Apparatus and method for making a diffusing tip in a balloon catheter system

• US 5,344,419 A
• Filed: 04/23/1993
• Issued: 09/06/1994
• Est. Priority Date: 04/23/1993
• Status: Expired due to Fees

• Current Assignee: Wayne State University
• Original Assignee: Wayne State University
• Inventors: Spears, James R.
• Primary Examiner(s): ASCHENBRENNER, PETER
• Application Number:
  US08/052,368
• Time in Patent Office: 501 Days
• Field of Search: 606/2, 606/3, 606/7, 606/13-17, 128/395-398
• US Class Current: 606/15
• CPC Class Codes: A61B 18/245 for removing obstructions in blood vessels or calculi
• CPC Class Codes: A61B 2017/22058 reflective
• CPC Class Codes: A61B 2017/22064 transparent liquid
• CPC Class Codes: A61B 2018/2261 with scattering, diffusion or dispersion of light
• CPC Class Codes: A61N 5/0601 Apparatus for use inside the body
• CPC Class Codes: A61N 5/062 Photodynamic therapy, i.e. excitation of an agent

Abstract

An apparatus and method are disclosed for making a laser balloon catheter (10) having a diffusing tip (24) for propagating a uniform cylindrical pattern of laser energy. Included in the catheter are an elongated flexible tube (12) with an inflatable balloon (14) connected to the tube and means for inflating (16) and deflating (18) the balloon. A central channel (20) is disposed within the balloon and coupled to the tube. An optical fiber (22) with the diffusing tip at its distal end delivers laser radiation through the balloon to tissue to be treated. The method comprises the steps of etching the distal end of the optical fiber to form an etched portion thereof, cladding the etched portion with a medium which secures the optical fiber to the central channel, and microballoons which diffuse the laser radiation radially from the optical fiber, thereby substantially avoiding axial propagation and heating of blood forward of the optical fiber.

Claims

1. A method for making a laser balloon catheter having an elongated flexible tube with an inflatable balloon connected to the tube, means for inflating and deflating the balloon, a central channel disposed within the balloon and coupled to the tube, an optical fiber with a diffusing tip at its distal end for delivering laser radiation through the balloon to tissue to be treated, the method comprising the steps of:

etching the distal end of the optical fiber to form an etched portion thereof;

cladding the etched portion with an adhesive translucent medium which secures the optical fiber to the central channel so that the optical fiber is eccentrically positioned in relation to the central channel; and

applying to the medium a coating which surrounds the central channel, the coating having suspended therewithin a plurality of microballoons for diffusing the laser radiation radially from the optical fiber, so that a cylindrical pattern of diffused laser energy is formed about a predetermined axial length of the central channel.

2. The method of claim 1 wherein the step of etching the distal end of the optical fiber comprises etching a portion of about 7 millimeters in length.

3. The method of claim 1 wherein the step of etching the distal end of the optical fiber comprises the step of etching in hydrofluoric acid.

4. The method of claim 1 wherein the step of cladding the etched portion with an adhesive translucent medium comprises the step of cladding with an epoxy.

5. The method of claim 1 wherein the step of applying a coating to the medium is performed after curing the adhesive translucent medium.

6. The method of claim 1 wherein the microballoons are glass and have an average outside diameter of 0.001 inches and a wall thickness of about 0.0001-0.0002 inches.

7. A method for making a laser balloon catheter having an elongated flexible tube with an inflatable balloon connected to the tube, means for inflating the balloon, means for deflating the balloon, a central channel disposed within the balloon and coupled to the tube, an optical fiber with a diffusing tip at its distal end for delivering laser radiation through the balloon to tissue to be treated, the method comprising the steps of:

etching the distal end of the optical fiber to form an etched portion thereof;

caddying the etched portion with an adhesive translucent medium which secures the optical fiber to the central channel so that the optical fiber is eccentrically positioned in relation to the central channel, the medium having suspended therewithin a plurality of microballoons for diffusing the laser radiation radially from the optical fiber, so that a cylindrical pattern of diffused laser energy is formed about the central channel while substantially avoiding excessive axial propagation and heating of blood distal to the balloon.

8. The method of claim 7 wherein the mass of microballoons is less than 10 micrograms.

9. A laser balloon catheter comprising:

an elongated flexible tube having a distal end and a proximal end;

an inflatable balloon secured to the flexible tube proximate the distal end;

means for inflating and deflating the balloon;

a central channel disposed int eh balloon and coupled to the flexible tube;

an optical fiber mounted eccentrically in relation to the central channel for delivering laser radiation through the tube and balloon to tissue to be treated; and

a diffusing tip located at the distal end of the optical fiber for directing laser radiation radially though the balloon, the diffusing tip being located within the balloon between the central channel and the balloon surface and including microballoons for limiting eclipsing of the laser radiation by the central channel and for forming a cylindrical pattern of diffused laser energy about the central channel.

10. The laser balloon catheter of claim 9 wherein the microballoons which surround the central channel and the distal end of the optical fiber direct laser radiation radially outwardly from the central channel.

11. The laser balloon catheter of claim 9 wherein the inflatable balloon is made of PET.

12. The laser balloon catheter of claim 9 wherein the inflatable balloon is made of a high density polyethylene.

13. The laser balloon catheter of claim 9 wherein the inflatable balloon is made of nylon.

14. The laser balloon catheter of claim 10 including a radio opaque layer disposed on an outer surface of the central channel for reflecting laser radiation.

21. The laser balloon catheter of claim 9 further comprising a plurality of optical fibers for delivering laser radiation through the tube and balloon to tissue to be treated, the plurality of optical fibers being distributed around a circumference of the central channel.

15. A method for making a laser balloon catheter having an elongated tube with an inflatable balloon connected to the tube, means for inflating and deflating the balloon, a central channel disposed within the balloon and coupled to the tube, an optical fiber with a diffusing tip at its distal end for delivering the laser radiation through the balloon to tissue to be treated, the method comprising the steps of:

etching the distal end of the optical fiber to form an etched portion thereof;

applying a layer of a paste to the etched portion of the optical fiber for scattering the laser radiation in a radial direction;

sandwiching the optical fiber between two layers of tubing, an outer layer of which is heat shrinkable; and

heat shrinking the outer layer, thereby embedding the optical fiber in the layers of tubing so that the optical fiber is eccentrically positioned in relation to the central channel, and thereby diffusing the laser radiation radially from the optical fiber, so that a cylindrical pattern of diffused laser energy is formed about the central channel while substantially avoiding excessive axial propagation and heating of blood distal to the balloon.

16. The method of claim 15 wherein the optical fiber is a silica fiberoptic.

17. The method of claim 15 wherein the paste is a fluoropolymer paste to provide a relatively high transmission of ultraviolet radiation.

18. The method of claim 15 wherein the tubing is a thin-walled fluoropolymer tubing to provide a relatively high transmission of ultraviolet radiation.

19. The method of claim 15 wherein the laser radiation diffused radially from the optical fiber includes more than 50% of radiation in the UV range.

20. The method of claim 15 wherein the step of sandwiching the fiberoptic between two layers of tubing comprises the step of recladding the etched portion with a fluoropolymer, thereby conferring increased mechanical strength and a reduction in brittleness to the optical fiber.