Cutting balloon having sheathed incising elements

Abstract

A cutting balloon for use in a PTCA atherectomy procedure includes an elongated balloon that defines a longitudinal axis and is inflatable from a first deflated configuration to a second radially expanded configuration. One or more incising elements are mounted on the inflatable balloon. Compressible sheaths made of a relatively low durometer, flexible material are mounted on the balloon to protect the operative cutting surface of a respective incising element during assembly of the cutting balloon and transit of the cutting balloon to the treatment site. Each sheath extends farther from the longitudinal axis than the corresponding incising element and makes first contact with the tissue during a balloon inflation. Once contact has been established between the tissue and the sheath, further balloon inflation causes the sheath to radially compress between the tissue and the inflatable balloon exposing the operative cutting surface for tissue incision.

1 . A cutting balloon catheter for incising tissue at a treatment site in a body vessel of a patient, the cutting balloon catheter comprising:
 an elongate shaft having a proximal portion and a distal portion;   an inflatable balloon secured to the distal portion of the elongate shaft, the inflatable balloon being inflatable from a first deflated state to a second radially expanded state;   a cutting blade mounted on the inflatable balloon such that a cutting edge of the cutting blade is oriented radially outward from the inflatable balloon; and   a radially compressible sheath covering the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state, wherein the compressible sheath includes an engaging surface configured to contact an interior surface of the body vessel when the inflatable balloon is inflated to the second radially expanded state, the engaging surface located radially outward of the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state;   wherein the radially compressible sheath is configured to be radially compressed as the inflatable balloon is inflated to the second radially expanded state, exposing the cutting edge radially outward from the engaging surface of the radially compressible sheath.   
     
     
         2 . The cutting balloon catheter of  claim 1 , wherein the engaging surface of the radially compressible sheath is a flattened surface when the inflatable balloon is in the first deflated state. 
     
     
         3 . The cutting balloon catheter of  claim 1 , wherein the radially compressible sheath includes a pair of sheath members, wherein a first sheath member extends along a first side surface of the cutting blade and a second sheath member extends along a second side surface of the cutting blade. 
     
     
         4 . The cutting balloon catheter of  claim 3 , wherein the first side surface of the cutting blade converges with the second side surface of the cutting blade at the cutting edge of the cutting blade. 
     
     
         5 . The cutting balloon catheter of  claim 1 , wherein the radially compressible sheath encapsulates the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state. 
     
     
         6 . The cutting balloon catheter of  claim 1 , wherein the cutting edge has a length from a first end of the cutting edge to a second end of the cutting edge, wherein the radially compressible sheath covers the entire length of the cutting edge when the inflatable balloon is in the first deflated state. 
     
     
         7 . The cutting balloon catheter of  claim 1 , further comprising a mounting pad bonded to the balloon, a base portion of the cutting blade being embedded in the mounting pad. 
     
     
         8 . The cutting balloon catheter of  claim 7 , wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the radially compressible sheath has a length measured from a first end of the radially compressible sheath to a second end of the radially compressible sheath, the length of the mounting pad being greater than the length of the radially compressible sheath. 
     
     
         9 . The cutting balloon catheter of  claim 7 , wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the cutting edge of the cutting blade has a length measured from a first end of the cutting edge to a second end of the cutting edge, the length of the mounting pad being greater than the length of the cutting edge of the cutting blade. 
     
     
         10 . The cutting balloon catheter of  claim 7 , wherein the cutting blade includes opposing angled surfaces converging at the cutting edge, and the mounting pad contacts a portion of each of the opposing angled surfaces of the cutting blade. 
     
     
         11 . A cutting balloon catheter for incising tissue at a treatment site in a body vessel of a patient, the cutting balloon catheter comprising:
 an elongate shaft having a proximal portion and a distal portion;   an inflatable balloon secured to the distal portion of the elongate shaft, the inflatable balloon being inflatable from a first deflated state to a second radially expanded state;   a mounting pad secured to the inflatable balloon;   a cutting blade having a base portion embedded in the mounting pad such that a cutting edge of the cutting blade is oriented radially outward from the inflatable balloon; and   a radially compressible sheath covering the cutting edge of the cutting blade when the inflatable balloon is in the first deflated state which is configured to be radially compressed as the inflatable balloon is inflated to the second radially expanded state to expose the cutting edge;   wherein the mounting pad has a length measured from a first end of the mounting pad to a second end of the mounting pad, and the cutting edge of the cutting blade has a length measured from a first end of the cutting edge to a second end of the cutting edge, the length of the mounting pad being greater than the length of the cutting edge of the cutting blade.   
     
     
         12 . The cutting balloon catheter of  claim 11 , wherein the radially compressible sheath has a length measured from a first end of the radially compressible sheath to a second end of the radially compressible sheath, the length of the mounting pad being greater than the length of the radially compressible sheath. 
     
     
         13 . The cutting balloon catheter of  claim 11 , wherein the radially compressible sheath is attached to the mounting pad. 
     
     
         14 . The cutting balloon catheter of  claim 11 , wherein the radially compressible sheath includes a pair of sheath members, wherein a first sheath member extends along a first side surface of the cutting blade and a second sheath member extends along a second side surface of the cutting blade. 
     
     
         15 . The cutting balloon catheter of  claim 14 , wherein each of the first and second sheath members is formed as a hollow tube. 
     
     
         16 . The cutting balloon catheter of  claim 11 , wherein the cutting edge of the cutting blade is encapsulated in the radially compressible sheath when the inflatable balloon is in the first deflated state. 
     
     
         17 . The cutting balloon catheter of  claim 16 , wherein the cutting edge is configured to cut through the radially compressible sheath to expose the cutting edge when the inflatable balloon is inflated to the second radially expanded state. 
     
     
         18 . The cutting balloon catheter of  claim 11 , wherein the radially compressible sheath is substantially rectangular shaped in a plane normal to a longitudinal axis of the cutting blade. 
     
     
         19 . The cutting balloon catheter of  claim 11 , wherein the radially compressible sheath includes a flattened engaging surface when the inflatable balloon is in the first deflated state configured to contact tissue in the body vessel when the inflatable balloon is inflated to the second radially expanded state.