Apparatus and method incorporating an ultrasound transducer onto a delivery member

Abstract

A medical device assembly and method provides an ultrasound transducer mounted onto a catheter shaft. The ultrasound transducer is mounted such that there is a radial separation between the transducer and the underlying catheter shaft. The transducer is mounted on support structures which do not bridge the gap between the transducer and delivery member. The location of the support structures provides for an “airbacked” transducer that is very efficient and prevents heat build-up in the materials in contact therewith.

What is claimed is:  
     
         1 . An ultrasound ablation apparatus, comprising: 
 an elongate catheter body having an outer surface;    an expandable member disposed along said catheter body;    an ultrasound transducer assembly having an inner surface, said ultrasound transducer assembly being positioned along said catheter body within an interior portion of said expandable member; and    a support structure coupling said ultrasound transducer assembly to said catheter body, said support structure engaging only proximal and distal end portions of said ultrasound transducer assembly and maintaining a region of radial separation between said inner surface of said ultrasound transducer assembly and said outer surface of said catheter body.    
     
     
         2 . The ultrasound ablation apparatus of  claim 1 , wherein said support structure forms a seal to prevent external fluids from entering said region of radial separation.  
     
     
         3 . The ultrasound ablation apparatus of  claim 2 , wherein said ultrasound transducer assembly is substantially cylindrical in shape and wherein said ultrasound transducer assembly is suspended over said catheter body in a generally coaxial arrangement.  
     
     
         4 . The ultrasound ablation apparatus of  claim 3 , wherein said support structure comprises an insulating material with first and second band members surrounding said insulating material, said first band member having an inner surface in contact with an outer surface of said proximal end portion of said ultrasound transducer assembly, said second band member having an inner surface in contact with an outer surface of said distal end portion of said ultrasound transducer assembly.  
     
     
         5 . The ultrasound ablation apparatus of  claim 4 , wherein said first and second band members are metallic.  
     
     
         6 . The ultrasound ablation apparatus of  claim 5 , wherein said first and second band members are soldered to said ultrasound transducer assembly to form a seal to prevent external fluids from entering said region of radial separation.  
     
     
         7 . The ultrasound ablation apparatus of  claim 3 , wherein said support structure comprises first and second annular rings, each having an outer surface in contact with an inner surface of said ultrasound transducer assembly.  
     
     
         8 . The ultrasound ablation apparatus of  claim 7 , wherein said first and second annular rings are metallic.  
     
     
         9 . The ultrasound ablation apparatus of  claim 8 , wherein said first and second annular rings are soldered to said ultrasound transducer assembly.  
     
     
         10 . The ultrasound ablation apparatus of  claim 1 , wherein said expandable member is adapted to engage a circumferential region of tissue when in an expanded condition.  
     
     
         11 . The ultrasound ablation apparatus of  claim 10 , wherein said ultrasound transducer assembly is configured to emit ultrasound energy in a radial path to ablate at least a portion of said circumferential region of tissue.  
     
     
         12 . The ultrasound ablation apparatus of  claim 1 , wherein said elongate catheter body is pre-shaped to match a natural curvature of a body lumen.  
     
     
         13 . The ultrasound ablation apparatus of  claim 1 , wherein said elongate catheter body is steerable.  
     
     
         14 . The ultrasound ablation apparatus of  claim 1 , wherein said ultrasound transducer assembly comprises an ultrasound transducer and flanges extending proximal and distal to said ultrasound transducer for engagement with said support structure.  
     
     
         15 . The ultrasound ablation apparatus of  claim 1 , further comprising a thermocouple for monitoring a temperature along a region of tissue engaged by said expandable member.  
     
     
         16 . The ultrasound ablation apparatus of  claim 1 , wherein said catheter body further comprises a lumen and proximal and distal ports located within said expandable member for directing a cooling fluid between said ultrasound transducer assembly and said expandable member.  
     
     
         17 . The ultrasound ablation apparatus of  claim 1 , wherein said support structure comprises first and second braided metal tubular members disposed around said catheter body with an axial gap therebetween, said ultrasound transducer assembly being mounted to said first and second braided tubular members and bridging said axial gap.  
     
     
         18 . The ultrasound ablation apparatus of  claim 1 , wherein said support structure comprises first and second conically-shaped members, each member having a first end with a large diameter and a second end with a small diameter, said first and second members being disposed over said catheter body such that said first ends engage said inner surface of said ultrasound transducer assembly and said second ends engage said catheter body.  
     
     
         19 . A method of manufacturing an ultrasound ablation apparatus, comprising: 
 providing an elongate catheter body and a substantially cylindrical ultrasound transducer having an axial bore sized to receive said elongate catheter body;    positioning said ultrasound transducer over a portion of said catheter body;    to providing a plurality of mandrels between said ultrasound transducer and said catheter body for maintaining a region of radial separation therebetween;    applying support structure to couple said ultrasound transducer to said elongate catheter body while maintaining said region of radial separation therebetween; and    removing said plurality of mandrels.    
     
     
         20 . A method for treating arrhythmia using an ultrasound ablation apparatus, comprising: 
 providing an elongate catheter body having an expandable member disposed thereon and including an ultrasound transducer located within an interior of said expandable member, said ultrasound transducer being coupled to said catheter body by a support structure that engages only proximal and distal end portions of said ultrasound transducer and maintains a region of radial separation between said catheter body and said ultrasound transducer;    advancing said ultrasound transducer to a circumferential region of tissue;    expanding said expandable member to anchor said expandable member in said circumferential region of tissue; and    supplying energy to said ultrasound transducer for radially emitting ultrasound energy to ablate a portion of said circumferential region of tissue.