Laser-based method and system for selectively processing target tissue material in a patient and optical catheter assembly for use therein

1. A system for selectively processing target tissue material in a patient, the system comprising:

a laser subsystem for generating an output laser beam; and

a catheter assembly including an optical fiber having a proximal end coupled to the laser subsystem for guiding the output laser beam along a propagation path, the beam having optical and temporal properties and a predetermined selected wavelength, wherein the predetermined selected wavelength is between 1700 nm and 1760 nm, the catheter assembly sized to extend through an opening in a first part of the patient and to a tissue material processing site within the patient, the catheter assembly further including a beam delivery and focusing subsystem having an adjustable focal distance and disposed in the propagation path and that accepts the output laser beam and adjustably positions the beam into at least one focused spot on the target tissue material disposed within a second part of the patient at the site based on distance to the target tissue material from a predetermined point on the propagation path at the site for a duration sufficient to allow laser energy to be absorbed by the target tissue material and converted to heat to produce a desired physical change in the target tissue material without causing undesirable changes to adjacent non-target material disposed within the second part of the patient wherein the target tissue material is characterized by an absorptive coefficient, and wherein the predetermined wavelength is selected to achieve a penetration depth into the second part of the patient of approximately one millimeter or more.

2. The system as claimed in claim 1 , wherein the predetermined wavelength is based on the absorptive coefficient of the target tissue material, wherein the adjacent non-target material has an absorptive coefficient different from the absorptive coefficient of the target tissue material at the predetermined wavelength.

3. The system as claimed in claim 1 , wherein the catheter assembly includes a plurality of optical components disposed along the propagation path.

4. The system as claimed in claim 3 , further comprising an actuator for varying distance between a pair of the optical components along the propagation path to change the focal distance.

5. The system as claimed in claim 4 , wherein the pair of optical components include a focusing lens and a mirror for bending the output laser beam.

6. The system as claimed in claim 1 , wherein the target tissue material comprises myelin sheath of at least a part of the nervous system.

7. The system as claimed in claim 1 , wherein the target material is located within a wall of part of a cardiovascular system at the target material processing site.

8. The system as claimed in claim 1 , wherein the laser beam is a pulsed laser beam, and the pulsed laser beam has a pulse width shorter than several milliseconds.

9. An optical catheter assembly for use in a system for selectively processing target tissue material in a patient, the assembly comprising:

an elongated flexible housing;

an optical fiber disposed in the housing for guiding an output laser beam along a propagation path, the beam having optical and temporal properties and a predetermined selected wavelength, wherein the predetermined selected wavelength is between 1700 nm and 1760 nm, the housing sized to extend through an opening in a first part of the patient and to a tissue material processing site within the patient; and

a beam delivery and focusing subsystem having an adjustable focal distance disposed in the propagation path and that accepts the output laser beam and adjustably positions the beam into at least one focused spot on the target tissue material disposed within a second part of the patient at the site based on distance to the target tissue material from a predetermined point on the propagation path at the site for a duration sufficient to allow laser energy to be absorbed by the target tissue material and converted to heat to produce a desired physical change in the target tissue material without causing undesirable changes to adjacent non-target material disposed within the second part of the patient wherein the target tissue material is characterized by an absorptive coefficient, the predetermined wavelength being based on the absorptive coefficient of the target tissue material, wherein the adjacent non-target material has an absorptive coefficient different from the absorptive coefficient of the target tissue material at the predetermined wavelength.

10. The assembly as claimed in claim 9 , wherein the predetermined wavelength is selected to achieve a penetration depth into the second part of the patient of approximately one millimeter or more.

11. The assembly as claimed in claim 9 , wherein the catheter assembly includes a plurality of optical components disposed along the propagation path.

12. The assembly as claimed in claim 11 , further comprising an actuator for varying distance between a pair of the optical components along the propagation path to change the focal distance.

13. The assembly as claimed in claim 12 , wherein the pair of optical components include a focusing lens and a mirror for bending the output laser beam.

14. The assembly as claimed in claim 9 , wherein the target tissue material comprises myelin sheath of at least a part of the nervous system.

15. The assembly as claimed in claim 9 , wherein the target material is located within a wall of part of a cardiovascular system at the target material processing site.

16. The assembly as claimed in claim 9 , wherein the laser beam is a pulsed laser beam, and the pulsed laser beam has a pulse width shorter than several milliseconds.