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

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.

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.