WO1989005611A1

WO1989005611A1 - Atherectomy device with angioplasty balloon and method

Info

Publication number: WO1989005611A1
Application number: PCT/US1988/004419
Authority: WO
Inventors: Richard L. Mueller
Original assignee: Devices For Vascular Intervention, Inc.
Priority date: 1987-12-14
Filing date: 1988-12-09
Publication date: 1989-06-29
Also published as: AU2829189A

Abstract

An atherectomy device (1) for reducing stenosis material from a vascular vessel is provided. The atherectomy device includes an elongated flexible tubular member (8) having at least one lumen extending therethrough and having proximal and distal extremities. A flexible drive means (9) disposed within the tubular member is free to move both rotationally and axially therein. A cutting assembly (5) is carried by the distal extremity of the flexible tubular member (8) with a cutter (57) being carried by the distal extremity of the flexible drive means (9) for removing a portion of the stenosis from the vessel wall. An inflatable dilation balloon (7) is carried by the tubular member (8) proximally of the cutter (57) for further reducing the stenosis after initial reduction by the cutter (57).

Description

ATHERECTOMY DEVICE WITH ANGIOPLASTY BALLOON AND METHOD

The present invention relates generally to an atherectomy device and method for reducing stenosis within vascular vessels.

Coronary and peripheral vascular arteriosclerosis, known also as atherosclerosis, is a common ailment occurring in humans which involves deposition of fatty-like substances called atheroma or plague on the walls of blood vessels. These plague deposits are most common in the peripheral blood vessels that feed the limbs of the human body and the coronary arteries which feed the heart. When long term plague build-up reaches the point of nearly totally occluding a vessel, a thrombus (clot) type attachment can occur resulting in a long segment of soft vessel occlusion. Occasionally these fatty deposits occur in fairly localized regions of a blood vessel, thereby restricting the blood's flow and imposing a serious risk to the person's health.

In the past, several methods have been attempted to restore normal blood flow through the affected vessels. Traditionally, major surgery was the only practical means for treating occlusions. More recently, there has been substantial success in increasing the size of the flow passage within occluded vessels through the use of a dilation process known as balloon angioplasty. However, in a substantial percentage of the cases where balloon angioplasty is used, the removed plague deposits will reoccur. More recently, there has been an interest in atherectomy devices that actually cut through stenosis within a vessel regardless of whether the stenosis is primarily a plague type deposit or a thrombus type clot. For example, U.S. Patent No. 4,669,469 discloses a side cutting atherectomy device for removing material from an atheroma in the vascular system. Similarly, co-pending applications serial numbers 045,916 filed May 1, 1987 and 117,072 filed November 5, 1987, which are in¬ corporated herein by reference, disclose alternative designs for end cutting atherectomy devices.

A drawback of such atherectomy devices is that they often leave rough edges when cutting. Additionally, since the cutter size is restricted, it is not always possible to open a passage as large as desired when using such devices. Further, such devices are not capable of securely anchoring the atherectomy device in place while cutting proceeds.

Therefore, it is a primary objective of the present inven¬ tion to provide an atherectomy device that is particularly well suited for reducing stenosis materials that occlude a blood vessel.

Another objective of the invention is to provide an atherectomy device with an inflatable member that may be used to smooth the sides of an expanded passage cut through a stenosis within a vessel.

Another object of the invention is to provide an atherectomy device capable of dilating a vessel to further reduce a stenosis after some cutting has occurred.

Another objective of the invention is to provide a means for setting an atherectomy device while cutting occurs.

To achieve the foregoing and other objects and in accordance with the purpose of the present invention, an atherectomy catheter for removing at least a portion of a stenosis within a vessel is provided having a cutting assembly and an inflatable member. The atherectomy catheter includes an elongated flexible tubular member having at least one lumen extending therethrough. A flexible drive means is disposed within the tubular member and is mounted for axial and rotational movement therein. A cutter is carried by the distal extremity of the flexible drive means. The inflatable member, which may take the form of a dilation balloon, is carried by the tubular member proxi ally of the cutter with the interior of the inflatable member being in communication with a lumen in the flexible tubular member.

The atherectomy catheter also preferably includes flexible guiding means extending forward of the cutter for guiding the cutter to travel axially within the vessel and collection^' means for collecting the removed stenosis materials. Additionally, inflation means is provided for inflating and deflating the inflatable member. Preferably the cutter and flexible drive means are movable axially relative to the tubular member.

The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiment, taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a diagrammatic side elevational view of a catheter constructed in accordance with the present invention.

FIGURE 2 is a cross-sectional view taken along line 2-2 of Figure 1 highlighting a possible construction for an elongated tubular member suitable for use with the device shown in Figure 1. - - FIGURE 3 is a diagrammatic side view of an alternative cutting assembly incorporating the present invention.

FIGURE 4 is a diagrammatic side view of another cutting assembly that incorporates the present invention.

^" FIGURE 5 is a cross-sectional view taken along line 5-5 of Figure 3 which highlights a tubular member construction suitable for securing the angioplasty balloon.

As shown in the drawings, an illustrative embodiment of the atherectomy catheter 1 of the present invention includes a proximal actuator assembly 3, a cutter assembly 5, an inflatable member 7 and a tubular member 8 that connects proximal actuator assembly 3 to cutter assembly 5. A flexible drive means 9 is disposed within tubular member 8 and is adapted for rotational and axial movement therein. The cutter assembly 5 is carried by the distal extremity of tubular member 8. The inflatable member 7 may take the form of a dilation balloon and is carried by tubular member 8 proximally of cutter assembly 5.

In one embodiment of the present invention, as shown in Figure 1, the cutter assembly 5 is constructed substantially identically with cutter assembly described in co-pending application serial number 732,691 filed May 10, 1985. Specifically, a housing 55 protects a cutter 57 carried therein and is mounted on the distal extremity of the flexible tubular member 8 and an inflatable member in the form of atherectomy balloon 40 is provided to position the housing 55 and cutter 57 relative to a stenosis disposed on one side of the atherectomy catheter 1.

The proximal actuator assembly 3 includes a coupling member 13, an angioplasty port 15, a three arm adapter 17 threadably connected to a thumb screw 19 and a drive shaft 21.

Coupling member 13 is secured to tubular member 8 by any suitable means such as gluing. Angioplasty port 15 is threadably secure between coupling member 13 and three arm adapter 17, and has an arm 18 attached to valve 25. Three arm adapter 17 itself includes a flush port 27 and an atherectomy port 28. Atherectomy port 28 is also attached to the valve 25.

The valve 25 includes a fluid access port 26 for receiving fluids and a switch mechanism for directing the fluid flow to either angioplasty port 15 or atherectomy port 28. Access port

26 is connected to a fluid source (not shown) which provides saline solution that may be used to inflate the inflatable members 7 and 40. Since it is contemplated that only one of the two inflatable members (dilation balloon 7, atherectomy balloon 40) will be inflated or deflated at a time, the switch¬ ing mechanism facilitates selective communication between the fluid source and the two inflatable members 7, 40. Thumb screw 19 is threadably coupled to the third arm of three arm adapter 17 while O-ring seal 31 prevents fluid from leaking from the atherectomy catheter 1. Drive means 9 which takes the form of a braided drive cable is anchored in drive tube 33 which forms an extension of drive shaft 21. Drive tube 33 passes coaxially through thumb screw 19 and is firmly adhered to drive shaft 21.

It will be appreciated that the drive cable 9 can be moved rotationally relative to tubular member 8 by rotating drive shaft 21. Additionally, drive cable 9 can be moved axially relative to tubular member 8 by pushing thumb lever 35 toward thumb screw 19 against the pressure of spring 37 which is placed about drive tube 33 between thumb screw 19 and drive shaft 21. When tension is released from thumb lever 35, compression spring 37 will cause thumb lever 35 and thumb screw 25 to separate thereby causing drive cable 9 and hence cutter 57 to move axially relative to housing 55. The cutter 57 works best when rotated at a high rate of speed. Therefore, drive shaft 21 on proximal assembly 3 is preferably εplined and adapted to be coupled to a motorized drive unit (not shown) . A suitable motorized drive unit is disclosed in co-pending application serial number 031,168 filed March 26, 1987. A suitable rotational speed for the cutter 57 is approximately

2500 RPM. A guide wire 69 may extend coaxially through a lumen in drive cable 9 and drive shaft 21 and may be free to move longitudinally therethrough to facilitate introduction of the cathete .

Tubular member 8 is formed of a three-lumen core tubing as seen in Figure 2. The outer portion of tubular member 8 may be formed in any conventional manner. By way of example, the tubular member 8 may be formed of a braided torgue transmitting layer 81 encased by a shrink fit jacket 82. The torgue transmitting layer 81 carries an angioplasty lumen 50 and an atherectomy lumen 52 in addition to drive cable 9. To inflate dilation balloon 7, valve 25 is actuated such that access port 26 communicates with an arm 18 of angioplasty port 15. The angioplasty lumen 50 includes an input aperture 43 that facili¬ tates fluid communication between angioplasty port 15 and the interior of angioplasty lumen 50. Leak proof seal 45 seals the connection between angioplasty port 15 and coupling member 13 while seal 47 prevents fluid from leaking between angioplasty port 15 and the three arm adapter 17.

When the atherectomy balloon 40 is to be inflated or deflated, valve 25 is switched such that access port 26 is in fluid communication with atherectomy lumen 52.

In the embodiment shown in Figure 1, the cutter assembly includes a housing 55 mounted at the distal extremity of the flexible tubular member 8 and can be formed of suitable mate¬ rials such as stainless steel. It is generally cylindrical as shown and has its proximal extremity secured to housing tail piece 54 as shown in Figure 2. A cutout 56 is provided in the housing 55 in one side thereof and faces in a direction which is generally perpendicular to the longitudinal axis of the housing 55. A work performing device in the form of a cutter 57 is slidably mounted within the housing 55 and is provided with a circular cutting edge 58 which lies in the plane perpendicular to the longitudinal axis of the housing in the axis of longitudinal movement of the cutter 57. A bell-shaped recess 59 provided within the cutter 57 and extends rearwardly from the cutting edge 58.

Atherectomy balloon 40 is attached to atherectomy lumen 52 by any conventional means such as an adhesive. Atherectomy balloon 40 passes through an aperture 60 in housing tail piece 54. The proximal extremity of the atherectomy balloon 40 is connected in a suitable manner with the atherectomy lumen 52 in the flexible tubular member 8 so that the balloon can be inflated and deflated as desired. The distal extremity balloon of 40 is tied to nose cone 62 in a conventional manner. By way of example, a suitable tie-off technigue is to wrap a suitable means such as nylon wire 64 into a recess 66 provided in the nose piece 62. The nose cone 62 is secured to the open distal end of housing 55 by suitable means such as an adhesive. The nose cone 62 is provided with a rounded forwardly extending surface 67.

A conventional flexible elongated guide wire 69 provided with a helical coil spring at its distal extremity is removably mounted in the atherectomy device. The guide wire 69 extends through the hollow flexible drive cable 9, through a bore in cutter 57, the housing 55 and through a bore provided in nose cone 62. The guide wire 69 serves as a guiding element for inserting the catheter into a vessel in the vascular system of a patient.

The inflatable dilation balloon 7 is attached to tubular member 8 directly behind cutter assembly 5. Preferably the dilation balloon 7 is mounted coaxially with tubular member 8 and conventional P.E.T., P.V.C., or polyolefin family dilation balloons may be used.

To secure dilation balloon 7 in place, shrink fit jacket 82 will terminate before the junction with housing tail piece 54 and will be used to hold the proximal end 86 of dilation balloon 7 as shown in Figure 3. Specifically, the proximal extremity of dilation balloon 7 is glued to torgue transmitting layer 81 and heat-shrinkable tubing is adhered in place over the proximal extremity and heat treated to shrink wrap the proximal end 86 of dilation balloon 7, thereby firmly securing it into place. The distal extremity of dilation balloon 7 may be adhered to housing tail piece 54. Additionally, a nylon wire 88 may be wrapped into a recess 89 in housing tail piece 54, thereby firmly securing the dilation balloon 7 to the atherectomy catheter.

Fluid communication between the fluid source (not shown) and dilation balloon 7 is accomplished through valve 25, angioplasty port 15 and angioplasty lumen 50. An aperture 90 in tubular member 8 allows fluid to communicate directly between the interior of dilation balloon 7 and angioplasty lumen 50. The proximal extremity of angioplasty lumen 50 may be blocked to prevent leakage into the interior of tubular member 8. The plugs may be formed of an extruded bead or a suitable adhesive.

An alternative embodiment of the present invention in shown in Figure 4. In this embodiment a cutting assembly as described in co-pending application serial number 045,916 filed May 1, 1987 is fitted with^' a dilation balloon in accordance with the present invention. The cutting assembly 105 includes a cutter 107 having a forwardly extending angular cutting surface 108. An expandable basket 118 carried by guide wire 119 may be opened to limit the travel of cutter 107 and retain any severed stenosis material within the cutter. The cutter 107 is recessed within a housing 109 which includes a housing tail piece ill. Housing tail piece 111 includes a recess 113 into which a nylon wire 115 of dilation balloon 7 may be wrapped. In all other respects, the attachment of the dilation balloon 7 is identical to the attachment described with respect to the embodiment shown in Figure 1. It will be appreciated. however, that the tubular member 8 will have a single angio¬ plasty lumen passing therethrough together with drive cable 9.

Figure 5 shows yet another embodiment of the present invention in which a dilation balloon 7 is combined with a drill type atherectomy device as disclosed in co-pending application Serial No. 117,072, filed November 5, 1987. In this embodiment the cutting assembly 205 includes a collection chamber 215 and a housing 209 formed to receive a cutter bit 207. The collection chamber 215 is located proximally of the housing 209 and bit for collecting the removed stenosis material within the atherectomy device. The cutting tool 207 is carried by the distal extremity of flexible drive cable 9. The cutting bit serves to remove materials from the stenosis and cause the removed materials to be withdrawn into the collection chamber through a plurality of helical fluids 217. Guide wire 69 fastens coaxially through the atherectomy catheter. The mounting of the dilation balloon 7 of this embodiment of the atherectomy catheter is identical to the mounting system described for the preceding two embodiments.

The aforementioned devices may be used in a wide variety of ways. As alluded to earlier, often after cutting with any of the described cutters, loose end or rough edges will remain which can flap into the open flow channel. Therefore, it is desirable to reduce such loose edges. After the cutting bit has been used to remove a portion of the stenosis to either widen or create a flow path through an artery (or other similar sized vessel) , the atherectomy catheter 1 may be advanced so that dilation balloon 7 is disposed directly beside the rough edges. Valve 25 is then switched such that the fluid source (riot shown) communicates with dilation balloon 7 to inflate the balloon thereby dilating the vessel and compressing any loose edges into the body of the vessel.

It should be appreciated that a similar technigue can be used to further expand a vessel after a flow path the size of a cutter has been opened. (Particularly with cutters such as those shown in Figures 3 and 4.) In such a method of operation, an initial cut made with a cutting device to open a channel through the vessel. The catheter is then advanced so that the dilation balloon underlies an area sought to be

*expanded. Valve 25 is switched into communication with angioplasty port 15 and fluid is pumped through angioplasty lumen 50 into dilation balloon 7 thereby expanding the balloon and stretching the vessel, as well as compressing the εtenosed portion of the vessel walls to create a larger flow path.

Additionally, it will be appreciated, that in some circumstances, it may be desirable to firmly secure the cutting assembly 5 in place when cutting is occurring. In the embodiment shown in Figure 1, atherectomy balloon 40 is used to position the cutter. It also may serve to secure the cutting assembly in place. However, the embodiment shown in Figures 3 and 4 do not have any such attaching mechanism and therefore, if it is desirable to keep the cutting tool in place, dilation balloon 7 can be expanded before cutting proceeds. It will be appreciated that since these cutters operate at the end of an extended flexible tubular member, such anchoring may often be desirable since in some circumstances it is difficult to generate sufficient force to put the cutter through a stenosis (particularly calcified stenoses) absent some form of anchoring.

Although only a few embodiments of the present invention have been described, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be appreciated that the specific proximal actuator assembly disclosed can be widely varied to affect the reguired motion for the drive cable and introduction of the necessary fluids. Similarly, the specific construction of the cutting assembly may be varied extensively within the teachings of the present invention while retaining their useful benefit of expanding a channel distally of the dilation balloon. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.

Claims

IN THE CLAIMS ; -12-

1. In an atherectomy catheter for removal of at least a portion of a stenosis within a vessel, an elongate flexible tubular member having at least one lumen extending therethrough and having proximal and distal extremities, the tubular member

5 being adapted for insertion into the vessel, flexible drive means disposed within the tubular member for rotational movement within the tubular member, a proximal actuator means for rotating said flexible drive means within the tubular member, and a cutter carried by the distal extremity of the 0 flexible drive means for removing at least a portion of the stenosis, an inflatable dilation balloon carried by the tubular member proximally of the cutter and having the interior of the balloon in communication with the lumen in the flexible tubular member, and means for inflating and deflating the dilation 5 balloon to further reduce the stenosis.

2. An atherectomy catheter as recited in Claim 1 wherein said dilation balloon is mounted coaxially on the tubular member.

3. An atherectomy catheter as recited in Claim 2 wherein said dilation balloon circumscribes the tubular member.

204. An atherectomy catheter as recited in Claim 1 further comprising: flexible guiding means extending forward of the cutter for guiding the cutter to travel axially within the vessel; and collection means for collecting the removed stenosis 25 material.

5. An atherectomy catheter as recited in Claim 4 wherein said cutter and flexible drive means are movable axially relative to the tubular member.

6. An atherectomy catheter as recited in Claim 5 further 30 comprising a generally cylindrical housing carried by the distal extremity of the tubular member, the housing being formed with a cutout extending longitudinally of the housing on one side of the housing, said cutter being disposed within the housing.

7. An atherectomy catheter as recited in Claim 5 further comprising a generally cylindrical housing carried by the distal extremity of the tubular member for receiving the cutter, wherein said cutter has a forwardly extending annular cutting edge, said cutter being movable to an axial position wherein the cutting edge is spaced forwardly from the distal extremity of the housing.

8. An atherectomy catheter as recited in Claim 5 wherein said cutter has a plurality of inclined cutting edges arranged to converge towards their distal extremities.

9. An atherectomy catheter as recited in Claim 1 wherein said flexible tubular member includes a torgue transmitting layer and a shrink fit jacket, said shrink fit jacket being sized to extend over the proximal extremity of the inflatable dilation balloon to secure the dilation balloon in place.

10. An atherectomy catheter as recited in Claim 9 further comprising: a housing for receiving the cutter, the housing having an exterior recess; and a wire carried by the distal extremity of the inflatable balloon for coupling the distal extremity of the inflatable member to the exterior recess of the housing.

11. A method of reducing stenosis within a vascular vessel to enlarge a fluid flow path within the vessel using an atherectomy device having a cutter and a dilation balloon carried proximally of the cutter, the method comprising the steps of: inserting the catheter into the vessel and advancing the cutter to the region of the stenosis; cutting a portion of the stenosis from the vessel wall using the cutter; advancing the dilation balloon into the region of the ^•vessel where the stenosis material was removed; and expanding the balloon to further expand the flow path where at least some cutting has occurred.

12. A method as recited in Claim 11 further comprising the step of collecting the removed stenosis material.

13. An atherectomy device for expanding the fluid flow path through a stenosis within a vessel having walls and removing at least a portion of the stenosis, the device including: an elongated flexible tubular member having at least one lumen extending therethrough a torgue transmitting layer, and a shrink fit jacket, the tubular member having proximal and distal extremities and a longitudinal axis; flexible drive means disposed within the tubular member and adapted for axial and rotational movement therein; a proximal actuator assembly for rotating and translating said flexible drive means relative to the longitudinal axis of the tubular member; a cutter carried by the distal extremities of the flexible tubular member for removing a portion of the stenosis; a housing carried by the distal extremity of the tubular member for receiving the cutter; an inflatable dilation member carried by the tubular member proximally of the housing and having an interior chamber that is in fluid communication with the lumen the inflatable dilation member for dilating the vessel walls to expand the fluid flow path; and means for inflating and deflating the inflatable dilation member. wherein the shrink fit jacket is sized to extend over the proximal end of the inflatable dilation member for securing the inflatable dilation member in place.

14. An atherectomy device as recited in Claim 13 wherein said inflation means is carried by the proximal actuator assembly.