Laser ablation catheters having expanded distal tip windows for efficient tissue ablation

Abstract

Laser ablation catheters and methods of using same for efficient tissue ablation are disclosed. In some cases, laser ablation catheter embodiments may include expanded distal tips that allow for beam energy expansion and reduce dead space at the distal cutting surface of the laser ablation catheter.

What is claimed is: 
     
         1 . A laser ablation catheter to ablate blockages in body lumens, comprising:
 a liquid filled waveguide including an elongate catheter body tube having an inner layer with a first index of refraction and an optical fluid disposed within an inner lumen of the elongate catheter body tube, with the optical fluid having a second index of refraction which is greater than the first index of refraction; and   a distal optical window disposed in liquid sealed relation to a surface of the elongate catheter body tube at a distal end of the elongate catheter body tube, the distal optical window including:
 an insert segment which is disposed within the inner lumen of a distal section of the elongate catheter body tube, and 
 an expanded segment which is disposed distally of the insert segment, which comprises a material configured to efficiently transmit optical energy for ablation of blockages in body lumens, which has an outer diameter which is greater than an outer diameter of the insert segment, and which has an axial length sufficient to allow optical energy expansion within the expanded segment. 
   
     
     
         2 . The laser ablation catheter of  claim 1  wherein the insert segment comprises silica or sapphire. 
     
     
         3 . The laser ablation catheter of  claim 1  further comprising a layer of material disposed about an outer surface of the insert segment which includes an index of refraction lower than an index of refraction of the material of the insert segment or a reflective material. 
     
     
         4 . The laser ablation catheter of  claim 1  wherein the inner layer of the catheter body tube comprises an amorphous fluoropolymer. 
     
     
         5 . The laser ablation catheter of  claim 3  wherein the layer of material disposed about the outer surface of the insert segment comprises an amorphous fluoropolymer. 
     
     
         6 . The laser ablation catheter of  claim 3  wherein the layer of material disposed about the outer surface of the insert segment comprises a reflective material and further comprises a dielectric material or metal. 
     
     
         7 . The laser ablation catheter of  claim 1  wherein the expanded segment is not configured to act as a waveguide. 
     
     
         8 . The laser ablation catheter of  claim 1  further comprising an input optical window disposed in liquid sealed relation with a proximal end of the catheter body tube.