WO1989000835A1

WO1989000835A1 - Catheter with rotatable annular cutter

Info

Publication number: WO1989000835A1
Application number: PCT/US1988/001661
Authority: WO
Inventors: Royce H. Husted
Original assignee: Husted Royce Hill
Priority date: 1987-07-27
Filing date: 1988-05-17
Publication date: 1989-02-09

Abstract

A catheter (10) for opening obstructions in human blood vessels and the like comprising a flexible tube (13) equipped with a hollow annular cutter (16) rotatably mounted at its first end and driven by a motor (26) through an off-center flexible wire (20) and a suction pump (25) at its other end for extracting the obstructions severed by the annular cutter. A flexible catheter (110) for use in very small blood vessels is also disclosed comprising a coil spring (114) rotatably mounted in the end of a hollow tube (112). The spring is driven off center by a flexible wire drive shaft (134) that is an extension of the coil spring. The end turn of the coil spring forms a cutting edge. A thin, flexible wire guide (116) is affixed to the outside of the hollow tube adjacent to the coil spring and extends in front of the cutting edge. The wire guide has a free end that passes back into the coil spring and hollow tube. The wire guide follows the orientation of the blood vessel and guides the coil spring.

Description

CATHETER WITH ROTATABLE ANNULAR CUTTER

The present invention is- directed to improvements in a catheter, and more particularly, to an improved catheter provided with a rotatable annular cutter and a method of using same for clearing obstruction in blood vessels, such as human arteries. With age a large portion of the population develops arterial obstructions formed by fats, fibrous material and calcified deposits, resulting in diminished blood supply to the heart, brain and other organs. Presently such obstructions are circumvented surgically by providing a bypass or they are treated with a cath¬ eter equipped with a balloon which is inserted into the obstruction area through the arterial system and then inflated to expand the lumen through the obstuc- tion. A problem with the balloon catheter is that it may burst th.e artery and in certain cases- it is in¬ effective. Further, it does not remove the obstruction material out of the arterial system.

One aim of the present invention is to provide an improved catheter having a rotatable annular cutter, and more specifically, is directed to a catheter for clearing arterial obstructions including flexible tube means adapted to be inserted into an artery ad¬ jacent to an obstruction, substantially hollow cutter means comprising a thin-walled annular cutter having a cutting edge at its forward end for rotatably slicing into said obstruction, bearing means for sup¬ porting said annular cutter in axial alignment with and at least partially within the forward end of said flexible tube means, thin flexible wire means attached to the wall of said annular cutter for im¬ parting an off-center rotational drive force to said annular cutter and providing a substantially obstruction-free passageway through said annular cutter and drive means for rotating said flexible wire means.

The present invention is further directed A to a method for clearing an obstruction in an artery comprising the steps of inserting into an artery a flexible tubular catheter having a hollow cutter rotatably supported therein, positioning the tubular catheter with, the hollow cutter adjacent to and in contact with, an obstruction, rotating the hollow cutter by means of an o f-center flexible shaft affixed to a wall of the hollow cutter to provide a substan¬ tially obstruction free passageway into the tubular catheter for reception of cut material, applying negative pressure to the other end of the tubular catheter to suck cut material into the catheter, and removing the catheter and its contents from the arter .

When dealing with large blood vessels, such as the femoral artery, relatively rigid catheter structures may b utilized with some degree of suc- cess. However, when dealing with very small blood vessels or with vessels that include relatively sharp bends, or turns, the catheter must be extremely flexible. In general, a thin guide wire is positioned by the surgeon next to an obstruction in a. blood vessel and a catheter tube introduced over the guide wire. The guide wire may he removed before commencing blockage opening procedures. Various well-known f uoroscopy techniques may be utilized .for assisting the position¬ ing of the guide wire, the guiding of the catheter to the site of the obstruction and the operation of the obstruction opening device.

In accordance with, a further aspect of the invention, the cutter tip itself is flexible to permit it to follow the orientation of the obstructed vessel and to negotiate relatively sharp turns therein.

The present invention therefore also provides a catheter for opening obstructions in blood vessels including a thin, flexible, cylindrical tube adapted for insertion in a vessel adjacent to an obstruction, an annular cutter positioned at one end of said cylindrical tube and adapted for rotation therein^ said annular cutter having a flexible coil spring body and terminating in a cutting edge, and wire means for imparting an off center rotational driving force to said body.

Another aspect of the invention is to provide a self-guiding catheter which preferably, more readily conforms to bends and turns in blood vessels.

One feature of the invention is that catheters, made in accordance with the invention are much, safer in use. Another feature of the invention is its unitary design of flexible off center drive shaft, flexible cutter body and cutting edge.

Further features and advantages of the in¬ vention will be apparent upon reading the following description of preferred embodiments of the invention in conjunction with, the drawings, in which:

Fig. 1 shows a general cross sectional view of an embodiment of the invention;

Fig. 2 shows a cross sectional view of the embodiment along a line 2-2 marked on Fig. 1; Fig. 3 shows ^"across sectional view of the embodiment along a line 3-3- marked on Fig. 1;

Fig. 4 is a simplified representation of a catheter constructed in accordance with a further em¬ bodiment of the invention; Fig, 5 is an enlarged view of the unitary flexible cutter and guide wire of the catheter of Fig. 4; Fig. 6 is an enlarged cutaway portion of a unitary flexible cutter and guide wire constructed in accordance with another form of the invention; and

Fig. 7 is a partial cutaway section depicting use of the catheter of Fig. 6 to remove obstructions in a curved portion of a blood vessel.

Figures 1 - 3 show a catheter 10 insertable into a patient's artery 11 for remotely cutting and removing an obstruction 12 therein, comprising: a flexible-tube 13 having a first opening 14 and a second opening 15. An annular cutter or tubular-blade 16 has a groove 17 which rides on a lip 18 of a hollow bearing 19. The hollow bearing 19 is attached to the first opening 14 and rotatably supports the tubular- blade 16.

A flexible-shaft 20, made preferably of a steel wire, having first end 21 and a second end 22, is rotatably disposed in the flexible-tube 13.

The first end 21 is coupled to the tubular- blade 16, preferably, by being inserted and affixed in a small hole 23 which is drilled in the tubular- blade's wall. .This offset drive leaves the tubular blade's center open for .freely accepting obstruction material, and as the material enters- the flexible- tube 13 it is continuously agitated and broken down to pieces, by the rotating flexible-shaft 20.

A motor (air or electric). 26 is coupled to the second end 22 for rotating the tubular-blade 16 through, the flexible-shaft 20. Suction means 25 for generating negative pressure is connected to the second opening 15, for pulling the obstruction material into and through the flexible-tube 13. The agitating action of the flexible- shaft 20 prevents the obstruction material from forming a solid obstruction in the flexible tube 13 and assists suction means in moving the obstruction material through the flexible-tube 13.

A manifold 27 is attached to the motor 26, to the flexible tube 13 and to the suction means 25. The manifold contains an 0-ring seal 28 which seals around the flexible-shaft 20.

The process for removing an obstruction 12 from an artery 11, comprises the following steps:

Inserting into the artery 11 a first opening 14 of a catheter 10 as shown in Fig. 1, and bringing the tubular-blade 16 into contact with the obstruction 12, rotating the tubular-blade 16 by means of the flexible shaft 20- and cutting the obstruction 12 while applying negative pressure to a second opening 15 of the cath¬ eter 10 to suck obstruction material into the catheter 10, and removing the catheter 10 and its contents from the artery 11.

Figures 4 - 7 display further embodiments of the invention that are especially designed for op¬ erations in very small blood vessels or vessels that include relatively sharp bends or turns.

Referring to Fig. 4, a catheter generally designated by reference numeral 110 includes a small diameter inner flexible tube 112 terminating in a novel hollow flexible coil spring cutter 114 and a fine guide wire 116. Hollow cutter 114 is rotatably driven by a thin, flexible wire drive shaft 134 that extends the length, of tube 112 and is coupled to a motor 118. Hollow cutter 114 is driven in an off center manner by drive shaft 134 in identical fashion to the offset drive of tubular blade 16 in Figures 1 - 3. A source of vacuum 120 is connected to one end of tube 112 to assist cut material (.not shown) being drawn into the other end of catheter 112 through, hollow cutter 114. In one modification of this aspect of the invention, a similarly configured outer hollow tube 122, substantially coextensive with tube 112, may be used in conjunction with, a pump 124 for injecting a saline solution or the like through the annular space between concentric tubes 122 and 112 to the site of the ob¬ struction adjacent cutter 114. The end of the outer hollow tube 122 may also serve as a bushing, as at 5 122a, which holds flexible coil spring cutter 114 in axial confinement. Guide wire 116 is very thin and flexible and is used by the surgeon to guide the catheter through a blood vessel and to the site of the obstruction that is to be opened or removed. A rounded 0 end 116a helps guide wire 116 to follow the path of the blood vessel. It will be appreciated that the motor, pump and vacuum source, enclosed by dashed line box 121 are schematically illustrated only. A slot 123, in outer tube 122, enables tube 122 to be axially 5 moved relative to tube 112, as will be explained.

In Fig. 5, tube 122 is shown in its forward- most position, as- it would be while inserting and guiding the catheter into position adjacent to an obstruction. When tube 122 is axially moved to the

20 forward Insertion position, it completely covers cutter 114, and when it is retracted to the Operation position, it is pulled back relative to tube 112 to expose a substantial portion of flexible cutter 114. Slot 123 in tube 122 permits movement between the

25 Insertion and Operation positions without disturbing guide wire 116.

The end portion of tube 112 may have a thinner wall to promote flexibility and may have a slightly greater diameter than the diameter of coil

30. spring cutter 14. This provides a shoulder 112a for the cutter to bear against during its rotation. End 115 of guide wire 116 is embedded in the wall of tube 112 and rigidly secured thereto. This configura¬ tion is preferred when two concentric tubes are de-

35 sired or needed for the catheter.

In Fig. 6, another embodiment using the novel flexible cutter 114 is disclosed. Tube 112 is seen to have a larger diameter cross section near its end 113 forming a lip or shoulder 112b. The inner surface of end 113 in this embodiment provides a bearing for cutter 114 to rotate in, generally in the 5 direction of the circular arrow A. Guide wire 116 is formed of a fine piano wire or the like and includes a sharp bend to form a rounded tip 116a and has one end 115 securely embedded in the wall of tube 112 by any suitable means, such as by gluing, and its other

2_0_. end.117 extends freely through the central opening of coil spring cutter 114 and terminates inside tube 112. The outer end turn 130 of coil spring cutter 14 is preferably shaped to form a cutting edge 114a and the end turn 131 adjacent shoulder 112b is bent

15 at 132 substantially a right angle, and extends paral¬ lel to the axis of the cutter 114 through, the length of tube 112, where it is coupled to drive motor 118 via drive shaft 134. This embodiment of the invention does not use an outer tube and inner shoulder 112b in

2o. e d 113 functions as a type of thrust bearing to help rotatably confine flexible cutter 114. This par¬ ticular construction should not be considered limiting of the invention, however. Bend 132 should be made in such a way so as to maintain a substantially open

25 passageway through hollow cutter 114 for ingress of cut material. It will also be apparent that the cutting edge 14a on end turn 130 of the coil spring cutter may be formed in any of a variety of ways, including having the taper oppositely extending to that

30. shown so that an outward flare is imparted to the open end of cutter 114. As indicated, the direction of ro¬ tation (arrow A) _of cutter 114 is such that end turn 130 tends to remain closely coupled to its adjacent coil spring turn. It will also be appreciated that,

35 rather than using the end turn of the coil spring as the cutting edge, a separate annular cutting element may be affixed to the end turn of the spring by any suitable means. It is also contemplated that end turn 130 may be flattened to present a cross section that is more readily adapted and shaped into a cutting edge. Any of such constructions would not materially 5 affect the flexibility of the body of cutter 114, which, is a key aspect of the invention.

I;t will, of course, be apparent to those skilled in the art that the preferred one-piece, off center drive shaft and open, flexible cutter design 0 lends itself to extreme miniaturization. Since even a 20% opening in a blocked vessel may provide suf¬ ficient blood flow, this miniaturization capability makes the inventive design very attractive.

In Fig. 7, the flexible coil spring cutter 5 114, tube 112 and guide wire 116 of Fig. 6 are shown in position in a blood vessel 140 that has a partial obstruction or blockage 142. Guide wire 116 and rounded tip 116a enable the tube 112 to follow the bends of the blood vessel 140 and to be positioned

20 with, end turn 114a of cutter 114 adjacent to the ob¬ struction 142. As mentioned, guide wire 116 is very flexible and readily conforms to the bends and turns in the blood vessel 140. As the guide wire 116 bends, it forces flexible cutter 114 to follow. Also

25 as mentioned, the surgeon constantly monitors- the position and orientation of the catheter via a fluoro- scope or the like while it is being inserted and adjusts its orientation to keep the outside portion of guide wire 116 adjacent to the large radius side of a

30. turn in the vessel. Throughout its insertion and operation, cutter 114 is confined by guide wire 116 which, precludes the possibility of inadvertently punc¬ turing or cutting through the wall of vessel 140. As cutter 114 is rotated, via the off center rotational

35 drive force applied through drive shaft 134, free end 117 of guide wire 116 will be nudged out of the way every revolution since guide wrie 116 does not rotate. Those skilled in the art will readily recog¬ nize that the cutter 114 need not be confined within the end of tube 112. Rather, operation of the coil spring cutter of the invention completely outside of the catheter tube is envisioned, especially when used with a guide wire, and when so configured, the vessel itself serves as the annular confinement for the rotary coil spring cutter.

Claims

1. A catheter for clearing arterial ob¬ structions including flexible tube means adapted to be inserted into an artery adjacent to an obstruction, substantially hollow cutter means comprising a thin- walled annular cutter having a cutting edge at its forward end for rotatably slicing into said obstruction, bearing means for supporting said annular cutter in axial alignment with and at least partially within the forward end of said flexible tube means, thin flexible wire means attached to the wall of said annular cutter for imparting an off-center rotational drive force to said annular cutter and providing a substantially obstruction-free passageway through- said annular cutter and drive means for ro¬ tating said flexible wire means.

2. The catheter of claim 1, wherein said cutting edge tapers inwardly for guiding cut material from said obstruction toward the interior of said

• thin cylinder.

3. The catheter of claim 1 or 2, including means for applying a negative pressure to said flexible tube means for assisting entry of cut material therein.

4= The catheter of claim 1, 2 or 3 wherein said annular cutter includes a hole in its wall for attachment of said wire means to said annular cutter, said hole extending substantially parallel to the axis of said flexible tube means.

5. A catheter for opening obstructions in blood vessels including a thin, flexible, cylindrical tube adapted for insertion in a vessel adjacent to an obstruction, an annular cutter positioned at one end of said cylindrical tube and adapted for rotation therein, said annular cutter having a flexible coil spring body and terminating in a cutting edge, and wire means, for imparting an off center rotational driving force to said body.

6. The catheter of claim 5 wherein said coil spring body has an end turn that forms said cut¬ ting edge.

7. The catheter of claim 5 or 6 wherein said wire means comprise an extension of the other end of said coil spring body.

8. The catheter of crlaim 5 or 6 including guide means extending forwardly of said cutting edge for guiding and bending the flexible coil spring body of said annular cutter to follow the orientation of said vessel.

9. The catheter of claim 8 wherein said guide means comprise a loop of thin wire extending outside said coil spring body and having one end fixed to said cylindrical tube and the other end freely extending through said annular cutter.

10. The catheter of claim 5 or 6 wherein said annular cutter is positioned at least partially within said one end of said cylindrical tube.

11. The catheter of claim 10, including means for providing suction at the end of said cylin¬ drical tube for assisting entry of material cut from said obstruction into said annular cutter and cylindri¬ cal tub .

12. The catheter of claim 11, including a concentric outer flexible cylindrical tube that is movable axially to cover and expose said cutting edge.

13. A catheter for use in clearing an obstruc- ^' tion in a blood vessel including a thin, flexible, hollow tube adapted to be positioned in a vessel with one end adjacent to an obstruction therein, a hollow coil spring rotatably movable in said one end of said hollo tube and having an annular cutting edge ex¬ tending outside said one end of said hollow tube, a thin, flexible wire extension of said coil spring extending within said tube for imparting a rotational drive force to said coil spring, and a thin, flexible wire guide extending forwardly of said cutter for fol¬ lowing the course of said vessel and for forcing said coil spring to deflect in the direction of said course.

14. The catheter of claim 13 wherein said wire guide has one end affixed to the outside of said hollow tube and a free end extending into said coil spring.

15: The catheter of claim 13, including a concentric outer flexible cylindrical tube that is movable axially to cover and expose said cutting edge.

16. The catheter of claim 13, 14 or 15, including means for providing suction at the end of said hollow tube for assisting movement of material cut from said obstruction into said coil spring and said hollow tube.

17.. A method for clearing an obstruction in an artery comprising the steps of inserting into an artery a flexible tubular catheter having a hollow cutter rotatably supported therein, positioning the tubular catheter with the hollow cutter adjacent to and in contact wth an .obstruction, rotating the hol¬ low cutter by means of an off-center flexible shaft affixed to a wall of the hollow cutter to provide a substantially obstruction free passageway into the tubular catheter for reception of cut material, applying negative pressure to the other end of the tubular catheter to suck out material into the cath¬ eter, and removing the catheter and its contents from the artery.