text: 1. Field of the Invention
  The present invention relates generally to angioplasty and catheterization devices, and particularly to such devices using laser technology to remove occlusions from blood vessels and organs of the body.
  2. Description of Related Axle
  Angioplasty, the repair of a blood vessel, may be performed in several ways. Angioplasty may take the form of surgery to replace the occluded portion of the clogged vessel with either a piece of the patient's own tissue or a prosthetic vessel. This type of angioplasty is relatively difficult to perform and involves considerable trauma to the patient.
  In balloon angioplasty, a balloon-tipped catheter is inserted into the clogged blood vessel and the balloon is inflated to expand the passageway of the blood vessel. Balloon angioplasty is not as difficult and traumatic as replacement surgery, but it does not actually remove the occlusion. Thus the vessel walls may return to their occluded position after a short period of time.
  Furthermore, balloon angioplasty is an option only where there is a passageway sufficiently open for the insertion of the balloon-tipped catheter. Accordingly, balloon angioplasty cannot be performed in cases where blood vessels have a high degree of occlusion.
  At the present, lasers used for angioplasty are steered by a guide wire which is pre-inserted through the clogged area of the vessel with the assistance of x-ray visualization. Unfortunately, this technique is not effective for highly occluded vessels because the occlusion prevents the insertion of the guide wire.
  Angioplasty lasers currently in use emit a laser beam having a wavelength in the ultraviolet range. This wavelength produces clean vaporization of tissue in its path with little thermal damage to the surrounding tissue. The catheter tip of such lasers, however, must be in contact with the tissue in order for vaporization to occur. The laser beam has no means of aiming other than the guide wire. Thus the area of vaporization is limited to the size of the lumen produced by the laser.
  Finally, the laser catheter in use today follows the guide wire blindly and vaporizes both the atherosclerotic tissue and the normal tissue in its path. With the guide wire technique, there is no capability for visually monitoring and controlling the laser angioplasty procedure as it is being performed.