US20070161963A1 - Aspiration thrombectomy catheter system, and associated methods - Google Patents

Abstract

An aspiration thrombectomy catheter system includes an aspirator and an aspiration catheter for insertion in a blood vessel. The catheter has a shaft with a proximal end for connection with the aspirator and a tapering distal end with a tip for insertion in the vessel. A plurality of aspiration ports are arranged in sets along the tapering distal end, for aspirating thrombus from the vessel. At least one aspiration lumens within the shaft conducts thrombus from the vessel, through the aspiration ports, to the aspirator. Variably sized or shaped ports provide differing aspiration vectors for enhanced thrombus removal. The aspiration thrombectomy catheter additionally provides for uniform drug dispersion at a thrombotic area, alone or in combination with aspiration of the thrombus. In the event of an adverse reaction, drug dosage may be easily reduced by aspirating dispersed drugs back into the catheter.

Description

RELATED APPLICATIONS
• This application claims priority of U.S. Provisional 60/757,790, filed Jan. 6, 2005 and incorporated herein by reference.
BACKGROUND
• Coronary artery thrombus may be a cause of, or a culprit in, acute coronary syndromes such as acute myocardial infarction and unstable angina. The presence of thrombus in the coronary artery, accompanying a significant artherosclerotic plaque narrowing, complicates optimal revascularization by percutaneous techniques such as angioplasty or stenting.
• Distal embolization of thrombus into the distal coronary artery macro and micro circulation, which may for example occur during balloon angioplasty or coronary stenting, results in reduced TIMI (Thrombolysis in Myocardial Infarction) flow. Reduced TIMI flow or flow grade has been demonstrated to reduce patient outcomes in such studies as the PAMI (Primary Angioplasty in Myocardial Infarction) stent trials and the CADILLAC (Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications) clinical trials.
• Dealing with coronary thrombus in these situations has been the subject and focus of many pharmacologic and endovascular techniques. Endovascular techniques of thrombus removal by thrombectomy devices have been well studied and several existing devices have been tried, such as the Possis AngioJet® System, which theoretically allows a physician to infuse medication directly into a thrombus and/or remove the thrombus through power pulse aspiration. Unfortunately, clinical trials conducted with the AngioJet® System have failed to demonstrate an advantage over previous techniques for treating coronary thrombus, such as balloon angioplasty prior to implantation of a stent.
• Other means of treating coronary thrombus include passive aspiration by end-hole aspiration thrombectomy catheters such as the Export aspiration catheter. The Export aspiration catheter consists of a 5 French monorail catheter connected to an evacuated 20 ml syringe used to remove thrombotic debris. While rather extensively used, the efficacy of this treatment is limited by thrombus plugging the end hole during the procedure. Other, newer passive aspiration catheters like the Diver CE (manufactured by V3, Inc.) include a few side holes along the catheter body near the end of the aspiration catheter; yet such catheters are apt to plug with only slightly more thrombus than necessary to plug the passive export catheter.
SUMMARY
• The aspiration thrombectomy catheter system disclosed herein may overcome problems associated with prior devices to provide thrombus removal and drug dispersion in coronary arteries or arterial conduits, such as saphenous vein bypass grafts or peripheral arteries.
• In one embodiment, an aspiration thrombectomy catheter system includes an aspirator and an aspiration catheter for insertion in a blood vessel. The aspiration catheter has a shaft with (a) a proximal end for connection to the aspirator and (b) a tapering distal end with a tip for insertion in the vessel. A plurality of aspiration port sets, each having a plurality of ports for aspirating thrombus from the vessel, are arranged along the tapering distal end. At least one aspiration lumens within the shaft conducts thrombus from the vessel, through the aspiration ports, to the aspirator.
• In one embodiment, a method for aspirating thrombus includes advancing an aspiration catheter within a vessel until at least a distal set of aspiration arranged along a distal portion of tapering catheter tip is proximate a thrombus. Aspiration forces are applied through at least the distal set of aspiration ports to suction at least a first portion of the thrombus into a first aspiration lumens. The aspiration catheter is advanced through unaspirated thrombus and aspiration forces are applied via at least one second set of aspiration ports arranged proximal to the distal set of aspiration ports, along the tapering catheter tip, to suction at least a second portion of the thrombus into the aspiration catheter.
• In one embodiment, a method for aspirating thrombus includes advancing an aspiration catheter within a vessel to an occluding thrombus. One or more lytic agents are dispersed from a first catheter lumens to the thrombus via a first set of ports opening into the first catheter lumens. Aspiration forces are applied to the thrombus via at least a second set of ports, the second set of ports conducting aspirated thrombus into a second catheter lumens.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 depicts one embodiment of an aspiration thrombectomy catheter system including an aspiration thrombectomy catheter.
• FIG. 2 shows the aspiration thrombectomy catheter ofFIG. 1 in a section of artery.
• FIG. 3 is a flow-chart illustrating a method of aspirating thrombus, for example using the aspiration thrombectomy catheter ofFIG. 1.
• FIG. 4 illustrates drug dispersion proximate a thrombus, with the aspiration thrombectomy catheter ofFIGS. 1 and 2.
• FIG. 5 is a flow-chart showing a method of delivering thrombolytic drugs, for example using the aspiration thrombectomy catheter ofFIGS. 1,2 and4.
DETAILED DESCRIPTION
• It is appreciated that the present teaching is by way of example, not limitation. The illustrations herein are not limited to use or application with a specific type of aspiration thrombectomy catheter. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, it is appreciated that the principals herein may be equally applied in other embodiments of aspiration thrombectomy catheters.
• For example, for ease of discussion, aspirationthrombectomy catheter system100 is described herein below with respect to removal of coronary thrombus; however, those skilled in the art will recognize, after reading and fully appreciating the present disclosure, thatsystem100 may be equally applied for enhanced thrombus removal elsewhere in the circulatory system. For example,system100 may be applied in:
• • Removal of thrombus in the carotid circulation, both extra-cranial and intra-cranial;
  • Removal of visceral thrombus, for example from arteries supplying digestive organs and/or from arteries supplying the kidneys;
  • Removal of peripheral vascular thrombus, for example from the legs;
  • Thrombus removal in surgically created arterial venous fistulas for hemodialysis, for example using cross-catheter thrombectomy;
  • Removal of thrombus from synthetic dialysis access grafts;
  • Removal of thrombus from surgically created synthetic or native vein bypass grafts (both harvested and transplanted and in-situ vein grafts);
  • Removal of thrombus from a stent;
  • Removal of stenosis from a stent or surgically created fistula, dialysis access or vein bypass graft;
  • Isolated and uniform drug dispersion through aspiration ports, e.g., during any of the above procedures; and
  • Readily customizable dosage (e.g., amplification and/or reduction) as a function of real-time patient response to dispersed drugs.
As used herein, the term “vessel” refers to any circulatory conduit, including but not limited to the aforementioned arteries, veins, fistulas, grafts and stents.
• FIG. 1 shows an aspirationthrombectomy catheter system100.System100 includes acatheter102 having ashaft104.Shaft104 has one or more proximal ends (not shown; see howeverFIG. 4) for connection with one or more aspirators, and a distal end orsection106. As shown inFIG. 1, adistal end106 has a plurality of aspiration holes or ports108, arranged in a plurality ofsets110. As used herein, a set of ports indicates two or more ports grouped in close proximity to one another. In one embodiment,distal section106 includes threesets110A-110C having ports108A-C, respectively.Sets110A-C may be arranged asdistal set110A,middle set110B andproximal set110C, withrespective ports108A (distal ports),108B (middle ports) and108C (proximal ports) opening into one or more aspiration port channels/lumens.
• Distal end/section106 ofcatheter102 is for example inserted into the circulatory system on a needle and advanced to an occlusion in a small, medium or large artery; therefore,system100 may be sized for the desired use (as used herein, the terms “occlusion” and “occluding” may refer to partial or complete occlusion or occluding of a vessel).Distal section106, and optionally all or a portion ofshaft104, may be formed or coated with a smooth or low-friction material such as Teflon, to facilitate advancement ofcatheter102. Further,catheter102 may be configured as a single or a dual aspiration catheter. Whencatheter102 is a single lumen aspiration catheter, an aspirator attaches to the proximal end of the catheter. Whencatheter102 is a dual lumen aspiration catheter,shaft104 branches to form two proximal ends for connection with one or more aspirators.
• Distal section106 tapers proximally to distally from ashoulder116 to atip118.Tip118 and/or a portion or all ofdistal section106 is for example formed or covered with asoft material107 to minimize vessel trauma, while part or all ofshaft104 is stiffer, to prevent kinking and facilitate advancement and torqueability ofcatheter102 within a vessel, such as a coronary artery.Walls120 ofshaft104, and optionallydistal section106, for example include medically acceptable rigid polymers, co-polymers or metals, such as plated or unplated stainless steel, ELGILOY, platinum, a shape-memory alloy such as nitinol, or combination thereof. In one embodiment,shaft104 is a flexible tube reinforced with one or more of the above polymers, co-polymers and/or metals. Such reinforcement materials may be wired, braided or coiled through or withinshaft104. Proximal-to-distal flexibility may be increased by decreasing braid, coil or wire density from proximal end/s todistal section106 ortip118. A degree of reinforcement withindistal section106 for example provides for a soft-tippedcatheter102 that resists twisting or wrapping oftip118 and/ordistal section106 during advancement or rotation.
• Awire122 guidescatheter102 in a vessel, e.g.,artery200,FIG. 2.Catheter102 may be a monorail or fixed wire catheter (e.g., to allow for smaller diameters) or an over-the-wire catheter. That is,wire122 may be fixed withcatheter tip118, with a set distance betweentip118 and awire tip124, orcatheter wire122 may be a separate and unattached guide wire over whichcatheter102 rides.
• In one embodiment,catheter102 is an over-the-wire catheter (for ease of illustration, the wire lumen of the catheter is not shown). Over-the-wire catheters often ride in the center of straight segments of an artery. Ascatheter102 advances into an arterial thrombus, vacuum forces provided at a certain magnitude throughports108A-C of taperingdistal section106 aspirate thrombus, for example from the inside-out, viaports108A,108B and108C. Asdistal section106 encounters thrombus, vacuum forces provided throughports108A aspirate nearby thrombus. As thrombotic material is generally cohesive, thrombus drawn intoports108A (and/or108B,108C) may pull additional thrombus intocatheter102. Portions of thrombus that are not pulled intocatheter102 by cohesion, e.g., portions that are too far away for aspiration throughports108A, may be drawn inward and closer to middle and/orproximal ports108B,108C, by vacuum forces. As middle/proximal ports108B,108C are positioned on wider portions ofdistal end106 thanports108A, aspiration is further facilitated ascatheter102 advances within the vessel and the distance between the vessel walls and adhered thrombus, andports108A-108C successively decreases. Increased proximity between remaining thrombus andports108B,108C (e.g., provided both by inward pull throughports108A and the taper of distal section106), for example allows the same magnitude of vacuum force applied throughdistal ports108A to effectively aspirate remaining thrombus throughports108B,108C. The effective surface area of thrombus aspirated is thereby increased.
• The tapering design ofcatheter102 may further provide increased thrombus-to-port contact or proximity over the prior art. For example, prior art French catheters have essentially the same diameter from proximal end to distal end. Aspiration ports of such a prior art catheter are therefore located farther and farther from remaining, unaspirated thrombus as the catheter advances in the artery. A prior art catheter of essentially uniform diameter may be unable to effectively remove intimal thrombus, whereas the tapering design ofcatheter102 provides increasing proximity between distal-to-proximal aspiration ports and medial-to-intimal thrombus, respectively, ascatheter102 advances therethrough. For example, thrombus that is pushed or wedged away from distal aspiration ports, such as ports108 (e.g., pushed against the vessel wall by a guide wire or fixed wire) may be aspirated via middle orproximal ports108B,108C ofcatheter102, whereas the prior art French catheter may be unable to aspirate the displaced thrombus due to the increased port-to-thrombus distance. In addition,Catheter shoulder116 may trap unaspirated thrombus, providing an extended opportunity for aspiration throughproximal ports108C, e.g., during withdrawal of the catheter.
• As shown inFIG. 1,catheter102 has a proximal, or first aspiration lumens112 (hereinafter referred to as first lumens112) for aspiration throughproximal ports108C, and a middle-distal, or second aspiration lumens114 (hereinafter referred to as second lumens114) for aspiration through middle anddistal ports108B,108A. Distal, middle andproximal ports108A,108B and108C may be sized, shaped and/or oriented differently from one another.FIG. 1 illustrates rounddistal ports108A and elliptical middle andproximal ports108B,108C of differing size and orientation. However, other arrangements of port shapes and sizes are within the scope hereof. For example, all ofports108A-C may be elliptical, withports108B,108C of middle andproximal sets110B,110C differing in orientation and/or size fromdistal ports108A ofset110A. Alternately, ports ofsets110A-C may be similarly sized and shaped, but differently oriented. Such variation in port size, shape and/or orientation providesystem100 with a variety of vortices and aspiration vector forces (directions and/or magnitudes), for enhanced thrombus removal over prior art catheters having fewer ports of essentially the same size, shape and orientation. Sets of small ports for example enhance aspiration by the Venturi effect, speeding flow of aspirated thrombus intoaspiration lumens112/114, while larger port sets allow for aspiration of larger thrombotic particles.
• FIG. 2 showssystem100 in a section ofartery200 partially occluded bythrombus202. Aswire122 andcatheter102 advance throughthrombus202, aspiration port sets110A-110C successively contact or come into proximity with innermost, middle andintimal layers204,206,208 ofthrombus202. Aspiration of innermost, middle and intimal layers204-208 may occur as illustrated by directional aspiration arrows210. Aspiration is facilitated by increased thrombus-to-port contact or proximity provided bycatheter102, thus facilitating removal of a greater thrombus burden as the catheter advances through the vessel. The plurality ofports108A-C may also minimize plugging by organized or large thrombus aggregates, as is seen with prior art end-hole catheters or prior art catheters having fewer side ports.
• The tapered design ofcatheter102 may reduce distal embolization of thrombus. For example, as a catheter advances through thrombus, portions of the thrombus may be loosened, but not aspirated. Prior art designs having substantially uniform catheter or distal section diameter may not come into close enough proximity to aspirate portions of thrombus clinging to the intima, for example; however, this intimal thrombus may be loosened. The loosened thrombus may break free and embolize in distal arterial conduits. The tapering shaft ofcatheter102 may reduce this distal embolization becauseaspiration ports108A-C come closer to the vessel walls and any thrombus clinging thereto as the catheter advances. Thrombus loosened during aspiration byports108A or108B is for example aspirated whenports108C come into proximity or contact with the loosened thrombus.
• System100 may also enhance thrombectomy when utilized in a curved section of artery. Aspiration port sets110A-C approach thrombus on an arterial wall in closer and closer succession, due to the tapering design ofcatheter102. Thus,catheter102 may thus also removethrombus202 medially-to laterally in a curved section of artery, as described herein above with respect toFIG. 2.
• FIG. 3 is a flow chart illustrating amethod300 of aspirating thrombus. An aspiration catheter, such ascatheter102 onwire122, is inserted into an artery, instep302. A tapering distal end of the catheter, e.g., end106 ofcatheter102, is advanced into the thrombus, instep304. Thrombus is aspirated through distal aspiration ports of the catheter and through an aspiration lumens, forexample ports108A andsecond lumens114, instep306. As the catheter is advanced further into the blocked artery, middle ports such asports108B are brought into contact with or proximal to unaspirated portions of the thrombus, instep308. These portions are aspirated through an aspiration lumens, such assecond lumens114, via the middle ports, instep310.Catheter102 is advanced yet further into the blocked artery, such that proximal ports of the catheter, e.g.,ports108C, are brought into contact with or proximal to remaining portions of the thrombus that were not aspirated through the middle ports, instep312. These remaining portions of thrombus are aspirated through an aspiration lumens such asfirst lumens112, via the proximal aspiration ports, instep314.
• Continued aspiration during withdrawal ofcatheter system100 may further enhance thrombus removal. Once the catheter has traveled past thrombus, it may aspirate remaining thrombus during withdrawal back through the artery.Catheter102 may, for example, trap remaining thrombus between thecatheter shoulder116 orshaft104 and the arterial wall during an antegrade pass. The trapped thrombus may then be aspirated through proximal-to-distal ports108C-108A as the catheter is withdrawn. Accordingly, the catheter is advanced until aspiration ports (such as port sets110A-110C) have passed through the thrombus, instep316. The catheter is withdrawn back through any remaining thrombus, instep318. The proximal, middle and distal aspiration ports aspirate remaining thrombus, instep320.
• Steps302-320 need not be performed in the order described in connection withFIG. 3. For example, thrombus may be aspirated through aspiration ports whilecatheter102 is simultaneously and continually advanced through a thrombus. Also, not all of steps302-320 need necessarily be performed for effective thrombus removal. For example, if thrombus is completely removed during an antegrade pass therethrough, it may not be necessary to aspirate while withdrawingcatheter102.
• The proximal end or ends ofcatheter102 are connectable with an infusion device, such as a syringe, allowing use ofthrombectomy catheter system100 in thrombolysis, for example to lyse deep and superficial venous thrombi, or in cross-catheter thrombolysis in surgically created arterial venous fistulas. A lytic agent or agents, e.g., Reteplase or Alteplase, is infused viaaspiration lumens112 and/or114, for precise and uniform dispersion throughports108A-108C.FIG. 4 depicts an aspirationthrombectomy catheter system400 for removing thrombus from partially occludedvessel200.Vessel200 is for example blocked bythrombus202 as described above with respect toFIG. 2.Catheter102 is inserted intovessel200 and advanced tothrombus202.Catheter102 may again be an over-the-wire or a fixed wire catheter. In one embodiment,catheter102 is a fixed wire ormonorail catheter102, withwire122 securely formed with catheter tip118 (seeFIG. 1).Wire122 guidesdistal section106 to and/or partially throughthrombus202, where aspiration may be applied as previously described.
• Optionally or additionally,catheter102 connects to a drug dispenser or drug delivery apparatus, such as a gravity flow system, an automated or manually operable pump, a syringe or other intravenous drug dispenser. Such a dispenser is illustratively shown inFIG. 4 as a syringe402 (not to scale). Oncedistal section106 is positioned as desired, relative to the thrombus, lytic agents are for example delivered throughlumens112 and/or114 and out one or more of port sets110A-110C, as indicated bydispersion arrows404.System400 thus provides isolated drug delivery with uniform dispersion from eachport108A-108C, at the occluded/thrombotic area. Alternately,system400 provides targeted drug delivery via selected ports or port sets108,110, while remaining ports or port sets may be used in aspirating loosened thrombus, delivering complementary lytic agents, e.g., in sequence, or reducing dosage in the event of overdose or adverse patient reaction.
• In one embodiment,lumens114 connects with or extends intotubing406 which in turn connects tosyringe402.Tubing406 for example conducts a thrombolytic, antibiotic or otherwise therapeutic drug fromsyringe402, throughlumens114, toproximal ports108C. Should an adverse reaction such as bleeding occur, dosage may be quickly reduced by aspirating the delivered drug back throughproximal ports108C, for example by drawing back onsyringe402. It will be understood thatlumens112 may likewise connect, viatubing408, to a drug or lytic agent dispenser or delivery system such as a second syringe, to facilitate delivery of desired drug combinations or sequences, e.g., via middle anddistal ports108B,108A. Likewise, one oflumens112,114 may connect viatubing406,408 with an aspirator while the other oflumens112,114 connects with the drug dispenser. In the case of an adverse drug reaction, dosage may be quickly reduced by aspirating drugs released via one set ofports110 back through another set ofports110. For example, lytic drugs delivered tolumens114 and dispersed throughproximal ports108C may be aspirated back through distal andmiddle ports108A,108B, in communication withlumens112. Aspirationthrombectomy catheter system400 may also be used to alternately or simultaneously disperse lytic agents and remove/aspire thrombus loosened by the lytic agents. Likewise, a combination ofports108A-C may be used in aspiration or drug dispersion.
• FIG. 5 is a flowchart illustrating onemethod500 for removing thrombus with an aspiration thrombectomy catheter. Instep502 an aspiration thrombectomy catheter is inserted into a vessel. Instep504, the catheter is advanced to a thrombus. In one example ofsteps502,504,catheter102 is inserted into an artery and advanced untildistal section106 contacts or is proximate the thrombus. When the catheter is in position, e.g.,distal section106 is proximate or contacting the thrombus, drugs are dispersed, instep506. In one example ofstep506, drugs are applied totubing406 via a drug dispenser. Drugs travel intolumen112 and out ofports108C.
• Thepatient undergoing method500 is monitored, instep508, e.g., for bleeding or other adverse reactions to lytic drugs. If (decision510) an adverse reaction occurs, released drugs are aspirated, instep516. In one example ofstep516, upon determining that an overdose or adverse reaction has occurred, released lytic drugs are aspirated back intocatheter102 via distal andmedial aspiration ports108A,108C.Lumen114, in contact withports108A,108C, connects withtubing408 which in turn connects with an aspirator, such as a syringe. The aspirator or syringe is activated to “vacuum” the lytic drugs from the vessel.
• Dotted box517 indicates optional steps during or in combination withaspiration step516. Inoptional step518, the catheter is advanced until all aspiration ports have passed through the thrombus. Instep520, the catheter is withdrawn through the thrombotic area.Steps518,520 may be repeated as desired to facilitate aspiration of a thrombolytic agent that has dispersed within the vessel, or to aspirate thrombus loosened by the thrombolytic agent, as described below.
• Returning tomethod500, if (decision510) there is no adverse reaction or overdose and if (decision512) drug delivery is complete,method500 continues withdecision514. If (decision514) thrombus is to be aspirated, aspiration commences instep516.Optional steps518,520 may be repeated until the desired or maximum amount of thrombus has been removed from the vessel. In one example of steps516-520, where aspiration is desirable,tubing404 is disconnected from the aforementioned drug dispenser or delivery system, e.g.,syringe402,FIG. 4, is switched to an aspiration mode. Ascatheter102 is advanced through (step518) and withdrawn from (step520) the thrombotic area, vacuum forces are applied viaaspiration ports108A,108B and108C until the thrombus is satisfactorily removed from the vessel walls. Once the thrombus is satisfactorily aspirated, the catheter is removed, instep522. In one example ofstep522,catheter102 is withdrawn from the body of apatient undergoing method500.
• In one example of steps506-522, a thrombolytic agent is dispersed via distal port set110A,FIG. 1. As noted, distal port set110A may open into a lumens independent of the lumen or lumens associated with middle and proximal port sets110A,110B. If desired, a second thrombolytic agent is dispersed via middle or proximal port sets110A,110B. The second thrombolytic agent may be dispersed synchronously with the agent dispersed viadistal ports108A, or the two agents may be alternated or pulsed to achieve a desired drug combination or amount proximate the thrombus.
• When drug delivery, or a drug delivery cycle, is complete, thrombus loosened by drug therapy is for example aspirated as described above, through one or more of port sets110A-110C.Catheter102 may be advanced and withdrawn back and forth through the thrombotic region during (or interspersed with) aspiration), to enhance thrombus removal.Catheter102 may likewise be rotated such that port sets110A-C alongdistal section106 vacuum the entire inner circumference of the vessel. When thrombus is satisfactorily removed,catheter102 is withdrawn from the patient's body,step522.
• Although not shown inFIG. 5 (for ease of illustration), it will be recognized thatdrug delivery step506 and aspiration steps516-520 may be repeated as desired prior to removal of catheter102 (step522). For example, wheredecision516 pertains to one of multiple drug delivery cycles,method500 may move from aspiration steps516,518 or520 back to drug dispersion atstep506.
• Changes may be made in the above systems and structures without departing from the scope thereof. It should thus be noted that the matter contained in the above description and/or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover generic and specific features described herein, as well as all statements of the scope of the present system and structures, which, as a matter of language, might be said to fall therebetween.

Claims (20)

1. An aspiration thrombectomy catheter system, comprising:

an aspirator; and

an aspiration catheter for insertion in a blood vessel, the aspiration catheter having:

a shaft with (a) a proximal end for connection to the aspirator and (b) a tapering distal end with a distal tip for insertion in the vessel;

a plurality of aspiration port sets arranged along the tapering distal end, each of the aspiration port sets having a plurality of ports for aspirating thrombus from the vessel, and

at least one aspiration lumens within the shaft, for conducting aspirated thrombus from the vessel, through the aspiration ports, to the aspirator.

2. The system ofclaim 1, wherein the ports of each aspiration port set differ in one or both of size and shape.

3. The system ofclaim 2, the differently sized or shaped aspiration ports providing differing vector forces for aspiration of thrombus.

4. The system ofclaim 3, the differently sized or shaped aspiration ports including small, medium and large ports for producing Venturi forces of varying strength to aspirate the thrombus into the lumens.

5. The system ofclaim 1, the aspiration catheter comprising a dual aspiration catheter having a first aspiration lumens and a second aspiration lumens.

6. The system ofclaim 5, the plurality of aspiration port sets comprising a proximal port set opening into the first aspiration lumens, and a middle and a distal port set opening into the second aspiration lumens;

wherein the first aspiration lumens conducts aspirated thrombus from the proximal port set to the aspirator and the second aspiration lumens conducts aspirated thrombus from the middle and distal port sets to the aspirator or a second aspirator.

7. The system ofclaim 6, further comprising a first tube connecting the first lumens to the aspirator and a second tube connecting the second lumens to the aspirator or the second aspirator.

8. The system ofclaim 1, the shaft comprising a shoulder defining a taper of the shaft to the distal tip.

9. The system ofclaim 1, further comprising a dispenser for dispersing lytic agents through one or more of the aspiration port sets to the thrombus.

10. A method for aspirating thrombus from a vessel, comprising:

advancing an aspiration catheter within the vessel until at least a distal set of aspiration ports arranged along a tapering catheter tip is proximate a thrombus;

applying aspiration forces through at least the distal set of aspiration ports to suction at least a first portion of the thrombus into a first aspiration lumens;

advancing the aspiration catheter through unaspirated thrombus; and

applying aspiration forces via at least one second set of aspiration ports arranged along the tapering catheter tip and proximal to the distal set of aspiration ports, to suction at least a second portion of the thrombus into the aspiration catheter.

11. The method ofclaim 10, further comprising withdrawing the catheter through the thrombus while aspirating through one or more of the distal and the at least one second set of aspiration ports.

12. The method ofclaim 12, wherein applying aspiration forces through the distal set of ports comprises activating a first aspirator and applying aspiration forces through the at least one second set of ports comprises activating a second aspirator.

13. The method ofclaim 12, further comprising dispersing lytic agents at the thrombus through one or more of the distal set of aspiration ports and the at least one second set of aspiration ports, prior to applying the aspiration forces.

14. The method ofclaim 12, wherein advancing the aspiration catheter comprises advancing the aspiration catheter over a guide wire.

15. The method ofclaim 10, wherein suctioning at least a second portion of the thrombus into the aspiration catheter comprises suctioning at least the second portion into a second aspiration lumens.

16. A method for aspirating thrombus from a vessel, comprising:

advancing an aspiration catheter within the vessel to an occluding thrombus;

dispersing one or more lytic agents from a first catheter lumens to the thrombus via a first set of ports opening into the first catheter lumens; and

applying aspiration forces to the thrombus via at least a second set of ports, the second set of ports conducting aspirated thrombus into a second catheter lumens.

17. The method ofclaim 16, further comprising repeating the steps of dispersing and applying, to loosen and remove the thrombus from the vessel.

18. The method ofclaim 16, further comprising applying aspiration forces to the thrombus via a third set of ports, the third set of ports differing from the second set of ports in one or both of size and shape.

19. The method ofclaim 18, the different sizes or shapes of the second and third sets of ports providing multiple aspiration vortices for removing the thrombus from the vessel.

20. The method ofclaim 18, the third set of aspiration ports opening into the second catheter lumens.

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