Irrigated ablation catheter having magnetic tip for magnetic field control and guidance

Abstract

Embodiments of the present invention provide an irrigated ablation electrode assembly for use with an irrigated catheter device comprises at least one passageway for a fluid with an outlet disposed at an external surface of the electrode assembly; a permanent magnet; a shield separating the permanent magnet from the at least one passageway and from an exterior, the shield being substantially less oxidizable than the permanent magnet; and an electrode having an external electrode surface. A catheter guidance control and imaging system drives the permanent magnet to guide and control the catheter tip. In specific embodiments, the irrigation fluid flow paths through the electrode assembly are thermally insulated from the electrode and temperature sensor. The irrigation fluid is directed at target areas where coagulation is more likely to occur. One or more monitoring electrodes are provided for mapping or other monitoring functions.

1 . An irrigated ablation electrode assembly for use with an irrigated catheter device, the irrigated ablation electrode assembly comprising: 
 at least one passageway for a fluid with an outlet disposed at an external surface of the electrode assembly;    a permanent magnet;    a shield separating the permanent magnet from the at least one passageway and from an exterior, the shield being substantially less oxidizable than the permanent magnet; and    an electrode having an external electrode surface.    
   
   
       2 . The irrigated ablation electrode assembly of  claim 1 , wherein the electrode forms at least a portion of the shield, and wherein the electrode comprises an electrically conductive material that is substantially less oxidizable than the permanent magnet.  
   
   
       3 . The irrigated ablation electrode assembly of  claim 2  wherein the electrically conductive material is selected from the group consisting of platinum, gold, tantalum, iridium, stainless steel, palladium, and mixtures thereof, and wherein the electrically conductive material is plated onto a substrate made of a biocompatible material that is substantially less oxidizable than the permanent magnet.  
   
   
       4 . The irrigated ablation electrode assembly of  claim 1  wherein the shield comprises one or more materials selected from the group consisting of silicone, polyimide, platinum, gold, tantalum, iridium, stainless steel, palladium, and mixtures thereof.  
   
   
       5 . The irrigated ablation electrode assembly of  claim 1  wherein the permanent magnet comprises NdFeB.  
   
   
       6 . The irrigated ablation electrode assembly of  claim 1  further comprising at least one mapping electrode spaced proximally from the electrode which is a distal electrode capable of ablation.  
   
   
       7 . The irrigated ablation electrode assembly of  claim 1  wherein the electrode is disposed at a distal portion of the electrode assembly, and wherein the electrode assembly further comprises a proximal portion which includes at least one proximal passageway for a fluid with an outlet disposed at an external surface of the proximal portion.  
   
   
       8 . The irrigated ablation electrode assembly of  claim 7  wherein the proximal portion comprises a material which is electrically nonconductive and has a lower thermal conductivity than a material of the electrode.  
   
   
       9 . The irrigated ablation electrode assembly of  claim 7  wherein the at least one proximal passageway extends toward the electrode at an acute angle with respect to the longitudinal axis of the proximal portion.  
   
   
       10 . The irrigated ablation electrode assembly of  claim 7  wherein the proximal portion comprises a material which is electrically nonconductive, and wherein the external surface of the proximal portion and the external electrode surface of the electrode at the distal portion meet at an intersection, and wherein the at least one proximal passageway is configured to direct a fluid flow through the outlet toward a region adjacent the intersection.  
   
   
       11 . The irrigated ablation electrode assembly of  claim 7  wherein the permanent magnet is disposed in the distal portion, and wherein the electrode assembly further comprises at least one temperature sensor disposed in the permanent magnet.  
   
   
       12 . The irrigated ablation electrode assembly of  claim 1  wherein the electrode includes at least one electrode passageway for a fluid with an outlet disposed at the external electrode surface.  
   
   
       13 . The irrigated ablation electrode assembly of  claim 12  wherein the at least one electrode passageway is thermally insulated from the distal member by a poor thermal conductive material which is lower in thermal conductivity than a material of the electrode.  
   
   
       14 . The irrigated ablation electrode assembly of  claim 12  wherein the permanent magnet comprises an annular permanent magnet with an axial opening to permit fluid flow to the at least one electrode passageway, and wherein the electrode assembly further comprises a fluid lumen extending through the axial opening of the annular permanent magnet to the at least one electrode passageway.  
   
   
       15 . The irrigated ablation electrode assembly of  claim 14  wherein the fluid lumen comprises stainless steel braided polyimide forming a portion of the shield, and wherein the electrode forms another portion of the shield.  
   
   
       16 . The irrigated ablation electrode assembly of  claim 15  wherein the shield includes a silicone seal to prevent fluid from reaching the annular permanent magnet via a junction between the electrode and the fluid lumen.  
   
   
       17 . The irrigated ablation electrode assembly of  claim 12  wherein the electrode is disposed at a distal portion of the electrode assembly, and wherein the electrode assembly further comprises a proximal portion which includes at least one proximal passageway for a fluid with an outlet disposed at an external surface of the proximal portion, wherein the proximal portion comprises a material which is electrically nonconductive, wherein the external surface of the proximal portion and the external electrode surface of the electrode at the distal portion meet at an intersection, and wherein the at least one proximal passageway is configured to direct a fluid flow through the outlet toward a region adjacent the intersection.  
   
   
       18 . An irrigated ablation electrode assembly for use with an irrigated catheter device, the irrigated ablation electrode assembly comprising: 
 a permanent magnet,    at least one passageway for a fluid with an outlet disposed at an external surface of the electrode assembly, the at least one passageway extending through the permanent magnet;    an inner shield separating the permanent magnet from the at least one passageway, the inner shield being substantially less oxidizable than the permanent magnet; and    an outer shield separating the permanent magnet from an exterior, the outer shield being substantially less oxidizable than the permanent magnet.    
   
   
       19 . The irrigated ablation electrode assembly of  claim 18  wherein the inner shield comprises a fluid lumen supplying fluid to the at least one passageway.  
   
   
       20 . The irrigated ablation electrode assembly of  claim 18  further comprising an electrode having an external electrode surface, and wherein the electrode forms at least a portion of the outer shield.  
   
   
       21 . The irrigated ablation electrode assembly of  claim 20  wherein the electrode is disposed at a distal portion of the electrode assembly, wherein the electrode assembly further comprises a proximal portion having a material which is electrically nonconductive, and wherein the proximal portion forms at least a portion of the inner shield.  
   
   
       22 . A catheter comprising: 
 a shaft; and    an irrigated ablation electrode assembly coupled to a distal end of the shaft, the irrigated ablation electrode assembly having at least one passageway for a fluid with an outlet disposed at an external surface of the electrode assembly; a permanent magnet; a shield separating the permanent magnet from the at least one passageway and from an exterior, the shield being substantially less oxidizable than the permanent magnet; and an electrode having an external electrode surface.    
   
   
       23 . The catheter of  claim 22  wherein the electrode is disposed at a distal portion of the electrode assembly, and wherein the electrode assembly further comprises a proximal portion which includes at least one proximal passageway for a fluid with an outlet disposed at an external surface of the proximal portion.  
   
   
       24 . The catheter of  claim 22  wherein the electrode includes at least one electrode passageway for a fluid with an outlet disposed at the external electrode surface, wherein the permanent magnet comprises an annular permanent magnet with an axial opening to permit fluid flow to the at least one electrode passageway, and wherein the catheter further comprises a fluid lumen extending through the axial opening of the annular permanent magnet to the at least one electrode passageway.  
   
   
       25 . The catheter of  claim 22  further comprising a second permanent magnet disposed near the distal end of the shaft and spaced from the permanent magnet in the irrigated ablation electrode assembly.