Ablation instrument and method

Abstract

A flexible microwave antenna assembly for a surgical ablation instrument is capable of conforming to a tissue surface for ablation thereof. The ablation instrument includes a transmission line having a proximal portion suitable for connection to an electromagnetic energy source, and includes a flexible antenna coupled to the transmission line for radially generating an electric field sufficiently strong to cause tissue ablation. A flexible shield device is coupled to the antenna to substantially shield a surrounding area of the antenna from the electric field radially generated therefrom while permitting a majority of the field to be directed generally in a predetermined direction. A flexible insulator is disposed between the shield device and the antenna to define a window portion enabling the transmission of the directed electric field in the predetermined direction. The antenna, the shield device and the insulator are formed for selective manipulative bending thereof, as a unit, into contact positions that generally conform the window portion to the biological tissue surface to be ablated.

1 . A microwave ablation instrument adapted to ablate a surface of a biological tissue comprising: 
 a handle member formed for manual manipulation of said ablation instrument;    an elongated transmission line coupled to said handle member, and having a proximal portion disposed for connection to an electromagnetic energy source; and    a flexible antenna assembly coupled to said handle member and to the transmission line, and adapted to transmit an electric field out of a window portion thereof sufficiently strong to cause tissue ablation, said antenna assembly being formed for selective manipulative bending thereof to one of a plurality of contact positions to generally conform said window portion to the biological tissue surface to be ablated.    
     
     
         2 . The microwave ablation instrument according to  claim 1  wherein, said antenna assembly includes: 
 a flexible antenna coupled to the transmission line for radially generating said electric field; and    a flexible shield device to substantially shield a surrounding radial area of the antenna from the electric field radially generated therefrom while permitting a majority of the field to be directed generally in a predetermined direction.    
     
     
         3 . The microwave ablation instrument according to  claim 1  wherein, said antenna assembly further includes a flexible insulator disposed between the shield device and the antenna, and defining said window portion enabling the transmission of the directed electric field in the predetermined direction, said antenna, said shield device and said insulator being formed for selective manipulative bending thereof, as a unit, to said one of a plurality of contact positions.  
     
     
         4 . The microwave ablation instrument according to  claim 3  further including: 
 a bendable, malleable shaft having a proximal portion coupled to said handle member, and an opposite distal portion coupled to said antenna assembly.    
     
     
         5 . The microwave ablation instrument according to  claim 4  wherein, a proximal end of said antenna is operably coupled to a distal end of an inner conductor of said transmission line, and a proximal end of said shield device is operably coupled to a distal end of an outer conductor of said transmission line.  
     
     
         6 . The microwave ablation instrument according to  claim 5  wherein, said shaft is tubular and conductive having a distal portion conductively coupled to the proximal end of said shield device, and another portion conductively coupled to said outer conductor of said transmission line in a manner causing said shaft to form part of said transmission line.  
     
     
         7 . The microwave ablation instrument according to  claim 5  wherein, said shaft comprises a semi-rigid coaxial cable including an outer conductor and an inner conductor, the coaxial cable outer conductor having a distal portion conductively coupled to the proximal end of said shield device, and another portion of the coaxial cable outer conductor conductively coupled to said outer conductor of said transmission line, and the coaxial cable inner conductor having a proximal portion conductively coupled to a distal end of said inner conductor of said transmission line.  
     
     
         8 . The microwave ablation instrument according to  claim 5  wherein, said insulator is coupled to the distal portion of said shaft, and is generally cylindrical-shaped when oriented in a substantially linear normal position.  
     
     
         9 . The microwave ablation instrument according to  claim 8  wherein, said antenna is disposed between the shield device and the window portion longitudinally along said insulator.  
     
     
         10 . The microwave ablation instrument according to  claim 9  wherein, said window portion is substantially planar in the normal position.  
     
     
         11 . The microwave ablation instrument according to  claim 10  wherein, said shield device is in the shape of a semi-cylindrical shell having a longitudinal axis generally co-axial with a longitudinal axis of said insulator.  
     
     
         12 . The microwave ablation instrument according to  claim 11  wherein, a longitudinal axis of said antenna is off-set from a longitudinal axis of said insulator to position said antenna substantially proximate to and adjacent said window portion.  
     
     
         13 . The microwave ablation instrument according to  claim 12  wherein, said shield device includes a flexible braided metallic strip.  
     
     
         14 . The microwave ablation instrument according to  claim 11  further including: 
 an elongated, bendable, retaining member coupled longitudinally therealong to said insulator in a manner enabling the insulator to retain the one contact position after manipulative bending thereof for said conformance of the window portion to the biological tissue surface to be ablated.    
     
     
         15 . The microwave ablation instrument according to  claim 5  wherein, said insulator comprises a hydro-phobic material molded to the distal portion of said shaft.  
     
     
         16 . The microwave ablation instrument according to  claim 3  wherein, said insulator defines a receiving passage formed for sliding receipt of said antenna longitudinal therein during manipulative bending of the antenna assembly.  
     
     
         17 . The microwave ablation instrument according to  claim 3  further including: 
 a tube device positioned in said receiving passage proximate the distal end of said antenna, and having a bore formed and dimensioned for sliding longitudinal reciprocation therein of at least the distal end of said antenna.    
     
     
         18 . The microwave ablation instrument according to  claim 17  further including: 
 an elongated, bendable, retaining member coupled longitudinally therealong to said insulator in a manner enabling the insulator to retain the one contact position after manipulative bending thereof for said conformance of the window portion to the biological tissue surface to be ablated.    
     
     
         19 . The microwave ablation instrument according to  claim 3  further including: 
 an elongated, bendable, retaining member coupled longitudinally therealong to said insulator in a manner enabling the insulator to retain the one contact position after manipulative bending thereof for said conformance of the window portion to the biological tissue surface to be ablated.    
     
     
         20 . The microwave ablation instrument according to  claim 19  wherein, said retaining member is embedded in the flexible insulator.  
     
     
         21 . The microwave ablation instrument according to  claim 19  wherein, said retaining member comprises a metallic material having a transverse cross-sectional dimension sufficient to resist the resiliency of said insulator back to the normal position.  
     
     
         22 . The microwave ablation instrument according to  claim 21  wherein, said retaining member is disposed longitudinally along said insulator, and one of said shield device, and said antenna is disposed on an opposite side of said shield device, longitudinally along said insulator, and between the shield device and the window portion.  
     
     
         23 . The microwave ablation instrument according to  claim 7  further including: 
 a restraining sleeve adapted to limit the bending movement of said bendable antenna assembly at the conductive coupling between the shield device and the shaft.    
     
     
         24 . The microwave ablation instrument according to  claim 23  wherein, said restraining sleeve is formed and dimensioned to extend peripherally over the conductive coupling to limit said bending movement in a predetermined direction to maintain the integrity of conductive coupling.  
     
     
         25 . The microwave ablation instrument according to  claim 24  wherein, said shield device is in the shape of a semi-cylindrical shell having a longitudinal axis generally co-axial with a longitudinal axis of said insulator, and said restraining sleeve includes a curvilinear transverse cross-sectional dimension extending past said conductive coupling longitudinally therealong by an amount sufficient to maintain said integrity.  
     
     
         26 . The microwave ablation instrument according to  claim 6  wherein: 
 the transmission line is a coaxial transmission line disposed for transmission of microwave energy at frequencies in the range of approximately 800 to 6000 megahertz, the coaxial transmission line having a center conductor, a shield and a dielectric material disposed between the center conductor and shield.    
     
     
         27 . The microwave ablation instrument according to  claim 3  further including: 
 an elongated handle member having a distal grip portion and an opposite proximal portion coupled to a distal portion of said antenna assembly, said handle member disposed to selectively orient a bend of said antenna assembly for selectively urging the window portion in abutting contact with the biological tissue surface to be ablated.    
     
     
         28 . The microwave ablation instrument according to  claim 27  wherein, said insulator defines a receiving passage formed for sliding receipt of said antenna longitudinal therein during manipulative bending of the antenna assembly.  
     
     
         29 . The microwave ablation instrument according to  claim 27  wherein, said handle member comprises an elongated flexible rod having a diameter smaller than a diameter of said insulator.  
     
     
         30 . The microwave ablation instrument according to  claim 29  wherein, a longitudinal axis of said antenna is off-set from a longitudinal axis of said insulator to position said antenna substantially proximate to and adjacent said window portion, and a longitudinal axis of said flexible rod is off-set from the longitudinal axis of said insulator to position said rod in general axial alignment with said antenna, and adjacent said window portion.  
     
     
         31 . The microwave ablation instrument according to  claim 27 , wherein said handle member is a flexible elongated member having a proximal portion coupled to said transmission line, and an opposite a distal portion coupled to said antenna assembly.  
     
     
         32 . The microwave ablation instrument according to  claim 31 , wherein said flexible elongated member is a coaxial cable including an outer conductor and an inner conductor, the coaxial cable outer conductor having a distal portion conductively coupled to the proximal end of said shield device, and another portion of the coaxial cable outer conductor conductively coupled to said outer conductor of said transmission line, and the coaxial cable inner conductor having a proximal portion conductively coupled to a distal end of said inner conductor of said transmission line.