Methods of ablating tissue using a catheter injection system

Abstract

At the present time, physicians often treat patients with atrial fibrillation (AF) using radiofrequency (RF) catheter systems to ablate conducting tissue in the wall of the Left Atrium of the heart around the ostium of the pulmonary veins. These systems are expensive and take time consuming to use. The present invention circular ablation system CAS includes a multiplicity of expandable needles that can be expanded around a central axis and positioned to inject a fluid like ethanol to ablate conductive tissue in a ring around the ostium of a pulmonary vein quickly and without the need for expensive capital equipment. The expansion of the needles is accomplished by self-expanding or balloon expandable structures. The invention includes centering means so that the needles will be situated in a pattern surrounding the outside of the ostium of a vein. Also included are members that limit the distance of penetration of the needles into the wall of the left atrium. The present invention also has application to ablating tissue around the ostium of a renal artery for the treatment of hypertension.

1 - 8 . (canceled) 
     
     
         9 . A method of treating a target tissue, the method including:
 advancing an ablation system through a target vessel until a distal end of the ablation system lies near the target tissue, the ablation system including injection needles, the ablation system designed to allow injection of ablative fluid through the injection needles;   centering the ablation system with respect to the target vessel by expanding an expandable structure, wherein the expandable structure comprises a balloon;   advancing the injection needles at least partially through a wall of the target vessel and into the target tissue; and   injecting ablative fluid into the target tissue through the injection needles.   
     
     
         10 . The method of  claim 9  wherein the ablative fluid comprises alcohol. 
     
     
         11 . The method of  claim 9  wherein the ablation system comprises three injection needles. 
     
     
         12 . The method of  claim 9  wherein the expandable structure is near the distal end of the ablation system. 
     
     
         13 . The method of  claim 9  wherein the expandable structure is configured help to ensure that the injection needles will be engaged circumferentially around the target vessel. 
     
     
         14 . The method of  claim 9  wherein the balloon comprises a conical portion. 
     
     
         15 . The method of  claim 9  wherein the balloon comprises a cylindrical portion. 
     
     
         16 . The method of  claim 9  wherein the balloon is configured to be inflated to be slightly less than a diameter of the target vessel. 
     
     
         17 . The method of  claim 9  wherein the balloon comprises a low pressure elastic balloon. 
     
     
         18 . The method of  claim 9  wherein the balloon comprises a non-compliant balloon. 
     
     
         19 . The method of  claim 9  wherein the balloon comprises a semi-compliant balloon. 
     
     
         20 . A method of treating a target tissue, the method including:
 advancing an ablation system through a target vessel until a distal end of the ablation system lies near the target tissue, the ablation system including injection needles;   centering the ablation system with respect to the target vessel by expanding a balloon of the ablation system outward toward a lumenal wall of the target vessel;   advancing the injection needles at least partially through the lumenal wall and into the target tissue, wherein the balloon is configured to allow the injection needles to be centered with respect to the target vessel; and   injecting ablative fluid into the target tissue through the injection needles.   
     
     
         21 . The method of  claim 20  where the ablative fluid comprises alcohol. 
     
     
         22 . The method of  claim 20  wherein the ablation system comprises at least two injection needles. 
     
     
         23 . The method of  claim 20  wherein the balloon comprise a cylindrical portion. 
     
     
         24 . A method of treating a target tissue, the method including:
 advancing an ablation system through a target vessel until a distal end of the ablation system lies near the target tissue, the ablation system including injection needles;   centering the ablation system with respect to the target vessel by expanding a balloon of the ablation system, wherein the balloon is configured to enable the circumferential deployment of the injection needles;   advancing the injection needles at least partially through the lumenal wall and into the target tissue; and   injecting ablative fluid into the target tissue through the injection needles.   
     
     
         25 . The method of  claim 24  further including deflating the balloon. 
     
     
         26 . The method of  claim 24  wherein the balloon is inflated with a saline solution. 
     
     
         27 . The method of  claim 24  wherein the method is for the treatment of hypertension. 
     
     
         28 . The method of  claim 24  wherein the injection needles penetrate a fixed distance.