Atherosclerotic plaque is known to build up on the walls of arteries in the human body. Such plaque build-up restricts circulation and often causes cardiovascular problems, especially when the build-up occurs in coronary arteries. Other body passages such as the esophagus, ureter and bile ducts, for example, are subject to blockage by tumorous tissue. Accordingly, it is desirable to remove or otherwise reduce plaque build-up and other tissue obstructions from such body passages.
Known catheters use laser energy to remove plaque build-up on artery walls. One such known catheter has a laser source and a catheter body. The catheter body has a proximal end and a distal end, or head, and multiple optical fibers extending between the proximal and distal ends. The laser source is coupled to the optical fibers at the proximal end of the catheter body and is configured to transmit laser energy through the optical fibers.
To remove an obstruction from a body passage, such as atherosclerotic plaque in an artery, the catheter is positioned in the artery so that the distal end of the catheter is adjacent to the plaque. The laser source is then energized so that laser energy travels through the optical fibers and photoablates the plaque adjacent the distal end of the catheter. The catheter is then advanced further through the artery to photoablate the next region of plaque build-up.
While known laser catheters are generally acceptable for removing small obstructions, such catheters are limited to opening a path the size of the catheter head on each pass through the body passage. The multiple passes which are required for removing larger areas of obstruction increase the possibility of damaging the passage inner wall. In addition, multiple passes increase the possibility that a piece of the obstruction will break free, enter the blood stream and result in vessel blockage. Other known laser catheters are limited by the relative inflexibility of the catheter distal end which may inflict damage to body passage inner walls as the catheter is advanced.
Accordingly it would be desirable to provide a laser catheter which can remove substantial portions of an obstruction in a single pass. It would also be desirable to provide a laser catheter having a flexible, adjustable distal end which can substantially conform to the inner dimensions of the body passageway to minimize damage to the inner wall. It would be further desirable to provide a laser catheter which can expand and contract during photoablation to increase the area of obstruction which may be photoablated in a single pass through a body passage.