Angioplasty system having means for identification of atherosclerotic plaque

An angioplasty method comprising the steps of:

• directing laser energy for stimulation of fluorescence by noncalcified atherosclerotic plaque and laser energy for stimulation of photoemission by calcified atherosclerotic plaque through a laser catheter to a target site in a blood vessel, the step of directing laser energy for stimulation of photoemission including directing a laser pulse through the laser catheter;
• analyzing a spectrum of the fluorescence emitted by tissue at the target site to determine whether the florescence is representative of noncalcified atherosclerotic plaque;
• analyzing photoemission by tissue at the target site to determine whether the photoemission is representative of calcified atherosclerotic plaque;
• directing high power laser energy through the laser catheter to the target site if the analyzing steps indicate the presence of atherosclerotic plaque;
• and
• detecting a defective condition of an optical fiber in said laser catheter by analyzing a tim domain signal responsive to photoemission received from the laser catheter and determining if the time domain signal is representative of a defective condition of said optical fiber, the step of analyzing a time domain signal including determining an area under the time domain signal beginning a predetermined time after the start of the laser pulse and indicating a defective condition of the optical fiber when said area exceeds a predetermined value.