High impedance electrode tip

Abstract

An implantable lead, being either a fixed or retractable/extendable lead, having a distal tip electrode is adapted for implantation on or about the heart and for connection to a system for monitoring or stimulating cardiac activity. The electrode includes a mechanical fastener such as a fixation helix for securing the electrode to cardiac tissue, which may or may not be electrically active. The implantable electrode with a helical tip includes an electrode which has a distal end and a proximal end. A helix is disposed within the electrode, where the helix is aligned along a radial axis of the electrode. The electrode further includes one or more of the following features: the helix having a coating of an insulating material on a surface of the helix, a porous conductive surface at a base of the helix, or a porous conductive element at the end of the electrode having an insulating coating covering from 5-95% of the surface of the porous conductive element. The electrode may further include an electrode tip having a porous electrical conductive element, such as a mesh screen, disposed on a surface at the distal end of the electrode tip, which can be used as a sensing or pacing interface with the cardiac tissue.

What is claimed:  
     
         1 . A distal tip electrode adapted for implantation on or about the heart and for connection to a system for monitoring or stimulating cardiac activity, said electrode comprising: 
 an electrode tip;    a mesh screen disposed at a distal end of the electrode tip;    a surface at the distal end of the electrode tip;    a fixation device disposed within said electrode, said fixation device adapted for travel along radial axis of the electrode through said surface;    a guiding mechanism for directing movement of the fixation device during travel; and    a movement assembly, said movement assembly for providing movement to said fixation device.    
     
     
         2 . The distal tip electrode as recited in  claim 1 , wherein said fixation device comprises a helix.  
     
     
         3 . The distal tip electrode as recited in  claim 1 , wherein said movement assembly comprises a piston.  
     
     
         4 . The distal tip electrode as recited in  claim 3 , wherein the piston has a slot therein, and the base further comprises a knob, said slot for mating with said knob.  
     
     
         5 . The distal tip electrode as recited in  claim 3 , wherein the slot is mated with said knob to form a stop mechanism for said fixation device.  
     
     
         6 . The distal tip electrode as recited in  claim 1 , wherein the mesh screen has a groove guide disposed therein.  
     
     
         7 . The distal tip electrode as recited in  claim 3 , wherein said distal tip electrode further comprises a seal, said seal disposed between said piston and said base.