WO1998044982A1

WO1998044982A1 - Percutaneous aspiration catheter system

Info

Publication number: WO1998044982A1
Application number: PCT/US1998/005411
Authority: WO
Inventors: Lucas S. Gordon
Original assignee: Scimed Life Systems, Inc.
Priority date: 1997-03-20
Filing date: 1998-03-19
Publication date: 1998-10-15
Also published as: US5938645A

Abstract

This invention is a percutaneous aspiration catheter (18) for removing thrombus or other emboli from blood vessels (10), and a method of extracting embolus pieces larger than the diameter of the catheter (18). The percutaneous aspiration catheter has barbs (60) positioned near its end to trap material within the catheter.

Description

PERCUTANEOUS ASPIRATION CATHETER SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. Patent Application, Serial No.

08/449,203 filed on May 24, 1995 and entitled PERCUTANEOUS ASPIRATION

THROMBECTOMY CATHETER SYSTEM, the entire disclosure of which is hereby

incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a device used to break up and extract blood clots or

thrombi which form within blood vessels. More particularly, this invention relates to a

device adapted to break up and extract clots or thrombi which may form within a

coronary artery comprising an improved percutaneous aspiration thrombectomy catheter

system.

BACKGROUND OF THE INVENTION

Approximately 1.2 million Americans suffer heart attacks each year. A large

percentage of the heart attacks are caused by blood clots or thrombi which form within

the coronary arteries. A thrombus is nature's way of stemming the loss of blood from its

pipeline system by corking off an opening into the vascular tree. The biochemical

process which results in thrombus formation is not fully understood. However, in

simple terms, injury to the vascular wall releases chemicals which lead to conversion of

soluble, circulating fibrinogen molecules into a polymeric structure of fibrin. The fibrin

structure is insoluble and arranges itself into a three dimensional network of meshed

strands which entraps red blood cells. The individual strands are approximately 0.2

NOT FURNISHED UPON FILING

collateral blood vessels and flow which can provide the necessary oxygen.

Coronary artery bypass graft (CABG) surgery is a surgical method for bypassing

coronary arteries which, because of narrowing or obstruction, are unable to supply

adequate oxygen to heart muscle. In recent years, direct administration of chemical

lysing agents into the coronary arteries has shown to be of some benefit to patients who

have thrombosed coronary arteries. In this procedure, a catheter is placed immediately in

front of the blockage and a drip of streptokinase is positioned to be directed at the

upstream side of the thrombus. Streptokinase is an enzyme which is able in time to

dissolve the fibrin molecule. This procedure can take several hours and is not always

successful in breaking up the thrombus. Furthermore, it can lead to downstream

thrombus fragments (emboli) which can lead to blockage of small diameter branches.

Auth, U.S. Patent No. 4,646,736, discloses a thrombectomy device that permits rapid

removal of an obstructive thrombus. However, the device is characterized by small catheter tip size and thus is unable to exert significant total force on clot masses. Also, a

clot which is not in good position of purchase on a vessel wall in the "line of fire" of the

rotating wire is not fϊbrinectomized. This is especially true of clots floating free in the-

blood stream, since it is virtually impossible to revolve within these clots in the

absence of a constraint such as fingers.

Further disadvantages to this thrombectomy device include the difficulty of

keeping the clot in the space above the wire during all degrees of rotation as the wire is

moved sideways during rotation, which is sometimes necessary to sweep the arterial

lumen. In fact, sweeping out an entire arterial lumen with a rotating wire is virtually impossible in all but the smallest, i.e., less than 1.5 mm diameter, arteries. An additional

and serious possible disadvantage is that fragments of the clot may be embolized

downstream.

Therefore, there has been a definite need for a thrombectomy device that can be

more effective in sweeping arteries, in removing emboli that are free floating

or not perfectly positioned, and in minimizing fragmentation of clots.

These and other objects of the invention will become apparent from the following

discussion of the invention

SUMMARY OF THE INVENTION

The present invention provides for an improved system for removing thrombus

from blood vessels which includes the following components:

a catheter having proximal and distal ends, designed to be advanced through a

hemostasis valve and guide catheter and over a guide wire for placement of its

distal end at the thrombus, the catheter having at least one lumen passing from

the proximal to the distal end;

the catheter having a guide wire retaining means, which retains the guide wire

within the catheter in a peripheral or non-centered part of the catheter cross-

section. The distal tip of the catheter is angled back from the guide wire retaining

means to allow the catheter to easily follow the guide wire around tight bends and

across restrictions;

suction means in fluid communication with the proximal end of the catheter

for providing vacuum down the catheter lumen to the distal tip, for drawing

thrombus into the lumen; and the lumen terminating in and angled tip at the distal end of the catheter, the

angled tip improving the removal of thrombus adhering to the vessel wall and

reducing clogging of the hole with thrombus.

In another embodiment of the present invention, an improved thrombectomy

catheter and method of use is disclosed. The catheter has barbs located near the distal

end. The barbs may be attached to the catheter or integrally formed with a radio opaque

ring and thereby also serve as a marker band. The ring may have a reverse bend which

provides a channel to retain a guide wire. The barbs provide safety in that any particles

entering the catheter can not float out. The barbs further provide a means of removing

pieces of thrombus which are larger than the diameter of the catheter and which may be

too hard to deform or break apart and be drawn through the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic representation of a bifurcated blood vessel having a blunt tip catheter and guidewire inserted at the point of bifurcation; Fig. 2 is a schematic representation of a bifurcated blood vessel having a catheter with an

unconstrained angled tip and guidewire inserted therein at the point of

bifurcation;

Fig, 3(a) is a schematic representation of a bifurcated blood vessel having a

constrained angled tip catheter and guidewire inserted at the point of bifurcation with the

angled tip of the catheter in one orientation;

Fig, 3(b) is a schematic representation of a bifurcated blood vessel having a

constrained angled tip catheter and guidewire inserted at the point of bifurcation with the angled tip of the catheter in another orientation;

Fig, 4 is a schematic representation of a preferred embodiment of percutaneous

aspiration thrombectomy catheter system, according to the present invention;

Fig, 5(a) is a schematic representation of a preferred embodiment of a ,

percutaneous aspiration thrombectomy catheter system according to the present

invention with a two lumen configuration;

Fig, 5(b) is a cross-section of the percutaneous aspiration thrombectomy catheter

depicted in Fig. 5(a);

Fig. 5(c) is another cross-section of the percutaneous aspiration thrombectomy

catheter depicted in Fig. 5(a);

Fig, 6(a) is a schematic representation of the tip design of a single lumen

percutaneous aspiration thrombectomy catheter according to the present invention showing a variation wherein the distal tip is punched to provide a hole through which the guidewire is inserted;

Fig, 6(b) is a plan view of a schematic representation of the distal tip depicted in

Fig. 6(a);

Fig, 6(c) is a side view of the distal tip depicted in Fig, 6(a) prior to the formation of

the bent tip;

Fig. 6(d) is an end view of the distal tip depicted in Fig. 6(c);

Fig. 7(a) is a cross-sectional representation of a single lumen design of a necked

down distal tip for a percutaneous aspiration thrombectomy catheter depicted in Fig. 5(a)

showing the location of the proximal entry of the guidewire at the distal exit point of the

guidewire; Fig. 7(b) is a longitudinal cross-section of the single lumen design for a necked

down distal tip for the percutaneous aspiration thrombectomy catheter shown in Fig.

7(a) without the insertion of the guidewire;

Fig. 7(c) is a side view of the single lumen design for necked down distal. tip for the

percutaneous aspiration thrombectomy catheter shown in Fig. 7(a) without the insertion

of the guidewire;

Fig. 7(d) is a distal end view of the embodiment shown in Fig. 7(c);

Fig. 8 is a cross-sectional representation of a single lumen off-set tip design for

the percutaneous aspiration thrombectomy catheter according to Fig. 5(a) showing a

distal guidewire exit hole and a thrombus entry port located in the off-set section of the distal tip;

Fig. 9(a) is a schematic representation of the tip design of a preferred

embodiment of a percutaneous aspiration thrombectomy catheter system according to the

present invention with a two lumen configuration and a barb with two points attached to the catheter tip with the barb points oriented distally;

Fig. 9(b) is a plan view of the barb depicted in Fig. 9(a);

Fig. 10(a) is a schematic representation of the tip design of a preferred

present invention with a two lumen configuration and a cutting-blade attached to the

catheter tip with the blade bisecting the thrombus aspiration lumen;

Fig. 10(b) is a plane view of the blade depicted in Fig. 10(a);

Fig. 10(c) is an end view of the distal tip depicted in Fig. 10(a); Fig. 11(a) is a schematic representation of the tip design of a preferred

present invention with a two lumen configuration and an expandable balloon attached to

the catheter tip-near to the distal end; and

Fig. 11(b) is a cross-sectional representation of the distal tip depicted in Fig.

11(a).

Fig. 12(a) is a partially cross-sectioned side view of another embodiment of the

percutaneous aspiration thrombectomy catheter system.

Fig. 12(b) is an end view of the embodiment of Fig. 12(a).

Fig. 13 is a partially cross-sectioned side view of another embodiment of the

percutaneous aspiration thrombectomy catheter system.

Fig. 14 (a) is a partially cross-sectioned side view of further embodiment of the

percutaneous aspiration thrombectomy catheter system.

Fig. 14(b) is an end view of the embodiment of Fig. 14(a).

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, a system for removing thrombus from blood vessels

comprises a catheter having proximal and distal ends, designed to be advanced through a

hemostasis valve and guide catheter and over a guidewire for placement of its distal end

at the thrombus, the catheter having at least one lumen passing from the proximal to the

distal end, and a guidewire retaining means, which retains the guidewire within the

catheter in a peripheral or non centered part of the catheter cross section. The distal tip

of the catheter is angled back from the guidewire retaining means to allow the catheter to

follow the guidewire around tight bends and across restrictions easily. Also, there is suction means in communication with the proximal end of the catheter for providing

vacuum down the catheter lumen to the distal tip, for drawing thrombus into the lumen,

and the lumen terminates in the angled tip at the distal end, the angled tip improving the

removal of thrombus adhering to the vessel wall and reducing clogging of the hole with

thrombus.

Various prior art references on thrombectomy aspiration catheters address the use

of plain, single lumen catheters with a blunt tip over a conventional guidewire. In some

cases the catheters taught there may have side holes (such as, for example, drug infusion

catheters). In-vitro testing has established that single lumen, round bore catheters need

to be at least 0.042" i.d. to effectively remove a thrombus with a 0.009" guidewire down

the middle. When such catheters were placed in a "heart model", it was found that it was

sometimes very difficult to maneuver such a catheter over the wire at a bifurcation. The

blunt tip tended to advance straight and would catch at the bifurcation. Adding an angled tip to the catheter helped in negotiating the bend if the tip was on the inner radius of the curvature. If it was on the outside, it increased the tendency to snag at the

bifurcation. As will be seen, adding a means to capture the guidewire on one side of the

catheter and tapering from that point made it possible to always negotiate a right bend or

bifurcation.

Vacuum is provided using a small diaphragm pump which maintains a steady

vacuum of about 550 millimeters of Mercury vacuum. The use of a pump makes it easy

to advance the catheter tip through the thrombus with a steady vacuum level. Most of

the previous clinical use of thrombectomy catheters used suction applied with a syringe, It has been found that it is difficult to advance the catheter while maintaining steady

vacuum with the syringe.

The angled tip provided for in the present invention provides a greater cross-

sectional area for the thrombus to enter the catheter, increasing the total force (Force =

Pressure X Area) which is applied to the thrombus, increasing the amount and rate of

thrombus removal and reducing the tendency to clog.

Various additional features are contemplated and may be optionally incorporated

into the device of the present invention to improve its overall efficiency and workability.

For example, an exit point for the guidewire allows the guidewire to continue outside of

the catheter in the proximal section, allowing the catheter and guidewire to

separately pass through the hemostasis valve.

It has been found that optimal tracking of the relatively large bore thrombectomy catheter over the small guidewire works best if the wire is held at the outer wall of the catheter tip and the tip is angled back from that point. However, to simplify sealing

around the guidewire it is generally easiest if the guidewire and catheter are passed

through the hemostasis valve separately. This eliminates the need for a separate seal

around the guidewire at the proximal end of the catheter. This is advantageous, as was

shown when an embodiment of the present invention was tested with a seal at the

proximal end of the catheter through which a guidewire was passed. To advance the

catheter over the guidewire with the vacuum on, the guidewire seal had to be loosened.

Air was immediately pulled through the seal and into the catheter and rapidly filled - li ¬

the blood collection bottle. Also, there was a lower level of vacuum in the inner lumen at

the catheter tip. The presence of air in the catheter can also be a problem if it is desired to

infuse medicants through the catheter.

Since coronary thrombi are often initiated by a lesion on the vessel wall, it is sometimes

advantageous to dilatate the lesion with a balloon catheter, thereby reducing the

constriction and reducing the chances for another thrombotic event. Many examples of

these devices are known to the art. To facilitate this dilatation procedure, an expandable

dilatation balloon may be incorporated integral to thrombectomy catheter at or near the

distal tip. This allows the operator to easily dilatate the lesion before or after aspirating

the thrombus utilizing a single device.

A situation occasionally occurs when a large, very firm thrombus is aspirated into

a catheter tip but is not fragmented and withdrawn down the catheter. In this situation,

there is a need to positively retain the thrombus within the catheter tip. To accomplish

this a barb incorporating one or more-points can be placed within the catheter lumen at

the distal tip. By orienting the points proximally, the thrombus is effectively retained and

prevented from escaping.

Another way to handle this situation is to place a blade within the distal tip of the

catheter lumen with the sharp edge facing distally. The blade cuts the large thrombus

and allows the pieces to more easily pass through the catheter lumen.

A bottle or bag may be provided between suction means and the catheter for

collecting blood and thrombus as it is removed by the suction means. Further, a filter

may be provided between the suction means and the catheter to separate the solid

thrombus from the liquid blood, said filter preferably being located-within the collecting bottle. The filter provides a convenient way to visualize the amount of clot removed and

makes it easy to take a sample for analysis.

A guidewire retaining means may be provided, comprising a second lumen

extending proximally from the distal end of the catheter, terminating prior to the point

where the catheter passes through the hemostasis valve.

A variation of the device of the present invention wherein the guidewire retaining

means comprises a second lumen has both advantages and disadvantages. Advantages include:

no holes penetrating through the main aspiration lumen to reduce vacuum

to the tip and suck additional blood through; and

slight ease in loading the catheter on the guide wire.

A "partial rapid exchange" design can be accomplished using a long guidewire lumen

with a slit from the proximal end, extending to several inches (less than 10 cm) from the

distal end. The cardiologist user can load the catheter over the short rapid exchange

length guidewire and insert both the wire and catheter through the guide sheath to the

coronary arteries. At that point, the guidewire extends distally out of the catheter and

through the thrombus. The catheter is then advanced. To remove the catheter, it is

withdrawn over the wire to the point where the guidewire lumen is exposed and then the

catheter is peeled off of the guidewire as it is withdrawn to the end of the slit. The last

two inches are then pulled off. At this point another rapid exchange catheter can be

advanced over the guidewire but not another thrombectomy catheter. Of course, the

thrombectomy catheter can be used with any standard length guidewire. The main disadvantage of the two lumen design is that a slightly larger diameter

is required due to the presence of the added internal wall.

The proximal end of the second guidewire lumen may be provided with a slit for

a portion of its length from the proximal end toward the distal end to allow for the

peeling of the catheter from the guidewire, as the catheter is removed from the

vasculature over the guidewire. Also, the device of the present invention may be

configured as a single lumen catheter where the guidewire retaining means is

comprised of two holes in the lumen, one at the distal end and one intermediate between

the distal and proximal ends allowing the guidewire and catheter to pass separately

through the hemostasis valve.

This latter design is the simplest to manufacture but it has some functional

problems as described above for the double lumen configuration.

The end of the catheter can be necked down for a distance before the guidewire

exit hole at the distal end of the catheter. The reason for this necking down is that it

allows the guidewire to be retracted into the catheter without losing placement in the

guidewire hole. This technique is often used when the cardiologist is initially inserting

the guidewire and catheter through the hemostasis valve. Retracting the guidewire into

the catheter protects the delicate guidewire tip while advancing across the hemostasis

valve which can damage the tip if exposed.

The distal end of the catheter may be offset from the catheter center line,

improving the removal of thrombus adhering to the vessel wall when the catheter is

rotated around the guidewire. This is an improvement which may be incorporated into a

catheter intended for use in larger vessels. Reinforcing the wall of the catheter with metal or plastic braid substantially increases the torsional strength and kink resistance of

the catheter yet maintains longitudinal flexibility for placement of the catheter within

tortuous vessels.

The suction means may be attached to the catheter with tubing, the size and length of

said tubing being selected to reduce the flow of blood due to friction flow losses,

reducing blood removal from the patient without becoming clogged from aspirated

thrombus particles. This concept was demonstrated, by using a 1/8" i.d. tube, 10 feet

long, connecting the vacuum pump to a catheter, to aspirate 125 cc of blood while

removing a typical thrombus. By reducing the tubing diameter to 1/16" i.d., the amount

of blood aspirated was reduced to approximately 50 cc with no loss of efficacy. There is

an obvious benefit to minimizing the amount of blood lost by the patient.

A valve may be located between the catheter and suction means to shut off or

regulate the vacuum level dehvered to the catheter. This represents a convenient way for the cardiologist to regulate vacuum without having to have someone turn the pump on and off.

The collection bottle may be provided with a window, or clear portion, through

which any clot collected in the filter may be visualized. An access port located above the

clot filter may be provided, through which saline or other washing solutions maybe

directed onto the thrombus to improve visualization and aid in discernment of clot

fragments.

A push-pull transport system as described in U.S. Patent No. 4,561,807,

incorporated herein by reference, may be incorporated into the suction means. The surfaces of all components in blood contact may be coated with an antithrombogenic

material such as heparin complex, hirudin or other clot-inhibiting chemical. The purpose

of such a coating is to ensure that the collected clot came from the treated blood vessel

and was not formed from the liquid blood.

In comparison to some types of therapeutic catheters, such as balloon dilatation

catheters, the percutaneous aspiration catheter has a relatively large cross-section.

This is required to prevent occlusion by the aspirated thrombus. To assist in negotiating

the catheter across restrictions in a blood vessel the distal portion may be coated with a

lubricious or low friction coating such as polyvinylpyrrolidone hydrogel. Use of such a

catheter in the coronary arteries of animal subjects has reduced the difficulty in

penetrating a thrombus. One advantage of using a hydrogel coating for this purpose is

that antithrombotic material such as heparin may be incorporated into the hydrogel

coating, providing both benefits with one coating application. The low friction-coating

may also be placed on the inside of the catheter lumen to reduce the possibility

of the thrombus sticking within it.

The internal flow cross-section of the catheter and connecting tubing may be

provided with a progressively increasing area to the thrombus filter to prevent thrombus

from plugging at any point.

Smooth surfaces and joints may be provided in the catheter and connecting

tubing to prevent thrombus from snagging and catching at any corners or rough edges,

preventing them from reaching the thrombus filter.

The invention can perhaps be better understood by making reference to the drawings,

with reference to Fig. 1, schematic representation of a bifurcated blood vessel 10 is depicted wherein a blunt tip catheter 12 and guidewire 14 are inserted at the point of

bifurcation showing the catheter lodged at the point of bifurcation. Fig. 2 is a

schematic representation of bifurcated blood vessel 10 and an unconstrained angled tip-

catheter 16 and guidewire 14, shown inserted at the point of bifurcation and also

showing the catheter lodged at the point of bifurcation.

With reference to Fig. 3(a), constrained angle tip catheter 18 and guidewire 14

are inserted into bifurcated blood vessel 10. This shows the smooth passage of the

constrained angled tip catheter/guidewire through the point of bifurcation. Fig. 3(b) is a

schematic representation of a bifurcated blood vessel 10 having a constrained angled tip

catheter 18 in an alternative orientation and an inserted constrained guidewire 14 at the

point of bifurcation. Also shown is the smooth transition of the catheter guidewire

through the point of bifurcation.

Fig. 4 comprises a schematic representation of a preferred arrangement of a

complete percutaneous aspiration thrombectomy catheter system according to the present

invention. A constrained angled tip catheter 18 has a guidewire 14 passing through the

constrained distal tip of said catheter guidewire arrangement passing through guide

catheter 20, which in turn is contained within a hemostasis valve 22 through which the

catheter guidewire exits at the proximal end 24. Proximal to the exit of the catheter

guidewire from the hemostasis valve is a guidewire exit port 26. The proximal end of the

catheter is provided with a transitional connecting means 28 which is provided with an

auxiliary Luer port 30. The proximal end of the transitional connecting means is attached

to a connecting tubing 32 which passes through a clamp 34 before entering a collection bottle 36, which is provided with a filter means 38 to separate thrombus from

blood which has been aspirated from a patient's artery. The outlet port of the collection

bottle is provided with additional connecting tubing 40 which passes through a

hydrophobic barrier filter 42 prior to entering the suction end of a suction means 44.

Fig. 5(a) represents a preferred embodiment of a percutaneous aspiration

thrombectomy catheter system according to the present invention, where a two lumen

configuration is depicted showing the catheter 18 having a guidewire 14 passing through

a separate guidewire lumen 42 which is formed as part of the catheter 18. The proximal

end of the catheter passes through a hemostasis valve 22 and subsequently enters a

transitional connection means 28 having an auxiliary Luer port 30, the proximal end of

which connection means 28 is provided with connecting tubing 32.

A cross-sectional of the proximal portion of the catheter 18 is depicted in Fig. 5

(b) showing the internal guidewire lumen 46, which in this section of the catheter is

provided with a slit 48 for easy removal of the guidewire.

The cross-section of the distal portion of the catheter 18 is depicted in Fig. 5(c)

showing the internal guidewire lumen 46, which in this section of the catheter is not

provided with a slit.

Fig. 6(a) is a schematic representation of the tip design for a single lumen

percutaneous aspiration thrombectomy catheter system according to the present

invention, showing the distal end of the catheter 18 having a bent upward distal tip 50

and a thrombus entry opening 52 located in the angled portion of the distal end 54. The

bent up position of the distal tip is provided with a guidewire opening 56 through which

the guidewire 14 passes. In Fig. 6(b) a top plan view of a schematic representation of the distal end of the

catheter 18 shows the angled portion of the distal end 54, the thrombus entry opening

52, and the guidewire entry opening 56.

With reference to. Fig. 6(c) a lateral partly cross-sectional view of the distal-tip of

the catheter 18 of Fig. 6(b) is depicted showing the angle orientation of the angled distal

tip 50 and the location of the guidewire entry opening 56 prior to the formation of the

bent tip in the upward position. The material of catheter 18 is sufficiently flexible that

the distal tip 50 will He flat prior to insertion of guidewire 14. However, if catheter 18 is

made of more rigid material, the distal tip 50 will be bent upward as in Fig. 6 (a), without

guidewire 14 present.

Fig. 6 (d) is an end, distal view of the distal tip according to Fig. 6(c) showing

the catheter 18 and the location of the guidewire entry opening 56 prior to the tip being

bent upward.

With reference to Fig. 7 (a) a cross-sectional representation of a single lumen

catheter 18 is shown which depicts a necked down distal tip 58 and the guidewire 14

passing through the distal end of said necked down distal tip and exiting through the

proximal guidewire exit opening 26.

With reference to Fig. 7 (b) a longitudinal cross-section of the single lumen

design of the percutaneous aspiration thrombectomy catheter system according to the

present invention is shown depicting the catheter 18 the necked down distal tip 58 of the

catheter, and the thrombus entry opening 52. Fig. 7 (c) is a lateral view of the single lumen design of the percutaneous

aspiration thrombectomy catheter system and the necked down distal tip 58, while Fig.

7(d) is a distal end view.

With reference to Fig. 8 a cross-sectional representation of a single lumen off-set

tip design for the percutaneous aspiration thrombectomy catheter system according to

Fig. 5(a) is depicted showing the catheter 18 guidewire 14 thrombus entry hole 52 and

the distal tip having a skewed orientation 60.

The embodiments of the invention shown in Figs. 9(a) to 11(b) represent

variations of the embodiment depicted in Figs. 5(a) to 5(c). In Fig. 9(a) catheter 18

comprises extended guidewire lumen 58, fixed concentric to which is barb 60. Barb 60

has a proximally extending section 62, which has one or more, preferably two, pointed

members 63 to engage thrombus. Pointed members 63 extend slightly into opening 65,

sufficient to be effective to retain thrombus as desired but not to block opening-65.

Another arrangement is shown in Figs. 10(a) to 10(c), where a cutting blade 70 is

positioned on blade holder 72 blade holder 72 is fixedly concentric to extended

guidewire lumen 58. The purpose of blade 70 is to bisect large thrombi that might enter

opening 65.

Barb 60, blade 70, and blade holder 72 are preferably fashioned from rigid

materials. Useful such materials include suitably rigid polymers and co-polymers and

medically acceptable metals.

The embodiment shown in Figs. 11(a) and 11(b) has a dilatation balloon 80

concentrically positioned around catheter 82. Catheter 82 comprises three lumens,

namely, suction lumen 84, guidewire lumen 86, and inflation lumen 88. Balloon 80 is in fluid communication with inflation lumen 88 by means of any conventional

configuration or arrangement, such as one or more inflation port 90.

Manufacture of the catheters herein, including the catheter of Figs. 11(a) and

11 (b), is within the skill of any art skilled person. For example, the balloon can, be

manufactured and/or attached in conventional manner.

Figures 12-14 depict several alternative embodiments of the percutaneous

aspiration catheter. In general, each of these embodiments have barbs which are

mounted inside a catheter near the distal end. Barbs provide the added advantage of

trapping material within the catheter. Barbs also prevent pieces of thrombus from

floating out of the catheter and further provide an apparatus for removing emboli which

are larger than the distal end of the catheter. Variations on these embodiments include

an embodiment with a flared distal end to the catheter (See Fig. 13). The flared distal

end has the advantage of providing a larger diameter capture opening. The flared distal end also allows room for the placement of barbs within the tip without restricting the

removal of particles. Any particles that are small enough to pass through the catheter

lumen will not be impeded by the barbs.

Another embodiment has an angled tip, where the angled tip provides a less

traumatic tip and also creates a larger cross-sectional area to the distal opening of the

catheter (See Fig.s 12a and 14a). Another embodiment is disclosed that may be used

over a guide wire (See Fig.s 12a and 14a). Finally, an embodiment with a fixed guide

wire tip at the distal end of the catheter is disclosed (See Fig. 13). The fixed guide wire

tip provides some of the advantages of a guide wire while also providing a maximum

cross-sectional open lumen for thrombus removal. It is possible to make any of these embodiments in a fixed wire, over the wire, or no wire configuration. Further, any of

these embodiments may have a straight tip, an angled tip, or a flared tip. All materials,

dimensions, processes of manufacture, features, and advantages previously described

may also apply to the following embodiments except as described hereafter.

Figure 12a depicts an embodiment of the percutaneous aspiration catheter where

barbs 110 are positioned within the distal portion of catheter 18 and oriented such that

the sharp part of the barb 110 is pointed proximally. Barbs 110 may be made separately

and attached to the interior of catheter 18 or integrally formed in a ring 115. Barbs 110

may be machined into ring 115 by milling or laser cutting and are preferably formed by

electrical-discharge machining. It is very important that barbs 110 be as sharp as

possible. Therefore post polishing or sharpening of barbs 110 may be preferred after

barbs 110 are machined into ring 115. Ring 115 may further be bent into a noncircular

shape, as shown in Figure 12b, where a reverse bend 118 in the circumference of ring 115 may act as a guide wire retainer. Reverse bend 118 retains guide wire 14 near the

edge of the interior of catheter 18 and therefore provides the maximum continuous cross-

sectional area for thrombus to travel through catheter 18.

Ring 115 may be made of any medical grade metal, and is preferably a radio-

opaque alloy, such as a platinum-iridium alloy consisting of 90% platinum and 10%

iridium. As a radio opaque alloy, ring 115 may also serve as a marker band facilitating

radiographic visualization. Ring 115 may be mounted near the distal opening of catheter

18. Preferably ring 115 is adhesively bonded to the interior of catheter 18. Adhesives

that may be used include cyanoacrylates and epoxies. Catheter 18 may be used with a guide wire 14, without a guide wire, or in a fixed

wire configuration. Catheter 18 may have a single layer or plurality of layers. In a

preferred embodiment catheter 18 may be made from three layers where the inner layer is

made of PTFE and has a wall thickness of about .003 inches. The intermediate layer is a

braid of metal or plastic filaments with a wall thickness of about .002 inches. The braid

may have a continuous or variable pick count. The outer layer is a thermoplastic such as

polyurethane with a wall thickness of about .002 inches. When using catheters 18 with

as larger as an outside diameter of .039 inches, the flared tip may be as large as .052

inches allowing barbs 110 to be bent inward .0065 inches without restricting the size of

particles that may be drawn into catheter 18.

Figure 13 shows another embodiment of the percutaneous aspiration catheter where the distal end of catheter 18 is larger in diameter than the body of catheter 18.

This flared portion 125 provides a larger working area for the suction end of catheter 18. Flared portion 125 preferably is formed by stretching the distal portion of catheter 18

over a hot mandrel. However, in embodiments where a layer of braid is incorporated

into the construction of catheter 18, a separate flared portion 125 may be constructed and

adhesively attached to the distal end of catheter 18.

Figure 13 also shows a fixed guide wire tip 120 which is mounted inside the

distal end of catheter 18 and extends out of the distal end. Guide wire tip 120 has a

spring tip 14, as is commonly known in the art. Guide wire tip 120 may fit into a reverse

bend 118 as in the embodiment shown in Figure 12b. Guide wire 120 is adhesively

bonded to catheter 18. Guide wire tip 120 provides guidance for catheter 18 and is

helpful in negotiating the tortuous vasculature. Since guide wire tip 18 is bonded to catheter 18 near the distal end but does not extend proximally of the bond, guide wire tip

18 does not block most of the fluid path within catheter 18. This guide wire tip

configuration provides the ability to negotiate tortuous vessels and still have the high

suction capability of embodiments of the percutaneous aspiration catheter that do not

have a wire.

Both of the embodiments of Figures 12a and 13 show an angled distal end of

catheter 18 where the guide wire 14 or the fixed guide wire tip 120 is preferably

positioned to correspond to the distal-most portion of the angled end of catheter 18. As

previously described, an angled tip provides better advancement around corners and

through bifurcated vessels. Figure 12a depicts the distal opening of catheter 18 having

an angle θ with respect to a line parallel to the axis of catheter 18. The distal opening

therefore must also be oriented at an angle θ with respect to the axis of catheter 18 and

must be from 0-90°. Figure 14a shows yet another embodiment of the percutaneous

aspiration catheter where the distal end of catheter 18 is flat and Figure 14b depicts a

side view of the embodiment of Figure 14a.

In use, barbed embodiments of the percutaneous aspiration catheter have several

added benefits. During normal aspiration barbs 110 provide a safety mechanism where

embolus that is drawn into catheter 18 can not float out of the end of catheter 18. In

addition, barbs 110 may be particularly useful in removing particles which are larger

than the diameter of catheter 18. In cases like these a portion of a large piece of

thrombus may be drawn into the end of catheter 18 and caught by barbs 110. Even

though the piece of thrombi is too large to flow through catheter 18 it can then be

removed from the body by removing catheter 18. It will be further apparent to one skilled in this art that the improvements

provided for in the present invention, while described with relation to certain specific

physical embodiments also lend themselves to being applied in other physical

arrangements not specifically provided for herein, which are nonetheless within the spirit

and scope of the invention taught here.

Claims

I claim:

1. A percutaneous aspiration catheter comprising:

a catheter having a proximal end, a distal end, and a lumen therethrough;

and

a plurality of barbs mounted within the distal end of the catheter lumen.

2. The percutaneous aspiration catheter of claim 1 wherein the barbs are integrally

formed with a ring, the ring mounted within the lumen of the catheter near the distal

end.

3. The percutaneous aspiration catheter of claim 2 wherein the ring is made of a radio

opaque material.

4. The percutaneous aspiration catheter of claim 2 wherein the ring describes a

substantially circular shape with a reverse bend suitable for forming a channel to act

as a guide wire retainer.

5. The percutaneous aspiration catheter system of claim 1 wherein portions of the

catheter are coated with an anti-thrombogenic coating.

6. The percutaneous aspiration catheter system of claim 1 wherein the distal end of the

catheter is coated with a lubricious coating.

7. The percutaneous aspiration catheter of claim 1 further comprising:

a guide wire lumen within the catheter lumen.

8. The percutaneous aspiration catheter system of claim 7 wherein a proximal end of the

guide wire lumen is provided with a slit for a portion of the length of the guide wire

lumen from a proximal end of the guide wire lumen toward a distal end of the guide

wire lumen, the slit allowing for the peeling of the catheter from a guide wire therein.

9. The percutaneous aspiration catheter of claim 1 further comprising:

a wire tip attached to an internal surface of the catheter lumen and

extending beyond the distal end of the catheter.

10. A percutaneous aspiration catheter which comprises:

an elongate tube having a lumen therethrough;

a plurality of barbs positioned within a distal end of the lumen;

a first proximal lumen diameter;

a second distal lumen diameter; and

a transition zone between the first diameter and the second diameter.

11. The percutaneous aspiration catheter system of claim 10 wherein the second diameter

is greater than the first diameter.

12. A percutaneous aspiration catheter which comprises:

an elongate catheter having a lumen therethrough;

a plurality of barbs positioned within a distal end of the lumen; and

a distal opening, the opening located at the distal end of the catheter and

oriented at an angle of less than 90┬░ with respect to an axis of the catheter lumen.

13. An embolectomy method comprising:

providing a catheter having an elongate body, a lumen therethrough, a

distal opening, and barbs mounted within the lumen near the distal opening;

advancing the catheter through the vasculature until the distal opening is

adjacent a site to be treated; and

providing suction at a proximal opening of the catheter.

14. The embolectomy method of claim 13 further comprising;

catching material larger than the diameter of the lumen in the barbs; and

removing the catheter from the vasculature while the material remains

caught in the barbs.