Focusing element for plasma system to disrupt vascular lesions

A method for generating pressure waves to induce fractures at a treatment site within or adjacent a vessel wall, the method comprising the steps of:

• advancing a catheter and a first light guide to the treatment site, the catheter comprising an elongate shaft and a balloon coupled to the elongate shaft, the first light guide being disposed along the elongate shaft at least partially within the balloon, the first light guide being in optical communication with a light source and a balloon fluid, the first light guide including a first focusing element located at a distal portion of the first light guide, the distal portion of the first light guide being positioned within the balloon fluid;
• and
• activating the light source to direct light from within the first light guide to a first location at a first distance away from the distal portion of the first light guide so that plasma formation in the balloon fluid is initiated away from the distal portion of the first light guide and so that rapid bubble formation occurs, thereby imparting pressure waves upon the treatment site;
• wherein the first location is spaced away from the distal tip and is centered on a longitudinal axis of the first light guide.

A catheter system for imparting pressure to induce fractures in a treatment site within or adjacent a vessel wall, comprising:

• a catheter that is configured to advance to the treatment site, the catheter comprising an elongate shaft and a balloon that is coupled to the elongate shaft, the balloon comprising a balloon wall;
• a first light guide that is disposed along the elongate shaft and at least partially within the balloon, the first light guide being in optical communication with a light source and a balloon fluid, the first light guide comprising a first diverting feature positioned at a distal portion of the first light guide, the distal portion of the first light guide being positioned within the balloon fluid;
• and
• a first focusing element positioned at the distal portion of the first light guide so that the first diverting feature is in optical communication with the first focusing element;
• wherein the first diverting feature is configured to direct light from within the first light guide toward the first focusing element, and the first focusing element is configured to direct light from within the first light guide to a first location at a first distance from the distal portion of the first light guide and toward the balloon wall so that plasma formation in the balloon fluid is initiated away from the distal portion of the first light guide and so that rapid bubble formation occurs, thereby imparting pressure waves upon the treatment site, the first location being spaced away from a longitudinal axis of the first light guide.