number: WO2011011493A1
Application number: PCT/US2010/042716
Authority: WO
Inventors: Yi Yang; Scott L. Jahrmarkt
Original assignee: Neurointerventional Therapeutics, Inc.
Priority date: 2009-07-23
Filing date: 2010-07-21
Publication date: 2011-01-27

Abstract

A system and method for removing a blood clot in a blood vessel includes the use of a catheter, an elongate member extending through the catheter, and a tube coupled to the distal end of the elongate member to infuse fluid to the blood clot and to apply suction to the blood clot for removal of fluid therefrom. The method includes distally advancing a guidewire through the blood vessel, distally advancing a microcatheter over the guidewire, removing the guidewire, distally advancing the elongate member through the microcatheter, removing the microcatheter, distally advancing the suction catheter over the elongate member, and aligning the suction catheter and tube relative to each other and to the blood clot in a fluid infusion configuration and/or in an aspiration configuration for, respectively, fluid infusion and aspiration.

Description

SYSTEM AND METHOD FOR REMOVING A BLOOD CLOT

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001 ] This invention relates broadly to systems and methods for removing blood clots in patients. More particularly, this invention relates to systems and methods for removing a blood clot in the brain of a patient.

2. State of the Art

[0002] A stroke is caused by a rupture or an occlusion of a blood vessel which leads to oxygen deprivation in the brain. In the United States, nearly eight-hundred thousand people suffer a stroke each year, and over one-hundred and forty thousand people die from strokes each year. Stroke is the leading cause of serious, long-term disability in the United States and the third leading cause of death. Approximately three quarters of strokes in the United States are first attacks and approximately one quarter are recurrent attacks. Eighty percent are ischemic in nature, meaning that they are caused by a restriction, obstruction, or blockage in the blood supply of the patient, and twenty percent are hemorrhagic, meaning that they are caused by excessive bleeding. The economic cost of stroke to the United States is over forty billion dollars per year. The direct costs of medical care and therapy are almost thirty billion dollars per year.

[0003] It is well known in the art that the extent to which treatment of a stroke is successful in preventing death and/or in reducing the consequent damage to a patient is largely influenced by the time which elapses between the onset of the stroke and the proper treatment of the stroke. The elapsed time is a function of not only whether or not a patient is able to get to a medical facility or hospital, but also the nature of the stroke and whether or not the particular medical facility or hospital to which the patient is initially brought is best equipped to treat the stroke. The capability of the medical facility to treat the particular stroke may not be known until the patient is properly evaluated and analyzed. Generally, if more than three hours elapse between the onset of the stroke and treatment, then a combination of tPA (Tissue Plasminogen Activator - a drug used to dissolve blood clots) and mechanical treatments need to be utilized. [0004] If a cerebral clot is diagnosed and removed within four hours of the clot's formation, a patient generally has a better chance to recover fully. If a neurointerventionist happens to be present (most are generally located at stroke centers), then certain devices may be available to remove the cerebral clot. One device is the Merci retrieval device made by Concentric

Medical. With the Merci device, a small catheter (e.g., having a 0.015" inner diameter) is advanced through the femoral artery and fed up to the brain. A special nitinol wire is advanced through the catheter to the clot. The wire changes form after passing through the clot and can be used to pull out the clot. A second device, sold by Penumbra, Inc. also uses a small catheter which is advanced through the femoral artery and fed up to the brain, but instead of pulling the clot out mechanically, utilizes suction to pull out the clot. Both of these devices are often unsuccessful in their intended functions.

SUMMARY OF THE INVENTION

[0005] The invention provides a system and method for removing a blood clot from the brain of a patient. The system includes a relatively short catheter which is to be inserted in the carotid artery (it is too short to reach the brain from the femoral artery). The catheter includes a proximal section, a distal section, and a channel between the proximal and distal sections. The system also includes an elongate member (e.g., a wire) extending through the channel of the catheter and movable relative thereto, and a tube coupled to a distal end of the elongate member. The tube has proximal and distal openings. The system is configurable to a fluid infusion configuration and to an aspiration configuration. In the fluid infusion configuration, a proximal opening in the tube is disposed inside the channel of the catheter, and a distal opening of the tube is disposed inside or adjacent the blood clot outside of the catheter. In the fluid infusion configuration, a fluid, preferably a Tissue Plasminogen Activator (tPA) is infused through the channel of the catheter (around the elongate member) and into the blood clot for dissolving and breaking up the blood clot. To reach the aspiration configuration, the elongate wire and tube are advanced distally relative to the catheter. In the aspiration configuration, the tube is disposed distal of the catheter and suction is applied to the channel of the catheter in order to pull fluid proximally from the blood clot into and through the catheter. During proximal movement of the blood clot through the catheter, the elongate member may be manually translated proximally and distally relative to the catheter in order to agitate the blood clot and prevent blockage of fluid at the catheter's distal opening as well as in the catheter itself.

[0006] The fluid infusion configuration of the system is achieved by puncturing the carotid artery, distally advancing a guidewire through the carotid artery toward the blood clot, distally advancing a microcatheter over the guidewire toward the blood clot, withdrawing the guidewire from the carotid artery, distally advancing the elongate member with its distally located tube through the microcatheter toward the blood clot, withdrawing the microcatheter from the carotid artery, and distally advancing a suction catheter over the elongate member and a portion of the tube to a position adjacent the blood clot. The aspiration configuration of the system may be achieved from the fluid infusion configuration by simply distally translating the elongate member and tube relative to the blood clot and the suction catheter.

[0007] In one embodiment, the proximal section of the suction catheter defines a port in fluid communication with the channel of the catheter. The port is utilized both for infusing fluid in the fluid infusion configuration and for applying suction to the channel of the catheter in the aspiration configuration. The distal section of the suction catheter tapers down at its distal outlet.

[0008] In one embodiment, the distal outlet of the catheter is cut at an angle to increase the surface area of the outlet opening.

[0009] In one embodiment, the elongate member has an outer diameter similar to the inner diameter of the outlet of the catheter, and further includes a neck portion near its distal end which has a substantially smaller diameter than that of the distal outlet of the catheter. During fluid infusion, the neck portion is disposed proximal of the catheter outlet. During aspiration, the neck portion extends from a first location proximal of the catheter outlet to a second location distal of the catheter outlet. In this manner, when the elongate member is manually translated proximally and distally relative to the catheter during aspiration, the neck portion, being of reduced diameter, can agitate the clot at the distal outlet of the catheter so that portions of the blood clot (or the entire blood clot itself) can be proximally translated into the channel of the catheter. [0010] In one embodiment, the tube includes a plurality of distal openings axially offset from each other so that fluid is infused at multiple axial locations around the blood clot.

[0011 ] Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a cross-sectional view of the system of the invention in a fluid infusion configuration.

[0013] FIG. 2 is a cross-sectional view of the system of the invention in an aspiration configuration.

[0014] FIG. 3 is a cross-sectional view of another embodiment of the proximal section of the suction catheter of the system of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Turning to FIGS. 1 and 2, the system 10 of the invention includes a suction catheter

12, an elongate member 14, and a tube 16. The system 10 is configurable to a fluid infusion configuration (FIG. 1) and an aspiration configuration (FIG. 2) in an artery 11 in the brain of a patient for delivering a clot dissolving fluid to a blood clot 13 and for aspirating the blood clot

13. The setup and operation of the system 10 is further discussed below following a description of the catheter 12, elongate member 14, and tube 16.

[0016] As shown in FIG. 1, the suction catheter 12 includes a proximal section 12a and a distal section 12b which together define a channel 18. The catheter 12 is less than 50 cm long, and preferably is approximately 35 cm long. Along most of its length, the catheter 12 has an inner diameter 21 of at least approximately 0.022 inches and an outer diameter 23 of no larger than approximately 0.040 inches. The proximal section 12a of the suction catheter 12 preferably includes a port 20 in fluid communication with the channel 18 of the catheter 12 for infusing fluid to the channel 18 and for applying suction to the channel 18 as further discussed below. The port 20 is connectable to a source of suction (negative pressure) (not shown) and to a source of fluid (not shown), and may also attach to or be equipped with a valve (not shown) for regulating pressure and fluid flow therethrough. The proximal section 12a of the catheter 12 also includes a proximal end 22, and a seal 24 disposed at the proximal end 22. The seal 24 maintains the pressure inside the channel 18 of the catheter 12 while allowing proximal and distal longitudinal (axial) translation of the elongate member 14 through the seal 24 as further discussed below. The seal 24 thus preferably includes an aperture which is just large enough to receive the elongate member 14, and which may be stretchable in size to allow insertion of the elongate member 14 therethrough (e.g., the seal 24 preferably forms a compression seal around the elongate member 14 to prevents any air or fluid from escaping from the channel 18 without providing too much resistance to axial translation of the elongate member 14). A Y-shaped Touhy Borst hemostasis valve may be used to implement both the port 20 and the seal 24.

[0017] The distal section 12b of the suction catheter 12 preferably includes a necked down outlet portion 26 including a tapered portion 28 and a reduced diameter distal portion 30. The tapered portion 28 is in fluid communication with the channel 18 and reduces the inner diameter of the channel 18 to that of the distal outlet portion 30. The distal outlet portion 30 has an inner diameter 31 (FIG. 2) of approximately 0.015 inches, an outer diameter 33 (FIG. 2) of approximately 0.020 inches, extends along a length of approximately 1-5 millimeters, and ends in a diagonally cut distal end 34. The distal outlet portion 30 is in fluid communication with the tapered portion 28 and with the intracranial artery 11.

[0018] The elongate member 14 is preferably a wire which extends through the channel 18 of the catheter 12, is longer than the catheter 12, and has an outer diameter 35 of no larger than approximately 0.014 inches. The elongate member 14 has a proximal end 14a, a distal end 14b, and preferably includes a neck portion 36 near the distal end 14b of the elongate member 14. The neck portion 36 has a diameter 39 which is substantially smaller than the inner diameter 31 of the distal outlet 30 of the nozzle 26 of the catheter 12, and is preferably approximately 0.005 inches. At the ends 36a, 36b of the neck portion 36, the diameter of the elongate member 14 tapers to the outer diameter 35 of the remainder of the elongate member 14 (no larger than 0.014 inches). [0019] The tube 16 is coupled to the distal end 14b of the elongate member 14, and preferably slides over the distal end 14b. The tube 16 is preferably a hypotube and includes an outer wall 44 (FIG. 2) which defines a proximal portion 16a, a distal portion 16b, and a fluid path 46 between the proximal and distal portions 16a, 16b. The tube 16 also preferably includes proximal and distal ends 47, 49 which define the ends of the fluid path 46. It will be appreciated that the proximal end 47 (FIG. 2) of the tube 16 slidably couples over the distal end 14b of the elongate member 14 and preferably forms a seal therewith. Thus, it is preferred that the outer wall 44 of the tube 16 have a diameter marginally larger than the outer diameter 35 of the distal end 14b of the elongate member 14. The tube 16 may be glued, welded, or otherwise fixed in place. The tube 16 may alternatively be constructed to be integrally formed with the elongate member 14. It will also be appreciated that a stop (not shown) may be provided near the proximal end of the tube 16 which extends across the cross section of the tube 16 and the distal end 14b of the wire 14 can be connected to the stop.

[0020] The proximal portion 16a of the tube 16 includes at least one proximal opening 48 adjacent the proximal end 47, and the distal portion 16b of the tube 16 includes at least one distal opening 50 adjacent the distal end 49. The proximal and distal openings 48, 50 are preferably circular or oval shaped, and are fluidly coupled to the fluid path 46. The proximal opening 48 is preferably larger than each of the distal openings 50, and the proximal and distal openings 48, 50 are all preferably axially (longitudinally) offset from each other. Thus, the fluid path 46 extends from the at least one proximal opening 48 to the at least one distal opening 50 along a substantial length of the tube 16. As shown, four distal openings 50 and one proximal opening 48 may be provided. The number of proximal and distal openings 48, 50 may be varied as desired. In addition, circumferentially offset proximal and/or distal openings may be provided.

[0021 ] A flexible distal wire 52 is preferably attached to the distal end 49 of the tube 16. The distal wire 52 has a rounded atraumatic tip 54 at its distal end. An atraumatic coil 56 surrounds the distal wire 52 and has approximately the same outer diameter as the outer diameter of the tube 16 and elongate member 14. It will be appreciated by those skilled in the art that the flexible distal wire 52, rounded tip 54, and atraumatic coil 56 will help to soften the impact forces/pressure applied to the intracranial vasculature as the system 10 is advanced therethrough as further discussed below.

[0022] Turning now to the setup and operation of the system 10, the following method allows a surgeon to achieve the fluid infusion configuration of FIG. 1. First, the carotid artery 11 is punctured (preferably near where the proximal end 22 of the suction catheter 12 will be positioned). A guiding catheter (typically 5 French) or a sheath (typically 6 French) is inserted into the carotid artery 11. A guidewire (typically 0.014 inch) is then distally advanced through the carotid artery 11 up the intracranial vasculature to cross the blood clot 13. A microcatheter is then distally advanced over the guidewire to a position distal of the blood clot 13. Typically, this is all accomplished using fluoroscopy. The guidewire is then withdrawn, leaving the microcatheter in position. The elongate member 14 tube 16, and distal wire 52 (collectively, the "perfusion wire") are advanced through the microcatheter to the blood clot 13. The microcatheter is then withdrawn, leaving the perfusion wire in place. The suction catheter 12 is then distally advanced over the elongate wire 14 and tube 16. With this method, the "wire position" is maintained at the blood clot.

[0023] The elongate member 14 with the tube 16 is then properly aligned to ensure that the distal openings 50 of the tube 16 are aligned in or adjacent the blood clot 13 as shown in FIG 1. The catheter 12 is also properly aligned relative to the tube 16 such that the at least one proximal hole 48 of the tube 16 is located at the proximal tapered section 28 of the catheter 12, and the at least one distal hole 50 of the tube 16 is located distal of the distal end 34 of the catheter 12. The elongate member 14 and the catheter 12 preferably include respective markers 58, 60 to assist with alignment of the catheter 12 and tube 16 relative to each other. The catheter 12 may also be made from transparent material to facilitate visibility of the markers 58 on the elongate member 14 disposed within the channel 18 of the catheter 12 outside of the body. It will be appreciated that as the specific anatomy of a person (height, artery length, etc), the location of a given blood clot 13, and the location at which the carotid artery 11 is accessed will vary from person to person and from situation to situation, at least one of the elongate member 14 and the catheter 12 may contain a plurality of the markers 58, 60 along a substantial portion of its length to assist with alignment of the catheter 12 and tube 16. The markers 58, 60 may include colors, numbers, letters, etc. Additional cameras/scopes or other visual aids may also be utilized to ensure proper alignment of the distal openings 50 at or adjacent the clot 13 and/or proper alignment of the catheter 12 relative to the tube 16.

[0024] Once the system 10 is aligned in the fluid infusion configuration of FIG. 1, a fluid such as Tissue Plasminogen Activator (tPA) may be injected through the port 20 with a fluid source (not shown) under pressure. It will be appreciated that the tPA will move distally under pressure through the channel 18 of the catheter 12 to the tapered section 28 of the catheter 12. It will also be appreciated that as the inner diameter 31 of the distal outlet 30 is less than 1/lOOOth of an inch larger than the outer diameter of the tube 16 (which is marginally larger than the outer diameter 35 of the elongate member 14), the tPA will be mostly forced into the proximal opening 48 of the tube 16 disposed within the tapered section 28 of the nozzle 26. A trickle of tPA may exit the distal end 34 of the outlet 30, which extends over the hypotube 16. It is noted that the fit between the distal outlet 30 and the hypotube 16 is preferably tight enough to mostly prevent the tPA from escaping between the tube 16 and the distal outlet 30, but not so tight as to preclude manual axial translation of the elongate member 14. It is believed that the tapered section 28 creates a pressure drop which increases the velocity of the fluid as it enters the tube 16.

[0025] Upon entering the proximal opening 48, the fluid is guided by the fluid path 46 to the distal openings 50 and ejected therefrom into the blood clot 13 in the carotid artery 11. It will be appreciated that the velocity of the fluid exiting the distal openings 50 will be a function of the number of distal openings 50, the size of the respective proximal and distal openings 48, 50, and the pressure of the fluid as it enters the tube 16. In addition, as the openings 48, 50 are each axially offset relative to each other along the length of the tube 16, the infusion fluid is administered at and adjacent the blood clot 13. It is noted that during fluid infusion, the neck portion 36 of the elongate member 14 is disposed proximal of the outlet portion 26 of the catheter 12.

[0026] After infusion is completed, the fluid source may be removed from the port 20 and the system 10 may be reconfigured to the aspiration configuration of FIG. 2. This is accomplished by simply distally translating the elongate member 14 and tube 16 relative to the blood clot 13 (which is now presumably at least partially dissolved or broken up) and the suction catheter 12 such that the neck portion 36 of the elongate member 14 extends through the outlet portion 26 of the catheter 12, and preferably through the blood clot 13 as well.

Again, the markers 58, 60 may be coded along the length of the catheter 12, elongate member 14, or both to facilitate proper alignment thereof. At this point, the proximal and distal ends 47, 49 of the tube 16 are disposed distal of the catheter 12 as shown in FIG. 2.

[0027] A suction device (not shown) is operably coupled to the port 20 and suction is applied to the channel 18 of the catheter 12 through the port 20. It will be appreciated that the seal 24 at the proximal end 22 of the elongate member 14 prevents ambient air from entering the channel 18. Thus the suction force is transmitted through the channel 18 and applied at the distal outlet 30 of the catheter 12, causing fluid/material from the clot 13 to move proximally into the distal outlet 30.

[0028] During aspiration of the fluid/material from the clot 13, the elongate member 14 may be grasped at the proximal end 14a and manually translated axially in the proximal and distal direction. As discussed above, the seal 24 maintains the fluid-tight integrity of the channel 18 while allowing axial translation of the elongate member 14. It will be appreciated that proximal and distal translation of the elongate member 14 during aspiration will axially translate the neck portion 36 through the clot 13, which will cause agitation thereof and help to further loosen/break up the clot 13, as well as any material in and distal to the outlet 30. It will also be appreciated that due to the reduced diameter of the neck portion 36, blockage of the distal outlet 30 by the elongate member 14 is minimized. Axial movement of the neck portion 16 through the distal outlet 30 during suction/aspiration also helps to ensure that fluid/material from the clot 13 does not clog the distal outlet 30. The diagonal cut distal end 34 of the distal outlet 30 provides a larger surface area for entry of fluid/material from the clot 13 (e.g., gives the outlet 30 a diagonal cross section, which is larger than an orthogonal cross section). Once the blood clot 13 has been aspirated to the proximal section 12a of the catheter 12, the catheter 12 and infusion wire (14, 16, 52) may be removed from the patient.

[0029] It will be appreciated that the system 10 may be set up in the aspiration

configuration of FIG. 2 without ever infusing fluid to the clot 13 by following the identical setup steps discussed above with respect to the fluid infusion configuration except for the alignment of the tube 16 relative to the clot 13 and the catheter 12 (e.g., the tube 16 is initially positioned distal of the clot 13 rather than at the clot 13).

[0030] It will also be appreciated that various steps of the setup method may be modified or omitted as needed to properly distally advance and position the catheter 12, elongate member 14, tube 16, and distal wire 52. For example, rather than utilizing a microcatheter which is advanced over the guidewire, withdrawing the guidewire, advancing the perfusion wire through the microcatheter to the blood clot 13, withdrawing the microcatheter, and then advancing the suction catheter to the blood clot, it is possible, although less preferred, to advance the suction catheter over the guidewire, withdraw the guidewire and then advance the perfusion wire through the suction catheter to the blood clot without ever utilizing the microcatheter.

[0031 ] It will also be appreciated that the system 10 and method disclosed herein reduces the access length to the cerebral clot relative to the access length from the femoral artery. In addition, suction is increased at the location of the blood clot by virtue of the shortened length/path of the catheter 12.

[0032] Turning to FIG. 3, an alternative embodiment of a suction catheter 112 is shown in which the proximal portion 112a of the suction catheter 112 includes a bellows 170. The bellows 170 includes a proximal end 170a and a distal end 170b, and is utilized during aspiration of the system to facilitate proximal and distal axial movement of the elongate member 114 relative to the portion 112c of the catheter 112 distal of the distal end 170b of the bellows section 170 without moving the elongate member 114 relative to the seal 124. Thus, virtually any type of seal 124 appropriate for forming an air tight and fluid tight seal between the elongate member 114 and the catheter 112 may be utilized. For example, it will be appreciated that the elongate member 114 may be solidly connected to the catheter 114 at the proximal end 112a. The proximal portion 112a of the catheter 112 proximal of the proximal end 170a of the bellows 170 may be advanced distally in its entirety along with the proximal end 114a of the elongate member 114. This will cause collapsing of the bellows 170 while the portion 112c of the catheter 112 remains stationary. While the bellows 170 folds and unfolds in an accordion-like manner, other types of collapsing structures could be utilized. [0033] There have been described and illustrated herein several embodiments of a system and a method of removing a blood clot from the intracranial vasculature of a patient. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. While particular types of ports and seals have been disclosed, it will be understood that other types of ports and seals can be used, and that various types of plastic and metal materials may be utilized to make the components of the system of the invention. It is noted that the word "approximately" used herein means the range within (+) or (-) 20 percent of the value which follows the word "approximately". While particular preferred shapes and sizes of catheters, elongate members, and tubes have been disclosed, it will be appreciated that minor modifications to the shapes and sizes of the catheters, elongate members, and tubes which also accomplish the functionality of the system may be utilized. For example, rather than providing the suction catheter with a necked down and a reduced diameter distal portion, the distal portion of the suction catheter could have the same diameter as the remainder of the catheter, and the perfusion wire could be provided a bump on the outer surface of the tube between the proximal opening and the distal openings. If desired, the bump could provide a sliding interference fit with the inside diameter of the suction catheter. In this manner, when fluid is infused through the catheter, the bump will close the distal end of the catheter such that fluid is forced into the proximal opening of the tube and out the distal openings. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.

Claims

WHAT IS CLAIMED IS:

1. A system for use in a blood vessel having a blood clot, the system comprising:

a catheter having a proximal section and a distal section, said proximal and distal sections of said catheter defining a channel therethrough, said distal section of said catheter defining an outlet in fluid communication with said channel and with the blood vessel, said outlet having an outlet diameter;

a wire extending through said channel of said catheter and longitudinally translatable relative to said distal section of said catheter, said wire having a proximal end, a distal end, and a neck portion between said proximal and distal ends and adjacent said distal end, said neck portion having a neck diameter which is substantially less than said outlet diameter;

a tube coupled to said distal end of said wire, said tube having an outer wall which defines at least one proximal opening therethrough, at least one distal opening therethrough, and a fluid path between and in fluid communication with said at least one proximal opening and said at least one distal opening,

wherein, in the blood vessel, said system is configurable to a fluid infusion

configuration in which at least one proximal opening of said tube is disposed inside said channel of said catheter, and at least one distal opening of said tube is disposed at or adjacent the blood clot outside of said catheter, and

wherein, in the blood vessel, said system is configurable to an aspiration configuration in which said neck portion of said wire extends through said outlet and though the blood clot, and said wire is manually operable by a user to longitudinally translate said neck portion proximally and distally relative to said outlet while suction is applied through said catheter to said outlet to translate fluid proximally from the blood clot to said proximal section of said catheter.

2. A system according to claim 1, wherein:

said proximal section of said catheter defines a port in fluid communication with said channel, said port for introducing a fluid to said channel when said system is in said fluid infusion configuration.

3. A system according to claim 1, wherein:

said distal section of said catheter includes a tapered section proximal of said outlet, a portion of said distal section of said catheter proximal to and adjacent said tapered section has a channel diameter, and said outlet diameter is smaller than said channel diameter.

4. A system according to claim 3, wherein:

said outlet diameter is approximately 0.020".

5. A system according to claim 3, wherein:

said outlet has an angled distal end.

6. A system according to claim 3, wherein:

in said fluid infusion configuration, said outlet is disposed between said at least one proximal opening of said tube and said at least one distal opening of said tube.

7. A system according to claim 3, wherein:

in said fluid infusion configuration, a proximal opening of said tube is disposed inside said tapered section of said catheter.

8. A system according to claim 1, wherein:

in said fluid infusion configuration, said neck portion is disposed proximal of said outlet.

9. A system according to claim 1, wherein:

said catheter has an inner diameter no larger than approximately 0.040".

10. A system according to claim 1, wherein:

said at least one distal opening of said tube includes two distal openings longitudinally offset from each other.

11. A system according to claim 1, wherein:

said at least one distal opening of said tube includes four distal openings longitudinally offset from each other.

12. A system according to claim 1, wherein:

said at least one proximal opening and said at least one distal opening are circular or oval in shape.

13. A system according to claim 1, wherein:

a respective proximal opening of said tube is larger than a respective distal opening of said tube.

14. A system according to claim 1, further comprising:

a second wire coupled to said tube distal of said at least one distal opening of said tube.

15. A system according to claim 14, further comprising:

a coil situated about said second wire.

16. A system according to claim 1, wherein:

the blood vessel is part of an intracranial vasculature.

17. A system according to claim 1, wherein:

said proximal section of said catheter defines a proximal end, said proximal end includes a seal, and said elongate member extends through said seal and into said catheter and is longitudinally translatable relative said distal section of said catheter.

18. A system according to claim 1, wherein:

said proximal section of said catheter includes a collapsible section which folds and unfolds as said wire is longitudinally translated relative to said outlet.

19. A system for removing a blood clot in the intracranial vasculature of a patient, the system comprising:

a catheter of approximately 35 cm in length and no more than approximately 0.040 inches in diameter which extends from an access incision in the carotid artery of the patient to adjacent the blood clot, said catheter adapted to being coupled to a fluid source for infusing fluid through said catheter to the blood clot and also being adapted to being coupled to a source of suction in order to aspirate the blood clot into said catheter; and

a wire extending through a distal end of said catheter and movable relative to a distal portion of said catheter for agitating the blood clot.

20. A system according to claim 19, wherein:

said wire has a distal portion of substantially smaller diameter than another portion of said wire.

21. A method for removing a blood clot in the intracranial vasculature of a patient, comprising: incising the carotid artery of the patient;

distally advancing a guidewire through the incision in the carotid artery toward the blood clot;

distally advancing a microcatheter over the guidewire toward the blood clot;

withdrawing the guidewire from the carotid artery;

distally advancing a second wire through the microcatheter toward the blood clot;

withdrawing the microcatheter from the carotid artery;

distally advancing a suction catheter over the second wire to a position adjacent the blood clot;

applying suction though the suction catheter to move fluid from the blood clot proximally through the suction catheter.

22. A method according to claim 21, wherein:

prior to distally advancing the guidewire, a guiding sheath is inserted into the carotid artery.

23. A method according to claim 21, wherein:

the suction catheter has a distal outlet, the distal outlet has an outlet diameter, and the second wire includes a neck portion having a neck diameter, the neck diameter substantially smaller than the outlet diameter, and

wherein, during suction, the neck portion is longitudinally translated proximally and distally through the distal outlet and the blood clot to mechanically agitate the blood clot and to prevent clogging of fluid in or adjacent the suction catheter.

24. A method according to claim 23, further comprising:

prior to applying suction, positioning the neck portion proximal of the outlet, infusing a fluid through the suction catheter to the blood clot, and distally translating the neck portion to extend through the outlet.

25. A method according to claim 21, wherein:

said second wire has a tube coupled to its distal end.

26. A method according to claim 25, further comprising:

prior to applying suction to the suction catheter, infusing a fluid through the suction catheter and the tube to the blood clot to dissolve or break up the blood clot.

27. A method according to claim 26, wherein:

the suction catheter includes a tapered section proximal to the distal outlet, and the distal outlet includes a diagonally cut distal end.

28. A method for removing a blood clot in the intracranial vasculature of a patient, comprising: incising the carotid artery of the patient;

distally advancing a suction catheter over the guidewire to a position adjacent the blood clot;

withdrawing the guidewire from the carotid artery;

distally advancing a second wire through the suction catheter and into the blood clot; applying suction though the suction catheter with said second wire in place in the suction catheter to move fluid from the blood clot proximally through the suction catheter.

29. A method according to claim 28, wherein said second wire has a tube at its distal end, said method further comprising:

prior to applying suction through the suction catheter, infusing a fluid through the suction catheter and the tube to the blood clot to expedite dissolving or breaking up the blood clot.

30. A method according to claim 28, wherein the suction catheter has a distal outlet having an outlet diameter, and the second wire includes a neck portion having a neck diameter, the neck diameter substantially smaller than the outlet diameter, said method further comprising:

while applying suction, longitudinally translating the neck portion of the second wire through the distal outlet of the suction catheter to mechanically agitate the blood clot.