WO1993015672A1

WO1993015672A1 - Multi-fiber laser catheter

Info

Publication number: WO1993015672A1
Application number: PCT/US1993/001062
Authority: WO
Inventors: Steven D. Savage; Gregory G. Brucker
Original assignee: Angelase, Inc.
Priority date: 1992-02-05
Filing date: 1993-02-05
Publication date: 1993-08-19

Abstract

A multi-fiber laser catheter (10) for irradiation of human myocardial tissue containing a movable feedback mechanism (26) for monitoring the damage created by laser irradiation both electrophysiologically and thermally. Means for sensing distal temperature are provided in the form of a plurality of temperature sensors (52, 54). A conically shaped member (48) within the annular tip (24) causes the individual optic fibers (30a-30n) to be configured such that they are not parallel to the axis of the catheter, providing a more diffuse pattern of laser energy. Cooling means and flushing means are provided for cooling the tissue and tip (24), and removing blood from the field of view of the laser energy during the irradiation process.

Description

MULTI-FIBER LASER CATHETER

CROSS REFERENCES TO CO-PENDING APPLICATIONS

U.S. Patent Application Serial No. 07/608,281, filed November 2, 1990, and U.S. Patent Application Serial No. 07/608,290, filed November 2, 1990, are commonly assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION Field of the Invention - The present invention pertains to a medical device, and more particularly, pertains to a catheter with multiple optical fibers for carrying laser energy to a site within a patient having tissue to be treated.

Description of the Prior Art - It is known in the art to use laser energy for medical purposes. A common medical application is in the irradiation of tissue. For external use, the laser energy may be directly applied. However, when the procedure requires irradiation of tissue which is not readily accessible, the use of a laser catheter is common. A typical application for a laser catheter is in the cardiovascular system. U.S. Patent Nos. 4,997,431 and 4,985,028, both issued to Isner et al., show laser catheters particularly adapted for laser treatment within the cardiovascular system.

It is convenient to utilize a guide wire and /or fixation wire in accordance with positioning and maintaining position of a laser catheter. The above referenced patents issued to Isner et al., and incorporated herein by reference teach the use of a wire for those purposes. The irradiation of tissue must be accomplished with great precision as the danger of also irradiating other adjacent tissue is always present, especially when the process occurs remotely at the distal end of a relatively long catheter. U.S. Patent No. 4,785,806 issued to Deckelbaum discusses a system whereby an attempt is made to distinguish different types of tissue using ultra violet fluoroscopy. A similar approach is proposed in U.S. Patent No. 4,718,417 issued to Kittrell et al. Spectral analysis of reflected light energy is also proposed in U.S. Patent No. 4,669,467 issued to Willett et al.

However, none of these approaches monitor the operation of the irradiation activity itself. It is the production and absorption of laser radiation which produces controlled heating that actually treats the unwanted tissue. The prior art ^• discusses distinguishing the tissue prior to treatment and analyzing the products of the procedure following irradiation, but none of the references measure the irradiation activity directly during the heating process.

In those procedures wherein multiple optical fiber energy delivery is possible, great flexibility is achieved in providing the therapy. The above referenced patents to Kittrell et al., and Willett et al., discuss multiple fiber systems.

SUMMARY OF THE INVENTION The general purpose of the present invention is to provide a laser catheter with a multiple fiber laser assembly including a temperature sensing means, a cooling means and a flushing means.

According to one embodiment of the present invention, there is provided a catheter with a central lumen consisting of a plastic tube approximately 100 cm long to which is affixed at its distal end a metallic or plastic inner ring. The inner ring is shaped in a conical manner with the base of the cone directed distally of the catheter. The central lumen contains a fixation wire which consists of a central wire core of a 0.010 inch diameter stainless steel to which is attached multiple temperature sensors. Typically two thermocouples are affixed to the fixation wire at the distal end at a predetermined location from the tip of the wire. This assembly is enclosed in a PTFE tubular sheath and then in a stainless steel sheath extending from a Y-connector. The distal end of the centrally aligned fixation wire assembly serves as one pole of a bipolar sensing probe, and is used to monitor the effect of the tissue irradiation both electrophysiologically and thermally.

An outer sheath, typically 6 French in diameter, is used to house the tip assembly and the inner tubular sheath, and is made of a plastic tube to which is attached at its distal end an outer brass ring. The outer ring serves as the second pole of a bipolar sensing element. The annular space between the inner and outer tubes, or sheaths, serves as conduit for a flushing media such as sterile saline solution. This liquid cools the tissue and also removes blood from the field of view of the laser energy during the irradiation process.

Contained within the annular space of the inner and outer plastic tubes are a plurality of optical fibers for carrying the laser energy to the tissue to be radiated, such as myocardial tissue.

At the distal end, the fibers are configured such that they are not parallel to the axis of the catheter. This provides a more diffuse pattern of the laser energy than the diffusion ordinarily associated with an optical fiber. In this way, a larger surface area is irradiated than is possible with a single fiber. In addition, multiple fibers also provide a catheter having a lower axial stiffness than single fiber systems for a given total energy capacity.

At the proximal end is a multiple arm Y-connector. The central port of the Y-connector contains the interface for the fixation wire, which consists of two distinct parts. A mechanical plunger extends from the most proximal branch for retracting the fixation wire. Attached to the inner part of the plunger are two optional thermocouple junction blocks. These blocks allow for quick connection of the temperature sensors at the tip of the fixation wire to their measuring instruments.

One branch of the Y-connector is attached to the annular space between the inner and outer plastic tubes. This port is used to pass a coolant and flushing medium along the fibers and out the tip. This flow keeps all materials of the delivery device cool to prevent mechanical degradation or loss of structural integrity from overheating and also to bath the myocardial tissue being treated. This helps prevent photocoagulation of blood and also reduces tissue surface temperature to reduce likelihood of carbonization and vaporization.

The other branch of the Y-connector houses the multiple optical fibers. This connection seals against water flow and fixes the optical fiber relationship to the laser delivery device.

A metal ring is provided at one of the Y-connector ports which provides an electrical connection to the tip of the laser catheter. This can be used as an electrode for electrophysiological monitoring of cardiac potentials.

Significant aspects and features of the present invention include the diffusing of concentrated laser light. Other significant aspects and features of the present invention include a flexible catheter, monitoring of thermal response of the tissue, the use of standard fibers, a larger planar area of treatment, and a simple distal tip yielding a smaller more reliable catheter. Having thus described the embodiments of the present invention, it is the principal object hereof to provide a multi-fiber laser catheter including temperature sensing means, cooling means, and flushing means.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: FIG. 1 illustrates a plan view of a multi-fiber laser catheter of the present invention;

FIG. 2 illustrates a cutaway view of the syringe and Y- connector;

FIG. 3 illustrates a cross-sectional view of the catheter tip area along line 3-3 of FIG. 1;

FIG. 4 illustrates a view along line 4-4 of FIG. 3; and, FIG. 5, an alternative embodiment, illustrates a cross- sectional view of the distal end including a fixed thermocouple assembly. DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a plan view of a multi-fiber laser catheter 10. The multi-fiber laser catheter 10 includes a dual port Y- connector 12 and a syringe 14 coupled to each other by a coupler nut 16. A stainless steel tube 18 is affixed to and extends from one end of the dual port Y-connector 12. A syringe plunger 20 is integral to the syringe 14.

A plastic catheter tube 22, about 100 cm long, secures to one end of the stainless steel tube 18, and annular metallic tip 24 secures to the distal end of the plastic catheter tube 22. An axially movable fixation wire assembly 26 extends through and from the annular metallic tip 24. Multi-fiber optic cable 30 passes through the flush port 28 of the dual port Y-connector 12. The stainless steel tube 18 is coupled to the plastic catheter tube 22 which in turn connects with the annular metallic tip 24. A plurality of wires including wires 34, 36 and 38 pass through a stainless steel tube 40 which is coaxial to the syringe 14, syringe plunger 20, the dual port Y-connector 12, the stainless steel tube 18, the plastic catheter tube 22, and is mated within the annular metallic tip 24 as later described in detail.

Wire 34 is a stiffening wire and wires 36 and 38 are wires leading to thermocouples on the fixation wire assembly 26. Another wire 32, as shown in Fig. 2, aligns in the flush port 28 of the dual port Y-connector 12 and connects electrically to an outer metallic ring or tip 24. Wire 32 passes through the stainless steel tube 18, the plastic catheter tube 22 and connects electrically to the annular metallic tip 24 to provide means of recording' electrical potentials inside the heart. Bipolar mapping can be carried out by measuring local activation potentials of the endocardial surface. In conjunction with standard EP monitoring equipment, the signals generated can be used to determine electrophysiological properties of the tissue that lies between the electrodes. During ablation, the signals can be watched for changes.

The flush port 29 of the dual port Y-connector 12 is a coolant port, and is connected to the interior regions of the dual port Y-connector 12, and more importantly, to the interior lumen of the stainless steel tube 18 and the attached plastic catheter tube 22. A flushing fluid is routed through the flush port 29 along the multi- fiber optic cable 30, through the stainless steel tube 18 and the plastic catheter tube 22 and out of the annular metallic tip 24 as described later in detail.

FIG. 2 illustrates a cutaway view of the syringe 14 and dual port Y-connector 12 where all numerals correspond to those elements previously described. A stainless steel tube 40 aligns coaxially within and affixes to the syringe plunger tube 41. The wires 34, 36 and 38 align in and are secured within the lumen of the stainless steel tube 40. End 40a of the stainless steel tube 40, which includes wires 34, 36, and 38, slidingly aligns in the lumen 43 of the stainless steel tube 18. The multi-fiber optic cable 30 aligns in the metallic plug 31, tubular plastic member 42 of port 28 of the dual port Y- connector 12, and lumen 43 of the stainless steel tube 18. The multi- fiber optic cable 30 shares the lumen 43 with wires 34, 36, and 38, all of which align in the lumen 43 of the stainless steel tube 18, and in the central lumen 46 of the plastic catheter tube 22 as illustrated in FIG. 3. Actuation of the syringe plunger 20, and hence the attached stainless steel tube 40, causes the wires 34, 36, and 38, which ultimately make up the majority of the structure in the fixation wire assembly 26, to move axially as depicted by the double arrow 47 as illustrated in FIG. 1.

FIG. 3 illustrates a cross-sectional view of the catheter tip area along line 3-3 of FIG. 1 where all numerals correspond to those elements previously described. The metallic tip 24, such as a brass tip, is multi-radiused so that the lesser radius will frictionally engage the lumen 46 of the plastic catheter tube 22. A conically shaped member 48, including a central passageway, aligns coaxially within the annular metallic tip 24 and is aligned longitudinally with and mated to an inner sheath or tubing 50.

A lumen 51 includes the central passageway of the conically shaped member 48 and the interior of the tubing 50, which has a plastic sheath over it. A conically ramped surface 48a of the conically shaped member 48 causes the individual optic fibers 30a- 30n of the multi-fiber optic cable 30 to diverge from the central axis and to be distributed adjacent to the inner circumference of the annular metallic tip 24. Wire 32 is electrically connected to the metallic tip 24 and passes through the lumen 46 to the dual port Y— connector 12 as previously described. The fixation wire assembly 26 slidingly aligns in the lumen 51 and includes thermocouples 52 and 54 embedded or otherwise attached thereto. The thermocouples are used to monitor tissue temperature during irradiation. Typically, irradiation is ceased when temperatures reach about 150° C. The inner tubing 50 encompasses the wires 34, 36, and 38 and terminates within the stainless steel tube 18. The wires 36 and 38 connect electrically to the thermocouples 52 and 54, respectively, and are routed through with the inner tubing 50, the dual port Y-connector 12, and the proximal end 40a of the stainless steel tube 40 as previously described. The fixation wire assembly 26 contains a plurality of thermocouples including the thermocouples 52 and 54. Preferably, at least two thermocouples are used to provide more complete data. Preferably, the thermocouples are located along the fixation wire such that upon penetration of the fixation wire into the tissue, the thermocouples are at the highest temperature. Fixation wire assembly 26 is also adapted for electrical connection to one pole of the bipolar sensing system. The metallic tip 24 provides an electrical connection for the second pole of the electrophysiological monitoring system.

The annular space between the outer plastic catheter tube 22 and the inner plastic tube or sheath 50 serves as a conduit for a flushing media such as sterile saline solution. This liquid cools the tissue and the metallic tip 24, and also^" removes blood from the field of laser energy during the irradiation process.

Because of the need to pass through a rather tortuous passageway of standard catheter designs, the fixation wire assembly 26 is retracted into the metallic tip 24 during advancement of the catheter. Preferably, the wire is coated with TEFLON to allow for easy sliding in the inner lumen. With the fixation wire assembly 26 retracted, the profile of the metallic tip 24 presents a very low profile device whose leading edge is smooth and free of any protrusions which would cause the catheter to hang-up during its passages through portions of the human anatomy. Upon reaching the desired depth of penetration, the fixation wire assembly 26 is deployed to penetrate the myocardial surface. The fixation wire assembly 26 may also serve a bipolar mapping assembly.

FIG. 4 illustrates a view along line 4-4 of FIG. 3 where all numerals correspond to those elements previously described. Illustrated in particular is the distribution of the individual fiber optic cables 30a-30n about the inner circumference of the annular metallic tip 24. Sterile saline solution passes through the lumen 46 between the outer plastic tubing and the inner plastic tubing and the unramped portion of the conical member 48 as illustrated in FIG. 3.

Cooling sterile saline fluid flow continues along and between the ramped surface 48a and the interior circumference of the annular metallic tip 24, as well as along the individual fiber optic members 30a-30n to exit between the areas aligned between the ends of the individual fiber optic members 30a-30n and the inner circumference of the metallic tip 24 and the largest diameter of the conical member 48. FIG. 5 illustrates an alternative embodiment of the distal end of the catheter system including a fixed fixation wire assembly 70 where all numerals correspond to those elements previously described. The fixation wire assembly is fixed in the position illustrated and is used in an environment where retraction of the fixation wire is not required.

Having thus described the preferred embodiments of the present invention, those of skill in the art will be readily able to practice yet other embodiments within the scope of the claims hereto attached.

Claims

WHAT IS CLAIMED IS:

1. A laser catheter comprising: a. a catheter body having a proximal end and a distal end and at least one lumen extending therethrough; b. a multi-fiber optic cable having a proximal end and a distal end located within said catheter body and having a plurality of individual optical fibers; c. means attached to said distal end of said catheter body for maintaining said distal end of said optical fibers at different angles with respect to said longitudinal axis of said catheter body; and, d. a fixation wire in said at least one lumen extending past said distal end of said catheter body, said fixation wire having a proximal end and a distal end, said fixation wire having a first tissue temperature sensor fixedly attached to said distal end.

2. A laser catheter according to claim 1 wherein said fixation wire further comprises a second temperature sensor fixedly attached to said distal end of said fixation wire.

3. A laser catheter according to claim 2 further comprising means coupled to said distal end of said catheter body for supplying a flushing fluid.

4. A laser catheter according to claim 3 further comprising a metallic tip coupled to said distal end of said catheter body.

5. A laser catheter according to claim 4 further comprising means coupled to said metallic tip for coupling said metallic tip to an electrophysiological monitor.

6. A laser catheter according to claim 5 wherein said fixation wire is fixedly attached to said catheter body.

7. A laser catheter according to claim 5 wherein said fixation wire is slidably located within said catheter body.

8. The laser catheter of claim 1 wherein said means attached to said distal end of said catheter body comprises an annular tip member having a central passageway of constant diameter and an annular recess in which said distal end of each of said individual optical fibers are maintained at a different angle with respect to said longitudinal axis of said catheter body.

9. The laser catheter of claim 8 wherein said annular recess is formed between the circumferential inner wall of said tip member and an inner conically-shaped member.

10. The laser catheter of claim 9 wherein said central passageway is formed through said inner conically-shaped member.

11. A laser catheter comprising: a. a catheter body having a proximal end, a distal end, a central axis and a catheter body lumen; b. a catheter tip portion having a tip portion lumen, said tip portion being affixed to said distal end of said catheter body such that said tip portion lumen aligns with said catheter body lumen; c. a plurality of optic fibers housed in said catheter body lumen and extending into said tip portion lumen; d. means in said tip portion lumen for supporting said optical fibers therein in a position deviant from along said catheter body central axis; and, e. a fixation wire in said catheter body lumen extending past said distal end of said catheter body, said fixation wire having a proximal end and a distal end, said fixation wire having a first tissue temperature sensor fixedly attached to said distal end.

12. The laser catheter of claim 11, wherein said means in said tip portion comprises a tube in said catheter body lumen, said tube having a proximal end and a distal end, the distal end of which has a portion of increasing radius relative to said proximal end, the outer surface of said tube defining with the inner surfaces of said catheter body and said catheter tip portion an annular space in which said plurality of optic fibers are housed.

13. The apparatus of claim 11, further comprising electrophysiological sensing means in communication with said catheter tip portion.

14. A method of irradiating tissue inside a human body, comprising: a. irradiating said tissue with laser energy; b. monitoring through thermal indicia generated during said irradiation, the extent of said irradiation of said tissue; and c. ceasing said irradiation when said monitoring indicates that said irradiation is complete.

15. The method of claim 14 wherein said radiating is accomplished by entering said human body percutaneously with a laser catheter.

16. The method of claim 14 wherein said tissue is endocardial tissue, and wherein said monitoring comprises sensing the local activation sites of said endocardial tissue.

17. The method according to claim 14, further comprising monitoring, through electrophysiological indicia generated during said irradiating, the extent of said irradiation.

18. The method according to claim 17, wherein said irradiation is ceased when said electrophysiological indicia reads as a negative value.