# US 5,344,419 A · Apparatus and method for making a diffusing tip in a balloon catheter system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,419 A - Document ID: US5344419A - Status: Granted - Kind: A - Application number: 08/052,368 - Filed: 1993-04-23 - Granted: 1994-09-06 - Earliest claimed: 1993-04-23 - Assignees: Wayne State University - Inventors: James R. Spears - Web page: https://patentgrep.com/patent/US5344419A ## CPC - A61B 18/245: {for removing obstructions in blood vessels or calculi} - A61B 2017/22058: {reflective} - A61B 2017/22064: {transparent liquid} - A61B 2018/2261: {with scattering, diffusion or dispersion of light} - A61N 5/0601: {Apparatus for use inside the body} - A61N 5/062: {Photodynamic therapy, i.e. excitation of an agent} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## 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 ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 1) The method of claim 1 wherein the step of applying a coating to the medium is performed after curing the adhesive translucent medium. ### Claim 6 (depends on 1) 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. ### Claim 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. ### Claim 8 (depends on 7) The method of claim 7 wherein the mass of microballoons is less than 10 micrograms. ### Claim 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. ### Claim 10 (depends on 9) 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. ### Claim 11 (depends on 9) The laser balloon catheter of claim 9 wherein the inflatable balloon is made of PET. ### Claim 12 (depends on 9) The laser balloon catheter of claim 9 wherein the inflatable balloon is made of a high density polyethylene. ### Claim 13 (depends on 9) The laser balloon catheter of claim 9 wherein the inflatable balloon is made of nylon. ### Claim 14 (depends on 10) 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. ### Claim 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. ### Claim 16 (depends on 15) The method of claim 15 wherein the optical fiber is a silica fiberoptic. ### Claim 17 (depends on 15) The method of claim 15 wherein the paste is a fluoropolymer paste to provide a relatively high transmission of ultraviolet radiation. ### Claim 18 (depends on 15) The method of claim 15 wherein the tubing is a thin-walled fluoropolymer tubing to provide a relatively high transmission of ultraviolet radiation. ### Claim 19 (depends on 15) 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. ### Claim 20 (depends on 15) 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. ### Claim 21 (depends on 9) 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.