Fiber optic laser catheter and method of using it

Abstract

A fiber optic laser catheter assembly for use in removing, or largely debulking, obstructions or occlusions from a lumen in a living body. The catheter assembly includes an outer tubular sheath, an optical fiber extending through the sheath, and a fiber guide for holding the fiber within the sheath. In all of the disclosed embodiments, the obstructions are removed by controllably positioning an optical fiber's distal tip in a succession of selected radial and circumferential positions so as to sculpt away the obstruction without substantial risk of mechanically or thermally damaging the vessel. Several of the embodiments are configured such that the portion of the occlusion that can be reliably sculpted away has a radius greater even than the radius of the catheter assembly itself.

1 . Catheter apparatus for use with a laser in removing obstructions from a lumen of a living body, comprising: 
 a tubular outer sheath sized to be received within a lumen of a living body, the sheath having a longitudinal axis and a distal end proximal to an obstruction to be removed;    positioning means located, at least in part, radially outwardly of the sheath, for engaging the lumen wall and positioning the outer sheath at a selected radial position within the lumen;    an optical fiber extending through the sheath and having a proximal end attachable to a laser and a distal end located immediately adjacent to the obstruction; and    fiber guide means located within the sheath and adapted to support the optical fiber's distal end, the fiber guide means being rotatable within the sheath, about the sheath's longitudinal axis, and being further configured so as to allow the fiber's distal tip to be positioned at any selected radial and circumferential location relative to the sheath, such that the catheter apparatus can cooperate with the laser to remove at least a portion of the obstruction, without damaging the lumen wall.    
     
     
         2 . Catheter apparatus as defined in  claim 1 , wherein: 
 the fiber guide means includes a body and means defining a channel within the body sized to receive the optical fiber, the channel having an axis angularly skewed relative to the sheath's axis; and    the optical fiber is selectively movable axially within the channel of the fiber guide means such that the fiber's distal tip moves radially relative to the fiber guide means and the sheath.    
     
     
         3 . Catheter apparatus as defined in  claim 2 , wherein the optical fiber's distal tip is selectively movable between a location substantially coincident with the sheath's longitudinal axis and a location axially beyond, and radially outside, the sheath's distal end, to enable the apparatus to produce a lumen larger in diameter than that of the sheath.  
     
     
         4 . Catheter apparatus as defined in  claim 2 , wherein the axis of the channel defined by the fiber guide means intersects the sheath's longitudinal axis.  
     
     
         5 . Catheter apparatus as defined in  claim 1 , wherein: 
 the optical fiber is selectively movable radially relative to the fiber guide means; and    the fiber guide means is configured such that selectively moving the optical fiber axially relative to the fiber guide means positions the optical fiber's distal end radially relative to the sheath.    
     
     
         6 . Catheter apparatus as defined in  claim 1 , wherein the positioning means includes: 
 an inflatable bladder carried by the sheath; and    means for controllably inflating the bladder such that it enlarges in size and compressively engages the vessel wall, at a location radially outwardly of the sheath and proximal to the lesion to be removed.    
     
     
         7 . Catheter apparatus as defined in  claim 6 , wherein the positioning means is configured symmetrically and is operable to position the sheath substantially centrally within the vessel.  
     
     
         8 . Catheter apparatus as defined in  claim 1 , wherein the fiber guide means includes: 
 a body;    means defining a slot within the body sized to receive the optical fiber's distal end and to permit the fiber's distal end to be moved laterally within the slot, along an axis aligned substantially radially relative to the sheath; and    biasing means for moving the optical fiber's distal end to a selected radial location within the slot.    
     
     
         9 . Catheter apparatus as defined in  claim 8 , wherein the biasing means includes: 
 an inflatable bladder; and    means for inflating the bladder such that it enlarges in size and forcibly urges the optical fiber's distal end radially within the slot.    
     
     
         10 . Catheter apparatus as defined in  claim 1 , wherein: 
 the optical fiber is selectively movable axially relative to the sheath; and    the fiber guide means includes spring bias means for yieldably urging the optical fiber's distal end radially relative to the sheath by an angle that varies as the fiber guide means is moved axially relative to the sheath.    
     
     
         11 . Catheter apparatus as defined in  claim 10 , wherein: 
 the fiber guide means further includes 
 a substantially circumferentially-symmetrical body having a central passageway that terminates in a flared opening, and  
 an elongated fiber guide to carry the optical fiber's distal end, the fiber guide being sized to be received in the passageway of the body and to be axially and rotatably movable within the passageway;  
   the spring bias means is located on the exterior of the elongated fiber guide and is adapted to engage the flared opening of the body and move the optical fiber's distal end radially relative to the sheath by an angle that varies in accordance with the fiber guide's axial position relative to the sheath; and    the optical fiber is controllably movable axially relative to the fiber guide, to vary the radial position of the fiber's distal tip.    
     
     
         12 . Catheter apparatus as defined in  claim 1 , wherein: 
 the sheath is substantially cylindrical;    the fiber guide means has a substantially cylindrical outer surface having a diameter substantially the same as the inner diameter of the sheath, but is adapted to rotate freely within the sheath, about the sheath's longitudinal axis.    
     
     
         13 . Catheter apparatus as defined in  claim 1 , wherein the fiber guide means includes means defining a plurality of channels, each sized to receive the optical fiber and support the fiber's distal tip at a unique radial location.  
     
     
         14 . Catheter apparatus as defined in  claim 1 , wherein: 
 the fiber guide means includes a plurality of optical fiber holders, each holder sized to be separately slidably received within the sheath, and each holder including means defining a channel sized to receive the optical fiber, the channel of each holder having a unique radial position; and    each optical fiber holder enables the apparatus to cooperate with the laser to remove a different radial portion of the lesion.    
     
     
         15 . Catheter apparatus as defined in  claim 14 , wherein the channel defined in each of the plurality of optical fiber holders has a substantially cylindrical cross-section and an axis substantially parallel with the axis of the sheath.  
     
     
         16 . Catheter apparatus as defined in  claim 1 , wherein the optical fiber includes just a single optical fiber.  
     
     
         17 . A method for removing an obstruction from a lumen of a living body, comprising steps of: 
 providing a catheter assembly having 
 a tubular outer sheath sized to be received within a lumen of a living body, the sheath having a longitudinal axis and a distal end,  
 an actuatable positioning device located, at least in part, radially outwardly of the sheath, near the sheath's distal end,  
 an optical fiber extending through the sheath and having a proximal end attachable to a laser and a distal end located at or near the sheath'distal end, and  
 fiber guide means located within the sheath and adapted to support the optical fiber's distal end, the fiber guide means being rotatable within the sheath, about the sheath's longitudinal axis, and being further configured so as to allow the fiber's distal tip to be positioned at any selected radial and circumferential location relative to the sheath;  
   positioning the catheter assembly within a lumen of the living body, with the sheath's distal end proximal to an obstruction to be removed;    actuating the positioning device of the catheter assembly to engage a portion of the lumen wall spaced from the obstruction and thereby fix the sheath's distal end within the lumen; and    controllably positioning the optical fiber's distal tip, at least in part, by manipulating the fiber guide means, while energizing the laser, such that a laser beam is transmitted to selected radial and circumferential positions within the lumen, to remove at least a portion of the obstruction, without damaging the lumen wall.    
     
     
         18 . A method as defined in  claim 17 , wherein the step of controllably positioning includes steps of: 
 circumferentially positioning the optical fiber's distal tip by controllably rotating the fiber guide means within the sheath; and    radially positioning the optical fiber's distal tip.    
     
     
         19 . A method as defined in  claim 18 , wherein the step of radially positioning includes a step of controllably moving the optical fiber axially along a channel formed in the fiber guide means.  
     
     
         20 . A method as defined in  claim 18 , wherein the step of radially positioning includes a step of controllably inflating a bladder to bias the optical fiber's distal tip laterally within a radially-aligned slot formed in the fiber guide means.  
     
     
         21 . A method as defined in  claim 18 , wherein the step of radially positioning includes a step of placing the optical fiber in a selected one of a plurality of channels formed in the fiber guide means, each channel having a distal end located at a different radial position.  
     
     
         22 . A method as defined in  claim 18 , wherein the step of radially positioning includes a step of positioning within the sheath one of a plurality of separate fiber guide devices, each device having a channel with a distal end located at a different radial position.  
     
     
         23 . A method as defined in  claim 17 , wherein: 
 the positioning device of the catheter assembly includes an inflatable bladder located radially outwardly of the sheath, near the sheath's distal end; and    the step of actuating includes a step of inflating the bladder such that it expands radially outwardly and compressively engages a portion of the lumen wall proximal to the obstruction to be removed.