Microwave ablation instrument with flexible antenna assembly and method

Abstract

A flexible microwave antenna assembly for a surgical ablation instrument 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. The antenna assembly 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 which defines 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, to one of a plurality of contact positions to generally conform the window portion to the biological tissue surface to be ablated.

1 . A method of ablating tissue at a target tissue site, comprising the steps: 
 providing a flexible ablation device defining an outer ablation surface and comprising a means for directionally controlling ablation energy emitted therefrom;    manipulating the distal portion of the ablation device to generally conform the ablation surface to a tissue surface at the target tissue site;    applying ablation energy sufficient to ablate tissue at the target tissue site.    
     
     
         2 . The method of  claim 1 , wherein the ablation device comprises at least one ablation element.  
     
     
         3 . The method of  claim 2 , wherein the at least one ablation element is an antenna.  
     
     
         4 . The method of  claim 1 , wherein the ablation energy is one or more energies from the group consisting of: radiofrequency, microwave, and cryogenic.  
     
     
         5 . The method of  claim 1 , wherein the means for directionally controlling the ablation energy is a shield device adapted to direct the ablation energy in a single direction along a longitudinal axis of the ablation device, whereby the step of applying ablation energy results in the creation of a continuous lesion.  
     
     
         6 . The method of  claim 6 , wherein the step of applying ablation energy results in the isolation of at least one pulmonary vein from the epicardial surface of a patient's heart.  
     
     
         7 . A method for treatment of a heart comprising: 
 providing an ablation instrument having a flexible antenna assembly defining a window portion enabling the transmission of a directed electric field therethrough in a predetermined direction;    selectively bending the flexible antenna assembly to one of a plurality of contact positions to generally conform the shape of said window portion to the targeted biological tissue surface to be ablated;    manipulating the ablation instrument to strategically position the conformed window portion into contact with the targeted biological tissue surface; and    generating the electric field sufficiently strong to cause tissue ablation to the targeted biological tissue surface.    
     
     
         8 . The method of  claim 7 , wherein said flexible antenna assembly includes: 
 a flexible antenna for radially generating the electric field;    a flexible shield device coupled to said 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 the predetermined direction; and    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.    
     
     
         9 . The method of  claim 8 , further including: 
 repeating the bending, manipulating and generating events to form a plurality of strategically positioned ablation lesions.    
     
     
         10 . The method of  claim 9 , wherein the lesions are formed to create a predetermined conduction pathway in the muscular tissue wall of the targeted biological tissue and/or to divide the left and/or right atria to substantially prevent reentry circuits.  
     
     
         11 . The method of  claim 8 , 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.    
     
     
         12 . The method of  claim 1 , wherein said retaining member is embedded in the flexible insulator.  
     
     
         13 . The method of  claim 7 , wherein the heart remains beating throughout the bending, manipulating and generating events.  
     
     
         14 . The method of  claim 7 , further including: 
 arresting the patient's heart.    
     
     
         15 . The method of  claim 7 , further including: 
 temporarily arresting the patient's heart.    
     
     
         16 . The method of  claim 7 , wherein said ablation instrument is a microwave ablation instrument.  
     
     
         17 . A method for ablating medically refractory atrial fibrillation of the heart comprising: 
 providing an ablation instrument having a flexible antenna assembly adapted to generate an electric field sufficiently strong to cause tissue ablation, said antenna assembly defining a window portion enabling the transmission of the electric field therethrough in a predetermined direction;    selectively bending and retaining the flexible antenna assembly in one of a plurality of contact positions to generally conform the shape of said window portion to the targeted biological tissue surface to be ablated;    manipulating the ablation instrument to strategically position the conformed window portion into contact with the targeted biological tissue surface; and    forming an elongated lesion in the targeted biological tissue surface through the generation of the electric field by the antenna assembly.    
     
     
         18 . The method of  claim 17 , wherein said flexible antenna assembly includes: 
 a flexible antenna for radially generating the electric field;    a flexible shield device coupled to said 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 the predetermined direction; and    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.    
     
     
         19 . The method of  claim 18 , further including: 
 repeating the bending, manipulating and generating events to form a plurality of strategically positioned ablation lesions and/or to divide the left and/or right atria to substantially prevent reentry circuits.    
     
     
         20 . The method of  claim 19 , wherein the lesions are formed to create a predetermined conduction pathway between a sinoatrial node and an atrioventricular node of the heart.  
     
     
         21 . The method of  claim 19 , wherein said repeating the bending, manipulating and generating events are applied in a manner isolating the pulmonary veins from the epicardium of the heart.  
     
     
         22 . The method of  claim 18 , 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.    
     
     
         23 . The method of  claim 22 , wherein said retaining member is embedded in the flexible insulator.  
     
     
         24 . The method of  claim 17 , wherein the heart remains beating throughout the bending, manipulating and generating events.  
     
     
         25 . The method of  claim 23 , wherein said biological tissue surface includes the epicardium of the heart during a minimally invasive heart procedure.  
     
     
         26 . The method of  claim 17 , further including: 
 arresting the patient's heart.    
     
     
         27 . The method of  claim 17 , further including: 
 temporarily arresting the patient's heart.    
     
     
         28 . The method of  claim 26 , wherein said biological tissue surface includes the endocardium of one of the left atrium and the right atrium during an open-heart procedure.  
     
     
         29 . The method of  claim 17 , wherein said ablation instrument is a microwave ablation instrument.  
     
     
         30 . The method of  claim 17 , wherein 
 said ablation instrument includes an elongated flexible gripping member having a distal grip portion and an opposite proximal portion coupled to a distal portion of said antenna assembly, and a handle member coupled to a proximal portion of said antenna assembly; and    said manipulating includes manually gripping said flexible gripping member and said handle member to cooperatively and selectively bend said antenna assembly to selectively urge the window portion in abutting contact with the biological tissue surface to be ablated.    
     
     
         31 . The method of claim  30 , wherein said handle member is a flexible elongated member.