WO1990011722A1

WO1990011722A1 - Apparatus for positioning and stabilizing a catheter

Info

Publication number: WO1990011722A1
Application number: PCT/US1990/001851
Authority: WO
Inventors: Michael A. Martinelli; William E. Hagel
Original assignee: Intra-Sonix, Inc.
Priority date: 1989-04-04
Filing date: 1990-04-03
Publication date: 1990-10-18
Also published as: AU5522190A

Abstract

A bearing catheter (20) for stabilizing and positioning a therapeutic/diagnostic catheter (100) at a predetermined location within a lumen (210). The bearing catheter (20) comprises a tube (22) sized to receive the therapeutic/diagnostic catheter (100) so that the latter is free to move axially and rotationally within the tube (22) while remaining substantially fixed radially with the tube (22). The bearing catheter tube (22) has a wall thickness selected so that, and is made from a material chosen so that, a laser beam of selected wavelength can be transmitted through the tube with little or no absorption of the laser energy so that the tube (22) will not be damaged and so that ultrasonic imaging signals may be transmitted and received through the tube (22).

Description

APPARATUS FOR POSITIONING AND STABILIZING A CATHETER

This is a continuation-in-part of U.S. Patent Application Serial No. 333,101, filed April 4, 1989, now

Field of the Invention

The present invention relates generally to catheters, and more particularly to apparatus for stabilizing a catheter in a blood vessel or other lumen.

Background of the Invention

Catheters comprising a mechanism for immobilizing the body of the catheter against an interior wall of a lumen in which the catheter is disposed are known, as illustrated in U.S. Patents Nos. 4,733,669 and 4,794,931. Typically, such mechanisms comprise a unitary, radially-expandable member, such as a balloon or a single flexible wire, attached to the front or distal end of the catheter. The balloon or flexible wire is manipulated so as to force the end portion of the catheter against the interior wall of the lumen, thereby securing the catheter in place.

These mechanisms function satisfactorily when the objective is to wedge the body of the catheter against the sidewall of the lumen. The radially-expandable positioning mechanisms disclosed in the above-mentioned U.S. Patents cannot be satisfactorily employed, however, when for example, it is desirable to axially and/or rotationally move the catheter within the lumen. Such axial and rotational movement is required in connection with the use of a catheter capable of generating ultrasonic energy for imaging, and laser energy for ablation of diseased portions on, the interior of the lumen in which the catheter is disposed. Such a catheter is described in U.S. Patent No.4,821,731 to Martinelli, et al. (the '731 catheter).

The insertion of known diagnostic/therapeutic catheters in a lumen may abrade or otherwise physically damage the wall of the lumen due to the relatively inflexible nature of the catheter. Additionally, once the diagnostic/therapeutic catheter has been inserted so that its distal end is positioned adjacent a diseased portion of the lumen, the catheter is moved repeatedly both axially and rotationally in conjunction with the therapeutic and diagnostic procedures performed using the catheter. This axial and rotational movement can cause additional abrasion and other physical damage of the lumen.

Objects and Summary of the Invention

A primary object of the present invention is to provide a device for stabilizing a diagnostic/therapeutic catheter without wedging the catheter against the wall of the lumen, and for permitting such a stabilized catheter to be moved axially and rotationally within a lumen.

Another object of the present invention is to provide a device for stabilizing catheters of the type disclosed in U.S. Patent No. 4,821,731 so that portions of the lumen wall can be ultrasonically imaged,.

Yet another object of the present invention is to provide a device for stabilizing catheters of the type disclosed in U.S. Patent No. 4,821,731 within a lumen so that laser energy can be precisely directed from within the lumen toward predetermined areas of the lumen.

Still another object of the present invention is to provide a device for protecting a lumen so as to permit a diagnostic/therapeutic catheter to be moved axially and rotationally in the lumen without physically damaging the lumen.

These and other objects are achieved by a bearing catheter comprising a hollow, preferably flexible tube member shaped for receiving a catheter so that the catheter is free to move axially and rotationally within the tube member along and about an axis of movement, while being restrained from moving radially within the tube member. The tube member is sized so as to facilitate its movement through a curved lumen with branches, such as a coronary artery. Due to the sinuous nature of such lumens, after the tube member has been inserted some distance into the lumen, the tube member will be substantially immobilized within the lumen. In turn, because the catheter is sized to make a close-sliding fit in the tube member, once the latter has been inserted into the curved lumen, and hence is radially stabilized, the catheter is also radially stabilized relative to the lumen in which it is disposed.

The wall of the tube member is constructed of a material which is transmissive to laser energy so that a laser beam of selected wavelength will pass through the tube wall with little or no absorption. The material of the tube wall is further selected to be highly transmissive to ultrasonic energy so that ultrasonic energy originating from the distal end of a catheter inserted within the tube member will pass through the tube wall, toward a particular part of the lumen. The material of the tube wall transmits a sufficient amount of energy reflected from the particular part of the lumen so that an image of the particular part of the lumen may be created from the received ultrasonic energy.

Brief Description of the Drawings

For a fuller understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in connection with the accompanying drawings wherein:

Fig. 1 is a side elevational view of the bearing catheter of the present invention;

Fig. 2 is a side elevational view of the distal end of one embodiment of the bearing catheter, partly broken away to reveal a diagnostic and therapeutic catheter positioned in the bearing catheter;

Fig. 3 is a schematic plan view of a vascular system, partly broken away to show (1) a diseased portion on the interior wall of a section of the vascular system and (2) the bearing catheter of the present invention, the latter being partly broken away to reveal a diagnostic and therapeutic catheter disposed therein; and

Fig. 4 is a cross-sectional side elevation view of (1) the distal end of one embodiment of the bearing catheter and (2) a guide wire and plug insertion assembly disposed inside the bearing catheter.

Detailed Description of the Invention

Referring to Fig. 1, the present invention is a bearing catheter 20 for receiving and stabilizing the radial position of at least a portion of a diagnostic and therapeutic catheter in a lumen of a living body, while permitting the diagnostic and therapeutic catheter to be moved rotationally and axially within the bearing catheter.

By way of background, an exemplary diagnostic and therapeutic catheter of the type used with bearing catheter 20 is described in U.S. Patent No. 4,821,731 to Martinelli et al. (the '731 patent), and is illustrated generally at 100 in Figs. 2 and 3. Catheter 100 has a cylindrical exterior configuration over the majority of its length and comprises a distal end 102, an optical assembly 104 positioned adjacent the distal end for folding a laser beam transmitted through optical fibers in the catheter so that the laser beam is projected from the catheter along an axis extending transversely to the longitudinal axis of the catheter, and a transducer assembly 106 positioned adjacent the optical assembly.

Referring again to Fig. 1, bearing catheter 20 comprises an elongate flexible tube 22 having a hollow interior 24. The latter is sized so that catheter 100 will slide freely both axially and rotationally within the interior without moving radially relative to the tube. Tube 22 is additionally sized so that it may be caused to slide axially within a selected lumen. In this connection, tube 22 preferably first tapers radially inwardly at shoulder 26 and again at its distal end 28. In one embodiment of the present invention, shoulder 26 is spaced about 10 centimeters from distal end 28. Tube 22 is preferably open at both its distal and proximal ends 28 and 30 to provide access to interior 24.

Preferably, tube 22 is sufficiently long so that the distal end can be positioned at a predetermined location of a lumen.

In accordance with one aspect of the present invention, bearing catheter tube 22 is made from a material that will permit a laser beam of selected wavelength, transmitted from the optical assembly 104 of a catheter 100 disposed within the tube, to be transmitted through the tube wall with little or no absorption so that the tube wall will not be damaged by the laser energy. The material from which tube 22 is made is additionally selected so that "sufficient" ultrasonic energy generated by the ultrasonic transducer assembly 106 of catheter 100 disposed within the tube will pass through the wall of the tube, penetrate and reflect from the tissue forming the wall of the lumen in which the stabilizing tube is disposed, and pass back through the wall of the tube to the ultrasonic transducer assembly. As used above, "sufficient" ultrasonic energy is that amount of energy needed by the imaging system of the ^#731 patent to provide an image of sufficient quality to effect the laser treatment. The actual material and thickness of the bearing catheter tube 22 will vary depending on the wavelength and intensity of the laser beam and ultrasonic beam generated by the catheter 100 used with tube 22. However, when the laser beam transmitted by the optical system 104 of catheter 100 has a wavelength in the mid-infra-red range (i.e., 2-3 microns), two suitable materials for tube 22 are polytetrafluoroethylene ("PTFE") and fluorinated ethylene propylene ("FEP") , fabricated to have a wall thickness ranging from 2 to 6 mils. Of course, other materials of various thicknesses may be satisfactorily employed depending upon the bandwidth requirements of the laser beam and ultrasonic energy transmitted and received by catheter 100.

Tube 22 comprises a front section 32 (Fig. 1) between shoulder 26 and distal end 28. The configuration of front section 32 varies depending upon the material used to fabricate tube 22. When tube 22 is made from a relatively flexible and pliant material such as FEP, its front section 32 typically has an elongate, cylindrical configuration, except adjacent front end 28 where it tapers radially inward.

On the other hand, when tube 22 is made from a relatively stiff material such as PTFE (which is stiffer than FEP) front portion 32 preferably is constructed in the manner illustrated in Fig. 2. More particularly, when tube 22 is fabricated from a relatively stiff material such as PTFE, its front section 32 includes a leading portion 40, an intermediate portion 42 and a trailing portion 44. Portions 40 and 44 have an accordion-like configuration and intermediate portion 42 has a smooth cylindrical configuration. Leading portion 40 preferably tapers radially inwardly at distal end 28. Optionally, trailing portion 44, intermediate portion 42, and leading portion 40 may all gradually taper radially inwardly toward distal end 28.

As those of ordinary skill in the art will appreciate, the relative and absolute lengths of portions 40, 42, and 44 will vary based on the lumen dimension and configuration within which the tube member is to be used. In particular, the length of intermediate portion 42 is typically selected based on (1) the configuration (i.e. straight or curved) of the portion of the lumen in which the therapeutic/ diagnostic catheter is to be used and/or the degree of flexure to which the portion of the lumen of interest is subjected. For example, when the portion of the lumen to be imaged or subjected to laser treatment has a radius of curvature of about 1 cm, intermediate portion 42 has a length of about 0.5 cm, when the lumen portion has a radius of about 2 cm, portion 42 has a length of about 1 cm, and when the lumen portion is substantially straight, portion 42 has a length of about 2 cm. Satisfactory lengths for leading portion 40 and trailing portion 42 are about 3 cm and 10 cm, respectively.

Leading and trailing portions 40 and 44 are provided with an accordion-like configuration so that front portion 32 of tube 22 may be readily passed through a sinuous lumen passageway without kinking. As noted below, catheter 100 is preferably positioned entirely within bearing catheter 20 so that optical assembly 104 and transducer assembly 106 are disposed in intermediate portion 42. As a consequence, intermediate portion 42 has a smooth cylindrical configuration to minimize interference with the transmission of ultrasonic and laser energy therethrough.

When tube 22 is made from PTFE or FEP, the tube tends to expand and contract along its length, depending upon the direction of movement of the tube. Such stretching makes it difficult to maintain catheter 100 in selected registration with bearing catheter 20, since catheter 100 does not stretch appreciably along its length. It is highly desirable to maintain selected registration between portion 42 of catheter 20 and distal end 102 of catheter 100 to ensure the portion 42 of catheter 20 is actually positioned in the location indicated by the image of the lumen in which the catheters are disposed.

Accordingly, in accordance with another aspect of the present invention, to ensure tube 22 does not apprecially expand and contract axially, a braided sheath 50 (Fig. 1) of substantially non-axially extensible fibers is preferably attached to the exterior surface 24 of all but the front portion 32 of tube 22. Suitable materials for the fibers of sheath 50 include stainless steel wire having a diameter of about 1.5 mils.

Referring to Fig. 3, to use either the FEP or PTFE embodiments of bearing catheter 20, the latter is partially inserted into a selected lumen 210, e.g. an artery, through an opening 212 formed in the lumen. Typically, although not necessarily, this partial insertion is effected by first inserting a conventional guide wire (not shown) into the selected lumen 210 until the leading end of the guide wire is positioned past the diseased portion 214 of interest on the inner ^»wall of the lumen. Such portion is typically located by fluoroscopic imaging. Then, a portion of the tube 22 is inserted on the guide wire and moved along the guide wire until the distal end 28 extends beyond the diseased portion 24. The inherent flexibility of the FEP embodiment of tube 22, and the accordion-like configuration of the PTFE embodiment of tube 22, permit the latter to be threaded through a sinuous lumen passageway having multiple branches such as shown in Fig. 3, without kinking. When the PTFE embodiment of Fig. 2 of tube 22 is used, bearing catheter 20 is inserted in lumen 210 so its intermediate portion 42 is positioned adjacent the diseased portion, as shown in Fig. 3.

Catheter 100 is then inserted into hollow interior 24 of tube 22, preferably through the opening in the proximal end 30 of the tube positioned outside the body. As noted above, hollow interior 24 of tube 22 is sized so that catheter 100 can be moved freely relative to the tube and lumen along the length of the hollow interior.

Catheter 100 is moved within stabilizing tube 22 until the former is adjacent the portion 214 of lumen 210 to be examined and possibly treated by a laser beam transmitted from the catheter 100. The site can be determined by fluoroscopic imaging as previously described. After a satisfactory image of portion 214 of lumen 210 is generated using imaging information generated by ultrasonic transducer assembly 106 and processed by the the imaging system of the '731 patent, if the laser treatment is indicated the laser beam is transmitted via optical assembly 104, based on the image data, so as to expose portion 214 to absorptive radiation.

When lumen 210 curves over its length so as to define a sinuous path, and/or repeatedly splits into several lumen of decreasing diameter, as for example the coronary arteries as they extend toward the heart, once bearing catheter 20 has been fully inserted into the lumen, radial movement of the bearing catheter is limited because the latter becomes loosely captivated within the curved walls of the lumen. This stabilization of the catheter is important to generate an accurate image of the lumen 210 and to accurately control the direction of the laser beam transmitted from the catheter 100.

Bearing catheter 20 may optionally be adapted for attachment to a fluid supply source (not shown) . With such an adaptation, fluid can be supplied through the tube or tube member to a selected region within the lumen.

Although bearing catheter 20 is typically inserted in a lumen using a guide wire, as described above, under certain circumstances, for instance when the lumen has a particularly tortuous configuration, it may be desirable to install the bearing catheter using the insertion assembly 300 illustrated in Fig. 4. The insertion assembly 300 is designed to prevent front portion 32 of tube 22 from kinking when the latter is caused to move around a highly curved section of a lumen. Insertion assembly 300 comprises an elongate cylindrical plug 302 and a modified guide wire 304. Plug 302 is made from a relatively rigid material, such as hard rubber, and includes a central bore 306 sized to receive guide wire 304. The outside diameter of plug 302 is slightly less than the inside diameter of front portion 32 of bearing catheter tube 22 so that the former makes a close sliding fit in the latter. The length of plug 302 is about 1 cm when used to install the FEP embodiment of bearing catheter 22, or is substantially equal to the length of intermediate portion 42 of front section 32 when used to install the PTFE embodiment of the bearing catheter.

Guide wire 304 is identical to a conventional guide wire, except that it includes a projection stop 310 spaced a selected distance, such as about 3-6 cm, from the distal or leading end 312 of the guide wire. The precise size and shape of stop 310 may vary so long as the stop extends radially from the guide wire a distance sufficient to permit the projection to engage leading edge 314 of plug 302 to insure the plug is removed from tube 20 when the guide wire 304 is withdrawn from the tube 20.

To install bearing catheter 20 using insertion assembly 300, plug 302 is installed in the bearing catheter so that it is roughly centered in front section 32 of the FEP embodiment or is received in intermediate portion 42 of the PTFE embodiment, as the case may be. Then, the proximal end (not shown) of guide wire 304 is inserted through the opening in the distal end of the tube 22 and into central bore 306 of plug 302 until stop 310 engages the leading end 314 of the plug. Stop 310 is positioned on guide wire 304 relative to the distal end 312 thereof so that when the insertion assembly 300 has been installed in the manner described above, a portion of the guide wire projects through and beyond the opening in the distal end 28 of tube 22. .Bearing catheter 20, with insertion assembly 300 positioned therein, is inserted into the lumen of interest and caused to move inside the lumen until the front section 32 of bearing catheter tube 22 is positioned adjacent the portion of the lumen of interest. Finally, plug 302 and guide wire 304 are removed from the opening in the proximal end 30 of tube 22 by pulling on the proximal end of the guide wire. This pulling is transmitted from the guide wire 304 via stop 310 to plug 302 so that the plug and guide wire are extracted.

Insertion assembly 300 is particularly useful when the lumen in which bearing catheter 20 is to be inserted has a highly tortuous configuration. When the front portion 32 of bearing catheter tube 22 is caused to move around a sharp bend in such a lumen, plug 302 prevents the front portion from kinking.

An important advantage of the bearing catheter system of the present invention, as compared to catheters of the type disclosed in U.S. Patent Nos. 4,733,669 and 4,794,931, is that the present system permits a therapeutic/diagnostic catheter to be supported within a lumen in a stabilized manner so that reliable ultrasonic imaging and laser radiation treatments can be performed while allowing free and rotational movement of the therapeutic/diagnostic catheter within the lumen. With known procedures and apparatus the therapeutic or diagnostic catheter is inserted directly into the lumen without a surrounding protective sleeve. Under such conditions, the possibility exists for the catheter to repeatedly contact and possibly abrade, scrape or otherwise physically damage the lumen. An important advantage of the present invention is that once the bearing catheter tube 22 has been positioned in the lumen, a catheter 100 disposed therein can be moved repeatedly both axially and rotationally without contacting the wall of the lumen.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative and not in a limiting sense.

Claims

What is claimed is:

1. A device for stabilizing a catheter capable of transmitting a laser beam of selected wave length, the device comprising an elongate, flexible tube having:

(a) an axial bore for receiving said catheter so that said catheter is axially slidable and rotatable within said tube;

(b) an exterior surface; and

(c) a wall of predetermined thickness between said axial bore and said exterior surface, wherein said predetermined thickness is chosen and the composition of said wall is selected so that a laser beam of selected wavelength incident on said wall will be transmitted through said wall with little or no absorption of the laser beam so that said beam will not damage said wall.

2. A device according to claim 1, wherein said selected wavelength of said laser beam is about 2 to 3 microns and said predetermined thickness of said wall ranges from 3 to 5 mils.

3. A device according to claim 1, wherein said tube comprises an opening to said axial bore at one end of said tube, said one opening being sized to receive said catheter with a sliding fit.

4. A device according to claim 1, wherein said wall of said tube is made from polytetrafluoroethylene.

5. A device according to claim 1, wherein said wall of said tube is made from a polymer.

6. A device according to claim 1, wherein said wall of said tube is made from fluorinated ethylene propylene.

7. A device according to claim 1, wherein said predetermined thickness of said wall is additionally chosen and the composition of said wall is additionally selected so that sufficient ultrasonic energy can be passed through said wall and back, with little or no reflection of ultrasonic energy so as to permit an ultrasonic image to be formed with reflected ultrasonic energy received back through said wall.

8. A device according to claim 1 wherein a section of said wall adjacent a distal end of said tube has an accordion-like configuration selected to facilitate insertion of said tube into a sinuous lumen.

9. A device according to claim 1 wherein said tube further comprises a distal end and said wall comprises: a) a front portion terminating at said distal end and having an accordion-like configuration; b) a substantially smooth cylindrical intermediate portion adjacent said front portion; and c) a rear portion adjacent said intermediate portion having an accordion-like configuration.

10. A device according to claim 1 further comprising sheath means attached to said wall for substantially preventing said wall from stretching along its axis.

11. A device according to claim 11 wherein said sheath means comprises a braided sheath secured to said exterior surface.

12. A bearing catheter assembly for stabilizing an imaging catheter capable of transmitting a laser beam of selected wavelength, said bearing catheter assembly comprising:

(1) an elongate, flexible tube having:

(a) an axial bore for receiving said catheter;

(b) an exterior surface;

(c) a wall of predetermined thickness between said axial bore and said exterior surface, wherein said predetermined thickness is chosen and the composition of said wall is selected so that a laser beam of selected wavelength incident on said wall will be transmitted through said wall with little or no absorption of the energy of the laser beam so that said beam will not damage said wall; and

(d) an opening to said axial bore at each of the proximal and distal ends of said tube;

(2) a cylindrical plug having a central bore sized to receive said guide wire with a sliding fit, said plug being sized to make a close sliding fit in said axial bore; and

(3) an elongate guide wire sized to be slidably receivable through said openings at said proximal and distal ends and through said axial bore, said guide wire comprising a stop adjacent its distal end for insuring the withdrawal of the plug through the opening of the proximal end when the guide wire is withdrawn from said tube.

13. In combination, a system for gathering image information and transmitting laser energy within a lumen, said system comprising:

(1) a catheter comprising:

(a) means for gathering image information regarding the interior configuration of the lumen; and

(b) means for transmitting a laser beam so that the latter is directed to selected area on an interior surface of the lumen; and

(2) an elongate flexible tube having:

(a) an axial bore for receiving said catheter;

(b) an exterior surface; and

(c) a wall of predetermined thickness between said axial bore and said exterior surface, wherein said predetermined thickness is chosen and the composition of said wall is selected so that a laser beam of selected wavelength incident of said wall will be transmitted through said wall with little or no absorption of the energy of the laser beam so that the laser beam will not damage said wall.