Visible fluorescence spectral diagnostic for laser angiosurgery

A method for treatment of arterial tissue or obstructions comprising the steps of:

• (a) providing a catheter with a plurality of optical fibers in which the distal end of the catheter is enclosed by an optical shield transparent to light radiation and wherein the proximal end of the catheter and optical fibers may be coupled to a source of optical radiation of relatively high power and low power, the high power radiation being capable of removing tissue, and the low power radiation being capable of exciting fluorescence and scattering light, but not of removing tissue;
• (b) inserting said catheter into an artery until the optical shield is brought into contact with a suspected arterial lesion;
• (c) selecting an optical fiber and coupling the low power light at a wavelength of between about 430 to 530 nm from the light source to the proximal end of said optical fiber whereby the light enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end of said fiber out the optical shield and impinges on the suspected lesion, and the scattered and fluorescent light is returned to the proximal end of the selected optical fiber, and is coupled to a spectral analyzer wherein the fluorescence or scattered light excited by said light is analyzed to determine if the material contacted by the optical shield and, in particular, the portion irradiated by the incident light from the selected optical fiber is healthy arterial tissue or plaque or other material;
• (d) observing at the proximal end of the selected fiber the fluorescence excited by said light to analyze the spectral profile in the range 520-620 nm, where peaks occur;
• (e) in the event it is determined that the material is to be removed, coupling the proximal end of said selected optical fiber to the source of relatively high power radiation and coupling said radiation to the proximal end of said selected optical fiber whereby such radiation is transmitted through said fiber to the distal end to irradiate a portion of the tissue;
• (f) repeating the above steps until the lesion has been removed as needed.

A method of diagnosis of the type of tissue in an artery, including distinguishing artery wall from atheromateous plaque, comprising the steps of:

• (a) inserting a catheter containing a multiplicity of optical fibers into an artery, said catheter and fibers having proximal and distal ends with an optical shield means on the distal end of the catheter having an optically transparent enclosure with a distal output surface located a fixed distance from the distal ends of the fibers and extending over the end of the catheter and a distal surface for displacing body fluid such that direct contact can be made by said distal surface with such tissue within the artery and a laser source of light coupled to at least one of said fibers at a proximal end;
• (b) terminating said insertion when the optical shield is brought into contact with a suspected arterial lesion or other tissue to be diagnosed;
• (c) selecting an optical fiber coupled to said laser source and coupling said light to the proximal end of said optical fiber whereby the light enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end of said fiber out the optical shield and impinges on the suspected lesion to produce fluorescence and associated fluorescent light is returned to the proximal end of the selected optical fiber, and is coupled to a spectral analyzer wherein the fluorescent light is analyzed to determine if the material contacted by the optical shield and, in particular, the porton irradiated by the incident light from the selected optical fiber is healthy arterial tissue or plaque or other material, said analysis including:
• (i) observing at the proximal end of the selected fiber the fluorescence excited by said light to analyze the spectral profile in the range 520-610 nm, where peaks occur;
• and
• (ii) determining from ratios of fluorescence peak heights at about 550 nm and 600 nm and the valley at about 580 nm, whether the tissue being analyzed is artery wall, plaque, blood or other tissue.