System for tissue ablation using pulsed laser

Abstract

Systems for enabling delivery of very high peak power laser pulses through optical fibers for use in ablation procedures preferably in contact mode. Such lasers advantageously emit at 355 nm wavelength. Other systems enable selective removal of undesired tissue within a blood vessel, while minimizing the risk of damaging the blood vessel itself, based on the use of the ablative properties of short laser pulses of 320 to 400 nm laser wavelength, with selected parameters of the mechanical walls of the tubes constituting the catheter, of the laser fluence and of the force that is applied by the catheter on the tissues. Additionally, a novel method of calibrating such catheters is disclosed, which also enables real time monitoring of the ablation process. Additionally, novel methods of protecting the fibers exit facets are disclosed.

1 .- 13 . (canceled) 
     
     
         14 . A device for selective cutting within blood vessels, wherein said device comprises:
 a pulsed laser coupled to a plurality of optical fibers, such that a flux of energy is emitted from said fibers, and   tubes acting as boundaries to said plurality of fibers, each of said tubes having a blunt distal edge in the same axial plane as the output end of said plurality of fibers, such that when a distal force is applied to said device, said blunt distal edges push through atheromatous material in said blood vessel in the region where said flux of energy is emitted from said fibers, and   wherein the ratio of the total core area from which said flux of energy is emitted to the total distal tip area of said device is at least 25%, and   wherein the wavelength of said pulsed laser is between 320 nm and 420 nm.   
     
     
         15 . The device according to  claim 14 , wherein said ratio is in the range of 30% to 40%. 
     
     
         16 . The device according to  claim 14 , wherein said laser is a third harmonic Nd:YAG laser emitting at 355 nm. 
     
     
         17 . The device according to  claim 14 , wherein said flux is at least 50 mJ/mm 2 . 
     
     
         18 . The device according to  claim 14 , wherein said flux is in the range of 50 to 80 mJ/mm 2 . 
     
     
         19 . The device according  claim 14 , wherein said flux is in the range of 65 to 80 mJ/mm 2 . 
     
     
         20 . The device according to  claim 14 , wherein said plurality of fibers is a bundle of fibers. 
     
     
         21 . The device according to  claim 20 , wherein the overall width of each of said tubes and said fibers is less than 400 μm and more than 200 μm. 
     
     
         22 . The device according to  claim 14 , wherein dyes or substrates are used to enhance absorption at desired wavelengths. 
     
     
         23 . The device according to  claim 22 , wherein the said dye is tetracycline and the desired wavelength is 355 nm.